Fabrication of an organic-inorganic nanocomposite carrier for enzyme immobilization based on metal-organic coordination

An organic-inorganic nanocomposite which combined mesoporous silica SBA-15 and chitosan using a carboxyl functionalized ionic liquid as the bridging agent (SBA@CS) was successfully fabricated, and was used to immobilize porcine pancreas lipase (PPL) by physical adsorption, cross-linking and metal-organic coordination, respectively. The as-prepared carriers were characterized by scanning electron microscopy, Fourier transform infrared and energy-dispersive X-ray spectroscopy. Compared with immobilization onto the pure mesoporous silicon material SBA-15, all the batches of PPL immobilized onto organic-inorganic nanocomposites showed higher activity, improved stability and reusability as well as better resistance to pH and temperature changes. Among the immobilized PPLs, immobilization based on Co2+ coordination (SBA@CS-Co-PPL) produced the best enzymatic properties. The maximum immobilization efficiency and specific activity of 79.6% and 1975.8 U g(-1) were obtained with SBA@CS-Co, separately. More importantly, the activity of immobilized enzyme can still maintain 84.0% after 10 times of reuse. These results demonstrated that thus prepared organic-inorganic nanocomposite could be an ideal carrier for enzyme immobilization by metal-organic coordination.