nanobiosensors sara huefner november 6, 2006. outline biosensor background –what is a biosensor?...
TRANSCRIPT
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
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.