Elaboration of a new hydrogen peroxide biosensor using microperoxidase 8 (MP8) immobilized on a polypyrrole coated electrode

A novel strategy for elaborating a new biosensor for hydrogen peroxide has been developed by combining the known properties of microperoxidase 8 (MP8) as an oxidation catalyst, and the interesting properties of conducting polypyrrole as a supporting matrix to allow a good bioelectrochemical interface and a large dispersion of MP8 on the modified glassy carbon electrode. MP8 was immobilized into the conducting polypyrrole by entrapment during the electrochemical polymerization, and the modified electrode was characterized both by electrochemical and FT-IR measurements. We demonstrated that MP8 could be immobilized into polypyrrole and could undergo an efficient electron transfer. The obtained modified electrode showed a high catalytic activity toward H2O2 without the need for an electron mediator. A linear calibration curve was obtained by amperometric measurement at a potential of -0.1 V/ECS for concentrations of H2O2 ranging from 1 to 10 mu M. The detection limit obtained was 1 nM which constituted a real improvement, by about three orders of magnitude, when compared to the values reported for other systems using an electrochemical detection. (c) 2007 Elsevier B.V. All rights reserved.