High Density Glycosylation Of Microporous Polypropylene Membranes And Their Potential Applications

The glycocalyx on the external cell membranes endows the cell membrane surfacewith well hydrophilicity and biocompatibility, which not only prevents undesirablenon-specific adhesion of foreign substance, but also possesses specific recognitionproperties for target molecules. It widely participates in biological processes, such ascellular differentiation, development, immune response, senescence, carcinogenesis. Thedense structure of carbohydrate layer in glycocalyx enhances the affinity betweencarbohydrates and their target molecules, which meets the demand of differentphysiological activities. To construct glycosylated layer on the surface of polymericmembrane is expected to biomimic the glycocalyx and expand the application fields ofmembranes.In this thesis, a versatile method was constructed to prepare high-density glycosylatedmicroporous polypropylene membranes (MPPMs) with glycobiological functions to mimicthe the glycocalyx of cell membranes. Our detailed works are mainly concentrated on thefollowing aspects:1. Using FeCl₃ and BP as photoinitiators, 2-hydroxyethyl methacrylate (HEMA) wassuccessfully grafted on MPPMs by UV-induced grafting polymerization. The synergisticeffect between FeCl₃ and BP greatly enhanced the grafting density (GD). Thepoly(HEMA)-grafted MPPMs showed well protein resistance and potentialhemocompatibility due to the enhancement of hydrophilicity.2. Using poly(HEMA)-grafted MPPMs as supports, high density glycosylation ofmembranes was achieved by a versatile method with mono- and di-saccharides. The highGD of HEMA and high catalytic activity of BF₃·Et₂O greatly increased the binding degree(BD) of saccharide moieties. The poly(HEMA) chains hanging with a great number ofsaccharide moieties mimic the structure of glycan on the cell membrane, which showstrong "glycoside cluster effect" and endow the glycosylated MPPMs with goodglycobiological functions.3. The glucosylated MPPMs were used as affinity membranes for Con A separation onthe basis of the specific interactions between saccharide ligands and lectins. The bindingcapacity of glucosylated MPPMs increased by multilayer adsorption of Con A andincreased with BD of glucose. Compared with the competitive eluants, such as glucose andmethylα-mannopyranoside, 1 M Hac solution is more effective to elute the adsorbed Con A from the affinity membranes.4. The glycosylated MPPMs were taken as the substrates to culture hepatocytes invitro. The number of hepatocytes adhered on the poly(HEMA)-grafted and glucosylatedMPPMs was less, while that on the galactosylated and lactosylated MPPMs werecomparable with the collagen coating membranes. Hepatocytes became spreading on thecollagen coating MPPM, and had strong interaction with substrate. However, hepatocyteson the galactosylated and lactosylated MPPMs maintained spherical shapes and formedspheroid with multiple cells, showing weak interaction with substrate and stronginteraction between cell-cell.