Alkali-Induced ZIF-8 for Enhanced Lipase Immobilization and Enantioselective Resolution of (R,S)-1-Phenylethanol

Zeolitic imidazolate framework-8 (ZIF-8) is an important support for enzyme immobilization due to its good biocompatibility and structural tunability. However, the inherent structural characteristics of conventional ZIF-8 suffer from limited specific surface area, thereby restricting the achievable enzyme loading. In this study, we developed a novel alkali-induced (IA) strategy using sodium hydroxide to prepare IA-ZIF-8 with markedly enhanced textural properties. Subsequently, Pseudomonas fluorescens lipase (PFL) was successfully immobilized onto IA-ZIF-8 via physical adsorption, and the optimal conditions were systematically investigated. Compared with conventional ZIF-8, IA-ZIF-8 achieved a larger specific surface area (1462.3 m2/g), and a 9.8% increase in PFL loading. The resulting biocatalyst, IA-ZIF-8-PFL, exhibited significantly enhanced thermal and pH stability due to the confinement effect and protective microenvironment from the carrier. When the biocatalyst was applied to the chiral resolution of (R,S)-1-phenylethanol, it showed satisfactory catalytic activity and enantioselectivity with a conversion of 24.4% and an ees of 25.7%. In addition, IA-ZIF-8-PFL retained satisfactory reusability over five successive cycles. This work demonstrates that IA-ZIF-8 is a highly efficient carrier for immobilizing lipase and offers a green biocatalyst for the efficient preparation of chiral drug intermediates.