Immobilization and Direct Electrochemistry of Horseradish Peroxidase on Large Cage-Like Mesoporous Silica FDU-12

Abstract

We report on a direct electron transfer and bioelectrocatalysis of horseradish peroxidase (HRP) immobilized in mesoporous silica FDU-12 with three-dimensional (3D) large cages and entrances. UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and impedance spectroscopy were used to prove the interaction between HRP and FDU-12. Results from cyclic voltammetry show that immobilized HRP can undergo a direct quasi-reversible electrochemical reaction. Its formal potential, E0′, is -0.325 V in a phosphate buffer solution (PBS, pH 6.9) and this is almost independent of the scan rate from 40 to 300 mV·s -1. The experimental results also demonstrate that the immobilized HRP retains its bioelectrocatalytic activity for the reduction of H2O2. Furthermore, the electrode can be stored at 4 °C for several weeks without any loss of enzyme activity. Thus, FDU-12 is a novel matrix for realizing a direct electron transfer of various proteins and enzymes and the preparation of electrodes for the third biosensors.