Biosensor and nanobiosensor

In The Name of God

Biosensor and Nanobiosensor

Present by: Farhad Ghanizadeh

present by: Farhad Ghanizadeh 2

• Sensor• Biosensor• Nanobiosensor• Applications


Basic Sensor Technology

• A sensor is a device that in special situation , react predictable reactions.

• It converts a physical(or chemical) phenomenon into a (an electrical) signal.

• the interface between the physical world and the world of electrical devices.

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Sensors• Chemical sensors

– Thermal sensors– Mass sensors– Electrochemical sensors

–Potentiometric–Amperometric –Conductance

–Photo sensors

• Synthesis sensors

•Biosensors


• any biological or chemical sensory points used to convey information

Human senses


Biosensor Any device that has specific biochemical reactions to

detect chemical compounds in biological samples.

FATHER OF BIOSENSOR.

Professor Leland C Clark Jnr

(1918–2005)He is most well known as the inventor of the Clark electrode, a device used for measuring oxygen in blood, water and other liquids.

https://en.wikipedia.org/wiki/Clark_electrode


Data & Information

EEG sensor

Doctor PCECG sensor

B.P sensor

Thermo Sensor

Blood O2 Sensor

Mobility sensor

Muscle sensor

Weight sensor

network server

Analyze and offer medical treatment


BIOSENSOR

Analyte

Sample handling/preparation

Detection

SignalAnalysis

Response


• A biosensor can be defined as a device containing biological material (such as antibody) connected to a transducer which can measure electronical changes of signal.

• Many possible biological molecules (enzymes, antibodies, oligonucleotides, microorganisms, mammalian cells, etc.) can be combined with various transducers, which are based on electrochemical, optic, and mass changes, to construct the biosensor.


COMPONENTS

DetectorCdl: The Chemical Descriptors Library (CDL) is a C++ library that provides functionality in the area of chemical informatics


1ST Component: Biological Element

MicroorganismTissueCellOrganelleNucleic AcidEnzymeEnzyme ComponentReceptorAntibody

The component used to bind the target molecule.

http://www.chemistry.wustl.edu/~edudev/LabTutorials/HIV/DrugStrategies.html

Must be highly specific, stable under storage conditions, and immobilized.


transducersA device which converts

one form of energy to another

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2ND Component: Physiochemical Transducer

Acts as an interface, measuring the physical change that occurs with the reaction at the bioreceptor then transforming that energy into

measurable electrical output.


3RD Component: Detector

Signals from the transducer are passed to a microprocessor where they are

amplified and analyzed.

The data is then converted to concentration units and transferred to a display or/and

data storage device.

www.modernmike.com


WORKING PRINCIPLEAnalyte diffuses from the solution to the surface of the Biosensor.Analyte reacts specifically & efficiently with the Biological Component of the Biosensor.This reaction changes the physicochmical properties of the Transducer surface.This leads to a change in the optical/electronic properties of the Transducer Surface.The change in the optical/electronic properties is measured/converted into electrical signal, which is detected.


Basic characteristics of a biosensor

1- The biocatalyst must be highly specific for the purpose of the analyses, be stable under normal storage conditions and, except in the case of colorimetric enzyme strips show good stability over a large number of assays (i.e. much greater than 100).

2- The reaction should be as independent of such physical parameters as stirring, pH and temperature as is manageable. This would allow the analysis of samples with minimal pre-treatment. If the reaction involves cofactors or coenzymes these should, preferably, also be co-immobilised with the enzyme.


Basic characteristics of a biosensor3- The response should be accurate, precise, reproducible and linear over the useful analytical range, without dilution or concentration. It should also be free from electrical noise:

Linearity: Maximum linear value of the sensor calibration curve. Linearity of the sensor must be high for the detection of high substrate concentration.

Sensitivity: The value of the electrode response per substrate concentration.

Selectivity: Interference of chemicals must be minimised for obtaining the correct result.

Response time: The necessary time for having 95% of the response.


Basic characteristics of a biosensor4- If the biosensor is to be used for invasive monitoring in clinical situations, the probe must be tiny and biocompatible, having no toxic or antigenic effects. If it is to be used in fermenters it should be sterilisable. This is preferably performed by autoclaving but no biosensor enzymes can presently withstand such drastic wet-heat treatment. In either case, the biosensor should not be prone to fouling or proteolysis.


Basic characteristics of a biosensor5- The complete biosensor should be cheap, small, portable and capable of being used by semi-skilled operators.

6- There should be a market for the biosensor. There is clearly little purpose developing a biosensor if other factors (e.g. government subsidies, the continued employment ofskilled analysts, or poor customer perception) encourage the use of traditional methods and discourage the decentralization of laboratory testing.


ADVANTAGES

Highly Specific.Independent of Factors like stirring, pH, etc.Linear response, Tiny & Biocompatible.Easy to Use, Durable.Require only Small Sample Volume.Rapid, Accurate, Stable & Sterilizable.



Principles of Detection

measures change in mass

measures change in electric distribution

measures change in light intensity

measures change in heat

Mass sensitive measurementPiezo-Electric Biosensors

The change in frequency is proportional to the mass of absorbed material.

Some piezo-electric devices utilize crystals, such as quartz, which vibrate under the influence of an electric field. The frequency of this oscillation depends on their thickness and cut.

electronics.howstuffworks.com Others use gold to detect the specific angle at which electron waves (surface plasmons) are emitted when the substance is exposed to laser light.

http://images.google.com/imgres?imgurl=http://static.howstuffworks.com/gif/quartz-watch-crystal.jpg&imgrefurl=http://electronics.howstuffworks.com/quartz-watch2.htm&h=244&w=290&sz=13&hl=en&start=1&tbnid=PTnbJaV6CHpIHM:&tbnh=97&tbnw=115&prev=/images?q=quartz+crystals&svnum=10&hl=en&lr=


piezoelectric immunosensor

Principles of DetectionElectrochemical Biosensors

• Conductometric measurements, which measures changes in the conductance of the system due to the presence of the analyte.

• Amperometric measurements, which involves measuring the current generated by electrochemical oxidation or reduction of electroactive species at a constant applied potential.

• Potentiometric measurements, which measures the electrical potential difference between a working and reference electrode.

http://www.lsbu.ac.uk/biology/enztech/index.html

Principles of DetectionOptical Biosensors

• Colorimetric for color: Measure change in light adsorption as reactants are converted to products.

• Photometric for light intensity: Photon output for a luminescent or fluorescent process can be detected with photomultiplier tubes or photodiode systems.

Principles of DetectionCalorimetric Biosensors

If the enzyme catalyzed reaction is exothermic, two thermistors may be used to measure the difference in resistance between reactant and product and, hence, the analyte concentration.

www4.tsl.uu.se/~Atlas/DCS/DCSIL/therm.html


A schematic representation of an electrochemical sensor


Multienzyme system for the electrochemical detection of

Phenylalanine


Nano-biosensors


Applications of NanobiosensorsBiological Applications• DNA Sensors; Genetic monitoring, disease• Immunosensors; HIV, Hepatitis,other viral diseas, drug

testing, environmental monitoring…• Cell-based Sensors; functional sensors, drug testing…• Point-of-care sensors; blood, urine, electrolytes, gases,

steroids,drugs, hormones, proteins, other…

• Bacteria Sensors; (E-coli, streptococcus, other): food industry,medicine, environmental, other.

• Enzyme sensors; diabetics, drug testing, other.Environmental Applications• Detection of environmental pollution and toxicity• Agricultural monitoring• Ground water screening • Ocean monitoring


• The use of nanostructured materials for the construction of biosensors presents the possibility of achieving new levels of sensitivity with miniaturized and highly multiplexed devices.

• Structures with the dimensions of biomolecules (e.g., 5–20 nm) are particularly attractive, as the size complementarity could assist in increasing sensitivity, or eventually even allow single-molecule measurements.



• The rationale for the interest in using carbon nanotubes to facilitate communication between enzymes and the outside world, and why efficient transfer of electrons will result in improved biosensing and bioelectronic devices, is perhaps best exemplified by the enzyme GOx. This oxidoreductase enzyme oxidizes glucose to gluconolactone. The oxidation of glucose and the completion of the catalytic cycle.


• Schematic of a classical first generation enzyme electrode using GOx as an example where glucose is oxidized to gluconolactone and in the process the redox-active center of GOx, FAD is reduced to FADH2. The FADH2 is then oxidized back FAD by freely diffusing oxygen. The oxygen is reduced to hydrogen peroxide, which is detected at the electrode.



• Illustrates the desired end goal of this research where a carbon nanotube is plugged into the enzyme and the reoxidation of the FADH2 is achieved via direct electron transfer.



Cantilever Biosensors

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Health & Medicine

Biosensor and nanobiosensor