BIOSENSORSBIOSENSORS

Prepared By :

INTRODUCTIONINTRODUCTION• What Is a Biosensor?• Biosensor = bioreceptor + transducer. • The bioreceptor is a biomolecule that recognizes

the target analyte whereas the transducer converts the recognition event into a measurable signal.

• Enzyme is a Bioreceptor • Requirements for Sensors

Need for Biosensor• Diagnostic Market The current climate of prevention the need for detection

at increasingly lower limits is increasing in many diverse areas

• Clinical Testing clinical testing is one of the biggest diagnostic markets

clinical testing products market in excess of 4000 million US$

in the 1990s • Other Markets

The medical arena (Technical Insights Inc.) with veterinary and agricultural applications

• SpecificityWith biosensors, it is possible to measure specific

analytes with great accuracy. • Speed

analyte tracers or catalytic products can be directly and instantaneously measured • Simplicity

receptor and transducer are integrated into one single sensor& the measurement of target analytes without using reagents is possible• Continuous monitoring capability

Biosensors regenerate and reuse the immobilized biological recognition element

Applications of Biosensor• Health Care

– Measurement of Metabolites– Market Potential– Diabetes – Insulin Therapy– Artificial Pancreas

• Industrial Process Control– Bioreactor Control

• Military Application• Environmental Monitoring

– Air and Water Monitoring

Bioreceptor Molecules

• Enzymes

Enzymes act as catalysts for biochemical reactions occurring in the cell

• AntibodyAntibodies constitute about 20% of the total

plasma protein and are collectively called immunoglobulin

• Receptor Protein Receptor proteins having specific affinity for

hormones, antibodies, enzymes

• Other Possibilities

Transducers

• Conventional Transducers • Piezoelectric Transducers • Coniductimetry • Capacitance Measurement • Thermometry • Enzyme Thermistor • FET as a Transducer

Growth of Biosensor

• Biosensor Configurations

• Discriminative Membrane

• Sensitivity Requirements

• Immunoassay

• DNA Probe

• Evolution of Biosensors

Receptors • Receptors at Membrane

Biological receptors are protein molecules most of them are bound to the cell membrane

• Hormone Receptors Many hormones released into the blood do not

penetrate the cell membrane but react with specific receptors at the cell surface

• Smell Receptor taste and olfactory receptors are typical examples of

this biospecific recognition process

• Light Receptor

Types of biosensor• Glucose Biosensor

• Amperometric BiosensorGlucose biosensor using glucose oxidase is used as an example

• Potentiometer BiosensorExamples of Potentiometric Biosensor

Penicillin biosensor Glucose biosensor

Urea biosensor

Design Variables• Immobilization Methods

(1) adsorption

(2) entrapment

(3) covalent coupling

(4) cross-linking

• Change in Conformation • Change in Microenvironment• Non-Uniform Distribution• Reaction and Diffusion

Future Prospects

• Data Processing and Pattern Recognition

• Micro Instrument

• Molecular Electronics

• Multi-Disciplinary Nature

CONCLUSION

Biosensors consist of bio-recognition systems, typically enzymes or binding proteins, such as antibodies, immobilized onto the surface of physico-chemical transducers

Disadvantages• They cannot be steam sterilized   • They react with the product  

• And are oversensitive