Immobilization of lipase on silica nanoparticles by adsorption followed by glutaraldehyde cross-linking

In this study, Candida antarctica lipase B was immobilized on silica (SiO₂) nanoparticles by physical adsorption, and then cross-linked with glutaraldehyde (GA) to prepare cross-linked immobilized lipase (CLIL). During the condition of 1.28 mg/mL lipase concentration, 25 ℃ temperature, 2 h adsorption time, 0.01% GA (V/V) 7.5 mL and 2 h cross-linking time, the highest recovery activity of CLIL reached 87.82 ± 0.07% (22.55 ± 0.025 U/mg). Scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM) confirmed that lipase was immobilized on the surface of SiO₂ nanoparticles. The changes in secondary structures of CLIL indicated that cross-linking changed the secondary structure of lipase protein, which made the structure of CLIL more stable. Compared with the free lipase, the thermal stability and storage stability of CLIL was significantly improved, and the t_1/2 at 60 °C was extended. Studies had shown that it was a feasible method to obtain CLIL by cross-linking after adsorbing lipase on SiO₂ nanoparticles.