Biocompatibility of Chitosan/Heparin Multilayer Coating on NiTi Alloy

Nickel Titanium alloy has been used widely in clinical iatrology for years because of its unique shape memory capability, proper elasticity and considerable biocompatibility. But as an implanted material, its possible release of Ni ions which might cause toxic effect and its improvable biocompatibility draw attentions of researchers. In this study, chitosan/heparin multilayer is coated on NiTi shape memory alloy by electrostatic self-assemble method. Field emission scanning electron microscopy (FE-SEM), contact angle test is used to show its surface character; hemolysis test, dynamic clotting time experiment and platelet binding test are utilized to investigate the blood compatibility of the materials. The results reveal that the hydrophilic character of the coated one is better than the substrate, and blood compatibility of NiTi is improved by coating treatment.