Photo-immobilization of a phospholipid polymer for surface modification.

A photo-reactive polymer having a phospholipid polar group was prepared, and the polymer was photo-immobilized on polymeric surfaces, where its interactions with biocomponents were investigated. By using a photo-immobilization method, the polymer was used for surface modification of polyethylene and polypropylene, polymers whose surfaces were not treated in our previous development of the phosphorylcholine-derived polymer. The photo-reactive polymer was synthesized by a coupling reaction involving copolymer consisting of 2-methacryloyloxyethyl phosphorylcholine and methacrylic acid with 4-azidoaniline. When the polymer was unpattern immobilized on the surface, X-ray photo-electron spectroscopic analysis and static contact angle measurements were performed. It was shown that the surface was covered with phospholipid polar groups. Micropattern immobilization was carried out using a micropatterned photo-mask. Measurements using atomic force microscopy showed that the swelled micropatterned polymer was five times as thick as the dried one. Protein adsorption and platelet adhesion were reduced on the polymer-immobilized regions. Mammalian cells did not adhere, and formed aggregates on the immobilized regions. In conclusion, the photo-reactive phospholipid polymer was covalently immobilized on the conventional polymer surfaces and it tended to reduce interactions with proteins and cells.