α-Glucosidase immobilization on the metal–organic framework composite membrane for enzyme inhibitor screening

Abstract

In this study, a novel screening approach is presented, merging capillary electrophoresis analysis with an enzymatic assay employing immobilized α-glucosidase. A metal–organic framework composite membrane was devised for α-glucosidase immobilization. Employing polyvinylidene fluoride (PVDF) as the substrate material, it was functionalized with dopamine, creating a polydopamine composite layer. This layer acted as a covalent linker, anchoring Zn²⁺, which subsequently chelated with the organic ligand 2-ethylimidazole, leading to the self-assembly of a three-dimensional porous framework ZIF-8. This structure facilitated the in situ encapsulation of α-glucosidase. Characterization techniques including scanning electron microscopy, Fourier transform infrared-attenuated total reflectance spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction validated the composite material's structure. A thorough investigation of various parameters affecting immobilization was conducted. The immobilized α-glucosidase exhibited enhanced pH tolerance, thermal stability, and remarkable reusability, retaining 79.3% of its original activity over 10 cycles, with a batch-to-batch reproducibility of 5.9% (n = 5). Its Michaelis–Menten constant (K_m) was determined to be 2.85 mM. Application of this immobilized enzyme in screening potential inhibitors from 13 traditional Chinese medicines revealed Sanguisorba radix as the most potent inhibitor. This study underscores the potential of this immobilized enzyme screening strategy for identifying enzyme inhibitors in traditional Chinese medicines.