It is well known that the thrombo-resistance of polymeric biomaterials can be improved by surface endpoint immobilization of heparin. Current heparinization methods are complex and costly, and may degrade the mechanical properties of the base polymer. The proposed study will determine the feasibility of synthesizing tough, thermoplastic polyurethane biomaterials with 'built-in' binding sites for heparin. Heparinization will be achieved by simply soaking the device/component made from the subject polymer, in an aqueous heparin solution. A diamine-diamide-diol (PIME), which has an established ability to bind heparin, will replace some of the normal diol 'chain extender' in a well-established biomedical polycarbonate-urethane. Surfaces of the resulting PIME-containing polyurethanes will be characterized by Sum Frequency Generation Spectroscopy (SFG), Contact Angle Goniometry, and Atomic Force Microscopy. Heparin activity will be determined by Activated Partial Thromboplastic Time (APTT) on freshly synthesized and sterilized device analogues. Preliminary results indicate surface PIME can be easily distinguished from the base polyurethane by SFG. Also, non-sterile heparinized PIME-containing polyurethanes exhibit an APTT of >500 seconds compared to <55 seconds for polyurethanes without PIME. Biomaterials with inherent affinity for heparin will reduce the cost of surface heparinization and are therefore applicable to a wide range of blood-contact medical devices and prostheses.
