Biosensor

1. Pharmaceutical Biotechnology
(BP605T)
By: Alok Kumar Soni (Asst Prof)
Unit I
Part C: Biosensors-Working and applications of
biosensors in Pharmaceutical Industries

2. A sensor is an object whose purpose is to detect events or changes
in its environment, and then provide a corresponding output.
e.g Pressure sensor, Ultrasonic sensor , Humidity Sensor , Gas Sensor ,
Motion Sensor ,Biosensor , Acceleration sensor , Displacement sensor etc.
A transducer is a device that converts one form of energy to
another.
e.g pressure sensor might detect pressure (a mechanical form of
energy) and convert it to electrical signal for display at a remote
gauge.
A sensor is a type of transducer.
What is sensor ?

3. Accuracy (how much accurate reading it produces)
Precision (how close is the measured value to the true value)
Resolution ( smallest incremental change in the input that will
produce a detectable change in the output)
Sensitivity (ratio of incremental output to incremental input)
Selectivity and specificity (depends on the unwanted signals)
Sensor characteristics

4. The role of biological and biochemical processes is paramount in
clinical diagnostics, medical applications, bioreactors, food quality
control, agriculture, control of industrial waste water, mining, and the
military defense industry.
the conversion of biological data to measurable electrical signals is
currently a tedious and time-consuming process
 In this context, biosensors have been explored widely because they
can be used to convert a biochemical process into a measurable signal
The basic difference between the biosensor and physical/chemical
sensor is that its recognition element is biological

5. Biosensor is an analytical device for the detection of an analyte that combines a
biological component with a physico chemical detector
Professor Leland C Clark Jnr is known as the father
of the biosensor . On 15 April 1956 the biosensor
that he invented was named after him as “Clark
electrode”
1977 Karl Cammann coined the term “biosensor

6. Components
The biocatalyst (a) converts the substrate to product. This reaction is
determined by the transducer (b) which converts it to an electrical signal. The
output from the transducer is amplified (c), processed (d) and displayed (e).

10. Principles of detection
Photometric
Electrochemical
Ion channel switch
Others…,like piezoelectric, thermometric etc
photometric
Many optical biosensors based on the principle of surface plasma
resonance(SPR)
This utilises a property of gold & other materials specifically that a thin layer of
gold on a high refractive index glass surface can absorb light producing
electron waves (surface plasmons) on the glass surface.
This occurs only at a specific angle & wave length of incident light and is highly
dependent on the surface of gold , such that binding of a target analyte to a
receptor on the gold surface produces a measurable signal

12. The Interferometric Reflectance Imaging Sensor (IRIS) was developed by the Unlu
research group at Boston University for the purpose of label-free biosensing.
Practical uses of this device include the detection of bacterial and viral
infections in underdeveloped countries.
When pathogen specific growth factors are introduced into a microarray, only
spots with the targeted pathogens will grow and increase in concentration.
In turn, this dictates a change in the reflected intensity compared to pre-
growth. Thus, by measuring how reflectance changes over time, unknown
pathogens and their growth rates can be easily characterized and identified.
All biosensors usually involve minimal sample preparation as the biological
sensing component is highly selective for the analyte concerned
They enable the detection of analyte at levels previously only achieved by
HPLC & MS & with out rigorous sample preparation

14. Ion channel switch
An Ion Channel Switch (ICS) biosensor can be created using gramicidin, a
dimeric peptide channel, in a tethered bilayer membrane. One peptide of
gramicidin, with attached antibody, is mobile and one is fixed.
Capture molecules such as antibodies can be bound to the ion channel so that
the binding of the target molecule controls the ion flow through the channel.
This results in a measurable change in the electrical conduction which is
proportional to the concentration of the target
.

20. Of these biosensors, the most publicized is
the optical biopsy sensor developed by Tuan
Vo-Dinh in collaboration with medical
researchers at Thompson Cancer Survival
Center in Knoxville.
This sensor can tell whether a tumor in the
esophagus is cancerou s or benign.
In the past, determining accurately whether a
patient has cancer of the esophagus has
required surgical biopsy.
However, laser-based fluorescence method
has eliminated the need for biopsy, reducing
pain and recovery time forpatients.
Laser light of the appropriate wavelength is directed to the inner surface of the
esophagus by means of a fiber-optic device that is swallowed by the patient.
The epithelial cells and tissue inside the esophagus fluoresce when excited by
the laser light. When the esophagus interior is illuminated with blue light [410
nanometers (nm)], the normal tissue emits light at wavelengths different from
those emitted by the cancer cells

21. A chip on our fingertip may someday measure and transmit data on
body temperature.
An array of chips attached to our body may provide additional
information on blood pressure, oxygen level, and pulse rate.