Immobilization of hemoglobin on zirconium dioxide nanoparticles for preparation of a novel hydrogen peroxide biosensor

Direct electrochemistry and thermal stability of hemoglobin (Hb) immobilized on a nanoineter-sized zirconium dioxide (ZrO2) modified pyrolytic graphite (PG) electrode were studied. The immobilized Hb displayed a couple of stable and well-defined redox peaks with an electron transfer rate constant of (7.90 +/- 0.93) s(-1) and a formal potential of -0.361 V (-0.12 V versus NHE) in 0.1 M pH 7.0 PBS. Both nanometer-sized ZrO2 and dimethyl sulfoxide (DMSO) could accelerate the electron transfer between Hb and the electrode. Spectroscopy analysis of the Hb/ZrO2/DMSO film showed that the immobilized Hb could retain its natural structure. This modified electrode showed a high thermal stability up to 74 degreesC and an electrocatalytic activity to the reduction of hydrogen peroxide (H2O2) without the aid of an electron mediator. The electrocatalytic response showed a linear dependence on the H2O2 concentration ranging from 1.5 to 30.2 muM with a detection limit of 0.14 muM at 3sigma. The apparent Michaelis-Menten constant K-M(app) for H2O2 sensor was estimated to be (0.31 +/- 0.02) mM, showing a high affinity. (C) 2003 Elsevier B.V. All rights reserved.