Abstract:Hierarchical porous zeolitic imidazolate framework-8 (ZIF-8) materials have larger pore sizes compared with conventional ZIF-8 materials, and show better application prospects in the field of immobilized enzymes. At present, the effect of immobilizing Rhizopus oryzae lipase (ROL) using hierarchical porous ZIF-8 material remains unclear. In this study, an amorphous zeolitic imidazolate framework-8 (aZIF-8) material was prepared by adjusting the initial molar ratio of the precursor of ZIF-8 material, and the immobilized lipase ROL@ZIF-8 and ROL@aZIF-8 were prepared by in situ self-encapsulation based on the ZIF-8 and aZIF-8 materials, respectively. The morphological and structural differences of ZIF-8, aZIF-8, ROL@ZIF-8 and ROL@aZIF-8 were investigated by using infrared spectroscopy, X-ray diffractometer and scanning electron microscope, etc. The enzyme activities of ROL@aZIF-8 prepared under different ROL mass concentrations were compared with those of the same mass concentration of ROL. The acid-alkali stability, temperature tolerance, storage stability, and hydrolysis ability of ROL and ROL@aZIF-8 against dibutyl phthalate (DBP) and diisobutyl phthalate (DIBP) were investigated. The results showed that the aZIF-8 material presented an amorphous morphology containing various forms such as cruciate flower-like, square, and spherical, and was a hierarchical porous material with micropores and mesopores. ROL@aZIF-8 prepared at ROL mass concentration of 4mg/mL showed the maximum enzyme activity of 5.69U/mg. The hydrophobicity and hierarchical porous properties of the aZIF-8 material contributed to the higher enzyme activity of ROL@aZIF-8 than that of ROL at the same mass concentration of ROL. ROL@aZIF-8 showed better alkali stability, temperature tolerance, storage stability, and higher hydrolytic capacity for DBP and DIBP than ROL.