Functionalization of PTFE Surface after Plasma Immersion Ion Implantation Treatment for Cardiovascular Application

Small diameter vascular grafts made of expanded polytetrafluoroethylene (ePTFE) suffer from the poor patency rate because of the thrombosis and intimal hyperplasia [1,2], which are result from the lack of endothelialization and chronic inflammation [3,4]. Therefore, grafts with reduced thrombogenicity, rapid endothelialization as well as the immunomodulating ability are highly desirable. In this work, plasma immersion ion implantation (PIII) technique was used to modify the surface of PTFE to meet these needs. After nitrogen (N₂) PIII treatment, PTFE surface becomes cytocompatible that is sufficient for endothelialization. More importantly, a free radical reservoir is generated underneath the surface. These free radicals continuously migrate to the surface and react with the environment. Taking advantage of this special mechanism, various functional biomolecules can be covalently immobilized on the surface of PTFE by simply incubating the modified samples in corresponding solutions. Heparin, SDF-1α, as well as the CD47 are shown to be successfully bound to the surface with their bioactivities well reserved. The resultant surface possesses the multifunctional properties of reduced thrombogenicity, endothelial progenitor cells (EPC) recruitment potential, and the anti-inflammatory ability. Therefore, this functionalized surface is promising in facilitating the rapid in-situ endothelialization and favorable host immune response that finally contribute to the superior long-term patency [5].