Surface Modification Of Polycarbonateurethane Film To Improve Its Hemocompatibility By Covalent Linkage Of Heparin

In order to improve blood compatibility of polycarbonate urethane, three different methods attaching heparin to the surface of polycarbonate urethane (PCU) were investigated and the modified polymers were characterized by variety methods. Multi-step covalent method was used to attach heparin to PCU surface, to determining the amount of heparin immobilized on PCU surface by toluidine blue colorimetric method, but the heparin grafting density was little.NH3 plasma method was used to attach heparin to the PCU surface. The PEG grafted PCU film with ammonia plasma treatment, to introduce the amino groups onto the PCU film surface, then grafting heparin. To determining the amount of heparin immobilized on PCU surface by toluidine blue colorimetric method, and the heparin grafting density was increased.Amino-PEG method was also used to attach heparin to the PCU surface by a three-step procedure. First, the PCU film was treated with hexamethylene diisocyanate (HDI) in toluene. Second, the Amino-PEG (Mn = 2000) was reacted with isocyanate groups linking on the surface of PCU film to obtain the PCU-APEG film. Third, the PCU-APEG was coupled with heparin. The optimal heparin graft conditions were determined by examining lots of reaction process conditions. The amount of heparin covalently immobilized on the PCU-APEG membrane was determined by toluidine blue method. The modified surfaces were characterized by IR, XPS, DSC, water contact angle measurements and water uptake measurements.The surface morphologies of the modified and unmodified PCU films were characterized by SEM and AFM. All the results showed that heparin and APEG were grafted on PCU film successfully. The phenomenon of the Platelet adhesion experiment showed that the blood-compatibility of the heparin grafted PCU film surface were improved significantly.