To prepare the biomaterial surface having both lubricity and biocompatibility, we aimed to prove the mechanism of the resistance of friction and protein adsorption with grafting polymer. We prepared poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) grafted layer using an atom transfer radical polymerization (ATRP) method, which had the advantage of controlling surface structures on nanoscale. From the results of surface characterization, it was confirmed that the thickness of the PMPC

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... d layer was 4-10 nm and the conformation of the PMPC grafted layer was brushlike. We investigated the friction properties in air and in water with an atomic force microscopy (AFM). The friction coefficients of the PMPC brush layers were decreased dramatically in water and the resistance of friction depended on the thickness of the PMPC brush layer. We also investigated the protein adhesion properties by measuring the force-distance curves using the AFM cantilever immobilized with a bovine serum albumin (BSA). The adhesion force between the BSA and the PMPC brush layers were markedly reduced and the resistance of the BSA adhesion depended on the thickness of the PMPC brush layer. For resisting both friction and protein adsorption in water, it was a key factor to keep the thick hydrated layer made by the elongated hydrophilic PMPC brush chains.