Preparation of magnetic silica nanoparticles and their application in laccase immobilization

Laccase was immobilized on the silanized magnetic silica nanoparticles by using glutaraldehyde as the cross-linker. Immobilization of laccase was investigated and its immobilizing conditions were optimized. The results were achieved with the concentration of 8% glutaraldehyde, immobilizing time of 6 h, the buffer of pH 7.0 and initial laccase concentration of 0.15 g/L. The optimum pH and temperature of immobilized laccase were 4.0 and 20°C, respectively. After the immobilized enzyme was kept at 60°C for 4 h, it remained 60.9% of its initial activity. The immobilized laccase could retain above 55% of activity after 10 consecutive operations. The experimental results showed that the thermal stability and operational stability of immobilized laccase were improved in comparison with free laccase.