Blood compatibility of polyurethane surface grafted copolymerization with sulfobetaine monomer

Surface modification is an effective way to improve the hemocompatibility and remain bulk properties of biomaterials. Recently, polymer tailed with zwitterions was found having good blood compatibility. In this study, the grafting copolymerization of sulfobetaine onto polyurethane surface was obtained through two steps. In the first step, polyurethane film coupled with vinyl groups was obtained through the reaction between the carboxyl group of acrylic acid (AA) and the NH-urethane group of polyurethane by dicyclohexylcarbodiimide (DCC). In the second step, sulfobetaine was grafted copolymerization on the surface using AIBN as an initiator. The reaction process was monitored with ATR-IR spectra and X-ray photoelectron spectroscopy (XPS) spectra. The wettability of films was investigated by water contact angle measurement. The blood compatibility of the grafted films was evaluated by platelet adhesion in platelet rich plasma (PRP) and protein absorption in bovine fibrinogen (BFG). Low platelet adhesion was observed on the grafted films incubated in PRP for 1 and 3 h, respectively. The protein absorption was reduced on the grafted films after incubated in bovine fibrinogen for 2 h. All of these results revealed that the improved blood compatibility was obtained by grafting copolymerization with zwitterionic monomer of sulfobetaine onto polyurethane film. In addition, introducing vinyl groups onto surface through DCC and AA is a novel method to functionalize polyurethane for further modification.