Stable surface coating of silicone elastomer with phosphorylcholine and organosilane copolymer with cross-linking for repelling proteins.

Poly(dimethylsiloxane) (PDMS)-based polymers are widely used in blood-contacting medical devices. However, the hydrophobic property causes adsorption of plasma proteins and activates blood clotting. There are several techniques for PDMS surface modification. However, the efficacy is limited to short duration due to the low glass transition temperature of PDMS. The goal of this study is to fabricate a highly stable polymer membrane with blood-compatibility on PDMS. Here, we synthesized random copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC), 3-methacryloxypropyl trimethoxysilane (MPTMSi) and 3-(methacryloyloxy) propyl-tris(trimethylsilyloxy) silane (MPTSSi). These copolymers are covalently and physically immobilized on PDMS surface by silane coupling (cross-linking) and hydrophobic interaction. Protein adsorption was significantly reduced on MPC copolymer-coated PDMS surface. In particular, copolymer containing 50% MPC unit was the most effective and maintained the effect for the longest duration (84 days). From analyses of X-ray reflectometry (XRR) and X-ray photoelectron spectroscopy (XPS), it is determined that the density of the polymer membrane is an important factor for the long-term stability. In addition, the coating of PDMS with MPC copolymer does not influence on oxygen permeability.