Biosensors are devices used to detect the presence or concentration of a biological analyte.

1. NANOBIOSENSORS
Samova Sanman
Samova.sanman@gmail.com

2. Outline
• Biosensor Background
• What is a Biosensor?
• Components of a Biosensor
• Principles of Detection
• Biosensors on the Nanoscale
• Current Research
• Potential Applications
• Applications of Nanobiosensors

3. Biosensor
• “Biosensor” once refered to any device which
responds to chemical species in biological samples
or using biological components.
• A sensor that integrates a biological element with a
physiochemical transducer to produce an electronic
signal proportional to a single analyte which is then
conveted to a detector.

4. Components of a Biosensor
Detector

5. Biological Element
Microorganism Tissue Cell
Organelle Nucleic Acid
Enzyme Enzyme Component
Receptor Antibody
The component used to bind the target molecule.
Must be highly specific, stable under storage conditions, and
immobilized.

6. 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.

7. 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.

9. Principles of Detection
• measures change in mass
• measures change in electric distribution
• measures change in light intensity
• measures change in heat

10. Principles of Detection
• Piezo-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.
Others use gold to detect the specific angle at
which electron waves (surface plasmons) are
emitted when the substance is exposed to laser
light.

11. Electrochemical 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.

12. 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.

13. Calorimetric 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.

14. Biosensors
on the Nanoscale
Current Research

15. • 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."

17. • 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.

18. • Nanosphere lithography (NSL) derived
triangular Ag nanoparticles were used to
detect streptavidin down to one picomolar
concentrations.

19. • The School of Biomedical
Engineering has
developed an anti-body
based piezoelectric
nanobiosensor to be used
for anthrax,HIV hepatitis
detection.

20. Optical Nanobiosensors
A sensor that uses light to detect the effect of a chemical on a
biological system. [Kopelman et al.]
The small size of the optical fibers allow sensing intracelular
intercelular physiological and biological parameter in micro-
environment.

21. Two kind of fabrication methods for
optical fiber tips
 Heat and Pull Method
 Chemical Etching

23. Applications of Nanobiosensors
Biological
– 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.

24. Environmental Applications
– Detection of environmental pollution and toxicity
– Agricultural monitoring
– Ground water screening
– Ocean monitoring

25. Future Application
Cancer Monitoring
• Nanobiosensors play a very important role for early cancer detection in body
fluids.
• The sensor is coated with a cancer-specific antibody or other biorecognation
ligands. The capture of a cancer cell or a target protein yields electrical, optical or
mechanical signal for detection.
• [Professor Calum McNeil detection of cancer proteins that cause MRSA]
Identification of Biomarkers
↓
Validation of Cancer Biomarkers
↓
Cancer Biomarkers
↓
Ligands / Probes Developments
↓
Cancer Diagnostics Biosensor ← Detector
↓
Point of Care Cancer Diagnostics

26. References
• Nanotechnology Online, Vol.3, 1-14.
• Rogers, K.(2006). Recent advances in biosensor
techniques for environmental monitoring. Analitica
Chimica Acta. Vol. 568(1-2), 599-624.
• Li, C. (2005).Complementary Detection of Prostate-
Specific Antigen Using In2O3 Nanowires and
Carbon Nanotubes. Journal of the American
Chemical Society, Vol.127(36), 12484-12485.