Unravelling the potential of nitric acid as a surface modifier for improving the hemocompatibility of metallocene polyethylene for blood contacting devices

Design of blood compatible surfaces is obligatory to minimize platelet surface interactions and improve the thromboresistance of foreign surfaces when they are utilized as biomaterials particularly for blood contacting devices. Pure metallocene polyethylene (mPE) and nitric acid (HNO(3)) treated mPE antithrombogenicity and hydrophilicity were investigated. The contact angle of the mPE treated with HNO(3) decreased. Surface of mPE and HNO(3) treated mPE investigated with FTIR revealed no major changes in its functional groups. 3D Hirox digital microscopy, SEM and AFM images show increased porosity and surface roughness. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P < 0.05) for HNO(3) treated mPE. Hemolysis assay and platelet adhesion of the treated surface resulted in the lysis of red blood cells and platelet adherence, respectively indicating improved hemocompatibility of HNO(3) treated mPE. To determine that HNO(3) does not deteriorate elastic modulus of mPE, the elastic modulus of mPE and HNO(3) treated mPE was compared and the result shows no significant difference. Hence, the overall observation suggests that the novel HNO(3) treated mPE may hold great promises to be exploited for blood contacting devices like grafts, catheters, and etc.