Direct electrochemistry and electrocatalysis of myoglobin immobilized in zirconium phosphate nanosheets film

Myoglobin (Mb) is incorporated on a novel matrix-zirconium phosphate nanosheets (ZrPNS) and immobilized at a glassy carbon electrode surface. UV-vis spectra and electrochemical measurements show that the matrix is well biocompatible and can retain the bioactivity of immobilized Mb. The direct electron transfer between Mb and electrode exhibits a couple of well-defined redox peaks. The cathodic and anodic peaks are located at -0.340 and -0.280V vs. Ag/AgCl, respectively. The ZrPNS can improve the electron transfer between Mb and electrode with an electron transfer constant of 5.6 s(-1). Meanwhile, the catalytic ability of the protein toward the reduction of H2O2, 02, NaNO2, trichloroacetic acid (TCA) is also studied and a third-generation biosensor is subsequently fabricated. The linear range of biosensor to H2O2 is from 8 x 10(-7) to 1.28 x 10(-5) M with the limit detection of 1.4 x 10(-7) M. The small apparent Michaelis-Menten constant (34 mu M) suggests that Mb/ZrPNS film performs good affinity with H2O2. The biosensor also exhibits acceptable stability and reproducibility. This work paves a way to develop other biologic active materials in this kind of nanosheets for constructing novel biosensors. (c) 2007 Elsevier B.V. All rights reserved.