Tannic acid-aminopropyltriethoxysilane co-deposition modified polymer membrane for α-glucosidase immobilization

Mussel-inspired catechol-amine co-deposition is an effective modification strategy for various materials. In this work, polyvinylidene fluoride (PVDF) membrane was employed as the carrier for alpha-glucosidase immobilization. By virtue of the co-polymerization of tannic acid (TA) and 3-aminopropyltriethoxysilane (APTES) and the hydrolysis of APTES, a hierarchical layer-colloidal nanospheres coating was decorated on the surface of PVDF membrane. Subsequently, alpha-glucosidase was covalently bound to the modified PVDF membrane through Schiff base reaction and Michael addition reaction between the residual quinine groups in the coating and the amino groups in enzyme molecules. Several parameters affecting the im-mobilization procedure were investigated thoroughly. The morphology and functional groups of the pre-pared composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared -Attenuated total reflectance spectroscopy (FTIR-ATR), and X-ray photoelectron spectroscopy (XPS). Com-bined with capillary electrophoresis (CE) analysis, the performance, enzyme reaction kinetics and inhi-bition kinetics of PVDF-immobilized alpha-glucosidase were studied. The immobilized enzyme exhibited the enhanced tolerance to temperature and pH value. In addition, it possessed good reusability maintain-ing 77.1% of initial relative activity after 11 recycles, and batch-to-batch reproducibility with RSD of 4.3% ( n = 10). The Michaelis-Menten constant (Km) of immobilized enzyme was calculated to be 4.16 mM, and IC50 value of acarbose was 0.10 mu M. Finally, the PVDF-immobilized alpha-glucosidase was applied to screening potential inhibitors from 13 kinds of traditional Chinese medicines (TCMs), among which San-guisorba Radix exhibited the strongest inhibitory activity. The positive results suggested that TA/APTES co-deposition was a simple and mild functionalization method for chemically inert polymer membrane and the proposed screening method was a reliable approach for discovering enzyme inhibitors from TCMs.(c) 2022 Elsevier B.V. All rights reserved.