Preparation and blood compatibility of polyurethane films blending and grafting with heparin in the same solvent system

Heparin was homogeneously mixed with polyurethane in the co-solvent of tetrahydrofuran and water through adjusting the ratio of the two solvents. After the film was prepared with casting method, heparin was homogeneously blended in polyurethane films. At the same time, through reaction of heparin with l-(3-dimethyl aminoprophyl)-3-ethylcarbodimide hydrochloride (DCC1), heparin was partly grafted with the residual of polyurethane and the films containing free and covalent heparin were obtained using solvent casting. The heparin release rate was investigated with toluidine blue heparin assay (TBHA). The blood compatibility of polyurethane films was assessed with thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (APTT). The results indicated that polyurethane containing heparin showed expected blood compatibility and polyurethane containing free and covalent heparin had the excellent bioactivity of free heparin and the long-term blood compatibility of covalent heparin.