Amperometric glucose biosensor based on glucose oxidase immobilized in poly(o-phenylenediamine) layer

Amperometric biosensors for glucose were prepared by immobilization of glucose oxidase (GOx) into a poly(o-phenylenediamine) (POPD) film by simple one-step electropolymerization procedure. Sensors based on POPD-GOx membrane show a diminished sensitivity to ascorbate interference. The rejection of ascorbate may be additionally increased by placing an additional layer of POPD between platinum electrode and POPD-GOx composite layer. By combination of a few POPD- and POPD-GOx layers, glucose biosensors were prepared, characterised by sensitivity of 0.2 to 0.7 mu A mM(-1) cm(-2), linear range of response within 8 to 14 mM of glucose, response time of 4 to 8 s, and ascorbate retention up to 95%. The additional layer of Prussian blue (PB) was also placed between substrate electrode and enzyme-containing layer. The resulting PB/POPD-GOx biosensor can be operated by both an anodic manner at a potential of +0.4 to +0.6 V, and a cathodic manner at a potential of +0.2 to -0.2 V vs. Ag/AgCl. The combination of PB layer ensuring electrode operation at low potential values, and of an interference-rejecting POPD layer enables to decrease drastically the influence of ascorbate interference. (C) 1999 Elsevier Science S.A. All rights reserved.