Abstract
Polyurethane have been used as biomaterials due to their excellent physical and mechanical properties. Although they have superior biocompatibility to other polymers', they are still belonged to foreign matters for human bodies. When they are implanted to the body, rejection and immunoresponse are induced. Their biocompatibility must be improved for more wide-ranging applications. Biocompatibility, hemocompatibility in particular, is the most important property blood-contacting materials should have. In this investigation, the pMPC was incorporated onto polyurethane membranes via plasma induced graft copolymerization. DPPH assay experiment indicated the maximum amount of peroxide group produced onto polyurethane membrane reached 1.39×10-7mol/cm2 （experimental condition : plasma power of 60 watts, the plasma irradiating time of 60 seconds, and vacuum gauge of 200 mini torrs）. The grafted amount of pMPC onto polyurethane membrane was measured by 31P-NMR spectra. It was observed that the grafted amount of pMPC was influenced by the MPC concentration and the time for graft copolymerization. The maximum grafted amount of pMPC could reach 388μg/cm2（experimental condition : polymerization time of 24 hours, MPC solution concentration of 0.2M, reaction temperature of 80℃）. ESCA experiments pointed out the surface phosphorous atomic concentration increased with the increasing of the grafted amount of pMPC, The biocompatibility of the MPC-modified PU was examined by cellular adhesion, protein adsorption, platelet adhesion, and the Whole blood adhesion assays. When the grafted amount of pMPC reached 388μg/cm2, the number of cells adhered was only 2.1 percentage of that of cells adhered onto the origin PU. Protein adsorption experiments showed the adsorbed amount of protein decreased with the increasing grafted amount of pMPC. The SEM photographs of platelet adhesion showed the platelet adhered amount decreased with the increasing grafted amount of pMPC .Finally, the Whole blood adhesion assays indicated the chitosan surface produced fibrins, and accompanied by the entwining of blood cells. The above-mentioned results revealed the grafting of pMPC indeed improved the hemocompatibility of PU membranes .