Blood compatibility assessment of metallocene polyethylene following nitric acid treatment

Abstract

Metallocene polyethylene (mPE) has been known for its excellent physical and mechanical properties, but its poor hemocompatibility limits its clinical application. Objective of this study was to analyze the physicochemical properties and blood compatibility of mPE following nitric acid (HNO3) treatment. Characterization tests were performed using 3D Hirox, SEM, AFM, contact angle and FTIR. Blood compatibility of the sample was studied by conducting blood coagulation assays; hemolysis assay, PT, APTT, platelet adhesion and protein adsorption test. Result shows that the contact angle of the mPE treated with HNO3 decreased from 86º to 69.7º. Surface of the mPE and the HNO3 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. The protein adsorption studies show that the adsorbed albumin increased and adsorbed fibrinogen decreased in 60 minutes HNO3 treated sample. Blood coagulation assays prothrombin time (PT) and activated partial thromboplastin time (APTT) were delayed significantly (P < 0.05) for the 60 minutes HNO3 treated sample. Hemolysis assay and platelet adhesion of the treated surface resulted in reduced lysis of red blood cells and platelet adherence indicating improved hemocompatibility of HNO3 treated mPE. To determine that HNO3 does not deteriorate elastic modulus of mPE, the elastic modulus, tensile strength and tensile strength at break of mPE and HNO3 treated mPE was compared and the result shows that HNO3 treatment does not deteriorate the mechanical properties of mPE. To conclude, the overall observation suggests that the novel HNO3 treated mPE may hold great potential to be exploited for various temporary blood contacting devices like catheters, endoscopy tip and etc.