Multilayer adsorption of lectins on glycosylated microporous polypropylene membranes

Affinity membranes are fast growing for bioseparation techniques. Using membrane as the chromatography media can overcome some disadvantages of the column chromatography. The products of affinity membrane chromatography possess extremely high purity due to the highly specific binding between the ligands immobilized on the membranes and the targets in the solution. The glycosylated microporous polypropylene membranes (MPPMs) can be used as affinity membranes for proteins separation on the basis of the specific interactions between saccharide ligands and lectins. These glycosylated membranes can be facilely prepared by the immobilization of saccharide ligands on the poly(2-hydroxyethyl methacrylate) (poly(HEMA))-grafted MPPMs through the reaction between hydroxyl groups and acetylated saccharides. The tentacle-like poly(HEMA) chains on the membrane with pendent saccharide ligands not only increase the specific area of membrane but also are benefit to adsorb multilayer proteins, which can enhance the binding capacity of protein on the affinity membrane. The glucose modified MPPMs can specifically adsorb one kind of lectin, Concanavalin A (Con A). Binding degree of glucose residues on the affinity membrane plays a positive role on the binding capacity of Con A. The protein molecules adsorbed on the outer layer of flexible polymer chains can be transferred into the inner layer through the reversible binding between Con A and glucose residues. Therefore, multilayer of Con A is adsorbed on the affinity membrane. Compared with the competitive eluants, such as glucose and methyl α-mannopyranoside, 1 M HAc solution is more effective to elute the adsorbed Con A from the glucose modified MPPMs. Besides, the results of CLSM directly demonstrate the specific adsorption of proteins on the glycosylated MPPMs.