Preparation of Functionalized Magnetic Silica Nanospheres for the Cellulase Immobilization

Cellulase was immobilized on functionalized magnetic silica nanospheres using glutaraldehyde as a cross-linking agent. The morphologies, structures and magnetic properties of this immobilized cellulase were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis and vibrating sample magnetometry. The properties of immobilized cellulase were investigated, including the amount of immobilized cellulase and its relative activity, stability and reusability. The results indicated that immobilized cellulase exhibited better resistance to high temperature and pH inactivation in comparison to free cellulase. Moreover, immobilized cellulase with and without cross-linking agent were investigated and the former had greater amount of immobilized cellulase and better operational stability. The amount of immobilized cellulase with the cross-linking agent was 92 mg/g support. Furthermore, the activity of the immobilized cellulase was still 85.5% of the initial activity after 10 continuous uses, demonstrating the potential of this immobilized cellulase for large-scale biofuel production.