Enhancing the catalytic properties of porcine pancreatic lipase by immobilization on SBA-15 modified by functionalized ionic liquid

The mesoporous silica SBA-15 was modified by carboxyl-functionalized ionic liquid (COOH-IL-SBA). The prepared support was used to immobilize porcine pancreatic lipase (PPL) by physical adsorption (PPL-COOH-IL-SBA) and covalent attachment (PPL-CON-IL-SBA). Enzymatic properties of the immobilized PPL were investigated in the triacetin hydrolysis reaction. It was found that carboxyl functionalized ionic liquid modification of the support surface was an effective method to improve the properties of immobilized PPL. Incorporating into the functionalized SBA-15 made PPL more resistant to temperature and pH changes, compared with PPL immobilized on parent SBA-15 (PPL-SBA). Especially, after the covalent attachment to a functionalized support, the stability of PPL was improved obviously, which retained 81.25% and 52.50% of the original activity after incubation for 20 days and four times recycling, respectively, whereas PPL-SBA exhibited only 58.80% and 27.78% of the original activity under the same conditions. In addition, physical and chemical properties of the supports and immobilized PPL were characterized by small-angle X-ray powder diffraction (SAXRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), nitrogen adsorption, nuclear magnetic resonance (NMR) and thermogravimetry (TG). The images and data confirmed chemical modification in SBA-15 and PPL immobilization on the tested support.

► Carboxyl ionic liquid modified SBA-15 is a good carrier for PPL immobilization.
► Structure and surface properties of the carriers affect the catalysis performance.
► After being covalently immobilized, the PPL exhibit the best stability.