Enzyme based Biosensors

Biosensors are the analytical device that are used to measure the concentration of analye , these type of biosensors are made with conjugation of enzymes as a biological eliment to quantify a (bio)chemical substance / analyte are reffered to as Enzyme-probe Biosensors .
Biosensors are of many types but focusing on Enzyme biosensors there are 4 main types which are briefly described in this power point presentation .

1. ENZYME PROBES – 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 1

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. 2

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’  . FATHER OF BIOSENSORS 3

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. A biosensor is a device composed of two elements : (General structure of a biosensor) 4

6. TYPES OF BIOSENSORS 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. Enzyme Biosensors : 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 7

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) 9

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 : 10

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 12

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 Approaches in Improving Enzyme Usage in Biosensors 15

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. ENZYME BIOSENSORS FOR COVID -19 DETECTION IN THE AIR : 16

18. ( Schematic structure of SARS-Cov-2 and its possible targets for diagnosing) 17

19. APPLICATIONS OF BIOSENSORS Applications in Medicine and Health a s diagnostic Tools As Analytical Tools for the Assessment of Food Quality and Food Safety Applications in Pollution Control Applications in defence Application in agriculture and so on. 18

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 19

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 20

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