BIOSENSORS

1. BIOSENSORS • A biosensor is an analytical device which converts a • biological response into an electrical signal. • The term 'biosensor' is often used to cover sensor • devices used in order to determine the concentration • of substances and other parameters of biological • interest even where they do not utilise a biological • system directly. • Research and development in this field is wide and • multidisciplinary, spanning biochemistry, bioreactor • science, physical chemistry, electrochemistry, • electronics and software engineering. BIOMATERIALS

2. BIOSENSORS • A successful biosensor must possess at least some of the following beneficial features: • The biocatalyst must be highly specific for the purpose • of the analyses,be stable under normal storage • conditions. • The reaction should be as independent of such • physical parameters as stirring, pH and temperature • as is manageable. • If the reaction involves cofactors or coenzymes these • should, preferably, also be co-immobilised with the • enzyme. BIOMATERIALS

3. BIOSENSORS • Schematic diagram showing the main components of a biosensor. 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). BIOMATERIALS

4. BIOSENSORS • The key part of a biosensor is the transducer • which makes use of a physical change • accompanying the reaction. • This may be the heat output by the • reaction,changes in the distribution of charges • causing an electrical potential to be • produced,movement of electrons produced in a • redox reaction,light output during the reaction or a • light absorbance difference between the reactants • and products,or effects due to the mass of • the reactants or products. BIOMATERIALS

5. BIOSENSORS • There are three so-called 'generations' of biosensors; • First generation biosensors where the normal product of the reaction diffuses to the transducer and causes the electrical response. • Second generation biosensors which involve specific 'mediators' between the reaction and the transducer in order to generate improved response. • Third generation biosensors where the reaction itself causes the response and no product or mediator diffusion is directly involved. BIOMATERIALS

6. BIOSENSORS • The electrical signal from the transducer is often low • and superimposed upon a relatively high and noisy • baseline. • The signal processing normally involves subtracting a • 'reference' baseline signal, derived from a similar • transducer without any biocatalytic membrane, from • the sample signal, amplifying the resultant signal • difference and electronically filtering (smoothing) out • the unwanted signal noise. BIOMATERIALS

7. BIOSENSORS • The relatively slow nature of the biosensor response • considerably eases the problem of electrical noise • filtration. • The analogue signal produced at this stage may be • output directly but is usually converted to a digital • signal and passed to a microprocessor stage where the • data is processed, converted to concentration units and • output to a display device or data store. BIOMATERIALS

8. TISSUE ENGINEERING • Tissue engineering / regenerative medicine is an • emerging multidisciplinary field involving biology, • medicine, and engineering that is likely to revolutionize • the ways we improve the health and quality of life for • millions of people worldwide by restoring, maintaining, • or enhancing tissue and organ function. • In addition to having a therapeutic application, where • the tissue is either grown in a patient or outside the • patient and transplanted, tissue engineering can have • diagnostic applications where the tissue is made in • vitro and used for testing drug metabolism and uptake, • toxicity, and pathogenicity. BIOMATERIALS

9. TISSUE ENGINEERING • Tissue engineering has been defined as "the use of • living cells together with extracellular components, • either natural or synthetic, in the development of • implantable parts or devices for the restoration or • replacement of biological function". • In other words, tissue engineering includes isolated • cells,tissue-inducing substances, and cells placed • within matrices. BIOMATERIALS

10. TISSUE ENGINEERING • Organs contains one or more tissues and tissues are made up of specific cells. • The three parts of tissue that regulate the performance of a cell are • The cells themselves • (ii)Non-soluble factors within the extracellular matrix (ECM) such as laminins,collagens,and other molecules • (iii)Soluble factors such as cytokines, hormones, nutrients, vitamins, and minerals. BIOMATERIALS

11. TISSUE ENGINEERING • In tissue engineering, there are several steps, which need be considered to accomplish a specific goal.These steps include: • cell isolation • cell culture • scaffold material choice • cell scaffold co-culture studies • implantation in animals • human trials BIOMATERIALS

12. TISSUE ENGINEERING • Thus, tissue-engineering procedure can be divided into two broad categories • in vitro construction of tissue containing devices, • in vivo alteration of cell growth and function. BIOMATERIALS

13. TISSUE ENGINEERING • Tissue engineering has many applications like, it is used as • Implantable Devices - vascular grafts, bone and cartilage grafts • Extracorporeal devices - artificial liver and artificial pancreas • Cell production and Cell growth - skin cells, nerve • regeneration BIOMATERIALS

14. TISSUE ENGINEERING • Now a days absorbable materials like synthetic • polysters,polyvinyl alcohol etc are used in tissue • engineering to support tissue growth. • The tissues are grown on absorbable support. • As new tissues forms the absorbable material disappears. BIOMATERIALS

15. TISSUE ENGINEERING • Tissue engineering finds wide applications in the field of medicine. • The method of transplantation and reconstruction are of huge costs. • Tissue engineering provides substitutes that are less • expensive than the donor organs and leads to less • complications. BIOMATERIALS