IMMOBILIZATION OF POLYSACCHARIDE DERIVATIVES ON POLYURETHANE SURFACE THROUGH LAYER-BY-LAYER SELF-ASSEMBLY AND PHOTOCHEMICAL MODIFICATION

Abstract

Polysaccharide derivatives were immobilized on the surface of polyurethane(PU) through layer-by-layer self-assembly technique and photochemical modification method.At first,azido-chitosan(AzCS) was synthesized and immobilized on the polyurethane substrates by UV irradiation.Then,lentinan sulfate(LS) and azido-chitosan were alternatively deposited on the polyurethane substrates through layer-by-layer self-assembly technique.Finally,the self-assembled multilayers were cross-linked by UV irradiation.From above steps,the polysaccharide derivatives modified polyurethanes were prepared.The surface properties of the modified polyurethanes were evaluated by infrared spectroscopy,UV-Vis spectroscopy,X-ray photoelectron spectroscopy and water contact angle measurement.The antibacterial activity against Escherichia coli and blood compatibility of unmodified and modified PU were tested in vitro,respectively.The results showed that the water contact angle of the modified surfaces decreased gradually during the successive buildup of the multilayers.The hemolysis test and platelet adhesion test both indicated that the blood compatibility of PU surfaces was improved after surface modification.Moreover,the modified surfaces showed antibacterial activity against Escherichia coli.The number of viable Escherichia coli on the modified surface decreased by 49%.Thus,the surface modification of polysaccharide derivatives through layer-by-layer self-assembly and photochemical modification not only improves the hydrophilicity and hemocompatibility of the modified PU,but also introduces special antibacterial bioactivity onto the modified surfaces.