Enzyme Technology

Biochips - The Biological Computer
Biochip is the result of marriage of microchips business with biotechnology. In future, there is the possibility of developing biological computers.

Until the development of silicon microchips, setting up of computers was very costly and space occupying. But recently, one can have a computer to be fit on desk top. These affordable prices are mainly due to the development of silicon microchips which brought into a rapid revolution in technology. Further reduction in size of computers and improvement in computing powers will not be possible because the silicon microchip technology has certain limitations as below :

(i)    There is inherent limit beyond which circuits cannot be squeezed onto a silicon chip. For example the width of the circuit cannot be shorter than the wavelength of light. Light is used to etchout circuits during the manufacturing of silicon chips.
(ii)  Close placing beyond a limit of many electrical circuits on the same microchip results in 'electron tunnelling' which creates short circuits ruining the whole system.
(iii) After cramming together of a large number of circuits, heat is generated by the electric current. This may cause total failure of the system.

Principles of Biochips
One of the important features of macromolecules (e.g. proteins) is their self shaping into predetermined three dimensional structure. This property of proteins helps in biochip designing because the circuits can be crammed around three dimensional protein structure. While designing the biochips, a semiconducting organic molecule is inserted into a protein frame work; the whole unit is fixed onto a protein support (Fig. 17.11). In biochips the electrical signals can pass through the semiconducting organic molecule in the same way as in silicon microchip. It has many advantages over silicon microchip as below :
  Diagrammatic representation of biochip.  

Fig. 17.11. Diagrammatic representation of biochip.


(i)    In biochip the width of electrical circuits should not be more than that of one protein molecule which is smaller than the smallest silicon microchip.
(ii)   The problem of electron tunnelling would be to certain extent less acute in biochip than silicon microchip.
(iii)  The protein molecule possess less electrical resistance, therefore, less heat will be generated during the course of production of electrical signals. Consequently, a large number of circuits can be placed together as it is not possible in silicon microchips.
» Microorganisms
» Properties of enzymes

» Presence of species specificity

» Variation in activity and stability

» Substrate specificity

» Activation and inhibition
» Methods of enzyme production

» Isolation of microorganisms, strain development and preparation of inoculum 

» Medium formulation and preparation

» Sterilization and inoculation of medium, maintenance of culture and fluid filtration

» Purification of enzymes
» Immobilization of enzymes

» Advantages of using immobilized enzymes

» Methods of enzyme immobilization

» Adsorption

» Covalent bonding (Ionic bonding)

» Entrapping

» Cross linking

» Encapsulation

» Effects of enzyme immobilization on enzyme stability
» Enzyme engineering
» Application of enzymes

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» Biosensor

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» Applications of biosensor
» Biochips

» Principles of Biochips

» Application of Biochips

Application of Biochips
(i)    Biochips can respond to natural nerve impulses making looks more natural when implanted into the artificial limbs.
(ii)   It is also possible that they can also be used as a heart-heat regulator. This will solve the problems of users of costly pace makers.
(iii)  It can also help blind or deaf. It can be designed in such a way that can sense light and sound, and convert them to electrical signals. These signals after reaching brain stimulate sight and sound,
(iv)  It can be designed in accordance with the need of military. It can keep immune to the disastrous effects of electromagnetic waves which are generated due to nuclear explosion.