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

Abstract

α-zirconium phosphate nanosheets (ZrPNS) derived via the delamination of layered α-zirconium phosphate (α-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 film 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 (GCE), showing a pair of well-defined, nearly reversible cyclic voltammetry (CV) peaks for the HRP heme FeIII/FeII redox couple. The average surface concentration (Γ⁎) of electroactive HRP in HRP–ZrPNS film was estimated to be 1.35×10−10 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 1.3×10−6 to 1.6×10−2 M with a correlation coefficient of 0.9997.