Hydrogen peroxide biosensor based on the bioelectrocatalysis of horseradish peroxidase incorporated in a new hydrogel film

Horseradish peroxidase was immobilized on a glass carbon electrode by poly (N-isopropylacyamide-co-3-methacryloxy-propyltrimethoxysilane) (PNM). Horseradish peroxidase entrapped in the PNM film exhibited a pair of well-defined, quasi-reversible cyclic voltammetric peaks at about -0.36 V versus a saturated calomel electrode (SCE) in pH 7.0 buffer solution, corresponding to hemeFe(III) +e -> hemeFe(II). Some electrochemical parameters were calculated by performing nonlinear regression analysis of square wave voltammetry (SWV) experimental data. Fourier transform infrared (FTIR) spectra suggested that horseradish peroxidase entrapped in the PNM film retained the secondary structure. Hydrogen peroxide could be reduced by the catalysis of the entrapped horseradish peroxidase without any mediator. The reagentless hydrogen peroxide sensor had a fast response of less than 2.5 s with linear range of 0. 19-1.35 mu M with a detection of 4.75 x 10(-8) mol L-1. The sensitivity of the sensor for H2O2 was 0. 62 A mol(-1) cm(-2). The activation energy for enzyme reaction was calculated to be 14.84 kJ mol(-1). (c) 2007 Published by Elsevier B.V.