Evaluation of biocompatibility of the surface of polyethylene films modified with various water soluble polymers using Ar plasma-post polymerization technique

Surface modified polyethylene (g-PE), PMPC-g-PE, PGEMA-g-PE, PNIPAAm-g-PE and PHPMA-g-PE films with the water soluble polymers such as poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC), poly[2-(glucosyloxy)ethyl methacrylate] (PGEMA), poly(N-isopropylacrylamide) (PNIPAAm) and poly[N-(2-hydroxypropyl) methacrylamide] (PHPMA) were prepared by graft copolymerization using an Ar plasma-post polymerization technique. The surface of the g-PE films was characterized by means of X-ray photoelectron spectroscopy and the grafting percentage of PMPC, PNIPAAm and PHPMA was found to be 5.31, 2.83, and 3.40% for the corresponding g-PE film. Biocompatibility of the g-PE films was evaluated by the adsorption of serum proteins and the Michaelis constant (Km) for the enzymatic reaction of thrombin with synthetic substrate S-2238 in the presence of g-PE film. The biocompatibility of water soluble polymers such as PMPC, polyoxyethylene (POE), PGEMA, PNIPAAm and PHPMA was also evaluated by the same enzymatic reaction of thrombin with S-2238 in their polymer solutions. The Km values in the presence of water soluble polymers was found to decrease in the order PMPC > POE > PGEMA > PNIPAAm > PHPMA. As a conclusion, PMPC-g-PE film exhibited the most biocompatibility among g-PE films because its surface adsorbed less protein than those of the untreated PE and other g-PE films and it showed the largest Km for the enzymatic reaction.