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www.biosensor2016.hacettepe.edu.tr
5-7 October 2016 Ankara, Turkey
Biosensors 2016
3rd International Congress on Biosensors Biomaterials, Bioinformatics, Biosensors, Electrochemistry, Nanobiotechnology, Nanomaterials, Single-cell detection & analysis, Natural & synthetic receptors, MicroPADs, Microfluidic systems and more….
Hacettepe University, Mehmet Akif Ersoy Hall, Beytepe Campus
Organized by
Hacettepe University Gazi University Bilkent University
Dear Colleagues,
It was a great pleasure for us to see you in the 3rd International Congress on Biosensors. The
congress was organized by Hacettepe University with the jointly contribution of Bilkent and
Gazi Universities.
Located at the capital of Turkey, the congress attracted top scientists, decision and policy
makers, high-tech companies, start-up companies, entrepreneurs, investors and students from
all around the region.
This three day Conference provided access to the most up-to-date and authoritative
knowledge from both commercial and academic worlds, sharing best practice in the field as
well as learning about case studies of successfully integrated bio-sensing technologies. The
meeting provided the opportunity to highlight recent developments and helped many to
identify the emerging and future areas of growth in this exciting field.
We are so happy to have you welcomed to Ankara for 3rd International Congress on
Biosensors.
Sincerely yours,
Assoc. Prof. Dr. Memed Duman
3rd International
Congress on Biosensors
5-7 October 2016
Mehmet Akif Ersoy Hall
Honorary President
Prof. Dr. A. Haluk Özen, Hacettepe University
Congress Chair
Assoc. Prof. Dr. Memed Duman, Hacettepe University
Congress Co-Chair
Assoc. Prof. Dr. Çağlar Elbüken, Bilkent University
Assoc. Prof. Dr. Gökhan Demirel, Gazi University
Organizing Committee
Gülgün Aylaz, Hacettepe University
Esma Sari, Hacettepe University
Meltem Okan, Hacettepe University
Selim Sülek, Hacettepe University
İpek Akyılmaz, Hacettepe University
Congress Topics
Bioinformatics
Biomaterials
Commercial biosensors, manufacturing and markets
Electrochemistry
Microfluidics/Lab-on-a-chip devices
Molecular biology
Nanobiotechnology
Nanomaterials and nanoanalytical systems
Natural and synthetic receptors
Next generation sequencing microRNA
Organism- and whole cell-based biosensors
Aptamer based biosensors
DNA microarray chips and sensors
Enzyme biosensors
Immunosensors
Neurosensor
Optical sensors
MicroPADs
Printed biosensors and organic electronics
Sensors to Monitor Food Quality and Safety
Single-cell detection and analysis
WEDNESDAY, OCTOBER 5, 2016, 3rd INTERNATIONAL CONGRESS ON BIOSENSORS
08:30-09:30 Registration
09:30-09:45 Opening Talk Memed Duman (Congress Chair), Hacettepe University Prof. Dr. A. Haluk Özen (Rector-Honorary President), Hacettepe University
Session Chair: Dirk Mayer
09:45-10:30 Plenary Speaker- Arben Merkoçi, Catalan Institute of Nanoscience and Nanotechnology PS0101-“Nanomaterials-based sensors for diagnostics applications”
10:30-11:00 Invited Speaker- Vural Gökmen, Hacettepe University IS0101-“Machine Vision-Tool to Monitor Food Quality and Safety During Processing”
11:00-11:15 Coffee Break
Session Chair: Arben Merkoçi
11:15-11:45 Invited Speaker- Suna Timur, Ege University IS0102-“Integration of Biomolecules to Electrochemical and Optical Systems”
11:45-12:15 Invited Speaker- Alper Kiraz, Koç University IS0103-“Optofluidic Microresonators for Bio/Chemical Sensing Applications”
12:15-12:30 Oral Presentation- Gökhan Bakan, Antalya International University OP0101-“Pattern-Free, CMOS Compatible Infrared-Absorption-Spectroscopy Surfaces for Sensing Bio-Molecule Monolayers”
12:30-12:45 Oral Presentation- Müslüm Kaan Arıcı, Middle East Technical University OP0102-“Salmonella Detection via Silica Nanoparticle based Lateral Flow Test Platform”
12:45-13:00 Oral Presentation- Nilgün Dükar, Ordu University OP0103-“miRNA Sensing Self-Propelled Hybrid Micromotors”
13:00-14:30 Lunch Break
Session Chair: Mustafa Kemal Sezgintürk
14:30-15:00 Invited Speaker- Canan Dağdeviren, Harvard University IS0104-“An ‘Unusual’ Story: The Biology Meets Its Match “
15:00-15:30 Invited Speaker- Filiz Kuralay, Ordu University IS0105-“Impact of Nanotechnology on Biomedical Sciences: Biosensing and Drug Delivery”
15:30-15:45 Oral Presentation- Murat Serhatlıoğlu, Bilkent University OP0104-“Fabrication and Characterization of Miniaturized Optical Flow Cytometry Design”
15:45-16:00 Oral Presentation- Zeynep Çağlayan, Middle East Technical University OP0105-“Dielectrophoretic Spectra of Polymorphonuclear White Blood Cells”
16:00-16:15 Coffee Break
Session Chair: Suna Timur
16:15-16:45 Invited Speaker- Humphrey Yiu, Heriot Watt University IS0106-“Surface Functionalization of Nanoparticles for Immunosensing of Biomolecules”
16:45-17:00 Oral Presentation- Rükan Genç, Mersin University OP0106-“Synthesis of Functionalized Fluorescent Carbon Nanoparticles as Artificial Enzymes and Signaling Tools for Their Use in Bioanalysis”
17:00-17:15 Oral Presentation- Selmihan Şahin, Süleyman Demirel University OP0107-“Preparation of Polypyrrole based Electrodes for Glucose 6-Phosphate Determination”
17:15-19:00 Poster Presentations Session 1
PP0101-PP0156
THURSDAY, OCTOBER 6, 2016, 3rd INTERNATIONAL CONGRESS ON BIOSENSORS
Session Chair: Haluk Külah
09:00-09:30 Invited Speaker- Dirk Mayer, Forschungszentrum Jülich IS0201-“Aptamer-based Biosensor with Electrochemical Current Rectification as Signal Amplification Strategy”
09:30-10:00 Invited Speaker- Selim Ünlü, Boston University IS0202-“Multiplexed Digital Detection of Protein Biomarkers for Cancer Diagnosis”
10:00-10:15 Oral Presentation- Hilay Şencan, Boğaziçi University OP0201-“Investigation of Protein Adsorption on Gradually Reduced Graphene Oxide Modified Surfaces by QCM”
10:15-10:30 Oral Presentation- Erhan Zor, Necmettin Erbakan University OP0202-“Paper-based Sensors as Optical Chiral Discrimination Platform”
10:45-11:00 Coffee Break
Session Chair: Selim Ünlü
11:00-11:30 Invited Speaker- Haluk Külah, Middle East Technical University IS0203-“BioMEMS and Microfluidic Devices for Lab-on-a-Chip Applications”
11:30-12:00 Invited Speaker- Mustafa Kemal Sezgintürk, Namık Kemal University IS0204-“ITO based Disposable Biosensors and New Immobilization Agents”
12:00-12:15 Oral Presentation- Ziya Işıksaçan, Bilkent University OP0204-“Point-of-Care Measurement of Erythrocyte Sedimentation Rate”
12:15-12:30 Oral Presentation- Fatma Doğan, Eskişehir Osmangazi University OP0205-“Nanopore-Integrated Microfluidic Biosensors with Single Molecule Detection Capability”
12:30-13:00 Oral Presentation- Yeliz Yavuz Çelik S0201- “Metrohm Autolab and DropSens News”
13:00-14:30 Lunch Break
Session Chair: Yıldız Uludağ
14:30-15:00 Invited Speaker- Uğur Tamer, Gazi University IS0205-“Rapid Detection Strategies for Pathogens Using Functionalized Nanoparticles”
15:00-15:15 Oral Presentation- Murat Uygun, Adnan Menderes University OP0206-“Biomimetic Carbon Dioxide Sequestration by Using Carbonic Anhydrase Attached Micromotors”
15:15-15:30 Oral Presentation- Mustafa Yorulmaz, ASELSAN Research Center OP0207-“Single-Particle Imaging for Biosensor Applications”
15:30-15:45 Oral Presentation- Kutay İçöz, Abdullah Gül University OP0208-“Cell Phone Microscopy + Image Processing: Low Cost Readout Method for BioMEMS”
15:45-16:00 Oral Presentation- Sevde Altuntaş, TOBB Economics and Technology University OP0209-“Detection of Alzheimer`s Protein on Polycarbonate Nanopillared Films by Using Surface Enhanced Raman Spectroscopy”
16:00-16:15 Coffee Break
Session Chair: Alper Kiraz
16:15-16:45 Invited Speaker- Yıldız Uludağ, TÜBİTAK BİLGEM IS0206- “MiSens Device as a New Automated Biosensing Platform based on Real-time Electrochemical Profiling (REP)”
16:45-17:00 Oral Presentation- Eda Çelik, Hacettepe University OP0210-“Glycophage based Array as an Alternative Biosensor for Pathogen Detection”
17:00-17:15 Oral Presentation- Resul Sarıtaş, Siirt University OP0211-“Detection of Micro and Nanoparticles in a Microfluidic Device Using Resistive Pulse Sensing Technique”
17:15-19:00 Poster Presentations Session 2 PP0201-PP0256
19:30 Gala Dinner
FRIDAY, OCTOBER 7, 2016, 3rd INTERNATIONAL CONGRESS ON BIOSENSORS
Session Chair: Filiz Kuralay
09:00-9:30 Invited Speaker- Urartu Özgür Şafak Şeker, Bilkent University
IS0301- “Synthetic Genetic Circuits Operated Whole Cell Biosensors”
09:30-10:00 Invited Speaker- Adil Denizli, Hacettepe University
10:00-10:15 Oral Presentation- Fatih Şen, Dumlupınar University OP0301-“Next Generation Biosensors: Near-Infrared Fluorescent Single-Walled Carbon Nanotubes”
10:15-10:30 Oral Presentation- Meltem Okan, Hacettepe University OP0302-“Molecularly Imprinted Polymer based Microcantilever Sensor for the Selective Determination of Erythromycin in Water Resources”
10:30-10:45 Coffee Break
Session Chair: Urartu Özgür Şafak Şeker
10:45-11:15 Invited Speaker- Ömür Çelikbıçak, Hacettepe University IS0303-“Mass Spectrometry in Biomedical Research”
11:15-11:30 Oral Presentation- Hasret Subak, Yüzüncü Yıl University OP0303-“Electrochemical Detection of Interaction Between Plantago Anatolica and DNA by Using Disposable Biosensors”
11:30-11:45 Oral Presentation- Mehmet Yılmaz, Sinop University OP0304-“ Thin Films of p-type Organic Semiconductors as SERS Substrates”
11:45-12:00 Oral Presentation- Gözde Aydoğdu Tığ, Ankara University OP0305-“Simultaneous Electrochemical Determination of Ascorbic acid, Dopamine and Uric Acid based on Gold Nanoparticles-Graphene oxide-Poly-(2,6-Pyridinedicarboxlic Acid) Modified Electrode”
12:00-12:15 Oral Presentation- Irmak Karaduman, Gazi University OP0306-“Acetone Gas Sensor based on ZnO Nanostructure Produced by Successive Ionic Layer Adsorption and Reaction (SILAR) Method”
12:15-12:30 Oral Presentation- Pınar Kara, Ege University OP0307-“Biosensing Strategy for Detection of Bacterial Susceptibility Against Beta Lactamases”
12:30-12:45 Oral Presentation- Dilber Ece Sezgin, Eskişehir Osmangazi University OP0308-“RNA SELEX for Green Fluorescent Protein and Application of Selected Aptamer to Optic Biosensors”
12:45-14:30 Lunch Break
Session Chair: Ömür Çelikbıçak
14:30-15:00 Invited Speaker- Arzum Erdem Gürsan, Ege University IS0304-“Nanomaterials Integrated Electrochemical Biosensors”
15:00-15:15 Oral Presentation- Günnur Güler- Ege University OP0309-''Rapid Detection of Disease Biomarkers with ATR-FTIR Spectroscopy''
15:15-15:30 Oral Presentation- Derya Koyuncu Zeybek, Dumlupınar University OP0310-“A Label-Free Electrochemical Immunosensor based on ERGO for Determination of Hemoglobin A1c”
15:30-15:45 Oral Presentation- Gülgün Aylaz, Hacettepe University OP0311-“A Novel Fiber based MALDI Probe for Selective Detection of Ciprofloxacin”
15:45-16:00 Oral Presentation- Zeeshan Rashid, Koç University OP0312-“Smart Surface based Guiding of Microdroplets Over Laser Ablated Sinusoidal Rail”
16:00-16:15 Oral Presentation- Recep Üzek, Hacettepe University OP0313-“ Functional GQDs Nanocomposite Fabricated for Direct and Rapid Detection of BPA with Paper Based Fluorescent System”
16:15-17:15 Closing and Award Ceremony
ABSTRACTS
Invited
Speakers
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Nanomaterials-based sensors for diagnosticsapplications
Arben Merkoçi1
1 CREA Research Professor & Group Leader Nanobioelectronics & Biosensors Group Catalan Institute of Nanoscience
and Nanotechnology (ICN2) Campus de la UAB 08193 Bellaterra (Barcelona) Spain& CIN2 (ICN-CSIC) Barcelona,
Catalonia, Spain
Machine Vision-Tool to Monitor Food Quality and Safety During Processing
Vural Gökmen1
1Food Engineering Department, Hacettepe University, Ankara, Turkey
Integration of Biomolecules to Electrochemical and Optical Systems
Suna Timur1
1Ege Üniversitesi, Fen Fakültesi, Biyokimya Bölümü, Bornova, İzmir, Turkey
Surface Functionalization of Nanoparticles for Immunosensing of Biomolecules
Humphrey Yiu1
1School of Engineering & Physical Sciences; Mechanical Process & Energy Engineering, Heriot-Watt University,
Edinburgh, Scotland, UK
Aptamer-based Biosensor with Electrochemical Current Rectification as Signal
Amplification Strategy
Dirk Mayer1
1Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich, Jülich, Germany
MiSens Device as a New Automated Biosensing Platform based on Real-time
Electrochemical Profiling (REP)
Yıldız Uludağ1
1TÜBİTAK BİLGEM
Synthetic Genetic Circuits Operated Whole Cell Biosensors
Urartu Özgür Şafak Şeker1
1UNAM National Nanotechnology Research Center, Bilkent University, Ankara, Turkey
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Optofluidic Microresonators for Bio/Chemical Sensing Applications
Alper Kiraz1*
Departments of Physics and Electrical-Electronics Engineering
1Koç University, Rumelifeneri Yolu, 34450 Sariyer, Istanbul, Turkey
akiraz@ku.edu.tr
Abstract
Fluids possess unique properties for designing optical
components and systems: (i) they have optically smooth
interfaces and (ii) they provide a great flexibility in shape and refractive index. Optofluidics has recently
emerged as an exciting new research field employing
these unique properties of fluids to design optical
components and systems that cannot be realized with
classical solid-state materials. Optofluidic platforms
usually exploit established design and manufacturing
principles developed within the past two decades for the
production of microfluidic chips. In this presentation, I
will present some alternative approaches we have
followed in my research group which can serve as
inspirations for future optofluidic platforms.
Microdroplets of water and other polar liquids take
almost spherical shapes when standing on a
superhydrophobic surface. With their truncated
microsphere geometry, they act as optical microcavities
hosting whispering gallery modes. I will summarize the
novel spectral tuning techniques, and organic/bio
emitting device concepts, we developed using
microdroplets that are standing on a superhydrophobic surface or trapped using different manipulation
methods. I will discuss the recent experiments we have
performed on optical spectroscopy of microdroplets
using tapered optical fibers.
I will also discuss our results on hydrogen and humidity
sensing using microdisk structures fabricated by SU-8
photoresist. The results that I will describe were partially supported by TÜBİTAK Grants No: 110T803,
112T972, and 115F446.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Nanomaterials Integrated Electrochemical Biosensors
Arzum Erdem1
1Ege University, Faculty of Pharmacy, Analytical Chemistry Department, 35100 Bornova, Izmir, Turkey
arzume@hotmail.com
arzum.erdem@ege.edu.tr
Abstract
The nanoscale materials integrated sensors based on
nanoparticles, nanowires, dendrimers, nanotubes and other nanomaterials have recently received the
considerable attention [1-6]. The development of
advanced biosensor platforms could impact
significantly the areas of genomics, proteomics,
biomedical diagnostics and drug discovery.
Electrochemical biosensors coupling the inherent
specifity of biorecognition reactions with high
sensitivity of physical transducers, present a great
promise for sequence-specific nucleic acid
detection (DNA, RNA etc.) for clinical,
environmental or forensic investigations [1-6].
An overview to nanomaterials integrated
electrochemical biosensors has been presented
herein for monitoring of spesific biomolecular
recognitions; such as, nucleic acid hybridization,
aptamer-protein or drug-DNA interactions with
their advantages and further applications.
References
1. Palecek E., Bartosik M., (2012) Chem. Rev.,
112; 3427.
2. Gao W., Wang J., (2014) Nanoscale, 6; 10486.
3. Patolsky F., Lieber C.M., (2004) Materials
Today, 8; 20.
4. Sassolas A. , Leca-Bouvier B.D., Blum L.J.,
(2008) Chem. Rev., 108; 109.
5. Ma W., Situ B., Lv, W. et al., (2016) Biosens
Bioelectron., 80; 344.
6. Erdem A., (2007) Talanta, 74; 318.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
An ‘Unusual’ Story: The Biology Meets Its Match
Canan Dağdeviren1
1Koch Institute for Integrative Cancer Research, MIT, USA
Abstract
Multifunctional sensing capability, ‘unusual’ formats with flexible/stretchable designs, lightweight
construction and self-powered operation are desired
attributes for electronics that directly interface with the
human body. Today’s electronics are stiffer by up to six
orders of magnitude compared to soft tissue. Thus,
present systems limit intimate integration with biology.
I have focused on novel microfabrication techniques
and tricks to use active piezoelectric materials and
required electronic components, which have the shape
and the mechanical properties that match with those of
human tissues, in order to allow intimate integration without any irritation and/or harm on body.
In this talk, I describe novel materials, mechanics and
device designs for emerging classes of wearable health
monitoring systems and implantable, minimally
invasive medical devices. These include a variety of
electrodes, sensors, and energy harvesting components,
with promising applications in bio-integrated electronics, such as self-powered cardiac pacemakers,
wearable blood pressure sensors, modulus sensor
patches, and brain injectrodes. The devices can be
twisted, folded, stretched/flexed and wrapped onto
curvilinear surfaces or implanted without damage or
significant alteration in operation. The fabrication
strategies and design concepts can be applied to various
biological substrates and geometries of interest, and thus
have the potential to broadly bridge the gap that exists
between rigid, boxy electronics and soft, curvy biology.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Impact of Nanotechnology on Biomedical Sciences: Biosensing and Drug
Delivery
Filiz Kuralay1
1Faculty of Art and Sciences, Ordu University, Ordu, Turkey
Abstract
Nanoscale materials have drawn great attention in
recent decades for the development of new
technologies. These materials including carbon
nanotubes, graphene, nanoparticles, nanowires and
nanostructured polymers are widely used in
biomedical, pharmaceutical, forensic, food safety,
energy storage and environmental applications due
to their excellent chemical, mechanical, electrical,
structural, optical and thermal properties. They
constitute an emerging, interdisciplinary field of
science for developing new detection methods and
scientific investigations of the materials obtained.
Nanomaterials-based methods have various
commercial and technological applications with the
advantage of eliminating the use of laborious,
expensive and complex methods. The aim of this
talk will be focusing on various nanomaterials-
based studies developed for the detection of nucleic
acids and neurotransmitters and nano/
microactuators for controlled drug release and
delivery.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
BioMEMS and Microfluidic Devices for Lab-on-a-Chip Applications
Haluk Külah1,2
1METU MEMS Center, Ankara, Turkey
2METU, Electrical and Electronics Engineering Department, Ankara, Turkey
Abstract
This presentation introduces MEMS and microfluidics technology for biomedical applications, including their applications with examples from the literature. BioMEMS related projects at METU-MEMS Center will be presented. Since the first introduction in 1970’s, MEMS technology is becoming popular in many different application areas,
including military, automotive, and consumer electronics, as it provides cheap, small, and smart sensors and actuators. This technology is especially critical for biomedical applications, resulting in a new research area shortly called BioMEMS. BioMEMS can be defined in general as “devices or systems constructed using techniques inspired from microfabrication that are used for processing, delivery, manipulation, analysis, or construction of biological and chemical entities [1].”
Application areas of BioMEMS range from diagnostics to micro-fluidics, systems for drug delivery, tissue engineering, and implantable biomedical systems. One of the most interesting application areas for this technology is the micro total analysis systems (Micro-TAS). Biological samples can be analyzed in a very small area with considerably reduced cost and time, by forming micro-fluidic channels on silicon substrate and combining them with onchip electronics. Some
examples for such applications include on-chip electrophoresis systems, polymerized-chainreaction (PCR) units, DNA sequencing chips, and complex lab-on-a-chip devices [2-6]. These kinds of systems can be incorporated with wireless electronics technology and can be implanted inside the body for real time measurement of blood chemical values. Even further, it is possible to form small reservoirs on the same chip
for storing drugs and releasing them to the body according to the analysis results. Similar systems can be used for diagnosis purpose. In this case, the technology is used to detect predefined sort of cells, viruses, bacteria, proteins, or enzymes in blood or in another liquid environment. This application is very critical for prevention of diseases as well as early detection of them. Another interesting application for BioMEMS is smart bio-implants. Combining this technology
with complex CMOS circuitry, it is possible to produce biocompatible, small, smart and esthetic implants. There are currently various BioMEMS related projects going on at METU-MEMS, including DNA electrophoresis systems [3], dielectrophoresis chips for cell seperation [4], gravimetric sensors for cancer cell detection, microvalves and pumps for lab-on-a-chip systems [5], and electrochemical sensors for bacteria and toxin detection. Figure 1-3 show pictures of some prototypes developed in our group.
Figure 1 Micro-channels and valves developed at METU-MEMS Figure 2 DEP-based cell separation chips
Figure 3 Microfluidic bacteria detection system and droplet-based drug effect analysis chips.
Figure 4 Parylene-based neural probes developed at METU-MEMS
References
[1] R. Bashir, “BioMEMS: state-of-the-art in detection, opportunities and
prospects,” Advanced Drug Delivery Rev., Vol: 56, 11, 1565-86, 2004.
[2] V.M. Ugaz et. al. “Microfabricated electrophoresis systems for DNA
sequencing and genotyping applications: current technology and future
directions,” Philos Transact A Math Phys Eng Sci.; 362: 1105-1129,
2004.
[3] S. Sukas et. al., "A parylene based double-channel
microelectrophoresis
system for rapid mutation detection via heteroduplex analysis,"
Electrophoresis J., Vol. 29, No. 18, pp. 3752-58, 2008.
[4] G. Yılmaz et. al. "A Dielectrophoretic Cell/Particle Separator
Fabricated By Spiral Channels and Concentric Gold Electrodes,”
TRANSDUCERS'07, pp. 73-76, June 2009.
[5] E. Yıldırım et. al." An Electrostatic Parylene Microvalve for
Controlling In-Plane Flow,” μTAS 2009, October 2009.
[6] A.C.R. Grayson et. al., “A BioMEMS review: MEMS technology for
physiologically integrated devices,” Proceedings of the IEEE, Volume 92,
Issue 1, pp. 6 – 21, Jan. 2004.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
ITO based Disposable Biosensors and New Immobilization Agents
Mustafa Kemal Sezgintürk1
1Namık Kemal University, Faculty of Arts and Science, Chemistry Department,
Biochemistry Division, Tekirdağ, Turkey
msezginturk@hotmail.com
1. Introduction
The development biosensors has attracted a great
deal of interest due to their high sensitivity and
selectivity, and they are being increasingly used in
many fields, such as analytical chemistry, industrial
process monitoring and control, clinical
diagnostics, environmental monitoring and security,
and food safety. Biosensors are also attractive for
pharmaceutical and biomedical analysis due to their
sensitivity (ng/mL or less) and high selectivity, and
sometimes their specificity, high benefit/cost ratio, simple use and rapidity of data collection [1].
The major advantages of biosensors over
traditional analytical methods, which will certainly
lead in the near future to their even more
pronounced use in the biomedical field, are: the fact
that analyte detection can very often be made
without prior separation; the short response times
that make possible the real-time monitoring of
biological and manufacturing processes; their ease
of use, allowing in-field or point-of-care measurements; the flexibility and simplicity of
preparation; the possibility of mass production and
low production costs; and the possibility of
miniaturization and automatization. [2].
As for the electrochemical transducer, important
advances have been recently made thanks to the
introduction of new platforms for biosensor design,
such as nanotechnological materials and
nanostructured architectures (i.e., nanoparticles,
carbon nanotubes and nanofibres, graphenes,
nanostructured surfaces, etc.), which have improved the sensitivity of the assembly [3].
2. Results and Discussion
Materials used for the electrode and supporting
substrate are usually conductive materials
exhibiting low currents in an electrolyte solution,
free of any electroactive species, over a relatively
wide potential window.
Among the most frequently used materials for the electrode and supporting substrate is indium tin
oxide, ITO) based materials. Recently the
applications of indium tin oxide(ITO) film elec
trodes have increased interest in biosensor
fabrications owing to their high electrical
conductivities, excellent substrate affinity, wide
range electrochemical working area, stable
electrochemical and physical properties and also
very low costs although i thas disposable properties.
In this study, different biosensor systems based on
ITO substrates are reviewed. In these biosensing
devices, new immobilization agents are used
successively. Especially cancer biomarkers are
prefered as the targets of these newly developed
biosensor systems.
Acknowledgement: This study was supported by
The Scientific and Technological Research Council
of Turkey (TUBİTAK) by the project number of
113 Z 678.
References
[1] Cristea C, Hârceagă V, Săndulescu R.
Electrochemical sensor and biosensors. In:
Moretto LM, Kalcher K, editors. Environmental
Analysis by Electrochemical Sensors and
Biosensors. Vol. 1 Fundamentals. 1st ed. New
York: Springer; 2014. p. 155-165.
[2] Morrison DWG, Dokmeci MR, Demirci U,
Khademhosseini A. Clinical applications of micro- and nanoscale biosensors. In: Gonsalves
KE, Halberstadt CR, Laurencin CT, 22
Biosensors - Micro and Nanoscale Applications
Nair LS, editors. Biomedical Nanostructures.
1st ed. New York: John Wiley & Sons Inc.;
2008. p. 1-10.
[3] Farré M, Kantiani L, Pérez S, Barceló D. (
2009) Sensors and biosensors in support of EU
di‐ rectives. TrAC Trends Anal. Chem.
28(2):170-185.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Mass Spectrometry Applications in Biomedical Research
Ö. Çelikbıçak1
1Department of Chemistry, Hacettepe University, Ankara
omurce@hacettepe.edu.tr
Abstract
Mass spectrometry's characteristics including
unequaled sensitivity and detection limits have
raised it to an outstanding position among the other
analytical methods for diverse applications such as;
atomic physics, reaction physics, reaction kinetics,
geochronology, all forms of chemical analysis (especially in biomedicine and ion-molecule
reactions) and determination of thermodynamic
parameters [1]. By the early 1980s, mass
spectrometry was a well-established laboratory
technique for the characterization of small organic
molecules. But larger molecules - particularly
biological ones, including proteins, DNA and
complex carbohydrates - were proving to be a
challenge. Because mass analysis relies on the
ionization and detection of species in the gas phase,
the key problem was transferring sufficient energy to these large molecules to send them into the gas
phase without destroying them [2]. Mass
spectrometry has progressed extremely rapidly
during the last three decades: production, separation
and detection of ions, data acquisition, data
reduction, etc. This has led to the development of
entirely new instruments and applications. Today,
intact analysis of the high molecular weight
compounds (e.g. proteins, peptides,
oligonucleotides, carbohydrates, synthetic
polymers, large inorganic complexes etc.) are
possible using soft ionization mass spectrometry techniques having high precision and accuracy. The
most important soft ionization techniques of mass
spectrometry are Electrospray Ionization Mass
Spectrometry (ESI-MS) and Matrix Assisted Laser
Desorption/Ionization Mass Spectrometry
(MALDI-MS) which are well-suited for
macromolecular analysis. Additionally, complexes
of these macromolecules, formed by weak
noncovalent interactions, can be followed and
complex stabilities, stoichiometries and interaction
regions can be determined using the soft ionization mass spectrometry as well. More recently, after the
genome era, proteomics and metabolomics are
becoming more popular in the many fields of
biology and medicine. In those “omics” approach,
mass spectrometric techniques are not only useful
but also nearly essential [3]. Nowadays, advances
of mass spectrometry are serving the expectation of
comprehensive coverage for those studies that focus
on complex interactions within biological systems.
References
[1] Hoffmann, Edmond De., and Vincent
Stroobant. Mass Spectrometry: Principles and
Applications. Chichester, West Sussex,
England: J. Wiley, 2007. Print.
[2] Hansell, Claire. “Enter the Matrix.” Nat Meth
(2015). doi:10.1038/nmeth.3527. [3] Setou, Mitsutoshi, and Hisao Oka.
“Biomedical Mass Spectrometry.” Anal
Bioanal Chem (2011) 400: 1827.
doi:10.1007/s00216-011-4944-0
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Multiplexed Digital Detection of Protein Biomarkers for Cancer Diagnosis
M. S. Ünlü1,2,3*, Fellow IEEE, F. Ekiz Kanik1, N. Lortlar Ünlü2,3, A. Usubütün4 and E. Ç. Seymour5
1 Electrical and Computer Engineering, Boston University, Boston, USA 2 Biomedical Engineering, Boston University, Boston, USA
3 Faculty of Medicine, Bahcesehir University, Istanbul, Turkey 4 Faculty of Medicine, Hacettepe University, Ankara, Turkey
5Aselsan, Ankara, Turkey
selim@bu.edu
1.Introduction
Due to the lack of molecular analysis devices, clinical diagnosis relied mostly on medical history and physical
examination until about a hundred years ago. In modern medicine, in vitro tests are indispensable components of clinical practice with the sensitivity of standard immunoassays measuring protein biomarkers at picomolar concentrations. This level of sensitivity is sufficient for the diagnosis of infectious diseases when clear symptoms are present, however, it falls short for the detection of proteins that are important in cancer [1].
Perhaps one of the most exciting recent technological developments in biomarker analysis is single-molecule counting or digital detection, an approach that provides resolution and sensitivity beyond the reach of ensemble measurements [2-4]. Digital detection not only provides very high sensitivity, but also has the potential of making the most advanced disease diagnostic tools available at low cost. We have developed a single molecule detection
technology and we are exploring applications in highly sensitive diagnosis assays for cervical cancer.
2.Interferometric Reflectance Imaging for Single
Particle Detection
The Interferometric Reflectance Imaging Sensor (IRIS) is a low-cost, compact and simple to use biosensing platform developed at Boston University. IRIS has demonstrated high-throughput detection and quantification of protein-protein binding, DNA-protein
binding and DNA-DNA hybridization in real-time with high sensitivity and reproducibility [5]. Recent significant advancements have allowed us to detect and identify individual captured nanoparticles [6]. This new modality of IRIS is termed single-particle IRIS (SP-IRIS). SP-IRIS shines light from an LED source on nanoparticles bound to the sensor surface, which consists of a silicon dioxide layer on top of a silicon substrate (Figure 1a).
Interference of light reflected from the sensor surface is modified by the presence of particles producing a distinct signal that is captured by a conventional CCD camera. Single molecule detection/counting is a disruptive technology and digital detection of proteins in microarray format is poised to become one of the most powerful tools in the field of biomarker detection because of its enormous potential in diagnostics. The SP-IRIS platform
allows single molecule digital detection readout for different targets on one chip/test with up to 1000 times more sensitive (at atto-molar concentration) compared to conventional fluorescence systems [7].
Figure 1 SP-IRIS detection platform. a) Optical setup
which consist of LED lighting module, imaging objective
and CCD imaging camera. b) Illustration of SP-IRIS
sensor utilized for protein and nucleic acid detection. c)
A sample image showing response from individual
nanoparticles.
3.Clinical Application
We propose to apply the SP-IRIS platform to cervical cancer which is one of the most common and high
mortality rate cancers among women worldwide due to its few early stage symptoms, poor diagnosis and treatment possibility, and low survival rates. Early and accurate detection of cervical cancer is important especially in developing countries. We will translate emerging single-molecule counting or digital detection methods to develop a highly sensitive multiplexed protein assay. This technique will enable the detection of cervical
cancer at an early stage while providing valuable information about the high-risk lesions at the first screening of the patient.
References
[1] P.R. Srinivas, P.R. et al. “Trends in biomarker research for cancer detection,”
Lancet Oncol. 2, 698–704, (2011)
[2] M. Cretich, G. G. Daaboul, L. Sola, M. S. Ünlü, and M. Chiari "Digital detection of biomarkers assisted by nanoparticles: application to diagnostics," Trends in
Biotechnology, 33 (6), 343-351, (2015)
[3] A. Yurt, G. G. Daaboul, J. H. Connor, B. B. Goldberg, and M. S. Ünlü "Single
nanoparticle detectors for biological applications," Nanoscale, Vol. 4, No. 3, pp. 715 – 726, (2012)
[4] D. Walt, “Optical methods for single molecule detection and analysis,” Anal.
Chem. 85, 1258–1263, (2013) [5] O. Avci, N. Lortlar Ünlü, A. Yalcin, and M. S. Ünlü, “Interferometric Reflectance
Imaging Sensor (IRIS)-A Platform Technology for Multiplexed Diagnostics and
Digital Detection,” Sensors 15 (7), 17649-17665. (2015)
[6] G. G. Daaboul, "High-Throughput Detection and Sizing of Individual Low-Index Nanoparticles and Viruses for Pathogen
Identification," Nano Letters, Vol. 10, No. 11, pp. 4727-4731 (2010).
[7] M. Monroe et al. “Single nanoparticle detection for multiplexed protein diagnostics
with attomolar sensitivity in serum and unprocessed whole blood,” Anal Chem 85 (7),
3698-3706 (2013).
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Rapid detection strategies for pathogens using functionalized nanoparticles
Uğur Tamer1
1Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, 06330 Ankara, Turkey
utamer@gazi.edu.tr
Abstract
The identification and the rapid detection of
bacteria and viruses have been one of the most important issues for diagnostic, environment and
food industry analysis. Many serious and even fatal
medical conditions result from bacterial or virus
infection or contamination. Additionally it is
possible to have faults by erroneously negative
tests. The created problems, however in term of
public health or economic and industrial
development, suggest the development of
alternative techniques of detection of these
microorganisms. Most accurate and reliable method
of indicating the presence of bacteria is culture
assay, but the conclusion of the culture assay require at least a period of 24 hours or more. It is
very difficult to detect these bacteria in a short time
which makes this subject very important all over
the world. Therefore, rapid antigen tests (RAT)
have been developed based on an antigen-antibody
reaction. Particularly, fast, simple and inexpensive
spot test applications based on the color change are
used for qualitative analysis of bacteria. To get
highly sensitive results in RAT test, it is necessary
to increase the number of bacteria in broth media
for at least 8 hours. However, the most important disadvantage of rapid antigen tests is low sensitivity
and low accuracy for the detection of pathogens.
Additionally it is possible to have faults by
erroneously negative tests. For quantitative
analysis, highly sensitive and accurate detection
methods are needed to reach a lower limit of
detection limits, instead of the measuring color
change.
Although optical methods such as surface enhanced
Raman Scattering (SERS) or fluorescence
measurements have been used for pathogen
detection, the construction of sensitive and reproducible substrate is still a challenge.
Especially, the paper microfluidics or microchip-
based measurement is a novel approach and will be
a powerful alternative to the expensive
conventional techniques that necessitate the
consumption of excess amount of sample and
materials. The present study aims to find out the
most proper bioactive chip preparation method to
develop rapid, sensitive and selective biosensor for
the quantitative determination of bacteria. This
presentation is mainly devoted to the tag based immunoassay technique without the need for
multiple washing process and SERS or fluorescence
labels will be placed in the system prior to analysis
(see Figure 1). In this work, we have synthesized
magnetic nanoparticles which are suitable for
immunomagnetic separation of microorganism. The surface of nanoparticles is modified with controlled
orientation of antibodies.
After immunomagnetic separation of bacteria from
matrix, labeled nanoparticles were immobilized to
the target bacteria on the surface of chip surface.
Then, SERS measurement was performed on the
test line. SEM image of the test line of lateral flow
immunoassay platform also indicated the
interaction of E.coli and gold particles with labeled
antibody (Figure 2).
Figure 1. Schematic diagram of the analytical
procedure
Figure 2. SEM image of the test line after E.coli interaction
The design, preparation and surface modification of
immunoassay platform could be useable for the
detection of of target bacteria from complex
matrices. The optimization strategies and the
analytical performance of the chip-based assays
will be presented.
Oral
Presentations
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Biochar-Metalic Nanocomposite Based Glassy Carbon Paste Electrode Glucose
Biosensors
Derya Bal Altuntaş1*, Gökçen Akgül2, Eduardo Moreno Jiménez3 and Elena Diaz 4
1 Department of Bioengineering, University of Recep Tayyip Erdogan University, Faculty of Engineering , 53100, Rize, Turkey
2 Department of Energy Systems Engineering, Recep Tayyip Erdogan University, Faculty of Engineering.. 53100, Rize, Turkey 3 Universidad Autonoma de Madrid, Department of Agricultural and Food Chemistry, Madrid, Spain 4 Universidad Autonoma de Madrid, Department of Chemical Engineering, Madrid, Spain
*Presenter: derya.balaltuntas@erdogan.edu.tr
Abstract
Biosensors are frequently used for the detection of
components such as drugs, harmful pathogens,
heavy metals or used for medical diagnoses by converting chemical and biological information
together into easily detectable signals [1]–[5]. As
reconstitution approach, a porous solid material as
conductive support or transducer is developed and
employed to the electrode surface. Novel researches
on support materials integrated with biochar [6]–[9].
Biochar is a carbonaceous material, derived from
biomass pyrolysis. For biosensor applications, some
properties of biochar may be improved by some
activations or modifications that would enhance
biochar applicability. The surface area and average
pore diameter of biochar can be developed by metal impregnation to excellent highly microporous
structures. In this work, electro-analytical properties
of metal impregnated-biochar was investigated as
support material with biochar carbon paste electrode
(BCPE). Biochar was derived from industrial tea
waste (BCTW). Biochar from tea waste was
impregnated with MgCl2 salt and calcinated. The structure contains MgO which dominates
microporosity of biochar (Figure 1-3).
The biochar has mostly micro-size particles alongside
nano ones. This simply nano-sized biochar was used with
glucose oxidase enzyme and in glassy carbon paste
electrode (GCPE) as biosensor support material contributing to the sensitivity of glucose biosensors.
Among other sensing platforms, glucose biosensors are
of special clinical and industrial significance because of
their role in monitoring blood-glucose levels in diabetes
mellitus, one of the most prevalent metabolic disorders
worldwide. Similar to other sensing platforms, glucose
biosensors have been the target to incorporate
nanomaterials, including metal nanoparticles (MNPs)
[10].
Figure 2. EDS image of Mg-impregnated biochar
Figure 3. EDS map of Mg-impregnated biochar
The electrochemical performances of The Mg-BCPE was tested in glucose biosensor transducers.
Acknowledgement: We are thankful to Universidad
Autonoma de Madrid, Department of Agricultural and
Food Chemistry and Chemical Engineering, Madrid,
Spain for the opportunity to use their laboratory facilities.
We gratefully acknowledge the financial support for
chemical analyses provided by Recep Tayyip Erdoğan
University, Scientific Research Projects Coordinator
Unit (BAP) (Project No: RTEU-2014.29.109.04.01 and
RTEU- 2015.53008.109.07.01).
References [1] R. Jain et al., Appl. Surf. Sci., 369, 151–158 (2016).
[2] M. Soler et al.., Biosens. Bioelectron. 66, 115–123
(2015). [3]H. Liu et al., Sensors Actuators, B Chem. 218,
60–66 (2015). [4]X. Wang et al., Biosens. Bioelectron.
81, 349–357 (2016).
[5] S. Han et al., Biosens. Bioelectron. 80, 265–272 (2016).
[6] D. Agustini et al., Talanta 142, 221–227 (2015). [7] A. Gevaerd et al., Mater. Sci. Eng. C 62, 123–129
(2016).
[8] P. R. Oliveira et al., Food Chem. 171, 426–431 (2015).
[9] T. M. Suguihiro et al, Bioresour. Technol. 143, 40–45
(2013). [10]A. A. Saei et al. Trends in Analy. Chem. 42,
216-227 (2013).
Figure 1. Mg-impregnated biochar
Oral Presentation – OP0203
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A label-free electrochemical immunosensor based on ERGO
for determination of Hemoglobin A1c
Derya Koyuncu Zeybek1* and M. Özge Karaşallı1
1Department of Biochemistry, Faculty of Science and Arts, University of Dumlupınar, Kütahya, Turkey
*Presenter: derya.kzeybek@dpu.edu.tr
Introduction
Diabetes Mellitus (DM) is a group of metabolic
diseases characterized by hyperglycemia affecting
about 150 million people around the world. For diagnosis and prevention of diabetes, measurement
of blood glucose value is the most commonly used
method. However, when blood glucose levels are
determined in this approach, which can fluctuate and
reflect a glucose level can be affected by the daily
diet and should be measured at regular intervals [1].
Hemoglobin A1c (HbA1c) or glycated hemoglobin
is defined as the gold standard in the diagnosis of
DM [2] The level of HbA1c reflects the average
blood glucose levels over 2-3 months and is not
affected by daily fluctuations of glucose levels. Several methods have been reported for
determination of HbA1c, such as boronate-affinity
chromatography, HPLC and capillary
electrophoresis [3-5]. Besides, electrochemical
immunosensors based on the specificity of antigen-
antibody interactions have been attracted increasing
attention owing to their significant advantages such
as simple procedure, high sensitivity, small
analytical volumes, low cost, easy miniaturization,
and rapid detection [6].
In this work, we reported a novel label-free
electrochemical immunosensor capable of sensitive detection of the DM biomarker HbA1c. The
immunosensor was fabricated based on
electrochemical reduced graphene oxide modified
glassy carbon electrode. Quantitative determination
of HbA1c was based on decreasing electrochemical
signal for Fe(CN)6-3/Fe(CN)6
-4 redox couple.
2. Experimental
2.1. Preparation of the GC/ERGO electrode
Graphene Oxide (GO) was prepared based on
modified Hummers method. 10 µl of GO (1mg/1mL ultrapure water) was dropped onto bare glassy
carbon electrode surface, and then dried at room
temperature. Subsequently, GO was
electrochemically reduced in 0.1 M KCl by cyclic
voltammetry.
2.2. Fabrication of the immunosensor
To immobilize anti-HbA1c antibody on GC/ERGO
electrode, an adequate amount of anti-HbA1c
antibody solution was dropped on the electrode
surface and incubated at 37°C (denoted as
GC/ERGO/HbA1cAb electrode). This procedure was followed by incubation with BSA% to block
nonspecific binding sites (denoted as
GC/ERGO/HbA1cAb/BSA electrode). Finally,
different concentrations of HbA1c antigen solutions
prepared in PBS (pH 7.4) were added onto
GC/ERGO/HbA1cAb/BSA electrode and incubated at 37°C (denoted as
GC/ERGO/HbA1cAb/BSA/HbA1c electrode).
2.3. Electrochemical Measurement
Electrochemical behaviors of proposed electrodes
were studied by CV and DPV in 10 mM pH 7.4 PBS
containing 5 mM Fe(CN)6-3/Fe(CN)6
-4 and 0.1 M
KCl.
HbA1c detection was performed via DPV in 10 mM
pH 7.4 PBS containing 5 mM Fe(CN)6-3/Fe(CN)6
-4
and 0.1 M KCl in the potential range from -0.1 to 0.6 V with a scan rate of 0.05 V s-1. The change or
relative change in peak current of the redox couple
was used to analyze the formation of antibody-
antigen complex.
3. Results
To characterize the fabrication process of the
immunosensor, CVs and DPVs were recorded at all
immobilization steps. According to the obtained
results, the GC/ERGO/HbA1cAB/BSA electrode
can be used for label-free detection of HbA1c.
The antibody coating time and antibody-antigen
incubation time were optimized. The inferences effects of some biomolecules were evaluated.
A linear relationship between DPV current change
and HbA1c concentration from 10 to 150 ng/mL
(correlation coefficient of 0.9999) was obtained.
4. Conclusions
In this study, we developed a novel label-free
electrochemical immunosensor for sensitive
determination of HbA1c.
5. References
[1] Pundir C.S., and Chawla S. 2014. Analytical Biochemistry 444,
47–56.
[2] Tanaka T., Kojiro I., Okochi M., Lim T-K.,Watanabe S.,
Harada M., and Matsunaga T. 2009. Analytica Chimica Acta
638 ,186–190.
[3] Tanaka T., Tsukube S., Izawa K., Okochi M.,Lim T-
K.,Watanabe S.,Harada M.,ve Matsunaga T. 2007. Biosensors
and Bioelectronics 22, 2051–2056.
[4] Little, Randie R., and Roberts, William L. 2009. Journal of
Diabetes Science and Technology 3(3), 446-451.
[5] Heli Siren , Laitinen P., Turpeinen U. and Karppinen P. 2002.
Journal of Chromatography 979, 201–207.
[6] Danilowicz C. and Manrique J.M. 1999. Electrochemistry
Communications 1(1), 22-25.
Oral Presentation – OP0310
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
RNA SELEX for Green Fluorescent Protein and Application of Selected
Aptamer to Optic Biosensors
Dilber Ece Sezgin1* and Mehmet Mutlu2
1 Department of Biotechnology and Biosafety, Eskisehir Osmangazi University, 26480, Turkey
2 Department of Bioengineering, TOBB University of Economics and Technology, 06520, Turkey
*Presenter: decesezgin@gmail.com
Introduction
There has been growing interest in identification and
development of more specific and sensitive molecular
recognition elements [1]. Aptamers have distinct
advantages of over others including enzymes and
antibodies as molecular recognition elements [2]. The
distinguished molecular recognition properties of
artificially synthesized, short, single stranded DNA or
RNA aptamers come from the in vitro selection strategy, which is, used combinatorial chemistry, called SELEX
(Systematic Evolution of Ligands by EXponential
enrichment) [3-5]. A typical SELEX procedure
fundamentally consists of repetitive cycles of nucleic
acid library preparation, selection, amplification and
isolation of ligand binding sequences [6]. At the end of
the iterative cycles successful ligand binding sequences
are selected from chemically synthesized initial
oligonucleotide library of about 1014 different sequences.
Despite the analytic potential of aptamer molecules they
could not sufficiently come into use yet. This problem summarized as “thrombin problem” [7]. Potential of the
ability of construct any aptamer for any target limited by
the focusing only a few aptamer especially thrombin
aptamer usage. However thrombin aptamer, which is the
first protein binding aptamer, selected as a therapeutic
tool at first [8], it has become the major target in
aptamer-based bioanalytic applications. Its use in mass
sensitive bioanalytical sensing systems has brought some
limitations with and there has been a growing need for
any secondary confirmation about binding.
In this study, we investigate the applicability of GFP and its aptamer as a model aptamer system for biosensor
applications with a higher reliability because it also will
provide an additional validation for the system with
giving an optical signal besides the mass change signal.
Materials & Methods
Previously described, constructed and optimized RNA
aptamer library was used in this study. Selection steps of
SELEX cycles were carried out with an avidin-agarose
matrix based affinity column. Target molecule GFP was
biotinylated with a commercial kit (Sigma). In vitro
transcribed and purified RNA library was incubated with
GFP and binding sequences were separated, collected and purified with Sephadex-G25 column. Collected RNA
molecules after each selection step were reverse
transcribed and subsequently PCR amplified. Thiolated
avidin immobilization onto gold surfaces was carried out
via simple drop-coating. In order to confirm the avidin
immobilization, surfaces were examined with FT-IR.
Poly-(A) tail addition to the 3’ end of the aptamer
molecules obtained by SELEX was envisaged would be
ineffective on secondary structure and confirmed by M-
Fold. 3’ biotinylated poly-(T) oligonucleotides
immobilized on to avidin coated gold surfaces. Then
poly-(A) tail was added final selected aptamer pool
immobilized with poly-(T) oligonucleotides on the surface. Thus, selected aptamer molecules immobilized
on to the gold surface via interaction between poly-(A)
and poly-(T) sequences. Aptamer target molecule
interaction on the gold surface has been shown by
fluorescence microscopy.
Results &Discussion
After 8 SELEX cycle final aptamer sequences analyzed
with DNA sequence analysis. Accordingly, it could be
easily seen that all sequences pass whole selection steps
successfully. Unfortunately we could not be able to
reduce the pool to one specific sequence because of the limited number of SELEX cycles. We selected a number
of better variant final sequences of previously described
sequence that binding GFP. We determined a novel; fast,
reliable, easy and cheap affinity-SELEX method based
on known the strongest non-covalent avidin-biotin
interaction that can be further used for any protein
molecule. Utilization of thiolated avidin molecules was
made the immobilization step easier. Additionally simple
poly-(A) poly-(T) interaction was made the
immobilization step more reliable because secondary
structure of aptamers was not affected. Optical observations of interactions between selected aptamer
molecules and GFP were successfully demonstrated that
selected aptamer molecules and GFP could be used as a
model system at biosensor research in terms of it permits
the dual control of immobilization. Here we report the
first application of GFP aptamer system as a model
system for biosensor studies.
References
[1] McKeague, M., et al., Int J Mol Sci 2010, 11, 4864-4881.
[2] Balamurugan, S., et al., Analytical and bioanalytical chemistry
2008, 390, 1009-1021.D
[3] Ellington, A.D.; Szostak, J.W., Nature 1990, 346, 818-822.
[4] Robertson, D.L.; Joyce, G.F. , Nature 1990, 344, 467-468
[5] Tuerk, C.; Gold, L., Science 1990, 249, 505-510.
[6] James, W., Encyclopedia of analytical chemistry 2000.
[7] Baird, G.S., Am J Clin Pathol 2010, 134, 529-531.
[8] Bock, L.C., et al., Nature 1992, 564-566.
Oral Presentation – OP0308
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Glycophage Based Array as an Alternative Biosensor for Pathogen Detection
E. Çelik1,2*
1Department of Chemical Engineering, Hacettepe University, Beytepe, 06800 Ankara, Turkey
2Institute of Science, Bioengineering Division, Hacettepe University, Beytepe, 06800 Ankara, Turkey
*Presenter: edacelik@hacettepe.edu.tr
Introduction
Printed carbohydrate microarrays (glycoarrays) have emerged in the last decade as powerful, high-throughput
tools for screening glycan-protein interactions and have
been applied in areas such as disease detection, drug
discovery and host-pathogen interaction studies.
However, glycoarray applications are still limited by the
expensive and complex methods available to synthesize
glycans or by the challenges in identifying and isolating
glycans from natural sources.
We have recently extended the power of phage display
technique for the production and selective enrichment of
phages that display N-linked glycoproteins [1] and further engineered these so called “glycophages” for use
in glycan microarray fabrication [2].
In this study, a simplified version of glycophage array
was developed with phages displaying E. coli O78 O-
antigen (a signature model molecule for a specific
pathogen), to study glycan binding proteins (GBPs) and
then optimized for specific phage production as well as
for array binding, probing and washing conditions.
Experimental
Helper phage VCSM13 (Stratagene) was produced in
E. coli TG1 and the glycophage particles were produced
in E. coli TG1ΔwaaL transformed with the phagemid pBAD-MBP4xDQNAT-CT::PglB and the plasmids
pMW07pglΔB or pMW07-O78, as described previously
[2]. For array studies, high binding, half-area 96-well
microtiter plates (Corning) were coated with 1-20x1011
glycophage particles and probed, blocked and washed
using various strategies. The absorbance in each well
was read at 492 nm after treatment with the o-
Phenylenediamine dihydrochloride (OPD) substrate
(Sigma).
Results and Discussion
Phage titers of ~2x1011 PFU per mL of culture
supernatant was obtained. When the phage preparations
were analyzed by immunoblotting, a ladder of higher molecular weight bands were detected by the anti-Ec-
OAg (O78) antiserum. The high-molecular-weight bands
were absent in the samples obtained from cells that were
not infected with helper phage, lacked the phagemid, or
lacked the O-antigen biosynthesis pathway as negative
controls, suggesting that O78 polysaccharide was
covalently linked to MBP4xDQNAT-CT fusion protein
displayed on the phage particles. After optimized array
binding, probing and washing conditions, the signal-to-
noise ratio was higher than 2.5.
Conclusion
The advantages of glycophage-based arrays presented
here, include the low cost and scalability of phage/glycan
production, which are biosynthetic processes involving
the cultivation of recombinant E. coli cells, and the ease
with which glycophages can be recovered from the
culture supernatant without laborious purification steps.
Furthermore, an array of O-antigens, which are the
signature surface molecules of gram-negative bacteria,
displayed on the phage particles provide the basis of a
high-throughput technique for pathogen detection.
References
[1] Çelik, E., Fisher, A.C., Guarino, C., Mansell, T.J., DeLisa, M.P. Protein Science., 19, (2010) 2006-2013.
[2] Çelik, E., Ollis, A.A., Lasanajak,Y., Fisher, A.C.,
Gur, G., Smith D.F., DeLisa, M.P. Biotechnology.
Journal, 10, (2015) 199-209.
Acknowledgments- Marie Curie FP7 Career Integration
Grant under REA grant agreement # 322096 and
UNESCO-L’Oréal Young Women in Science Award.
Oral Presentation – OP0210
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Paper-based Sensors as Optical Chiral Discrimination Platform
Erhan Zor1*, M. Esad Sağlam2 and Haluk Bingol3
1 Department of Science Education, Necmettin Erbakan University, Konya, Turkey
2 Institute of Science, Necmettin Erbakan University, Konya, Turkey 3 Department of Chemistry Education, Necmettin Erbakan University, Konya, Turkey
*Presenter: zorerhan@gmail.com
Introduction
Chirality, defined as the geometric property of a
structure of being non-superimposable onto its mirror
image, is a fundamental characteristic of life processes
[1]. The majority of bioactive materials and drugs are
mainly composed of enantiomers of chiral molecules.
For living systems, one enantiomer may influence
desirable property whereas the other may often displays
a different biochemical activity or may cause serious
side-effects [2]. Therefore, the development of simple
and robust sensors for discriminative sensing of enantiomers of chiral substances is enormously
important for drug discovery and pharmaceutical
industry. Within this respect, paper-based (bio)sensing
platforms which permit the performance of low-cost and
fast response with good robustness have increased great
attention for applications in diagnostics, environmental
monitoring and food safety. Cost-efficient and eco-
friendly green materials and large-scale processes are
attracting intensive research and commercial interests
because they enable fabrication of a range of disposable
devices for consumers [3].
Figure 1. As-prepared wet nanopaper. Inset is SEM
image of dried nanopaper.
With the recent advances in nanomaterials, great effort
has been devoted to the development of miniaturized
analytical platforms for paper-based optical sensing
platforms [4]. However, paper-based platforms has been
scarcely used for optical (bio)sensing applications and
even no published study exists for optical chiral
discrimination explored by paper-based systems to date.
Hence, we sought to design, fabricate, and test simple, disposable and versatile chiral discrimination platforms
based on paper. Herein, we describe nanoparticle-
embedded paper-based platforms that exhibit plasmonic
or photoluminescent properties which can be used as
optical chiral discrimination platform. We tested
different papers such as common paper, filter paper,
cellulose acetate membrane, cooking paper and
nanopaper (Figure 1) at various configurations including
spots and signs (sensor) that are printed on papers using
a filtration method or commercial inkjet printer (Figure
2). It can be seen that color changes from red to violet in
the presence of only L-enantiomer for metallic
nanoparticles and also photoluminescent quenching
effect is observed in the case of carbon quantum dot.
(1) (2) (3)
Figure 2 Nanoparticles (NPs) embedded membrane (by
filtration) for discrimination of D-/L-enantiomer (1).
Ink-jet printed enantioselective carbon quantum dot
signs (2) and spots (3) on transparent nanopaper.
Taking advantage of the inherent chirality of metallic
NPs and chiral carbon/graphene quantum dots, we
herein point out simple paper-based sensor platforms
that can be used as a convenient colorimetric probe to discriminate enantiomers of chiral molecules, which can
be a promising model and platform for discrimination of
other biologically important enantiomers of chiral drugs
and molecules.
Acknowledgements: We express our deep thanks to the
Scientific and Technological Research Council of
Turkey (TÜBİTAK) for financial support (215Z222).
4. References
[7] Wattanakit et al., Nature Commun., 2014, 3325, 1-8.
[8] Zor et al., Biosens.Bioelectron. 42, 2013, 321–325.
[9] Huang et al., ACS Nano, 2013, 7 (3), 2106–2113.
[10] Morales-Narvàez et al., ACS Nano, 2015, 9 (7),
7296–7305.
Oral Presentation – OP0202
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Next Generation Biosensors:
Near-Infrared Fluorescent Single-Walled Carbon Nanotubes
F. Sen1*
1 Sen Research Group, Department of Biochemistry, Dumlupinar University, Kütahya, Turkey
*Presenter: fatih.sen@dpu.edu.tr
Abstract
Single-walled carbon nanotube based biosensors are
particularly attractive for biomedical applications,
because they exhibit a highly efficient fluorescent
signal in a near-infrared region where there is
minimal interference from biological media.
Although single-walled carbon nanotubes have been
used as highly sensitive detectors for various
compounds, their use as in vivo biomarkers requires
the simultaneous optimization of various parameters, including biocompatibility, molecular
recognition, high fluorescence quantum efficiency
and signal transduction. Adrressed herein, a new
type of near infrared- fluorescent single-walled
carbon nanotubes sensors have been developed and
polyethylene glycol ligated copolymer stabilizes
their fluoresecent efficiency in solution, enabling
intravenous injection into mice and the selective
detection of local nitric oxide concentration with a
very low detection limit. After localization within
the organelles, it is possible to follow the transient inflammation using nitric oxide as a marker and
signalling molecule. Finally, we demonstrate that
alginate-encapsulated single-walled carbon
nanotubes can function as implantable inflammation
sensors for nitric oxide detection.
Figure 1 DNA based carbon nanotube biosensor
References
[1] Kim, J. H. et al. The rational design of nitric oxide
selectivity in single-walled carbon nanotube near-
infrared fluorescence sensors for biological detection.
Nature Chem. 1, 473–481 (2009).
[2] Zhang, J. Q. et al. Single molecule detection of nitric
oxide enabled by d(AT)15 DNA adsorbed to near
infrared fluorescent single-walled carbon nanotubes. J. Am. Chem. Soc. 133, 567–581 (2011).
[3] Heller, D. A. et al. Optical detection of DNA
conformational polymorphism on single-walled carbon
nanotubes. Science 311, 508–511 (2006).
[4] Ahn, J. H. et al. Label-free, single protein detection
on a near-infrared fluorescent single-walled carbon
nanotube/protein microarray fabricated by cell-free
synthesis. Nano Lett. 11, 2743–2752 (2011).
[5] Barone, P. W., Baik, S., Heller, D. A. & Strano, M.
S. Near-infrared optical sensors based on single-walled
carbon nanotubes. Nature Mater. 4, 86–U16 (2005).
[6] Liu, Z. et al. Drug delivery with carbon nanotubes
for in vivo cancer treatment. Cancer Res. 68, 6652–
6660 (2008).
[7] Heller, D. A. et al. Multimodal optical sensing and
analyte specificity using single-walled carbon
nanotubes. Nature Nanotech. 4, 114–120 (2009).
e-
h+
hν
e-
h+
e-
h+
hν
Oral Presentation – OP0301
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Nanopore-integrated microfluidic biosensors with single molecule
detection capability
F Dogan1,2,3*, F. Citak2, T. Albrecht3, J. B. Edel3 and M. Winterhalter2
1Nanoscience and Nanotechnology Section, Osmangazi University, Eskisehir, 26480, Turkey
2Faculty of Science and Engineering, Jacobs University, Bremen 28759, Germany
3Department of Chemistry, South Kensington Campus, Imperial College London, London, SW7 2AZ, UK
*Presenter: fdogan@ogu.edu.tr
1. Introduction
Nanopores, both solid-state and biological ones, are
excellent tools to detect single molecules with high
precision. They are being utilized in many applications
so far including DNA-RNA sensing, epigenetics, DNA-
protein interactions and even antibiotic resistance [1, 2].
Detection using nanopores has numerous advantages over conventional techniques (e.g. gel electrophoresis)
and these are label-free detection, use of low sample
volumes and the ability to extract single molecule
information. A nanopore can be either biological or
fabricated on a solid-state microchip. Biological
nanopores exists naturally and can be experimentally
inserted into artificially created lipid bilayers, allowing
the electrophysiological study of the ionic current
across. The list for their utility can also be extended to
antibiotic research [3]; searching into a global problem
faced today: Multi-drug resistance of Gram-negative bacteria.
Figure 1. Schematic of biological nanopore-based
biosensor-antibiotic permeability assay.
Antibiotic research is important, because an unfortunate
end to the golden age of antibiotic era is approaching
and the world is in urgent need of new antibiotics, new
assays and new techniques to understand the resistance
and stop it if not too late. The problem clearly
intensifies from day to day. To address the issue, a
European Union initiative has recently been launched;
‘New Drugs for Bad Bugs’ (ND4BB)-Translocation
(www.translocation.eu) Project by Innovative
Medicines Initiative (IMI) [4]. The project is devoted to understand the permeability of antibiotics to cross the
cell wall of Gram-negative bacteria and to reach their
target. As a part of the Translocation project, we have
developed an on-chip permeability assay characterizing
single biological pores-porins that exist in the outer cell
wall of Gram-Negative bacteria and are responsible for
the uptake of several hydrophilic molecules, nutrients
and antibiotics- and addressing how single antibiotic
molecules may interact with the porin.
As for solid-state nanopores, many non-porous
semiconducting and insulating material (e.g. Si, SiO2,
graphene, ploymers) can be employed for nanopore chip
fabrication. To date, there have been numerous reports
over the material selection and the sensing ability of the
solid-state nanopores. Next appears to increase its utility by constituting an engineered device which can perform
multiple tasks within the capability of a single chip.
2. Devices and Detection Concept
Here, we present compact nanopore-integrated
microfluidic devices with single molecule detection
capability. Both solid-state and biological nanopores
(single one of them) are integrated into a single
microfluidic channel for the detection of single DNA
molecules in flow and the investigation of antibiotic
permeability, respectively (Figure 1, Figure 2).
Figure 2. Schematic of the device, a photography image and representative data for detection signal.
The detection concept is simple: upon the application of
the electric field, an ionic pathway is created from the
channel to the back side of the device through a single
nanopore. As shown in Figure 2c, this is recorded as a
stable current trace due to the passage of the electrolyte
ions. Once DNA is added to the channel, DNA blocks
the pore for a certain amount of time and current blockage events are observed, referring to individual
DNA translocations. The shape of the events changes
depending on the charge, conformation and size of the
molecule inside the pore.
3. Conclusion
In conclusion, these studies demonstrate that nanopore-
integrated microfluidic sensors can be used for single
molecule detection in flow, successfully.
4. References
[1]. Miles BN et al. Chemical Society Reviews. 2012.
[2]. Dekker C. Nat Nano. 2007;2(4):209-15.
[3]. Nestorovich EM et al. PNAS. 2002;99(15):9789-94.
[4]. Kostyanev T et al. The J. of An. Chem. 2016;71(2):290-5.
Oral Presentation – OP0205
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Pattern-free, CMOS compatible infrared-absorption-spectroscopy surfaces for
sensing bio-molecule monolayers
G. Bakan1,2*, S. Ayas2, E. Ozgur2*, K. Celebi and A. Dâna2
1Department of Electrical and Electronics Engineering, Antalya International University, Antalya, Turkey
2UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
*Presenter: gokhan.bakan@antalya.edu.tr
1.Introduction
Infrared (IR) vibrational spectroscopy is one of the
widely used tools in chemistry and biology for
characterization of materials [1]. Absorption signatures
of materials due to molecular vibrations can be sensed
in the far-field signals (reflection or transmission
spectrum) when a broadband infrared light source is
used. Current infrared measurement techniques such as Fourier Transform Infrared Spectroscopy (FTIR),
however, require large amounts of molecules for
measureable absorption signals. Increasing the near-
field intensities in the vicinity of small amount of probe
molecules can result in similar absorption signals. This
technique is known as Surface Enhanced Infrared
Absorption Spectroscopy (SEIRA) and commonly uses
plasmonic surfaces for the field enhancement [2].
Depending on the vibrational bands to be enhanced, the
geometry of nano-patterns has to be tuned. Here, we
demonstrate pattern-free surfaces which can consist of CMOS compatible materials such as Al and Si and
provide large absorption signals when coated with
monolayers of biological and chemical molecules [3].
2. Results
Electric field intensity (|E|2) enhancement factor is
almost zero on the surface of a metal and increases up to
4 at a distance quarter wavelength (λ/4) away from the
surface when the metal is exposed to infrared light.
Therefore, when a thin layer of probe material, such as a
monolayer bovine serum albumin (BSA), is positioned quarter wavelength away from the surface, the
absorption signal is expected to be enhanced by a factor
of 4 compared to the absorption of a free-standing layer.
2.1. Simulations
The resonance wavelength, at which the electric field is
enhanced to its maximum, is determined by the optical
properties of the dielectric material between the metal
and the probe material. The maximum enhancement
factor of 4 can be achieved when air (n=1) is used as the
dielectric material. However, leaving an air gap between
the metal and a thin layer of probe material complicates the fabrication process. Alternatively, IR-transparent
materials can be used as the dielectric material for an
easy fabrication at the expense of the enhancement
factor. For example, enhancement factors for some of
the IR transparent materials are 3.95 for CaF2 (n=1.25),
3.7 for amorphous silicon (a-Si) (n=3.3) (Figure 1), and
3.6 for chalcogenides (Ge2Sb2Te5, n=3.6).
Figure 1 (a) Illustration of the sensor surface with
atop 5 nm PMMA layer as the probe material.
The enhancement factor at λ~5.77 µm as a
function of the vertical position is shown on top of the illustration. (b) Simulated absorption
signal of the PMMA layer.
2.2 Experiments
The surfaces are fabricated using both plasma-
enhanced-chemical-vapor-deposition and electron-beam
evaporation of a-Si on 80-nm-Al coated Si substrates.
For proof of concept experiments, the surfaces are
coated with 5 nm PMMA layer, used as the probe
material to test the sensing performance of the surfaces.
The a-Si thickness is chosen to tune the surface’s first
order resonance to be close to the PMMA’s major vibrational band at 1732 cm-1 (λ~5.77 µm). The
measured signal intensities are ~6 % after background
subtraction. The sensing performance of the surface is
preserved up to extreme angles of incidence (75°) for
both p- and s-polarizations. The surfaces are also
studied for other dielectric materials and tested with
other biological and chemical monolayers.
3. Conclusions
We propose a pattern-free, CMOS compatible surface
structure for sensing monolayers of bio-molecules using
infrared absorption spectroscopy. The surfaces can be fabricated with low cost, on large area, and can provide
large absorption signals for very thin probe materials.
Acknowledgements: This work is supported by
TUBITAK grant #114E960 and EU FP7:People-IAPP
NanoBacterPhageSERS.
4. References
[1] Kendall, C. et al., Analyst 134, 1029–45 (2009) [2] Adato, R. & Altug, H., Nat. Commun. 4, 2154 (2013). [3] Ayas, S. et al., ACS Photonics 3, 337 (2016).
2
λ (µm)
4 6 8 10
a-Si
(400 nm)
2 40|E|2/|Eo|
2
Monolayer
(b)
Al
(a)
Sig
nal
(%
)
0
-1
-2
IR light
Oral Presentation – OP0101
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Simultaneous Electrochemical Determination of Ascorbic acid, Dopamine and
Uric Acid Based on Gold Nanoparticles-Graphene oxide-Poly-(2,6-
Pyridinedicarboxlic Acid) Modified Electrode
Gözde Aydoğdu Tığ*1, Gülendem Günendi1 and Şule Pekyardımcı1
1 Department of Chemistry, Faculty of Science, Ankara University
*Presenter: gaydogdu@science.ankara.edu.tr
1. Introduction
Ascorbic acid (AA), dopamine (DA) and uric acid (UA)
play critical roles in human metabolism, central nervous
and renal systems. Abnormal concentration levels of
AA, DA and UA can cause serious health problems
such as mental illness, cancer, Parkinson’s disease,
hyperuricaemia and gout [1, 2]. AA, DA and UA
coexist in human body fluids, thus simultaneous
determination of these substances is important not only
searching their physiological functions but also
diagnosing diseases. However, the oxidation potentials of these compounds are too close to be separated at bare
electrodes for their overlapping signals.
In this study, we propose a novel and simple strategy for
simultaneous determination of AA, DA and UA based
on gold nanoparticles (AuNPs), graphene oxide (GO)
and poly(2,6-pyridinedicarboxlic acid) (P(PDCA))
modified glassy carbon electrode (GCE).The modified
electrode shows excellent selectivity, sensitivity and
reproducibility for the determination of AA, DA and
UA with lower detection limits.
2. Materials and Methods
All electrochemical measurements were carried out by using an AUTOLAB-PGSTAT 302N electrochemical
analyzer connected with a three-electrode cell stand
(Bioanalytical Systems, BAS, Inc., USA). A
conventional three-electrode system consist of the bare
or modified GCE as working electrode, a platinum wire
as counter electrode, and Ag/AgCl (3 mol L−1 NaCl,) as
reference electrode. The CVs and DPVs were analyzed
by using NOVA 11.0 software (ECO Chemie). The
AuNPs were electrodeposited on the surface of GCE
with 0.6 mmol L−1 HAuCl4 solution in H2SO4 0.5 M for
15 cycles in the potential range of 0.2 to +1.2 V and a scan rate of 100 mVs–1 [3]. A freshly prepared monomer
solution containing 0.1 mol L−1 KCl and 1.0 mmol L−1
PDCA was prepared and then mixed with GO (1 mg/1
mL) and sonicated for 1 h to form homogeneous
mixture. The P(PDCA)-GO composite film was
fabricated on the electrode surface by CV scanning of
GCE/AuNPs in the above mixture solution from 0.0 V
to +2.0 V at a scan rate of 60 mVs–1 for 10 cycles.
3. Result and Discussion
In this study, GCE/AuNPs/P(PDCA)-GO was
constructed and this electrode was used for the
electrochemical determining of AA, DA and UA for the
first time. The composite film was characterized by
scanning electron microscopy (SEM). Electrochemical
behavior of GCE/AuNPs/P(PDCA)-GO was
investigated by using CV and EIS and compared with
those of the bare GCE. Fig. 1 depicts the DPV response
of AA, DA and UA at bare GCE (a), GCE/P(PDCA)
(b), GCE/AuNPs (c), GCE/AuNPs/P(PDCA) (d),
GCE/P(PDCA)-GO (e) and GCE/AuNPs/P(PDCA)-GO
(f) electrodes. As shown in curve f,
GCE/AuNPs/P(PDCA)-GO resolved the merged voltammetric peak into three well-defined peaks. The
peak separations between AA and DA, AA and UA, DA
and UA were 161 mV, 336 mV and 175 mV,
respectively. Moreover, a remarkable increase in each
peak current was observed with comparison to the other
modified electrodes. The effect of pH and pre-
concentration time were selected as 3.0 and 2.0 min,
respectively. Furthermore, the reproducibility,
repeatability, stability and applicability of the analysis
in urine samples were also investigated. These results
showed that the proposed method is a promising tool for
simultaneous determination of AA, DA and UA in urine.
Figure 1 The DPVs responses of 100 µmol L−1 AA,
10 µmol L−1 DA and 25 µmol L−1 UA in 0.1
mol L−1 PBS (pH 3.0) at the bare GCE (curve
a) and modified electrodes (curve b-f)
4. References
[1] X. Niu, W. Yang, H. Guo, J. Ren, F. Yang, J. Gao, Talanta, 99
(2012) 984-988.
[2] G. Zhang, P. He, W. Feng, S. Ding, J. Chen, L. Li, H. He, S.
Zhang, F. Dong, Journal of Electroanalytical Chemistry, 760
(2016) 24-31.
[3] R.-S. Saberi, S. Shahrokhian, G. Marrazza, Electroanalysis, 25
(2013) 1373-1380.
Oral Presentation – OP0305
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A Novel Fiber based MALDI Probe for Selective Detection of Ciprofloxacin
G. Aylaz1*, A. Tevlek2, Ö. Çelikbıçak3 and M. Duman1
1 Nanotechnology and Nanomedicine Division, Hacettepe University
2 Department of Bioengineering, Hacettepe University
3 Department of Chemistry, Hacettepe University
*Presenter: gulgunaylaz@gmail.com
Abstract Matrix-assisted Laser Desorption/Ionization Mass
Spectrometry (MALDI-MS) has become a popular
surface-based technique to analyze peptides, proteins and
many other molecules with biological origin. Large molar
excess of a matrix, which is usually a organic acid, is used
for increasing the ultraviolet (UV) absorbing. In MALDI,
the analyte is first co-crystallized with matrix compound,
and then analyte-matrix mixture evaporates with laser.
The matrix is an important point for absorbing the laser
energy and transporting the analyte to the detector [1][2].
New generated fibers have been produced with
electrospinning technique. Electrospun fibers have already
been used in MALDI as substrates. Different polymer
solutions travel by high electric field. When polymer
solution is exposed to the electrical effect, solvent of the
solution evaporates quickly and charged polymer is jet-
transferred to the metal collector. The feed rate of polymer
solution, the distance of solution input point and collector,
the electric field range, solvent and polymer type are the
important parameters for diameter of electrospun fibers
[3].
Molecularly Imprinted Polymer (MIP) technology is a
new approach for enrichment, selective detection studies
and separation of molecules from undesired molecules.
Monomer, initiator, cross linker and template molecule
are mixed at optimum conditions for producing. After the
polymerization proses, the template molecule is washed
away with desorption solution for creating template
molecule imprinted polymer [4].
In this study, Ciprofloxacin (CPX) which is antibiotic was
imprinted. The films and electrospun fibers were
synthesized with Poly L Lactic Acid (PLLA) polymer and
they were characterized by Fourier transform infrared
spectroscopy (FTIR) and Scanning Electron Microscopy
(SEM). Some type of films and fibers were produced with
2,5-Dihydroxybenzoic acid (DHB) because to seek
whether increasing of the ionization efficiency in
MALDI-MS or not.
As a result, signal/noise ratio (S/N) of CPX on PLLA
films in MALDI was higher than PLLA fibers. By the
way, using MIP has risen the S/N ratio. DHB effect of the
S/N ratio has not hold significant for detection CPX on
films and fibers in existence MIPs.
Figure 1.MALDI-MS Spectrums of CPX on MIP modified
electrospun PLLA fiber (a) and MIP modified electrospun
PLLA fiber with %2,5 DHB Matrix.
References
[1] Harrison Alex G, “Chemical Inonization Mass
Spectrometry”.CRC Press,2nd Edition,1992.
[2] Hansell, Claire. “Enter the Matrix.” Nat Meth (2015).
doi:10.1038/nmeth.3527.
[3] Md. Abdul Awal,” Development Of Continuous Bio-Composite
Fibres”, Doctor of Philosophy
Faculty of Forestry, University of Toronto, 2012.
[4] Giuseppe Vasapollo, Roberta Del Sole, Lucia Mergola, Maria
Rosaria Lazzoi, Anna Scardino,
Sonia Scorrano and Giuseppe Mele,”Molecularly Imprinted
Polymers: Present and Future Prospective” International Journal
of Molecular Sciences,2011,12,5908-5945.
Oral Presentation – OP0311
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Rapid Detection of Disease Biomarkers with ATR-
FTIR Spectroscopy
Günnur Güler
1* and Ercüment Karasulu
1
1Department of Biosimilar Drugs, Center for Drug R&D and Pharmacokinetic Applications, ARGEFAR, Ege
University, Izmir, Turkey
*Presenter: gunnurgorucu@gmail.com
1. Introduction
Infrared (IR) spectroscopy is a molecular vibrational
spectroscopy that yields information about the
biochemical composition, bonding properties and molecular structure (and environment) of biological
macromolecules. It is a time-saving and non-destructive
technique which requires low setup and running cost.
Therefore, it is frequently used for analyzing of tissue,
cell and body fluids which composed mainly of
proteins, lipids, carbohydrates and nucleic acids (DNA,
RNA and microRNA). Any changes in these biological
macromolecules are considered to be biomarkers for
diagnosis and monitoring of some human diseases (i.e.,
cancer); therefore, IR technique can be used for rapid,
simple and label-free detection of disease biomarkers
[1-4].
2. Experimental
The current talk deals with the theoretical and
experimental aspects of attenuated total reflection-
Fourier transform infrared (ATR-FTIR) spectroscopy
for the study of synthetic nucleic acids (DNA, RNA and
microRNA), cell lines as well as tissues in the mid-IR
spectral region of 4000-700 cm-1. Measurements of the
samples were performed with a IRTracer-100 FTIR
spectrometer (Shimadzu, Japan) combined with an ATR
accessory and equipped with a DLATGS detector. A
total of 128 scans were averaged for each interferogram at 4 cm-1 resolution.
3. Results
FTIR enables to follow the proteomic, lipidemic and
metabolic changes in real samples (i.e., cell, tissue,
body fluids) induced by diseases or drug treatment. On
the basis of the FTIR data of rat tissues (Fig. 1), a peak
of the protein amide I band can be seen around 1650
cm-1 and the amide II band appears around 1550 cm-1.
Lipid CH2 and CH3 signals appear between 2800 and
3000 cm-1 region while lipid ester carbonly groups are
detected around 1740 cm-1. Nucleic acid signals arising
from base, sugar and phosphate molecules are detected in the 1800-800 cm-1 region. Therefore, this technique
can be used for deciphering of disease biomarkers.
ATR-FTIR is a well-established tool for fast, label-free
and cost-effective detection of biomolecular targets (i.e.
nucleic acids) and requires a small amount of sample (a
few µl) without particular sample preparation. With
tracking of IR spectral changes, it is possible to observe
alterations in the molecular structure as well as
expression level of biological macromolecules in real
samples. For instance, IR spectra provide fingerprint-
like signatures of nucleic acids originating from base,
sugar and phosphate groups. Thus, the ATR-FTIR
technique as a high-sensitive optical biosensor can be a potential alternative tool which paves the way for the
rapid, simple and label-free detection of disease
biomarkers in early clinical diagnosis and biomedical
research area.
Figure 1: ATR-FTIR absorbance spectra of rat tissues
(unpublished data).
4. References
[1] Güler, G., Gärtner, R.M., Ziegler, C. and Mäntele,
M. (2016). “Lipid-Protein Interactions in the Regulated Betaine Symporter BetP Probed by Infrared
Spectroscopy.” The Journal of Biological Chemistry
291(9): 4295–4307.
[2] Kaplan, M., Kılıc, T., Guler, G., Jihane, M., Amine,
A., Ozsoz, M. “A novel method for sensitive microRNA
detection: electro polymerization based doping.”
Biosensors and Bioelectronics, in Press, accepted
manuscript,
http://dx.doi.org/10.1016/j.bios.2016.09.050.
[3] Movasaghi, Z., Rehman, S. and Rehman,I. (2008).
“Fourier Transform Infrared (FTIR) Spectroscopy of
Biological Tissues.” Applied Spectroscopy Reviews 43(2): 134–79.
[4] Banyay, M., Sarkar, M. and Gräslund, A. (2003). “A
Library of IR Bands of Nucleic Acids in Solution.”
Biophysical Chemistry 104(2): 477–88.
Oral Presentation – OP0309
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Detection of Interaction between Plantago Anatolica and
DNA by Using Disposable Biosensors
Hasret Subak1,2*, Abdullah Dalar3 and Dilsat Ozkan-Ariksoysal1*
1*Ege University, Faculty of Pharmacy, Analytical Chemistry Department, Izmir, Turkey
2Yuzuncu Yil University, Faculty of Pharmacy, Analytical Chemistry Department, Van, Turkey 3Yuzuncu Yil University, Faculty of Pharmacy, Pharmaceutical Botany Department, Van, Turkey
*Presenter: ecz.hasrets@gmail.com
Introduction
Plantago anatolica is an endemical and ethnomedical
traditional folk medicine used in eastern anatolia for
analgesic purposes. In this study, the plant extract (as
lyophylisated powder) was prepared in different
solvents such as n-hekzan, acetone, ethanol, methanol or
pure water.
There has still been groving interest in studying the
recognition and quantification of the compound-DNA
interactions by using electrochemical biosensors
because they give good information about the
interaction mechanism of the drug and DNA with their fast, simple and cost-effective methodologies.
In this study, the electrochemical behavior of the plant
extract was monitored and the effect of this extract on
DNA was investigated by using biosensor technology.
The interaction mechanism of the extract was also
studied and evaluated with bare or nanomaterial
modified disposable carbon electrodes by using
differential pulse voltammetry (DPV). Thus, the optimal
experimental parameters were determined and obtained
results showed that newly-developed biosensor could be
used for the rapid, cost effective and sensitive detection
of plant extract–DNA interaction.
Figure 1 Schematic illustration of the
electrochemical sensor for the detection of
Plantago anatolica and DNA interaction.
References
[1] Ozkan-, D. Karadeniz-,H. Erdem, A. Mascini,M.
Ozsoz, M. Journal of Pharmaceutical and Biomedical
Analysis 35 (2004) 905.
[2] E. Palecek, M. Bartosik, Chemical Reviews. (2012),
112, 3427.
[3] D. Ozkan-Ariksoysal, B. Tezcanli, B. Kosova, M.
Ozsoz, Anal. Chem. (2008) 80, 588.
[4] Ceren Sengiz, Gulsah Congur, Ece Eksin, Arzum
Erdem, Electroanalysis 2015,27, 1855 –1863.
[5] F. Lucarelli, G. Marrazza, A. P. F. Turner, M.
Mascini, Biosensors & Bioelectronics. (2004), 19, 515.
[6] Y.U. Kayran, D.Ozkan-Ariksoysal, B.Tezcanli, B.
Kosova, Mehmet Ozsoz, Electroanalysis (2013), 25, 12,
2668.
Oral Presentation – OP0303
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Impedimetric Immunosensor Based on Gold Nanoparticles
Functionalized Screen-Printed Gold Electrode for Carcinoembryogenic Antigen
(CEA) Tumor Marker Detection
Ş. Sultan1*, Ç. K. Rabia1 and K. Merve2
1 Department of Bioengineering, Yıldız Technical University, İstanbul, Turkey
2 Department of Medical Biology, S¿leyman Demirel University, Isparta, Turkey
*Presenter: sultan9019@gmail.com
Abstract
Impedimetric immunosensors are constructed with
antibody immobilization of working electrode and their
working principle is that occuring a correlation between
antigen concentration and obtained resistance after an
electrochemical Ab-Ag interaction. EIS is generally used to characterize these type detections in biosensor
applications [1]. Electrochemical impedimetric
biosensors have significant advantages for sensitive
detection of cancer biomarkers which are being smaller,
faster, more sensitive, cheaper devices, without
radiation hazards, allowing label-free, concurrent
detection, simple production, less time consuming, rapid
detection, having longer shelf life, and not complicated
procedure. These properties will substantially get easier
early dianostic of cancer at beginning phases.
Carcinoembryogenic antigens which are cell surface
glycoproteins [2] are used as an important biomarker in human serum associated with colorectal, lung, breast
cancer and ovarian carcinoma [3, 4]. CEA
quantification analysis with electrochemical impedance
spectroscopy promotes early diagnosis of cancer which
is crucial for the successful treatment of the disease and
increases health standards of people[5]. The gold layer
has various advantages during immobilization process
thereby the easy adsorption of biomaterials relates to
hydrophobic and thiol–gold interactions. In recent years,
gold nanoparticles (AuNPs) are commonly used to
enhance more sensitive electrochemical immunoassay for immobilization of antibody. AuNPs provide strongly
adsorbtion of antibody on working electrode during
immobilization due to its large specific surface area,
good biocompatibility, surface free energy of nanosized
particles [6, 7]. AuNPs facilitate electron transfer
between redox proteins and electrode surfaces, provide
effective mass transport in electrochemical biosensor
applications as making closer redox protein
(monoclonal CEA antibody) to the electrode via
nanosized structure. In the other words, AuNPs is a
desirable intermediator for immobilization of antibodies
[8]. In this study, the gold electrode is modified with thiol and AuNPs to develop an impedimetric biosensor
to detect CEA as an important cancer biomarker.
References
[1] M.I. Prodromidis, Impedimetric immunosensors-A
review, Electrochimica Acta, 55 (2010) 4227-4233.
[2] M. Taheri, U. Saragovi, A. Fuks, J. Makkerh, J.
Mort, C.P. Stanners, Self recognition in the Ig superfamily - Identification of precise subdomains in
carcinoembryonic antigen required for intercellular
adhesion, Journal of Biological Chemistry, 275 (2000)
26935-26943.
[3] X.L. Li, R. Yuan, Y.Q. Chai, L.Y. Zhang, Y. Zhuo, Y.
Zhang, Amperometric immunosensor based on toluidine
blue/nano-Au through electrostatic interaction for
determination of carcinoembryonic antigen, Journal of
Biotechnology, 123 (2006) 356-366.
[4] J. Wu, J. Tang, Z. Dai, F. Yan, H. Ju, N. El Murr, A
disposable electrochemical immunosensor for flow
injection immunoassay of carcinoembryonic antigen, Biosensors & Bioelectronics, 22 (2006) 102-108.
[5] J. Wang, Electrochemical biosensors: Towards point-
of-care cancer diagnostics, Biosensors & Bioelectronics,
21 (2006) 1887-1892.
[6] S.Y. Xu, X.Z. Han, A novel method to construct a
third-generation biosensor: self-assembling gold
nanoparticles on thiol-functionalized poly(styrene-co-
acrylic acid) nanospheres, Biosensors & Bioelectronics,
19 (2004) 1117-1120.
[7] D. Hernandez-Santos, M.B. Gonzalez-Garcia, A.C.
Garcia, Metal-nanoparticles based electroanalysis, Electroanalysis, 14 (2002) 1225-1235.
[8] J.M. Pingarron, P. Yanez-Sedeno, A. Gonzalez-
Cortes, Gold nanoparticle-based electrochemical
biosensors, Electrochimica Acta, 53 (2008) 5848-5866.
Poster Presentation – PP0242
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
(𝑎𝑑𝑠)
Acetone gas sensor based on ZnO nanostructure produced by
Successive ionic layer adsorption and reaction (SILAR) method
Irmak Karaduman1*, Tuğba Çorlu1, Memet Ali Yıldırım2, Aytunç Ateş3 and
Selim Acar1
1 Department of Physics, Science Faculty, Gazi University, Ankara, Turkey 2Department of Electric Electronics Engineering, Engineering Faculty, Erzincan University, Erzincan, Turkey 3Department of Material Engineering, Engineering and Natural Sciences Faculty, Yıldırım Beyazıt University,
Ankara, Turkey
*Presenter: irmak.karaduman@gazi.edu.tr
Abstract
With the rapid development of industrialization and
urbanization in the past few decades, environment
pollution caused by the volatilization of hazardous
gases has become an important issue. Acetone, as a
widely used solvent in industry and laboratory, can
volatilize easily and affect human health when its
concentration is higher than 173 ppm [1]. Although
the study on acetone sensor is necessary, the present
reported acetone sensors have suffered from some
disadvantages, such as poor selectivity, inadequate sensitivity [2]. Therefore, it is highly desirable to
develop high performance sensors for rapidly
selective detection of acetone [3].
Among various metal oxide semiconductor (MOS)-
based gas sensing materials studied so far, ZnO,
as a nontoxic, inexpensive and wide-band-gap II-VI
compound semiconductor, has been proved to be
one of the promising materials for gas sensors [4].
It's well known that the properties of ZnO depend
highly on its nanostructures, including crystal size,
orientation and morphology. As a consequence,
ZnO nanocrystals with highly controlled
microstructures have been investigated extensively in recent years.
The traditional gas sensors using semiconductor oxides detect an objective gas in air from a
change in current caused by the adsorption and/or reaction of gases. When the sensors are exposed to air, oxygen molecules adsorbed on the surface
would be ionized to O2−, O−or O2− by capturing free
electrons from the conduction band which causes a depletion layer and a potential barrier to charge
transport is developed. The possible reactions are expressed as follows [4];
𝑂2(𝑔𝑎𝑠) + 2𝑒− → 𝑂− (1)
The acetone gas sensing mechanism of sensing
surface can be explained by
[5]:
𝐶𝐻3𝐶𝑂𝐶𝐻3(𝑔𝑎𝑠) + 8𝑂− → 3𝐶𝑂2(𝑔) + 3𝐻20 + 8𝑒− (2)
In this study, ZnO nanostructure is grown by
Successive ionic layer adsorption and reaction
(SILAR) method and investigated its acetone gas
sensing properties. The acetone sensing properties of
the ZnO nanostructure was measured at different
operating temperatures and depending on different
concentrations. Gas sensing measurements showed
the good acetone sensing performance of such
sample at low operating temperature. The sample
showed a fast response and recovery times,
excellent repeatability, and great potential for practical applications.
Figure 1 XRD pattern of ZnO nanostructure
produced by SILAR method
References [1] L.F. da Silva , A. C. Catto , W. Avansi Jr. , L. S.
Cavalcante ,V. R. Mastelaro , J. Andres , K. Aguir , E. Longo, Journal of Alloys and
Compounds 683, (2016) 186-190 [2] D. Chen, L. Ge, L. Yin, H. Shi, D. Yang, J. Yang, Sens.
Actuators B Chem. 205 (2014) 391-400 [3] A.M. Diskin, P. Spanel, D. Smith, Physiol. Meas. 24 (2003) 107–119. [4] P. P. Sahay, Journal Of Materials Science 40
(2005) 4383 – 4385 [5] W. Ping, T. Yi, H.B. Xie, F.R. Shen, Biosens.
Bioelectron. 12 (1997) 1031–1036.
Oral Presentation – OP0306
Acknowledgements: This work was supported by the TUBITAK (Grant 115M658) and Gazi University
Scientific Research Fund under Project No:05/2015-09.
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Cell Phone Microscopy + Image Processing: Low Cost Readout Method for
BioMEMS
Kutay İçöz1*
1 Department of Electrical and Electronics Engineering, Abdullah Gül University, Kayseri, Turkey
*Presenter: kutay.icoz@agu.edu.tr
1. Introduction
According to data from World Bank approximately 7
billion cell phones are being used worldwide.
Advancements in micro fabrication technology enable
integrating various sensors in cell phones. Technical
features and extensiveness make cell phones a tool for
telemedicine.
Micro cantilevers are used to detect and measure
proteins, cells and DNA using two operation modes: resonant mode and static mode. Common techniques of
signal readout from cantilevers are measurement of
changes in laser intensity, position, or piezoresistance
(Table 1).
In this study we investigate cell phone microscopy and
image processing as an alternative readout method for
micro cantilevers. This approach has limitations
compared to conventional sensitive methods but
provides low cost, fast and mobile measurements and
can be considered as a first step analysis for micro
cantilevers.
2. Cantilevers
Micro/nano cantilevers, are mostly fabricated from
silicon, silicon oxide and silicon nitride, have been
designed and used as label-free biomolecular detectors.
Cantilever transducers convert biological signals into
mechanical deflections that can be detected using
optical, electrical and magnetic methods [1].
Table 1 Comparison of cantilever signal readout
techniques
Sensor
Type
Meas
ured
Quan
tity
Resolut
ion
Interferometry
Laser Intens
ity
0.01 Å
Optical Lever
Laser Positi
on
0.1 Å
Piezoresistive
Resistance
0.1 Å
Numerous biosensor systems based on surface
functionalized cantilevers have been implemented for
detection of various biological targets such as bacteria,
virus, proteins, DNA/RNA and cells [2], [3].
3. Cell Phone Microscopy
Low cost spherical lenses are integrated with cell
phones to develop portable microscopes [4]. These
systems can provide a resolution on the order of 1 to
10 μm. The cost of a single spherical ball lens is
less than 10 cents. 100X magnification can be
reached using a ball lens of 3.5 mm in diameter.
In this work we discuss using cell phone microscopy
+ image processing as a new readout method for cantilevers not replacing the existing ones but a
complementary low-cost, fast and portable
alternative (Figure 1). Existing measurement
methods for cantilevers provide detection of single
bacteria and virus or cell measurements such as
weighing. Cell phone microscopy can’t reach to
sensitivities for detecting viruses and can’t provide
weighing for any cell type however its current
capability is sensitive enough for detecting most of
the cell types and can be improved for bacteria.
Image processing can also provide shape and size information of each cell.
Figure 1 Left: Microcantilever imaged by optical
light microscope, Middle: Spherical Ball Lens
attached to cellphone Right: Microcantilever
imaged by the cellphone. Scale bar 100 μm.
4. References
[1] S. K. Vashist, “A Review of Microcantilevers for Sensing
Applications A Review of Microcantilevers for Sensing
Sandeep Kumar Vashist,” J. Nanotechnol. Online, pp. 1–16,
2007.
[2] K. S. Hwang, S.-M. Lee, S. K. Kim, J. H. Lee, and T. S.
Kim, “Micro- and nanocantilever devices and systems for
biomolecule detection.,” Annu. Rev. Anal. Chem. (Palo Alto.
Calif)., vol. 2, pp. 77–98, 2009.
[3] H. Etayash, K. Jiang, S. Azmi, T. Thundat, and K. Kaur,
“Real-time Detection of Breast Cancer Cells Using Peptide-
functionalized Microcantilever Arrays,” Sci. Rep., no.
August, pp. 1–13, 2015.
[4] Z. J. Smith, K. Chu, A. R. Espenson, M. Rahimzadeh, A.
Gryshuk, M. Molinaro, D. M. Dwyre, S. Lane, D.
Matthews, and S. Wachsmann-Hogiu, “Cell-phone-based
platform for biomedical device development and education
applications,” PLoS One, vol. 6, no. 3, 2011.
Oral Presentation – OP0208
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Thin Films of p-type Organic Semiconductors as SERS
Substrates
Mehmet Yilmaz1,2, Dilek Ozden1, Hakan Usta3 and Gokhan Demirel1*
1Bio-inspired Materials Research Laboratory (BIMREL) Department of Chemistry, Gazi University, Ankara, Turkey
2Department of Bioengineering, Sinop University, Sinop, Turkey 3Department of Materials Science and Nanotechnology Engineering, Abdullah Gül University, Kayseri, Turkey
*Presenter: nanobiotechnology@gmail.com
1. Introduction
Since its discovery in 1974, surface-enhanced Raman
spectroscopy (SERS) has arisen as a powerful and
sensitive vibrational spectroscopic method providing the
detection of various molecules at ultra-low
concentrations. Numerous studies have been performed to
fabricate novel SERS platforms for different applications
covering chemistry, physics, medicine, and biology.
Despite of attempts in this research field, the present SERS platforms still have some drawbacks such as
stability and reproducibility limiting their practical
applications. Small organic semiconductors, with their
facile film deposition on flexible plastic substrates and
compatibility with low-cost and large-area
manufacturing/direct-write printing technique, exhibit
exceptional charge transport/light manipulation properties
and excellent contact formation with metals such as Au
and Ag in various optoelectronic devices. In this study, to
employ the advantages of these materials as SERS
platform, thin layer of p-type organic semiconductor (2,7-
dioctyl[1]benzothieno[3,2-b]-[1]benzothiophene,C8 BTBT) was deposited through oblique angle physical
vapor deposition (PVD) technique. The resultant organic
thin film with conformal thin layer of gold (32 nm)
exhibited remarkable SERS performances in terms of
enhancement (≈108), stability (>90 days), and
reproducibility (RSD < 0.14).
2. Results and Discussion
SEM images (Figure 1) depict that the film morphologies
depend on dramatically the deposition method and the
deposition angle, α. For vapor-deposition at α = 10o 2D
microstructures with highly interconnected plate-like grains are observed (Figure 1 c,d). For the case of 90o
deposition angle, high density arrays of vertically aligned
ribbon-like micro-/nanostructures, which are highly
favorable for SERS applications, were detected (Figure 1
a,b) as a result of π–π stacking interactions between the
planar benzothieno[3,2-b]-[1]benzothiophene aromatic
cores and van der Waals interactions between lipophilic
alkyl chains at the molecular termini and also variations
in film-growth mechanisms due to different deposition
thermodynamics/kinetics and shadowing effects.
SERS activity of these films was evaluated by using
methylene blue (MB) as the Raman reporter molecule (Figure 2). Due to its 3D ribbon-like micro-
/nanostructures, gold-coated C8-BTBT films fabricated at
α = 90o exhibit a remarkable increment of the SERS
signal intensities relative to that of the smooth gold film
as a result of the tip-focusing, cavity resonances and
antenna effects. Interestingly, although C8-BTBT thin-
films deposited at α = 10o does not show any obvious 3D
morphology, a dramatic enhancement in the SERS signal
is also observed, possibly due
to formation of charge transfer
mechanisms.
Figure 1 Top-view and cross-sectional SEM images of
C8-BTBT films fabricated by vapor deposition at a,b) α =
90° and vapor deposition c,d) at α = 10° [1].
Figure 2 SERS spectra of MB on Au-coated C8-BTBT
films fabricated at a) α = 90° and b) α = 10°, and of c) a
smooth gold film on silicon [1].
Two feasible routes for charge transfer may occur upon laser excitation, which are either from C8-BTBT/gold
substrate to adsorbed MB molecule or from MB molecule
to C8 BTBT/gold substrate. As shown in Figure 3, the
highest occupied molecular orbital (HOMO) and lowest
unoccupied molecular orbital (LUMO) energy levels of
C8-BTBT molecule, the work function of the gold as well
as the HOMO and LUMO energy levels of MB exhibit
proper characteristics to create charge transfer complexes
and the resultant SERS effect.
Figure 3 Schematic representations for possible charge-transfer mechanisms (a and b) between MB and the Au/C8-BTBT film [1]. References
[1] Yilmaz et al. Adv. Funct. Mater. 2015, 25, 5669–
5676.
Oral Presentation – OP0304
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Salmonella Detection via Silica Nanoparticle based Lateral
Flow Test Platform Müslüm Kaan Arıcı1*, Onur Bulut1,2, Oya Akça3, Meral Yücel1 and Hüseyin Avni
Öktem1,2,4
1Department of Biological Sciences, Middle East Technical University, Ankara, Turkey
2 Faculty of Agriculture and Natural Sciences, Konya Food & Agriculture University, Konya, Turkey 3 Department of Molecular Biology and Genetics, Harran University, Şanlıurfa, Turkey
4 Nanobiz NanoBioTechnological Systems R&D Limited, Ankara, Turkey
*Presenter: m.kaanarici@gmail.com
1. Introduction Target-responsive nanodevices and nanostructures
based on mesoporous silica nanoparticles (MSN) have been used for different purposes such as controlled drug
delivery, diagnostic, sensing, and biomedical imaging.
Unique features of MSNs provide advantages including
large surface area, controllable particle and pore size, and
modifiable surface over other systems.
In the present study, we report a target-responsive
oligonucleotide-capped MSN based system immobilized
on lateral flow test platform to detect Salmonella
enterica. In the presence of PCR-amplified target
sequence, the oligonucletide caps on the surface of MSNs
hybridize with the complementary target sequence which
results in opening of the pores and the release of previously loaded 3,3',5,5'-Tetramethylbenzidine
(TMB), a chromogen molecule. Released TMB
molecules are subjected to a redox reaction catalyzed by
horse radish peroxidase (HRP) with the presence of H2O2
and yield a blue colored product for detection.
2. Materials and Methods Genomic DNA isolated from pre-enriched Salmonella
enterica (typhimurium, enteritidis, and infantis)
cultures was used as template DNA. Primers
selectively amplify a 284 base-pair Salmonella specific
region were used in PCR, and the resulting amplicons
were applied as the target [1].
The external surface of TMB-loaded MCM-41
mesoporous silica nanoparticles was functionalized with
(3-Aminopropyl) triethoxysilane, then separately capped
with single-stranded oligonucleotides (Probes 1 and 2)
that are complementary to the target amplicon. Components of the lateral flow strips (sample pad,
nitrocellulose card, and backing pad) were placed on an
overlapping order. Prepared MSNs and HRP were
immobilized on the strip, 4 mm and 6 mm away from the
sample pad, respectively (Figure 1). Pre-denatured target
amplicons were mixed with H2O2, then applied to lateral
flow strips.
Figure 1 Schematic representation of a MSN-based lateral
flow strip.
3. Results and Discussion The lateral flow and MSN platform developed in this
study triggers the chromogen molecule release only in
the presence of target sequence. When the denaturated
target amplicon is applied to the sample pad, it
migrates along the strip and reaches the
oligonucleotide capped MSNs. Pore opening occurs
by a displacement reaction in the presence of a
target complementary strand. This results in
hybridization of the two oligonucleotides, the
uncapping of the pores, and release of the entrapped
TMB molecules. Released TMB is oxidized through
H2O2/HRP reaction, yielding a blue color.
Additional control experiments such as using uncomplementary target DNA, capping the MSN
surface with uncomplementary probes were also
conducted and verified the accuracy of the platform
(Figure 2).
4. Conclusions
MSN-based lateral flow test platform developed in
this study can be reckoned as rapid, accurate and
cost- effective systems that can be utilized in
laboratory and field or point- of-care environments.
References
[1] Rahn, K., et al. "Amplification of an invA gene sequence of
Salmonella typhimurium by polymerase chain reaction as
a specific method of detection of Salmonella." Molecular
and cellular probes 6.4 (1992): 271-279.
Figure 2 Visualization of MSN-
based lateral flow strips under microscope. The 284 base-pair target sequence,
uncomplementary control DNA, and only H2O2 were
applied to the strips 1, 2, and
3, respectively.
Oral Presentation – OP0102
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Molecularly Imprinted Polymer Based Microcantilever Sensor for the
Selective Determination of Erythromycin in Water Resources
M. Okan1*
, Esma Sari2 and M. Duman
1
1 Department of Nanotechnology and Nanomedicine, Institute of Science, Hacettepe University, Ankara,
Turkey 2Department of Chemistry, Faculty of Science, Hacettepe University, Ankara, Turkey
*Presenter: okanmelt@gmail.com
Abstract
Erythromycin (ERY) is a class of antibiotic that is
suggested as one of the priority drinking water
contaminants at latest European Union Water Framework Directive (EU-WFD). The main goal of this study is to
develop molecularly imprinted polymer (MIP) based
microcantilever sensor for the selective determination
ERY in water resources. ERY imprinted polymeric
nanoparticles (MIP-NPs) were synthesized with
miniemulsion polymerization and their size was measured
to be 40±10 nm with high monodispersity.
Figure 5 Schematic representation of ERY imprinted
polymeric nanoparticles.
The immobilization of MIP-NPs on the microcantilevers
was accomplished by EDC/NHS activation, which
provides monolayer covalent binding. The validation of
microcantilever sensor was performed in air for a
concentration range of 0.68- 67.94 µM, employing the
dynamic sensing mode. Binding experiments showed that decrease in frequency
was observed as the MIP-NPs were exposed to the
template molecule. Results show that air studies
performed with a cantilever that has a resonance
frequency of 150 kHz works with 96% accuracy. The
detection limit and the sensitivity of the sensor were
determined as 1 µM and 1.58 Hz/pg, respectively. The
control studies of MIP-NPs were carried out with
competing agent Spiramycin (SPI) and non-imprinted
polymeric nanoparticles (NIP-NPs). Namely, 8 fold and 3
fold lower binding affinities were observed, respectively.
Reusability studies showed that the sensor system can be
used up to 3 times. The sensor system developed is low-
cost and is easily applicable by the user. This ERY specific MIP-NPs based nanosensor has the potential to be
a pioneer in the microcantilever mass sensing via
molecular imprinting technology, as it is one of its very
first examples.
Acknowledgement: This study was supported by The
Scientific and Technological Research Council of Turkey
(TÜBITAK). Project No: 113Z222.
Oral Presentation – OP0302
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Fabrication and Characterization of
Miniaturized Optical Flow Cytometry Design
S. Murat1,2*, O. Bülend1,2, E. Çağlar1,2, B. Necmi1,2 and S. E. Mehmet3
1 UNAM - National Nanotechnology Research Center, Bilkent University, Ankara, Turkey
2 Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey 3 Department of Electrical and Electronics Engineering, Izmir Katip Celebi University, Izmir, Turkey
*Presenter: m.serhatlioglu@bilkent.edu.tr
1.Introduction
Flow cytometry (FC) is used in the diagnosis and
monitoring of various diseases by inspecting, counting
and sorting the particles, cells and/or tissues which are
driven from patient. Optical flow cytometers use side
scattered light (SSC), forward scattered light (FSC) and
also fluorescence light (FL) to detect physical and chemical characteristics of flown particles. It is a
technique where cellular parameters are extracted using
a focused beam of light while they are in a fluid stream.
Examples to such parameters are cell size, granularity,
DNA content, counting of cells with specific antibody,
and protein content.
Commercial FC’s include bulk optics, which cause
alignment issues, require large amount of sample
volume and are expensive to buy and maintain.
Miniaturization of such microfluidic systems and
combining fluidic, acoustic and fiber optical components on the same glass chip is essential.
In this study, we used femtosecond laser
microfabrication which is a maskless flexible and
simple technique for concept of lab-on-a-chip
miniaturized devices and enables rapid prototyping, 3D
microstructuring into fused silica [1].
2.Experimental Details
Fabrication of miniaturized optofluidic FC microchip
starts with, CAD design and followed by the
femtosecond laser irradiation step through high precision automated XYZ stage on the one face of two
fused silica samples at very high accuracy in 3D.
Radiated samples are then immersed into HF solution in
order to develop the microchannel. Finally developed
surfaces are bonded to each other with fusion bonding
using no adhesive layer using thermal annealing for 7
hours in high temperature furnace at 650°C. The inlet
tubings are placed at last. Fabrication steps are
illustrated in figure 1.
Figure 1 Femtosecond laser fabrication steps of FC
Solidworks design and camera images of fabricated chip
can be seen in figure 2 in detail. Laser source and
optical fibers are placed through fiber slots which are at
the same size fibers so that it holds fiber tightly.
Figure 2 Fabricated FC chip, a. illustrative design,
b. camera image general, and c. closer lookup
3.Conclusion
We were able to focus 6µm polystyrene beads with 3D
hydrodynamic focusing using only one sheath fluid inlet
and one sample inlet. While focused particles passing
through laser light interrogation region, we measured FSC and SSC signals with 5 mW optical power and 405
nm wavelength of blue laser (figure 3).
In future work, we are going to add FL measurement
with fluorescence dye labeled particles and we will
improve on the signal processing capabilities with very
fast signal processing through LabVIEW FPGA.
Figure 3 FSC and SSC signals obtained by
oscilloscope.
4.References
[1] R. Osellame et al, Opt. Express 17, 8685-8695 (2009).
Oral Presentation – OP0104
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Biomimetic Carbon Dioxide Sequestration by Using Carbonic Anhydrase
Attached Micromotors
Murat Uygun1,2*, Virendra V. Singh1, Kevin Kaufmann1, Deniz A. Uygun1,2, Severina D. S. de Oliveira1 and
Joseph Wang1
1Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093, USA
2Department of Chemistry, Adnan Menderes University, Aydın, Turkey
*Presenter: muratuygun@gmail.com
1.Introduction
Carbon dioxide emissions are considered to be one of
the major contributions to climate change. Considerable
efforts aimed at mitigating the accumulations of CO2 are
currently underway. New approaches are thus being
developed to capture and sequester CO2, from effluents
and the atmosphere, including adsorption on oxides,
zeolites, metal–organic frameworks, and ionic liquids. Each of these CO2 capture processes has its own
disadvantages, such as high cost, high energy input, use
of harsh chemicals, and generation of pollutants.[1]
Storing the dissolved CO2 (as solid calcium carbonate)
is one of the most promising and environmentally
reliable methods to reduce the amount of CO2 dissolved
in water samples.[2]
Recent advances in the field of synthetic
nano/micromotors have expanded the performance,
capabilities, and functionalities of these tiny vehicles.
These developments have opened up a breadth of applications in diverse fields, ranging from energy
generation, environmental cleanup, or disease diagnosis
and treatment. For example, various detoxification
reactions and sensing protocols have been shown to be
rapidly accelerated by the autonomous motion of
catalytic micromotors and the enhanced fluid mixing
generated by such movement.[3,4]
Herein we describe a new approach based on carbonic
anhydrase (CA) functionalized micromotors for greatly
enhanced CO2 sequestration. This approach combines
the biocatalytic activity of CA with the self-propulsion of chemically powered micromotors through CO2-
saturated samples to act as highly efficient mobile
biocatalytic microscrubbers.
2.Methods
COOH-PPy:PEDOT/Pt tubular micromotors were
modified with the CA enzyme. The exposed surface
carboxyl groups were activated using 1-ethyl-3-(3-
dimethylaminopropyl)-carbodiimide / N-hydroxy
succinimide (EDC/NHS) for conjugation with CA.
The catalytic decomposition of the hydrogen peroxide
fuel at the inner Pt layer of the micromotor generates the
oxygen bubble thrust and leads to an efficient autonomous motion of the enzyme-modified
microengine. The micromotor-based rapid “on the-
move” biocatalytic hydration of CO2 to form a
bicarbonate ion, followed by the precipitation of CaCO3
in the presence of CaCl2 were described. The enzyme
CA is able to accelerate the inter conversion of CO2 to
bicarbonate, leading to significantly higher amounts of
CaCO3
3.Results
The CA modified micromotors undergo efficient
propulsion at high speeds (e.g., 106 µms-1 using 2%
peroxide), with curved, circular, and self-rotating
trajectories.
The mobile modified micromotors result in a high yield of CaCO3, corresponding to a 90% efficiency within 5
min (Fig 1.).
Figure 1 Micromotor-based CO2 sequestration and control
experiments. CO2 sequestration efficiency in the presence
of A) unmodified motor, B) modified motor with
denaturated CA, C) static CA-modified motors, D) the
static free CA; E) CA modified motors without sodium
cholate. F,G) CA-modified motors in pure water and in sea
water, respectively.
In conclusion, we have described a mobile CO2-
scrubbing platform that couples the biocatalytic activity
of CA with the autonomous movement of chemically
powered micromotors to offer highly efficient and rapid
CO2 sequestration. The self propelled CA-
functionalized micromotors are shown to accelerate the hydration of CO2 because of dramatically enhanced
fluid transport and continuous movement of CA. These
factors result in significant improvements in the CO2
sequestration efficiency and reaction time. The practical
utility of the new biomimetic micromotor approach has
been demonstrated in seawater.
4.References
[1] Ss G. Bhattacharjee, A. Kumar, T. Sakpal, R. Kumar, ACS
Sustainable Chem. Eng. 2015, 3, 1205.
[2] T. R. Karl, K. E. Trenberth, Science 2003, 302, 1719.
[3] V. V. Singh, F. Soto, K. Kaufmann, J. Wang, Angew. Chem. Int.
Ed. 2015, 54, 6896
[4] J. Wang, W. Gao, ACS Nano 2012, 6, 5745
Oral Presentation – OP0206
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Single-Particle Imaging for Biosensor Applications
M. Yorulmaz1*, O. Avcı2, E. Seymour1 and M. S. Ünlü2, 3
1 ASELSAN Research Center, Biotechnology Research Program Department, Ankara, 06370, Turkey
2 Department of Electrical and Computer Engineer, Boston University, Boston, Massachusetts 02215, USA
3 Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
*Presenter: myorulmaz@aselsan.com.tr
Abstract
Imaging of nanoparticles at the single particle level
is an important subject of recent research especially
for the applications in bio-imaging and
photovoltaics. Developing techniques in order to
image nanoparticles for early detection of diseases,
such as viral infections and cancer, as well as the use of nanoparticles for the treatment of certain types of
cancers has gained considerable attention.
ASELSAN Research Center has recently launched
research efforts in biotechnology and aims to
develop an in-vitro point-of-care biosensor that can
be used for diagnostic purposes. For this purpose, an
imaging technique that is sensitive, easy-to-
implement, low-cost, and easy-to-miniaturize is
essential. Such a technique will be useful to develop
biosensors which will transform into portable
medical imaging and detection devices, allowing for disease diagnostics in remote locations and
subsequent planning for clinical therapy.
Optical interferometric techniques have proven
utility in sensitive imaging of individual
nanoparticles in wide-field. We initially plan to
adopt the biosensor developed by Prof. Dr. Selim
Ünlü and his group. We will then study and
implement various optical schemes to improve the
sensitivity of this biosensor, targeting to detect
smaller biomolecules that would normally go
undetected with the current system.
We put efforts in creating practical, robust, and cost-effective solutions for non-laboratory environments.
Single-Particle Interference Reflectance Imaging
Sensor (SP-IRIS) has been successfully applied in
detecting synthetic nanoparticles and viruses [1]. In
spite of the strong imaging capability of the
technique, it does not require advanced optics parts.
Moreover, it can be developed using halogen light
sources instead of expensive lasers. It requires the
use of a silicon-silicon dioxide substrate as a
common-path interferometer. The schematic of the
optical setup is shown in Figure 1.
Figure 1 The schematics of SP-IRIS. (Adapted from Ref.
[2])
The interferometric detection of scattering signal
generated by the nanoparticle upon its excitation
with the light source is different than in the case of
detecting the direct scattered light, such as the
scattering signal in the dark field scattering
microscopy. The signal measured using the solely
scattering-based detection techniques scales as follows:
𝐼 ∝ |𝐸𝑠|2 (1)
where 𝐼 is the direct scattering signal and 𝐸𝑠 is
scattering field. As 𝐸𝑠 scales with 𝑟3, the direct
scattering signal scales with 𝑟6 and drops notably for nanoparticles with small sizes. For example, it
becomes very challenging to image gold
nanoparticles with sizes below 40 nm using direct
scattering signal.
On the other hand, the intensity measured using an
interferometric system is as follows:
𝐼 ∝ |𝐸𝑠 + 𝐸𝑟|2 ∝ 2|𝐸𝑠||𝐸𝑟|cos (ɵ𝑟𝑠) (2)
where 𝐸𝑟 is the reference field and the interference
signal that is the cross-term scales with 𝑟3. Therefore, interferometric methods allows for
imaging nanoparticles with smaller sizes. Using this
technique, it is possible to image dielectrics with
smaller scattering cross-sections than those of gold nanoparticles. The scattering image of 104 nm
polystyrene beads is shown in Figure 2.
Figure 2 The scattering signal of 104 nm polystyrene
beads.
Our goal is to enhance the sensitivity of this
technique through integration of polarization optics,
and achieve accurate sizing as well as shape and
orientation determination of nanoparticles in conjunction with the physical theory [3] based
forward model and various reconstruction models.
This enhancement will allow us to extend the use of
this technique for detecting a wide variety of
diseases including cancer using minute amounts of
sample.
References [1] Avci et al. Sensors, 15 (7), 17649-17665 (2015)
[2] Daaboul et al. Nano Letters, 10 (11), 4727-4731. (2010)
[3] Avci et al. Optics Express 24 (6), 6094-6114 (2016)
Oral Presentation – OP0207
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
miRNA Sensing Self-Propelled Hybrid Micromotors
Lutfi Oksuz1, Nilgün Dükar2*, Filiz Kuralay2, Gözde Yurdabak Karaca3, Umran Koc1, Emre Uygun1 and Aysegul
Uygun Oksuz3
1Department of Physics, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey
2Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey 1Department of Chemistry, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey
*Presenter: dukarnilgun@gmail.com
Abstract
Self-propelled micromotors have enabled exciting
applications in biomedical field such as delivering
drugs, nanoscale transport and assembly [1].
Particularly, chemically powered micro/nanomotors based on different chemical compositions and structures
that are capable of moving autonomously in the
presence of hydrogen peroxide fuel. Especially,
fabrication of nano and micro propellant systems
featuring specific cell recognitions in a short time frame
is highly anticipated. Ability of micromotors for
selective capture, and isolation of cancer cells based on
the selective binding and transport ability was
demonstrated [2,3]. miRNAs are gaining recognition as
critical regulators of many biological processes,
emerging as therapeutic targets for treating disease, especially cancer cells [4].
In this study, new tungsten oxide/poly(2-fluoroaniline)
(WO3/P2FANI) based hybride was used to obtain
WO3/P2FANI/Pt micromotors which propelled
catallytically using H2O2 fuel. Biosensing properties of
the micromotors were investigated for target miRNA
sequences. Fluorescence intensity and speed of
micromotors were analyzed using NİKON Eclipse Optic
LV100ND Microscopy.
Hybride structure was obtained by using rf rotating
plasma technique. Then, hybrid powders were dispersed
in the solvent and dropped onto cleaned glass. After
drying, hybride powders coated with platinum (Pt) by rf
Magnetron Sputtering method under 6 minutes and 25
Watt power. The effects of the surfactant and the fuel
concentration onto the speed of micromotors were
investigated.
Acknowledgments: This Project is supported by
TÜBİTAK (Project No: 1150098). F. Kuralay
acknowledges Turkish Academy of Sciences (TÜBA) as
an associate member and TÜBA-GEBİP programme.
References
[1] S.S. Banerjee, A. Jalota-Badhwar, K.R. Zope, K.J.
Todkar, R.R. Mascarenhas, G.P. Chate, G.V. Khutale, A.
Bharde, M. Calderon, J.J. Khandarea, Nanoscale 7 (2015) 8684.
[2] S. Balasubramanian, D. Kagan, C.J. Hu, S.
Campuzano, M.J. Lobo-Castañon, N. Lim, D.Y. Kang,
M. Zimmerman, L. Zhang, J. Wang, Angew. Chem. Int.
Ed. 50 (2011) 4161.
[3] D. Kagan, S. Campuzano, S. Balasubramanian, F.
Kuralay, G.-U. Flechsig, J. Wang, Nano Letters 11
(2011) 2083.
[4] J. Condea, E.R. Edelmana, N. Artzia, Advanced
Drug Delivery Reviews 81 (2015) 169.
Oral Presentation – OP0103
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Biosensing Strategy for Detection of Bacterial Susceptibility
Against Beta Lactamases
P. Kara1*, A. N. Yurtman2, H. Taslı2, M. Limoncu2 and M. Ozsoz3
1 Ege University, Faculty of Pharmacy, Analytical Chemistry Department, 35100, Bornova- Izmir, Turkey 2 Ege University, Faculty of Pharmacy, Pharmaceutical Microbiology Department, 35100, Bornova- Izmir,
Turkey 3 Gediz University, Faculty of Engineering, Nanotechnology Department , Turkey
*Presenter: pinar.kara@ege.edu.tr
Introduction
An antibiotic based electrochemical biosensor for direct
detection of beta lactamase susceptibility against
cefotaxim in E. coli cell was developed in this study.
Screen printed gold electrodes (AuSPE) were used as
sensor surface and Electrochemical impedance
spectrometry (EIS) was used as transducer. Cefotaxime antibiotic was immobilized onto AuSPE’s and antibiotic
modified AuSPE surfaces were incubated with bacteria
cell culture solution including whole bacteria. Clinical
E. coli isolates that excrete extended spectrum beta
lactamase (ESBL) which were sensitive and resistant to
cefotaxime have been used for the detection.
Staphylococcus aureus and pseudomonas auroginosa
isolates were used as negative controls. A non- beta
latam antibiotic vancomycine was also used for the
detection of biosensor selectivity. β-lactamase type
enzymes are produced by some bacteria, which are mainly responsible of catalyzing the hydrolysis of β-
lactam antibiotics that causes in bacteria resistance to
these antibiotics [1]. β-lactamases catalyze the
hydrolytic degradation of the amide bond in the four
membered β-lactam ring in β-lactam antibiotics, which
inactivates the β-lactam antibiotics. Extended-spectrum
β-lactamases (ESBLs), are often the cause for resistance
to newer cephalosporins and monobactams in the
members of the family of Enterobacteriaceae. ESBLs
have been widely found worldwide [2-4]. Several
methodologies for rapid and reliable detection of beta lactamase activity were studied including, enzyme-
linked immunosorbent assay [5], spectrophotometry [6],
chemiluminescence [7] and mass spectrometry [8]
techniques. The goal of our study is to develop a
biosensor for rapid, label free, high-throughput bacterial
antibiotic susceptibility determination.
Materials&Methods
Bacteria Culture: E. coli American Type Culture
Collection (ATCC) 25922 was used as the reference
strain. The broth microdilution test was performed by
using sterile, disposable, multiwell microdilution plates
(96 U-shaped wells), and Mueller–Hinton broth (BD, France) two fold serial dilutions were prepared in
microdilution plate.
Biosensor Preparation: The illustration of the study
procedure is shown in Figure 1.
Figure 1. Schematic presenstation of the study procedure.
Results and Discussion
Figure 2. EIS datas of cefotaxim coated AuSCPE; before c) and after
incubation with b) cefotaxim sensitive, a) cefotaxim resistant E. coli
bacteria.
Conclusion
An impidimetric cefotaxim cytosensor for direct
detection of beta lactamse activity and resistant in E.
coli strains was developed. The selectivity of biosensor
was evaluated by using non- beta latam antibiotic
vancomycine and Staphylococcus aureus and
pseudomonas auroginosa isolates. It was shown that the
designed biosensor is capable of label free; low-cost,
fast and reliable detection. Furthermore system can be
applied to produce susceptibility test kits.
References [1] Z. Xu, H.Y. Wang, S.X. Huang, Y. L. Wei, S.J. Yao, Y.L. Guo,
Anal. Chem., 82, (2010), 2113 -2118.
[2] P.A. Bradford, Clin. Microbiol. Rev., 14, (2001), 933-951.
[3] B.S. Kocazeybek, Chemother., 47, (2001), 396-408.
A.M.Hujer, K.S. A.M., Keslar, N.J. ,K.S. Dietenberger, C.R. ,N.J.
Bethel, A. Endimiani, R.A. Bonomo, Detection of SHV beta-
lactamases in Gram-negative bacilli using fluorescein-labeled
antibodies, BMCMicrobiol, 2009, 9, 46 -49.
[4] Z.Y.K. Naomi, Simple Photometric Assay of f-Lactamase Activity,
Antimicrobial Agents and Chemotherapy, 1972, 2, 356 -359
[5] P. Liang, R.I. Sanchez, M.T. Martin, Electrochemiluminescence
based detection of beta lactam antibiotics and beta lactamases, Anal.
Chem., 1996, 68, 2426 -2431.
[6] M.T. Cancilla, M.D. Leavell, J. Chow, J.A. Leary, Mass
spectrometry and immobilized enzymes for the screening of inhibitor
libraries, Proc.Natl.Acad.Sci. 2000, 97(22), 12008–12013.
[7] J.M. Park, J.I. Kim, H.W. Song, J.Y. Noh, M.J. Kang, J.C. Pyun,
Biosensors & Bioelectronics, 2015, 71, 306 -31
Oral Presentation – OP0307
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Functional GQDs nano-composite fabricated for direct and rapid detection of
BPA with paper based fluorescent system
Recep Üzek1,2*, Esma Sari1,2, Serap Şenel1, Arben Merkoçi2
1 Department of Chemistry, Hacettepe University, 2 Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and
Technology
*Presenter: ruzek@hacettepe.edu.tr
Abstract
In this study, we developed fluorescent sensor for the
sensitive and selective detection of BPA. NPs were
prepared by mini-emulsion polymerization and GQDs
were prepared by hydrothermal pyrolysis. GQDs were
attached to the NPs by EDC/NHS coupling. Fluorescent
nanosensor was characterized by using Zetasizer,
UV−vis and photoluminescence spectra, TEM and FTIR.
The nanosensor gave response to BPA as an
enhancement in the PL intensities. The detection limit
(LoD) and selectivity using the fluorescent nanosensor was found to be comparable to the other techniques. For
example, the LoD of SERS of core-shell Au
nanoparticles was demonstrated to be 0.53 µM and
competed with other methods such as
chemiluminescence, direct irradiation and UV-vis
methods which usually detect BPA with 0.1 nM LoD.
In summary, we have reported several significant novelty
as follows. First, the paper-based sensing system, hıgh
selectivity of MIP and fluorescence property of GQDs
were successfully combined to provide selective,
sensitive, rapid and inexpensive sensing strategy for BPA
monitoring. Besides, we have reported a sensing
platform than can be exploited with small volumes of
nano composite and BPA solution. In this respect, this
material could be easily produced for application in
fields of research and industrial because it is easy to
synthesize, cheap, non-toxic and environmentally friendly. In addition, sensing system can be easily
extended to the monitoring not only for pollutants but
also for bıomolecule by simply choosing different
functional monomer for the molecular imprinting
techniques.
Oral Presentation – OP0313
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Detection of Micro and Nanoparticles in a Microfluidic Device Using Resistive
Pulse Sensing Technique
S. Resul1*, E. Caglar2,3 and D. Memed4
1 Department of Mechanical Engineering, University of Siirt,
2 UNAM - National Nanotechnology Research Center, Bilkent University, Ankara, Turkey 3Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
4 Department of Bioengineering, University of Hacettepe
*Presenter: resulsaritas@gmail.com
1.Introduction
Resistive pulse sensing (RPS) technique, in 1996, has
been initially introduced for single-stranded RNA and
DNA molecules detection using a biological α-
hemolysin pore [1]. Then, the technique has been
employed for high-throughput detection of micro and
nanoparticles. Since, nanoparticles are used in many
application domains such as cosmetics, photovoltaics
and medicine [2]. On the other hand, dynamic light
scattering (DLS) method is commercially used to obtain
diameter and size distribution of the nanoparticles in suspension. However, accuracy of this technique is
relatively low compare to RPS technique [2] because,
while RPS detects and counts nanoparticles
individually, DLS measures scattered light with
fluctuations caused by Brownian Motion, which is not
observable if particle diameter is greater than 10 µm.
Here, we present the RPS technique to detect and count
micro particles individually as a consequence of
blocking ionic electrical current. We also synthesised
silica nanoparticles using tetraethylorthosilicate (TEOS)
method and counted them using DLS and compared the
results with those obtained from SEM.
2.Fabrication Method
Two photo-definable epoxy SU-8 thicknesses were
coated on silicon wafer and then patterned using
standard lithography. Obtained depth of the whole
microfluidic structure is 35 µm, and wide of
microconstriction (MR) is 20 µm. Polydimethylsiloxane
(PDMS) resin and curing agent are mixed well at ratio
of 10:1 and degassed for 1 hour and then poured to top
of fabricated mold. Microfluidic channel is bonded onto
a glass where gold readout electrodes are coated using e-beam evaporation. Figure 1 shows schematic image of
microfluidic channel and microconstriction image of
fabricated microfluidic device under microscope.
Figure 1 a) Schematic image of microfluidic channel
b) Microconstriction image of fabricated microfluidic
device under microscope (scale bar- 100 µm)
3.Results
Figure 2 demonstrates DLS measurement results of the
particles including size distribution and diameter of, and
presents a mean value. According to results, mean
diameter of the particles is found to be 468.9 nm.
However, when the diameter of the particles is
measured using SEM, it is found to be approximately
360 nm. Since DLS presents a mean value for particle
diameter. As it can be seen in Figure 3 while some of
the particles are agglutinated, others not.
Figure 2 DLS measurement results
Figure 3 SEM image of silica nanoparticles
4.Conclusion and Discussion
In this study, we show that DLS method is not always a
proper way to determine size distribution and diameter
of the particles when the results obtained from DLS are compared with those obtained from SEM or RPS
technique. RPS technique enables very reliable way for
particle detection since the technique measures the
particles individually.
5.References
[1] Kasianowicz, John J., et al. Proceedings of the National Academy
of Sciences (1996): 13770-13773.
[2] Fraikin, Jean-Luc., et al.."Nature nanotechnology 6.5 (2011): 308-
313.
Oral Presentation – OP0211
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Synthesis of Functionalized Fluorescent Carbon Nanoparticles as Artificial
Enzymes and Signaling Tools for Their Use in Bioanalysis
G. Rükan1,2, *, A.Ö. Melis1, B. Burcu1 and B. Dilek2,3
1 Functional Nanomaterials Lab, Chemical Engineering Dept., Mersin University,
Çiftlikköy Kampüsü 33343, Mersin, Turkey 2 Mersin University Advanced Technology Education, Research and Application Center (MEITAM),
Mersin University, 3Mersin University Faculty of Pharmacy Department Of Pharmaceutical Toxicology
*Presenter: rgenc@gmail.com
1.Introduction
Fluorescent nanoparticle-based biolabels are promising
tools which could give pave the way to develop new
medical diagnostic tools based on their advanced optical
properties with extreme resistance to photobleaching
compared to conventional molecular probes. Although,
significant progress has been made in nanoparticle-
based biological labelling and imaging, the concern
about the possible toxicity of these materials at
functional concentrations has severely limited their
widespread use in clinic [1,2]. Carbon dots are new member of carbon based
nanostructures. They can be synthesized from several
carbon sources and at nanosize show auto-fluorescence.
This materials with low photo-bleaching, low
cytotoxicity, biocompatibility are of great interest due to
their potential in many fields requiring non hazardous
materials.(4) Here, we report fluorescent carbon
nanoparticle-based nanolabels which could be suitable
for bio-imaging, diagnostics as fluorescent nanolabel as
well as due to surface functional moeities, they function
as enyzme mimitics for oxidation reactions. To do so,
we used different carbon sources including molasses and some industrial co-products as carbon source and
mixed them with different pigments, metals and so on to
obtain various carbon nanodots with so many different
properties. Synthesized fluorescent carbon nanoparticles
were further conducted to bioassays for the analysis of
several medically important molecules such as
Hydrogen Peroxide, Dopamine and Mercury.
2.Materials and Methods
Synthesis of FCNPs The synthesis of FCNPs was accomplished according to
the method described previously by Mukherjee [3]. A
homogeneous suspension of carbon source was obtained
without aggregation by vigorous mixing.. The mixture
was maintained at 250°C for 45 minutes until a dark,
caramelized, semi-solid texture was obtained. The
resulting material was dissolved in 2 mL of MilliQ-
water (Millipore Inc., Ω = 18 MΩ·cm). The suspension
was centrifuged at 5.000 rpm for 30 minutes; the final product was vacuum-dried. The synthesis of the carbon
nanoparticles were monitored by irradiating with a 365
nm UV light source. Further characterizations of the
synthesized CNPs were performed as described above.
Characterization of fluorescent CNPs
Ultraviolet-visible (UV-Vis) spectra of CNPs were
recorded using an Shimadzu UV-1800 UV-VIS
spectrophotometer ). X-ray diffraction (XRD) analyses
were performed in a Rigaku Smartlab Intelligent X-ray
diffractometer (XRD). Fourier transform infrared
(FTIR) spectroscopy was performed in a range of 400–
4.000 cm−1. Transmission electron microscopy (TEM;
JEOL) was used to determine the size and morphology
of the dispersed FCNPs. Fluorescence spectra of particle
solutions were measured using a Varian Cary Eclipse Fluorescence Spectrophotometer.
Figure 1. True colour photographs of fluorescence
emission from synthesized carbon nanodots (Ext./400nm). Core image has been taken from Ref [4].
Analysis Presence of dopamine and Mercury from liquid
ssamples was measured by evaluating the changes in the
fluorescence response of different carbon nanoparticles
while H2O2 analysis was carried out by measuring the
color change of ABTS following a standard peroxides
test.
Acknowledgements. This study is partially funded by
Mersin University Scientific Research Project Unit
(Project No: 2016-AP4-1791)
3.References
(1) Liu, Q.; Chen, M.; Sun, Y.; Chen, G.; Yang, T.; Gao, Y.; Zhang,
X.; Li, F.. Biomaterials 2011, 32 (32), 8243–8253.
(2) Schütz, M.; Steinigeweg, D.; Salehi, M.; Kömpe, K.; Schlücker,
S. Chem. Commun. 2011, 47 (14), 4216–4218.
(3) Mukherjee, P.; Misra, S. K.; Gryka, M. C.; Chang, H.-H.; Tiwari,
S.; Wilson, W. L.; Scott, J. W.; Bhargava, R.; Pan, D. Small 2015,
11 (36), 4691–4703.
(4) Demchenko, A. P.; Dekaliuk, M. O. Appl. Fluoresc. 2013, 1 (4),
042001.
Oral Presentation – OP0106
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation of Polypyrrole based electrodes for Glucose 6-phosphate
determination
S. Sahin1*, I. Ozmen1, G. Yıldırım2 and S. Percin Ozkorucuklu2
1 Department of Chemistry, Suleyman Demirel University,
2 Department of Molecular Biology and Genetics, Istanbul University,
*Presenter: selmihansahin@sdu.edu.tr
Introduction
The determination of the glucose 6-phosphate (G6P) in
blood or human tissue informs about many diseases
associated with glucose 6-phosphate dehydrogenase
(G6PD) deficiency [1]. Therefore, there are several
studies on improving of biosensor for glucose-6-
phosphate measurement. To date, developed biosensors
have based on combinations of G6PD and different mediators or enzymes [2].
The aim of this study was to prepare G6P biosensors
which contain polypyrrole (PPy) and Fe3O4-Chitosan
(CS) nanoparticles and optimize several parameters for
maximum response.
Methods
Ppy and Fe3O4-CS-PPy electrodes were prepared
electrochemically onto pencil graphite electrode.
Electrochemical synthesis was performed with pyrrole
in acidic solution at constant current density of 0.35 mA
cm-2. Surface morphology of electrodes was determined with SEM analysis. Then, glucose 6-phosphate
dehydrogenase (G6PD) was immobilized on electrodes
via glutaraldehyde. Optimum enzyme immobilization
conditions were determined for two electrodes.
Chronopotentiometric curves of electrodes were
recorded at current density of 0.25 mA cm-2 for different
G6P concentrations. Various optimization studies, such
as pH, enzyme concentration, and NADP+
concentration, were performed to obtain maximum
responses for G6P measurement. To determine the
usefulness of the prepared G6P biosensor, human blood serum samples were spiked with known concentrations
of G6P and were used as analytes for the measurements.
Results
As a result, Ppy and Fe3O4-CS-PPy electrode showed a
broad lineer response to G6P in the range of 0,025 to
0.25 mM and 0.005 to 0.1 mM, respectively. The results
of optimization studies are given in Table 1. Surface
morphology of Fe3O4-CS-Ppy and PPy electrode is
shown in Figure 1.
Table 1 Optimization results
Paramet
ers PPy
Fe3O4-CS-
PPy
pH 8.5 8
Enzyme
concentration 2 U 1 U
NADP+ 1.25 mM 1.25 mM
concentration
Figure 1 SEM images of naked pencil graphite
electrode (a) and electrochemically prepared PPy (b)
and Fe3O4-CS-PPy (c) electrodes onto pencil graphite
References
[1] S. Banerjee, P. Sarkar, A. P. F. Turner,
Amperometric biosensor based on Prussian Blue
nanoparticle-modified screen-printed electrode for
estimation of glucose-6-phosphate. Anal. Biochem.
439(2013) 194–200. [2] Y. Cui, J. P. Barford, R. Renneberg, Development
of a glucose-6-phosphate biosensor based on
coimmobilized p-hydroxybenzoate hydroxylase and
glucose-6-phosphate dehydrogenase. Biosens.
Bioelectron, 22(2007) 2754–2758.
Oral Presentation – OP0107
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Detection of Alzheimer`s Protein on Polycarbonate Nanopillared Films by Using
Surface Enhanced Raman Spectroscopy
Sevde Altuntas1*, Can Simon Pervane2 and Fatih Buyukserin3
1Biomedical Engineering Graduate Program, TOBB Univ. of Econ. & Technology, Ankara 06560, Turkey
2Institute of Complex Systems Simulation, University of Southampton, Southampton SO171BJ, United Kingdom 3Department of Biomedical Engineering, TOBB Univ. of Econ.& Technology, Ankara 06560, Turkey
*Presenter: sevde.altuntas@etu.edu.tr
Introduction Alzheimer`s disease is responsible for neuronal damage
of cerebral cortex and hippocampus because of Amyloid
β 1-42 protein accumulation. The protein detection
studies have gathered around ELISA assay and PCR
assays which are expensive, require specialized
personnel and can contain complex protocols. On the
other hand, Surface-enhanced Raman Spectroscopy (SERS) can potentially allow even single molecule
detection in solutions or solid surfaces. In addition,
SERS signal from a target molecule can be further
increased by using nanopatterned surfaces when
compared to smooth counterparts. Moreover, Raman
signals are specific to molecules, so one can comment
about content of a sample. For this reason we focused
Alzheimer protein detection on nanopatterned polymer
surface by using SERS techniques.
Materials&Methods
Nanoporous anodic aluminum oxide membrane (AAM) was synthesized by using two step anodization method
from high purity aluminum. According to electrolyte
type, anodization time, voltage values and temperature,
AAM thickness, column structure or pore size were
arranged. The nanoporous film was coated with n-
octadecyltrichlorosilane to decrease its surface energy.
AAM was coated polycarbonate (PC) solution (wt/v
6%) by using drop-casting method. After solvent
evaporation, the PC film was removed from the surface.
The nanopatterned surface was coated with gold
(thickness: 10, 20 and 30 nm) by using thermal
evaporator (Nanovak, NVTS 400). After gold coating process, the polymer films were decorated with different
concentrations of Thioflavin – T which is widely used
to visualize and quantify the presence of misfolded
protein aggregates called amyloid. SERS technique was
used for protein and Thioflavin – T detection (DeltaNu
Examiner Raman microscope. Laramie, WY).
According to decrease of Thioflavin – T signal, amount
of the amyloid protein were determined. Limit of
detection was found 0.5 pg/ ml for the protein.
Results
In this context, our study proposes to fabricate diagnostic test models that utilize Au-coated
nanopatterned PC surfaces modified with Thioflavin - T
to detect low concentrations of Amyloid-β 1-42 protein
in water and artificial saliva medium by the
enhancement of protein SERS signal. Nano patterned
PC surface was fabricated by using nanoporous AAM as
a mold. To AAM column structure, three different types of PC arrays were fabricated to enhance SERS signals.
The PC films were then decorated with Au and
Thioflavin – T for detection Amyloid-β 1-42 protein.
(Figure 1). The protein detection studies were conducted
in water and artificial human saliva. SEM, SERS, FTIR,
fluorescence microscopy and contact angle
measurements were carried out for the characterization
of different surfaces and further demonstration of the
protein attachment. In addition to experimental study,
computational enhancement studies were carried out by
using COMSOL Multiphysics.
The results will be presented comparatively.
Figure 1 SEM images of nanopatterned surface (a), and branched nanopatterned surface (b). SERS spectrum of Thioflavin – T modified nanopatterned and flat PC surface (c).
Conclusion To conclude, SERS intensity of multibranched
nanopatterned surface is much higher than other
samples because of the high hot spot probability.
Besides SERS results of 20 nm gold coating and 10-5 M
Thioflavin – T decoration are more favorable to
measure amyloid amount. In addition to all of them, the
COMSOL results will be shared during presentation.
Acknowledgment: This work was supported by The
Scientific and Technological Research Council of
Turkey (TUBITAK) Grant No: 214Z167.
Oral Presentation – OP0209
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Smart Surface Based Guiding of Microdroplets Over Laser Ablated
Sinusoidal Rail
Z. Rashida, Y. Morova
b, B. Yalızay
b, U. C. Çoşkun
c, A. Erten
a, A. Jonas
b and A. Kiraz
a,d*
a Koç University, Department of Physics, Sariyer, Istanbul b Istanbul Technical University, Department of Physics, Maslak, Istanbul
c Istanbul Technical University, Department of Mechanical Engineering, Maslak, Istanbul d Koç University, Department of Electrical and Electronics Engineering, Sariyer, Istanbul
*Presenter: akiraz@ku.edu.tr
Abstract
Droplet-based microfluidic systems have been shown to
be compatible with many chemical and biological
reagents and capable of performing a variety of ‘‘digital
fluidic’’ operations that can be rendered, programmed
and reconfigured. This platform has dimensional scaling
benefits that have enabled controlled and rapid mixing
of fluids in the droplet reactors, resulting in decreased reaction times. This, coupled with the precise generation
and repeatability of droplet operations, has made the
droplet-based microfluidic system a potential high
throughput platform for biomedical research and
applications.
We present a method of water droplet generation using
oil as a host liquid using T-junction geometry and
guiding of those droplets on hydrophilic glass slide rail
surrounded by hydrophobic PDMS surface. The
trajectory of different sizes of the droplets is determined
using cross correlation algorithms for different depths of
the track over the coated cover glass slide. The
coordinates of the track, on the other hand, are evaluated by scanning the whole image along the two
dimensions and detecting the color transition while
moving from left to right along the rail. The distance
between the centers of droplet path and track is
calculated for several droplets and presented in the form
of histograms to find the quality of guiding for three
different specimen.
Oral Presentation – OP0312
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Dielectrophoretic Spectra of Polymorphonuclear White Blood Cells
Z. Çağlayan1*, Y. Demircan Yalçın1, 3, G. Özkayar2, 3, E. Özgür3 and H. Külah1, 3, 4
1 Department of Electrical and Electronics Engineering, Middle East Technical University, Ankara, Turkey
2 Department of Biomedical Engineering, Middle East Technical University, Ankara, Turkey 3 Mikro Biyosistemler Inc.
4 METU-MEMS Research and Application Center
*Presenter: zcaglayan@mems.metu.edu.tr
1.Introduction
Dielectrophoresis (DEP), is a sensitive and rapid
method, utilized for separation of dielectrically different
cells, even with similar sizes in a label-free manner. For
cell separation through DEP, dielectric properties of the cells should be known. In this study, dielectrophoretic
spectra of polymorphonuclear white blood cells (WBCs)
were investigated.
2.Theory and Design
Dielectrophoresis is described as the relative movement
of particles and suspending medium in nonuniform
electric field. Time averaged DEP force for spherical
particles is:
𝐹𝐷𝐸𝑃 = 2𝜋𝜀𝑚𝑟3𝑅𝑒(𝑓𝐶𝑀)𝛻|𝐸2| (1)
where r is the radius of the cell, 𝛻|𝐸2| is the gradient of
the external electric field magnitude square, 𝜀𝑚 is the
permittivity of the medium and 𝑅𝑒(𝑓𝐶𝑀) is the real part
of the Clausius-Mossotti factor. According to 𝑓𝐶𝑀,
particles can be either pulled towards stronger electric
field region (positive DEP-pDEP) or pushed towards
weaker electric field region (negative DEP-nDEP) [1].
A DEP spectrum device, with reciprocal V-shaped
planar-electrodes was utilized to obtain DEP spectra of
polymorphonuclear WBCs by using pDEP effect. The
gap between electrode tips is 20μm. The angle between
arms of electrodes is 30˚. A parylene chamber
(h=20μm) was constructed to create reservoir for cell
solution. The schematic and the fabricated views of this
device can be seen from Figure 1.
Figure 1 Schematic view (a) and the fabricated
view (b) of DEP spectrum device
3.Results and Discussion
For each test, 4µl cell suspension was put into the
reservoir and waited until solution motion stopped. 10Vpp at 15 different frequencies (100 kHz-50 MHz)
was applied and the motion of cells was recorded
with a CCD camera (SONY/DXC-107AP). Velocity
of cells was determined through Meazure and
VirtualDub. When velocity of the solution is zero,
velocity of cells can be directly related to
Re(𝑓𝐶𝑀) 𝛻|𝐸2|, keeping 𝛻|𝐸2| as same for each cell. WBCs can be examined in two main groups as
polymorphonuclear WBCs (neutrophils and
eosinophils) and mononuclear WBCs (lymphocytes,
monocytes and basophils). The first three most
abundant WBC types are neutrophils, lymphocytes
and monocytes in the order, forming the largest
portion of total WBCs in blood [2]. Therefore, to get
knowledge about DEP spectra of WBCs, it is
decided to start with polymorphonuclear WBCs.
For tests, whole blood is taken from healthy woman
donors. After treating the blood with Ficoll,
developed OptiPrep procedure is applied to get polymorphonuclear and mononuclear WBCs
separately. The procedure is based on the formation
of density gradient. The obtained velocity vs.
frequency profiles for two donors with standard
deviations can be seen from Figure 2.
Figure 2 Velocity vs frequency profile of
polymorhonuclear WBCs of two healthy donors
As a future work, remaining dielectrophoretic
spectra of mononuclear WBCs, will be examined
and compared with polymorphonuclear WBCs. With
this way, DEP spectra of WBCs will be obtained.
4.References
[1] Y. Demircan, A. Koyuncuoğlu, M. Erdem, E. Özgür, U. Gündüz,
and H. Külah. “Detection of Imatinib and Doxorubicin
Resistance in K562 Leukemia Cells by 3D-Electrode
Contactless Dielectrophoresis,” Transducers, 2013, pp. 2086-
2089
[2] White Blood Cell Count (WBC) and Differential.” Internet:
http://www.rnceus.com/cbc/cbcwbc.html, 2013 [10.11.2015].
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donor 1 donor 2
Oral Presentation – OP0105
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Point-of-Care Measurement of Erythrocyte Sedimentation Rate
Z. Işıksaçan1* and Çağlar Elbüken1
1 Institute of Materials Science and Nanotechnology, National Nanotechnology Research Center, Bilkent
University, Ankara, Turkey
*Presenter: ziya.isiksacan@gmail.com
Introduction
Erythrocyte aggregation (EA) is a process where erythrocytes form face-to-face structures at stasis or low
shear rates. Erythrocyte sedimentation rate (ESR) is a 1-
hour clinical test for inflammation screening [1]. Here,
we report a point-of-care device that measures ESR
from EA using 40 µl fingerstick blood in 1.5 minutes
with a novel measurement method.
Methods
The measurement system consists of a disposable
cartridge and a portable opto-electro-mechanical
analyzer. The cartridge channel is illuminated with an
infrared light. A constant pressure is applied to the
channel for complete disaggregation. As the
erythrocytes aggregate, the transmitted light intensity
from the erythrocytes in the channel is recorded for 1.5
min. The intensity level is lowest at complete
disaggregation and highest at complete aggregation.
From this data, ESR is measured.
Results and Discussion
For experimental verification of the measurement
method, first, we added dextran polyglucose, an
aggregation inducer, of different concentrations in blood
samples obtained from a healthy male volunteer. We
measured the ESR of the samples using our system and
the conventional 1-hour test. We showed that the
amplitude of the transmitted signal is in correlation with
the conventional test result with R2 of 0.98 using linear
regression.
Secondly, we used blood samples from three patients.
The ESR values were measured using our system and the standard Westergren method. We showed that the
correlation between the two methods is very good with
R2 of 0.99 using linear regression.
Conclusion
This work demonstrates that our point-of-care reliably
measures ESR from EA. To the best of our knowledge,
this is the most rapid ESR measurement method
provided in the literature. The measurement takes only
1.5 minutes (in comparison to 1 hour in the
conventional test) and uses only 40 µl whole blood (as
opposed to 2 ml blood used in the conventional test).
When a high speed camera is integrated onto the cartridge, we can also monitor EA process to better
understand the mechanism of this physiological
phenomenon.
Figure 1: Standard ESR versus microfluidic ESR test
results using different dextran concentrations
Figure 2: Standard ESR versus microfluidic ESR test
results using blood samples from different patients
Acknowledgement
The authors acknowledge support from The Scientific
and Technological Research Council of Turkey
(TUBITAK project no. 213S127).
References
[1] “Red Blood Cell Aggregation,” O. Baskurt, B. Neu,
H.J. Meiselman, CRC Press (2011).
Oral Presentation – OP0204
Poster
Presentations
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Highly monodispersed droplet generation using a microfluidic system
Ali Kalantarifard1,2* and Çaglar Elbuken1,2
1 UNAM - National Nanotechnology Research Center, Bilkent University, Ankara, Turkey
2 Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, Turkey
*Presenter: a.kalantarifard@bilkent.edu.tr
1. Introduction
During the last decade droplet generation has become a
significant field of research because of its wide
applications in science and microscale engineering. The
ability to generate highly monodispersed microdroplets
has applications in various fields such as chemical,
biological and medical study [1]. One of the needs to
achieve monodisperse droplets is having stable and
uniform flow rate of the fluids which are supplied by
the pumps [2]. There are mainly two types of pumps
used for making droplets: pressure-driven pump and
syringe pump (Figure 1). By using pressure-driven
pump, two immiscible fluids can be supplied to the inlets of the chip by pressurized air. For syringe pump,
fluids are supplied to microchannel by pushing the
plunger by the gear motor [3]. In this study, the
performance of these two pumps is compared for
generating monodisperse droplets. The same number
and size of droplets are investigated numerically and
experimentally to compare the results in terms of
monodispersity.
Figure 1 Schematic of syringe pump and pressure
pump systems
2. Experimental Setup
Experimentally droplet generation is performed by
using syringe pump and pressure pump. For both
experiments, the two immiscible fluids are silicone oil
(carrier fluid) and deionized water (dispersed phase).
The PDMS microchannel is fabricated using soft
lithography and then bonded on the glass slide.
Numerical Simulation
The same geometry as the fabricated device was
simulated numerically. In order to find the flow field and solving the equations Comsol 5 with laminar two-
phase flow level-set method was used. In addition, flow
rate and pressure were controlled as initial condition to
attain the same size of droplet obtained in the
experiments. Then, monodispersity of the droplets was
analysed by calculating area of each droplet and
comparing with experimental results [4].
3. Results and Discussion
Figures 2 and 3 show the results of droplet area
distribution in numerical and experimental model
respectively. Moreover, as it is shown in Table 1,
coefficient of variation of droplets area for syringe
pump case is higher than the pressure pump case in both
models.
Figure 2 Droplet area in numerical model
Figure 3 Droplet area in experimental model
Table 1 Coefficient of Variation of droplet area
Experimental Numerical
Pump Syringe
pump
Pressure
pump
Syringe
pump
Pressure
pump
CV% 1.5 3.87 0.63 1.28
4. Conclusion
The numerical and experimental results show that by
using syringe pump we can obtain more monodispersed
droplets. Also, according to results in both cases, CV
for experimental method is higher than numerical, due
to the fluctuation of flow rate and pressure induced at
the experimental setup.
References
[1] Teh S, Lin R, Hung L, Lee A P, 2008 Lab Chip 8 198. [2] Zeng W, Jacobi I, Li S, Stone H, 2015 Journal of Micromechanics and
Microengineering 25 115015.
[3] Korczyk P M, Cybulski O, Makulskaa S and Garstecki P 2011 Lab Chip 11 173.
[4] Basu A S 2013 Lab Chip 13 1892.
0
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1,6
9E+
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1,7
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05
1,7
4E+
05
1,7
5E+
05
1,7
6E+
05
Co
un
t
Droplet area (µm2)
Syringe Pump-Numerical model
05
101520
1,6
2E+
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1,6
3E+
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1,6
5E+
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1,6
6E+
05
1,6
7E+
05
1,6
8E+
05
1,6
9E+
05
Co
un
t
Droplet area (µm2)
Pressure Pump- Numerical model
05
101520
1,6
1E+
05
1,6
3E+
05
1,6
4E+
05
1,6
6E+
05
1,6
7E+
05
1,6
9E+
05
1,7
0E+
05
1,7
2E+
05
Co
un
t
Droplet area (µm2)
Syringe Pump- Experimental model
010203040
1,6
0E+
05
1,6
4E+
05
1,6
8E+
05
1,7
2E+
05
1,7
6E+
05
1,8
0E+
05
1,8
4E+
05
1,8
8E+
05
Co
un
t
Droplet area (µm2)
Pressure Pump- Experimental model
Poster Presentation – PP0101
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Graphene/Pt nanoparticles/nafion nanocomposite as a novel electrochemical
sensor for voltammetric determination of aliskiren
A.K. Ates1*, E. Er
1 and N. Erk
1
1 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara-Turkey
*Presenter: akates@ankara.edu.tr
1. Introduction
The renin-angiotensin-aldosterone system (RAAS) has
long been recognized to play a significant role in
hypertension pathophysiology. Certain agents that
modify the RAAS can control blood pressure and
improve cardiovascular outcomes. Aliskiren (ALS) is
the first of a new class of antihypertensive agents
known as renin inhibitors. Renin inhibitors are antihypertensive drugs that block the first step in the
renin-angiotensin system. Their mechanism of action
differs from that of the angiotensin-converting enzyme
inhibitors and angiotensin-receptor antagonists, but like
these drugs, renin inhibitors interrupt the negative
feedback effects of angiotensin II on renin secretion [1-
2]. The determination of ALS at low-level has a great
importance especially in real samples. Herein, we
presented a facile and effective electrochemical
nanosensor based on graphene/platinum
nanoparticles/nafion (GRP/PtNPs/NFN) for the electrochemical sensing of ALS using adsorptive
stripping differential pulse voltammetry (AdsDPV).
2. Experimental
Graphene/platinum nanoparticles (GRP/PtNPs)
nanocomposite was produced from graphene oxide
(GO) via one-step chemical reduction method [3-4]. For
the fabrication of proposed sensor, GRP/PtNPs solution containing NFN (0.25%, v/v) was prepared to constitute
the GRP/PtNPs/NFN nanocomposite. A certain amount
of dispersed GRP/PtNPs/NFN solution was dropped
onto a clean GCE surface to obtain the proposed
modified electrode (GRE/PtNPs/NFN/GCE).
The electrochemical performance of ALS on
GRP/PtNPs/NFN/GCE was investigated in detail by cyclic voltammetry (CV) and AdsDPV. An irreversible
and well-defined oxidation peak approximately at 1100
mV was observed on GRP/PtNPs/NFN/GCE using
AdsDPV. Under optimal conditions,
GRP/PtNPs/NFN/GCE exhibits good sensitivity and
selectivity in the detection of ALS. The linear
concentration range for ALS was found to be 0.1-5.0
µM with a low detection limit.
3. Conclusion
It is the first time that a novel and highly sensitive
graphene-based electrochemical platform was
designed for the sensing of ALS. For this purpose,
GRP/PtNPs/NFN nanocomposite has been
fabricated as an electrochemical sensing
material. GRP/PtNPs/NFN/GCE sensor exhibited
an outstanding analytical performance towards the
ALS due to its unique physical and chemical
properties of graphene and platinum nanoparticles.
The developed method was successfully applied to the determination of ALS in human plasma with
satisfactory recovery results. It is concluded that
GRP/PtNPs/NFN/GCE could be promising
alternative sensor for routine analysis of ALS in
real samples.
References
P. Wal, A. Wal, A. Kai. R, A. Dixit, J Pharm
Bioallied Sci. 2011 Apr-Jun; 3(2): 189–193.
J.W. Cheng, Clinical Therapeutics, 2008
Jan;30(1):31-47.
W.S. Hummers, R.E. Offeman, J. Am. Chem. Soc. 80 (1958) 1339.
T.Q. Xu, Q.L. Zhang, J.N. Zheng, et al.,
Electrochim. Acta 115(2014) 109–115.
Poster Presentation – PP0102
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Graphene based hydrogen peroxide sensitive biosensor for glucose sensing
A.Öncül1*, S.Cete2 and A.Yasar2
1Institue of Natural Sciences, Gazi University, Ankara, Turkey 2 Department of Chemistry, Gazi University, Ankara, Turkey
*Presenter: asenaoncul@gmail.com
1. Introduction
Graphene is a carbon allotrope formed with sp2
hybridized carbon atoms arranged in a 2-dimensional
structure. [1] Its physical properties, such as excellent
carrier mobility (200.000 cm2V-1s-1 for single layer) [2] and very large surface area (2630 m2g-1) [3] make it a
very popular choice for various applications.
Biosensors including glucose biosensors are becoming
increasingly important due to their applications in
biological and chemical analyses, clinical detection, and
environmental monitoring. We design a sensitive
electrochemical sensor for glucose based on a glassy
carbon electrode that was modified with a
nanocomposite containing graphene, platinum
nanoparticles (Pt-NPs) and nafion. The significance of
glucose in human metabolism is well known, as is the fact that the defects in glucose level lead to
complications of diabetes. [4]
2. Materials and Methods
High-quality graphene (GR) was produced by an
effective chemical method using Hummers' method. [5]
GR/NFN(Nafion) preparation, the NFN solution was
added to obtain 0.25 (m/v) nafion concentration in the
GR solution. The quantification of glucose can be
achieved via electrochemical detection of the
enzymatically unchained H2O2. The immobilization of
glucose oxidase (GOD) over Nafion-solubilized metal
nanoparticles dispersed graphene and electrode has been
achieved by cross-linking with glutaraldehyde. The performances of the biosensor have been investigated
by electrochemical method at an optimum potential of
+0.6V in pH 7.0 phosphate buffer. All the
electrochemical measurements were performed with a
conventional three-electrode system.
3. Conclusions
There are many reports regarding the electro catalytic
activity of gold and platinum for the sensing
applications of glucose. [6]
In our study glucose biosensor based on immobilization
of GOD in Pt nanoparticles/graphene/NFN
nanocomposite film is responsive to a low concentration
of H2O2 (~5µM) and two different linear determination
ranges of 10-5-10-4 M (shown in figure-1) and 10-3-10-1
M are detected.
According to literature values [7-10] our sensor has low
detection limit and long linear range among to other
studies. This properties shows us our sensor is good
candidates for biochemical applications.
Figure 1 Concentration vs. Current between
10-5-10-4 M H2O2 +0.6V in pH 7.0 phosphate buffer
4. References
[1] A. K. Geim and K. S. Novoselov, Nat. Mater., 2007, 6, 183–191. [2] K. I. Bolotin, K. J. Sikes, Z. Jiang, M. Klima, G. Fudenberg,J. Hone, et al., Solid State Commun., 2008, 146, 351–355. [3] Y. Zhu, S. Murali, W. Cai, X. Li, J. W. Suk, J. R. Potts and R. S. Ruoff, Adv. Mater., 2010, 22, 3906–3924. [4] Shankaran DR, Uehara N, Kato T. 2008. Biosensors and
Bioelectronics 18:721–728. [5] W.S.Hummers, R.E.Offeman, J.am.Chem.Soc.80 (1958) 1339 [6] R.B. Rakhi, K. Sethupathi, S. Ramaprabhu, J. Phys. Chem. B 113 (2009) 3190–3194. [7] R. Ning, W.B. Lua, Y.W. Zhang, X.Y. Qin, Y.L. Luo, J.M. Hu, A.M. Asiri, A.O. Al-Youbi, X.P. Sun Electrochimica Acta, 60 (2012)
[8] E. Jin, X.F. Lu, L.L. Cui, D.M. Chao, C. Wang Electrochimica Acta, 55 (2010), p. 7230 [9] X.X. Liu, H. Zhu, X.R. Yang Talanta, 87 (2011), p. 243 [10] S. Woo, Y.R. Kim, T.D. Chung, Y. Piao, H. Kim Electrochimica Acta, 59 (2012), p. 509
Poster Presentation – PP0103
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Enantioselective Chiral N-doped Graphene Quantum Dots
Aslı İ. Doğan1*, Funda Çopur1, Erhan Zor2, Sabri Alpaydin3 and Haluk Bingol3
1 Institute of Science, Necmettin Erbakan University, Konya/Turkey
2 Department of Science Education, Necmettin Erbakan University, Konya/Turkey 3 Department of Chemistry Education, Necmettin Erbakan University, Konya/Turkey
*Presenter: asliiremdogan@gmail.com
Abstract
Although the enantiomers of chiral molecules taking a
fundamental place in chemistry, biochemistry and
pharmacology have identical chemical and physical properties, they may exhibit different reaction ability in
stereochemical reactions [1]. Within this context,
enantiomeric recognition of chiral molecules by
different chiral selector is becoming one of the most
important fields in analytical chemistry especially for
pharmaceutical industry, clinical analysis, food analysis
and forensic analysis. The commercial analytical
techniques for recognizing enantiomers are usually
based on high performance liquid chromatography and
capillary electro-chromatography. Due to the
advantages such as the low-cost, detection limits etc., a number of studies and reviews have been published
related to spectrofluorometric method which is one of
the most preferred methods. In these studies, small
organic molecules, macrocyclic compounds, metal
complexes, polymers and nanomaterials have been used
as sensors in the stereochemical reactions. With the
advances in nanotechnology over the past two decades,
nanomaterials have been used almost in all areas and an
increasing attention is focused on chiral detection
studies. Among them, graphene quantum dots (GQDs)
are emerging as promising fluorescent materials for
biological applications, owing to their unique properties, such as excellent biocompatibility and
solubility in physiological conditions [3].
Herein, a novel route to prepare different types of light-
emitting chiral nitrogen-doped GQDs (cN-GQDs) is
demonstrated by a hydrothermal process between GQDs
and D-/L-PA as chiral precursors. The purified cN-
GQDs with silica column showed different emission
properties based on their stereochemical moiety. cN-
GQDs were synthesized in three steps. As the first step,
graphene oxide (GO) was prepared by following the
improved Hummers method. In the second step regarding the conversion of GO to nitrogen-doped
GQDs (N-GQDs), the further cutting and in situ doping
progress of GO was performed in DMF media using a
Teflon-lined autoclave at 200 °C for 4 h [4]. After
cooling, filtering and centrifuging, in the last step, N-
GQDs were converted to cN-GQDs by applying the
second hydrothermal process at 180 °C for 24 h
between GQDs and D-/L-PA [5]. The freshly as-
prepared cN-GQDs have been purified via silica column
chromatography (Fig. 2). The obtained cN-GQDs were
characterized by FT-IR, Raman, XPS and TEM. From
the purified products via silica column chromatography,
N-GQDs conjugated with L-PA (L-PA@N-GQDs)
shows a green photoluminescent (PL) at 505 nm, on the
contrary, D-PA@N-GQDs shows very week PL around
470 nm as can be seen in Figure 1. The corresponding PL spectra showing excitation and emission changes for
both materials are also given in Figure 1.
Figure 1 Column chromatography for purification,
photographs under daylight and UV light, and
excitation and emission spectra of cN-GQDs.
We also explored the feasibility of fluorescent L-
PA@N-GQDs for the selective chiral recognition of
chiral amino acids. Among them, the different quenching behaviors were observed when cysteine
enantiomers were added into the aqueous solution of
fluorescent L-PA@N-GQDs.
We express our deep thanks to the Scientific and
Technological Research Council of Turkey (TÜBİTAK)
for financial support (215Z222).
References
[1] Izake E.L., J. Pharm. Sci., 96 (2007), 1659–1676.
[2] Suzuki N. et al., ACS Nano 10 (2016) 1744-1755.
[3] Li X.et al., Adv. Funct. Mater., 25(2015), 4929-47.
[4] Sun J. et al., Part. Part. Syst. Charact., 32 (2015), 434–440.
[5] Wang T.et al., Sci. Reports, 9591 (2015), 1-9.
Poster Presentation – PP0104
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation and Characterization of Biopolymeric Microspheres for Medical
Applications
A. Gülsu1*, H. Ayhan2 and F. Ayhan2
1 Department of Molecular Biology and Genetics, University of Muğla Sıtkı Koçman
2 Department of Chemistry, University of Muğla Sıtkı Koçman
*Presenter: gaydan@mu.edu.tr
Abstract
Cellulosic polymers are widely applied in medicine and
generally regarded as biocompatible. It has wide
ranging applications, e.g. as separation medium, carrier
system and as adsorbent in extracorporeal blood
purification [1-7]. It has also found applications such as
for scaffolds in tissue engineering, temporary skin
substitute, haemostatic agent, postoperative adhesion
barrier, and as a culture material for hepatocytes [8]. As
a biopolymeric material, various forms of cellulose are generally recognized as safe. The aim of this work was
to prepare and characterize cellulose microspheres with
narrow size distribution preferentially in the use for
haemostatic agent, post-operative adhesion barrier, and
drug delivery.
Polysaccharide based cellulose microspheres were
prepared and stabilized by water/organic phase
emulsion system in chitosan media. The influence of
several parameters on the particle size distribution was
assessed. Various processing and formulation
parameters such as stirring speed, volume of processing
medium and evaporation temparature were optimized to have narrow size distribution.
The optical micrographes and SEM images of
biopolymeric microspheres were taken for the
characterization studies after preparation. The prepared
cellulose microspheres were white and spherical in
shape, stable in nature, 2% chitosan concentration, 1400
rpm stirring rate, 40oC solvent evaporation temperature
were determined as optimal conditions. The size
distribution of cellulose microsphere was 5% <2 µm,
80% 3-5 µm, 10% 7-9 µm at these preparation
conditions.
Fig 1. Optical micrograph of cellulose microsheres
Fig 2. SEM photograph of cellulose microsheres
References
[1] de Oliveira W, Glasser WG (1996b) Hydrogels from
polysaccharides. II. Beads with cellulose derivatives. J Appl Polym Sci 61:81–86
[2] Kuga S (1980) New cellulose gel for
chromatography. J Chromatogr 195:221–230
[3] Kaster JA, de Oliveira W, Glasser WG, Velander WH
(1993) Optimization of pressure-flow limits, strength,
intraparticle transport and dynamic capacity by hydrogel
solids content and bead size in cellulose
immunosorbents. J Chromatogr A 648:79–90
[4] Wolf B, Horsch W (1991) Herstellung,
Eigenschaften und Verwendung der Perlcellulose—eine
U ¨ bersicht. Pharmazie 46:392–402
[5] Wolf B, Schmitz W, Schneider H (1996) Composites of bead cellulose and hydrophilic solubiliziers. Int J
Pharm 139: 87–94
[6] Pes ˇka J, S ˇtamberg J, Hradil J, Ilavsky ´ M (1976)
Cellulose in bead form: properties related to
chromatographic uses. J Chromatogr 125:455–469
[7] Volkert B, Wolf B, Fischer S, Li N, Lou C (2009)
Applications of modified bead cellulose as a carrier of
active ingredients. Macromol Symp 280:130–135
[8] Hoenich N (2006) Cellulose for medical
applications.BioResources1(2):270-280
Poster Presentation – PP0105
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Carbon Quantum Dots Embedded Nanopaper for Iodide Sensing
Aylin Arıcı1*, Erhan Zor2, Ahmet O Saf3, Sabri Alpaydin3 and Haluk Bingol3
1 Institute of Science, Necmettin Erbakan University, Konya/Turkey
2 Department of Science Education, Necmettin Erbakan University, Konya/Turkey
3 Department of Chemistry Education, Necmettin Erbakan University, Konya/Turkey
*Presenter: arcaylin@gmail.com
1. Introduction
Nanomaterial engineering technologies have the
potential to revolutionize simple and disposable sensing
systems. In this respect, paper-based (bio)sensors
provide new opportunities and directions in the
development of precise and sensitive analytical devices.
With the recent advances in flexible and transparent
sensor (nano)technology, nanopaper-based sensors have
attracted great attention of researchers [1]. Common
paper is made of cellulose fibers with an average diameter of ~25 µm inducing significant light scattering
that results in an opaque substrate. However, nanopaper
is a transparent film due to the network-forming of
nanocellulose fibers which are several micrometers long
with a diameter below 100 nm. In addition, nanopaper is
capable of adsorbing various kinds of ions, such as
heavy metal ions or cationic dyes, via electrostatic
interaction between functional groups and ions [2]. By
incorporating nanoparticles/dots, nanopaper may exhibit
selective detection of different kind of ions and may
give an analytical signal. Nanopaper-based platforms has been scarcely used for optical (bio)sensing
applications and even no published study exists for
carbon quantum dots embedded photoluminescent
sensors to date. Hence, we sought to fabricate and test a
simple and disposable nanopaper-based sensing
platform for “yes/no” type detection of iodide (I-) anion.
2. Experimental
To prepare nitrogen doped carbon quantum dots (N-CQDs), 0.5 g citric acid was firstly mixed with 55 mg
HMDA. The mixture was heated to 240 ˚C using a
teflon-lined autoclave. Subsequently, the color of the
melting mixture changed from colorless to pale brown.
The resultant N-CQDs solution was purified within the
dialysis bag (MWCO: 2kDa) [3]. PL spectra of the
purified N-CQDs showing excitation and emission
changes were given in Figure 1.
Figure 1 The excitation and emission spectra of N-
CQDs.
Bacterial cellulose nanopaper was fabricated using
Acetobacter xylinum bacteria in 50 g glucose, 5 g yeast
extract, 5 g (NH4)2SO4, 4 g KH2PO4 and 0.1 g
MgSO4.7H2O in 1 liters of water for two weeks at 28 ˚C
[1]. Figure 2 shows SEM images of nanopaper at low
and high magnifications.
Figure 2 SEM images of nanopaper
For sensing experiments, N-CQDs were embedded into
nanopaper by immersing in solution of N-CQDs. Then, paper was dried in drying oven at room temperature.
The resultant N-CQDs-embedded nanopaper was cut to
prepare desired disposable sensors and treated with the
sodium salts of anions (acetate, nitrate, sulfate, fluoride,
chloride, bromide and iodide) by syringing on them. As
easily seen in Figure 3, the green luminescent of N-
CQDs embedded transparent nanopaper was quenched
only in the presence of I- whereas no change was
observed for the other tested anions which demonstrates
that N-CQDs embedded nanopaper could be used as an
effective disposable sensing platform for I- anion.
Figure 3 Nanopaper treated with the sodium salts of the
corresponding anions
References
[1] Morales-Narvàez et al., ACS Nano, 2015, 9 (7),
7296–7305
[2] Mautner et al., Environ. Sci.: Water Res. Technol.,
2016, 2, 117–124.
[3] Liu et al., Nanoscale, 2013, 5, 1810–1815.
Poster Presentation – PP0107
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A High Performance Enzyme-Free Glucose Sensor Based on the Activated
Carbon decorated Ni/Pd Nanocomposites
Fatih Şen1, Yağmur Koşkun1 and Aysun Savk1*
1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupınar University, Kütahya,
Turkey
*Presenter: aysunsavk@gmail.com
Abstract
Herein, an ultrasensitive and reliable non-enzymatic
electrochemical glucose sensor has been developed,
which is based on mesoporous Ni/Pd@AC
nanoparticles prepared by a facile route aided by
ultrasonication under mild conditions [1]. The
fabricated glucose sensor is capable of detecting glucose
with a wide linear region of 0.01–2 mM and an ultralow
detection limit of 10 µM. The Ni/Pd@AC
nanocomposite was characterized by transmission
electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) and UV–
vis spectroscopy [2]. The nanoparticles have also
exhibited favorable properties such as good selectivity,
reproducibility, durability and real sample analysis,
which ensured its potential applications in the clinical
diagnosis of diabetes [3].
Figure 1 . Cyclic voltammograms of NiPd/AC in 0.1 M NaOH of pH 7.0 at different scan rates: (a) 20;
(b) 40; (c) 60; (d) 80; (e) 100; (f) 120; (g) 150; (h)
200 mV/s-1.
References
[1] Wang L, Lu X, Ye Y, Sun L, Song Y (2013) Nickel-
cobalt nanostructures coated reduced graphene oxide
nanocomposite electrode for nonenzymatic glucose
biosensing. Electrochim Acta 114, 484–493.
[2] A.A. Athawale, S.V. Bhagwat, P.P. Katre, (2006);
Nanocomposite of Pd-polyaniline as a selective
methanol sensor, Sensors Actuators B Chem. 114 263–
267.
[3] Wang G, He X,Wang L, Gu A, Huang Y, Fang B,
Geng B, Zhang X (2013) Non-enzymatic electrochemical sensing of glucose. Microchim Acta
180:161–186.
Poster Presentation – PP0108
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Performance Enhancement of Micro-scale Microbial Fuel Cells (µMFC) for
Nanoscale Power Generation
B. Şen Doğan1*, Nilüfer Erkal3, Ebru Özgür3, Özge Zorlu3 and H. Külah2, 3, 4
1 Department of Micro and Nanotechnology, METU,
2 Department of Electrical and Electronics Engineering, METU 3 Mikro Biyosistemler Inc., Ankara
4 METU-MEMS Research and Application Center, Ankara
*Presenter: begum.sen@metu.edu.tr
1. Introduction
µMFCs are small bioreactors converting the energy in
the chemical bonds of organic matter into electrical
energy through catalytic activity of microorganisms
under anaerobic conditions. To obtain higher
performance µMFCs, the internal resistance of µMFC
can be decreased, the start-up time can be decreased or
the biofilm formation quality can be increased. Biofilm
is the complex structure adhering to surfaces that are regularly in contact with liquid substrate (organic
matter) consisting of colonies of bacteria.
2. Design
Optimization of chamber and/or cell geometries,
chamber or electrode materials, and electrode surface
characteristics is crucial to increase µMFC performance.
Thus, MEMS based µMFC electrodes are designed and
fabricated.
µMFC systems are operated under different loads or
open circuit with a Nafion 117 proton exchange
membrane. Shewanella Oneidensis MR-1is preferred to
be the biocatalyst. Triptic Soy Broth is fed as anolyte (3 µL/min) and 100 mM K3[Fe(CN)6] in phosphate buffer
(5 µL/min) is fed as catholyte. With the design given in
Figure 1, the internal resistance is calculated as ~20 kΩ
under these conditions.
Figure 1 Schematic of µMFC
3. Results
The start-up time of the biofilm formation and the effect
of different loads are investigated.
Figure 2 Effect of load on biofilm formation
Table 2 Comparison of performance values
25 kΩ
loaded
10 kΩ
loaded
Qian et al,
2009
Bacteria S. Oneidensis
MR-1
S. Oneidensis
MR-1
S. Oneidensis
MR-1
Anode area 0.61 cm2 0.61 cm2 0.15 cm2
Anode volume 10.4 µL 10.4 µL 1.5 µL
Anode/cathode materials
Au/Au Au/Au Au/carbon cloth
Volumetric power density
133 µW/cm3 26 µW/cm3
15 µW/cm3
Volumetric
current density
716 µA/cm3 500
µA/cm3
670
µA/cm3
Areal power density
2 µW/cm2 0.4 µW/cm2
0.15 µW/cm2
Areal current density
12 µA/cm2 9 µA/cm2 6.7 µA/cm2
4. Conclusions
Acclimatization of µMFC under a load resulted in
shorter start-up time. Power and current densities
obtained is comparable to similar literature study. When
the load is closer to internal resistance of the µMFC,
higher power and current densities are achieved.
References
[1] F. Qian, M. Baum, Q. Gu, and D. E. Morse, “A 1.5
µL microbial fuel cell for on-chip bioelectricity
generation,” Lab Chip, vol. 9, no. 21, p. 3076, 2009.
Poster Presentation – PP0111
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Detection of FV Leiden Mutation with Electrochemical DNA Biosensor
without Indicator
Berrin Tuğrul1*
1Molecular Biology Department, Biology Division, Faculty of Science and Letter, Manisa Celal Bayar University.
Manisa, Turkey
*Presenter: berrin.tugrul@yahoo.com
1. Aim
The method based upon detecting the hybridization
between probe and target sequences without indicator
according to Guanin oxidation signalling in DNA is
defined as identification with electrochemical DNA
biosensor without indicator. This study aimed at
detecting the G → A change in the 1691th nucleotide
of FV gene (FV Leiden) by electrochemical DNA
biosensor without indicator.
2. Material and Method
In this study, PCR products of 224 bp amplified from
FV gene were used. Of 40 PCR products detected by
Restriction Fragment Lenght Polymorphism (RFLP)
method , 20 were heterozygous, 5 homozygous and 20
wild type (Figure 1). Synthetitic oligonucleotides,
random sequence (21 mer belong to HBV), PCR
products diluated in the ratio of 1/40 and denaturated
were hybrydized with carbon paste electrode (CPE) to
whose surface 23 mer probe (wild / mutant) was
attached. Results of hybridization were measured in
differential pulse voltammetry (DPV) between 0.75V
and 1.4V range The consistency of the obtained results
was evaluated statistically by Kappa (к) Methods.
3. Results
The results of Guanin signalling obtained through the
hybridization between the wild type probe with inosine
and target sequences were found as 75-80 nA for wild
type persons, 20-25 nA for heterozygous persons, and
no signalling for homozygous persons (Figure 2). The
results of Guanin signalling obtained through the
hybridization between mutant probe with inosine and
target sequences were determined as no signalling, 20-
25 nA and, 75-80 nA, for wild type, heterozygous and
homozygous persons, respectively (Figure 3). When
compared statistically, the results of electrochemical
DNA biosensor and RFLP were found to be compatible
with each other (kappa (ĸ)=1).
4. Conclusion
FV Leiden mutation, by using electrochemical DNA
biosensor without indicator, could be detected as
heterozygous and homozygous according to different
Guanin signalling.
Keywords: Differential Pulse Voltametry,
Electrochemical DNA biosensor, FV Leiden, RFLP
Figure 1. The results of RFLP obtained from PCR
products. 1. pUC19 DNA/MspI (HpaII) Marker, 23, 2.
PCR product of 224bp., 3. RFLP Product of
homozygous genotype 4, 9. RFLP product of
heterozygous genotype 5, 6, 7, 8. RFLP products of wild
type genotype
Figure 2. Differential pulse voltammograms (A1) and histogram (A2) the results of Guanin signalling
obtained through the hybridization between the wild
type probe with inosine and target sequences
Figure 3. Differential pulse voltammograms (A1) and
histogram (A2) the results of Guanin signalling
obtained through the hybridization between mutant
probe with inosine and target sequences
Poster Presentation – PP0112
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
-0,2 0,0 0,2 0,4 0,6 0,8
0,0
60,0µ
120,0µ
180,0µ
240,0µ
300,0µ
360,0µ
I/A
E/V
A
UA
DA
AA
F
Pt-Co nanoparticles decorated reduced graphene oxide for ultrasensitive dopamine,
ascorbic and uric acid detection
Fatih Sen1, Sait Bozkurt1 and Betül Sen1*
1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupinar University, Kütahya,
Turkey
*Presenter: betul199096@gmail.com
Abstract
Graphene is chemically synthesized by Hummers
method reduction of colloidal dispersions of graphite
oxide [1-2]. Electrochemical characterization of
graphene modified Pt-Co (rGO/Pt-Co) is carried out by
cyclic voltammetry (CV). The behavior of rGO/Pt-Co/GCE towards ascorbic acid (AA), dopamine (DA)
and uric acid (UA) has been investigated by CV,
differential pulse voltammetry (DPV) and
chronoamperommetry (CA). The rGO/Pt-Co/GCE is
successfully used for the simultaneous detection of AA,
DA and UA in their ternary mixture and DA in serum
and pharmaceutical samples. The excellent
electrocatalytic behavior of rGO/Pt-Co/GGE may lead
to new applications in electrochemical analysis [1-2].
Figure: DPV results of AA, DA and UA at GCE,
rGO/Pt-Co modified electrodes.
References
[1] F. Gonan, M. Buda, R. Cespuglio, M. Jouvet, J.-F.
Pujol, In vivo electrochemical detection of catechols in the neostriatum of anaesthetized rats: dopamine or
DOPAC Nature 286 (1980) 902–904.
[2] P. Ramesh, G.S. Suresh, S. Sampath, Selective
determination of dopamine using unmodified, exfoliated
graphite electrodes, J. Electroanal. Chem. 561 (2004)
173–180.
Poster Presentation – PP0113
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A novel sensitive electrochemical sensor based on reduced graphene oxide
decorated Pt nanocomposites for simultaneous determination of uric acid (UA)
Fatih Sen1, Ceyda Ulutürk1 and Betul Sen1*
1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupinar University, Kütahya,
Turkey
*Presenter: betul199096@gmail.com
Abstract
In this paper, Pt -reduced graphene oxide–ZnO (Pt-
ZnO/rGO) nanoparticle composites was prepared by
simple and effective chemical routes. The synthesized
Pt-ZnO/rGO nanoparticle composite has been
successfully applied for glassy carbon electrode (GCE)
surface modification[1]. The Pt-ZnO/rGO nanoparticle -
modified GCE was applied for sensitive and selective
determination of uric acid (UA) [2]. The biosensor
exhibited a linear dependence on UA concentration
ranging from 10 to 750 μM with a detection limit of 0.510 μM (S/N=3). The proposed UA sensor also
showed an excellent stability, reproducibility and anti-
interference property[3-4].
Figure 1 Cyclic voltammograms of the Pt-ZnO/rGO -
modified GCE at scan rate of 20–200mVs−1 in 0.1 M
PBS containing 1mM UA[4].
References
[1] Sun, Z.; Fu, H.; Deng, L.; Wang, J.: Redox-active
thioninegraphene oxide hybrid nanosheet: one-pot,
rapid synthesis, and application as a sensing platform
for uric acid. Anal. Chim.Acta 761, 84–91 (2013).
doi:10.1016/j.aca.2012.11.057
[2]Yang,L.,Liu,D.,Huang,J.S.,You,T.Y.,2014.Sens.Actua
torsB:Chem.193,166–172.
[3] Y.F. Zhao, Y.Q. Gao, D.P. Zhan, H. Liu, Q. Zhao, Y.
Kou, Y.H. Shao, M.X. Li, Q.K. Zhuang, Z.W. Zhu
Talanta, 66 (2005), pp. 51–57 [4] C.F. Tang, S.A. Kumar, S.M. Chen Anal. Biochem.,
380 (2008), pp. 174–183
Poster Presentation – PP0114
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Radiation Synthesis of Superadsorbent Conducting Smart Polymer/Pumice
Nanocomposite Hydrogels
B. Taşdelen1*
1Department of Biomedical Engineering, Namık Kemal University, No:13 59860 Çorlu, Tekirdağ
*Presenter: btasdelen@nku.edu.tr
Abstract
Stimuli-responsive hydrogels with decent electrical
properties are a promising class of polymeric materials
For a range of technological applications, such as
electrical, electrochemical and biomedical devices ction
Smart hydrogels which are sensitive to external stimuli
such as temperature, pH, electric field, magnetic force,
etc. could react actively to environmental changes, thus
receiving increasing attention in recent years [1].
However, traditional smart hydrogels are generally
nonconductive while conductive gels hold great promise for a wide range of applications in sensors, fuels cells,
supercapacitors, dye-sensitized solar cells and lithium
batteries [2]. Polyaniline (PANI) is a well-known
conducting polymer, discovered in the late 19th century
and still under investigation due to the excellent
compromise between favorable properties and cost [4].
Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels are
typical thermosensitive materials. They change their
volume abruptly and significantly on temperature
variations from external environments and exhibit a
lower critical solution temperature (LCST) at about 33°C [3]. Due to their unique properties, PNIPAAm
hydrogels found their applications in chemical devices,
tissue engineering, separation, microfluidic actuators,
biomedical fields. Radiation induced in-situ
polymerization and crosslinking, which can be carried
out at room temperature without initiators and catalysts
are safe, clean and effective method for the synthesis of
the hydrogels Use of pumice for removal of pollutants
by various treatment technologies, mainly adsorption
has become popular during last decade. Turkey has
quite significant potential with respect to pumice
reserves. In this work, semi-IPN poly(acrylamide-co-maleic acid)/polyaniline composite hydrogel was
successfully synthesized by two-steps gamma radiation
induced polymerization in aqueous solution. First,
NIPAAm /itaconic acid (IA) copolymeric hydrogels
were prepared by irradiation of the ternary mixtures of
NIPAAm/IA/water in the presence of pumice by γ-rays
at ambient temperature. Poly(NIPAAm-co-IA)/PANI
hydrogels possessed a high electrical conductivity.
NIPAAm/IA hydrogels were prepared by using gamma
rays irradiation copolymerization of NIPAAm monomer
with addition of an anionic comonomer, namely IA. To prepare highly swollen NIPAAm/IA hydrogel systems,
NIPAAm weighing 10 g was dissolved in 100 mL water
in the presence of pumice. Then, 120 mg of IA were
added to each NIPAAm solution. Monomer solutions
thus prepared were placed in a glass tube with 5 mm
inner diameter. All irradiations were carried out under irradiation in air at dose of 48 kGy at ambient
temperature. Small discs of dry (ca. 0.1 g) of
crosslinked PNIPAAm (homopolymer or copolymer
with IA) hydrogel were immersed in monomer solution
of aniline (AN) in aqueous solution of 1 M HCl (3 mL),
until all the solution was absorbed into the hydrogel
(taking 3 hour at least). These solutions were transferred
to small glass tubes of 5 mm in diameter and irradiated
at dose of 48 kGy in air at ambient temperature under irradiation.
In this work, we study the synthesis of NIPAAm based
hydrogels semi-interpenetrated with polyanilines and
the effect of copolymerization with IA and semi-interpenetration on swelling capacity. We propose a
novel alternative method to incorporate a conductive
linear polymer (PANI) inside a network of pH-sensitive
hydrogel under γ-irradiation at room temperature. In our
study, poly(NIPAAm/IA) three dimensional network is
formed after the first radiation induced polymerization.
Since aniline monomer inside of PNIPAAm network,
the polyaniline chain is formed inside of the
polyacrylamide network during the second
polymerization. The composite hydrogels with good
conductive properties also displayed unique pH and temperature sensitivity. Significantly, the present
findings have tested by embedding a conductive
polymer with a unique morphology via in situ radiation
grafted induced polymerization rather than the usual
blending method would help in the design of drug
delivery systems based on pH and temperature-sensitive
and conductive polymers in biologic media.
Figure 1. Schematic representation of s-IPN
poly(NIPAAm-co-IA)/PANI hydrogels.
References [1] D. Li, X. Zhang, J. Yao, G.P. Simon, H.Wang, Chem. Commun. 2011, 47, 1710. [2] L. Qiu, D.Liu, Y. Wang, C. Cheng, K.Zhou, Adv. Mater,
2014, 26, 3333. [3] Y. Hirokawa, T. Tanaka, J Chem Phys 1984, 81, 6379.
Poster Presentation – PP0115
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Protein Adsorption on SAM Modified SiO2 Surfaces
B. Garipcan1*, and D. Hür2, L. Uzun3, F. Kuralay4 and S. Eren1
1 Institute of Biomedical Engineering, Boğaziçi University,
2 Department of Chemistry, Anadolu University, 3Department of Physics, Chemistry, and Biology, Linköping University
4Department of Chemistry, Ordu University
*Presenter: bora.garipcan@boun.edu.tr
5. Introduction
Protein adsorption is one of the important issues that
can help to understand cell-surface interaction
mechanisms. As the matter of fact that, protein
adsorption is as a precursor of cell-surface interaction
and plays a significant role to indicate biocompatibility
of a biomaterial [1,2]. In this study, novel amino acid
(conjugated histidine, leucine) conjugated self-
assembled molecules (SAMs) were synthesized and
used to modify SiO2 surfaces to investigate protein adsorption.
6. Materials and Methods
Novel amino acid (histidine, leucine) conjugated SAMs
were synthesized in our laboratory, which have special
affinity to SiO2 surfaces and attracted by chemisorption
[4]. Syntheses of amino acid conjugated SAMs were
characterized with H1 - Nuclear Magnetic Resonance
(1H-NMR) Spectroscopy.
SiO2 surfaces were modified 3-(trimethoxysilyl)propane
functional groups conjugated amino acids for (histidine
and leucine), respectively. Substrates were modified in-
situ in flow cell during QCM (SRS, CA, USA)
frequency measurement. 10mM SAM solutions were
used for modifications.
Modified SiO2 surfaces were characterized by water
contact angle measurements and XPS analysis.
It is aimed to manipulate and change the adsorption of
proteins (Albumin, Fibrinogen and Immunoglobulin G)
on the surfaces using amino acid conjugated SAMs.
Protein adsorption was investigated in-situ by using Quartz Crystal Microbalance biosensors. According to
results, target proteins have shown different affinity to
amino acid conjugated SiO2 coated crystals depending
the type of the amino acids and concentration.
7. Results and Discussions
In this study, aim of protein adsorption investigation
part was manipulation of the protein adsorption by
surface modifications. The surface modifications were
proved by QCM frequency measurement, water contact
angle measurement, and XPS analysis before protein
adsorption investigations.
According to results of the protein adsorption study,
fibrinogen has shown the highest affinity to Leu-SAM.
In addition, Leu-SAM has highest affinity for all
proteins than His-SAM. Albumin and IgG have higher
affinity to Leu-Silane than His-Silane.
Figure 1. Fibrinogen adsorption results of 10mM His-Silane
and Leu Silane modified SiO2 surfaces. Δ frequency results (Hz)
in PBS: 7.4 at RT.
8. References
[1] C. Fornaguera, G. Caldero, M. Mitjans M.P. Vinardell, C. Solans,
C. Vauthier, ”Interactions of PLGA nanoparticles with blood
components: protein adsorption, coagulation, activation of the
complement system and hemolysis studies” Nanoscale, 7, 6045-58,
2015
[2] Yang, D., X. Lu, Y. Hong, T. Xi, and D. Zhang, “The molecular
mechanism of mediation of adsorbed serum proteins to endothelial
cells adhesion and growth on biomaterials,” Biomaterials, Vol. 34, pp.
5747–5758, 2013.
[3] C.K. Akkan, D. Hür, L. Uzun, B. Garipcan, “Amino Acid
Conjugated Self Assembling Molecules for Enhancing Surface
Wettability of Fiber Laser Treated Titanium Surfaces”, Applied
Surface Science, 366,
Poster Presentation – PP0251
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A sensitive immunosensor based on indium tin oxide electrodes modified with
carbonyldiimidazole and silane for determination of TNF-α
Burcu Özcan1* and Mustafa Kemal Sezgintürk2
1 Namik Kemal University, Faculty of Arts and Science, Chemistry Department, Biochemistry Division, Tekirdag,
Turkey
*Presenter: burcuozcannku@gmail.com
1. Introduction
Tumor necrosis factor α (TNF-α) is a recognized marker
of the obesity-related inflammatory state [1], and DNA
methylation pattern of its promoter in blood cells is able
to predict the response to a hypocaloric treatment in
humans [2]. TNF-α increases the expression of adhesion
molecules on the endothelium and smooth muscle cells
as has been shown in isolated animal and human
vascular cells [3], and these molecules also impair the
insulin signaling cascade. TNF-α also suppresses insulin signal transduction and expression of the insulin
receptor in isolated adipocytes, which leads indirectly to
glucose dysregulation and hyperglycemia, and eventual
pancreatic β-cell destruction. TNF-α is also associated
with CAD, infarction, stroke, thrombosis and peripheral
arterial disease [4]. Silane coupling agents containing
carboxylate groups may be used to functionalize a
surface with carboxylic acids for subsequent
conjugation with amine containing molecules.
Carboxyethylsilanetriol contains an acetate organo
group on a silanetriol inorganic reactive end. The
silanetriol component is reactive immediately with inorganic –OH substrates without prior hydolysis of
alkoxy groups, as in the case with most other
silanization reagents. Carboxyethylsilanetriol has been
used to add carboxylate groups to fluorescent silica
nanoparticles to couple antibodies for multiplexed
bacteria monitoring [5].
2. Results and Discussion
In this study, a biosensor based on ITO (indium tin
oxide) electrode was designed to determine TNF-α.
Firstly, ITO electrodes were modified with NH4OH/ H2O2/H2O to obtain the OH groups on the surface.
Later, the surface of ITO electrodes were treated with
carboxyethylsilanetriol. After SAM formation, 1,1’-
carbonyl diimidazol was used to interact with carboxyl
groups in carboxyethylsilanetriol solution. Anti- TNF-α
was covalently immobilized on modified ITO
electrodes.
Optimization steps are very important and necessary to
construct a good, stable, repeatable and reproducible
biosensor. For this purpose, all parameters such as
SAMs concentration, 1,1’ carbonyl dimidazol concentration and incubation time, anti-TNF-α
concentration and incubation time were optimized. For
determining the immobilization steps and optimization
of the biosensor, electrochemical impedance
spectroscopy (EIS) and cyclic voltammetry (CV) were
used.
Acknowledgement: This study was supported by The
Scientific and Technological Research Council of
Turkey (TUBİTAK) by the project number of 113 Z
678.
3. References
[1]Odrowaz-Sypniewska G. (2007) Markers of
proinflammatory and pro-thrombotic state in the
diagnosis of metabolic syndrome. Adv Med Sci.
52:246–250
[2] Campion J, Milagro FI, Martinez JA (2009)
Individuality and epigenetics in obesity. Obes Rev
10:383–392.
[3] Lyon CJ, Law RE, Hsueh WA. Minireview:
adiposity, inflammation, and atherogenesis.
Endocrinology 2003; 144: 2195–2200.
[4]Weyer C, Yudkin JS, Stehouwer CD, Schalkwijk CG, Pratley RE, Tataranni PA. Humoral markers of
inflammation and endothelial dysfunction in relation
to adiposity and in vivo insulin action in Pima
Indians. Atherosclerosis 2002; 161: 233–242.
[5]Greg T. Hermanson, Functional Silane Compounds.
Bioconjugate Techniques. Third edition. 2013.
Poster Presentation – PP0117
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Label-free electrochemical immunosensor based on indium tin oxide as a
electrode material for detection of tumor necrosis factor-
Burçak Demirbakan1* and Mustafa Kemal Sezgintürk2
1 Namik Kemal University, Faculty of Arts and Science, Chemistry Department, 2 Biochemistry Division ,Tekirdag, Turkey
*Presenter: burcak_demirbakan@hotmail.com
1. Introduction
Pro-inflammatory cytokine tumor necrosis factor alpha
(TNF-) is a 157-amino acid long polypeptide with an apparent molecular weight of 51 kDa when exists as a
trimer [1,2]. It mediates a variety of cell functions,
including the stimulation of nitric oxide (NO)
production which has been related to oxidative stress and diseases such as stroke, diabetes, severe
meningococcemia, rheumatoid arthritis, and chronic
inflammation [3–4]. Research has shown that TNF- is not produced by normal cells, but rather to be induced
by invasive stimuli in the setting of both endoplastic and
infectious disease. Therefore, the development of
sensitive methods for detection of TNF- is particularly important for biomedical research and clinical
diagnosis. Aldehyde (CHO) functionalities have been
utilized as supports for protein immobilization via
electrostatic and covalent interactions, respectively. The
use of aldehyde termini has the advantage of forming
strong covalent bonds with the primary amines in the
protein residues [5].
2. Result and Discussion
In this study, we designed a novel biosensor to detect
TNF- biomarker constructed on modified indium tin
oxide (ITO) disposable electrodes. Anti- TNF- was immobilized through covalent 11-(triethoxysilyl)
undecanal which formed a self-assembled monolayers
(SAMs) on modified ITO electrodes. Analytical
characteristics such as square wave voltammetry, linear
determination range, repeatibility, reproducibilty and
regeneration of biosensors were determined. All
characterization steps were monitored by Cyclic
Voltammetry (CV), and Electrochemical Impedance
Spectroscopy (EIS) techniques. To achieve reproducible
and repeatable biosensor system, all parameters such as
SAMs concentration, antibody concentration and antibody incubation time were optimized. The presented
biosensor has wide determination range (5 fg-75
fg/mL).
This study illustrates development of the biosensor for
the determination of tumor necrosis factor alpha (TNF-
). For this purpose, firstly the biosensor was based on indium tin oxide (ITO) disposable electrodes modified
with 11-(triethoxysilyl) undecanal. Cyclic
voltammetry (CV) and electrochemical impedance
spectroscopy (EIS) methods were applied to
characterize the immobilization of anti- TNF- process
and to determine TNF-. Analytical characteristics such as square wave voltammetry, linear determination
range, repeatibility, reproducibilty and regeneration of
biosensors were determined. For expounding binding
characterization of TNF- and anti- TNF- single frequency impedance method was utilized. Scanning
electron microscopy was used for identifying the
surface morphology and Kramers-Kronig transform was
implemented on impedance datum. The biosensor has exhibited good repeatability and reproducibility. Linear
range of developed biosensor was 0.03 pg – 3 pg/mL.
To verify the availability of the biosensor, the human
serum samples were experienced.
Acknowledgement: Authors are thankful The Scientific
and Technological Research Council of Turkey
(TUBİTAK) by the project number of 113 Z 678.
References
[1] F. Bettazzi, L. Enayati, I.C. Sanchez, R. Motaghed,
M. Mascini, I. Palchetti, Electrochemical bioassay for
the detection of TNF-alpha using magnetic beads and
disposable screen-printed array of electrodes,
Bioanalysis 5 (2013) 11–19. [2] Y. Liu, W. Zhang, X. Yu, H.W. Zhang, R. Zhao, D.
Shangguan, Y. Li, B.F. Shen, G.Q. Liu, Quartz crystal
biosensor for real-time kinetic analysis of interaction
between human TNF-alpha and monoclonal antibodies,
Sens. Actuators B Chem. 99 (2004) 416–424.
[3] Y. Liu, Q. Zhou, A. Revzin, An aptasensor for
electrochemical detection of tumor necrosis factor in
human blood, Analyst 138 (2013) 4321–4326
[4] R. Say, S.E. Diltemiz, S. Celik, A. Ersoz, Nanolabel
for TNF-alpha determination, Appl. Surf. Sci. 275
(2013) 233–238. [5]. A. Riposan, Y. Li, Y. H. Tan, G. Galli, G. Liu,
Structural Charactrerization of Aldehyde-Terminated
Self-Assembled Monolayers, Department of Chemistry
111 (2007) 12727-12739.
Poster Presentation – PP0118
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation and Enzymatic Application of a Time Dependent Growth of
flower-like hybrid nanoflowers by horseradish peroxidase
Cevahir Altinkaynak1,2*, Melike Vecihe Koc1, Nalan Özdemir3 and Ismail Ocsoy1,2
1 Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey
2 Nanotechnology Research Center, Erciyes University, Kayseri, 38039 Turkey 3 Department of Chemistry, Faculty of Science, Erciyes University, Kayseri, 38039 Turkey
*Presenter: akcevahir@gmail.com
1. Introduction
Enzymes which catalyze reactions with high specificity
and very high rapidity are biocatalysts. Free forms of
enzymes have a short life time and this situation limites applications of enzymes in many areas. In order to
increase the stability, catalytic activity and reusability of
enzymes, many different immobilization methods are
used for this purpose. Recently, nanoflowers has gained
attention because the organic-inorganic hybrid
nanostructures present higher stability and activity
compared to free forms [1]. In this study, time
dependent growth of flower-like hybrid nanoflowers
(hNFs) were observed using HRP (Horseradish
peroxidase) enzyme as the organic portion and
CuSO4.5H2O as inorganic components. Then some characteristics of these synthesized nanostructures were
determined. To prove formation of mechanism, we have
tested different incubation times. And the main
controlling factors on the morphology were
investigated.
2. Experimental
The hybrid nanoflowers were synthesized using a
reported method [1,2,3] (Fig.1). First, CuSO4 stock
solution was prepared in ultrapure water. Then, certain
volume of that solution was added to PBS solution
containing 0.02 mg mL-1 HRP. The resulting mixture
was vigorously shaken for 30 seconds and incubated without disturbing at +4°C for 1, 3, 6, 12, 24, 48 and 72
hours. After incubation, the blue color precipitates were
collected and washed by centrifugation at 4000 rpm for
15 minutes. The washing process was repeated at least 3
times. The collected precipitates were dried 50°C under
vacuum. The structure of the synthesized hNFs was
confirmed by FT-IR, XRD, and EDX. The enzymatic
activities of hNFs and free horseradish peroxidase were
determined by measuring colorimetric and
spectroscopic methods using guaiacol as a substrate in
PBS buffer (pH 6.8).
Figure 1 The growth mechanism of hybrid nanoflowers
(A) nucleation and formation of primary crystals, (B)
growth of crystals (C) formation of nanoflowers
3. Results and Discussion
SEM images of synthesized hNFs were given in Fig.2.
Encapsulation yields of hybrid nanostructures were
calculated by determining HRP concentration in the supernatant (Table 1).
Table 1. The encapsulation yield of HRP hybrid
nanostructures
Different
incubation time
Protein Concentration
(mg/ml)
Encapsulation
Yield (%) Initial After
incubation
1 h
0,02
0,0060 70
3 h 0,0052 74
6 h 0,0042 79
12 h 0,0030 85
24 h 0,0022 89
48 h 0,0012 94
72 h 0,0004 98
Figure 2 SEM images of the
nanostructures (A) 1h (B) 3h (C)
6h (D) 12h (E) 24h (F) 48h (G)
72h
Most regular and uniform flower-shaped morphology
was observed at a 72h incubation. The nanoflower
exhibited the highest activity (120,39 EU/mg) compared
the free HRP (33,48 EU/mg) and nanoflower formed in
other incubation times. With these features, HRP has
been used in different scientific and technical
applications, such as removal of phenols from polluted
water, and biosensor design.
4. References [1] J. Ge, J. Lei and R.N. Zare, Nature Nano. 2012, 7, 428–432.
[2] B. Somtürk, M. Hançer, I. Ocsoy and N. Özdemir, 2015, Dalton Transactions
[3] C. Altinkaynak, İ. Yilmaz, Z. Koksal, H. Özdemir, I. Ocsoy, N. Özdemir, International
Journal of Biological Macromolecules, 84, 402-409 (2016).
Poster Presentation – PP0119
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
0
200
400
Re
lavi
te A
ctiv
ity
(%)
Lipase-Cu+2 Lipase-Fe+2
Lipase-Zn+2
Synthesis of Lipase Based Hybrid Nanoflower through the Coordination
Chemistry and Their Excellent Activity
Cevahir Altinkaynak1,2*, Mehmet Yasar Dinler1, Nalan Özdemir3 and Ismail Ocsoy1,2
1 Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey
2 Nanotechnology Research Center, Erciyes University, Kayseri, 38039 Turkey 3 Department of Chemistry, Faculty of Science, Erciyes University, Kayseri, 38039 Turkey
*Presenter: akcevahir@gmail.com
1. Introduction
As natural biocatalysts, enzymes have received
considerable attention owing to their unique properties,
including high catalytic activity, stability, selectivity,
low toxicity and water-solubility. Accordingly, they
have found widespread use in various scientific and
technical fields, including chemistry, biochemistry,
medicine, pharmaceutical science and industry [1-3].
However, the instability of the free enzymes in aqueous
solution strictly limits their applications. To address this
issue, two common methods, chemical modification and
immobilization, have been used to enhance enzyme catalytic activity and stability. Recently, Zare and co-
workers reported an elegant approach for the synthesis
of immobilized enzymes in the form of nanoflower with
highly enhanced catalytic activity and stability [1].
These flower-like hybrid nano structures are developed
and used for various applications. In this study, lipase hybrid nanostructures were prepared
using different metal ions (Cu+2, Fe+2, Zn+2) and some
characteristics of them were determined. They can be
commonly used as components in kits for medical
applications and biosensors.
2. Experimental
The synthesis of nanostructures were accomplished
using a described method before [1,3,4]. In this
synthesis strategy, metal ions especially Cu2+ were
rationally and successfully combined with lipase to
form flower-like hybrid structures called “hybrid
nanoflowers (hNF)”. The proposed mechanism of
lipase-Cu+2 hNF formation is illustrated in Fig. 1.
Figure 1 Schematic illustration of the preparation
of hybrid nanoflowers
The structure of the synthesized lipase nanostructures
were scanned via SEM and characterized by FT-IR,
XRD, and EDX.
The catalytic activity of synthesized lipase nano
structures were evaluated by hydrolysis of olive oil and
oleic acid concentration was measured.
3. Results and Discussion
Encapsulation yields of lipase hybrid nanostructures
(0.1 mg mL-1) were calculated by determining lipase
concentration in the supernatant (Table 1).
Table 3 The encapsulation yield of lipase hybrid
nanostructures
Type Encapsulation Yield (%)
Lipase-Cu+2
93,11
Lipase-Fe+2
81,63
Lipase-Zn+2
87,37
The morphology of the lipase hybrid nanostructures
were demonstrated with SEM images in Fig. 2.
Figure 2 SEM images of the nanostructures (A)
Lipase-Cu+2 (B) Lipase-Fe+2 and (C) Lipase-Zn+2
The activity of the immobilized enzyme was higher than
the free enzyme. According to the free lipase enzyme;
Lipase 221.90% Zn-Fe-lipase 175.61% and 128.27% Cu
lipase showed greater of the activity.
At the end of 8 measurements it was found to be reused 60-80%.
4. References [1] J. Ge, J. Lei and R.N. Zare, Nature Nano. 2012, 7, 428–432.
[2] A. Atasever, H. Ozdemir, I. Gulcin, O. I. Kufrevioglu, Food Chem., 2013, 136, 864-870.
[3] B. Somturk, M. Hancer, I. Ocsoy and N. Özdemir, 2015, Dalton Transactions
[4] C. Altinkaynak, I. Yilmaz, Z. Koksal, H. Özdemir, I. Ocsoy, N. Özdemir, International
Journal of Biological Macromolecules, 84, 402-409 (2016).
Poster Presentation – PP0120
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Synthesis of Catecholamine-Metal İons Coordinated Hybird
Nanoflowers and Their Catalytic, Antioxidant and Antimicrobil
Properties
Çağla Çelik1* and Ismail Ocsoy1
1Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey
*Presenter: caglcel@gmail.com
Abstract
Herein we report the preparation of organic–inorganic
nanoflowers formed of catecholamines and metal ions using a newly developed and an elegant immobilization
approach. While copper (II)/iron (II) metal ions were
used as inorganic component, epinephrine,
norepinephrine and dopamine were utilized as the
organic component. We also demonstrated how
dopamine (DA) based hybrid nanoflowers (HNFs) acted
as catalytic, antioxidant and antimicrobial agents. The
catalytic performances of DA-Cu2+ and Fe2+ HNFs were
evaluated as peroxidase-enzyme by oxidation of
guaiacol (2-methoxyphenol) to 3,3-dimethoxy-4,4-
diphenoquinone in the presence of hydrogen peroxide (H2O2) based on Fenton-like reaction. DA-Fe2+ HNFs
exhibited antioxidant activity towards 2,2-diphenyl-1-
picrylhydrazyl (DPPH). Finally, we also used the DA-
Cu2+ and Fe2+ HNFs as antimicrobial agent against
bacterial pathogens (Gram+ bacteria Staphylococcus
aureus and Gram- bacteria Escherichia coli) and fungal
pathogen (Candida albicans). We claim that HNFs
produced with this synthesis approach can be empolyed
in fabrication of biosensors and bioanalytical tools and
can be used in various scientific and technical fields.
Figure 1. (1) Illustration of plausible formation
mechanism of catecholamines–Metal2+ HNFs formed in
typical three successive steps (nucleation, growth and
completion). Potential uses ofthe HNFs as (2) catalytic,
(3) antioxidant and (4) antimicrobial agents.
Note: DA, E and NE represent dopamine and
epinephrine, norepinephrine, respectively
5. References
[1] J. Ge, J. Lei, R.N. Zare, Protein–inorganic hybrid
nanoflowers, Nat. Nanotechnol. 7 (2012) 428–432.
[2] Z. Wu, X. Li, F. Li, H. Yue, C. He, F. Xie, Z. Wang,
Enantioselective transesterification of (R,S)-2-pentanol
catalyzed by a new flower-like nanobioreactor, RSC
Adv. 4 (2014) 33998.
[3] B. Somturk, M. Hancer, I. Ocsoy, N. Özdemir,
Synthesis of copper ion incorporated horseradish
peroxidase-based hybrid nanoflowers for enhanced
catalytic activity and stability, Dalton Trans. 44 (2015)
13845–13852. [4] I. Ocsoy, E. Dogru, S. Usta, A new generation of
flowerlike horseradish peroxides as a nanobiocatalyst
for superior enzymatic activity, Enzyme Microbiol.
Technol. 75–76 (2015) 25–29.
[5] B. Somturk, I. Yilmaz, C. Altinkaynak, A. Karatepe,
N. Özdemir, I. Ocsoy, Synthesis of urease hybrid
nanoflowers and their enhanced catalytic properties,
Enzyme Microbiol. Technol. 86 (2016), 134–142.
[6] C. Altinkaynak, I. Yilmaz, Z. Koksal, H. Özdemir, I.
Ocsoy, N. Özdemir, Preparation of lactoperoxidase
incorporated hybrid nanoflower and its excellent
activity and stability, Int. J. Biol. Macromol. 84 (2016) 402–409.
[7] C. Altinkaynak, S. Tavlasogluc,, N. Özdemir, I.
Ocsoy, A new generation approach in enzyme
immobilization: Organic-inorganic hybrid nanoflowers
with enhanced catalytic activity and stability, Enzyme
Microbiol. Technol. 93 (2016) 105–112.
Poster Presentation – PP0206
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
“Label-free impedimetric aptasensor for Ochratoxin‑A detection using Iridium
Oxide nanoparticles”
Lourdes Rivas1,2, Carmen C. Mayorga-Martinez1, Daniel Quesada-Gonzalez1*, Alejandro Zamora-Galvez1, Alfredo de
la Escosura-Muniz1 and Arben Merkoçi
1,3
1ICN2- Nanobioelectronics & Biosensors Group, Institut Catala de Nanociencia i Nanotecnologia, Campus UAB,
08193 Bellaterra (Barcelona), Spain 2Department de Quimica, Universitat Autonoma de Barcelona, 08193, Bellaterra (Barcelona), Spain
3ICREA- Institucio Catalan de Recerca i Estudis Avançatsi 08010 Barcelona, Spain
*Presenter: daniel.quesada@icn2.cat
Abstract
Ochratoxin A (OTA) is a mycotoxin generated by
different fungi species such as Aspergillus and Penicillium during their growth. This toxin is a
hazardous contaminant present in a great number of
agricultural products such as cereals, coffee beans, dried
fruits, cocoa, nuts, beer and wine, causing economic
losses to agricultural trade [1]. Different methods are
routinely used for analysis of mycotoxins, such as
chromatography, enzyme-linked immunosorbent assay
(ELISA), and lateral flow assays (LFA), but label-free
and highly sensitive methods are still strongly required.
In this context, we present here [2] a novel aptasensor
for ochratoxin A (OTA) detection based on a screen-
printed carbon electrode (SPCE) modified with polythionine (PTH) and iridium oxide nanoparticles
(IrO2 NPs) [3, 4], which exhibit good stability,
biocompatibility and catalytic properties. The
electrotransducer surface is modified with an
electropolymerized film of PTH followed by the
assembly of IrO2 NPs on which the aminated aptamer
selective to OTA is exchanged with the citrate ions
surrounding IrO2 NPs via electrostatic interactions with
the same surface. Electrochemical impedance
spectroscopy (EIS) in the presence of the [Fe(CN)6]−3/−4
redox probe is employed to characterize each step in the aptasensor assay and also for label-free detection of
OTA in a range between 0.01 and 100 nM, obtaining
one of the lowest limits of detection reported so far for
label-free impedimetric detection of OTA (14 pM; 5.65
ng/kg). The reported system also exhibits a high
reproducibility, a good performance with a white wine
sample, and an excellent specificity against another
toxin present in such sample.
References:
1. Food and Agricultural Organization (FAO). Manual
on the application of the HACCP system in mycotoxin prevention and control; FAO: Rome, 2001; p 124.
2. Rivas, L.; Mayorga-Martinez, C.; Quesada-Gonzalez,
D.; Zamora-Galvez, A.; de la Escosura-Muniz, A.;
Merkoçi, A. Anal. Chem. 2015, 87, 5167−5172.
3. Mayorga Martinez, C.; Pino, F.; Kurbanoglu, S.;
Rivas, L.; Ozkan, S.; Merkoçi, A. J. Mater. Chem. B
2014, 2, 2233−2239.
4. Rivas, L.; de la Escosura-Muniz, A.; Pons, J.;
Merkoçi, A. Electroanalysis 2014, 26, 1287−1294.
Poster Presentation – PP0122
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation of Carbon Paste Electrode containing Polyaniline-Activated
Carbon Composite for Amperometric Detection of Phenol
Halit Arslan1, Derya Yücel
2, Bekir Sıtkı Çevrimli
3, Hüseyin Zengin
4, Demet Uzun
1* and Fatma Arslan
1
1Department of Chemistry, Faculty of Sciences, Gazi University, 06500, Ankara, Turkey
2 Department of Chemistry, Institute of Sciences, Gazi University, Ankara, Turkey 3Department of Chemical Technology, Ataturk Vocational College, University of Gazi, 06500 Ankara, Turkey,
4Department of Chemistry, Faculty of Arts and Sciences, Gaziantep University, Gaziantep, Turkey
*Presenter: demetuzun@gazi.edu.tr
Abstract
Carbon paste electrodes are widely used in electro analysis owing to their low background current, wide
potential window, chemical inertness, simple, and fast
preparation from inexpensive materials. [1]. A large
variety of phenolic compounds exists. Some of them
may have harmful effects for the health. Their accurate
determination is of great importance due to their toxicity
and persistency in the environment, and the detrimental
effect of phenols on human health requires a strict
directive for the identification and quantification of such
compounds [2, 3]. In this study, a novel carbon paste
electrode using the salt form of polyaniline (pani)-
activated carbon composite sensitive to phenol, was prepared.
1. Materials and Methods
Polyphenol oxidase (tyrosinase) enzyme was
immobilized onto carbon paste electrode containing
polyaniline-activated carbon by cross-linking with
glutaraldehyde. The amperometric determination is
based on the electrochemical reduction of o-quinone
generated in the enzymatic reaction of phenol at -0.15 V
vs. Ag/AgCl. Scheme 1 shows reaction for the phenol
determination.
2. Results and Discussion
In this study, a novel carbon paste electrode using the
salt form of polyaniline (pani)-activated carbon
composite sensitive to phenol, was prepared. The effects
of pH and temperature were investigated and optimum
parameters were found to be 8.0 and 45 °C,
respectively. The linear working range of the electrode
was 1.0×10-6 - 5.0×10-5 M, R2 =0.982. The storage
stability and operation stability of the enzyme electrode
were also studied.
Scheme 1 Reaction scheme for the detection of phenol
References
[1] Arduini, F., Giorgio, F.Di., Amine, A., Cataldo, F.,
Moscone, D., and Palleschi, G. (2010). Electroanalytical
Characterization Of Carbon Black Nanomaterial Paste
Electrode: Development Of Highly Sensitive Tyrosinase Biosensor For Catechol Detection. Analytical Letters,
43, 1688–1702.
[2] Hervas Pérez, J.P., Sanchez-Paniagua López, E.,
López-Cabarcos, M., López-Ruiz, B. (2006)
Amperometric tyrosinase biosensor based on
polyacrylamide microgels. Biosensors and
Bioelectronics, 22, 429–439.
[3] Rogers, K.R., Becker, J.Y., Wang, J., Lu, F., (1999).
Determination of phenols in environmentally relevant
matrices with the use of liquid chromatography with an
enzyme electrode detector. Field Anal. Chem. Technol., 3(3), 161–169.
Poster Presentation – PP0121
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Gold Modified Anisotropic Titanium Nanorod arrays for Sensing Applications
D.Ş. Özden1*, M. Yılmaz2, E. Pişkin1, G. Demirel3
1 Department of Bioengineering Chemical Engineering Department and Bioengineering Division, Center for
Bioengineering and Biyomedtek/Nanobiyomedtek, Hacettepe University, 06800, Beytepe, Ankara, Turkey 2 Engineering and Architecture Faculty, Bioengineering Department, Sinop University, 57000, Sinop, Turkey
3 BIMREL Research Group, Department of Chemistry, Gazi University, Turkey
*Presenter: dlkozden@gmail.com
1. Introduction
Nanostructured titanium has become of great
importance in the development of functional materials
which could be used in photocatalysis, sensing, photovoltaics, water splitting, lithium ion batteries and
tissue engineering. Among the various oxide and non-
oxide 3-D nanostructured materials, titanium nanorods
(TiNRs) have also attracted increasing attention due to
their unique features [1]. Here, we demonstrated a
simple method to fabricate directional 3-D titanium
nanorod arrays through an oblique angle vapor
deposition approach. By combining fabricated TiNR
arrays with a thin layer of gold, they were utilized in
plasmonic catalysis and sensing applications.
2. Experimental
The glass slides or silicon wafers were first cut
(2.5x2.5 cm) and washed with deionized water, acetone,
and piranha solution consecutively. To eliminate any
contaminants, pre-cleaned surfaces were then treated
with oxygen plasma at low pressure (0.2 mbar) for 30
min before titanium deposition. The directional titanium
nanorod arrays were fabricated in a physical vapor
deposition (PVD) system (NANOVAK HV, Ankara,
Turkey) using a homemade OAD equipment. The
thickness of deposited films was monitored using an
Inficon XTM/2 deposition monitor with 0.5% sensitivity. Base pressure was gained by using a
mechanical pump (Edwards E2M2 model, up to 10-3
Torr) and a turbo pump (Turbovac 50, up to 10-6 Torr)
and monitored via a Terranova Model 934 Wide Range
Vacuum Gauge Controller. During deposition, the base
pressure was almost fixed at ~10-6 Torr with a titanium
evaporation rate of 0.1 Å s-1 [2]. The directional titanum
nanorods were created at different deposition angles to
manipulate their surface densities.
2. Results and Discussion
Figure 1 shows the top-view and cross-sectional SEM
images of fabricated TiNRs. It is clear that the TiNRs
are uniform and vertically aligned to the glass surface.
The length of the fabricated TiNRs were analyzed by
employing freeware ImageJ software and determined to
be 1.92 ± 0.05 µm.
Figure 1. Top-view (a) and cross-sectional (b) SEM
images of fabricated TiNRs and (c) cross-sectional
(d) top-view images of Au thin film coated TiNRs.
Gold deposition was performed in PVD as thin film
with different thickness such as 10, 20, 30 nm.
Moreover, the effect of calcination of surface modified
titanium nanorods were examined by using different
temperatures such as 300, 450, 500, 600, 750 °C [3]. Specifically, we studied the dewetting of gold films on
TiNR arrays. To investigate the SERS activity, the
raman enhancement properties were measured.
As a result, we showed the formation of titanium nanorod structures with PVD-OAD technique. Our
results indicated that the SERS activity for gold
deposited TiNRs can be manipulated through annealing
temperature.
Ackowledgement: This work was supported by Gazi
University (05/2015-19).
References
[1] Yu et al. Applied Catalysis B: Environmental, 2009,
90, 595–602. [2] Yılmaz et al. Phys. Chem. Chem. Phys., 2014, 16,
5563.
[3] Schaefer et al. Acta Materialia, 2013, 61, 7841–7848
Poster Presentation – PP0126
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Removal of Toxic Metals by using Janus Micromotors
D. A. Uygun1,2*, B. Jurado-Sanchez1, M. Uygun1,2 and J. Wang1
1Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093, USA
2Department of Chemistry, Adnan Menderes University, Aydın, Turkey
*Presenter: daktasuygun@gmail.com
1. Introduction
Heavy metal pollution has been accelerated dramatically
since the industrial revolution, and is currently posing
major environmental and human health concerns. Such
widespread use has resulted in substantial accumulation
of toxic heavy metals in the environment and living
organisms. Therefore, the removal and detoxification of
metals, such as lead, cadmium, thallium, mercury, and
arsenic has attracted a considerable recent attention [1].
Advances in nanotechnology have opened new horizons
for addressing metal remediation demands due to the unique properties of nanosized materials, e.g., extremely
high surface area, high catalytic and antimicrobial
properties and tunable surface chemistry.3 Recently
developed meso-2,3-dimercaptosuccinic acid (DMSA)-
iron oxide nanoparticles display high capacity and
selectivity for softer heavy metals in water samples [2].
Here we describe high-speed metal chelation and
removal using self-propelled ligand-functionalized
water-powered micromotors. The autonomous
propulsion of synthetic micromotors through fluid
environments is one of the most exciting fields of nanotechnology [3]. The new self-propelled chelation
platforms described here are based on fuel-free Mg
Janus-micromotors, functionalized with DMSA, for
efficient removal of heavy metals from environmental
and biological media
2. Methods
The micromotors were prepared using magnesium
microparticles as the base particles and one half of
microparticles were coated with a 100 nm Ti layer and a
10 nm gold layer. External gold surface of microparticles was modified by overnight incubation of
meso-2,3-dimercaptosuccinic acid.
Zn, Cd and Pb amounts were measured
electrochemically. For this, stripping voltammetric
measurements were performed with an “in situ” co-
deposition of a bismuth film and the target metals in the
presence of dissolved oxygen
3. Results
The new micromotors were prepared by half-coating
Mg microparticles (average diameter 20 μm) with Ti
and Au layers. The scanning electron microscopy
(SEM) images of Fig. 1, reveal the spherical Janus
structure of the resulting micromotor, indicating that it
maintains its structure after the modification process.
Figure 1 SEM images showing the Janus structure
before (a) and after (b) dissolution of the Mg
core.
Fig. 2 displays the effect of the treatment time upon the
motor induced removal of Z(II), C(II) and P(II). A
dramatic decreases of the initial response of these heavy
metal ions (a), corresponding to 85% (Zn and Cd) to
99% (for Pb) removal, is observed following a 3 min
treatment with the Mg/Ti/Au/ DMSA micromotor (d).
Longer navigation times result in the complete removal
of these metal ions from the contaminated samples (e).
In contrast, no apparent change in the metal
concentration is observed in the presence of the moving
unmodified (ligand-free) micromotors.
Figure 2 Effect of the navigation time on the
removal of Zn(II), Cd(II) and Pb(II) by
Mg/Ti/Au/DMSA micromotors.
4. References
[1] F. Fu and Q. Wang, J. Environ. Manage., 2011, 92,
407.
[2] W. Yantasee, C. L. Warner, T. Sabgvanich, R. S.
Addleman,T. G. Carter, R. J. Wiacek, G. Fryxell, C.
Timchalk and M. Warner, Environ. Sci. Technol., 2007,
41, 5114. [3] J. Wang, Nanomachines: Fundamentals and
Applications, Wiley-VCH, Weinheim, Germany, 2013,
ISBN 978-3-527-33120-8.
Poster Presentation – PP0210
Poster Presentation – PP0126
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Reliability and sensitivity of paper-based glucose sensing: comparison of sensing
mechanisms Deniz Baş1*
1 Nanobiosensing & Food Safety Research Group, Department of Food Engineering, Çankırı Karatekin University,
Çankırı, 18100, Turkey
*Presenter: denizbas@gmail.com
1. Introduction
Paper-based sensing platforms are promising due to
their low-cost and easy-to-use structure [1]. The sensing
principle mostly based on colorimetric read-out. Until a
few years back, paper-based platforms/assays are only
used for qualitative measurements. By implementing
specific colorimetric reactions and the usage of
optoelectronic devices i.e. scanners, cell phones etc,
paper-based platforms became important for
quantitative sensing for point-of-care diagnostics.
Herein, two glucose sensing mechanisms were
compared and reliability and sensitivity of the methods were investigated.
2. Materials and Method
Preparation of sensing platform: Design of the patterns
was performed by opensource software Inkscape 0.91
(www.inkscape.org). Patterns were printed on the filter
papers (Sartorius Stedim, quantitative filter, particle
retention 12-15 µm). Finally, hydrophobic channels
were obtained by painting with permanent ink marker
(Edding 141F).Glucose measurements: Glucose,
glucose oxidase (GOx), peroxidase (POD), phenol,
potassium iodide (KI), 4-aminoantipyrine (4-AA) were purchased from Sigma-Aldrich (Germany). Two
different glucose sensing mechanisms (Hata! Başvuru
kaynağı bulunamadı. and Hata! Başvuru kaynağı
bulunamadı.) were used and for both mechanisms the
specific reaction between glucose and glucose oxidase
enzyme is the common step. Mechanisms differ from
each other according to the reaction of hydrogen
peroxide with the chromagens.
Scheme 1. Glucose assay based on iodine formation
Scheme 2. Glucose assay based on the quinone dye
formation
For iodine formation reaction, 300 U/ml GOx, 500 U/ml
POD and 0.6 M KI mixture and for quinone dye
formation 300 U/ml GOx, 500 U/ml POD, 1 M phenol
and 0.1 M 4-AA mixture was used as test solution. For
visual detection; 2 µl of test solution was pipetted onto
test zones and dried at room temperature. Glucose assay
was performed by pipetting 2 µl of standard glucose
solutions to the test zones. Finally, quantitative glucose
measurement was performed by the reading the L*a*b
color space values and sensitivity of the mechanisms
was investigated.
3. Results and Discussion
Comparison of glucose sensing strategies: As a result of
quionone dye formation mechanism, color development
is uniform when compared with iodine formation reaction (Figure 1) and the color intensity is higher.
Uniformity of color developed by quionone dye
formation increases the reliability of glucose sensing
and higher color intensity lowers the limit of detection.
Figure 1. Paper-based glucose sensing A) Quinone dye
formation B) iodine formation
Limit of detection (LOD) values for glucose were
determined as ~0.5 mM and ~1 mM for quinone and
iodine formation, respectively. LOD for quinone
method on paper platform is also lower than the LOD
value of same method performed by spectrophotometer.
The stability of the quinone dye formation mechanism
was investigated for about 40 days. For this purpose;
test solution was pipetted onto test zones and paper
platforms were stored at room temperature by avoiding
interaction with the ambient light. Test platform is
stabile for 30 days. On the other hand, iodine method is
not stabile and in almost 3 days, a drastic decrease had been observed. Moreover, results obtained by using
scanner and cell phones (Android and iosX) were
investigated and performance of platforms were
determined.
4. References
[1] A.W. Martinez, S.T. Phillips, M.J. Butte, G.M.Whitesides, Patterned
paper as a platform for inexpensive, low-volume, portable bioassays,
Angew. Chem. Int. Ed. 46 (2007) 1318–1320.
Poster Presentation – PP0123
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical determination of interaction between DNA and anticancer drug
capecitabine by using DNA modified carbon paste electrodes
D. Kiziloluk1*, G. Gökçe2, Ş. Çetinus1 and A. Erdem3
1Cumhuriyet University, Faculty of Science, Department of Biochemistry, Sivas, TURKEY
2Cumhuriyet University, Faculty of Education, Department of Elementary Science, Sivas, TURKEY 3Ege University, Faculty of Pharmacy, Department of Analytical Chemistry, Izmir, TURKEY
*Presenter: deryakiziloluk@cumhuriyet.edu.tr
Abstract Recently there has been an increasing attention to detect
the interaction between DNA and anticancer drugs by
using biosensor technologies 1. In this study, it was investigated that the interaction between capecitabine
which is anti cancer drug, and DNA by electrochemical
methods in combination with carbon paste electrode
(CPE). The interaction between capecitabine and the
single stranded DNA (ssDNA) and double stranded
DNA (dsDNA) obtained from calf thymus (ct dsDNA)
was investigated by monitoring the differences at the
guanine oxidation signals. The experimental parameters
such as the concentrations of ct DNA and drug, and also
the interaction time were optimized. The detection limit was estimated and the results were comprised
repeatability of carbon paste electrode. It was also
confirmed that ct DNA had immobilized onto electrode
surfaces by impedimetric measurements using
electrochemical impedance spectroscopy technique 2,
3.
Ct dsDNA and ct ssDNA were immobilized onto the
electrode surface, and accordingly the voltammograms
were recorded. It was observed that there was an
increase at the oxidation signal of guanine 4.
In the case of DNA interaction with capecitabine, there
was a decrease at guanine signal. Thus, it could be
explained as the result of interaction between DNA and
capecitabine. It was tested that interaction between capecitabine and ct dsDNA or ct ssDNA separately
using carbon paste electrode 5.
The calibration graphs were plotted between the
concentration of capecitabine and guanine oxidation
current in order to determine the detection limits. The
detection limit (DL) was estimated of carbon paste
electrode for ct ssDNA and ct dsDNA and found to be
17, 12 μg/mL and 17, 35 μg/mL respectively 6.
As a result, it is concluded that the proposed method
could be used furtherly for elucidation of the interaction
between the newly synthesized molecules and DNA.
Key Words:
Electrochemical DNA Biosensor, Capecitabine, Carbon
Paste Electrode, Differential Puls Voltammetry,
Electrochemical Impedance Spectroscopy.
Acknowledgements: This work is supported by the
Scientific Research Project Fund of Cumhuriyet
University under the project number F-387.
References
1 Wang, L., Lin, L., Ye, B. (2006). Electrochemical studies of the interaction of the anticancer herbal drug
emodin with DNA, Journal of Pharmaceutical and
Biomedical Analysis, 42: 625–629.
2 Erdem, A., Özsöz, M., (2001). Interaction of anticancer drug, Epirubicin with DNA, Analitica
Chimica Acta, 437, 107-114.
3 Wang, J., Flechhsig, G., Erdem, A., Korbut, O., Gründler, P. (2004). Label-free DNA Hybridization
based on coupling of a heated carbon paste electrode
with magnetic separations, Electroanalysis, 16 (11),
928-931.
4 Erdem, A., Özsöz, M. (2002). Review: Electrochemical DNA biosensors based on DNA-Drug
interactions, Electroanalysis, 14, 965-974.
5 Erdem, A., Özsöz, M. (2001) Voltammetry of the anticancer drug mitoxantrone and DNA, Turkish
Journal Chemistry, 25: 469- 475.
6 Palecek, E., Fojta, M., Jelen, F., Vetterl, V. (2002). Electrochemical analysis of nükleic asids, the
Encyclopedia of electrochemistry, Bioelectrochemistry,
9: 365-429.
Poster Presentation – PP0124
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A Highly Sensitive Nonenzymatic Ascorbic Acid Sensor Based on
Quantum Dots and Graphene Oxide
D. Söğüt1*, Z.Ö. Erdoğan1, C.Başlak1 and S. Küçükkolbaşı1
1Department of Chemistry, Faculty of Science, Selçuk University, 42075 Konya, Turkey
*Presenter: dsogut90@gmail.com
Abstract
Ascorbic acid (AA), water soluble vitamin, plays
important role in several life processes, such as antioxidant, nutritional factors. AA is commonly used
in food, beverages, pharmaceutical and cosmetic [1].
The detection of AA is important in food industry and
diagnostic application. Many methods have been used
for detection of AA, including spectroscopy, titrimetry,
enzymatic analysis, HPLC, electrophoresis and
electrochemical methods. Among these methods,
electrochemical method is very interesting because of
their high sensitivity, ease of monitoring, simplicity and
low cost [2].
Because of their unique chemical, physical and electronic properties, Quantum dots (QDs) and graphen
oxide (GO) are now extremely attractive and important
nanomaterials in analytical applications [3]. In this
work, CdTe QDs with the size of about 3 nm were
prepared and a novel electrochemical sensing platform
of ascorbic acid on CdTe/GO electrode was explored. In
this study, a novel, stable and sensitive non-enzymatic
AA sensor was constructed based on a glassy carbon
electrode (GC) modified with quantum dots supported
on graphene oxide (QDs -GO).
The electrochemical performance of the modified electrode for detection of AA was investigated by cyclic
voltammetry and amperometric measurements.
Electrochemical properties of different materials on the
electrode surface was characterized by cyclic
voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements in 0.10 M KCl
solution containing 50 mM Fe(CN)6 3−/4− as a redox
probe. The effect of pH, buffer concentration,
deposition potential, deposition time and scan rate were
investigated for modified electrode.
Compared to a bare GC the modified electrode
exhibited a rapid response to AA and the amperometric
signal showed a good linear correlation to AA
concentration in a broad range from 32.5-500 µM with a
correlation coefficient of R = 0.9991. Moreover, the
proposed sensor was applied to the determination of AA
in in fresh fruit juice samples. The satisfactory results
obtained indicated that the proposed sensor was
promising for the development of novel electrochemical
sensing for AA determination.
Figure 1. Amperometric response of
CdTe/GO/GCE.
References
[1] Liu, J.J., Chen, Z.T., Tang, D.S., Wang, Y.B.,
Kang, . L.T., Yao, J. N., Sensors and Actuators B,
212 (2015) 214-219.
[2] Liu, B., Luo, L., Ding, Y., Si, X., Wei, Y., Ouyang,
X., Xu, D., Electrochimica Acta, 142 8 (2014) 336-
342
[3] Zhao, J., Chen G., Zhu L., Li G., Electrochemistry
Communications, 13 (2011) 31–33.
Poster Presentation – PP0125
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Application of SWCNT and poly(3-methylthiophene) modified sensors for
simultaneous determination of levodopa and benserazide
Ebru Kuyumcu Savan
1* and Gamze Erdoğdu
2
1Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, İnönü University, Malatya, Turkey 2Department of Chemistry, Faculty of Science, İnönü University, Malatya, Turkey
*Presenter: ebru.kuyumcu@inonu.edu.tr
1. Introduction
Levedopa (L-Dopa) and Benserazide are a significant
neurotransmitters because of its role in the functioning
of the cardiovascular, renal and central nervous system.
It is important to detect L-Dopa and Benserazide using a
reliable method with good sensitivity and selectivity.
Due to the electrochemically oxidizable characteristic,
there has long been a great deal of developments in
electrochemical determination of L-Dopa and
Benserazide [1-3]. The coexistence of L-Dopa and
Benserazide and other reductants such as ascorbic acid with very close oxidation potentials leads to interference
in voltammetric response. The anodic potentials of AA,
L-Dopa and Benserazide at unmodified sensors always
overlap with each other, which is the major problem in
their simultaneous determination by electroanalytical
methods [4,5]. Therefore, improvement of the
sensitivity and selectivity of the sensor towards L-Dopa
and Benserazide has been a longstanding issue of
researchers. To overcome this problem, a glassy carbon
electrode was modified with electropolymerized film of
3-methylthiophene and single-walled carbon nanotube.
2. Experimental
Instrumentation
All the electrochemical operations (Cyclic voltammetry
(CV) and Differential pulse voltammetry (DPV) were
carried out by a BAS (Bioanalytical Systems, Inc.) 100
W electrochemical analyzer. The three electrode system
consisting of a glassy carbon disc working electrode
(geometric area: 6.85 mm2, CHI), an nonaqueous
Ag/Ag+ reference electrode (CHI112) and a Pt wire coil
auxiliary electrode (CHI) was used.
Preparation of modified sensor
Conducting polymer coating on the GCE was achieved in a three-electrode single-compartment cell containing
150 mM 3-methylthiophene (3-MT) and 100 mM
TBATFB (as electrolyte) dissolved in acetonitrile. The
polymer film was grown on GCE by CV from (-200) to
(+2000) mV at 50 mV/s for 14 cycle. N,N-
dimethylformamide (DMF) dispersions of the single-
walled carbon nanotubes (SWCNT) were prepared at
different concentrations, 0.2%, 0.5%, 1.0% (mg/μL).
Modified sensors while acquiring, 3-MT films, are
coated above and below of the SWCNT-COOH on the
GCE surface. For this purpose, different volumes (10,
20 µL) of SWCNT/DMF dispersions were added dropwise on poly (3-MT) film or bare GC electrode and
dried at room temperature for 1 day.
3. Results and Discussion
Determination of Levedopa and Benserazide
Figure 1. DPV results of 1.0 mM LD ve 1.0 mM BS on a)11.; b)12.;
c)13.; d)14.; e)15.; f)16. modified sensors
Interference study
Figure 2. DPVs for a mixture of 1.0 mM LD, 0.1 mM BS and 5.0 mM
AA at modified sensor in pH 7.0 PBS.
4. Conclusion
The modified sensor has been used for investigation of
the dermination of Levedopa and Benserazide in the presence of AA. The modified sensor has an excellent
response and specificity for the electrocatalytic
oxidation of Levedopa and Benserazide in PBS (pH
7.0). Linear calibration curves for DPV analysis were
obtained. By obtaining very low LOD, Levedopa
(1.77x10-5 M) and Benserazide (9.7x10-5 M) can be
determined simultaneously in the presence of interfence
such as AA.
References
[1] Anal. Chem. 73, (2001), 1196. [2] Anal. Chem. 71, (1999), 1055.
[3] J. Braz. Chem. Soc. 21(8), (2010), 1572.
[4] J. Electroanal. Chem. 561, (2004), 173.
[5] Anal. Chem. 68, (1996), 2084.
Poster Presentation – PP0128
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Simultaneous determination of levodopa and carbidopa in the presence of
ascorbic acid using nanostructured electrochemical sensor based on 3-
methylthiophene and MWCNT
Ebru Kuyumcu Savan1* and Gamze Erdoğdu2
1Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, İnönü University, Malatya, Turkey
2Department of Chemistry, Faculty of Science, İnönü University, Malatya, Turkey
*Presenter: ebru.kuyumcu@inonu.edu.tr
1. Introduction
Parkinson’s disease is believed to be related to low levels of the neurotransmitter dopamine in the brain. Therefore, the dopamine precursor levodopa is employed for its treatment. For better therapeutic effect and lower toxicity, carbidopa is administered in association with levodopa in pharmaceutical
formulation containing 10–25% of carbidopa [1]. For simultaneous determination of levodopa and carbidopa a glassy carbon electrode was modified with electropolymerized film of 3-methylthiophene (3-MT) and multi-walled carbon nanotube. Utilizing the developed method, determination of the two compounds has been carried out in pharmaceutical formulations, water and urine samples.
2. Experimental
All the electrochemical operations were carried out by a BAS
100 W electrochemical analyzer with three electrode system. Conducting polymer coating on the GCE was achieved containing 150 mM 3-MT and 100 mM TBATFB (as electrolyte) dissolved in acetonitrile by CV. Modified sensors while acquiring, poly(3-MT) films, are coated above and below of the MWCNT-COOH on the GCE surface.
3. Results and Discussion
Simultaneous determination ol LD and CD
Fig.1. DPV results of 1.0 mM LD ve 0.1 mM CD on a)1.; b)12.; c)13.;
d)14.; e)15.; f)16. modified sensors
Fig.2. DPVs for a mixture of 1.0-5.0 mM LD, 0.1 mM CD and 5.0 mM
AA at modified sensor in pH 7.0 PBS.
Fig.3. DPVs for a mixture of 1.0 mM LD, 0.1 mM CD and 5.0 mM AA
at modified sensor in pH 7.0 PBS.
Table 1. Electrochemical determination of LD and CD in Sinemet
tablet Tablet (mg) Found (mg) Recovery%
Sample LD CD LD CD LD CD
1 2.262 0.226 2.448 0.229 108.2 101.4
2 2.262 0.226 2.092 0.216 92.49 95.51
3 2.262 0.226 2.078 0.230 91.85 101.4
4 2.262 0.226 2.238 0.224 98.94 99.16
5 2.262 0.226 1.897 0.228 83.86 100.6
Mean 95.06 99.60
SD 8.12 2.20
RSD% 8.54 2.21
RE% 4.94 0.40
4. Conclusion
The modified sensor has an excellent response and specificity for the electrocatalytic oxidation of Levedopa and Carbidopa.
References
[1] Bioelectrochemistry. 93, (2013), 15–22.
Poster Presentation – PP0129
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
An investigation of the effect of 2,4-dithio-phenoxy-1-iodo-4-bromo benzene
molecule on rat liver and kidney tissue
Eda Çınar Avar1*, Elif Loğoğlu1 and Şule Coşkun Cevher2
1Gazi University, Faculty of Sciences, Department of Chemical, Ankara, Turkey 2Gazi University, Faculty of Sciences, Department of Biology, Ankara, Turkey
*Presenter: edaavar@gazi.edu.tr
1. Introduction
Nowadays fungal infections, tuberculosis, cancer and
AIDS have become the main cause and the most
important complexities of death and/or morbidity for the people who had an organ transplant and their immune
system depressed (1,2). Triazole antifungal compounds
like fluconazole and voriconazole function inhibiting
the lanosterol cytochrome P450 14α-demethylase
(CYP51) enzyme. However, clinical values, relatively
high toxicity, the emerge of drug resistance and
pharmacokinetic shortcomings of these compounds are
limited because of their lack of antifungal activities.
Broad spectrum antifungal agents with low toxicities are
still needed in despite of the recent developments (3,4).
In this sense the antifungal and antibacterial effects of
the newly synthesized thio halo-benzene derivative 2,4-dithio-phenoxy-1-iodo-4-bromo benzene have been
revealed in previous studies. This compound has similar
carbon structure with commonly used antifungal drug
fluconazole, not to mention that it is more active than
low concentrations of fluconazole.
2. Methods
In this study, effects of previously proved as an
antibacterial and antifungal molecule 2,4-dithio-
phenoxy-1-iodo-4-bromo benzene (C18H12S2IBr) on
mammal liver tissue and mammal kidney using
biochemical methods. 30 adult Wistar albino rats between the range of 150-200 gr have been used for this
study. Total 6 female rats have been used as subjects in
this experiment. Rats have been given fluconazole as
well as 2,4-dithio-phenoxy-1-iodo-4-bromo benzene
orally, each dissolved in alcohol, once in a week for 4
weeks. All subjects separated into 5 groups: a control
group, alcohol control, fluconazole group (0.28 mgr/100
gr) and two different doses of 2,4-dithio-phenoxy-1-
iodo-4-bromo benzene (0.112 mg/100 gr and 0.056
mg/100 gr).
3. Results and discussion
When 2,4-dithio-phenoxy-1-iodo-4-bromo benzene
molecule and fluconazole compared, it is shown that
2,4-dithio-phenoxy-1-iodo-4-bromo benzene does not
cause any oxidative damage on liver tissue particularly
on female rats, in fact it is even acts like an antioxidant
because of its low MDA levels (lower than control
group).
Table 1. Results from female rat liver MDA, GSH, AA,
NO levels and MPO activity
MDA
(nmol/g tissue)
GSH
(nmol/g tissue)
AA
(nmol/g tissue)
MPO
(nmol/g tissue)
NOX
(nmol/g tissue)
Group 1 122.8±28.8a
22.7±4.6a
3.5±0.2a
0.7±0.10a
436.7±18.2a
Group 2 135.3±17.3b
28.4±4.2b
- 0.7±0.08b
426.8±36.2b
Group 3 77.2±4.1c
19.3±1.6c
- 0.4±0.02c
477.7±16.7c
Group 4 57.5±4.5d
18.8±1.9d
2.9±0.2d
0.4±0.02d
450.2±9.4d
Group 5 48.6±7.7e
18.9±1.2e
2.7±0.4e
0.4±0.02e
426.3±15.0e
For MDA levels : a-c, a-d, a-e, b-c, b-d, b-e, c-e p< 0.05
For GSH levels : a-c, a-d, a-e, b-c, b-d, b-e p< 0.05
For AA levels: a-d, a-e p< 0.05
For MPO activity: a-c, a-d, a-e, b-c, b-d, b-e p< 0.05
For NOx levels: a-c, b-c, c-d, c-e , d-e p< 0.05
The effects of this two molecule -fluconazole and newly synthesized antifungal and antibacterial 2,4-
dithiophenoxy-1-iodo-4-bromo benzene on mammal
tissues examined on both male and female rat liver and
kidney tissues. This effects on mammal tissues
examined as liver and kidney MDA, GSH, AA, NO
levels and MPO activity. Liver MDA, GSH, NO, AA
levels and MPO activity of female rats have been given
in Table 1. These two new antioxidants considered to
be used to eliminate the free radicals in the chemical
metabolism when GSH and AA levels from all groups
are compared. Changes in MPO activity indicates that
2,4-dithio-phenoxy-1-iodo-4-bromo benzene molecule doesn’t contribute to neutrophil infiltration as well as
fluconazole. It is concluded that this newly synthesized
antifungal compound does not cause any oxidative
damage in kidney tissue, especially on males.
References
[1] S.K. Fridkin and W.R. Jarvis, Clin. Microbiol. Rev. 9 (1996), pp. 499–511.
[2] J.R. Wingard and H. Leather, Biol. Blood Marrow Transplant. 10 (2004), pp.
73–90.
[3] P. Kale and L.B. Johnson, Drugs Today 41 (2005), pp. 91–105.
[4] S. Sundriyal, R.K. Sharma and R. Jain, Curr. Med. Chem. 13 (2006), pp.
1321–1335.
Poster Presentation – PP0130
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
The Effect of the para and meta Positions in Immobilized New Supports
for Determination Phosmate
E. Hasanoğlu Özkan1*, N. Kurnaz Yetim1,2, N. Sarı1 and A. Dişli1
1 Department of Chemistry, Gazi University, Ankara, Turkey
2 Department of Chemistry, Kırklareli University, Kırklareli, Turkey
*Presenter: elvanelvan_06@hotmail.com
1. Introduction
As is known, enzyme is immobilization by interactions
between the support and the enzyme such as covalent
bonding, hydrogen bonding and Van Der Waals forces
[10]. If a polymer-based nano-sphere supports have
electronegative groups like Oxygen, nitrogen and
fluorine may be useful for increasing the enzyme
stability via hydrogen bonding attachment [11]. So, the
surface on which the enzyme is immobilized has several
vital roles to play such as retaining of tertiary structure
in the enzyme through hydrogen bonding. Acetylcholinesterase (AChE) is crucial enzyme in the
central nervous system of living organisms [12]. The
inhibition of AChE activity by organophosphorus (OP)
compound is an irreversible process. In this process,
AChE is inactivated. OP compounds, commonly used as
insecticides [13]. AChE is a serine protease enzyme.
The inhibition of AChE catalytic activity by OP is
caused due to phosphorylation of serine residue [14].
2. Experimental
a. Immobilization of AChE on nanomaterial
(2AEPS-(m/p-F-Tet-1H)
After dissolving enzyme in pure water (50 mL, 3.6 x 10-4 gL-1), 2AEPS-(m-F-Tet-1H) and (AEPS-(p-F-Tet-
1H) polymers (0.5 g) were placed to a 2 mL of 3.6 x 10-
4 gL-1 of AChE. This solution was diluted to 10 ml and
at room temperature in a shaking water bath for 8 h. The
immobilized polymers were separated and the free
enzyme was removed by washing with phosphate buffer
and then stored at + 4 °C. Saturation ratio was
determined as 97.60 % and 93.70 % for 2AEPS-(m-F-
Tet-1H) and 2AEPS-(p-F-Tet-1H) respectively, from
absorbance value in 412 nm.
b. Study on phosmate insecticide
N-(Mercaptomethyl) phthalimide S-(O,O-dimethyl
phosphorodithioate) was dissolved in Acetonitryl:H2O
(1.37 x 10-7 mol/L; 1:4, v/v) and its solutions were
prepared in between 10 μL - 50 μL. The absorbance
changes at 412 nm was taken into account for studied
phosmate solutions.
3. Conclusion
The first time has been presented in this study, ligated
new tetrazole derivatives on sphere have been
synthesized for the identification of organophosphates.
AChE immobilization has been successfully fabricated
for the detection of pesticide. Even for this reason, in
pesticide determination of 2AEPS-(p-F-Tet-1H)-AChE
and 2AEPS-(m-F-Tet-1H)-AChE have made more
easily interact with phosmet insecticide. The apparent
pesticide effect of the immobilized supports were
compared, and this showed that the 2AEPS-(p-F-Tet-
1H)-AChE was higher than 2AEPS-(m-F-Tet-1H)-
AChE. Probably, stereo chemical structure of 2AEPS-
(p-F-Tet-1H)-AChE has been protected the three-
dimensional structure of the enzyme by means of
hydrogen bonds.
Figure 1 Hydrogen bonds in between enzyme and
support material and photography related with
phosmet insecticide
References
[1] Beatriz M. Brena and Francisco, Batista-Viera,
Methods in Biotechnology: Immobilization of Enzymes
and Cells, Second Edition Edited by: J. M. Guisan ©
Humana Press Inc., Totowa, NJ.
[2] Hasanoğlu Özkan E, Kurnaz Yetim N, Tümtürk H,
Sarı N (2015) Dalton Trans 44: 16865-16872
[3] Periasamy AP, Umasankar Y, Chen SM (2009) A
Review,Sensors 9: 4034-4055
[4] Buckley NA, Roberts D, Eddleston M (2004) BMJ
329:1231
[5] Warner J, Andreescu S (2016) Talanta 146:79–284
Poster Presentation – PP0131
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
An ultra-sensitive PtNPs@Graphene/Nafion electrochemical sensing-platform
for detection of silodosin in human plasma
E. Er1*, H. Çelikkan
2 and N. Erk
1
1 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey
2 Department of Chemistry, Faculty of Science, Gazi University, Ankara, Turkey
*Presenter: eer@ankara.edu.tr
1. Introduction
The enlargement of the prostate gland is common in men with an increasing percentage at least 50% of men
aged over 50 years have histological evidence of benign
prostatic hyperplasia (BPH). Silodosin (SIL), α1-
adrenoreceptor antagonist in alpha-blockers class, is a
novel therapeutic agent for the treatment of the signs
and symptoms of BPH. It relieves the muscles of the
urinary bladder and prostate tract by selectively
affecting the symptoms of BPH. The recommended
dosage of SIL to relieve is 8 mg per day as it indicates
the best selectivity at this dosage [1–2]. Therefore, the
determination of SIL at low-level has a great importance especially in real samples [3]. In this point, we
proposed a novel electrochemical nano-platform based
on Platinum nanoparticles supported graphene/nafion
(PtNPs@GRP/NFN) nanocomposite material for the
electrochemical sensing of SIL using adsorptive
stripping differential pulse voltammetry (AdsDPV).
2. Experimental
Platinum nanoparticles/graphene (PtNPs@GRP) nanocomposite was produced from graphene oxide
(GO) via single-step reduction method (Figure 1) [4-5].
The formation of PtNPs@GRP was confirmed by x-ray
diffraction (XRD) and Transmission electron
microscopy (TEM).
Figure 1. Schematic presentation of the preparation
process of PtNPs@graphene nanocomposites
For the fabrication of proposed sensor, PtNPs@GRP
solution containing NFN (0.25%, v/v) was prepared to
constitute the PtNPs@GRP/NFN nanocomposite, and
followed by the modification of glassy carbon electrode
(GCE) surface with PtNPs@GRP/NFN nanocomposite.
A well-defined and irreversible oxidation peak at 714
mV was observed on the surface of PtNPs@GRP/NFN modified electrode using AdsDPV. Under optimized
conditions, PtNPs@GRP/NFN sensor exhibited an
excellent analytical performance in the detection of SIL
at nano-molar levels. The linear concentration range for
SIL was found to be 1.0-290 nM with a lower detection
limit at sub-nanomolar level.
3. Conclusion
Herein, we report a fabrication of new-generation
graphene-based electrochemical sensing platform for
the detection of SIL in human plasma. PtNPs@GRP
was effectively synthesized from GO and platinum salt using a single-step chemical reduction process.
PtNPs@GRP/NFN sensor exhibited an extraordinary
analytical performance owing to its owing to its unique
physical and chemical properties such as high surface
area, unique electrical conductivity, excellent
electrocatalytic and electrochemical activity. In
addition, proposed sensor enable to detect the SIL at
nano-molar level. It is concluded that
PtNPs@GRP/NFN sensor is a promising
electrochemical sensing-platform for the determination
of SIL in real samples.
References
[1] M. Yoshida, Y. Homma, K. Kawabe, Exp. Opin. on
Invest. Drugs 16 (2007) 1955.
[2] X. Zhao, Y. Liu, J. Xu, D. Zhang, et al., J.
Chromatogr. B 877 (2009) 3724.
[3] E. Er, H. Çelikkan, N. Erk, M.L. Aksu, Electrochim.
Acta 157 (2015) 252–257.
[4] W.S. Hummers, R.E. Offeman, J. Am. Chem. Soc.
80 (1958) 1339.
[5] T.Q. Xu, Q.L. Zhang, J.N. Zheng, et al.,
Electrochim. Acta 115(2014) 109–115.
Poster Presentation – PP0132
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Use of Bacterial Cellulose Membrane in the Removal of Azo Dyes
E.P. Çoban1*, U.C. Sağlam1, H. H. Biyik1
1 Department of Biology, Adnan Menderes University, Aydın, Turkey
*Presenter:epoyrazoglu@adu.edu.tr
1. Introduction
The use of dye materials is widely known in textile, plastic and paper industries [1]. The mixture of dye substances with natural water disrupts the ecological balance of water and its chemical content has a negative effect on living things. The preferred method of removing of dyes is the use of activated carbon. Although the method is effective, regeneration and reuse is a disadvantage due to cost and decrease in activity [2]. For this reason, Bacterial cellulose; a low-cost, easy to obtain and simple, with a fine reticulated pore structure and flexible
absorbent material, has been intended as an alternative. For this purpose, bacterial cellulose synthesized by Gluconacetobacter hansenii HE1 bacteria is being researched for its removal effects of Azo dye such as Aniline Blue, a widely used dye in textile.
2. Material and Method Material The Aniline Blue dye (CAS No. 66687-07-8, Sigma). Gluconacetobacter hansenii HE1 strain used in this study was provided from Adnan Menderes University Microbiology Laboratory stock cultures.
Production and purification of cellulose G. hansenii HE1 strain was inoculated in HS (Hestrin-
Schramm) (2% glucose, 0.5% yeast extract, 0.5% polypeptone, 0.675% Na2HPO4, 0.115% citric acid) broth and was allowed to produce cellulose after an incubation period of 10 days at 300C [3]. 4% NaOH and 6% acetic acid solutions were used for purification and dried by lyophilisation [4].
Dye removal Batch adsorption assay was carried out by shaking.50 mL of aniline blue solution was prepared at different concentrations (50,100 and 200 mg/L).1g of dried bacterial cellulose was added to the solutions and the solutions pH was set to a pH of 7 by using 1.0 N HCl and 1.0 N NaOH. It was kept on shaker
at 120 rpm at 280C. After, a period of 10 minutes and spectrophotometric readings were taken at 585 nm. In addition pH reading was made to observe pH changes. 50 mL of Aniline Blue (50 mg/L) was used as a positive control, 50 ml of distilled water containing cellulose was used as a negative control [1].
3. Results and Discussion Initial spectrophotometric measurements were found to be 0.3325 at 50 mg/L; 0.4116 at 100 mg/L and 1.4300 at 200 mg/L. While measurements made at 10 minute intervals showed a fading in colour, a spectrophotometric measurement
after 60 minutes were 0.0659; 0.1057 and 0.2026 respectively. Despite the solution`s starting pH of 7, as the colour fade the pH became alkaline. After 60 minutes pH observed were 8.9, 8.8, and 8.7 respectively. While the positive control containing Aniline blue solution had a pH of 8.7 and a spectrophotometric reading of 2.3868, negative containing bacterial cellulose and distilled water showed a spectrophotometric reading of 0.0336 and a pH of 7.2.
Figure 1 The initial image at different concentrations
of aniline blue dye
Table 1 Effect of bacterial cellulose on Aniline blue removal at 585 nm
Removal of dyes with bacteria cellulose at 200 mg/L solution yielded much better results than other concentrations. The results show that bacterial cellulose with a loose network, porous and nanofibril properties can be used in the removal of dyes.
Acknowledgements: This research was supported by supported TUBITAK BIDEP-2209. Project Number: 1919B011501637.
References [1] Pansar PS, Chavan YV, Bera MB, Chand O, Kumar H. Evaluation
of Acetobacter strain for the production of microbial cellulose. Asian J. Chem. 2009; 10:99–102.
[2] Bhavna VM, Satish VP. Bacterial cellulose of Gluconoacetobacter
hansenii as a potential bioadsorption agent for its green environment
applications. J. Biomat. Sci. 2014; 25(18):2053-2065.
[3]. Hestrin S, Schramm M. Synthesis of cellulose by Acetobacter
xylinum preparation of freeze dried cells capable of polymerizing
glucose to cellulose. Biochem J. 1954; 58(2):345-352.
[4]. Hyun JY, Mahanty B, Kim CG. Utilization of makgeolli sludge
filtrate (MSF) as low-cost substrate for bacterial cellulose production
by Gluconacetobacter xylinus. Appl Biochem Biotechnol.
2014;172(8):3748–60.
Figure 2 60 minutes after
the initial image at different
concentrations of aniline
blue dye
Poster Presentation – PP0133
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Vapor-Phase Deposition of Polymers Asa Simple and Versatile Technique to
Generate Paper-Based Microfluidic Platforms for Bioassay Applications
E. Babur1* and G. Demirel1
1 Department of Chemistry, Gazi University, Ankara, Turkey
*Presenter: esra.babur@gmail.com
1. Introduction
Paper-based sensor platforms having patterned fluidic
channels have a great potential in food, environment,
and health areas. Furthermore, paper-based materials
constitute suitable platforms in terms of easy
attainability and processability. Especially paper-based
sensor platforms’ replacing the conventional diagnostic
kits dependent on electronic gadgets can be estimated to
be popular considering both the cost and user-friendly
usage. However, certain difficulties have already being
seen on the issues of sample flow control, decreasing
the limit of detection, and repeatability in the paper-based sensor platforms. Especially various difficulties
have been encountered in the formation and application
of hydrophobic barriers on the hydrophilic paper to
provide a suitable flow [1,2]. In this study, we
demonstrate an alternative approach to fabricate paper-
based sensor platforms through a vapor-phase polymer
deposition technique. Furthermore, analysis of certain
target molecules such as glucose, protein, ALP, ALT and
uric acid are displayed using fabricated platforms.
2. Experimental
The conformal coating of poly(chloro-p-xylene) [PPX] films on paper samples (Whatman no. 1
chromatography paper) were performed using a SCS-
PDS2010 deposition system. A hydrophobic dichloro-
[2.2]-paracyclophane molecule was used in the
deposition process as a starting monomer. The polymer
deposition process was started by placing proper
amounts of monomer (0.01 g – 2.0 g) into evacuated
sublimator chamber. These monomers were then
evaporated at ~175 °C and converted to radicalic
monomers by pyrolysis (~695 °C). They were
subsequently deposited and polymerized onto paper samples. All process was carried out under vacuum
condition (32 mTorr). The corresponding PPX thickness
on paper samples was controlled through the amount of
the loaded monomer. The hydrophilic channels on paper
samples, which allow to transport the analyte solutions
via capillary penetration, were created using a metal
mask with desired pattern. The paper samples were
sandwiched between metal masks and magnets [3].
Figure 1 Schematic representation of the fabrication process of polymer deposition on a paper substrate
[inset: polymerization mechanism of PPX] (a),
sandwich array for patterning of the paper (b) and
colored water droplets on polymer deposited paper (c).
3. Results
We have demonstrated a technique for fabrication of paper-based sensor platforms through vapor phase
polymer deposition approach. The fabricated paper
platforms were successfully utilized for the detection of
varying biological target molecules including glucose,
protein, ALP, ALT, and uric acid. Given its
environmental friendly, solvent-free, and material
independent nature of vapor phase polymerization
method may offer new possibilities in the field of
biosensor applications.
Acknowledgements: This work was supported by the
TUBITAK (Grant 112T560) and Gazi University
(05/2015-19). Authors would like to thank Hakan Erdogan for useful discussions.
4. References
[1] E. Carrilho, A. W. Martinez and G. M. Whitesides,
Anal. Chem., 2009, 81, 7091–7095.
[2] A. W. Martinez, S. T. Phillips and G. M.
Whitesides, Anal. Chem., 2010, 82, 3–10.
[3] G. Demirel and E. Babur, Analyst, 2014, 139, 2326-
2331.
Poster Presentation – PP0134
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Sensing Studies of a Amine Functionalized Calixarene Derivative Coated QCM
Biosensor in Aqueous Solution
F. Temel1*, E. Ozcelik1, M. Akpinar1 and M. Tabakci1
1 Department of Chemical Engineering, Selçuk University, Konya, Turkey
*Presenter: farabitemel42@selcuk.edu.tr
Abstract
Biosensors are device which have properties of biological sensing to use for controlling and sensing of
biologic analytes. In biosensor applications, there are
several methods which are electrochemical,
calorimetric, optical and acoustic systems for
determination and sensing biologic analyte-biochemical
interaction [1].
Quartz Crystal Microbalance (QCM) is a sensor device which is simple, ease of use, low cost, shorter analysis
time for detection. During detection, mass accumulation
occurs on quartz surface and this causes frequency shift. QCM device can be used many application like antigen–
antibody, enzyme-substrate interaction, drug carrier,
volatile organic compounds detection [2]. Relationship
between frequency and mass change in liquid contact
measurement can be expressed Sauerbrey equation
2
02
Am f C f
f
(1)
where ∆m is mass change on sensor surface, ∆f is
frequency shift, ρ is density of quartz, µ is shear
modulus of quartz, A= active area of quartz and f0 is fundamental frequency of the of QCM crystal.
Calixarenes, are macrocyclic molecules which have unique three–dimensional structure and unlimited
derivatization potential. They can be synthesized by
condensation of p-tert-butylphenol with formaldehyde.
Calixarenes can be used for sensing applications [4].
Figure 2 Amine Functionalized Calix[4]arene
derivative
There are limited numbers studies about
macromolecules as biochemical sensors even though
there are many studies about polymeric materials. In
macromolecules, there are few studies about calixarenes
as biochemical material. Synthesis and derivatization of
calixarenes which can be easily detected desired
biological analyte and easily preparation of their films
on QCM crystals show that calixarenes can be used to detect biological analytes widely. In our previous
works, we have also synthesized some calixarene
compounds and they has been investigated their sensing
properties for volatile organic compounds. In this study,
we have prepared a calixarene derivative, its sensor
films and investigated its sensing abilities for bioanalyte
by calixarene-coated QCM system.
1. References
[1] Corcuera, J. I. R. D., Cavalieri, R. P., 2003
“Biosensor” , Encyclopedia of Agricultural, Food, and
Biological Engineering, 119 – 123.
[2] Lucklum, R., Hauptmann, P., 2006, “Acoustic
microsensors – the challenge behind microgravimetry”,
Anal. Bioanal. Chem., 384, 667 – 682.
[3] Sauerbrey, G., 1959, “The use of quartz oscillators for weighing thin layers and for micro-weighing”, Z.
Phys. 155, 206–222.
[4] Temel, F., Tabakci, M., 2016, “Calix[4]arene coated
QCM sensors for detection of VOC emissions:
Methylene chloride sensing studies”, Talanta, 153, 221
– 227.
Poster Presentation – PP0135
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Detection of Escherichia coli using Quartz Crystal Microbalance Sensor:
A Study Design
Mehmet Çağrı Soylu1, Fatma Betül Köşker1* and Keziban Canıkara1
1 Department of Biomedical Engineering, Erciyes University, Erciyes, Turkey
*Presenter: fbkosker@erciyes.edu.tr
1. Introduction
Escherichia coli (E. coli), a natural member of human
intestinal microbiota, is one of the leading
microorganism some strains of which is a cause of
foodborne or waterborne diseases via fecal
contamination [1].
In this study, rapid, simple and sensitive genetic
detection of non-pathogenic E. coli K-12 MG1655
strain has been aimed without the need of DNA
isolation, purification and amplification.
2. Materials and Method
All the probe oligonucleotides, reagents and E. coli K-
12 MG1655 strain (ATCC 47076) will be obtained
commercially and the bacteria will be cultured.
Phosphate buffered saline (PBS) will be used for
dilution. The ssDNA will be designed based on the
chosen conserved gene region (i.e. uidA gene). The
ssDNA probe will be modified at 5’ end with C6-SH. A
synthetic target DNA with complementary sequence of
probe DNA will be used for detection. The sensor
specificity will be determined using an oligonucleotide
with the same sequence of probe DNA.
The experimental design is shown in Figure 1 and the main stages of the detection procedure are:
I. Surface modification with 3-
Mercaptopropyltrimethoxysilane (MPS) for
electrical insulation [2],
II. Immobilization of the ssDNA probe,
III. Blocking with Bovine Serum Albumin (BSA) to
prevent adsorption on sensor surface,
IV. Extracting E. coli DNA with high temperature
(97 ºC) and detergent,
V. Driving the solution including target DNA via
peristaltic pump, VI. Analyzing the frequency change with impedance
analyzer,
VII. Examining the surface morphology via scanning
electron microscopy (SEM).
The stages are illustrated in Figure 2. Concentration of E. coli, the amount of BSA and detergent, flow rate,
immobilization, Signal-to-noise ratio (SNR) and signal
matching algorithm will be optimized during the
experiments.
Figure 1. Experimental design
SNR must be above 3. The target level of detection is
determined as 1010 copy/ml which is expected to be
increased using microspheres to 105 copy/ml.
3. Results
The designed and optimised system for non-
pathogenic E. coli will be used for detection of
pathogenic and toxigenic E. coli strains at the next
level.
References
[1] Lee, H., et al., Rate and molecular spectrum of
spontaneous mutations in the bacterium
Escherichia coli as determined by whole-genome
sequencing. Proceedings of the National
Academy of Sciences, 2012. 109(41): p. E2774-
E2783.
[2] Soylu, M.C., W.-H. Shih, and W.Y. Shih, Insulation by Solution 3-Mercaptopropyltrimethoxysilane
(MPS) Coating: Effect of pH, Water, and MPS
Content. Industrial & Engineering Chemistry
Research, 2013. 52(7): p. 2590-2597.
Figure 3. Study design and detection procedure
Poster Presentation – PP0136
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A new sensitive electrochemical method for simultaneous determination of
amlodipine and telmisartan drug
F. Kartal1*, N. K. Bakirhan1 and S. A. Ozkan1
1 Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara, Turkey
*Presenter: fatmakartal93@gmail.com
1. Introduction
Twynsta is used to treat high blood pressure
(hypertension). Lowering blood pressure may lower
your risk of a stroke or heart attack. Twynsta contains a
combination of amlodipine (AML) and telmisartan
(TLM). AML is a calcium channel blocker. AML
relaxes (widens) blood vessels and improves blood flow.
TLM is an angiotensin II receptor antagonist. TLM
keeps blood vessels from narrowing, which lowers
blood pressure and improves blood flow.
Up to date, AML and TLM compounds have been
studied with spectrophotometry, liquid chromatography.
However, there is no information about simultaneous
determination of these two compound with
electrochemical methods. And also, there is no
quantitative developed method has been proposed for its
analysis in dosage forms by electrochemical method.
2. Experimental
In this work the voltammetric behavior of AML and
TLM disodium was studied at a glassy carbon. The aim of this work is to carry out a detailed investigation on
the electrochemical behavior and possible oxidation
mechanism of AML and TLM disodium by using cyclic,
differential pulse, and square wave voltammetric
techniques. For this purpose, AML and TLM were
studied in various supporting electrolyte including
H2SO4, phosphate, acetate and Britton-Robinson buffers
(pH values between 0.3–10.0) containing 10%
methanol. The scan rate studies were realized in 0.5 M
H2SO4 solution for glassy carbon electrode,
understanding the mass transfer process to the electrode
surface. When the scan rate was varied from 5 to 750 mVs−1 in 1×10−4 M AML and TLM disodium solution, a
linear dependence (r≥0.999) of the peak intensity Ipa
(µA) upon the scan rate (mV.s−1) was found for a glassy carbon electrode, demonstrating an adsorption
process.
3. Results & Discussion
Voltammetric method exhibited linear dynamic
responses for simultaneous assay of AML and TLM in
the concentration range between 1.0×10-7 M – 1×10-4 M
and 1.0×10-7
M – 1.0×10-5
M, with detection limits of
0.654 nM and 22.6 nM, respectively.
AML
Figure 1. TLM
4. Conclusion
Simple, selective, sensitive, fully validated, rapid, and reliable adsorptive stripping square wave voltammetry
methods were applied for the simultaneous analysis of
AML and TLM in pharmaceutical dosage form,
Twynsta. Precision and accuracy of developed method
was checked by recovery studies. These techniques did
not require sample pre-treatment or any time-consuming
extraction step prior to drug assay in dosage forms.
Poster Presentation – PP0137
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A novel electroanalytical nanosensor based on AgNPs nanoparticles for
determination of antiviral drug tenofovir
G. Ozcelikay1*, B. Dogan-Topal1 and S.A. Ozkan1
1Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, 06100 Ankara, Turkey
*Presenter: ozcelikayg@ankara.edu.tr
1. Introduction
Tenofovir Disoproksil Fumarat (TEN) is an antiviral
drug active compound which is used for the treatment of
the AIDS. The voltammetric oxidation of TEN was
investigated at silver nanoparticles modified glassy
carbon electrode using cyclic (CV), Osteryoung Square
Wave Stripping (OSWSV) Voltammetry over a wide
pH range.
For the analytical application, operational parameters
have been optimized. The dependence of intensities of
currents and potential on pH, concentration, scan rate,
nature of the buffer was investigated.
2. Methods
a. Reagents and Apparatus
A stock solution of 1.0x10-3 M was prepared by
dissolving the compound in bidistilled water. Standard
solutions were prepared by serial dilution of the stock
solution with selected supporting electrolyte.
The CV and OSWSV experiments were performed
using a BAS 100W electrochemical analyzer. The
utilized electrodes were: silver nanoparticles modified
glassy carbon as a working electrode; a platinum wire as
a counter electrode and an Ag/AgCl (BAS; 3M KCl) as a reference electrode.
OSWSV conditions: pulse amplitude, 35 mV;
frequency, 30 Hz; potential step 8 mV. The parameters
of stripping methods were also optimized.
AgNP amount was investigated for the well-defined
peak shape and peak current. 5.0–15.0 µL AgNP
suspensions were dropped on GCE surface. The
optimum result was obtained with 10.0 µL AgNP
suspensions in pH 5.7 acetate buffer.
b. Analysis of tablets
A weighed portion of the powder content equivalent to
1x10-3M of tenofovir was transferred into a 50mL-calibrated flask and completed to the volume with
bidistilled water.
3. Results and Discussion
No previous electrochemical studies were available the
sensitive anodic electroanalytical determination of TEN
in its dosage forms.
The results revealed that the oxidation of TEN is an
irreversible pH-dependent process in an adsorption-
controlled mechanism. The calibration curve was linear
in the concentration range of 8x10-8-1x10-6M with a
detection limit of 4,30x10-9M.
Figure 1. OSWSV of 4x10-6 M TEN at bare electrode
(blue line) and AgNps modified carbon electrode (red
line).
The OSWSV method was successfully applied for the
analysis of TEN from pharmaceutical dosage forms. No
electroactive interferences from the tablet excipients.
4. Conclusion
In the present work, the electrochemical behavior of
TEN was investigated by CV and OSWSV. In these
investigations, the effect of the pH of the buffer solution
and potential sweep rate were described. This study demonstrated that modification of GCE with AgNPs
was a new and sensitive application for the
electrochemical determination of TEN [1]. The method
was validated in accordance with ICH guidelines and
the obtained results were within acceptable criteria.
References
[1] N. Karadas, B. Bozal-Palabiyik, B. Uslu, S.A.
Ozkan, Functionalized carbon nanotubes—With
silver nanoparticles to fabricate a sensor for the
determination of zolmitriptan in its dosage forms
and biological samples, Sensors and Actuators B
186 (2013) 486–494
i p(µA)
Ep (mV)
Poster Presentation – PP0140
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Heteroarylboronic Acid Loaded Nanostructures:
Synthesis of 5-Pyrimidylboronic acid
G. Taskor1* and N.Saygili1
1 Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
*Presenter: gulcet@hacettepe.edu.tr
1. Introduction
The objective of this work was to formulate a
nanostructured possible biosensor with ability to choose
the diols. Boronic acids bind covalently with 1, 2- or 1,
3-diols to generate five or sixmembered cyclic
complexes. 5-Pyrimidylboronic acid has been
synthesised by lithium-halogen exchange reactions on
5-bromopyrimidine, followed by reaction with
triisopropylborate (Scheme 1). 5-Pyrimidylboronic acid
was formulated as nanostructured lipid carriers (NLCs)
and characterized for size, zeta potential and
morphology.
2. Materials and Methods
Procedure for the Preparation of 5-
Pyrimidylboronic acid [1]: To a solution of 5-
bromopyrimidine (5.50 g, 34 mmol) and
triisopropylborate (13.0 g, 69 mmol) in anhydrous THF
(70 mL) at -78oC was added n-BuLi (1.6 M in hexane,
22.0 mL, 35 mmol) dropwise. The reaction mixture was
stirred for 4 h at -78oC then quenched with H2O (10
mL) and allowed to warm to 20oC with stirring
overnight. The solvent was evaporated in vacuo and the
aqueous layer was taken to pH 10 with 5% NaOH and was then washed with diethyl ether. The aqueous layer
was then acidified to pH 4 with 48% aq HBr to
precipitate 5-pyrimidylboronic acid as a white solid
(1.90 g, 45%).
Scheme 1. Synthesis of 5-Pyrimidylboronic Acid
Procedure for Preparation of Nanostructures [2]: A
prewarmed oil phase (1 mL) consisting of fish oil and
125 mg of 5-pyrimidylboronic acid dissolved in ethanol
was gradually added to the prewarmed aqueous phase (4
mL) containing 120 mg of egg phosphatidylcholine
(Lipoid E80), 10 mg of polysorbate 80 (Tween 80), and
10 mg of stearylamine. The resultant mixture was
stirred for 2 min using a homogenizer at 6000 rpm and
ultrasonicated for 10 min using a probe sonicator at
22%amplitude and 50% duty cycle.
Figure 1. Tem image of nanostructure (scale bar = 200
nm)
3. Results
Characterization of 5-Pyrimidylboronic Acid: Mp
>320oC; 1H NMR (DMSO-d6) δ 9.36 (s, 1 H), 9.17 (s, 2
H), 8.81 (s, 2 H, OH); 13C NMR (DMSO-d6) δ 161.84,
159.31. Anal. calc. for C4H5BN2O2·0.5H2O: C, 36.15;
H, 4.55; N, 21.08. Found: C, 36.47; H, 4.50, N, 20.80%.
5-Pyrimidylboronic acid loaded nanoemulsions
formulated for the development of novel boronic acid-based biosensors.
4. Conclusion
This work support the way for further studies on
synthesis of pyrimidylboronic acids and regulation of
their nanostructures. Boronic acid-based nanoemulsion
sensors would be useful alternatives for the sensitive
and selective detection of biomolecules which have
diols.
References
[1] Saygili N., Batsanov A. S., Bryce M. R. Org.
Biomol. Chem., 2004, 2, 852-857. [2] Yadav S., Gattacceca F., Panicucci R., Amiji M. M.
Mol. Pharmaceutics, 2015, 12, 1523-1533.
Poster Presentation – PP0142
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Development of electrochemical biosensor based on graphene–chitosan
composite for sensitive detection of vinclozoline
G. Bolat1*, O. Surucu1 and S.Abaci1
1Hacettepe University, Department of Chemistry, 06532 Ankara, Turkey
*Presenter: gbolat@hacettepe.edu.tr
Abstract
Pesticides are substances that are used to increase the
agricultural production by preventing the crop losses
from insects, herbicides or fungi. As a result of wide use
of pesticides in agrochemistry, there is a possibility to
run-off these toxic compounds into natural water bodies
and soil.
Vinclozoline, (VZ), 3-(3,5-dichlorophenyl)-5-methyl-5-
vinyl-1,3-oxazolidine-2,4-dione (Figure 1), is a
dicarboximide type of non-systemic fungicide that is
widely used for the control of several species of fungi in
vines (such as grapes), strawberries, vegetables and fruit
by inhibiting spore germination [1]. However, VZ, has
toxicity and functions as potential endocrine disruptor
that produces malformations in humans [2]. Also, the
low-solubility of fungicides in water may lead to serious environmental problems [3].
Considerable effort is being made to design sensitive
analytical methods for the detection of pesticides. The
mechanisms of reactions of dicarboximides and their
electrochemical behavior are still not known in detail.
The fabrication of electrochemical sensors based on
modified electrodes on the analytical determination of
pesticides has great amount of importance due to the excellent sensing properties [4]. Therefore, it is
important to discover appropriate electrode materials
to improve the performance for the pesticides sensing
[5]. Graphene films can be used as electrode materials
with electrocatalytic properties in their partially reduced
form. Graphene nanosheet (GN), in a honeycomb two-
dimensional (2D) sheet form, is a two-dimensional
carbon material which possesses novel properties, such
as large surface-to-volume ratio, well biocompatibility,
well mechanical properties and high electrical
conductivity. Graphene-based materials and nanocomposites show obvious superiorities on sensing
applications [6]. It has been reported that GR
nanosheets could be electrodeposited onto electrodes
through electrochemical reduction of graphene oxide
(GO) solution. Chitosan (CS) is a linear hydrophilic
nontoxic natural biopolymer that exhibits excellent
film-forming ability. Also, CS has been applied to
disperse nanomaterials. The GR–CS composite has been
shown as a suitable electrode material for pesticide
sensing, by facilitating the enrichment of pesticides on
the surface and improving the sensitivity [7].
To the best of our knowledge, there is no report on the
determination of VZ by using graphene-based
nanocomposite to VZ sensor. In this study, chitosan-
graphene matrix was used to fabricate the electrochemical sensor to determine the VZ.
Modification of the electrode surface and the
application for the detection of VZ was carried out
successfully. The high surface area of the composite
greatly increased the surface loading of VZ as sorbent
material.
Figure 1 Structure of vinclozolin.
1. References
[1] W.R. Kelce, E. Monosson, L.E. Gray, Recent
Progress in Hormone Research 50 (1995) 449–453. [2] S. Mc Gary, P.F.P. Henry, M.A. Ottinger,
Environmental Toxicology and Chemistry 20
(2001) 2487–2493.
[3] O. Belafdal, M. Bergon, J.P. Calmon, Pesticide
Science 17 (1986) 335–342.
[4] C.M.A. Brett, Pure Appl. Chem. 73 (2001) 1969–
1977.
[5] J.D. Fowler, J.M. Allen, V.C. Tung, Y. Yang, B.H.
Weiller, ACS Nano 3 (2009) 301–306.
[6] S. Stankovich, D.A. Dikin, G.H.B. Dommett,
K.M. Kohlhaas, E.J. Zimney, E.A. Stach, R.D. Piner, S.T. Nguyen, R.S. Ruoff, Nature 442
(2006) 282-286.
[7] T. Ramanathan, A.A. Abdala, S. Stankovich,D.A.
Dikin, M. Herrera-Alonso, R.D. Piner, Nat.
Nanotechnol. 3 (2008) 327-331.
Poster Presentation – PP0143
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Polydopamine Coated - SiNWs Target Surfaces for the Detection of Small
Molecules in Laser Desorption/Ionization Mass Spectrometry
G. Şanlı1*, G. Demirel2 and Ö. Çelikbıçak1
1 Department of Chemistry, Hacettepe University, Turkey,
2 Department of Chemistry, Gazi University, Turkey
*Presenter: g.sanli89@gmail.com
1.Introduction
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a surface-based technique that has been widely employed for the analysis/detection of biomolecules. In this method, the choice of the suitable matrix and the sample/matrix mixing ratio, the methods of the sample preparation and the way of sample introduction upon MALDI plate can cause different consequences in mass spectral
results. Apart from that, the excess amount of matrix molecules makes difficult the analysis of the small analyte
molecules which can be observed under 1000 m/z in mass
spectra.[1] To overcome these problems, reusable solid surfaces were produced by polydopamine (PDOP) coating on silicone nanowires (SiNWs) and these surfaces were used as a laser desorption/ ionization (LDI) target in this study. In order to test the effects of PDOP thickness on laser desorption/ionization (LDI) process, the SiNWs were coated with PDOP layer with different thicknesses by manipulating
PDOP deposition time (3h, 6h, 24h). Fabricated surfaces were then characterized by various techniques such as XPS (X-ray photoelectron spectroscopy), SEM (Scanning electron microscopy) and ellipsometry. Finally, performances of fabricated surfaces as a LDI target were tested and evaluated using some model drug and peptide molecules, such as; acrivastine, angiotensin II and substance P in MALDI-TOF-MS studies.
2.Materials and method
The vertical aligned silicon nanowires were fabricated through well-established metal-assisted chemical etching technique. [2]
Within this context, p-type silicon wafers were first cleaned consecutive sonication in ethanol, acetone, and deionized water for 10 min. The wafers were then immersed into a H2O2
and H2SO4 mixture having a volume ratio of 1:3 at 70°C for 60 min in order to remove metal and organic residues from silicon wafer surfaces. Afterwards, the silicon wafers were transferred into HF solution for 1 min and subsequently immersed into a PTFE baker containing 4.6 M of HF and 0.02 M of AgNO3 (1:1, v/v) for 1 min. The samples were finally immersed into a mixture of HF and H2O2 (10:1, v/v) at 25°C for 10-120 min. Afterwards, the wafers having desired
nanowire lengths were removed and washed with deionized (DI) water and nitric acid to remove by-products. To deposit PDOP on SiNWs, the fabricated SiNW arrays were first immersed into a dopamine solution (pH=8.5, 2 mg/mL) for varying time intervals (3-24 h). The samples were then removed and cleaned with DI water and dried with N2 gas.
3. Results and Discussion
Polydopamine coated SiNWs was employed as a LDI target and some model compounds having different molecular structures such as; acrivastine (348,4 Da), angiotensin II (1046,1 Da) and substance P (1347,6 Da) were applied onto
these surfaces as sample. In these studies, different target surfaces, produced by different polydopamine coating periods (3h, 6h and 24h) were also utilized to investigate effects of polydopamine layer thickness on LDI-MS analysis (Figure 1). [M+H+] signal of the acrivastin drug molecule was successfully observed by using polydopamine coated surfaces prepared by 3h and 6h time periods. However, LDI-MS signal
of acrivastine was disappeared on 24h polydopamine coated SiNWs. In the case of angiotensin II and substance P studies, it was observed that signal intensities of both polypeptides were increasing by growing thickness of polydopamine layer on SiNWs. These results represent that thin polydopamine layer on SiNWs are affective for detecting small molecules, while thicker polydomamine coatings are successful for relatively higher molecular weight compounds such as small polypeptides.
Figure 1: Acrivastine, angiotensin II and substance P analysis
on different PDOP coated surfaces. (A) acrivastin on 6h-PDOP. (B) Angiotensin II on 6h-PDOP (C) Substance P on 6h-PDOP. (D) acrivastin on 24h-PDOP. (E) Angiotensin II on 24h-PDOP. (F) Substance P on 24h-PDOP.
References
[1] Çelikbıçak, Ö., Demirel, G., Pişkin, E., Salih, B., Small Molecule Analysis Using Laser Desorption/Ionization Mass Spectrometry on Nano-Coated Silicon with Self-Assembled Monolayers. Analytica Chimica Acta, 2012, 729, 54-61. [2] Li, X.; Bohn, P., Metal-Assisted Chemical Etching in HF/H2O2 Produces Porous Silicon. Applied Physics Letters 2000, 77 (16), 2572-2574.
10 408 806 1204 1602 2000 m/z
[M+H]+
*
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K+
m/z10 208 406 604 802 1000
[2M+H
]+[M+H]+
F
F
F
F
FK+ F*
10 508 1006 1504 2002 2500 m/z
[M+H
]+
F*
**
***
***
*
K+
A
B
C
10 208 406 604 802 1000 m/z
10 408 806 1204 1602 2000 m/z
[M+H]+
*
K+
***
Na+
10 508 1006 1504 2002 2500 m/z
[M+H]+
*
K+
**Na+
D
E
F
Poster Presentation – PP0141
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Molecular Identification of Aspergillus and Penicilium Species with ITS-PCR
H. Halil Bıyık1, Bahadır Törün1, Yusuf Geroğlu1, Esin Poyrazoğlu Çoban1, Gamze Başbülbül1
1 Department of Biology University of Adnan Menderes,
*Presenter: hbiyik@adu.edu.tr
1. Introduction
Difficulties and confusions about identificatrion of fungi
with tradiotinal methods have turned researches to
molecular methods [1]. ITS is one of the polymorphic
DNA sequences between fungal species, nowadays it is
seen as a good candidate in terms of determining fungi species correctly and with this application they can be
deperated to a large extend. Aspergillus and Penicillium
have both positive and negative effects on human
aktivities, and widely distributed species. Some of the
species of this genus can be pathogenic while some of
them have industriel importance [2]. In this study
Aspergillus and Penicillium species in our stocks were
identified with molecular methods and long term
storage is provided.
2. Materials and Methods
In study, Aspergillus and Penicilium species which previously isolated and identified with morphological
methods and recorded at ADÜ Biology Department
stocks were used. DNA isolations of the samples were
made according to Tran-Dinh et al., (1999) [3]. DNA
concentration and purity control of the samples were
made with Nanodrop Spectrophotometer (Thermo).
Universal ITS 1 and ITS 4 primers were used for
molecular identification. PCR products were sent to
Macrogen (Holland) company for sequencing and
matched using BLASTn software.
3. Results and Discussion
One hundered twenty samples were matched with
GenBank using BLASTn software (GenBank;
http://ncbi.nlm.nih.gov) and 20 of the samples were
Aspergillus fumigatus, 12 of them were A.awamori, 9
of them A.niger, 6 of them A.tubingensis, 9 of them
A.terreus, 4 of them A.japonicus, 5 of them A.oryzae,
2 of them A.tamarii, 5 of them Penicilium commune, 6
of them P.chrysegeum, 2 of them Fusarium sp., 3 of
them Mucor circinelloides, 2 of them Lichtheimia
corymbifera, 1 of each Aspergillus versicolor,
A.brassiliensis, A.flavus, Penicillium griseofulyum, P. restrictum, Fusarium proliferatum, F. chlamydosporum,
Trichoderma saturnisporum, T. atroviride, T.
harzinarum, Alternaria promicola, Purpurecilium
lilacinum, Cladosporium cladosporioides, Eurotium
cristatum and Cytospora sp. were found (Table 1).
Mycelia and spores of Aspergillus and Penicillium were
lyophilizied and cathologed.
Classical parameters which used for identification of
microfungi includes; microscopic morphology,
physiological tests, cultural and clinical properties. But
uncertanity of phenotipic chracters makes harder to
identify species with morphological methods. Therefore
molecular approaches became an alternative method for identification of fungi. Lyophilisation and liquid drying
is difficult techniques for preserving fungi mycels and
spores. These techniques are especially used for
stocking and preserving mycels and spores over 20
years.
Table 1 Name of species and number of samples
identified
4. Acknowledgements
This research was supported by supported Adnan Menderes
University Research Fund. Project Number: ADU-BAP-FEF–10003.
References
[5] Edman JC, Kovacs JA, Masur H, Santi DV, Elwood HJ, Sogin
ML (1986) Ribosomal RNA sequence shows Pneumocystis
carinii to be a member of the fungi. Nature 334:519–522.
[6] Logrieco A, Peterson SW, Wicklow DT (1990) Ribosomal
RNA comparisons among taxa of the terverticillate penicillia.
In: Samson RA, Pitt JI (eds) Modern concepts in Penicillium
and Aspergillus classification. Plenum, New York, pp 343–356.
[7] Tran-Dinh, N., Pitt J.I., Carter D.A. 1999. Molecular genotype
analysis of natural toxigenic and nontoxigenic isolate of
Aspergillus flavus and A. parasiticus. Mycological Research,
103, 1485 –1490.
Poster Presentation – PP0144
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Zinc-Nickel nanostructures coated f-MWCNT nanocomposite electrode for
nonenzymatic glucose biosensing
Fatih Şen1, Yağmur Koşkun1, Hakan Sert1*, Gaye Başkaya1 and Aysun Savk1
1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupınar University, Kütahya,
Turkey
*Presenter: fatih.sen@dpu.edu.tr
Abstract
Mesoporous ZnO-NiO architectures were prepared by
thermal annealing of zinc-nickel hydroxycarbonate
composites [1]. The resulting architectures are shown to
be assembled by many mesoporous nanosheets, and this
results in a large surface area and a strong synergy
between the ZnO and NiO nanoparticles [2]. The obtained material was used as an electrode that responds
to glucose over a wide concentration range (from 0.5
μM to 6.4 mM), with a detection limit as low as 0.5 μM,
fast response time (<3s), and good sensitivity (120.5
μA·mM−1·cm−2) [3].
Figure 1. Cyclic voltammograms of the
GC/MWNT/NiO in the presence of 0.01 M
glucose at varying scan rates: (a) 10, (b) 20,
(c) 40, (d) 60, (e) 80, (f) 100, (g) 150 and
(h)200 mV s−1, respectively
References
[1] Liu, Q., Lu, X.B., Li, J., Yao, X., Li, J.H., (2007),
Biosens. Bioelectron. 22; 3203–3209. [2] Zeng, Q., Cheng, J.S., Liu, X.F., Bai, H.T., Jiang,
J.H., (2011), Biosens. Bioelectron. 26; 3456–3463.
[3] Ding, Y., Wang, Y., Su, L., Bellagamba, M., Zhang,
H., Lei, Y., (2010), Biosens. Bioelectron. 26; 542–548.
Poster Presentation – PP0147
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Surface Plasmon Resonance Imaging (SPRi) on a Smartphone for Point-of-care
Applications Hasan Guner1*, Erol Ozgur1, Guzin Kokturk2, Mehmet Celik3, Elif Esen2, Ahmet E. Topal1, Sencer Ayas4,
Yildiz Uludag2, Caglar Elbuken1 and Aykutlu Dana1
1UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey 2 UEKAE-BILGEM, TUBITAK, Gebze/Kocaeli, 41470, Turkey
3 Department of Computer Engineering, Middle East Technical University, Ankara, 06800, Turkey 4 Department of Radiology, Stanford School of Medicine, Palo Alto, CA 94304, USA
*Presenter: hguner@bilkent.edu.tr
1. Introduction
We demonstrate an on-chip plasmonic imaging platform integrated with a smartphone to be used in the field with high-throughput biodetection. Inexpensive and disposable SPR substrates are produced by metal coating of commercial Blu-ray discs [1,2]. Real-time bulk refractive index change measurements yield noise equivalent refractive index changes as low as 4.12 x 10-5 RIU which is comparable with the
detection performance of commercial instruments. We have shown capture of mouse IgG antibodies by immobilized layer of rabbit anti-mouse (RAM) IgG antibody with nanomolar level limit of detection. Our approach in miniaturization of SPR biosensing in a cost-effective manner could enable realization of portable SPR measurement systems and kits for point-of-care applications.
2. Materials and Methods
We designed a compact optical system, using a 3D-printed apparatus that hosts the LED source, collimator, bandpass filter, linear polarizer, beamsplitter plate and an external
imaging lens which can be easily attached to the smartphone (Figure 1). We employed a silver-gold bilayer structure coated on the periodic corrugations of Blu-ray discs in order to perform plasmon resonance imaging at the central region of
r~500 nm) under normal incidence illumination in aqueous environment (Figure 2). This allowed the optimal use of the CMOS sensor of the smartphone while maintaining high sensitivity, chemical stability and biological
affinity. A microfluidic channel is placed on the bi-metallic layer for controlled plumbing of the liquids. The use of Blu-ray discs and standard metal deposition techniques together with the low-cost microfluidic channel resulted in significant cost-reduction which can allow the system to be used for applications requiring disposable SPR biosensors.
Figure 1. Surface plasmon resonance imaging platform integrated with a smartphone
Figure 2. Grating coupled SPRi sensor chip
3. Results
SPR chip immobilized with RAM IgG is taken out the spectral interrogation setup (Figure 3a) and plugged into the smartphone attachment. Mouse IgG solutions at concentrations ranging from 1.33 nM to 830 nM were injected successively. Intensity changes of individual pixels at three distinct locations on the sensor surface is shown in Figure 3b. Dose-response curve reveals that nanomolar level detection of
antibody analyte is achievable within a dynamic range from a few nanomolars to micromolar concentration.
Figure 3 Nanomolar level detection of capture of mouse IgG
by immobilized layer of RAM IgG. (a) Spectral sensorgram showing the immobilization steps of RAM IgG. (b) Dose-response curve for the capture of mouse IgG.
References
[1] B. Turker, H. Guner et al. Lab Chip 11, 282 (2011) [2] B. Kaplan, H. Guner et al. Plasmonics 4, 237 (2009)
Poster Presentation – PP0148
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
The Synthesis and Characterization of PEI Modified Fe3O4/Au Nanoparticles
for Rapid Enumeration of E. coli
Hasan İlhan1*, Üzeyir Doğan2, Hakan Çiftçi3, Uğur Tamer2 and Necdet Sağlam1
1Department of Nanotechnology and Nanomedicine, Hacettepe University, Ankara, 06800, Turkey 2Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Ankara, 06330, Turkey
3Department of Chemistry and Chemical Processing Technologies, Kirikkale Vocational High School, Kirikkale
University, Kirikkale, 71450, Turkey
*Presenter: hasanilhan@hacettepe.edu.tr
1. Abstract:
Magnetic nanoparticles have been utilized as a powerful tool in various bioassays and used as solid support
owing to its advantages such as biocompatibility,
stability and immunomagnetic seperation. Modification
of these nanoparticles enable to straightforward
conjugation with bacteria or biomolecules of interest
[1,2]. Numerous magnetic nanoparticles have been
developed as magnetic carriers or separation and
purification process [3]. Polyethyleneimine (PEI) is a
water soluble cationic polymer consisting of amino and
imino groups which are expected to adsorb onto the
surface of gold coated magnetic nanoparticles [4]. Fe3O4/Au-PEI nanoparticles were synthesized in
aqueous solution and characterized by transmission
electron microscopy (TEM), UV-Vis
spectrophotometer, zeta potential and particle size
distribution.
2. Materials and Methods:
In this study, we report the preparation of magnetic
nanoparticle and modification of this nanoparticle specific to E.coli. This modified magnetic nanoparticle
provides immunomagnetic separation and specific
detection of the target bacteria. Enzyme substrate is
covalently linked between magnetic particle and target
bacteria to cleave bond easily using an enzyme. Then,
magnetic nanoparticle is cleaved from E. coli in order
not to prevent bacteria movement on the test strip. β-
casein is a good substrate for this application and yeast
enzyme is used for bond cleavage. The amide bonds of
β-casein on the magnetic particle-casein-biotin are
cleaved by the enzyme to release some or all of the biotin moieties from magnetic particle [5]. The
magnetic particles are removed by a magnet, and the
target bacteria in the solution can be detected efficiently
on the test strips. The target bacterium is also labeled
with horseradish peroxidase enzyme to enable
colorimetric detection on the test strip. Detection pad is
spotted with E. coli antibody, 3,3’,5,5’-
tetramethylbenzidine (TMB) and hydrogen peroxide
solutions to catch labelled bacteria and observe colored
product, respectively [6]. Colorimetric measurements
are taken on this spot with a portable CCD camera to
construct a calibration curve which enables quantitative analysis.
3. Conclusion
We believe that this new immunomagnetic sensing platform can be used in many application areas
including food quality, water contamination, clinical
diagnosis and environmental monitoring due to its
attractive advantages such as simple, low-cost, portable
and disposable features.
4. References:
[1] U. Tamer, A. Onay, H. Ciftci, and J. M. Greneche, J.Nanopart Res 16, 2624, (2014)
[2] U. Tamer, D. Cetin, Z. Suludere, I. H. Boyaci, and
Y. Elerman, Int. J. Mol. Sci.14, 6223, (2013)
[3] C. Wang, J. Xu, J. Wang, Z. Rong, P. Li, R. Xiao, S. Wang, J. Mater. Chem. C, 3, 8684, (2015)
[4] H. Ciftci, E. Alver, F. Celik, A. U. Metin, U. Tamer,
Microchim acta 183, 1479, (2016)
[5] W. Ren, I-H. Cho, Z. Zhou, and J. Irudayaraj, Chemcom 52, 4930, (2016)
[6] D. Kwon, S. Lee, M. M. Ahn and S. Jeon, Analytica
Chimica Acta, 883, 61, (2015)
Poster Presentation – PP0149
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Detection of Listeria Monocytogenes Using Anisotropic Magnetic Nanoparticle
Based Surface Enhanced Raman Spectroscopy
Hande Yeğenoğlu1, Hilal Torul2*, Adem Zengin3, Belma Aslım1, Demet Çetin4, Zekiye Suludere1, İsmail Hakkı
Boyacı5,6, and Uğur Tamer2
1Department of Biology, Faculty of Art and Science, Gazi University 06500, Ankara, Turkey 2Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Etiler, Ankara 06330, Turkey
3Department of Chemical Engineering, Yüzüncü Yıl University, Van 65080, Turkey 4Science Teaching Programme, Gazi Faculty of Education, Gazi University, Besevler, Ankara 06500, Turkey
5Department of Food Engineering, Hacettepe University, Beytepe, Ankara 06800, Turkey 6Food Research Center, Hacettepe University, 06800 Beytepe, Ankara, Turkey
*Presenter: hilaltrl@gmail.com
1. Introduction
Diseases caused by bacterial pathogens are intense
concerns due to occurrence of high death rate in the world [1]. For this reason, detection of bacterial
pathogens in food products has an importance. Although there are several detection methods developed
for this purpose, these conventional methods usually
include microbiological culturing and plating, which are
time-consuming due to consist of several enrichment
steps. In addition to conventional methods, some
different techniques including flow cytometry [2],
enzyme-linked immunosorbent assay (ELISA) [3], and
polymerase chain reaction (PCR) [4] have been
developed. Nevertheless, these techniques have some limitations such as sensitivity, specificity, speed, and
cost efficiency. As a result of these limitations,
development of a new method is significantly necessary
to detect low concentrations of pathogens in different
media [5]. In this work, a highly selective and sensitive
SERS system was developed for immunomagnetic
separation and detection of Listeria monocytogenes in
milk sample.
2. Experimental
Anisotropic magnetic gold nanoparticles with SERS
active properties were synthesized and used in
immunoassay systems. In order to collect L. Monocytogenes bacteria from milk sample, bacteria
were interacted with novel antibody conjugated
magnetic Fe-Au nanoparticles. Then the collected
bacteria were interacted with DTNB labeled gold
nanoparticles to measure amount of Listeria
monocytogenes in milk sample.
3. Result
The calibration curve was obtained with the changes of
the peak intensities of NO2 stretching band versus
different L. monocytogenes bacteria concentrations.
Figure 1. The decrease of the peak intensity at 1333 cm-
1 illustrated symmetric NO2 stretching bands of DTNB
at increasing L. monocytogenes concentrations
obtained with magnetic gold nanoparticles; a) no
Listeria monocytogenes , b) 2,2 x 101 cfu/mL, c) 2,2 x
102 cfu/mL, d) 2,2 x 103 cfu/mL, e) 2,2 x 104 cfu/mL, f)
2,2 x 105 cfu/mL, g) 2,2 x 106 cfu/mL
The SERS response was found to be linear between the
concentration of bacteria in range 2,2x101-106 cfu/mL. (R2: 0.991).
References
[1] Yang L. and Bashir R., Biotechnology Advances,
2008, 26, 135–150.
[2] Kempf V.A.J., Mandle T., Schumacher U., Schafer
A. and Autenrieth I. B., Int. J. Med. Microbiol., 2005,
295, 47−55.
[3] Dylla B.L., Vetter E.A., Hughes J.G., and Cockerill
F.R., J. Clin. Microbiol., 1995, 33, 222−224.
[4] Belgrader P., Benett W., Hadley D., Richards J.,
Stratton P., Mariella R. and Milanovich F., Science, 1999, 284, 449−450.
[5] Zhou H., Yang D., Ivleva N.P., Mircescu N.E. and
Niessner R., Anal. Chem., 2014, 86, 1525−1533.
Poster Presentation – PP0150
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Synthesis of DNA Aptamer Conjugated Magnetic Graphene Oxide and Its Use
As A Photo-thermal Agent for Killing Methicillin-Resistant Staphylococcus
Aureus
Ismail Ocsoy1*
and Muserref Arslan Ocsoy2
1Department of Analytical Chemistry, Faculty of Pharmacy, Erciyes University, 38039 Kayseri, Turkey
2Department of Physics, Faculty of Science, Erciyes University, 38039 Kayseri, Turkey;
*Presenter: ismailocsoy@erciyes.edu.tr
The detection and destruction of bacteria is not only important for human and animal health but also for
industry and crop production security. Staphylococcus
aureus (SA) which is the one of the most dangerous
disease-causing bacteria exhibits the resistance to
various antibiotics. The methicillin resistant
staphylococcus aureus (MRSA) is one of the most
dangerous pathogenic (disease-causing) bacteria is
usually called “superbug”8-10. It The has been high
demand to develope alternative and effective
approaches rather than using antibiotics in order to
efficiently detect or destruct the MRSA.
In this study, a multifunctional nano platform was
developed for detection and photothermally destruction
of MRSA bacteria. Magnetic GO functionalized with
MRSA aptamers was produced for this purpose. First of
all, the iron oxide (Fe3O4) nanoparticles (NPs) were
grown on the surface of the GO and magnetic GO
(mGO) was functionalized the aptamers modified with
amin (-NH2) group on one end that were specifically
synthesized for MRSA. The MRSA bacteria were
rapidly, sensitively and accurately captured with
aptamer functionalized mGO (Apt@mGO) and it was photothermally destroyed under the near infrared laser
(NIR, 808 nm). While aptamer specifically binds to
MRSA, MRSA were magnetically separated with a
magnet without centrifugation due to Fe3O4 NPs on the
surface of the GO. While GO is used as a platform for
aptamer and Fe3O4 NPs, it is utilized a photothermal
agent converting laser light to heat when exposed to 808
nm NIR laser. Also, it is considered that GO tightly
wraps the MRSA bacteria due its sheet shape and
carrying several functional groups on the surface.
Figure 1. Illustration of the binding of Apt@mGO to MRSA and cell destruction throught PTT
Figure 2. Illustration of the suspension and aggregation
Apt@mGO-MRSA bacteria.
References
[1] Lancet. Infect. Dis. 2010, 10, 597–602.
[2] Arch Intern Med.1998, 158, 895–899.
[3] Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 11838–
11843.
[4] ACS Nano, 2013, 7, 8972-8980.
[5] RSC Adv. 2016, 6, 30285-30292.
[6] ACS Nano, 2013, 7 (2), pp 1281–1290
Poster Presentation – PP0146
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
The Investigation of DNA Binding Profiles of Gold Nanoparticle Bound Lignan
Species Called Lariciresinol Using Spectrophotometry and Spectrofluorimetry
İsmail Murat Palabıyık1*, Nuri Özmen
1, Mehmet Gökhan Çağlayan
1 and Feyyaz Onur
1
1Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, Ankara,Turkey
*Presenter: mpala@pharmacy.ankara.edu.tr
1. Introduction
Owing to both the life style and environmental
problems; nowadays frequency of prevalence of cancer
diseases highly increased so far as the past years.
Lignans, also called phytoestrogens, are one of the main
groups of herbal components. In recent years, in vitro,
animal and some epidemiological studies have reported the possibility of lignans to be used in treatment of
prostate, breast and colon cancers via antiestrogenic,
antiangiogenic, antioxidant and proapoptotic
mechanism [1,2].
2. Scope
Within the scope of studies of this study, connection of
lignan species namely lariciresinol to gold nanoparticles
modified by β-cyclodextrine were achieved and
interactions of pure and connected form of lariciresinol
with single and double strand DNA were established
using with spectrophotometric and spectrofluorimetric methods.
3. Results and Conclusion
In this study, interaction between pure and bounded
form of lariciresinol and double strand DNA were
investigated in different pH, ionic strength and
temperature. In spectrums obtained from
spectrophotometry, there is an increase in absorbances,
batochromic shift in bounded form (Figure 1) and
hypsochromic shift in pure form. Beside this, an
isosbestic point was observed and binding constant was
changed in different ionic strength. In spectrofluorimetric measurements, a quenching (Figure
2) was observed with increasing in DNA concentrations.
Also, Ksv values are decreased with increasing in
temperature (except 313 K). These findings are shown
that there is a binding between DNA and lariciresinol
and this binding is occurred both intercalation and
groove binding way [3].
Figure 1. Observed spectrums of LARI - β-CD-AuNP
with increasing concentrations in dsDNA 0.1 M
Na2HPO4 (pH: 7.40)
Figure 2. Observed florescence spectrums of
LARI - β-CD-AuNP with increasing in dsDNA
concentrations in 0.1 M Na2HPO4 (pH: 7.40)
Table 1. Ksv values for interactions between LARI - β-CD-AuNP and dsDNA in different experimental medium
Experimental conditions Ksv values
pH 4.40 0.01 M
NaH2PO4
1350.50
pH 7.40 0.01 M
Na2HPO4
1101.40
pH 8.40 0.01 M
Na2HPO4
831.32
0.05 M NaCl 1130.60
0.10 M NaCl 1068.20
0.20 M NaCl 1078.60
298 K 969.06
303 K 1278.60
308 K 1522.50
313 K 1282.70
Acknowledgements: This study was supported by The
Scientific and Technological Research Council of
Turkey, Grant SBAG-112S591
References
[1] Chen, J., Thompson, L.U. Breast Cancer Research and
Treatment, 80, 163–70, 2003.
[2] Chen, L.H., Fang, J., Sun, Z., Li, H., Wu, Y., Demark-
Wahnefried, W., Lin, X. Journal of Nutrition, 139, 653-9, 2009.
[3] Sirajuddin, M., Ali, S., Badshah, A. Journal of Photochemistry and Photobiology B Biology, 124, 1 – 19, 2015.
600 650 700 750 8000
100
200
300
400
Wavelength (nm)
Inte
nsity (
a.u
.)
Poster Presentation – PP0152
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A Novel Hydrogel System for the Wound Healing in the Diabetic Patients
K. A. Usal1,2* and T. Dursun3,4
1 Department of Cognitive Science, Middle East Technical University
2 Department of Research and Development, İleri Biyotek Biomedical R&D Company, 3 Department of Biotechnology, Middle East Technical University
4 Department of Biological Sciences, Middle East Technical University
*Presenter: e199523@metumail.edu.tr
1. Introduction
Wound healing is a specific biological process related to
the general phenomenon of growth and tissue
regeneration [1]. It includes a series of interdependent and overlapping stages in which a variety of cellular and
matrix components act together to reestablish the
integrity of damaged tissue and replacement of lost
tissue [2]. Diabetic patients have severe problems in the wound healing process due to the damaged blood flow
to the required areas [3]. Therefore, any minor scar can
turn into ulcers in the extremities, especially feet. If
these scars are not treated, these problematic wounds
would cause amputation. Nowadays, general wound
cleaning procedures are applied to treat the patients,
however, these treatments are not enough to provide a
complete healing.
Hydrogels contain significant amounts of water (70-
90%) and possess most of the desirable characteristics
of an ‘ideal dressing’ [4]. Experimental studies in animals have demonstrated that the topical application
of epidermal growth factor accelerates the rate of epidermal regeneration of partial-thickness wounds and
second-degree burns [5]. In this study, a hydrogel loaded with epidermal growth factor (EGF) will be
produced to improve the healing process in the diabetic
patients. This hydrogel system can also be used in any
type of wound to provide a faster and improved healing
process.
2. Materials and Method
Hydrogel was composed of methacrylated gelatin.
Therefore, methacrylation of gelatin was done. gelatin
was dissolved in water and methacrylic anhydride (3%,
v/v) was added dropwise, and the reaction run for 2 h at
50˚C. The solution was dialyzed against distilled water. Methacrylated gelatin (GELMA) obtained was dried
with lyophilisation and stored at 4˚C. Crosslinking of GELMA hydrogel was achieved with UV exposure (at
365 nm) (Figure 1).
3. Results and Discussion
Characterization studies showed that these GELMA
hydrogels have appropriate pore size (100 (µm) and porosity (75%) for the cell attachment and the
proliferation studies. Water content of the GELMA
hydrogels was found as 95% (w/w). Therefore, it can be
classified as high water content hydrogel and its
biocompatibility is expected to be high.
After the characterization studies, in vitro performances
of the EGF-loaded GELMA hydrogels will be
performed. At the end, a growth factor loaded hydrogel
system will be produced for the use of diabetic patient’s wounds.
Figure 1 Synthesis of methacrylated gelatin. Gelatin
macromers containing primary amine groups were reacted
with methacrylic anhydride (MA) to add methacrylate pendant
groups (A). To create a hydrogel network, the methacrylated
gelatin was crosslinked using UV irradiation in the presence
of a photoinitiator (B) Taken from Khademhosseini et al.,
2010 [6].
References
[1] Boateng, J. S., Matthews, K. H., Stevens, H. N., &
Eccleston, G. M. (2008). Wound healing dressings and drug delivery systems: a review. Journal of pharmaceutical sciences, 97(8), 2892-2923.
[2] Rothe M, Falanga V. 1989. Growth factors, their biology and promise in dermatologic disease and tissue repair. Arch Dermatol125: 1390–1398.
[3] Moura, L. I., Dias, A. M., Carvalho, E., & de Sousa, H. C. (2013). Recent advances on the development of wound
dressings for diabetic foot ulcer treatment-A review. Acta biomaterialia, 9(7), 7093-7114.
[4] Morgan DA. 1999. Wound management products in the drug tariff. Pharm J 263:820–825.
[5] Brown, G. L., Nanney, L. B., Griffen, J., Cramer, A. B.,
Yancey, J. M., Curtsinger III, L. J., ... & Lynch, J. B. (1989). Enhancement of wound healing by topical treatment with epidermal growth factor. New England Journal of Medicine, 321(2), 76-79.
[6] Nichol, J. W., Koshy, S. T., Bae, H., Hwang, C. M., Yamanlar, S., & Khademhosseini, A. (2010). Cell-laden microengineered gelatin methacrylate hydrogels. Biomaterials, 31(21), 5536-5544.
Poster Presentation – PP0154
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Adsorptive stripping determination of Ezetimibe in pharmaceutical dosage
forms and biological fluids
L. Karadurmus1,2*, S. Kurbanoglu2, B. Uslu2 and S.A. Ozkan2
1 Adıyaman University, Faculty of Pharmacy, Department of Analytical Chemistry, Adıyaman Turkey
2 Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, Turkey
*Presenter: leylakrdrms@gmail.com
1. Introduction
Electroanalytical methods emerge with the interplay
between electricity and chemistry; in other words they
were used to measure electrical quantities, such as
current, potential, or charge and their relationship with
the chemical parameters. These methods are widely
used in fields like environmental monitoring, industrial
quality control or biomedical analysis [1]. Another field
in which electrochemical methods are extensively used
is drug analysis and these methods have proved to be
highly sensitive due to the straight forwardness, low cost and relatively short analysis time [2].
Glassy carbon electrode (GCE) is the most common
carbon-based electrode because of its excellent
mechanical and electrical properties, wide potential
range, chemically inert nature and impermeability to
gases. They are easily mounted, polishable and
compatible with all common solvents. They allow many
applications in many different areas, since their
performances are relatively reproducible. Ezetimibe
((3R,4S)-1-(4-fluorophenyl)-3-[(3S)-3- (4-fluorophenyl)
-3-hydroxyl propyl)] -4-(4-hydroxy phenyl)-2-azetidinone) is a drug that inhibits cholesterol
absorption from the small intestine, which was
approved by the US Food and Drug Administration for
the treatment of primary hypercholesterolemia [3,4].
2. Experimental
Voltammetric measurements were recorded using BAS
100 W (Bioanalytical System, USA), electrochemical
analyzer with a standard three-electrode configuration.
The three electrode system consisted of a GCE (BAS: Ф
= 3 mm, diameter) as working electrode, a platinum
wire counter electrode, and an Ag/AgCl saturated KCl reference electrode. GCE was polished manually with
aqueous slurry of alumina powder (Ф = 0.01 μm) on a
damp smooth polishing cloth (BAS velvet polishing
pad) just before each measurement. All measurements
were achieved at room temperature.
In this study, the electrochemical behavior of Ezetimibe
was investigated using adsorptive stripping differential
pulse voltammetric method.
3. Results
The electrochemical behavior of Ezetimibe was
investigated with in a wide pH range (pH 0.3-7.0) using
adsorptive stripping differential pulse voltammetric technique at glassy carbon electrode. With adsorptive
stripping differential pulse voltammetric technique,
maximum current was observed in the pH 0.3 sulfuric
acid medium. As a result of scan rate studies, in the pH
0.3 sulfuric acid medium, the electrochemical behavior
of ezetimibe was found adsorption-controlled. From the
relation between Ep and logarithm of scan rate,
Ep=Eo+(2.303.RT/ά.n.F)logv n was calculated as 2.38.
Since ά is accepted as 0.5 for irreversible systems. The
peak potential was shifted to more negative values with
increasing pH. From the slope of the equation Log (Ip) =
0.78 log v – 1.19 (r=0.998) it can be resulted that the
reaction is adsorption controlled since the slope is close to 1. The Ep–pH equation of ezetimibe; Ep=998.49-
50.99 pH indicates that equal numbers of protons and
electrons are involved in the electrode reaction at GCE.
Under optimized deposition time and potential
conditions using adsorptive stripping differential pulse
voltammetric technique Ezetimibe was determined
concentration from 1x10-6 M to 2.5x10-5 M with a limit
of detection as 0.32 nM and limit of quantification as 1
nM. In optimized conditions, Ezetimibe determination
was achieved in human urine, and human serum. For the
validation of the proposed methods, precision and accuracy were examined by assaying five replicate
samples as individual days (within day) and
intermediate precision (between days). Relative
standard deviations (RSD %) and bias % were
calculated to check the precision of the method. After
statistical evaluation the results indicate that method is
analytically acceptable from the view point of precision
[5].
References
[1] J. Wang, “Analytical Electrochemistry”, Wiley-Vch,
New Jersey, 2006. [2] S.A. Ozkan, “Electroanalytical methods in
pharmaceutical analysis and their validation”, HNB
Pub., New York, 2011.
[3] L. L. Brunton, “Goodman and Gilman’s: The
pharmacological basis of therapeutics”, McGraw Hill
Press, New York, 2010.
[4] S. C. Sweetman, “Martindale: The Extra
Pharmacopoeia”, 35th edition. Pharmaceutical Press,
London, 2007.
[5] J. Ermer and J. H. Miller, “Method Validation in
Pharmaceutical Analysis”, Wiley-VCH, Weinheim,
2005.
Poster Presentation – PP0155
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A Paper-based Platform for Optical Sensing of Dopamine by Graphene
Quantum Dots
M. Esad Sağlam1*, Aylin Arıcı1, Ilker Akin2, Erhan Zor3 and Haluk Bingol4
1 Institute of Science, Necmettin Erbakan University, Konya, Turkey
2 Department of Chemistry, Selçuk University, Konya, Turkey 3 Department of Science Education, Necmettin Erbakan University, Konya, Turkey
4 Department of Chemistry Education, Necmettin Erbakan University, Konya, Turkey
*Presenter: muhammedesadsaglam@gmail.com
Abstract
Dopamine (DA) given in Figure 1 is one of the most
influential neurotransmitter in mammalian central
nervous system. Thus, its detection is very crucial for
the diagnoses, monitoring and treatments of several
neurological disorders such as Schizophrenia and
Parkinson’s disease. Different analytical methods have
been reported for DA determination, such as
chromatography combined with mass spectrometry,
optical and electrochemical techniques [1]. Although the methods can reach very low detection limits, the
procedures require not only sample pretreatment,
lengthy analysis times and high costs.
Figure 1 Structure of DA
In the recent years, many researchers have focused on
optical and electrochemical paper-based sensors which
are a new alternative technology for fabricating simple,
low-cost, portable and disposable analytical devices [2]. In fabricating paper-based sensors, the choice of
materials that meet the criteria of simplicity and
efficient production process need to be considered.
There are different optical materials involving simple
organic molecules, nanoparticle and quantum dots that
could be used to tune the optical and sensing properties
of the paper-based sensor. Graphene quantum dots
(GQDs), as a class of fluorescent probes, have attracted
considerable attention in recent years. Compared with
metal based quantum dots, GQDs have high photo-
stability, low toxicity, simple synthesis ways as well as tunable fluorescence emission properties, which gained
them increased attention in a variety of applications [3].
Herein, we report a novel, low cost, disposable, rapid
and straightforward paper-based platform embedded
photoluminescent GQDs for optical sensing of DA in
aqueous media. GQDs was prepared by top-down
synthesis based on acidic oxidation cutting of graphene
oxide (GO) following the literature [4]: GO firstly
synthesized using the improved Hummers method was
re-oxidized in HNO3 for 20 h at 90˚C. The mixture was
further dialyzed in a dialysis bag (MWCO: 2 kDa). The
GQDs were characterized by FT-IR, Raman, XPS and TEM. The water-soluble fluorescent GQDs is
transferred onto a commercial paper for “yes/no” type
optical sensing of DA by spotting and then dried to
remove the solvent. The orange emitting GQDs exhibit
excitation independent PL behavior. On excitation of the
absorption band of 470 nm, the PL spectrum of GQDs
exhibits a highest peak at 580 nm with a Stokes shift of
110 nm as can be seen in Figure 2. The fluorescence
intensity of the GQDs in aqueous media turned out to
decrease sensitively when interacted with DA molecules
(the inset of Fig. 3). It displayed the fluorescence
change as a function of the concentration of DA from
6.0 µM to 120.0 µM in harmony with the literature [5].
The charge transfer between GQDs and DA molecules linked by hydrogen bonding and electrostatic interaction
was suggested to be responsible for the fluorescence
quenching of the GQDs.
Figure 2 The fluorescence excitation and emission spectra of
the GQDs dispersed in water
Figure 3 The fluorescence sensing of DA by commercial paper embedded GQDs.
Figure 3 demonstrates the fluorogenic detection of DA
using GQDs on the commercial paper. Once the paper-
based sensor was fabricated, the DA solution was
dropped onto the loading zone. The PL quenching showed the presence of DA in aqueous media.
Acknowledgement: The authors are grateful to the Scientific Research Projects of Necmettin Erbakan University (161310004) for financial support.
References [1] Polo, E. and Kruss S. Anal Bioanal Chem. 408 (2016), 2727-41.
[2] Liana D.D. et al., Sensors, 24 (2012), 11505-26.
[3] Zheng X.T. et al., Small, 11 (2015), 1620–1636. [4] Fan L. et al., Talanta, 101 (2012), 192–197.
[5] Zhao et al., Sensors & Actuators, B: Chemical, 223 (2016), 246-251.
Poster Presentation – PP0201
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electropolymerized Films of 1,3-Bis(2-pyridylimino)isoindolato-palladium
Complex: Biosensor Applications
Metin Ak1, Tuğba Soğancı1, Tuğçe Yazıcı Tekbaşoğlu2, Atıf Koca3 and M. Kasım Şener2*
1 Department of Chemistry, Pamukkale University, 20017 Denizli, Turkey
2 Department of Chemistry, Yıldız Technical University, 34210 İstanbul, Turkey 3 Department of Chemical Engineering, Marmara University, 34722 İstanbul, Turkey
*Presenter: mkasimsener@gmail.com
1. Introduction
The chemistry of isoindolines has been the key for the
development of phthalocyanines as well as related
macrocycles and chelating ligands [1]. Among the
isoindoline-based chelating ligands, bis(2-
pyridylimino)isoindolines (BPI) have been the focus of
interest because they are readily synthesized and easily
modified. [2]. Most of the published papers about bis(2-
pyridylimino)isoindolines and their metal complexes
focused on structural characterization and main application areas of these compounds are homogeneous
catalysis and biomimetics [3]. Here, we present first
time a new bis(2-pyridylimino)isoindolato-palladium
complex bearing electropolymerizable EDOT (3,4-
(ethylenedioxy)thiophene) substituent and show it may
be used for glucose sensing as heterogeneous catalytic
system.
2. Experimental
Monomer palladium complex EDOT-PdBPI was
synthesized from EDOT-BPI [4] (Figure 1).
Polymerization of synthesized monomer and
copolymerization with HKCN [5] were carried out by an electrochemical method. In addition to all of these, a
simply fabricated amperometric glucose sensor based on
glucose oxidase (GOx), P(EDOT-PdBPI-co-HKCN)
modified graphite rod electrode was improved.
O O
S
O
NN N
N NPd
Cl
NS S
NHO
NH2
EDOT-PdBPI HKCN
O O
S
O
HNN N
N N
EDOT-BPI
Figure 1. Structural formulas of monomers
3. Results and Discussion
In our matrix, amino groups which are arising from the
HKCN were used for the enzyme immobilization. On
the other hand, the presence of EDOT-PdBPI serves an
extra electron by reason of the oxidation of H2O2 to O2. Amperometric detection was carried out following
oxygen consumption at -0.7 V vs. the Ag reference
electrode in phosphate buffer (50 mM, pH 6.0). The
proposed sensor showed a linear amperometric response
for glucose within a concentration range of 0.25 mM to
2.5 mM (LOD: 0.176 mM). Amperometric signals at 1
mM of glucose were 17.9 μA under anaerobic
conditions. Amperometric signals of the P(EDOT-
PdBPI-co-HKCN)/GOx electrode decreased by 13%
within eight week. The P(EDOT-PdBPI-co-
HKCN)/GOx electrode showed excellent selectivity in
the presence of ethanol and phenol. This result shows
that, modification of the proposed sensor by glucose oxidase led to the fabrication of a glucose biosensor
with excellent performance (Figure 2).
Figure 2. Amperometric biosensor response of
P(HKCN)/GOx, P(EDOT-PdBPI)/GOx,
P(EDOT-PdBPI-co-HKCN)/GOx
Acknowledgments: This work was supported by
TÜBİTAK (Project Number: 115Z555).
References
[1] I-S. Tamgho, J. T. Engle, C. J. Ziegler, Tetrahedron Lett., 2013,
54, 6114-6117.
[2] M. K. Şener, U. Avcıata, J. Chem. Research, 2007, 3, 138-140.
[3] R. Csonka, G. Speier, J. Kaizer, RSC Adv., 2015, 5, 18401-18419.
[4] M. K. Şener, T. Yazıcı, A. Koca, 18. JCF-Frühjahrssymposium, Book of Posters, 2016, 222.
[5] H. C. Söyleyici, M. Ak, Y. Şahin, D. O. Demirkol, S. Timur, Mater. Chem. Phys., 2013, 142, 303-310.
Poster Presentation – PP0202
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Graphene/nafion nanocomposite based electrochemical biosensor for detecting
Hypoxanthine
M.Kurtulgu
1,2* and S.Çete
3
1Institue of Natural Sciences, University of Gazi/ 2Department of Basic Science, Turkish Military Academy
3Department of Chemistry, Gazi University, Ankara, Turkey
*Presenter: mkurtulgu@kho.edu.tr
1. Introduction
Graphene (GR), emerging as a true two-dimensional material, has received increasing attention due to its
unique physicochemical properties such as high surface
area (2630 m2g-1), excellent conductivity (200.000
cm2V-1s-1 for single layer), high mechanical strength,
and ease of functionalization and mass production. [1]
Xanthine mainly act to oppose the actions of the
sleepiness-inducing adenosine, and increase alertness in
the central nervous system. They also stimulate the
respiratory center, and are used for treatment of infantile
apnea. Due to widespread effects, the therapeutic range
of xanthine’s is narrow, making them merely a second-line asthma treatment. Also increasing the amount of
xanthine in tissue increases the risk of heart attack. [2]
The therapeutic level is 10-20 micrograms/mL blood;
signs of toxicity include tremor, nausea, nervousness,
and tachycardia/ arrhythmia. Also hypoxanthine is an
critical metabolite of adenine nucleotide degradation,
which is mainly accumulated in biological tissues .[3]
The level of hypoxanthine is used in the food industry
for evaluating the freshness of fish. So, the
determination of hypoxanthine has considerable
importance for quality control of fish and other
products in the food industry.[4]
2. Experimental Details
The synthesis of graphene from graphite was performed
according to the method of Hummer with some
modifications. [5] GR/PtNPs was synthesized from graphene oxide using single-step reduction method with
some modifications. [6] The quantification of xanthine
can be achieved via electrochemical detection of the
enzymatically released H2O2. The immobilization of
xanthine oxidase (XO) has been achieved by cross-
linking with glutaraldehyde. The performances of the
biosensor have been investigated by electrochemical
method at an optimum potential of +0.6 V in pH 8.0
phosphate buffer. All the electrochemical measurements
were performed with a conventional three-electrode
system.
3. Conclusion
There are many reports regarding the electro catalytic
activity of graphene based sensors for the applications
of H2O2. Some of them are listed in Table1. In our study
xanthine biosensor based on immobilization of XO in Pt
nanoparticles/ graphene/ nafion nanocomposite film is responsive to a low concentration of H2O2 (~5µM) and
two different linear determination ranges of 10-5
-10-4
M
and 10-3-10-1 M with R2= 0,999 and R2= 0,967
respectively. According to literature our sensor has low
detection limit and long linear range among to other
studies with good R2 values. This property shows us our
sensor is good candidates for biosensor applications.
Table–1 Comparison of the performance of H2O2 sensor
Potential (V)
Linear range Limit of detection
Ref.
−0.3 100 μM to 100 mM 31.3 μM [7]
−0.3 0.10–50 mM 4 μM [8]
−0.05 20 μM to 0.2 mM 1.9 μM [9]
−0.4 20 μM to 6.25 mM 2.5 μM [10]
−0.4 20 μM to 2.1 mM 9.4 μM [11]
+0.6
I.10 μM to 100 μM
II.1 mM to 100 mM
5 μM This
work
References
[1] Yuyan Shao, Jun Wang, Hong Wu, Jun Liu, Ilhan A. Aksay, Yuehe Lin,
Electroanalysis 2010, 22, No. 10, 1027 – 1036
[2] Bhagavan N.V, Xanthine oxidase reaction Medical Biochemistry,652-
654,1990.
[3] Zhang , J. ; Lei , J. ; Pan , R. ; Xue , Y. ; Ju , H. Biosens. Bioelectron. 2010 ,
26 , 371 .
[4] Hernandez-Cazares , A. S. ; Aristoy , M. C. ; Toldra , F. Food Chem. 2010 ,
123 , 949 .
[5] W.S.Hummers, R.E.Offeman, Preperation of graphitic oxide,
J.am.Chem.Soc.80 (1958) 1339
[6] G. Zhiguo, Y. Shuping, L. Zaijun, S. Xiulan, W. Guangli, F. Yinjun, L.
Junkang. Chim. Acta, 701 (2011), p. 75
[7] S. Liu, J.Q. Tian, L. Wang, X.P. Sun. Carbon, 49 (2011), p. 3158
[8] R. Ning, W.B. Lua, Y.W. Zhang, X.Y. Qin, Y.L. Luo, J.M. Hu, A.M. Asiri,
A.O. Al-Youbi, X.P. Sun Electrochimica Acta, 60 (2012)
[9] E. Jin, X.F. Lu, L.L. Cui, D.M. Chao, C. Wang Electrochimica Acta, 55
(2010), p. 7230
[10] X.X. Liu, H. Zhu, X.R. Yang Talanta, 87 (2011), p. 243
[11] S. Woo, Y.R. Kim, T.D. Chung, Y. Piao, H. Kim Electrochimica Acta, 59
(2012), p. 509
Poster Presentation – PP0203
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Layer-by-layer Films of Polydopamine and Gold Nanoparticles
G. Bakirci Dündar1, M. Yilmaz1,2* and Gokhan Demirel1
1Bio-inspired Materials Research Laboratory (BIMREL), Department of Chemistry, Gazi University 2 Department of Bioengineering, Sinop University
*Presenter:
Introduction
Many practical applications of coinage metal
nanoparticles strongly depend on their optical
properties, arising from localized surface plasmon
resonances (SPRs). The SPRs can be tuned by varying
parameters such as size and shape of nanoparticles,
dielectric environment (refractive index of
medium/solvent and of coating shells), and interparticle
distance. Recently, the layer-by-layer (LbL) technique
has been proposed as a versatile, easy, and inexpensive
bottom-up nanofabrication technique for the preparation
of nanoparticle-containing ultrathin multilayer films. By
employing this technique, individual and collective SPRs can be created from intralayer or interlayer
interparticle interactions. However, in most cases the
LbL technique usually necessitates the deposition of
oppositely charged polyelectrolytes on substrates. This
issue leads to complicated and time-consuming process,
limiting their use in practical applications.In this study,
to overcome the major drawbacks of nanoparticle-
containing LbL thin films, we proposed gold
nanoparticle-containing (AuNP) films of polydopamine
(PDOP) through oxidative polymerization of dopamine.
Seminal work by Messersmith and co-workers depicted that PDOP can bedeposited on almost all types of
inorganic and organic substrates with easily controllable
thickness, robust stability, and excellent
biocompatibility and as a result of its functional groups
including catechol, amine and imine, metallic
nanoparticles may be easily formed in situ in a
controlled manner without the use of any additional
reductants or metallic seed particles [1]. To this end, the
substrates were immersed sequentially into dopamine (2
mg/ml in Tris-buffer) and chloroauric acid (0.1 mg/ml)
solutions until the creation of desired multilayer films.
Surface enhanced Raman spectroscopy (SERS) of the relevant films were investigated in detail.
2. Results and Discussion
According to our previous study, we set the PDOP deposition time as 3 h to form an approximately 10 nm-
thick layer and 12 h for the in situ growth of AuNPs [2].
As shown in Fig. 1, it is observed that the density and
average size of the deposited AuNPs were dramatically
changed with the number of layers. When the number
of layers increased in the fabricated films, the size of the
AuNPs also increased, and average particle size ranged
from 30 nm to 110 nm for the (PDOP/AuNP)2 film and
from 40 nm to 120 nm for the (PDOP/AuNP)3 film. In
UV-vis spectra of films strong absorption peak maxima
were found in the range of 532–572 nm. The emergence
of multilayer films lead to obvious red-shifting and broadening, along with increased absorbances due to
collective SPR characteristics of AuNP-containing
multilayer films with a proper interparticle distance.
Figure 1 Top and cross-section SEM micrographs of (PDOP/AuNP)n LbL films for different layer (n) numbers: n . 1 (a, d), n . 2 (b, e) and n . 3 (c, f), and UV-visible absorption spectra of (PDOP/AuNP)n LbL thin films (g) [3].
In SERS studies (Fig. 2), for the multilayer
(PDOP/AuNP)2 and (PDOP/AuNP)3 films, additional
SERS enhancement was observed compared to the
single layer film ((PDOP/AuNP)1). In those cases, the collective SPR between nanoparticles within adjacent
layers was mainly responsible for the generation of hot
spots with extremely high electric field enhancement.
Figure 2 (a) Representative SERS spectra of methylene blue (MB) on the (PDOP/NP)n LbL thin films with different layer (n) numbers (n . 1, n . 2, and n . 3) and (b) reproducibility of SERS spectra of MB collected on 30 randomly selected spots of (PDOP/AuNP)3 LbL thin films [3].
References
[1] Lee et al. Science, 2007, 318, 426–430.
[2] Akin et al. J. Mater. Chem. B, 2014, 2, 4894–4900.
[3] Yilmaz et al. RSC Adv., 2016, 6, 12638–12641.
Poster Presentation – PP0139
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Rosmarinic acid modified screen-printed electrode for NADH sensor
M. Bilgi1,2, E.M. Sahin2* and E. Ayranci2
1 Department of Chemistry, Çankırı Karatekin University, Çankırı, Turkey
2 Department of Chemistry, Akdeniz University, Antalya, Turkey
*Presenter: melikesahin@karatekin.edu.tr
Abstract
Rosmarinic acid (RA) is a hydroxycinnamic acid
derivative and a naturally occurring phenylpropanoid
that is commonly found in species of the Boraginaceae
family, the subfamily Nepetoideae of the Lamiaceae
family, and in lower plants such as ferns and hornworts.
The antioxidants are redox agents, and both
electrochemical and chemical oxidations of these
compounds have been studied [1]. Dehydrogenase
based biosensor need nicotinamide adenine dinucleotide
(NAD+) as a coenzyme. Reduced form NADH generated in the enzymatic reaction is oxidizing on the
electrode surface at suitable potantial and
electrooxidation of NADH is detected. Electrooxidation
of NADH at high overvoltage causes irreversible
formation of enzymatically inactive forms of NAD+ and
contamination (fouling) of electrode surface due to
adsorption of these products which results in
background currents leading to interferences in real
samples. In order to decrease the high overpotential and
to minimize the side reactions, various mediators,
polymers and nanomaterials (NMs) have been widely used in modification of electrodes [2]. The main aim of
the present research is used by RA as new redox
material to the electrooxidation of NADH at lower
potential. As the sensor application of RA modified
SPCE is utilized determination of NADH.
RA was deposited on SPCE by potential cycling
between -0.1 to +0.8 V for 5 cycles in at a scan rate of
20 mV s-1 a solution containing 1 mM RA, 50 mM pH
7.0 PBS. Figure 1 represents the cyclic voltammograms
of 1 mM NADH and buffer obtained with SPCE/RA. The cyclic voltammograms were obtained in a series of
concentrations of NADH and are given in Figure 2. The
anodic current was an enhancement with the addition of
NADH. NADH was detected amperometrically by
applying a potential of +0.25 V (vs. Ag pseudo
reference electrode). Measured current plotted vs
NADH concentration gave a sensitivity and a
correlation coefficient of 8.82 μA.mM-1 and 0.991,
respectively.
Figure 1. CVs obtained with SPCE/RA at a
scan rate of 50 mV s-1 in 50 mM pH 7.0 PBS
(in 0.1 M KCl) containing no NADH (inner
CV) and containing 1 mM NADH (outer CV)
Figure 2. Dependence of CVs response on
NADH concentration for a SPCE/RA in in 50
mM pH 7.0 PBS (in 0.1 M KCl) at 50 mV s-1.
NADH concentrations are 0.1, 0.25, 0.50,0.75,
1.0, 1.5, 2.0, 3.0, 5.0 mM from inner to outer
cycles, respectively.
References
[1] Park, S.U.; Uddin, M.R.; Xu, H.; Kim, Y.K.; Lee,
S.Y.; Afr. J. Biotechnol., 2008, 7, 4959-4965.
[2] Sahin, M.; Ayranci, E., Electrochimica Acta 166
(2015) 261–270.
-15
-5
5
15
25
-0,1 0,1 0,3 0,5
Cu
rren
t/µ
A
Potential/V
-10
0
10
20
30
40
-0,1 0,1 0,3 0,5
Cu
rren
t/µ
A
Potential/V
Poster Presentation – PP0205
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
The Comparison of the Development and Performance of The Biosensor
For Determination of Aminoglycoside Antibiotics In Animal Products On
The Ultrasensitive Aptamer Based Biosensor
Mert Muhammed Koc1*
, Merve Kucukoflaz1, Yagmur Guler
1, Şengül Kurtuluş and Mustafa Oguzhan Caglayan
1
1Nanotechnology Engineering Department, Cumhuriyet University, Sivas, Turkey
*Presenter: mertmuhammedkoc@gmail.com
1. Introduction
Antibiotics bacteria are chemical compounds that kill or
slow their growth and are useful in treating bacterial
infections. But it consist of a danger as the development
of resistant bacteria against that antibiotic use excessive
or unnecessary use of the drug, Taken together with
residual nutrients consumed through the food chain
antibiotics, super bacteria to form and cause damage to
organs such as the liver and kidney. Therefore,
monitoring of residual levels of antibiotics in the food
chain is important is also a necessity. Also, aminoglycoside antibiotics are ototoxic in terms of
human health and nephrotoxic. Therefore, environ
mental monitoring of antibiotic levels including food
waste, will reduce the risk of forming dangerous multi-
drug resistant strains of bacteria.
2. Materials and Methods
Aminoglycoside antibiotics are ototoxic in terms of
human health and nephrotoxic. Therefore also including
your food remnants, the environ mental monitoring of
antibiotic levels will reduce the risk of developing drug-
resistant bacteria at multivariate dangerous species. İn
many countries in terms of contamination with antibiotics, such as kanamycin and neomycin, are
controlled foods of animal origin. The limit until they
are admitted, on the kanamycin 150ng/ml, and
streptomycin for 500ng/ml, and neomycin for 500ng/ml.
Therefore, the animal source of the determination of
antibiotic residues in foods on the new method are
targeted to improve access. Due to the high affinity of
the aptamers show, kanamycin and neomycin, based on
the aptamer and spectroscopic ellipsometry (SE) and
fortified by surface plasmon resonance - sincere
biosensor was developed using the methods of the full reflection ellipsometry (SPRe-TIRE). Quite different
from each other on the use of specified methods to
optimize both the immobilization has been carried out
of route conditions.
3. Result and Discussion
In this study, toxic effects should both be in the food
chain due to the accumulation and transfer super-
bacteria that can cause it to form aminoglycoside groups
are apta-sensor been implemented with the appointment
of two antibiotics. Aptasensor target is measured can be
converted to form the actual phisicochemical caught
after the change has been preferred on the ellipsometry which will be used as a converter. Ellipsometric round
of two different techniques, spectroscopic ellipsometry
and sincere exact reflection (TIRE) are
compared. When used because the techniques are
slightly different from the sensor surface were followed
two different paths immobilization. Silicon flakes and
gold coated glass slide surface immobilization methods
of the specified aptamer groups on the optimized obtain
this study, the target, the other can compete with
antibiotics residual analysis techniques and the
development of an unlabeled detection methods.
Kanamycin or neomycin using such study presented on
the spectroscopic ellipsometry and ellipsometry sincere
exact reflection of two different types of sensors have
been developed and compared. Such study used all
aptamers and SE with SPRe - TIRE sensors are nearly gave similar analytical results. Determination of the
lowest limit of the kanamycin on the 100 pM, the
highests interest of 4.00 nM, all sensors in the
determination of possible limit there has been between 1
uM. for neomycin lowest LOD 360 pM, the highest
has be 6.88 nM.
Table 1 selectivity of the sensor (For SE)
Sensor Response (Δ)
Aptamer Tobramycin
(not avaible)
Tobramycin
(available)
Tobramycin
(purely)
AntiKnm3 4.3068±0.057 4.6083±0.087 0.3015±0.100
AntiNeo5 4.8776±0.087 5.0727±0.131 0.4389±0.116
Table 2 selectivity of the sensor (For SPRe-TIRE)
Sensor Response (Δ)
Aptamer Tobramyci
n (not
avaible)
Tobramyci
n
(available)
Tobramycin
(purely)
AntiKnm
1
7.4985±0.0
70
8.5337±0.13
4
0.2481±0.09
2
AntiNeo1 6.49622±0.
134
8.6066±0.22
9
0.60660±0.1
48
It should be noted, the connection of the sensor
structure must be a straight answer measure. Therefore
offered ranges, are expressed as a range measure. The
result between the detection limit of the working range,
the lowest detection limits obtained in this study,
working in a relatively narrow range of enumeration.
Obtained sensor performance, although kanamycin and neomycin the under limit of the (500ng/ml) wich
designated the clipboard, at the same time, kanamycin
and neomycin on reported ELİSA method based,
when compared (respctively 0.83ng/mL and 2.73ng
/mL) are compared inside limits.
Poster Presentation – PP0207
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Investigation of the use of Periodic Nanobump Surfaces for Detecting Myoglobin
Protein
Merve Çelik1*, Sevde Altuntaş1 and Fatih Büyükserin2
1 Biomedical Engineering Graduate Program, TOBB University of Economics and Technology, Ankara, Turkey 2 Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Turkey
*Presenter: merve.celik@etu.edu.tr
Abstract
Acute myocardial infarction is the most common cause
of mortality worldwide.[1] Because of the difficulties of
distinguishing the physical symptoms and the need for
urgent medical intervention, early diagnosis of this
disease is crucial. Apart from the physical symptoms of
acute myocardial infarction, abnormalities in the ST
segment of electrocardiogram of the patient and the
concentration of some proteins like myoglobin which
starts to be secreted 1 hour after the symptoms and
troponin which starts to be secreted 3-6 hours after the symptoms is the markers of this disease.[2] Current
protein detection methods like ELISA and
electrophoresis are high-cost and requires expertise.[3] It
is crucial to design a simple and ultra sensitive protein
detection method for early diagnosis in order to increase
the survival rate of the patients and overcome the
problems mentioned.
Surface-enhanced Raman spectroscopy (SERS) is a
powerful technique used for molecular analysis that
provides molecular fingerprint information and has the
potential to detect down to single molecule.[4] Despite
the ultra sensitivity and specificity of this technique,
SERS can not be used as a routine sensing tool.[5] This
is because of the poor reproducibility of SERS signals.
In order to provide highly reproducible SERS signals,
reproducible strong SERS-active substrates should be
designed.
Properties of an ideal SERS substrate are stated in
previous researches.[5] The most important properties
are high signal enhancement and signal reproducibility
which periodic nanostructured arrays satisfy. In the
current studies these periodic nanostructures are usually
created by lithography.[6] But this technique is time consuming, high cost and can not be applied to large
surface areas.
In the proposed system, nanostructured anodic
aluminum oxide (AAO) membranes are used for SERS
signal enhancement. These membranes are a class of
special biomaterials that are produced from high purity aluminum via two step anodization methods. The
production of the substrates are easy and highly
controllable with this method and compared to
lithography it is cost-effective. It is possible with this
procedure to produce AAO membranes with different
column structures and thicknesses depending on voltage
and anodization time. The produced membranes are
used aluminum-free and the nanobumpy barrier side of
the membrane is used as the SERS platform. Then this
barrier side will be treated with acidic solutions to form
crater on the surface to create a different surface
topography with potentially enhanced SERS signals as
predicted with previous simulations.
Figure 1 SEM images of the produced images
nanobumpy array(left), nano crater array (right)
The prepared surfaces will be modified with Au and the
Raman-active dye, Rhodamine 6G. SERS signal
enhancements of the surfaces will be determined. In the
last part of this study protein detection will be
performed with the surface that has the highest signal
enhancement. As the earliest biomarker of acute
myocardial infarction, in order to achieve early
diagnosis myoglobin will be detected on this biosensing
platform.
References
[1] Straface, Angela L., et al. "A rapid point-of-care cardiac
marker testing strategy facilitates the rapid diagnosis and management of chest pain patients in the emergency department." American journal of clinical pathology 129.5 (2008): 788-795. [2] Newby, L. Kristin, et al. "Value of serial troponin T measures for early and late risk stratification in patients with acute coronary syndromes." Circulation 98.18 (1998): 1853-1859. [3] Sharma, Vikash, et al. "Electrochemical impedance
immunosensor for the detection of cardiac biomarker Myogobin (Mb) in aqueous solution." Thin Solid Films 519.3 (2010): 1167-1170. [4] Choi, Dukhyun, et al. "Self Organized Hexagonal Nanopore SERS Array." Small 6.16 (2010): 1741-1744. [5] Cialla, Dana, et al. "Surface-enhanced Raman spectroscopy (SERS): progress and trends." Analytical and bioanalytical chemistry 403.1 (2012): 27-54.
[6] Banholzer, Matthew J., et al. "Rationally designed nanostructures for surface-enhanced Raman spectroscopy." Chemical Society Reviews 37.5 (2008): 885-897.
Poster Presentation – PP0208
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Determination of Spread-Based Biosensor TIRE Multiprecision micropatterned,
and Development of Oligonucleotide and Protein Immobilization Method for
Chip and the Sensor Performance
Merve Kucukoflaz1*, Mert Muhammed Koc1 , Şengül Kurtuluş1 ,Yagmur Guler1 and Mustafa Oguzhan Caglayan1
1Nanotechnology Engineering Department, Cumhuriyet University, Sivas, Turkey
* Presenter: kucukoflazmerve@gmail.com
1. Introduction
Biosensors provide reliable and quick response analysis
achieved with the combination of appropriate
transducers and utilization of selectivity and specifity of
bioaffinity. However, it is required, the reactions those
are fast and selective, occuring on biosensors, to be
defined quickly with the same accuracy. Surface
plasmon resonance (SPR) and ellipsometry based on
optical transducers provide an accurate and an on-line
analysis. In this study, development of a micro-
patterned biosensor system available for multiple and
qualitative/quantitative determination of one or more
bio-molecules with a single and modified biosensor chip which implements both of total internal reflection
ellipsometry and surface plasmon resonance techniques
was aimed.
2. Materials and Methods
In the first step, a multiple step micro-patterning was
applied on designed biosensor chip, then, self assembled
monolayer was formed by using various chemical
methods on micro-patterned biosensor chip, and finally
by using “layer by layer” approach, appropriate probes
selected from bio-affinity pairs were immobilized on
formed monolayers. For this purpose, these steps were performed, briefly: (a) combination of surface plasmon
resonance technique and total internal reflection
ellipsometry; (b) application of different metal films
yielding surface plasmon resonance phenomena on
same chip surface; (c) micro-patterning of surface
plasmon resonance enchanted (SPRe) total internal
reflection ellipsometry (TIRE) sensor chip; (d)
application of appropriate modification on micro-
patterned chip surface by layer by layer approach; and
(e) evaluation of performance of produced sensor chip.
This project consists of 4 work packages (IPs). In the
IP1, substrate preparation for sensor chip and micro-patterning of this chip surface by photolithography
technique were performed. In the IP2, micro-patterned
chip substrate was functionalized by using protective
and multi-step modification method. Oligonucleotide
probe which has specific sequence for Avian Influenza
(H1, N1) and Protein A probe were immobilized on to
functionalized micro-patterns to get a specific pattern
(IP3). Finally, performance of designed sensor chip on
SPRe-TIRE configuration was evaluated. At this step,
sensor signal was acquired against reaction duration,
while complementary ODN (target) and H-IgG (target) molecules are interacted with the sensor chip under
certain conditions. Bio-molecular determination was
realized in a short time and with small concentrations of
target; by using the advantages of SPRe-TIRE
phenomena and detection limit decrement using
appropriate sensor chip design giving SPR.
3. Results and Discussion
In this study, avian influenza (bird flu) Influenza A
group pathogen assay for the gradual immobilization
techniques of a sensor that can run as simultaneous
protein sensor with synthetic ODN-based sensor
micropattern that eseasl array (array) structure has been
developed.
Protein-protein interactions based on protein A-IgG
interaction is modeled for the second micropattern
Detection limits for IgG was determined to be 80 nM.
Both sequences in 100 minutes on the same chip and
ODN target protein produced a signal that reaches
equilibrium.In addition, the sensor only when used for
on-off signal of the chip (on a signal to noise ratio) and ODN as well as the time appointed for the target protein
is around 30 minutes.for InfA
Figure 1 – 2B- Ellipsometric image of the micro-
patterned substrat
es
Figure 2 – IgG- interaction of Protein A sensor
response.
Poster Presentation – PP0209
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Evaluation of Methods for the Detection of Oxygen in
Packaged Food Products
Meryem Yılmaz
1*, Elif Atay
1 and Aylin Altan
1
1Department of Food Engineering, Mersin University, Mersin, Turkey
*Presenter: meryemyilmaz_m@hotmail.com
Abstract
Detection of oxygen is very important to packaged food products. Food has respiration capability and the gas
composition in the package can change as a result of
interaction of food with its environment [1]. Therefore,
oxygen in the gas composition can be one of the main
cause of food spoilage, resulting in aerobic microbial
growth, oxidation of food components such as lipids
and micronutrients, and changes in color, flavor, bad
smell, etc [2]. Therefore, intensive studies have been
made to develop oxygen sensors and oxygen indicators
which can simply detect oxygen gas. In contrast to
oxygen sensors which are able to detecting oxygen
molecules and transforming the detecting information into electrical signals in a quantitative manner, oxygen
indicators are described as devices that enable people to
recognize changes in the optical absorbance of organic
dyes or pigments according to the oxygen concentration
in the form of changes in color in a semi-quantitative or
a rather qualitative manner. Therefore, oxygen
indicators can offer many advantages over oxygen
sensors due to their impregnability from electrical and
electromagnetic interferences, strength, tiny size and
their low expense [3]. One of the established method for
the detection of oxygen, fluorescent-based oxygen sensors have been used to remote measurement of
headspace gases inside packaged products. Sensors
designed in this study normally have been taken place a
fluorescent or phosphorescent dye encapsulated in a
solid polymer matrix and added to a suitable support
material. If there are molecular oxygen in the packaged
products, it quenches the luminescent dye and can be
quantified against predetermined calibrations. The
process is reversible and there are not side products [4].
Another method used for the detection of oxygen is
colorimetric method. With colorimetric method,
methylene blue based on the nafion film has been prepared and chemical reactions in contact with active
oxygen species have been estimated. Methylene blue
used for colorimetric oxygen indicator has been
preferred for that one of redox dyes. Therefore, in this
study, decolorization mechanism of the film due to
exposure of the active oxygen species has been
discussed [5].
Other method used for the detection of oxygen, UV-
activated oxygen indicator has been developed by using
electrospinning in this study. By dispersing TiO2
nanoparticles, glycerol and methylene blue in poly ethylene oxide solution using aqueous ethanol as a
solvent, the oxygen indicator has been prepared. As a
result, this study showed that TiO2-based indicator has
been promising for oxygen detection in modified
atmosphere packaging applications [6]. There are many established methods for the detection of
oxygen, involving colorimetric, fluorescent and
conductivity methods, however, such instruments are
costly, required trained users to operate, lack of
portability and time consuming to allow full quality
assurance. Therefore, there is an increasing interest in
cheap and simple developments today for using oxygen
indicators [6-7].
In recent years electrospinning method is an open for
improvement and popular technology because it offers
advantages such as control over morphology, porosity
and composition by using simple equipment. Nowadays, this method can be used for production of
biosensors to detect of oxygen in packaged products.
References
[1] De Jong, A.R., Boumans, H., Slaghek, T., Van
Veen, J., Rijk, R., Van Zandvoort, M. 2005. “Active and
intelligent packaging for food: Is it the future?” Food
Additives & Contaminants, 22: 975-979.
[2] Vermeiren, L., Devlieghere, F., Van Beest, M., De
Kruijf, N., Debevere, J. 1999. “Developments in the
active packaging of foods”, Trends in Food Science
Technology, 10:77-86. [3] Sumitani, M., Takagi, S., Tanamura, Y., Inoue, H.
2004. “Oxygen Indicator Composed of an
Organic/Inorganic Hybrid Compound of Methylene
Blue, Reductant, Surfactant and Saponite”, Analytical
Science, 20: 1153-1157.
[4] Hogan, S.A., Kerry, J.P. 2008. “Fluorescent Based
Oxygen Sensors”, In Smart Packaging Technologies for
Fast Moving Consumer Goods.
[5] Iwamori, S., Nishiyama N., Oya, K. 2015. “A
colorimetric indicator for detection of hydroxyl radicals
in atmosphere using a methylene blue dye based on
nafion film”, Polymer Degradation and Stability, 123:131-136.
[6] Suramya, D. F. Mihindukulasuriya, Loong-Tak, L.
2013. “Oxygen detection using UV-activated
electrospun poly (ethylene oxide) fibers encapsulated
with TiO2 nanoparticles” Journal of Materials Science,
48: 5489-5498.
[7] Wolfbeis, O. S. 1991.“Fibre Optic Chemical Sensors
and Biosensors”, CRC Press.
Poster Presentation – PP0211
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Sensitive detection of Melanoma-associated antigen by regenerative
immunosensor based on ITO modified with self-assembled silane
monolayers
Aslı Gündoğdu1, Münteha Nur Sonuç Karaboğa
2,3* and Mustafa Kemal Sezgintürk
1
1 Department of Chemistry, Namik Kemal University, Tekirdag, Turkey
2 Department of Chemistry , Institute of Science, Namik Kemal University, Tekirdag, Turkey 3 School of Health, Namik Kemal University, Tekirdag, Turkey
*Presenter: mnsonuc@nku.edu.tr
1. Introduction
Melanoma-associated antigens (MAGE), a group of
well-characterized members of the Cancer/testis
antigens (CTA) family. The MAGE family has been
divided into two big categories: MAGE-I and MAGE-II
based on their tissue-specific gene expression and
chromosomal location. [1-2] Most of them are highly
expressed in various forms of cancer, normally
expressed in testis, trophoblast, and placenta. [3] Since
MAGE antigens are strictly tumor-specific, they have
the potential to become the ideal targets for cancer immunotherapy. [4] To date, the protein expression of
the MAGE family and their correlation with clinico-
pathological characteristics has been carried out in
various solid tumors including hepatocellular
carcinoma, lung cancer , renal cell carcinoma, epithelial
ovarian cancer , gastric and colorectal cancers , and
lymphoma. In addition, a larger cohort exploration
concerning MAGE expression was also performed in
head and neck squamous cell carcinoma (HNSCC). [5]
From this view, present study aimed to a novel,
disposable and, cost-effective immunosensor based on
indium tin oxide (ITO) sheets modified with silane
chemistry to selectively analyze MAGE-1, a potentional
biomarker.
2. Results and Discussion
In present study, the novel and simple biosensor system was developed to detect MAGE. Carboxyethyl silane
etriol was used firstly as a self assembled monolayer
agent. The activation of -COOH groups was carried out
using 1-ethyl-3-(3-dimethylaminopropyl) carbodimide
(EDC) /N-hydroxysuccinimide (NHS) couple.
Analytical characteristics of constructed biosensor such
as square wave voltammetry, linear determination range,
repeatibility, reproducibility and regeneration of
biosensors are determined. All characteriation steps are
monitored by electrochemical impedance spectroscopy
(EIS) and cyclic voltammetry (CV). The presented biosensor has wide determination range (0.004 pg/mL-
0.2 pg/mL). To investigate long shelf life of the
fabricated biosensor, the immunosensors were stored at
4°C for periods ten weeks. Beside, binding kinetics of
MAGE to anti-MAGE is monitored by single frequency
technique in real time. Moreover, Kramers Kronig
transformations were performed for validation of
obtained EIS data in all steps of biosensor fabrication.
In the end, the presented biosensor was performed to
real serum and compared with standart literature
findings. Morphological characteristics of constructed
biosensor were observed by scanning electron
microscopy (SEM).
Consequently, the present biosensor system has
significant advantages and these biosensor give hope in
terms of applicability in clinical diagnosis of some
cancer types.
Acknowledgement: Support from TÜBİTAK (The
Scientific and Technological Research Council of
Turkey, Project number: 113 Z 678) is greatly
acknowledged.
References
[1] Xu X, Tang X, Lu M, Tang Q et al., Exp Mol
Pathol. 2014, 97(3):579-84
[2] Sang M1, Wang L, Ding C, Zhou X, Wang
B, Cancer Lett. 2011 Mar 28;302(2):85-90
[3] Achim A. Jungbluth, Wilson A. Silva, Jr., Kristin
Iversen, Denise Frosina Cancer Immun. 2007; 7:
15.
[4] Nathalie Vigneron, Biomed Res Int. 2015; 2015:
948501
[5] Achim A. Jungbluth, Klaus J. Busam , Denise
Kolb International Journal of Cancer Volume
85, Issue 4, pages 460–465
Poster Presentation – PP0213
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Hydrodynamic Trapping of Micro-Liter Droplets and Biological Samples
Adil Mustafa1, Nima Bavili*1, Melikhan Tanyeri2, Ahmet Erten3 , Alper Kiraz1
1 Department of Physics, Koç University, İstanbul, Turkey 2 Department of Electrical Engineering, Özyeğin University, İstanbul, Turkey
3 Department of Electrical Engineering, Osmaniye University, Osmaniye, Turkey
*Presenter: nbavili16@ku.edu.tr
1. Introduction
Hydrodynamic trapping has been introduced recently as
a powerful tool for trapping and manipulation of micro
beads, DNA molecules, cells or generally any
micron/nano sized particles. The technique finds its
novelty in its non-contact based trapping.
2. Experiments
One of the major and most recent applications of this
method is investigating the dissolution of liquid micro
droplets in aqueous solutions [1]. One parameter characterizing the dissolution is diffusion coefficient or
in other terms, mass transfer coefficient. Diffusion
coefficient is an important parameter for industrial
applications such as separation/sorting processes and
drug delivery/design [2-4]. Work is under progress on
implementing hydrodynamic trapping method for
biological samples such as RBC. Experiments are also
being performed on measuring deformation of
hydrodynamically trapped low surface tension micro
droplets, which is also applicable to biological samples.
3. Results
We have observed the dissolution using micro droplets
of benzyl benzoate and n-decanol trapped in water and
surfactant (DSS) solution at different flow rates. The
results show that rate of dissolution of micro droplets increases at high flow rates. The rate of dissolution also
changes from benzyl benzoate to n-decanol with
ndecanol dissolving faster than benzyl benzoate. The
results also showed that dissolution also is affected by
amount of surfactant in the solution. Obtained data from
experiments were analyzed and used to modify the
Epstein-Plesset equation [5].
References
[1] A. Mustafa, A. Erten, R. M. A. Ayaz, O.
Kayıllıoğlu, A. Eser, M. Eryürek, M. Irfan, M.
Muradoglu, M. Tanyeri, and A. Kiraz, Enhanced
Dissolution of Liquid Microdroplets in the Extensional
Creeping Flow of a Hydrodynamic Trap. Langmuir, 2016, 32 (37), pp 9460–9467
[2] Duncan, P. B.; Needham, D. Microdroplet
dissolution into a second-phase solvent using a
micropipet technique: test of the Epstein-Plesset model
for an aniline-water system. Langmuir 2006, 22,
4190−4197.
[3] Harland, R. S.; Gazzaniga, A.; Sangalli, M. E.;
Colombo, P.; Peppas, N. A. Drug/polymer matrix
swelling and dissolution. Pharm. Res. 1988, 5, 488−494.
[4] O’Donnell, P. B.; McGinity, J. W. Preparation of
microspheres by the solvent evaporation technique. Adv. Drug Delivery Rev. 1997, 28, 25−42. [5] Epstein,
P.; Plesset, M. On the Stability of Gas Bubbles in
Liquid-Gas Solutions. J. Chem. Phys. 1950, 18,
1505−1509.
Poster Presentation – PP0252
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Determination of protein activated kinases 2 (PAK 2) by a sensitive
electrochemical biosensor
Nergiz Kılınç1* and Mustafa Kemal Sezgintürk1
1 Namik Kemal University, Faculty of Arts and Science, Chemistry Department, Biochemistry Division, Tekirdag,
Turkey
*Presenter: ylmz.nrgz@hotmail.com
1. Introduction
Among the many different signaling molecules that
regulate cell survival and cell death are the p21
activated protein kinases (PAKs). PAKs are activated in
re
sponse to extracellular signals and regulate cell shape
and motility as well as cell survival and programmed
cell death. The mammalian PAK family consists of six members that can be divided into two subfamilies
according to sequence homology. The first subfamily
consists of PAK-1 (alpha-PAK), PAK-2 (gama-PAK),
and PAK-3 (beta-PAK). PAK-1 and PAK-3 are tissue-
specific with the highest levels in brain, whereas PAK-2
is ubiquitous. The second subfamily consists of the
more recently identified PAK-4, PAK-5, and PAK-6.
p21-activated protein kinases (PAKs) are a family of
serine/threonine protein kinases that are activated by
binding of the p21 G proteins Cdc42 or Rac. The
ubiquitous PAK-2 (gama-PAK) is unique among the PAK isoforms because it is also activated through
proteolytic cleavage by caspases or caspase-like
proteases. In response to stress stimulants such as tumor
necrosis factor alfa or growth factor withdrawal, PAK-2
is activated as a full length enzyme [1]. Silica gel is an
amorphous inorganic polymer composed of siloxane
groups (Si-O-Si) in the inward region and silanol groups
(Si-OH) distributed on the surface. Modification of
silica gel by inorganic or organic functional groups has
been the subject of considerable interest due to many
possibilities of application. Surface modifications are
usually achieved with silanization using an appropriate organosilane agent. One of the most widely applied
organo-functional alkoxysilanes is 3-
glycidoxypropyltrimethoxysilane (3- GPTMS). Its
epoxide groups are convenient for the covalent binding
of enzyme and proteins. The O-C and N-C bonds
formed by the epoxide groups are extremely stable, so
that the epoxide-containing polymers can be used for
the immobilization of enzyme and proteins [2].
2. Result and Discussion
In this study, we designed a novel biosensor to detect
PAK-2 biomarker constructed on modified indium tin oxide (ITO) disposable electrodes. Anti-PAK2 was
immobilized through covalent with 3-
glycidoxypropyltrimethoxysilane which formed a self-
assembled monolayers (SAMs) on modified ITO
electrodes. Analytical characteristics such as square
wave voltammetry, linear determination range,
repeatibility, reproducibilty and regeneration of
biosensors were determined. All characterization steps
were monitored by Cyclic voltammetry (CV), and
electrochemical impedance spectroscopy (EIS)
techniques. To achieve reproducible and repeatable
biosensor system, all parameters such as SAMs concentration, antibody concentration and antibody
incubation time were optimized. The presented
biosensor has wide determination range (5 fg-75
fg/mL).
Acknowledgement: We are thankful for financial
support from the Scientific and Technological Research
Council of Turkey (TÜBİTAK, Project number: 113 Z
678).
References
[1] Rolf Jakobi, Corine C. McCarthy, Mark A. Koeppel, and Daniel K. Stringer.’’ Caspase-activated PAK-2 Is
Regulated by Subcellular Targeting and Proteasomal
Degradation*.Vol. 278, No. 40, Issue of October 3, pp.
38675–38685, 2003 Printed in U.S.A.
[2] Seung Won Park, Jeewon Lee, Suk In Hong, Seung
Wook Kim.’’ Enhancement of stability of GL-7-ACA
acylase immobilized on silica gel modified by epoxide silanization. Process Biochemistry 39 (2003) 359/366
Poster Presentation – PP0214
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation of Poly(thionine) Supported Platium Nanoparticles For
Electrocatalytic Applications
N. Çoşkun Kurt1* and M. Sönmez Çelebi1
1Department of Chemistry, Faculty of Science and Arts, Ordu University, 52200, Ordu, Turkey
*Presenter: kurtnesrinn@gmail.com
1. Introduction
Fuel cells are regarded as promising energy sources for
the future to replace the traditional systems which use
fossil fuels. During the operation of a fuel cell, the
chemical energy of the fuel (hydrogen, methanol,
ethanol, formic acid, etc.) and the oxidant (oxygen gas
or hydrogen peroxide) is catalytically converted to
electricity at the active interface regions between the
electrodes and the electrolyte. Fuel is oxidized in the
anode whereas reduction of the oxidant takes place in
the cathode [1,2] The catalyst layer on the electrodes
contains precious (often Pt) or non-precious metal particles which are generally supported on a suitable
material. Pt-based catalysts are used frequently for
construction of both anodes and cathodes while non-
precious metals are generally used in the cathode
compartment. Therefore, electrode materials are of great
importance for increasing the efficiency and reducing
the cost of a fuel cell system. Metal nanoparticles have
interesting and unique properties compared to larger
corresponding metal particles. Metal particles with nano
and uniform sizes have many applications in optics,
electronics, magnetic devices and as catalysts,
photocatalysts, adsorbents and sensors. Generally, the small particle size and high dispersion of metal particles
will result in high electrocatalytic activity [3]. Metal
nanoparticles supported on functional polymers have
many advantages such as generation of metal
nanoparticles with a controlled size and size distribution
and influencing the chemical behavior of metal
nanoparticles via interaction with the polymer bound
functional groups [4]. In the current work, synthesis of
poly(thionine) (PTH)-supported Pt particles on pencil
graphite electrode was described. Pt particles were
incorporated into the polymer matrix via cyclic voltammetric scans in aqueous K2PtCl4 solution without
supporting electrolyte. The Pt complexes immobilized
in the redox polymer matrix were then reduced by
chemical reduction using hydrazine as the reducing
agent. The Pt nanoparticles were tested for
electrocatalytic oxidation of methanol for fuel cell
applications.
2. Experimental
In electrochemical studies, a pencil graphite electrode
(PGE) (r = 0.25 mm) was used as the working electrode.
A saturated calomel electrode (SCE) was used as the
reference electrode and a Pt wire was used as the
counter electrode. Cyclic voltammetry studies were
carried out with CH Instruments System, Model 600E.
3. Results and discussion
Thionine was electrochemically polymerized onto the
PGE surface by cyclic voltammetry from aqueous
solution of TH containing 0.5 M H2SO4 as the
supporting electrolyte. Polymerization profile of PTH is
given in Figure 1.
Figure 1 Polymerization profile of TH
Pt particles were incorporated into the polymer matrix via cyclic voltammetric scans in 2 mM K2PtCl4 solution
without supporting electrolyte. The Pt complexes
immobilized in the redox polymer matrix were then
reduced by chemical reduction using hydrazine as the
reducing agent.
The PTH supported Pt nanoparticles prepared as
described above showed excellent catalytic activity
towards electrooxidation of methanol (Figure 2). It can
be stated that PTH supported Pt nanoparticles can be
used as anode catalysts for direct methanol fuel cells.
Figure 2 CV of 0.5 M methanol + 0.5 M H2SO4
References
[1] J. Yuan, B. Sunden, Int J Heat Mass Tran, 69, 358 (2014)
[2] Y, Wang, K.S. Chen, J. Mishler, S.C. Cho, X.C. Adroher Appl Energ, 88,
981 (2011)
[3] M. Adlim, M.A. Bakar, K.Y. Liew, J. Ismail, J. Molecular Catalysis: A
Chemical, 212, 141 (2004).
[4] M. Kralik and A. Biffis, J. Molecular Catalysis: A Chemical, 177, 113
(2001).
Poster Presentation – PP0215
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Molecularly Imprinted Electrochemical Sensor for Selective Determination of
Proline
Nihal Ermiş1*, Melike Baskaya and Nihat Tinkiliç1
1 Department of Chemistry, Ondokuz Mayıs University, Samsun, Turkey
*Presenter: nihal.ermis@omu.edu.
tr
1. Introduction
Proline is a very important amino acid because of its
vital role in protein synthesis and structure. Besides it
takes part in wound healing, antioxidative reactions [1].
In general, molecular imprinting method is used via
polymerization of proper monomers around a selected
template. By using an elution agent, template molecules
leave complementary cavities to its three dimensional
structure. On interaction with the imprinted polymer
and template molecule containing solution, via these
cavities polymer behaves as a recognition element. [2] Through mixing this method and electrochemical
techniques, analyte selectivity and specifity can be
gained. In this study, the fabrication of a highly
selective and sensitive proline sensor was investigated
using a polypyrrole (PPy) polymer as an artificial
recognition element. Pyrrole and piroline were used as
the functional monomer and template molecule,
respectively. Electropolymerization on gold electrode
was used to prepare a novel sensor for detecting piroline
without any extra reagent like enzyme or mediator.
2. Experimental
All electrochemical experiments and
electropolymerization were performed on a VersaStat 3
electrochemical system (Princeton Applied System)
connected to a personal computer. The three-electrode
system was consisted of Au (1.6 mm in diameter),
Ag/AgCl/KCl (saturated) electrode and Pt wire, as
working, reference and auxillary electrode, respectively.
The surface of the gold electrode was polished on a
microcloth with 1.0 and 0.05 μm aqueous slurry of alumina. After this it was cleaned in an ultrasonic bath
in water for 5 min to remove any particles on the
surface and then allowed to dry at room temperature.
The electrosynthesis of PPy film was performed by
cyclic voltammetry (CV), between -0.2 and 1.2 V vs.
Ag/AgCl, at a scan rate of 100mV/s. Under same
conditions, without template molecule a non-imprinted
polymer (NIP) was synthesized in order to examine
difference. For electrochemical characterization of MIP
and NIP modified electrode, CV was used.
Electroanalytical measurements were performed with different concentrations of piroline solutions between 1
and 25 nM with square wave voltammetry (SWV)
technique. The selectivity of the imprinted electrode to
tyrosine was evaluated by SWV with the other two
similar molecules, leucine and valine . After template
removal, MIP modified electrodes were immersed in
solutions of this similar molecules
The prepared imprinted sensor was applied for the
detection of piroline levels in honey samples with
standart addition method. Honey was obtained from a
local market. As a comparative study, piroline content in
honey was analysed through Ough method also. The
results were satisfactory.
3. Results and Discussion
Electrochemical characterization of MIP electrode was
made via CV technique as seen on Figure 1. Same
technique was also used to show up the difference between NIP and MIP modified electrodes. According
to the results of selectivity analysis, the adsorption
capacity of NIP modified electrode was almost the same
for each molecule while MIP electrode showed higher
selectivity to proline instead of other selected
molecules.
Figure 1 Difference between bare and MIP modified electrode (blue-bare ;red-MIP
electrode)
Consequently a novel sensor which can detect piroline,
in a wide range levels and lower detection limit was
synthesized. According to the results specificity,
sensitivity, reproducibility were also good and through
MIP method higher selectivity and sensitivitiy gained.
References
[1] Wu Guoyao. et al. Proline and hydroxyproline metabolism: implications for animal and human nutrition (Amino Acids. 2011 Apr; 40(4): 1053–1063 [2] Vasapollo G. et al. , Molecularly Imprinted Polymers : Present and Future Perspective, International Journal of Molecular Sciences 12 (2011) 5908-5945
0 0,2 0,4 0,6 0,8
Cu
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t (u
A)
Volt (V)
Poster Presentation – PP0216
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Guanin Signal Enhancement at DNA Biosensor Using Metal Nanoparticules-
Mixed Silica Gel: Application to Hybridization Detection on Biosensor Surface
Nilay Aladag Tanik1*, Elif Demirkan1 and Yakup Aykut2
1 Department of Biology, Uludağ University, Bursa, Turkey
2 Department of Textile Engineering, Uludağ University, Bursa, Turkey
*Presenter: naladag@gmail.com
1. Introduction
In this study, we have detected the hybridization electrochemically on the pencil graphite electrode
(PGE) surface and we used to cobalt (Co) nanoparticles
and silica gel for the signal enhancement. For
determining the mutation or polymorphism, RFLP, RT-
PCR, and DNA sequencing methods are generally used.
But, these methods are expensive and they also requires
expertise and quite time-consuming sample preparation
processes. It was found that to be possible the detection
of hybridization with label-free methods which are
based on a guanine signal.
2. Experimental
Oxidation signal of most electroactive and stable DNA’s
base, guanine, approximately at about +1.0V is used in
this study. It is the first time that pencil graphite
electrode (PGE) surface is coated with silica gel which
is containing metal nanoparticles. PGE modification
was performed by immersing the PGE in ultrapure
water containing different concentration of silica gel
with different concentration of silver, zinc and cobalt
nitrate salts. After the PGE surfaces coated with silica,
PGEs were placed outside to dry. Probe was
immobilized onto the modified PGE containing probe.
After immobilization, probe-modified PGEs were rinsed for the removing of the unbound DNA at the electrode
surface. Probe modified PGE were immersed into the
target solutions and waited at the room temperature for
immobilization. After hybridization, non-specific
adsorption effects were minimized with the following
washing step. The treated and washed electrode was
transferred into ABS (pH 4.80) and the oxidation signal
of guanine was measured by using DPV in ABS by
scanning +0,75 to +1,25 V. Silica gel and metal ion
concentrations, selection of buffer solution for probe,
for hybridization and for measurement, probe and target concentrations, probe immobilization time,
hybridization time and washing time after the
hybridization were studied in order to find optimum
analytical performance of the developed sensor.
3. Results and Discussion
For the determining of optimum operation conditions, it
was based on that the oxidation signal of guanin signal
at the single-strand DNA (ssDNA) is more than the
signal at the double-strand DNA (dsDNA). The
conditions which give the best possible distinction
between the ssDNA, dsDNA were determined as the
optimum conditions of assay.
In Fig. 1, we compared the guanine signals obtained
from probe by using only silica gel, silver, cobalt, zinc nitrate salts and silica gel with silver, cobalt, zinc nitrate
salts. First of all, 20% silica gel, silver, cobalt, zinc
nitrate solutions and silica gel solution with 20% silver,
cobalt, zinc nitrates were prepared in ultrapure water.
The highest signal ratio was observed with solution of
silica gel and cobalt nitrate salts and this surface
modification was used for further experiments.
Figure 1. The guanine signals and percentage increase
guanine signals of probe coated surface under different
surface modifications.
Figure 2. Voltammograms of guanine signals
4. Conclusions
These results showed that the developed biosensor
selectively connect to the target and showed that it is
possible to determination of hybridization. Our method
is easy to apply, no need to expensive equipment, fast
response system, and no using of any toxic or
radioactive agents. For these reasons, it is powerful
alternative to classical methods.
Poster Presentation – PP0217
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Self-Powering Biosensors for Biofuel Cell Applications
Nilgün Dükar1*, Mehmet Yılmaz2, Gökhan Demirel2 and Filiz Kuralay1
1Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey
2Department of Chemistry, Faculty of Sciences, Gazi University, 06500 Ankara, Turkey
*Presenter: dukarnilgun@gmail.com
Abstract
Biofuel cell (BFC) is a type of fuel cell that uses
microorganisms to produce electricity, rather than
precious metals. They work on the same general
principles as all fuel cells: use a catalyst to separate
electrons from a parent molecule and force it to go
around an electrolyte barrier to generate an electric
current. There are 2 types of biofuel cells: Enzymatic
biofuel cells and microbial fuel cells.
An enzymatic biofuel cell is a specific type of fuel
cell that uses enzymes as a catalyst to oxidize its fuel, while a microbial fuel cell is a bio-electrochemical
system that drives a current by using bacteria and
mimicking bacterial interactions found in nature.
Enzymatic biofuel cells have attracted considerable
interest owing to their ability to provide sustainable
energy from renewable fuel sources under mild
conditions [1-5]. The ability to engineer these devices to
process various renewable biochemical species holds
considerable promise for the utilization of BFCs as
implantable power sources for biomedical devices.
In this study, we describe a self-powered enzyme- based
biosensors for biofuel cell applications (Figure 1). The
anode of the study consisted of a glucose oxidase (GOx)
entrapped peptide nanostructures (using diphenylalanine
peptides) modified screen printed gold electrode. The
enzyme immobilized nanostructured anode used glucose
as the fuel and Meldola’s Blue as the mediator. The
vertical aligned peptide nanostructures were fabricated
in a conventional physical vapor deposition system onto
the electrode.6 Then, GOx immobilization was
performed onto the electrode. Lactate dehyrogenase (LDH) entrapped poly(3,4-ethylenedioxythiophene)
coated gold electrode was used as the cathode material
of the study. 3,4-ethylenedioxythiophene monomer was
electropolymerized in the presence of LDH at a constant
potential of +0.8 V vs. Ag/AgCl onto the electrode.
Acknowledgments: F. Kuralay acknowledges Turkish
Academy of Sciences (TÜBA) as an associate member
and TÜBA-GEBİP programme.
Figure 1 Schematic representation of the work
References
[1] M. Zhou, N. Zhou, F. Kuralay, J.R. Windmiller, S.
Parkhomovsky, G. Valdes-Ramirez, E. Ktaz, J.
Wang, Angew. Chem. Int. Ed. 51 (2012) 2686.
[2] M. Zhou, F. Kuralay, J.R. Windmiller, J. Wang, Chemical Communications 48 (2012) 3815.
[3] E. Katz, A.F. Bückmann, I. Willner, J. Am. Chem.
Soc. 123 (2001) 10752.
[4] Y. Hu, Y. Zhang, C. Xu, L. Lin, R.L. Snyder, Z.L.
Wang, Nano Letters 11 (2011) 2572.
[5] M. Gamella, N. Guz, S. Mailloux, J.M. Pingarron,
E. Katz, Electroanalysis 26 (2014) 2552.
[6] G. Demirel, U. Tamer, Nanotechnology 23 (2012)
225604.
Poster Presentation – PP0218
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Biosensor for Penicillin G Detection
Nilgün Dükar1* and Filiz Kuralay1
1Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey
*Presenter: dukarnilgun@gmail.com
Abstract
Antibiotics play an important role in biological systems. They are large and natural groups of pharmaceuticals
used in animals and humans for the treatment of
diseases. However, the use of antibiotics may lead to
drug residues and accumulation of antibiotics. The
accumulation of antibiotics in food-producing animals
has become a concern, because of their potential to
cause serious threats to public health. Penicillin G
belongs to the β-lactam group of antibiotics. The
presence of penicillin residues might be responsible for
allergenic reaction in human. Penicillin G residues may
also be responsible for the development of resistant strains of bacteria [1-3].
Electrochemical techniques used in biosensing
technology which are capable of high sensivity, good
stability, low-cost instrumentation and probability for-
on site monitoring have received tremendous attention.
Recently, most common materials used in biosensor
technology are nanaomaterials such as nanoparticles,
carbon nanotubes and graphene. Among these
nanomaterials, carbon nanotubes are of great interest.
Carbon nanotubes have captured the interest of
researches world-wide due to their small size with large surface area, high electrical conductivity, chemical
stability, and mechanical strength. [4].
In this study, we present a multiwalled carbon nanotubes
(MWCNTs) modified disposable screen printed gold
electrode for the detection of Penicillin G. In the first
part of the study, MWCNTs, prepared at different
concentrations, were modified on the disposable gold
electrode surface. The electrochemical behavior of the
electrodes were investigated in 0.1 M KCl solution
containing 5 mM Fe(CN)6 3-/4-
redox probe (Figure 1). Penicillinase enzyme was then immobilized and
amperometric detection of Penicillin G was performed.
Cyclic voltammetric behaviors of the modified
electrodes were also examined. The biosensor
monitored the catalytic hydrolysis of Penicillin G in a
very sensible manner.
Acknowledgments: F. Kuralay acknowledges Turkish
Academy of Sciences (TÜBA) as an associate member
and TÜBA-GEBİP programme.
Figure 1. Cyclic voltammograms of (a) 2.5 mg mL-1
MWCNTs modified electrode, (b) 2.0 mg mL-1 MWCNTs
modified electrode, (c) unmodified electrode, (d) 1.0 mg
mL-1 MWCNTs modified electrode in 0.1 M KCl
containing 5 mM Fe(CN)6 3-/4-.
References [1] P. Thavarungkul, S. Dawan, P. Kanatharana, P.
Asawatreratanaku, Biosensors and Bioelectronics 23
(2007) 688.
[2] Z. Yan, N. Gan, T. Li, Y. Cao, Y. Chen, Biosensors
and Bioelectronics 78 (2016) 51.
[3] L.M. Gonçalves, W.F.A. Callera, M.D.P.T.
Sotomayor, P.R. Bueno, Electrochemistry
Communications 38 (2014) 131.
[4] F. Kuralay, M. Dumangöz, S. Tunç, Talanta 144
(2015) 1133.
Poster Presentation – PP0219
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Gold Nanoparticle-based Colorimetric Assay for Chiral Discrimination of
D-/L-Alanine Enantiomers
Nisa Bekar1*
and Erhan Zor2
1 Department of Chemistry Education, Necmettin Erbakan University, Konya, Turkey
2 Department of Science Education, Necmettin Erbakan University, Konya, Turkey
*Presenter: bekarnisa@gmail.com
4. Introduction
The development of a simple and efficient method for
enantioselective chiral discrimination is tremendously
valuable for drug discovery, pharmaceuticals and
biochemical processes [1]. In recent years, great success
has been attained in chiral discrimination by high-
performance liquid chromatography, gas
chromatography and electrochemical techniques. Apart from the conventional application of these techniques,
one of the most pressing challenges in chiral
discrimination is to achieve rapid and simple visual
discrimination of enantiomers by naked-eye.
Considerable effort has been devoted to the synthesis
and characterization of chiral selective metal
nanoparticles. However, the field of colorimetric chiral
discrimination using metal nanoparticles still remains
unexplored. In recent decades, the use of gold
nanoparticles (AuNPs) as optical label leads to a wide
range of applications in (bio)sensors due to their characteristics such as ease of synthesis and their
intense red color easy to be detected even by naked eye
[2]. Taking advantage of AuNPs, we herein report a
colorimetric assay for chiral discrimination of D/L-
alanine enantiomers. The mechanism is based on the
inherent chirality of citrate-capped gold nanoparticles
that can be used as chiral selector for D- and L-alanine.
2. Experimental
AuNPs were synthesized according to Turkevich
method [3]. Briefly, a sodium citrate solution (1%, 1.25
mL) was rapidly added to a boiled HAuCl4 solution
under vigorous stirring. The mixed solution was boiled
for 10 min while observing the color change from deep
blue to wine-red. The resulting solution was cooled to
room temperature and stored in the refrigerator (4 ˚C).
3. Results and Discussion
Figure 1 shows TEM image of the as-synthesized
spherical AuNPs with the average size 8 nm. Aiming at
examining the chiral recognition ability of the AuNPs D-/L-alanine were added into the AuNPs solution, then
visual and spectroscopic detection was performed.
Figure 2 shows UV-Vis spectra of as-synthesized
AuNPs, D-alanine/AuNPs and L-alanine/AuNPs
solutions. An absorption maximum was observed at 518
nm originating from the surface plasmon absorption of
the dispersed AuNPs. The absorption maximum was
red-shifted in the presence of L-alanine whereas no
change was monitored in the presence of D-alanine.
These results indicate L-alanine could selectively induce
aggregation of AuNPs, but D-alanine shows no effect.
Figure 1 TEM image of the as-synthesized AuNPs
The inset in Figure 2 displays the colorimetric assay of
chiral discrimination in which a well-marked red-to-
blue color change was observed in the presence of L-
alanine, whereas no color change could be observed in
the presence of D-alanine.
Figure 2 Absorption spectra of AuNPs in the presence
of D-alanine, L-alanine. The inset shows the
colorimetric assay photographs
Taking advantage of the inherent chirality of AuNPs,
it can be concluded that the proposed simple sensor can
be used as a convenient colorimetric probe to
discriminate alanine enantiomers, which can be a
promising model for discrimination of other biologically
important enantiomers of chiral molecules.
4. References
[1] Wattanakit et al., Nature Commun., 2014, 3325, 1-8.
[2] Quesada-Gonzalez and Merkoçi, Biosens. Bioelectron., 2015, 73,
47-63.
[3] Turkevich et al., Discuss. Faraday. Soc. 1951, 11, 55–75.
Poster Presentation – PP0220
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Double-Arm Schiff Bases-Tagged Nanomaterial; Synthesis and
Acetylcholinesterase Immobilization
N. Kurnaz Yetim1,2*, E. Hasanoğlu Özkan1, E. Karmaz1 and N. Sari1
1 Department of Chemistry, Gazi University, Ankara, Turkey 1 Department of Chemistry, Kırklareli University, Kırklareli, Turkey
*Presenter: nurdankurnaz81@gmail.com
Introduction
Recently there has been a considerable interest in the
material chemistry of nanoparticules involving metal
ion because of their potential medicine and industrial
applications [1]. The use of nanoparticules in medicine
and more specifically drug delivery is set to spread
rapidly. Nanoparticules involving metal ion play a very
important role not only in chemical reactions
(enzymatic reactions) in the human body but also in
industrial chemical processes [2]. AChE biosensors have been used to detect unknown toxic mixtures, but
there are some problems with the identification of toxic
mixtures in samples. Therefore, new methods are being
investigated by authors. One of these methods is the
immobilization of enzymes onto nanospheres. There has
been an increase in studies on enzyme immobilization
on nanospheres due to their small size and large surface
area.4,5 Nanospheres are useful for improving the
operational stability of immobilization. Therefore
enzyme immobilization into or onto various
nanoparticles has been proposed and reported.
Experimental
To prepared such a support, the N-{2-[Bis(2-
aminoethyl)amino]ethyl}aminomethyl-polystyrene
(2AEPS) reacted with 2-bromo salicylaldehyde by
means of condensation method.
4.1. Immobilization of AChE on nanomaterial
(2AEPS-SalBr)
After dissolving enzyme in pure water (50 mL, 3.6 x 10-
4 gL-1), 2AEPS-SalBr polymer (0.5 g) was placed to a 2
mL of 3.6 x 10-4 gL-1 of AChE. This solution was diluted to 10 ml and at room temperature in a shaking
water bath for 8 h. The immobilized polymer was
separated and the free enzyme was removed by washing
with phosphate buffer and then stored at + 4 °C.
Conclusion
The apparent kinetic parameters of the immobilized
enzyme and free enzyme were compared, and this
showed that the Michaelis constant (Km) of the
immobilized AChE was higher than that of the free
AChE, while there was a significant difference in the
maximum reaction rates (Vmax).
Figure 1 Mechanism for the catalytic activity of AChE
Kinetic parameters were studied for free AChE and
immobilized AChE optimum at pH=8.0 and optimum
temperature (50 oC). Km/Vmax values were calculated
from Lineweaver-Burk plots for immobilized AChE to
the novel support, 1.443 mM and 0.251 mMmin-1
respectively for 50 °C. patterns because they may not be
reproduced properly.
Table 1Kinetic parameters (Km/Vmax; mM/mM min−1)
for free AChE and immobilized AChE
pH Temp.
(°C)
Km/Vmax
(mM/ mM
min−1
)
Free Enzyme 8
50 0.146/1.85
AChE-2AEPS-
SalBr
8 50 1.443/0.251
References
[1] M.C.Daniel, D. Astruc, J. Chem. Rev. 104 (2004) 293.
[2] W.H. De Jong, P.J.A. Borm, Int. J. Nanomed. 3 (2) (2008) 133.
[3] E. Hasanoğlu Özkan, N. Kurnaz Yetim, D. Nartop and N. Sarı, J. Indian Eng. Chem., 25 (2015), 180.
[4] N. Özdem, E. Hasanoğlu Özkan, N. Sarı, F. Arslan and H. Tümtürk, Macromol. Res. 22(12) (2014) 1282.
Poster Presentation – PP0222
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
A Sensitive Electrochemical Biosensor for Determination of Gallic Acid Based on
Polyimide Modified Electrode
Aziz Paşahan1, Nurcan Ayhan1*, İmren Özcan, Serap Titretir Duran1, Süleyman Köytepe1
İnönü University, Faculty of Arts and Science, Chemistry Department, 44280, Malatya, Turkey
*Presenter: nurcan1658hotmail.com
Abstract
Gallic acid (GA), a type of phenolic acid, is occurring in
plants in the form of free acids, esters, and catechin
derivatives[1]. It is commonly used in the
pharmaceutical industry and food industry[2]. Gallic
acid is used as a standard for determining
the phenol content of various analytes. In recent years,
many methods such as chemiluminescence
spectrophotometry and capillary electrophoresis as
well as chromatography were introduced to determinate
of phenolic compounds[3-4]. Electrochemical methods
were used for determination of GA due to low detection
limit, very fast response time, high sensitivity and simplicity[5].
In the present study, a novel polyimide film as selective
membranes was synthesized from 1,5-
diaminonaphthalene and 3,3',4,4'-benzophenonetetra-
carboxylic dianhydride through polycondenzation
reaction and thermal imidization. The prepared
polyimide films were characterized for their structure, morphology, and thermal behavior by Fourier transform
infrared spectroscopy (FTIR), scanning electron
micrograph (SEM), X-ray diffraction (XRD) and
thermal analysis (DTA/TGA/DSC) techniques. The
polyimide membrane was exhibited the highest Tg
because of the rigid heterocyclic unit. The polyimide
were formed by casting the film on the surface of bare
platinum electrodes in one-step procedure. For the
preparation of PI electrode, firstly, a solution of polymer
was made by dissolving about 0,1 g of the obtained dark
amber powdery polyimides in 1 ml of NMP. Then, the
prepared polyimide solution (2 µL) was cast on the surface of bare platinum working electrodes and
polyimide film was dried at room temperature for at
least 2 days.
Differential Pulse Voltammetry (DPV) technique was
used to investigate the electrochemical behavior of the
GA and interference species at modified electrode.
Therefore, it is claimed that the polyimide film can be
used as selective matrix for the rapid and accurate
detection of gallic acid in the presence of various
interferant molecules.
Fig 1. DPV behaviours of 2 mM gallik acid, 2 mM
caffeic acid, 2 mM Ascorbic acid and 2 mM coumaric acid at polyimide modified electrode.
References
[1] M. Naczk, F. Shahidi, J. Pharm. Biomed. Anal. 41
(2006) 1523–1542
[2] S. M. Fiuza, C.Gomes, L.J. Teixeira, MT. Girao da
Cruz, M. N. D. S. Cordeiro, N Milhazes, F.Borges,
M.P.M. Marques, Bioorganic & Medicinal
Chemistry 12 (2004) 3581–3589.
[3] X. Shao, L.S Lv, T. Parks, H. Wu, C.T. Ho, S.M.
Sang, J. Agric. Food Chem. 58 (2010) 12608–
12614.
[4] R.L.C Chen, C.H. Lin, C.Y. Chung, T.J. Cheng, J.
Agric. Food Chem 53 (2005) 8443–8446.
[5] B.B. Petkovic, D. Stankovic M. Milcic, S.P. Sovilj,
D. Manojlovic 132 (2015) 513–519
Poster Presentation – PP0204
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical and nonenzymatic glucose biosensor based on
MDPA/MWNT/PGE nanocomposite
Özge Sürücü1*, Gulcin Bolat1 and Serdar Abaci1
1 Department of Chemistry, Hacettepe University, 06800, Beytepe, Ankara, Turkey
*Presenter: ozge87@hacettepe.edu.tr
1. Introduction
Multi-walled carbon nanotubes (MWNTs) are multiple
layers of graphite superimposed and form a tubular
shape rolling in on themselves. Organic dyes, especially
azo dyes can combine with MWNTs with strong π-π
interactions to form stable hybrids [1]. Electrocatalytic
activity of MWNTs and azo dyes combinations exhibit
excellent properties such as high mechanical stability
and sensitivity for different electrochemical techniques
possessing excellent responses to various substances
such as as redox proteins, drugs, small biomolecules,
hormones, and so on.
A number of studies have been carried out to monitor
blood glucose levels [2]. Among these studies,
electrochemical and optical methods have been
extensively developed to monitor glucose. The
electrochemical and nonenzymatic sensing of glucose is
a cost-effective and rapid approach. Recently, various
nanomaterials have been developed as excellent nanocatalysts to provide new surfaces for fabricating
novel nonenzymatic glucose sensors.
The nonenzymatic sensing of glucose has been widely
investigated in a variety of fields ranging from
biomedical applications to ecological approaches.
Among these fields, electrochemical methods contain
great advantages such as high electrocatalytic ability,
high sensitivity and good selectivity to the electrooxidation of glucose. In this study, the strong
noncovalent adsorption of novel synthesized (E)-4-((5-
methylthiazole-2-yl)diazenyl)-N-phenylaniline (MDPA)
on the surface of MWNT/PGE was performed
electrochemically, and the prepared stable, uniform and
sensitive film (MDPA/MWNT/PGE) was used for
nonenzymatic and direct determination of glucose. The
surface of modified electrodes was characterized using
scanning electron microscopy (SEM) and
electrochemical impedance spectroscopy (EIS)
techniques. The improvement of electrooxidation response of glucose was completed using MDPA/
MWNT/PGE nanocomposite. The effects of scan rate
and pH on the peak potential and peak current of
glucose signal were determined. The limit of detection
and linear range were calculated using various
concentrations of glucose. Interference studies were
performed using coexisting substances including metal
ions such as Al3+, Cu2+, Fe3+ and ascorbic acid to
determine the selectivity of MDPA/MWNT/PGE for
glucose.
2. Results and discussion
Electrocatalytic performance of the modified surfaces
towards the oxidation of glucose was investigated by
SWV between -0.8 V and 0.0 V vs. Ag/AgCl in 0.1 M
NaOH solution containing 5.0 mM glucose. SWVs of
1.0 mg mL-1 MWNT and 1.0 mM MDPA co-deposited
PGE, 1.0 mM MDPA over 1.0 mg mL-1 MWNT
deposited PGE, 1.0 mg mL-1 MWNT over 1.0 mM
MDPA deposited PGE and bare PGE were represented
in Figure 1. Oxidation process of glucose started at -0.8
V following two oxidation peaks at -0.6 V and -0.4 V
vs. Ag/AgCl. The results indicated that the modification improved the electrocatalytic activity towards the
oxidation of glucose. The former peak was oxidation of
glucose to glucolactone and the other was originated
from consequent oxidation of glucolactone [3]. The
main differentation of MDPA over MWNT deposited
PGE (red line) was obtained at -0.6 V vs. Ag/AgCl
observing 5-folds higher current enhancements from
bare PGE (green line) and the proposed surface was
titled as MDPA/MWNT/PGE.
Figure 1. Square wave voltammograms of 1.0 mg mL-1
MWNT and 1.0 mM MDPA co-deposited PGE, 1.0 mM
MDPA over 1.0 mg mL-1 MWNT deposited PGE, 1.0
mg mL-1 MWNT over 1.0 mM MDPA deposited PGE
and bare PGE between -0.8 V and 0.0 V vs. Ag/AgCl in
0.1 M NaOH solution containing 5.0 mM glucose.
References
[1] C. Hu, S. Hu, Journal of Sensors, Volume 2009,
Article ID 187615, 40 pages.
[2] A. Caduff, M. S. Talary, P. Zakharov, Diabetes
Technol. Ther., 2010, 12, 1–9.
[3] L. Larew, D. Johnson, J. Electroanal. Chem., 1989,
262, 167–182.
Poster Presentation – PP0226
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
pH/Redox-Sensitive Hybrid Nanocarriers for Triggered Delivery
R. Tekiner1,2* and G. Birlik Demirel1,2
1Department of Chemistry, Polatli Faculty of Arts and Sciences, Gazi University, Ankara, Turkey 2 Life Sciences Research and Application Center, Gazi University, Ankara, Turkey
*Presenter: refiyetekiner@gazi.edu.tr
Abstract
Cancer remains one of the world’s most devastating
diseases, with more than 10 million new cases
every year[1]. In traditional treatment methods, anti-
cancer drug molecules circulate freely in the blood and
do not exhibit targeted release and kill the healthy cells
besides cancer cells. Because of these reasons and
considering the emerging technology, the scientists
from many disciplines study intensively for the
development of new-generation nanocarrier systems [2,3]. Nanocarriers have many advantages compared to
traditional methods. First of all, the drug molecules are
trapped into the nanocarriers and the toxicity of drug
can be decreased in minimum levels. Thus uncontrolled
delivery can be prevent and the drug dose can be
adjusted to minimum but effective levels. In the light of
the existing information scientists have focused on the
multifunctional and routable nanocarrier systems which
can do selective and controlled release [4-6]. In this
study, we have developed a novel pH/redox-sensitive
hybrid nanocarrier system for controlled drug delivery as seen in Scheme 1.
Scheme 1. Schematic mechanism of the intracellular
pH/redox-controlled release of designed hybrid system
Multifunctional and ellipsoidal hybrid nanoparticles
(Fe3O4@SiO2@PLH-PEG/PEG-FA) composed of an
ellipsoidal Fe3O4 core, a mesoporous silica shell and pH/redox-responsive poly(histidine)-co-poly(ethylene
glycol) (PLH-co-PEG) polymer as gatekeeper and PEG-
Folic acid (PEG-FA) polymer as targeted agent to
obtain an excellent platform for anticancer drug
delivery. In particular, the PLH-co-PEG gatekeeper on
the surface of the hybrid nanoparticle play a key role in
accommodating anticancer drug molecules in the pore
of the silica shell without premature release until
crosslinked polymer shell gatekeepers are cleaved by glutathione (GSH). In addition to PEG-FA polymers
provide to enhance the targeted cellular uptake of the
particles by cancer cells. The experimental results
showed that smart nanoparticles exhibit fast dissociation
in the presence of 10 mM GSH, due to the reductive
cleavage of intermediate disulfide bonds of PLH-PEG
polymer. It can be said that this multifunctional polymer
shell is active for the controlling drug molecules in-and-
out of silica channels. Moreover, the ellipsoidal smart
nanoparticles allowed the perfect release profile under
cellular pH environment. As a result, this study which
involve the experimental and applied research, will help the development of new generation nanocarrier systems.
In our belief, the obtained each result from every step
will be very precious to reach excellent systems in this
field and will provide very big contribute to the
literature.
Acknowledgement: This work was supported by the
TUBITAK Grant No. 115R280.
References
[1] Stewart, B. W., Kleihues, P. 2003. “World cancer
report world health organization press”, Genova, 9-11.
[2] Drbohlavova, J., Chomoucka, J., Adam V.,
Ryvolova, M., Eckschlager, T., Hubalek, J., Kizek, R.
2013. “Nanocarriers for anticancer drugs - new trends in
nanomedicine”, Current Drug Metabolism, 14, 547-564.
[3] Duncan, R. 2006. “Polymer conjugates as anticancer nanomedicines”, Nat. Rev. Cancer, 6, 688–701
[4] Cho, K. J., Wang, X., Nie, S. M., Chen, Z., Shin, D.
M. 2008. “Therapeutic nanoparticles for drug delivery
in cancer”, Clin. Cancer Res., 14, 1310-1316.
[5] Mishra, B., Patel, B. B., Tiwari, S. 2010. “Colloidal
nanocarriers: a review on formulation technology, types
and applications toward targeted drug delivery”,
Nanomed.-Nanotechnol. Biol. Med., 6, 9-24.
[6] Peer, D., Karp, J. M., Hong, S., FaroKhzad, O. C.,
Margalit, R., Langer, R. 2007. “Nanocarriers as an
emerging platform for cancer therapy”, Nat. Nanotechnol., 2, 751-760.
Poster Presentation – PP0228
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation of a Biosensor for Determination of Choline
R. Baskın1*, E. (Aynacı) Koyuncu1, H. Arslan2 and F. Arslan2
1Department of Chemistry, Institute of Sciences, Gazi University, Ankara, Turkey
2Department of Chemistry, Faculty of Science, Gazi University, Ankara, Turkey
*Presenter: ruyabaskin@gmail.com
1.Introduction
Choline is an amino alcohol and a component of
lecitines [1,2]. It has many important biochemical roles.
It is one of the fundamental components of cell
membranes, a major component of phospholipids
(phosphatidylcholine) [3]. Furthermore, choline is the
precursor molecule for significant neurotransmitter
acetylcholine in both peripheral and central nervous
system of mammals [4,5]. So, choline detection and
determination is very important for clinical analyses. In
this study, we report a new choline oxidase (ChO) and Toluidine Blue O (TBO) based amperometric choline
biosensor for the determination of choline.
5. Materials and Methods
In this study, an amperometric choline biosensor with
immobilization of TBO (as a mediator,), ChO onto
polypyrrole-polyvinylsulphonate (PPy-PVS) film was
accomplished on the surface of a platinum electrode.
ChO and TBO were immobilized by a
glutaraldehyde/bovine serum albumin crosslinking
procedure onto PPy-PVS film after the
electropolymerization process. The effects of substrate concentration, pH and temperature on the response of
the choline biosensor were investigated. The operational
and storage stability of the biosensor were also studied.
The amperometric response was based on the
electrocatalytic properties of TBO. The changes in the
anodic current at -0.23 V vs Ag/AgCl produced by TBO
was proportional to the choline concentration changes in
sample (Figure 1).
6. Results and Discussion
In this study, a novel amperometric choline biosensor
with ChO, and TBO onto PPy-PVS film was
accomplished. The optimum working conditions with
respect to the substrate concentrations were
investigated. The effects of pH and temperature were
investigated and optimum parameters were found to be
7.0 and 30.0 ˚C, respectively. The storage stability and
operational stability of the enzyme electrode were also
studied and linear range was determined. Interfering
effect of some common substances was investigated.
The experimental results clearly showed that the choline
biosensor was sensitive and selective and its operational
stability and long-term storage stability were found to
be good. This biosensor was also easy to prepare and
was highly cost effective.
Figure 1 Reaction scheme for the detection of choline
7. References
[1] Özdemir, M., Arslan, F. and Arslan, H. (2012). An
amperometric biosensor for choline determination
prepared from choline oxidase immobilized in
polypyrrole-polyvinylsulfonate film. Artificial Cells,
Blood Substitutes, and Biotechnology, 40, 280-284.
[2] Langer, J.J., Filipiak, M., Kęçińska J., Jasnowska, J.,
Włodarczak, J. and Buładowski, B. (2004). Polyaniline
biosensor for choline determination. Surface Science, 573, 140-145.
[3] Galban, J., Sanchez-Monreal, O., Andreu, Y., de
Marcos, S, and Castillo, J.R. (2004). Choline
determination based on the intrinsic and the extrinsic
(chemically modified) fluorescence of choline oxidase.
Analytical Biochemistry, 334, 207-215.
[4] Aynacı, E., Yaşar, A. and Arslan, F. (2014). An
amperometric biosensor for acetylcholine determination
prepared from acetylcholinesterase-choline oxidase
immobilized in polypyrrole-polyvinylsulpfonate film.
Sensors and Actuators B: Chemical, 202, 1028-1036. [5] Garguilo, M.G. and Micheal, A.C. (1995).
Optimization of amperometric microsensors for
monitoring choline in the extracellular fluid of brain
tissue, Analytica Chimica Acta, 307, 291-299.
Poster Presentation – PP0229
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Ascorbic acid, dopamine and uric acid determination using a novel, highly
selective and sensitive rGO/PPy-Pt sensor
Fatih Sen1, Sait Bozkurt1* and Ceyda Uluturk1
1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupinar University, Kütahya,
Turkey
*Presenter: saitbozkurt91@gmail.com
Abstract
We report here an efficient and simple approach for the
preparation of a partially reduced graphene oxide
polypyrrole zinc oxide modified glassy carbon electrode
(RGO-Ppy-Pt/GCE). The modification of the RGO-
GCE consists of three steps. These include (i) chemical
synthesis of graphite oxide by a modified Hummer's method,1 (ii) exfoliation of graphite oxide to graphene
oxide (GO) by ultra-sonication and (iii) controlled
partial electrochemical reduction in 0.1 M phosphate
buffered medium (pH 3.0) via potentiodynamic cycling
(2 cycles) to obtain a partially reduced graphene oxide
modified glassy carbon electrodes (RGO-GCE). The
behaviour of the RGO-GCE towards ascorbic acid
(AA), dopamine (DA) and uric acid (UA) was
investigated by differential pulse voltammetry, with an
enrichment time of 3 minutes.2-3 Morphological (SEM
and TEM) and electrochemical characterization studies
were also reported. Finally, the performance of the RGO-GCE based sensor was successfully tested for
analysing UA and quantitative recoveries of AA and DA
in serum samples.
Figure: (a) DPV results of AA, DA and UA at GCE,
rGO/PPy-Pt modified electrodes
References
[1] O. Arrigoni and M. C. D. Tullio, Biochim. Biophys.
Acta, 2002, 1569, 1.
[2] J. H. Kim, J. M. Auerbach, J. A. R. Gomez, I.
Velasco, D. Gavin, N. Lumelsky, S. H. Lee, J. Nguyen,
R. S. Pernaute, K. Bankiewicz and R. McKay, Nature,
2002, 418, 50.
[3] V. S. E. Dutt and H. A. Mottola, Anal. Chem., 1974,
46, 1777.
Poster Presentation – PP0230
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
-0,2 0,0 0,2 0,4 0,6 0,8
-120,0µ
-60,0µ
0,0
60,0µ
120,0µ
180,0µ
240,0µ
300,0µ
360,0µ
420,0µ
AAI/A
E/V
Forward scan
DA
UA
Increase in scan no.
Incorporating PPy with ZnO Nanorods on Rgo: A Potentiometric Strategy for
Selectivity and Detection of Dopamine, ascorbic and uric acid
Fatih Sen1, Sait Bozkurt
1* and Ceyda Uluturk
1
1Sen Research Group, Department of Biochemistry, Faculty of Arts and Science, Dumlupinar University.
*Presenter: saitbozkurt91@gmail.com
Abstract
In this study, the investigation regarding the fabrication
of a reduced graphene oxide-polypyrole-platin
(rGO/PPy-ZnO) was carried out. The reduced graphene
oxide modified glassy carbon electrodes (rGO/PPy-
ZnO) were obtained by following procedure; graphite
oxide production, graphene oxide synthesis and finally, rGO/PPy-ZnO fabrication; chemical synthesis, ultra-
sonication and electrochemical reduction via
potentiodynamic cycling were used, respectively. The
differential pulse voltammetry (DPV) was utilized to
check rGO/PPy-ZnO performance against ascorbic acid
(AA), dopamine (DA) and uric acid (UA). At pH 3.0,
as-prepared electrode exhibits high sensitivity and give
precise and separate data for AA, DA and UA, they can
be examined separately and instantly. With 1x10-6 to
1,5x10-5 M detection limit, the series of the amounts of
2x10-1 M AA, 2x10-1 M DA and 1x10-1 to 2x10-1 M UA
were determined as the sensing intervals for as-prepared electrode. The as-obtained electrode was characterized
by morphologically and electrochemically. At the end,
for the analytical determination of UA and for
discovering the amount of AA and DA in serum
specimen, the rGO/PPy-ZnO was used [1-3].
Figure: (a) CV results of AA, DA and UA (each 1 x 10-3
M, scan rate 50 mV s-1) at GCE, rGO/PPy-ZnO
modified electrodes.
References
[1] O. Arrigoni and M. C. D. Tullio, Biochim. Biophys.
Acta, 2002, 1569, 1.
[2] J. H. Kim, J. M. Auerbach, J. A. R. Gomez, I. Velasco, D. Gavin, N. Lumelsky, S. H. Lee, J. Nguyen,
R. S. Pernaute, K. Bankiewicz and R. McKay, Nature,
2002, 418, 50.
[3] V. S. E. Dutt and H. A. Mottola, Anal. Chem., 1974,
46, 1777.
Poster Presentation – PP0231
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Nanomaterials-based DNA Damage Detection
Selma Tunc1* and Filiz Kuralay1
1Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey
*Presenter: selma_tnc@hotmail.com
Abstract
Deoxyribonucleic acid (DNA) is the largest, well-
defined and also the most important molecule of life.
DNA plays an important role in the life process since it
carries heritage information and instructs the biological
synthesis of proteins and enzymes through the process
of replication and transcription of genetic information in
living cells [1-3].
Damage to DNA may result in critical disturbances in
the cell life. As a result of the damage, serious impacts
on human’s health can occur. DNA damage can lead to diseases such as Alzheimer, Parkinson’s disease and
cancer [4,5]. Thus, there is a considerable interest in the
development of highly sensitive and accurate sensing
platforms for the detection of DNA damage. Different
detection techniques have been employed responding to
DNA damage, including fluorescence, surface plasmon
resonance, quartz crystal microbalance and
electrochemistry.
Electrochemical techniques are well suited for rapid and
direct detection of DNA damage since DNA bases are electroactive. Furthermore, electrochemistry have
attracted great attention for the construction of sensitive,
selective, low-cost, rapid and simple sensing platforms.
Electrochemical biosensors can be operated in turbid
media, have comparable instrumental sensitivity and are
more amenable to miniaturization [6,7].
In this study, we present a graphene modified disposable
pencil graphite electrode (GN/PGE) for the detection of
DNA damage. DNA damage was investigated in the
presence and absence of Fenton reagents (Fe2+/H2O2) according to the changes in the oxidation signals of
DNA bases (Guanine, Adenine, Thymine, Cytosine). In
the first part of the study, we synthesized graphene
according to the modified Hummers’s method and
modified the synthesized graphene onto the graphite
electrode surface [8]. Unmodifed PGE and GN/PGE
were characterized by scanning electron microscopy
(SEM) (Figure 1) and cyclic voltammetry (CV). Then,
DNA damage was performed using Fenton reagents.
Electrochemical detection of the damage was carried
out with differential pulse voltammetry (DPV).
Improved electrochemical responses were obtained with the nanomaterials-based electrode compared to the
unmodified (bare) electrode. Well-defined oxidation
signals of DNA bases were observed using graphene
modified disposable graphite electrode, which later on
provided a better sensing platform for monitoring the
changes in the oxidation signals of DNA bases after the
damage.
Figure 1 SEM images of (a) unmodified PGE, (b)
GN/PGE
Acknowledgments: This work has been supported by L’Oréal-UNESCO For Women in Science Programme.
F. Kuralay acknowledges Turkish Academy of Sciences
(TÜBA) as an associate member and TÜBA-GEBİP
programme.
References [1] E. Palecek, Talanta 56 (2002) 809.
[2] F. Kuralay, S. Campuzano, J. Wang, Talanta 99
(2012) 155.
[3] F. Kuralay, A. Erdem, S. Abacı, H. Özyörük, A. [1]
Yıldız, Electrochem. Commun. 11 (6) 1242.
[4] M. Fojta, Electroanalysis 14 (2002) 1449. [5] E. Palecek, M. Fojta, Anal. Chem. 73 (2001) 74A.
[6] V. Ostatna, F. Kuralay, L. Trnkova, E. Paleček,
Electroanalysis 20 (13) 1406.
[7] F. Kuralay, A. Erdem, Analyst 140 (8) 2876.
[8] M. Zhou, Y. Zhai, S. Dong, Anal. Chem. 81 (2009)
5603.
Poster Presentation – PP0233
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Investigation of the Effect of Antioxidants on DNA
Damage
Selma Tunc1* and Filiz Kuralay1
1Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey
*Presenter: selma_tnc@hotmail.com
Abstract Antioxidants are molecules that inhibit the oxidation of
other molecules. Chemical reactions-based on oxidation
can produce free radicals, leading to chain reactions that
may damage cells. It is well-known that antioxidants
such as glutathione, catalase, melatonin, uric acid,
Vitamin A, Vitamin C (ascorbic acid) (Figure 1) and
Vitamin E terminate these chain reactions [1,2].
The reactive oxygen species produced in cells include
hydrogen peroxide (H2O2) and free radicals such as the
hydroxyl radical (·OH) and the superoxide anion (O2−).
The hydroxyl radical is particularly unstable and reacts
rapidly and non-specifically with most biological
molecules. This species is produced from hydrogen
peroxide in metal-catalyzed redox reactions such as
the Fenton reaction. These oxidants can damage cells by
starting chemical chain reactions such as by oxidizing
DNA [3-5]. This damage to DNA can
cause mutations and possibly cancer, if not reversed
by DNA repair mechanisms. Researches have been
presented that antioxidant molecules can inhibit this
DNA damage [6].
In the present work, we investigate the effect of ascorbic
acid, glutathione and uric acid on the DNA damage
produced by Fenton reagents (Fe2+/H2O2). A graphene
modified disposable pencil graphite electrode
(GN/PGE) was used for the construction of the
biosensing platform for the investigation of the effect of
antioxidants on DNA damage. Graphene is a two-
dimensional (2D) carbon-based nanomaterial (sp2
hybridized carbon) which has unique properties such as
good thermal, electrical, optical and mechanical
properties, having high specific surface area and ultrahigh carrier mobility [7]. The invention of graphene
has been one of the milestones in nanotechnology. It has
been a great potential for various researches such as
electrochromic devices, lithium batteries,
supercapacitors, solar cells and (bio)sensing devices.
Thus, in the current study, graphene provided a
convenient interface on the graphite electrode by
enhancing the electrochemical properties of the sensing
surface, including good electrical conductivity, high
electroactive surface area and high mobility transport
performance.
Electrochemical detection of the effect of antioxidants
was carried out with differential pulse voltammetry
(DPV) using different concentrations of ascorbic acid,
glutathione and uric acid. The effect of different
interaction times were also examined in the study. It was
found that these molecules had the ability to inhibit the DNA damage.
Figure 1 Chemical structure of Vitamin C (ascorbic
acid)
Acknowledgements: This work has been supported by
L’Oréal-UNESCO For Women in Science Programme.
F. Kuralay acknowledges Turkish Academy of Sciences
(TÜBA) as an associate member and TÜBA-GEBİP
programme.
References [1] J. Labuda, M. Buckova, L. Heilerova, S. Silhar, I.
Stepanek, Anal. Bioanal. Chem. 376 (2003) 168.
[2] O. Korbut, M. Buckova, J. Labuda, P. Grundler,
Sensors 3 (2003) 1.
[3] A. Sancar, Chem. Rev. 103 (2003) 2203.
[4] K. Cahova-Kuchaříkova , M. Fojta ,T. Mozga, E. [1]
Palecek, Anal. Chem. 77 (2005) 2920.
[5] M. Fojta, Electroanalysis 14 (2002) 1449.
[6] Y. Yang, J. Zhou, H. Zhang, P Gai, X. Zhang, J.
Chen, Talanta 106 (2013) 206. [7] J. Wang, Analyst 130 (2005) 421.
Poster Presentation – PP0234
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Plasma Enhanced Preparation of Graphene/Polyfuran Nanocomposites
Gamze Celik Cogal1,2, Sadik Cogal2, Filiz Kuralay3, Selma Tunc3*, Maria Omastova4, Matej Micusik4, Lutfi Oksuz5 and
Aysegul Uygun Oksuz1
1Department of Chemistry, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey
2Department of Polymer Engineering, Mehmet Akif Ersoy University, 15030 Burdur, Turkey 3Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey
4Polymer Institute, Dúbravska cesta 9, 845 41 Bratislava, Slovakia 5Department of Physics, Faculty of Arts and Sciences, Suleyman Demirel University, 32260 Isparta, Turkey
*Presenter: selma_tnc@hotmail.com
Abstract
Graphene is a 2D structure of carbon, which composed
of sp2-bonded single-layer carbon atoms with
honeycomb lattice. In the recent years, graphene has
received increasing attention due to its unique electrical,
optical, mechanical and termal and chemical stability
properties [1].
(a) (b)
Figure 1 Molecular structure of graphene (a) and
polyfuran (b)
Conducting polymers (CP) have also attracted
significant importance in different areas due to their ability to prepare polymer materials with similar
electrical and optical properties to semiconductors or
even metals. Among CPs, polyfuran is interesting
because of its possible technological applications such
as sensors and optoelectronic devices [2]. However, it
has been less studied due to difficulty of synthesis.
Although CPs exhibit excellent properties, some
properties such as electrical conductivity are not
sufficient for some applications and need to be
developed. One approach is combining the CPs with
graphene. The combination of the excellent properties of GR and conducting polymers in composite structures
enhanced the electrical conduction and electrocatalytic
activity of CPs.
In this study, graphene/polyfuran nanocomposites and
polyfuran homopolymers were synthesized using RF-
rotating plasma (Fig. 2) [3], which is fast, versatile and
environmentally friendly process. During the
experiment the plasma chamber was rotated under
constant rate for obtaining uniform coating of polyfuran
on the surface of graphene. The collected graphene coated with polyfuran was directly characterized
without further treatment.
Figure 2 RF-rotating plasma system used for
preparation of composites
The prepared materials were characterized by using
fourier transform-infrared spectroscopy (FT-IR),
scanning electron microscopy (SEM), thermal
gravimetric analysis (TGA) and electrochemical measurement.
Acknowledgements: This work has been supported by
TUBITAK-114M877 project.
References [1] Z. Yin, J. Zhu, Q. He, X. Cao, C. Tan, H. Chen, Q.
Yan, H. Zhang, Graphene-based materials for solar cell
applications, Adv. Energy Mater., 4 (2014) 1300574.
[2] M. Ates, A review study of (bio)sensor systems
based on conducting polymers, Materials Science and Engineering C, 33 (2013) 1853.
[3] A. Uygun, L. Oksuz, A.G. Yavuz, A. Guleç, S. Sen,
Curr. Appl. Phys., 11 (2011) 250.
Poster Presentation – PP0235
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Behavior of Cefuroxime Axetil
on Graphene Oxide Modified Glassy Carbon Electrode
S.Erdoğan Kablan1* and N. Özaltın1
1Department of Analytical Chemisty, Hacettepe University, Faculty of Pharmacy
*Presenter: sevilay.erdogan@hacettepe.edu.tr
Abstract The electrochemical oxidation behavior of Cefuroxime Axetil
(CEFA) on graphene oxide modified GCE was investigated by voltammetric methods in pH 2 Britton-Robinson buffer. A well-defined peak was observed at 1.30 V vs. Ag/AgCl for electrooxidation of CEFA at modified glassy carbon electrode (M-GCE) by using square wave voltammetry (SWV). Current type, reversibility of electrode reaction and the number of electrons transfered were investigated by using cyclic voltammetry (CV), chronoamperometry (CA) and chronocoulometry (CC). Besides the calculation of diffusion
coefficient and rate constant of electron transfer, the oxidation mechanism was also proposed.
1.Introduction
Cephalosporins are derived from Cephalosporium which is species of mushroom. They are antibiotics with a broad spectrum of antimicrobial and antibacterial properties and classified into four generations. CEFA is a second-generation cephalosporin and an oral prodrug formulation of the
injectable antibiotic cefuroxime (CEF). Chemical structure of CEFA is shown in Fig. 1. CEFA is the 1-acetoxyethyl ester of CEF. This ester product increases the lipophilicity and the oral bioavailability of the parent compound [1].
Figure 1. Chemical Structure of CEFA
There has not been a method described for the electrochemical
behaviors of CEFA using bare glassy carbon electrode (GCE) and graphene oxide modified glassy carbon electrode (M-GCE). Therefore, the aim of this work was to investigate the electrochemical behaviors of CEFA at M-GCE, and to propose the oxidation mechanism, by using SWV, CV, CA, and CC methods. Graphene/graphene oxide has gained technological importance in several years [2]. The oxidation peak current of
CEFA on bare GCE was too low for investigation (Fig.2). Thats why it has been decided to modify the GCE electrode with graphene oxide to increase the peak current. In this study the peak current (Ip) enhanced for 7-fold, compared to that bared GCE, in the presence of graphene oxide due to the increased surface area and improved electrical conductivity that occured by using graphene oxide modified GCE (Fig.2).
Figure 2. The Effect of Graphene Oxide Amount on Peak Current of 38.0 mg L-1 CEFA in Modification Process
There is no cathodic peak on the cyclic voltammogram of CEFA and the peak potential shifted to positive values with increasing scan rate, so CEFA oxidation is irreversible on M-GCE (Fig. 3). The Slope of (log Ip) vs (log v) graph was obtained 0.1396, which is lower than 0.50 indicates that oxidation current of CEFA was diffusion controlled. Because of the thin film on modified electrodes, the slope of (log Ip) vs (log v) decreases from 0.5 to lower values [3].
Figure 3. Cyclic Voltammograms of 16.13 µg mL-1 CEFA at different scan rates a) Supporting Electrolyte b)25 c)50 d)75 e)100 f)250 g)500 mV s-1
References
[1] A. Finn, A. Straughn, M. Meyer, J. Chubb, Effect of dose and food on the bioavailability of cefuroxime axetil, Biopharmaceutics & drug disposition 8 (1987) 519-526. [2] M. Pumera, Electrochemistry of graphene: new horizons for sensing and energy storage, The Chemical Record 9 (2009) 211-223. [3] M. Vilas-Boas, C. Freire, B. De Castro, A. Hillman, Electrochemical Characterization of a Novel Salen-Type
Modified Electrode, The Journal of Physical Chemistry B 102 (1998) 8533-8540.
Poster Presentation – PP0236
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Studies on the Anti-Parkinson Drug Pramipexole:Square Wave
Voltammetric Determination on Graphene Oxide Modified Pencil Graphite
Electrode and Investigation of Drug-DNA Interaction
Sevilay Erdoğan Kablan1* and Ceren Yardımcı1
1Department of Analytical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
*Presenter: sevilay.erdogan@hacettepe.edu.tr
1. Introduction
Pramipexole is an orally active non-ergoline dopamine
agonist with selective activity at dopamine receptors
belonging to the D2 receptor subfamily (D2, D3, D4
receptor subtypes) and with preferential affinity for the
D3 receptor subtype. It is approved as monotherapy in
early Parkinson’s disease and as adjunctive therapy to
levodopa in patients with advanced disease experiencing
motor effects because of diminished response to
levodopa [1].
The widespread use of pramipexole and the need for
clinical and pharmacological study require fast and
sensitive analytical techniques to assay the presence of
the drug in pharmaceutical dosage forms and also in
biological samples. Electroanalytical methods have
proved to be useful for development of very sensitive
and selective methods for the determination of organic
molecules, including drugs and related molecules in
dosage forms and biological fluids.
The interaction of DNA with drugs is an important issue
in life sciences. The investigation based on DNA
interactions has great importance in understanding the
mechanism of action of many drug compounds,
designing of new DNA-drug biosensors and screening
of the drugs in vitro. Electrochemical DNA biosensors
enable the study of the interaction of DNA immobilized
on the electrode surface with analytes in solution.
In this study, the voltammetric behavior of pramipexole
at a graphene oxide modified pencil graphite electrode
and at a DNA biosensor is presented.
2. Method
The electrochemical behavior of pramipexole was
studied over a wide pH range (3.0–10.0) at graphene
oxide modified pencil graphite electrode using cyclic
and square wave voltammetry. The best definition of the
analytical signals was found in Britton Robinson buffer
(pH 4.0) at 0.8 V (versus Ag/ AgCl).
The peak current obtained in square wave voltammetry
is dependent on various instrumental parameters. The
optimized parameters can be summarized as follows:
frequency 40 Hz, amplitude 5 mV and pulse size 50
mV.
For investigating the interaction between DNA and pramipexole, differential pulse voltammetry and
guanine oxidation signal monitoring before and after
interaction between drug and DNA is used. The DNA
was immobilized on a pretreated pencil graphite
electrode by applying a potential at +0.5 V in 0.5 M
acetate buffer solution containing 0.02 M NaCl. The DNA modified pencil graphite electrode was immersed
in the blank 0.5 M acetate buffer (pH 4.8) containing
0.02 M NaCl and the oxidation signals of guanine were
recorded using differential pulse voltammetry. The
procedure was repeated using a new pencil graphite
electrode, the electrochemical response of pramipexole
was investigated using bare and DNA attached pencil
graphite electrode.
3. Results and Discussion
In this work, we combined the advantages of disposable
pencil graphite electrode and unique physicochemical
properties of graphene oxide. The relationship between
oxidation peak current and concentration of
pramipexole was linear. Validation parameters such as
sensitivity, accuracy, precision, and recovery were evaluated. The proposed method was employed for
quantification of pramipexole in different
pharmaceutical formulations. In addition, the DNA
modified pencil graphite electrode was used in
combination with differential pulse voltammetry to
obtain the information about the interaction between
DNA and pramipexole.
References
[1] M. Dooley, A. Markham, Drugs & Aging, 12 (1998)
495-514.
Poster Presentation – PP0237
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Catechol determination using a novel electrochemical nanobiosensor
S.Kurbanoglu1, 2*, Lourdes Rivas2, Sibel A. Ozkan1 and Arben Merkoçi2, 3
1Ankara University, Faculty of Pharmacy, Department of Analytical Chemistry, Ankara, TURKEY 2Nanobioelectronics & Biosensors Group, ICN2- Institut Catala de Nanociencia i Nanotecnologia, Campus
UAB, 08193 Bellaterra, Barcelona, Spain, 3ICREA, Barcelona, Catalonia, Spain
*Presenter: skurbanoglu@gmail.com
1. Introduction
Biosensors have great potential for achieving detect-to-
protect devices: devices that can be used in detections of
pollutants and other threating compounds/analytes
protecting citizens’ life [1].
Enzymes have high affinities toward corresponding
substrates being able to catalyze several biochemical
reactions without being permanently changed. The
recognition system of a biosensor directly depends on
the enzyme-substrate relation, which is measured by the transducer onto which surface enzymes are immobilized
[2].
Use of nanomaterials offers to biosensing platforms
exceptional optical, electronic and magnetic properties.
Nanomaterials can increase the surface of the
transducing area of the sensors that in turn increases
catalytic behaviors [3].
2. Experimental
Tyrosinase (Tyr) from mushroom (Z1000 unit/mg),
catechol was purchased from Sigma-Aldrich (St. Louis,
MO). As the electrochemical detector, screen printed carbon electrodes (SPEs) consisted of a set of three
electrodes: carbon working electrode with a diameter of
3 mm, Ag/AgCl pseudo reference electrode (with a
potential of 10 mV with respect to a commercial
Ag/AgCl electrode) and carbon counter electrode with
an approximate thickness of 4 μm were used.
In this study, a novel biosensing platform, for the
determination of catechol was designed, using carbon
nanotubes (CNTs), polythionine (pThi), Iridium oxide
nanoparticles (IrOx NPs) and tyrosinase.
3. Results In order to immobilize Tyr, firstly carbon nanotubes are
dropped on the surface of the screen printed electrodes.
0.5 mM Thionine was polymerized on the surface of
SPE/CNT between -0.4 V and 0.4 V with 50 mV/s scan
rate for 20 cycles in 0.1 M phosphate buffer. 0.25 %, 5
µL glutaraldehyde, 5 µL IrOx NPs and Tyrosinase were
added to immobilize tyrosinase.
To optimize the amperometric catechol response
different number of scans (5-30 CVs), different amount
of IrOx NPs (1-7 µL) and Tyr (2-10 µL) were studied.
Scanning Electron Images were obtained to follow the
surface changes by carbon nanotubes polythionine, Iridium oxide nanoparticles and tyrosinase (Figure 1).
Chronoamperometric responses of SPE modified with
SPE/CNT/pThi/IrOx/Tyr for continuous additions of 0.2
µM catechol while applying a -200mV potential.
Figure 1. SEM images of the designed biosensor. Scale
bars of SEM images are 200 nm. The SEM images were
obtained using backscatter electrons (BE) mode (right
column) and secondary electron (SE) mode (left
column).
The analytical characterization of the
SPE/CNT/pThi/IrOx/Tyr evaluated by continuous
additions of catechol at different concentrations. A
linear response for catechol with r= 0.99 0.2 to 48 µM
was observed. Within 10 s after each addition of
catechol, sensitive bioelectrocatalytic response reaches
about 95% of the steady-state current. Limit of detection
(LOD) and limit of quantitation (LOQ) values of the
developed biosensor were calculated according to the
3s/m and 10s/m criteria, respectively, where ‘s’ is the
standard deviation of the peak currents of low concentration of the analyte and ‘m’ is the slope of the
related calibration graph. LOD and LOQ values are also
calculated as 0.08 and 0.2 µM catechol, respectively.
Relative standard deviation (RSD) values were lower
than 15% for between day repeatability and lower than
10% for within-day repeatability [4].
References
[1] Thévenot, D. R., Toth, K., Durst, R. A., Wilson, G. S. (2001). Electrochemical biosensors: recommended definitions and classification. Biosensors and Bioelectronics, 16(1), 121-131. [2] Datta, S., Christena, L. R., Rajaram, Y. R. S. (2013). Enzyme immobilization: an overview on techniques and
support materials. 3 Biotech,3(1), 1-9. [3] Marín, S., Merkoci, A., Nanomaterials Based Electrochemical Sensing Applications for Safety and Security Electroanalysis 2012, 24, No. 3, 459 – 469 [4] S.A. Ozkan, “Electroanalytical methods in pharmaceutical analysis and their validation”, HNB Pub., New York, 2011.
Poster Presentation – PP0238
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Protein Adsorption and Real Time Cell Analysis of SAM Modified Au Surfaces
S. Eren1*, D. Hür2, L. Uzun3, B. Garipcan1 and Filiz Kuralay4
1 Institute of Biomedical Engineering, Boğaziçi University,
2 Department of Chemistry, Anadolu University, 3Department of Physics, Chemistry, and Biology, Linköping University
4Department of Chemistry, Ordu University
*Presenter: sezin.eren@boun.edu.tr
1. Introduction
Cell-surface interaction is one of the important topics that attract attention of researches to investigate effect of surface properties on cell behavior. Surface properties, such as wettability, chemistry, topography and stiffness have effect on cell adhesion. However, it should be considered that protein adsorption is occurred before cell adhesion. Due to this reason, protein adsorption has a key role that affects cell adhesion indirectly [1-3]. In this study, according to these
knowledge, protein adsorption and cell studies were run via Quartz Crystal Microbalance (QCM) biosensor and real time cell analyzer (RCTA) to observe effect of surface modifications on protein adsorption and cell adhesion.
2. Materials and Methods
In this study, novel amino acid (histidine, leucine, serine, and tryptophan) conjugated SAMs were synthesized in our laboratory, which have special affinity to Au surfaces and attracted by chemisorption [4].
Substrates were modified in-situ in flow cell during QCM (SRS, CA, USA) frequency measurement. 10mM SAM
solutions were used for modifications. In addition, water contact angle and XPS analysis were done to prove modifications.
Protein adsorption experiments were run after surface modifications with human albumin, fibrinogen for human plasma, and immunoglobulin G via QCM system with different concentrations.
xCellgance (ACEA Bioscienses, Boston, USA, kindly supplied by ELIPS, Turkey) was used for real time cell analysis. Before cell analysis, the Au electrodes of the system were modified with SAMs immersing method, and then cell analysis experiment was conducted for 48 hours with osteoblast cells. During experiment, cell culture medium and the application of a low voltage create an electric field between the electrodes, which is called cell index [6].
3. Results and Discussions
Proteins have significant role in determining the biocompatibility and cell adhesion according to amount, interaction strength, and conformation [5]. Aim of protein adsorption investigation part was manipulation of the protein adsorption by surface modifications. The surface modifications were proved by QCM frequency measurement,
water contact angle measurement, and XPS analysis before protein adsorption investigations.
According to results of the protein adsorption study,
fibrinogen has shown the highest affinity to Leu-SAM. In addition, Leu-SAM has highest affinity for all proteins than the other SAMs.
The cell index results of RCTA showed that Ser-SAM
modified surfaces have higher viability for cells than Leu-SAM modified surface. Leu-SAM modified surfaces have shown less effect on cell viability as a result of comparison with control group.
Figure 1 Osteoblast cells and Ser-SAM, Leu-SAM modified surfaces interaction real time analysis ,incubated at 37°C, 5% CO2 for 48 hours
References
[1] T. Jacobs, R. Morent, N. de Geyter, P. Dubruel, C. Leys, “Plasma surface modification of biomedical polymers:Influence of cell-material interaction”, Plasma Chem Plasma Process, 32, 1039-1073, 2012 [2] E. Psarra, U. König, Y. Ueda, C. Bellmann, A. Janke, E. Bittrich, KJ. Eichorn, P. Uhlmann, “Nanostructured
Biointerfaces: Nano-architectonics of Thermoresponsive Polymer Brushes Impact Protein Adsorption and Cell Adhesion”, ACS Appl Mater Interfaces, 17, 12516-29, 2015 [3] S. Hong, “Quantitative Analysis of Cell-Surface Interactions and Cell Adhesion Process in Real-time”, Phd. Thesis, Drexel University, 2008 [4] C.K. Akkan, D. Hür, L. Uzun, B. Garipcan, “Amino Acid Conjugated Self Assembling Molecules for Enhancing Surface
Wettability of Fiber Laser Treated Titanium Surfaces”, Applied Surface Science, 366, [5] C. Fornaguera, G. Caldero, M. Mitjans M.P. Vinardell, C. Solans, C. Vauthier, ”Interactions of PLGA nanoparticles with blood components: protein adsorption, coagulation, activation of the complement system and hemolysis studies” Nanoscale, 7, 6045-58, 2015 [6] J.M. Serra, “xCELLigence system for real-time label-free
monitoring of growth and viability of cell lines from hematological malignancies”, Onco Targets Ther, 7,985-994, 2014
Poster Presentation – PP0239
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation of Poly(thionine) Supported Palladium Nanoparticles For
Biosensing Applications
S. Kırlak* and M. Sönmez Çelebi
Department of Chemistry, Faculty of Science and Arts, University of Ordu, 52200, Ordu, Turkey
*Presenter: songulkirlak@hotmail.com
1. Introduction
Conducting polymers have been widely studied due to their
potential applicability in fields like catalysis, electronic devices and sensor and biosensors design. Their ability to enhance electron transfer along with good sensitivity and versatility has attracted much interest in the use of conducting polymer films, namely polypyrrole, polythiophene and polyaniline, as suitable matrices for biomolecules immobilisation. For this purpose, the presence of free functional groups, appropriate for the interaction with biomolecules, provide further advantage [1].
Thionine (TH) is a phenothiazine redox dye which can be easily dissolved in water and ethanol. The chemical structure
of TH is a small planar molecule with two –NH2 groups symmetrically distributed on each side. Both thionine monomer and the electrogenerated poly-thionine (PTH) have excellent electrocatalytic activity toward the redox of small molecular compounds. Thionine has been used in many sensor applications [2].
Metal nanoparticles are objects of great interest in modern chemistry and materials research possessing physical as well as chemical properties, which are distinct both from the bulk phase and from isolated atoms and molecules. Metal nanoparticles supported on functional materials have many
advantages over unsupported nanoparticles. In connection with metal nanoparticles as the catalytically active moieties, the use of functional polymers offers some features, namely:
it allows the generation of metal nanoparticles with a controlled size and size distribution;
it provides a mean to influence the chemical behavior of the metal nanoparticles through the direct interaction of the metal surface with the polymer-bound functional
groups. The aim of the current study is to prepare a H2O2 sensor based on palladium (Pd) nanoparticles supported on poly(thionine) (PTH). Cyclic voltammetry was used for polymerization of TH from aqueous solution. Pd nanoparticles were immobilized onto the polymer matrix by bulk electrolysis with coulometry from aqueous K2PdCl4 solution without supporting electrolyte.
2. Experimental
In electrochemical studies, a glassy carbon electrode (GCE) (r = 1.5 mm) was used as the working electrode. A saturated calomel electrode (SCE) was used as the reference electrode
and a Pt wire was used as the counter electrode. Bulk electrolysis with coulometry and cyclic voltammetry studies were carried out with CH Instruments System, Model 600E.
3. Results and discussion
PTH was coated onto the GCE surface by cyclic voltammetric scans between -0.4 V and +0.1 V vs. SCE from aqueous solution of TH containing 100 mM phosphate buffer (PBS, pH = 7.0) (Figure 1). PTH coated GCE was then washed with
distilled water and placed in a blank solution containing 100
mM PBS at pH 7.0 in order to record the cyclic voltammogram (CV) of the polymer film (Figure 2).
Oxidation and reduction peaks of the polymer were observed at -0.198 V and -0.233 V respectively. When we compare Figures 1 and 2, it is clear that the peak potentials are different than that of the monomer stating the formation of PTH.
Figure 1 Polymerization profile of TH
Figure 2 CV of PTH coated GCE
After this step, Pd nanoparticles were incorporated into the polymer matrix by bulk electrolysis from 2 mM K2PdCl4 solution at -0.8 V. It was observed that the so-prepared Pd/PTH modified GCE showed excellent catalytic activity towards reduction of H2O2 molecule which is involved in several biological events and is the by-product of many enzymatic reactions. So it is concluded that PTH supported Pd nanoparticles can be used to prepare an amperometric H2O2
biosensor.
References
[1] V. Ferreira, A. Tenreiro, L.M. Abrantes, Sensors and Actuators B, 119, 632 (2006). [2] A.W. Shi, F.L. Qu, M.H. Yang, G.L. Shen, R.Q. Yu, Sensors and Actuators B, 129, 779 (2008).
Poster Presentation – PP0241
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrochemical Impedimetric Immunosensor Based on Gold Nanoparticles
Functionalized Screen-Printed Gold Electrode for Carcinoembryogenic Antigen
(CEA) Tumor Marker Detection
Ş. Sultan1*, Ç. K. Rabia1 and K. Merve2
1 Department of Bioengineering, Yıldız Technical University, İstanbul, Turkey
2 Department of Medical Biology, S¿leyman Demirel University, Isparta, Turkey
*Presenter: sultan9019@gmail.com
Abstract
Impedimetric immunosensors are constructed with
antibody immobilization of working electrode and their
working principle is that occuring a correlation between
antigen concentration and obtained resistance after an
electrochemical Ab-Ag interaction. EIS is generally used to characterize these type detections in biosensor
applications [1]. Electrochemical impedimetric
biosensors have significant advantages for sensitive
detection of cancer biomarkers which are being smaller,
faster, more sensitive, cheaper devices, without
radiation hazards, allowing label-free, concurrent
detection, simple production, less time consuming, rapid
detection, having longer shelf life, and not complicated
procedure. These properties will substantially get easier
early dianostic of cancer at beginning phases.
Carcinoembryogenic antigens which are cell surface
glycoproteins [2] are used as an important biomarker in human serum associated with colorectal, lung, breast
cancer and ovarian carcinoma [3, 4]. CEA
quantification analysis with electrochemical impedance
spectroscopy promotes early diagnosis of cancer which
is crucial for the successful treatment of the disease and
increases health standards of people[5]. The gold layer
has various advantages during immobilization process
thereby the easy adsorption of biomaterials relates to
hydrophobic and thiol–gold interactions. In recent years,
gold nanoparticles (AuNPs) are commonly used to
enhance more sensitive electrochemical immunoassay for immobilization of antibody. AuNPs provide strongly
adsorbtion of antibody on working electrode during
immobilization due to its large specific surface area,
good biocompatibility, surface free energy of nanosized
particles [6, 7]. AuNPs facilitate electron transfer
between redox proteins and electrode surfaces, provide
effective mass transport in electrochemical biosensor
applications as making closer redox protein
(monoclonal CEA antibody) to the electrode via
nanosized structure. In the other words, AuNPs is a
desirable intermediator for immobilization of antibodies
[8]. In this study, the gold electrode is modified with thiol and AuNPs to develop an impedimetric biosensor
to detect CEA as an important cancer biomarker.
References
[1] M.I. Prodromidis, Impedimetric immunosensors-A
review, Electrochimica Acta, 55 (2010) 4227-4233.
[2] M. Taheri, U. Saragovi, A. Fuks, J. Makkerh, J.
Mort, C.P. Stanners, Self recognition in the Ig superfamily - Identification of precise subdomains in
carcinoembryonic antigen required for intercellular
adhesion, Journal of Biological Chemistry, 275 (2000)
26935-26943.
[3] X.L. Li, R. Yuan, Y.Q. Chai, L.Y. Zhang, Y. Zhuo, Y.
Zhang, Amperometric immunosensor based on toluidine
blue/nano-Au through electrostatic interaction for
determination of carcinoembryonic antigen, Journal of
Biotechnology, 123 (2006) 356-366.
[4] J. Wu, J. Tang, Z. Dai, F. Yan, H. Ju, N. El Murr, A
disposable electrochemical immunosensor for flow
injection immunoassay of carcinoembryonic antigen, Biosensors & Bioelectronics, 22 (2006) 102-108.
[5] J. Wang, Electrochemical biosensors: Towards point-
of-care cancer diagnostics, Biosensors & Bioelectronics,
21 (2006) 1887-1892.
[6] S.Y. Xu, X.Z. Han, A novel method to construct a
third-generation biosensor: self-assembling gold
nanoparticles on thiol-functionalized poly(styrene-co-
acrylic acid) nanospheres, Biosensors & Bioelectronics,
19 (2004) 1117-1120.
[7] D. Hernandez-Santos, M.B. Gonzalez-Garcia, A.C.
Garcia, Metal-nanoparticles based electroanalysis, Electroanalysis, 14 (2002) 1225-1235.
[8] J.M. Pingarron, P. Yanez-Sedeno, A. Gonzalez-
Cortes, Gold nanoparticle-based electrochemical
biosensors, Electrochimica Acta, 53 (2008) 5848-5866.
Poster Presentation – PP0242
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Custom fabricated MEMS-based Microgripper for Biological Cell
characterization
T. M. Khan1*, M. Yilmaz1, K. Topalli1, , and N. Biyikli1
1Bilkent University-UNAM, Institute of Materials Science and Nanotechnology, Ankara, Turkey
* Presenter: talha.khan@bilkent.edu.tr
Abstract
We present Micro-Electro-Mechanical-Systems
(MEMS) based microgripper that is used for biological
cell characterization. The electrostatically actuated
microgripper is fabricated using a custom
microfabrication process which includes 3 mask
lithographic processes followed by non-conventional
jaw release methodology. The microgripper is tested for
micro-particles ranging from 10-30 µm size and a co-relation is established to further verify its effectiveness
in cell characterization using electrostatic comb sensing.
Introduction
MEMS-based microgripper is essentially a miniaturized
robotic hand. They have a number of applications
ranging from pick and place of micro-objects to material
characterization. Microgrippers can be actuated or
sensed used thermal, electrostatic and magnetic
techniques [1]. We use electrostatic comb drive with a
common ground to be used as both sensor and actuators. The conventional microfabrication of MEMS devices
include SOI-MUMPS (Silicon on Insulator-Multi user
MEMS Process) by MEMSCAP Inc. that are patterned
from both sides to release the structures and are further
diced. This adds a limitation to integration of structures
that are outlying the main chip area. A microgripper for
example, requires its jaws to reach out well outside the
actuation area to grasp the object. In order to overcome
this problem, we add custom patterns that can be
scribed off to suspend the jaws. Additionally a three
pronged jaw deign is introduced to actively release samples, after manipulation. The jaws are designed to
hold cells from 10-30 µm in size. The third beam works
as a plunger to remove adhered cells off the jaws to
make them usable again (Figure 1)
The fabrication process starts with a double side
polished SOI wafer with structural layer of 15 µm with
2 µm oxide and 500 µm of handle layer. Initially a
lithographic process is made followed by metal
deposition using e-beam evaporation and patterned via
lift-off for metal bonding. The top layer is then
patterned using standard lithography process and Dry
etch is achieved to reach the oxide layer (Figure 2). Wafer is then flipped and back side is patterned using
Deep Reactive Ion Etching (DRIE) in Inductively
Coupled Plasma (ICP). The Microgripper is then scribed
into smaller dies and then exposed to a Vapor HF
process to remove the underlying silicon dioxide layer.
In order to release the jaws, we introduced special
patterns that are used to scribe off the undesired areas.
The Microgripper is then bonded to a readout circuitry
to actively receive sensing output. The microgripper is
initially tested with polymer micro particles to better
understand the sensing mechanism before characterizing
biological cells.
The proposed custom fabrication for MEMS
microgripper is simple and effective for cell
characterization. The details of fabrication and
measurement results will be discussed in the full paper and at the conference.
Figure 1 Three pronged jaws to actively hold
Biological cells.
Figure 2 Microgripper with patterned top layer.
References
[1] Y. Jia and Q. Xu, “MEMS Microgripper Actuators
and Sensors: The State-of-the-Art Survey”, Recent Patents on Mechanical Engineering 2013, Vol. 6,
No. 2
Poster Presentation – PP0156
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
NO gas sensing properties of CuO nanostructure at low operating temperature
Tuğba Çorlu1*, Irmak Karaduman1, Memet Ali Yıldırım2, Aytunç Ateş3 and Selim
Acar1
1 Department of Physics, Science Faculty, Gazi University, Ankara, Turkey
2Department of Electric Electronics Engineering, Engineering Faculty,
Erzincan University, Erzincan, Turkey
3Department of Material Engineering, Engineering and Natural Sciences Faculty, Yıldırım Beyazıt University, Ankara, Turkey
*Presenter: tugbacorlu@gmail.com
Abstract
Recently, much attention related to health care has been
growing as life expectancy is remarkably extended due
to the advancement of medical treatment and early diagnosis. As medical technologies develop, individuals
receive more medical benefits and expect more
convenient ways in diagnosis. According to the recent
developments of technology, physical conditions of
human body can be easily monitored by analyzing
biomarker gases from human breath [1]. Concentration
of these biomarker gases in exhaled breath of the patient
are prone to substantial increase compared to that in the
breath of healthy people. Among them, NO gas is a
critical marker of respiratory diseases [2]; the accurate
detection of NO in human breath can give early diagnosis of asthma and lung cancer. Therefore, NO
sensors with high sensitivity and fast response are
required for environment monitoring, combustion
emission control and human health diagnosis. Many
efforts have been made to develop NO sensors with
good performance [3].
Among the sensors investigated and developed, CuO
based sensors received much attention since they can detect a wide variety of gases with high sensitivity,
good stability and also low production cost [3]. Copper
oxide is a well-known p-type semiconductor with a
narrow band gap of 1.2 eV and has been extensively
studied becauseof its versatile applications, such as
catalysts, magnetic storagemedia, gas sensors, lithium
batteries, amperometric sensors, etc. Because the
practical performances of CuO nanomaterials are close related to its morphology and size, which ultimately
depends on the preparation methods and reaction
conditions , various methods have been developed to
synthesize CuO nanostructures, for example, thermal
oxidation of copperfoil, hydrothermal route, vapor-
liquid-solid synthesis, ultra sound irradiation, thermal
decomposition of precursors, SILAR, etc. [4]. The
SILAR method is low cost, simple and suitable for large
area deposition. Thin films can be used since the
deposition is carried out at or near to room temperature.
by Successive ionic layer adsorption and reaction
(SILAR) method with 15 cycle and investigated the gas
sensing properties. The gas sensing properties of the
CuO nanostructures were measured at different
operating temperatures and depending on different NO
and CO concentrations in air. It can be noted that the
sample exhibited acceptable response to 1 ppm NO gas
concentration. The possible sensing mechanism between the producing method and the sensing surface were
proposed.
Figure 1 SEM image of CuO film with 15 cycle
Acknowledgement: This work is supported by The
Scientific and Technological Research Council of Turkey
(TUBITAK) under Project No: 115M658 and Gazi
University Scientific Research Fund under Project No:
05/2015-09.
References
[1] A. Rydosz, A. Szkudlarek, Sensors 15, (2015) 20069-
20085
[2] Y. B. Li, Z. W. Huang, S. Q. Rong, Sensors Materials
18 (2006) 241-249
[3] Z. –X Cai, H. –Y. Li, X. –N. Yang, X. Guo Sens.
Actuators B 219 (2015) 346-353
[4] M. A. Yıldırım, Y. Akaltun, A. Ateş Solid State
Sciences 141 (2012) 1282-1288
Poster Presentation – PP0243
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Improvement of Immobilization and Spotting Techniques of Biosensors
Including Oligonucleotid Probe
Yagmur Guler1*, Mert Muhammed Koc1, Merve Kucukoflaz 1, Şengül Kurtuluş 1, Mehmet Ali Boz1 and Mustafa
Oguzhan Caglayan1
1Nanotechnology Engineering Department, Cumhuriyet University, Sivas, Turkey
*Presenter: yagmurrgulerr@gmail.com
1.Introduction
DNA microarray technologies have been used in
molecular biology since 20 years. With the
improvement of this technology, the new applications
techniques like protein microarray techniques, cells on
chips and comparative genomic hybridization have also
been used and new integrated devices like micro total
analysis systems (µTAS) and lab-on-a-chip have been
improved. However, these techniques often face some
reliability problems. In order to use DNA series
optimally, during the analytical application the actual situations and the physicochemical events for each
operation must be understood exactly. The most
important step during biosensor production is the
volatilization of the solvent in immobilization step,
irrespective of the analytical method being used. During
volatilization, ODN concentration in the droplet
increases and as a result, the immobilization kinetics
accelerates. During the volatilization of the droplet, by
dispersion of the ODNs in the droplet/ spot irregularly,
the cyclic morphology of spot occurs in demilunar or
any kind of undesired form. These kinds of
inhomogenities in and between spots cause errors in obtaining sensor signals and interpreting the results. The
most ideal case is each spot should be similar to
immobilized ODN probe and dispersed uniform.
2.Materials and Methods
In the presented project, for determining the appropriate
immobilization conditions, researching the conditions of
the spots volatilization on microarrays is being purposed
considering both the material interactions between
probe – base and direct adsorption situations. The
project were completed by improving the conditions of
the immobilization of the probes (ODN and/or protein probe) on to substrate modified by self-assembled
monolayers which reacts with these different reactive
groups by using (micro)spotting techniques; developing
a general mechanism for commercial ODN probes
which are approximately 30 base pair (bp) and
determination of the general volatilization conditions;
improving the volatilization conditions by adding non-
Newtonian fluids (polymeric components and/or
nanofluids) in the solution forming the ODN probes and
researching the volatilization conditions and
immobilization kinetics; and finally, by providing the
most appropriate geometry and spotting conditions for non-Newtonian fluids added ODN solutions.
3.Results
After obtaining function using droplets of the Young-
Laplace equation modeling it was performed and the
modeling results with measurement results with
functions with droplets function were compared.
Comparative process was performed on the contact
angle values are obtained. This method was carried out
with the contact angle measurements are obtained using
different fluids on the Si substrate compared to the
normal measurement process.
Table 1 The contact angle which was obtained by using
different fluids and Si substrates values and standard
deviation values (not including modeling)
Base Material
Fluid Left Right Average
Si wafer %80 Tripropylene glycol - %20 water
38.1±2.4 39.4±2.6 38.6±2.6
Si wafer %40 Tripropylene glycol - %60 water
59.6±2.6 57.4±2.7 58.2±2.9
Si wafer %20 Tripropylene glycol - %80 water
68.9±2.9 69.1±2.8 68.3±2.4
Si wafer %10 Tripropylene glycol - %90 water
78.4±2.8 80.1±2.2 79.1±2.4
Table 2 The contact angle which was obtained by using
different fluids and Si substrates values and standard
deviation values(including Young- Laplace modeling)
Base Material
Fluid Left Right Average
Si wafer %80 Tripropylene
glycol - %20 water
37.3±1.2 38.1±1.6 37.7±1.1
Si wafer %40 Tripropylene glycol - %60 water
57.3±1.3 57.4±1.7 57.2±1.2
Si wafer %20 Tripropylene glycol - %80 water
66.3±0.9 66.1±0.8 66.2±0.6
Si wafer %10 Tripropylene glycol - %90 water
76.2±0.8 76.5±1.2 76.1±0.9
In this Project results were obtained: Droplet model
obtained by solving the equation was used to Young-
Laplace using contact angle measurement on different
substrates. Droplet model with the measurement results
obtained contact angle was seen with ow Standard
deviation of 2σ’s. There is a significant relationship
between the kinetics of ODN probes immobilized by contact angle measurements. In studies that use TRIS an
PBS buffer solutions which SH functional end on the Au
surface as stated in the literatre TRIS buffer
immobilization of ODN probes was observed that a
beter performance. A biolgical agent such as Tween 20,
the use of immobilization solution increases the
immobilization rate. The effects of nanoparticles, in all
the buffer solution may be for interacting with the
tertiary structure ODN. The most important output of
the project, diffirent substrate is also suitable for an
improved measurement method.
Poster Presentation – PP0244
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Preparation and Characterization of Graphene/Conducting Polymer
Composites Coated Surfaces
Yaşar Bayramlı1*, Filiz Kuralay1 and Bora Garipcan2
1Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey
2Institute of Biomedical Engineering, Boğaziçi University, 34684 Istanbul, Turkey
*Presenter: yasarbayramli@hotmail.com
Abstract
Conducting polymers (CPs) are organic polymers that
conduct electricity. They are of quite importance with
respect to various materials in terms of application since they have unique electrical and optical properties. These
polymers have porous structures and high surface areas.
According to their oxidation states and doped/undoped
forms, their volumes change. Thus, conducting
polymers are widely used in many areas such as
biochemistry, medicine, pharmacy and nanotechnology.
Electropolymerization of their monomers result in
polymer films, which are uniform and strongly adherent
to the electrode surface [1,2].
Graphene (GR) is a single layer of carbon atoms packed
into a two-dimensional honeycomb lattice. Graphene-
based nanomaterials have drawn considerable interest
due to its unique physicochemical, thermal and
mechanical properties including large specific surface
area, excellent electrocatalytic activity, good electrical
conductivity, high mobility of charge carriers and
unique transport performance. It has been a great
potential for various researches, such as electrochromic
devices, lithium batteries, supercapacitors, solar cells and sensing devices [3,4].
In this study, preparation of graphene/conducting
polymer nanocomposites coated electrodes were
achieved using cyclic voltammetry (CV) and constant
potential electrolysis. For the electropolymerization
process, pyrrole and 3,4-ethylenedioxythiophene
monomers were used. Thus, graphene/polypyrrole and graphene/poly(3,4-ethylenedioxythiophene) coated gold
electrode (AuE), platinum electrode (PtE) and glassy
carbon electrode (GCE) were obtained. The
electrochemical behaviors of the coated surfaces were
examined with cyclic voltammetry and electrochemical
impedance spectroscopy (EIS). Various cyclic scans and
electropolymerization times were used in order to
investigate the changes in the electrochemical behaviors
of the coated electrodes. We believe that the coated
electrodes later on can be used for different applications
such as biosensing and biofuel cell applications.
Acknowledgments: F. Kuralay acknowledges Turkish
Academy of Sciences (TÜBA) as an associate member
and TÜBA-GEBİP programme.
References
[1] F. Kuralay, A. Erdem, Analyst 140 (2015) 2876-
2880.
[2] F. Kuralay, H. Özyörük, A. Yıldız, Sensors and
Actuators B: Chemical 109 (2005) 194-199.
[3] M. Pumera, The Chemical Record 9 (2009) 211-223.
[4] B. Pérez-López, A. Merkoçi, Microchimica Acta
179 (2012) 1-16.
Poster Presentation – PP0246
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Sensitive Determination of Ceftizoxime by Graphene Oxide/Gold Nanoparticle
Modified Pencil Graphite Electrode
Yeşim Tuğçe Yaman1*, Ceren Yardımcı2 and Serdar Abacı3
1 Department of Chemistry, Graduate School of Science and Engineering, Hacettepe University,
Ankara, Turkey 2Department of Analytical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara, Turkey
3Department of Chemistry, Faculty of Science, Hacettepe University, Ankara, Turkey
*Presenter: tugce.yaman@hacettepe.edu.tr
Introduction
Ceftizoxime (CFX), is the third generation
cephalosporin antibiotic. It interferes the formation of
the bacterium’s cell wall causing the wall to rupture
which results the death of bacteria [1]. There are many
studies that have been published regarding the detection
and analytical control of CFX by chromatographic and
spectroscopic methods which are highly sensitive and
have low detection limit, they have high costs, a time-
consuming process and require trained technicians.
Because of these drawbacks in this study, determination
of CFX was performed by electrochemical methods.
Method
Cyclic voltammetry (CV) was performed for identifying
oxidation peak of CFX and to show the effect of
modified electrode for the peak current response of
CFX. Square wave anodic stripping voltammetry
(SWASV) was recorded from the 0.6 V to 1.0 V (vs.
Ag/AgCl) after 300 seconds and 0.6 V (vs. Ag/AgCl)
accumulation time and deposition, respectively. Square
wave voltammetry parameters were examined. The
optimized values were amplitude 4 mV, pulse size 50
mV, frequency 50 Hz.
Results and Discussion
Surface morphology of bare and modified electrodes
was performed by scanning electron microscopy (SEM).
Fig.1.a shows that bare PGE surface has irregular
graphite layer. Because of the GO sheet entangled with
each other, the single- or few-layer GO nanosheets were
with lots of wrinkles (Fig.1.b). When AuNP was
deposited onto the PGE by electrolysis, AuNP was
formed as spherical structure (Fig.1.c,d).
Figure 1. SEM images of a) Bare PGE, b) GO modified PGE, c) AuNP modified PGE, d) AuNP/GO modified
PGE. (Magnitude: 35000)
The electrochemical behavior of CFX was investigated
by cyclic voltammetry (CV) at bare and modified PGE
surfaces. (Figure 1).
Figure 2. Cyclic voltammogram of 50 µM CFX at (a)
bare, (b) GO modified, (c) AuNP modified, (d)
AuNP/GO modified PGE. (e) blank solution pH 3 BRT.
(Scan rate:100 mVs-1)
In Figure 2, after the surface modification with
AuNP/GO, oxidation peak current of CFX was
increased. This result shows the catalytic effect of
AuNP/GO surface on the CFX oxidation peak current.
Parameters affecting the experimental conditions, such
as the electrodeposition time of AuNP, physical
adsorption time of GO, pH, accumulation time, deposition potential, etc., were investigated for the
maximum performance of the electrode. Under
optimized conditions, the limit of detection and the limit
of quantity were found to be 0.4 nM and 1.2 nM for
CFX, respectively. This new sensor system offered the
advantages of simple fabrication, low cost, fast
response, high sensitivity, low background current and
low detection limit for CFX. This new sensor system
was successfully tested for the quantitative detection of
the CFX in a pharmaceutical preparation.
Acknowledgement: The authors thank to Research
Council of Hacettepe University for financially supporting to this study (THD-2015-7394).
References
[1] S. Shahrokhian, S. Ranjbar, M. Ghalkhani,
Electroanalysis. 28 (2016) 469–476.
Poster Presentation – PP0247
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Modeling of a Photonic Crystal Fiber Based Dye Laser
Z. Rashida, K. Çiçeka, and A. Kiraza,b*
a Koç University, Department of Physics, Sariyer, Istanbul
b Koç University, Department of Electrical and Electronics Engineering, Sariyer, Istanbul
*Preenter:: akiraz@ku.edu.tr
Abstract
Photonic crystal fiber (PCF) is a new class of
microstructured optical devices which confine and
guide light by the structural modifications and not
only by the refractive index contrast. PCFs are
finding applications in highly sensitive gas sensors,
biesensors and fiber lasers because of augmented
light matter interaction in the transparent core or the
neighbourhood. PCF is a promising technology for enhancing the power levels of fluidic lasers because
of its increased flexibility in singlemode core sizes,
the increased numerical aperture of pump cores in
doubleclad fiber configurations and the high
thermal stability of lowloss allglass structures.
Associated with less bending loss, controlled
dispersion and variable group velocity, the use of
photonic crystal fibers as host medium for the active
biological gain medium to develop a fiber laser
opens new prospects due to photobleaching and self
healing in the field of biophotonics.
We present a mathematical model of a PCF
laser based on coupled first order rate equations
incorporating rhodamine B dye as a gain medium in
the air cladding region of the suspended core PCF.
The mode profile of the pump and signal is
examined by finite element method which is used to
calculate the effective mode index and pump and
signal filling factors. We analyze the behavior of the system under different dopant concentration, length
of the fiber, scattering loss at pump and signal
wavelengths and input pump power. The parametric
study, as a result, computes the threshold pump
power, slope efficiency, pump and signal power
distribution in both directions, fraction of number of
atoms in upper level of the energy state and
optimum length.
Poster Presentation – PP0232
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Amperometric Uric Acid Biosensor Based on Magnetite Nanoparticles Modified
Carbon Paste Electrode
Z.Ö.Erdoğan1*, S.Küçükkolbaşı1, P.E.Erden2 and E. Kılıç2
1Department of Chemistry, Faculty of Science, Selcuk University, 42075 Konya, Turkey 2Department of Chemistry, Faculty of Science, Ankara University, 06100 Ankara, Turkey
*Presenter: duruzera@gmail.com
Abstract
Uric acid (2,4,6-trihydroxypurine) is an end product
from purine derivatives in human metabolism.
Abnormal levels of uric acid in biological fluids is a
symptom of many diseases such as gout, hyperuricemia,
diabetes, renal disease and Lesch-Nyhan syndrome.
Therefore, fast and reliable determination of uric acid in
biological fluids is routinely required for diagnosis and
treatment. [1]. Various methods, including
spectrophotometry, enzymatic testkits, high-
performance liquid chromatography, capillary electrophoresis, chemiluminescence and
electrochemical techniques, is used for the detection of
uric acid. Nevertheless, most of these methods are very
laborious, expensive, time-consuming and/or complex
to perform [2, 3]. Among these methods, especially
electrochemical technique for the determination of uric
acid is very interesting, because this technique directly
provides real-time and on-line data analysis without
need for pre-seperation process.
Figure 1 Uric Acid
In this study, carbon paste enzyme electrode based on
Fe3O4 nanoparticles for uric acid determination was
fabricated. The carbon paste electrode was prepared by
mixing magnetite nanoparticles (Fe3O4), uricase
enzyme, graphite powder and paraffin oil and the paste
was placed into a teflon electrode body. Electron
transfer properties of unmodified and Fe3O4
nanoparticles modified carbon paste electrodes were investigated by cyclic voltammetry.
The voltammetric study indicated that the presence of
Fe3O4 nanoparticles results in increased electroactive
surface area and enhanced electron transfer. The
parameters affecting the analytical performance of the
enzyme electrode such as enzyme loading, nanoparticle
amount, pH, buffer concentration and working potential
were investigated. Analytical characteristics of the presented biosensor were also studied. The working
range of the enzyme electrode was 1-1000 μM,
detection limit was 1μM and response time was 50 s.
Figure 2 The mechanism of the biosensor
In conclusion the cost of the biosensor is low and its
fabrication process is very simple. The biosensor exhibit good operational and storage stability. Therefore, the
presented biosensor offers a good promise for practical
applications in real samples. Our future study will be
focused on the the use of the enzyme electrode for uric
acid determination in real samples.
References:
[1] K. Jindal, M. Tomar, V. Gupta, Biosensors and
Bioelectronics 38 (2012) 11-18.
[2] J. Arora, S. Nandwani, M. Bhambi, C.S. Pundir,
Anal. Chim. Acta 647 (2009) 195-201.
[3] Erden, P.E., Kılıç, E., Talanta, 107, (2013) 312–323.
Poster Presentation – PP0248
3rd International Congress on Biosensors, 5-7 October 2016, Ankara
Electrodeposition and Characterization of Cu3Te2Te2 Thin Films
ZehraYazar Aydın1* and Serdar Abacı2
1Hacettepe University, Graduate School of Science and Engineering, Department of Nanotechnology
and Nanomedicine, Ankara, Turkey 2Hacettepe University, Faculty of Science, Department of Chemistry, Ankara, Turkey
*Presenter: zehraaydin@hacettepe.edu.tr
Introduction
Today, synthesis of compound semiconductors is both
technologically and scientifically very important
because of many applications in the optoelectronic and
high efficiency solar cells. Thin chalcogenide films are
of particular interest for the fabrication of large area
photodiode arrays, solar cells, photoconductors, sensors, etc [1]. This study, Cu3Te2Se2 nanofilms were
synthesized using underpotential deposition (UPD)
based electrochemical codeposition from the same
solution at constant potential.
Method
Cu3Te2Te2 nanofilms were synthesized by the UPD-
based electrochemical codeposition technique at room
temperature from a solution containing both Cu+2 and
HTeO2+, H2SeO3. Cyclic voltammetry and potential-
controlled electrolysis methods were used for the
electrochemical characterization. Cu3Te2Se2 thin films were deposited via potential-controlled electrolysis on
Au plate. The synthesized nanofilms were characterized
by X-ray diffraction (XRD) and X-ray photoelectron
spectroscopy (XPS).
Results and Discussion
The electrochemical behaviors of Cu, Te, Se and
Cu3Te2Se2 system in the UPD and bulk regions were
investigated on polycrystalline Au electrodes by cyclic
voltammetry measurements (Figure 1).
Figure 1. a) Cyclic voltammograms 0.1 M H2SO4 at pH
0.5 on Au electrode. 2 mM CuSO4 (black), 2 mM TeO2
(red) and 0,2 mM SeO2 (green) b) Cyclic
voltammogram recorded in 0.1 M H2SO4 (blank
solution) for CuTe deposited at 0.1 V electrolysis (blue)
Figure 2 shows the 20°–80° 2θ range of the XRD pattern of the CuTe nanofilm deposited at 0.2 V onto an
Au substrate.
Figure 2. XRD pattern of a Cu3Te2Se2 nanofilm
deposited onto an Au substrate.
XRD results showed that the Cu3Te2Se2 films are crystalline and a single phase (Figure 2).
The stoichiometric ratios of the components in the
deposited films were determined via XPS. According to
calculations based on the XPS data, the Cu:Te:Se ratio
in the deposited films is approximately 3:2:2.
Consequently, the synthesis of copper chalcogenides
nanofilms using underpotential deposition (UPD) based
electrochemical codeposition method can be inexpensively and easily performed under atmospheric
conditions without requiring difficult-to-use and
expensive equipment.
Acknowledgements: This work was funded by the
Scientific and Technological Research Council of
Turkey (TUBITAK) under project number 138366
References
[1] Sakr, G.B., Yahia, I.S., Fadel, M., Fouad, S.S.,
Romcevic, N. 2010. Journal of Alloys and Compounds.
507, 557–562.
Poster Presentation – PP0249
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