BIOSENSORS BASED ON OXIDASES IMMOBILIZED IN VARIOUS CONDUCTING POLYMERS

The electrodeposited organic polymers polypyrrole, poly(N-methylpyrrole), poly(o-phenylenediamine) and polyaniline are compared as matrices for the immobilization of glucose oxidase in the preparation of amperometric glucose biosensors. Enzyme entrapment in the polymer layer is obtained by electrodeposition of polymers from solutions of monomers containing dissolved enzyme. For all examined sensors a useful and almost linear range of response to glucose is observed up to at least 20 mM of glucose. The best sensitivity of response is obtained for a glucose sensor made of poly(o-phenylenediamine) and polypyrrole. A linear response up to 20 mM glucose is also obtained in flow-injection measurements for a glucose/polypyrrole sensor. Poly(o-phenylenediamine) is also used for satisfactory immobolization of choline oxidase in the preparation of a choline sensor, whereas a lactate biosensor has been prepared by immobilization of lactate oxidase in polypyrrole.