title: Alteration of PTFE surface to increase its blood compatibility.
abstract: The aim of this study is to increase the blood compatibility of polytetrafluoroethylene (PTFE), one of the preferred materials for soft-tissue application, by a two-step procedure: first, the surface was activated by hydrogen plasma followed by acrylamide attachment and, secondly, hirudin, a potent antithrombogenic protein from leeches, was immobilized to the surface. Plasma treatment conditions were optimized and different surfaces were characterized by water contact angle measurements, ATR-FT-IR and X-ray photoelectron spectroscopy (XPS). It was seen that the contact angle of the PTFE decreased from 126° to 55° in optimum conditions. Acrylamide (25% (w/v) in ethanol/acetone (50%, v/v)) was grafted to the surface by the help of argon plasma treatment (1 min, 50 W, 13 Pa). The water contact angle was further decreased to 33° with acrylamide grafting and amide groups, which were subsequently used in protein immobilization, and could be detected both by ATR-FT-IR and XPS analysis. In the second part, hirudin was attached to these amide groups on PTFE surface by an optimized EDC/NHS activation procedure. Then a thrombogenicity test was done to detect hirudin activity. The results showed that there is a significant decrease in the clot formation compared with the untreated PTFE samples and ca. 0.3-0.4 ATU/cm(2) (22-29 ng/cm(2)) of hirudin was enough to prevent the clot formation. A preliminary study showed that the hirudin immobilized membranes keep their antithrombogenic activity for at least 40 days in 37°C in PBS (0.1 M, pH 7.4). As a result, the blood compatibility of PTFE surfaces was ameliorated by plasma-induced monomer grafting and hirudin immobilization, and an alternative material was obtained to be used in medical applications such as vascular grafts, catheters, etc.
authors.affiliation: Istanbul Technical University, Molecular Biology-Genetics and Biotechnology Program (MOBGAM), 34469 Maslak, Istanbul, Turkey.
authors.forename: Sakip
authors.initials: S
authors.lastname: Onder
authors.forename: Kursat
authors.initials: K
authors.lastname: Kazmanli
authors.forename: Fatma Nese
authors.initials: FN
authors.lastname: Kok
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D001769:Blood; D002021:Buffers; D006629:Hirudins / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D055767:Immobilized Proteins / Q000737:chemistry; D058626:Plasma Gases / Q000737:chemistry; D011138:Polytetrafluoroethylene / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002021:Buffers; D006629:Hirudins; D055767:Immobilized Proteins; D058626:Plasma Gases; D014867:Water; D006859:Hydrogen; D011138:Polytetrafluoroethylene