Comparative Studies on Enzyme Activity of Immobilized Horseradish Peroxidase in Silica Nanomaterials with Three Different Shapes and Methoxychlor Degradation of Vesicle-Like Mesoporous SiO2 as Carrier

: In the present work, three differently shaped mesoporous silica nanoparticles, spherical nano-SiO2, tubular mesoporous SiO2 and vesicle-like mesoporous SiO2 (VSL), were prepared and used to immobilize Horse radish peroxidase (HRP), and their enzyme's activity was also evaluated. It was found that the VSL immobilized HRP displayed higher specific activity than free enzyme and other two differently shaped silica immobilized HRP. After immobilization, the thermal stability, pH tolerance resistance and storage stability on vesicle-like SiO2 were studied as well. In addition, the kinetic constants Km and Vmax for HRP were significantly altered by immobilization. The affinity for HRP towards its substrate increased (with decreasing Km), leading to enhanced catalytic efficiency (with increased Vmax). Moreover, the reusability for degradation of methoxychlor (MXC) by VSL immobilized enzyme was studied and its degradation products were detected by GC-MS and NMR analysis.