Fabrication of glycosylated surfaces on microporous polypropylene membranes for protein recognition and adsorption

Abstract

Synthetic membranes with glycosylated surfaces have great potential in pharmaceutics, clinically in diagnosis and protein purification. A versatile method of constructing glycosylated membrane surfaces was developed using poly(2-hydroxyethyl methacrylate) (poly(HEMA))-tethered microporous polypropylene membranes (MPPMs) as supports. Glucose moieties were bound on the membrane surfaces through the reaction between glucose pentaacetate and the hydroxyl group of poly(HEMA). The binding degree of glucose moieties on the MPPMs was controlled in a wide range by changing the grafting degree of poly(HEMA). The maximum binding degree reaches 10 µmol cm⁻² when the grafting degree of poly(HEMA) on the membrane surface is 29.40 µmol cm⁻². These glycosylated membrane surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. Water contact angles of the glycosylated membrane surfaces before and after removing the acetyl groups differ remarkably from each other. After deprotection, the glycosylated membrane surfaces become highly hydrophilic, which greatly inhibits the non-specific adsorption of bovine serum albumin or peanut agglutinin on these surfaces. Furthermore, the glycosylated membranes can selectively recognize concanavalin A (ConA). When the binding degree of glucose moieties is above 0.39 µmol cm⁻², the “glycoside cluster effect” occurs and plays an important role in the recognition and adsorption of proteins. Due to the reversible affinity, the adsorbed ConA can be desorbed with glucose solution. The results suggest that these MPPMs with glycosylated surfaces are promising for the isolation/purification of proteins.