BIOSENSOR TECHNOLOGY power point presentation

Biosensor technology

1. BT2255 MICROBIOLOGY
UNIT V :
INDUSTRIAL AND ENVIRONMENTAL
BIOTECHNOLOGY

2. REFERENCES (RF)
1. Talaron K, Talaron A, Casita, Pelczar And Reid. Foundations In
Microbiology, W.C.Brown Publishers, 1993.
2. Pelczar MJ, Chan ECS and Krein NR, Microbiology, Tata McGraw-Hill
Edition, New Delhi, India.
3. Prescott LM, Harley JP, Klein DA, Microbiology, 3rd Edition, Wm. C.
Brown Publishers, 1996.
Jeyamanikandan, B.Tech
Biotechnology
2

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BIOSENSOR TECHNOLOGY
TYPES OF BIOSENSORS AND ITS APPLICATIONS

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What are biosensors?
A biosensor is an analytical tool containing a biologically active material along
with a device that can convert a biochemical signal into a quantifiable electrical
signal.

5. Father of the Biosensor
Professor Leland C Clark Jnr
1918–2005
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6. Evolution of the Medical
Biosensor
Mid 1950’s - Leland C Clark invents an electrode that
measures dissolved oxygen in the blood of patients
undergoing surgery.
He surrounded a platinum electrode and reference
electrode with a plastic membrane permeable to
gases.
The voltage differential measured between the two
gave the rate at which the oxygen was being
diffused.
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7. Clark extended this electrode idea to include glucose sensors.
However these never made their way into routine patient care.
This was due to flaws in accuracy when clots formed around the
electrode.
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Components of Biosensors
Three components of biosensors
 Sensitive biological element
 Transducer
 Associated electronics

9. 1. LINEARITY Linearity of the sensor should be high
forthe detection of high substrate
concentration.
2. SENSITIVITYValue of the electrode response per
substrate concentration.
3. SELECTIVITYChemicals Interference must be
minimised for obtaining the correct result.
4.RESPONSE TIME Time necessary for having 95%
of the response.
Basic Characteristics of a
Biosensor
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Sensitive biological element/Receptor
element
It selectively recognizes a particular biomolecule through any reaction, specific
adsorption etc.
Eg. Enzyme, antibody, DNA sequence ,micro- organism, tissue, organelles, cell
receptors ,nucleic acids,etc.s

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Detection/Recognition
How do you specifically recognize the analyte?
Antibody Enzyme
Active site
Fab
Fc
Cell
Membrane receptors
Polymer/Hydrogel
Competitive binding

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Transducer/Detector element
BIOLOGICAL SIGNAL (ANALYTE+BIOLOGICAL ELEMENT) 
CONEVRTED TO ANOTHER SIGNAL
It works in a physico-chemical way like piezoelectric ,electrochemical,etc.

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Physico-chemical parameters
Heat output - calorimetric biosensors
Changes in distribution of charges changing the electric potential-
Potentiometric biosensors.
Movement of electrons in a redox reaction - amperometric biosensors.
Light output- optical biosensors.
Mass of the reactants or products- piezoelectric biosensors.

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Associated electronics /Signal processors
Responsible for the display of results in an user-friendly manner.

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AMPLIFIER PROCESSOR
DISPLAY
Electronically activated surface
BIOLOGICAL COMPONENT(ENZYME)
Analyte
Bound enzyme
PHYSICAL COMPONENT

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Principle of a Biosensor
BIOLOGICAL MATERIAL + ANALYTE
BOUND ANALYTE
BIOLOGICAL RESPONSE
ELECTRONIC RESPONSE
MEASUREMENT

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Biosensor breakdown
Analyte
Sample
handling/preparation
Detection
Signal
Analysis
Response

18. Biosensors
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19. Enzyme biosensors
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Electrodes detecting
gases such as O
2
, CO
2
,
NH
3 and various ionic
species are
commercially available

21. Application of immobilized enzymes
Bioremediation
For the removal/detoxification of contaminants
E.g. Polyphenol oxidase immobilized on chitosan coated membranes
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BASIS FOR CLASSIFICATION
 Biosensors are classified based on the following:
 SENSOR DEVICES
 TYPES OF BIOLOGICAL MATERIAL USED

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What are the types?
1.ELECTROCHEMICAL BIOSENSORS
 AMPEROMETRIC BIOSENSORS
 POTENTIOMETRIC BIOSENSORS
 CONDUCTIMETRIC BIOSENSORS

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2. THERMOMETRIC BIOSENSORS
3.OPTICAL BIOSENSORS
4.PIEZOELECTRIC BIOSENSORS
5.WHOLE CELL BIOSENSORS
6.IMMUNOBIOSENSORS

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ELECTROCHEMICAL BIOSENSORS
Devices based on measurements of electric current, ionic or conductance changes
carried out by bioelectrodes.

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AMPEROMETRIC BIOSENSORS
Based on movement of electrons.
Enzymatic reactionRedox reactionConstant voltage passes through the
electrodesDETERMINED

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ELECTRODES
Movement of electrons
SUBSTRATE
PRODUCT
AMPEROMETRIC BIOSENSORS

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Contd…
First generation
biosensors:
Direct transfer of
electrons released to
the electrode.
Second generation
biosensors:
A mediator like
ferrocenes is used.
It takes up the
electrons and then
transfer it to the
electrode.
AMPEROMETRIC BIOSENSORS

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BLOOD GLUCOSE BIOSENSOR
Four generations of blood
glucose meter
AMPEROMETRIC BIOSENSORS

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Contd..
Commercially available gluocose monitors rely on
amperometric sensing of glucose by means of glucose oxidase, which
oxidises glucose producing hydrogen peroxide which is detected by the
electrode.
AMPEROMETRIC BIOSENSORS

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AMPEROMETRIC BIOSENSORS

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POTENETIOMETRIC BIOSENSORS
Ion-selective electrodes are used like;
Hydrogen ion selective electrodes
Ammonia selective electrodes
CO
2
selective electrodes.
Limitations: enzymes- sensitive to ion concentrations like H
+

and NH
4
+
.
ISFET (Ion Selective Field Effective Transistor) can be used.

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Eg. ISFET biosensor for monitoring intramyocardial pH
during open heart surgery
OPEN HEART SURGERY
ISFET biosensor
POTENETIOMETRIC BIOSENSORS

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Conductimetric Biosensors
Here the electrical conductivity –altered– due to changes in ionic species
frequently.
Eg. Urea biosensor.
H
2N
C =O+3H
2O 2NH
4
+
+HCO
3
_
+OH
_
H
2
N
urease

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Two types of conductometric sensors with their corresponding equivalent
electrical circuit diagrams: (A) chemiresistor configuration typical for gas
sensing; (B) conductometric biosensor.

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THERMOMETRIC BIOSENSORS
Based on the production oh heat from biological reactions.
Otherwise known as thermal biosensors or calorimetric biosensors.

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THERMOMETRIC BIOSENSORS
productsubstrate
Insulated box
Heat exchanger
(aluminium
cylinder)
Thermistors
Immobilized
enzyme

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OPTICAL BIOSENSORS
Based on optical measurements like absorbance,flouresence,chemiluminescene
etc.
Eg. Fibre optic lactate biosensor
Optical biosensors for blood glucose.

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Fibre optic lactate biosensor
O
2
+lactate
Co
2+acetate+H
2O
FLUORESCENT LIGHT
EXCITATION LIGHT
polymethyl
methaacrylate
fluorescent
dye in silicone
ENZYME

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Whole cell biosensor
Useful for multistep reactions.
Employ live or dead microbial cells.

41. Three primary mechanisms
Based on biological oxygen demand (BOD)
Based on inhibition of respiration
Using genetically engineered microorganisms (GEMs)
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42. Based on BOD
Standard procedure(BOD
5)
5 DAY incubation of waste water sample with inoculum
To yield an end point measurement for O
2 Consumption
Uses indicator microorganisms interfaced to signal transducers
Measurement of rate of organic compound metabolism than the endpoint
•LIMITATIONS:
 Variability in calibration of the biosensor response.
Reason: specific microbial species have different requirement of substrates that
may not be in the sample.
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43. Inhibition of respiration
Inhibition of microbial respiration
Environmental pollutants
measured optically or electrochemically
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44. Using GEMs
GEMs-recognize and report the presence of pollutants.
Microorganisms modified with a plasmid construct
Genes that code for luciferase/galactosidase tagged after
strong promoters
Mechanism:
Recognition of the analyte by the promoter (i.e pollutant)
Reporting system activated
Presence of analyte results in synthesis of inducible
enzymes catalyse reactions resulting in production of
detectable products.
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45. List of organisms along with the analytes and the types of biosensors
OrgansimsOrgansims AnalyteAnalyte Type of biosensorType of biosensor
Escherichia coliEscherichia coli GlutamateGlutamate PotentiometricPotentiometric
Sarcina flavaSarcina flava GlutamineGlutamine PotentiometricPotentiometric
Proteus morganiiProteus morganii CysteineCysteine PotentiometricPotentiometric
Nitrosomonas sp.Nitrosomonas sp. AmmoniaAmmonia AmperometricAmperometric
Lactobacillus Lactobacillus
fermentifermenti
ThiamineThiamine AmperometricAmperometric
Lactobacillus Lactobacillus
arabinosusarabinosus
Nicotinic acidNicotinic acid PotentiometricPotentiometric
CyanobacteriaCyanobacteria HerbicidesHerbicides AmperometricAmperometric
Many organismsMany organisms BODBOD AmperometricAmperometric
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46. Eg. Whole-Cell Biosensors Based on Porous
Surfaces
Whole-cell biosensors
based on permeable
filter-like growth
substrates (first image
on the right) provide
the option to expose
the cell layer from
both sides to some
compound of interest.
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IMMUNO BIOSENSORS
•Works on the principle of immunological specificity between antigen and
antibody,that is coupled to either amperometric or potentiometric biosensors.

48. a. Direct binding of antigen to immobilized antibody
Ab
Ag
Ag
Ab
Ag
b. Antigen-antibody sandwiches (immobilized antigen
binds to antibody and then to a second antigen
+
+
+
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49. c. Antibody binds to immobilized antigen which gets
partially released by a competitive free antigen.
Ag-Ab
+
Ag
Ag
d. Immobilized antibody binds to free antigen and enzyme labeled antigen
Ab
+
Ag-Enz+Ag
Ab-Ag-Enz
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50.  Food Analysis:
Monitoring of fermentation products and estimation of ions.
To measure the odour and freshness of foods.
By using ATPase freshness of fish can be measured-ATP is not
found in spoiled fish.
Immobilized cholesterol oxidase system for measurement of
cholesterol concentrations in food.
 Study of biomolecules and their interaction
 Drug Development
 Crime detection
Application of Biosensor
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51. 
Medical diagnosis (both clinical and laboratory
use) and surgery:

Glucose biosensor

Blood gas monitoring-pH,CO2 and pO2

Mutagenicity of chemicals determined.

Environmental field monitoring:

Concentrations of pesticides and BOD can be measured
by using biosensors

Quality control

Industrial Process Control

Detection systems for biological warfare agents:

For detection of toxic gases,explosives and other
chemical agents used during war.

Manufacturing of pharmaceuticals.
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