Direct electrochemistry and electrocatalysis of horseradish peroxidase in α-zirconium phosphate nanosheet film

alpha-zirconium phosphate nanosheets (ZrPNS) derived via the delamination of layered alpha-zirconium phosphate (alpha-ZrP) have been proven to be efficient support matrixes for the immobilization of horseradish peroxidase (HRP). X-ray powder diffraction (XRD) results revealed that ZrPNS in HRP-ZrPNS him remained unorderly structured for the effect of HRP. Fourier transform infrared (FTIR) spectra results revealed that HRP remained the secondary structure in HRP-ZrPNS film. The direct electrochemistry of HRP was realized in HRP-ZrPNS film on a glassy carbon electrode (CCE), showing a pair of well-defined, nearly reversible cyclic voltammetry (CV) peaks for the HRP heme Fe-III/Fe-II redox couple. The average surface concentration (Gamma*) of electroactive HRP in HRP-ZrPNS film was estimated to be 1.35 x 10(-10) mol cm(-2). which indicated a high loading of enzyme molecules in HRP-ZrPNS film. Based on these, a third generation reagentless biosensor was constructed for the determination of hydrogen peroxide (H2O2). The response time of the biosensor was less than 3 s, and the linear response range of the biosensor for H2O2 was from 1.3 x 10(-6) to 1.6 x 10(-2) M with a correlation coefficient of 0.9997. (C) 2008 Elsevier B.V. All rights reserved.