Nanobiosensors

Sara Huefner

November 6, 2006

Outline

• Biosensor Background– What is a Biosensor?– Components of a Biosensor– Principles of Detection

• Biosensors on the Nanoscale– Current Research– Potential Applications

• Conclusion

What is a Biosensor?“Biosensor” once refered to any device which responds to chemical

species in biological samples or using biological components.

www.wvminesafety.org http://www.gentronix.co.uk/images/newscientist.jpg

Current Definition for Biosensors:

A sensor that integrates a biological element with a physiochemical transducer to produce an electronic signal proportional to a single analyte

which is then conveyed to a detector.

www.imec.be/ovinter/static_research/BioHome.shtml

Components of a Biosensor

http://www.dddmag.com/images/0409/HTS1_lrg.jpg

Detector

1ST Component: Biological Element

Microorganism

Tissue

Cell

Organelle

Nucleic Acid

Enzyme

Enzyme Component

Receptor

Antibody

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.

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

Principles of Detection

measures change in mass

measures change in electric distribution

measures change in light intensity

measures change in heat

Principles of DetectionPiezo-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.

Principles of DetectionElectrochemical Biosensors

•Amperometric for applied current: Movement of e- in redox

reactions detected when a potential is applied between two

electrodes.

•Potentiometric for voltage: Change in distribution of charge is

detected using ion-selective electrodes, such as pH-meters.

•Conductimetric for impedance

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

Principles of Detection

Optical 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. www.manimo.it/Prodotti/

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

Biosensors on the NanoscaleCurrent Research

Dr. Michael Strano at the University of] Illinois, "We have developed molecular sheaths around the nanotube that respond

to a particular chemical and modulate the nanotube's optical properties."

http://www.worldchanging.com/archives/001727.html

Biosensors on the NanoscaleCurrent Research

SPOT-NOSED Project: A layer of olfactory proteins on a nanoelectrode could react with low-concentration odorants. This

technology could be used by doctors to diagnose diseases at earlier stages.

http://www.sciencedaily.com/releases/2006/05/060515095600.htm

Biosensors on the NanoscaleCurrent Research

Nanosphere lithography (NSL) derived triangular Ag nanoparticles were used to detect streptavidin down to one

picomolar concentrations.http://www.chem.northwestern.edu/~vanduyne/pdf/MRS_723_O311-0316_2002.pdf

http://faculty.washington.edu/stenkamp/stefanieweb/hydro.html

Biosensors on the NanoscaleCurrent Research

The School of Biomedical Engineering has

developed an anti-body based piezoelectric nanobiosensor to be used for anthrax,HIV hepatitis detection.

http://www.biomed.drexel.edu/TechPort/Contents/Lec/Overview/Lec_BioSensors.pdf

Potential Applications

www.fuji-keizai.com/e/report/biosensor2004_e.html

• Clinical diagnostics• Food and agricultural processes• Environmental (air, soil, and water) monitoring• Detection of warfare agents.

Conclusion

http://www.must.edu.my/~ccyeo/topics/biosensor.jpg

The possibilities are endless!