The document discusses biosensors, emphasizing enzyme-based biosensors, which combine enzymes with transducers to detect target analytes. It details various types, including electrochemical, optical, thermistor, and piezoelectric biosensors, along with their applications in COVID-19 detection and fields like medicine, food safety, and environmental monitoring. The conclusion highlights the advantages of enzyme biosensors over traditional methods, such as improved sensitivity and real-time analysis capabilities.

1. ENZYMEPROBES–
BIOSENSORS
Parmar Amita
Roll No. 30
M.Sc. Microbiology Sem 3
Department of Biosciences, VNSGU

2. Outline
• Introduction of biosensors
• Basic components of enzyme biosensors
• Types of biosensors
• Approaches in Improving Enzyme Usage in Biosensors
• Enzyme biosensors for COVID -19 detection in the air
• Applications of biosensors
• Conclusion
• References & bibliography
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3. INTRODUCTION
• What is a Biosensor ?
A biosensor is an analytical device, used
for the detection of a chemical substance,
that combines a biological component
with a physicochemical detector.
The term ‘biosensor’ was introduced by
Cammann in 1977.
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4. The first 'true' biosensor was
developed by Leland C. Clark, Jr in
1956 for oxygen detection in blood .
He is known as the father of
biosensors and his invention of the
oxygen electrode bears his name:
'Clark electrode’ .
FATHEROFBIOSENSORS
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5. • A bioreceptor that is an immobilized
sensitive biological element
recognizing the analyte.
• A transducer is used to convert
(bio)chemical signal resulting from the
interaction of the analyte with the
bioreceptor into an electronic one.
Abiosensorisadevice
composedoftwoelements :
(General structure of a biosensor)
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6. TYPESOFBIOSENSORS
• Based on Bioreceptors :
Enzyme biosensor
Microbial Biosensor
Affinity biosensor
5

7. An enzyme biosensor is an
analytical device that combines
an enzyme with a transducer to
produce a signal proportional to
target analyte concentration.
EnzymeBiosensors:
6

8. Enzyme based biosensors are divided into several categories based on the
transducer types :
(1)
Electrochemical
Biosensors
(2)
Enzymes-based
optical biosensors
(3)
Enzyme based
Thermistors
(4)
Enzyme-based
Piezoelectric
biosensors
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9. (1) Electrochemical sensors :
They are one of the most extensively used
biosensors whose working mechanisms
are based upon the electrochemical
properties of transducers and analytes .
8

10. (A typical design of an enzyme modified
electrochemical biosensor)
The majority of the current glucose biosensors are of the
electrochemical type. The use of electrochemical biosensors provides
advantages such as simplicity, rapidity, low cost, and high sensitivity.
(Glucose oxidase Biosensor)
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11. The optical transducers of enzyme-based biosensors measure changes in optical
properties such as fluorescence intensity, light absorption, reflectance,
chemiluminescence, reflective index, and Raman scattering, resulting from the
interaction of a biocatalyst with a target analyte.
One of the earliest examples of an optical biosensor for clinical applications is a
test strip for glucose in urine, commercialized in 1957 .
The working principle of the sensor utilized a cellulose pad coimmobilized with
GOx and peroxidase in a cascade manner.
(2) Enzymes-based optical biosensors :
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12. 11
The second immobilized
peroxidase enzyme then catalyzes
the reaction between the formed
hydrogen peroxide and
orthotolidine, to yield a deep blue-
colored product.
The change in blue color could be
visually determined by the eye, and
was used as a semiquantitative
measurement of glucose
concentration in urine.
 Firstly, GOx catalyzes the oxidation of glucose to gluconic acid and
hydrogen peroxide.

13. Almost all enzymatically catalyzed reactions are exothermic, which may be used as
a basis for measuring the rate of reaction and the analyte concentration.
It measures changes in temperature by molar enthalpy change (∆H) in the form of
electrical signals .
Thermistor-based calorimeters, popularly known as enzyme thermistors (ET), use
thermistors to measure electrical changes due to changes in temperature following
a biocatalytic reaction, and this system is especially exploited for quantification
purposes.
(3)Enzyme-Based Thermistors
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14. The thermometric enzyme-linked
immunosorbent assay (TELISA),
for the assay of endogenous and
exogenous compounds in
biological fluids has been
developed by Mattiasson et al.
The figure shows the schematic
illustration of the TELISA method
for both direct competitive (A)
and sandwich (B) formats.
13
(Schematic representation of the thermometric enzyme-linked
immunosorbent assay (TELISA) method)

15. (4) Enzyme-Based Piezoelectric Biosensors
● The most common type of
piezoelectric biosensor is
quartz crystal microbalance
(QCM), which is able to
determine nanograms of
material.
● The sensor consists of a thin
wafer of quartz-sensing
crystal plated with metallic
electrodes on either sides of
the crystal by means of vapor
deposition.
14
(Schematic representation of the electro spun nanofibrous PLGA/Fullerene-
C60-modified QCM for the real-time monitoring of gluconic acid)

16. ● Biological Modification
(1) Site-Directed Mutagenesis
(a) Enzyme Amino Acid Substitution
(b) Enzyme Amino Acid Removal
(c) Non-Natural Amino Acid Incorporation
(d) Enzymatic Addition of a Genetic Tag
(2) Fusion Protein Technology
● Chemical Modification
(1) Site-Specific Chemical Modification
(2) Nonspecific Modification of the Enzyme Surface
(3) Chemical Cross-Linking
(4) Use of Polymers
● Multi-Enzyme System
ApproachesinImprovingEnzymeUsageinBiosensors
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17. A team of researchers from Empa (Zürich,
Switzerland) and ETH Zurich (Zürich, Switzerland)
usually work on measuring, analysing and reducing
airborne pollutants such as aerosols and artificially
produced nanoparticles,
has succeeded in developing a novel sensor for
detecting the new coronavirus that could be used to
measure the concentration of the virus in the
environment.
ENZYMEBIOSENSORSFORCOVID-19DETECTIONINTHEAIR:
16

18. (Schematic structure of SARS-Cov-2 and its possible targets for diagnosing)
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19. APPLICATIONSOFBIOSENSORS
1) Applications in Medicine and Health as diagnostic
Tools
2) As Analytical Tools for the Assessment of Food
Quality and Food Safety
3) Applications in Pollution Control
4) Applications in defence
5) Application in agriculture and so on.
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20. Enzyme-based biosensing has proven to be a valuable technique for the
qualitative and quantitative analysis of a variety of target analytes in
biomedicine, environmental, food quality control, agricultural, and
pharmaceutical industry.
In comparison with conventional analytical methodologies, enzyme-based
biosensors offer significant benefits, such as miniaturization, real-time
diagnosis capability, high sensitivity and specificity, minimum sample
preparation, and high-throughput, bedside clinical testing and portability.
In the future, biosensors will be widely used in many fields, such as food
detection, medical care, disease diagnosis, environmental monitoring,
fermentation industry, and so on.
CONCLUSION
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21. REFERENCES:
• Hoang Hiep Nguyen 1,2,†, Sun Hyeok Lee 1,2,†, Ui
Jin Lee 1,3, Cesar D. Fermin 4 and Moonil Kim.
Immobilized Enzymes in Biosensor Applications.
Sensors 2020, 20(6), 1721
• www.empa.ch , A new biosensor for the COVID-19
virus
• Anastasios Economou , Steve Karapetis , Georgia-
Paraskevi Nikoleli , Dimitrios P. Nikolelis . Enzyme-
based Sensors . Advances in Food Diagnostics
(pp.231-250)
• Rachel Samson1,2 · Govinda R. Navale1,2 ·
Mahesh S. Dharne . Biosensors: frontiers in rapid
detection of COVID-19. 3 Biotech 10, pp. 385
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22. THANKYOU
MAYYOUALLHAVEAGREATDAY!