Reduction in the Antithrombogenicity of Polytetrafluoroethylene and Polyethylene Caused by Radiation-Induced Oxidation

Abstract

To examine the influence of radiation-induced oxidation on the antithrombogenicity of polymers, polytetrafluoroethylene (PTFE) and low density polyethylene (PE) tubes were irradiated with gamma-ray and then treated with water at 50°C, and surface characterization and evaluation of their antithrombogenicity were done. Irradiation was carried out mainly in argon with 0.14-0.47 MR for PTFE and in air or water with 0.44-8 MR for PE. Data of ESCA and zeta-potential showed the introduction of oxygen-containing groups onto the irradiated surfaces (ca. 10 mol% for the irradiated PE), and the contact angle of water for the PTFE and PE surfaces decreased to 98°and 80°, respectively. The relative patent time in canine peripheral veins reduced markedly with dose. No activation of complement and contact phase were, however, observed for all specimens in vitro, while platelet adhesion was found to increase for the irradiated specimens in vivo. Consequently, the reduction in the antithrombogenicity of the irradiated surfaces is mainly due to the enhancement of platelet activation resulting from a decrease in hydrophobicity of the surfaces.