Immobilization of Myoglobin on NiO Nanoparticles Matrix for Preparation of Novel Biosensor

Direct electrochemistry of myoglobin (Mb) immobilized on a nanometer-sized NiO nanoparticles matrix modified graphite electrode (GE) and preparation of novel hydrogen peroxide biosensor were studied. The immobilized Mb displayed a couple of stable and well-defined redox peaks with an electron transfer rate constant of 6.48 s(-1) and a formal potential of -0.340 V(vs . SCE) in 0.1 mol/L PBS (pH 7.0). The total surface concentration was 8.06 x 10(-10) mol/cm(2) Dimethyl sulfoxide (DMSO) could play an important role in the electron transfer between Mb and the electrode. Spectroscopy analysis of the Mb/NiO/DMSO film showed that the immobilized Mb could retain its natural structure. The electrocatalytic response showed a linear dependence on the H2O2 concentration ranging from 0.8 to 24 mu mol/L with a detection limit of 0.039 mu mol/L (3 sigma). The apparent Michaelis Menten constant K-Mapp for H2O2 sensor was estimated to be 0.21 mmol/L and the sensitivity was 417 mA cm(2) L/mol, which showed a high affinity.