Immobilization of Lipase by Ionic Liquid-Modified Mesoporous SiO₂ Adsorption and Calcium Alginate-Embedding Method

Porcine pancreatic lipase (PPL) was immobilized onto functionalized ionic liquid-modified silica carrier using gelatinization and physical adsorption. The immobilized lipase was characterized with N₂ adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) before and after modification and immobilization. The results showed that the modification of the ionic liquid and the introduction of lipase had been successfully approved. The rate of enzymatic reaction and its influencing factors was primarily studied by enzymatic reaction kinetics. K _m values of PPL-SiO₂@CA and PPL-IM/BF₄-SiO₂@CA were 4.9 and 3.7 mg/ml, respectively. It indicated that the modification of the functionalized ionic liquid enhanced the affinity between the immobilized enzyme and the substrate. The immobilization efficiency, specific activity, optimum temperature, optimum pH, thermal stability, reusability, and storage stability of the immobilized enzyme were investigated. We found that the stability of the immobilized enzyme was significantly higher than that of the unmodified immobilized enzyme. Specially, PPL-IM/BF₄-SiO₂@CA maintained good thermal stability and retained more than 92% of its activity at 65 °C after preheating 3 h. Graphical Abstract Above, the immobilized lipase maintained more than 92% of its initial activity after incubating at 65 °C for 3 h.