Optimized Molecular Structure of Photoreactive Biocompatible Block Copolymers for Surface Modification of Metal Substrates

Poly(2-methacryloyloxyethyl phosphorylcholine)-b-poly(2-methacryloyloxyethyl phosphate-co-2-cinnamoyloxyethyl methacrylate) (PMPC-b-P(MPA/CMA)) was prepared by reversible addition-fragmentation chain transfer (RAFT)-controlled radical polymerization. The block copolymers were coated on stainless steel (SUS316L) and other metal substrates, and then the surface was subsequently irradiated with UV light. The wettability of a specimen surface treated with a block copolymer was improved in comparison with that of an untreated SUS316L plate. From X-ray photoelectron spectroscopy (XPS) data, it was clear that the P(MPA/CMA) block worked as a binding site on the SUS316L surface. The surface density of the block copolymer-immobilized SUS316L surface was influenced by the molecular weight of the PMPC block. The stability of the immobilized layer was improved by UV irradiation, which induced intermolecular dimerization of the CMA. In addition to the SUS316L surface, various other metal surfaces could be modified by surface immobilization of block copolymers. Serum protein adsorption and fibroblast adhesion were effectively reduced by surface immobilization of block copolymers with optimal molecular weight of PMPC block. The nonfouling property was preserved after 1 week of cell cultivation.