Albumin immobilized polyurethane and its blood compatibility

Surface pretreatment with albumin on a blood contacting material inhibits platelet adhesion, activation, and subsequent thrombus formation. Although adsorbed albumin improves blood compatibility, rapid desorption occurs when this surface is exposed to circulating blood. In this study, human serum albumin was immobilized on a polyurethane (PU) surface to investigate its blood compatibility and extended effects on a blood-material interface. The PU surface was treated with hexamethylene diisocyanate (HMDI), and the PU-HMDI was further grafted with albumin to produce an albumin immobilized PU surface (PU-albumin). The PU-albumin surface was characterized by attenuated total reflection infrared electron spectroscopy for chemical analysis, scanning electron microscopy, and dynamic contact angle. Blood compatibility was evaluated by in vitro protein adsorption, platelet adhesion, and occlusion time in an ex vivo rabbit arterio-arterial shunt. Immobilization of albumin was confirmed by the disappearance of the -NCO peak observed at 2,250 cm-1 on the PU-HMDI surface by infrared spectroscopy and the existence of sulfur atomic percent by electron spectroscopy for chemical analysis. The concentration of PU-albumin was approximately 5.8 micrograms/cm2. The PU-albumin also showed a slight increase in hydrophilicity on the Wilhelmy plate method, and there was less fibrinogen adsorption than a PU control. In addition, PU-albumin had less platelet adhesion, platelet activation, and thrombogenicity. The ex vivo occlusion time of untreated PU was 50 min, that of PU-albumin was extended to 150 min, indicating that a PU-albumin surface has better blood compatibility than PU alone.