Immobilization and catalytic activity of lipase on mesoporous silica prepared from biocompatible gelatin organic template

Mesoporous silica (MPS) with high surface area (518.8 m²/g), tunable pore size (3.6-13.7 nm) was synthesized using inexpensive sodium silicate as the source of silica and the biodegradable gelatin as the structure directing agent. The amorphous mesostructures of the materials were characterized by N₂ adsorption-desorption isotherms, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The synthesized MPS was then utilized as supports for immobilization of Porcine pancreatic lipase (PPL) by physical adsorption. The measurements of Fourier transform infrared spectroscopy (FT-IR), N₂ adsorption-desorption isotherms and energy-dispersive spectroscopy (EDS) demonstrated that PPL had been adsorbed into the channels of the MPS. The immobilized PPL was used for catalyzing hydrolysis reaction of triacetin, and its correlative catalytic activity was studied. Compared with free PPL, the immobilized PPL possessed superior adaptability in alkaline range (pH = 7.0-9.0), good thermal stability and excellent reusability in phosphate buffer solution in hydrolysis reactions of triacetin. The results also indicated that the immobilized PPL maintained 45% of its initial activity even after being reused six times.