Tham khảo tài liệu 'new perspectives in biosensors technology and applications part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 412 New Perspectives in Biosensors Technology and Applications electrode whereupon the enzyme becomes embedded into the polymer matrix. The incorporation of the enzyme into the matrix is often promoted through electrostatic interactions. Numerous enzymes have been incorporated into electropolymerized films Bartlett and Cooper 1993 . In many cases conductive polypyrrole PPy has been used as a polymer matrix. This choice relates to the fact that pyrrole can be electropolymerized at low oxidation potentials in aqueous solutions at neutral pH which is compatible with a wide range of biological molecules. Polypyrrole has proven effective at electrically wiring the enzymes and CNTs to the underlying electrode. During the fabrication of such biosensors CNTs bearing carboxylic groups are often used due to their ability to function as an anionic dopant in the matrix. Recently a simple method to immobilize AChE on PPy and polyaniline PAn copolymer doped with multi-walled carbon nanotubes MWCNTs was proposed Du et al 2010 . The synthesized PAn-PPy-MWCNTs copolymer presented a porous and homogeneous morphology which provided an ideal size to entrap enzyme molecules. The surface hydrophilicity was improved greatly after forming a complex structure instead of a separate layer. It provided an excellent environmental and chemical stability around the enzyme molecule to stabilize its biological activity to a large extent resulting in a stable AChE biosensor for screening of organophosphates exposure. MWCNTs promoted electrontransfer reactions at a lower potential and catalyzed the electro-oxidation of thiocholine thus increasing detection sensitivity. Based on the inhibition of OPs on the AChE activity using malathion as a model compound the inhibition of malathion was proportional to its concentration ranging from to pg mL and from 1 to 25 pg mL with a detection limit of ng mL. Advantages of the electropolymerization approach include the good control over the film .
