Platelet adhesion and procoagulant activity induced by contact with radiofrequency glow discharge polymers: Roles of adsorbed fibrinogen and vWF

The potential hemocompatibility of radiofrequency glow discharge (RFGD) pol ymers made by copolymerization of mixtures of hexafluoropropene and ethylen e (C3F6/C2H4) or acrylic acid and 1,7-octadiene was investigated using in v itro assays for platelet adhesion and platelet catalyzed thrombin generatio n. Thrombin generation rate normalized to platelet number was used as a mea surement of platelet activation (procoagulant activity). RFGD polymers prod uced by copolymerization of acrylic acid and 1,7-octadiene contained varyin g amounts of carboxylic acid species as determined by electron spectroscopy for chemical analysis (ESCA). These polymers induced little variation in p latelet adhesion, thrombin generation, or platelet activation. RFGD polymer ization of C3F6 and C2H4 resulted in polymers with varying proportions of f luorinated species, as determined by ESCA. Fibrinogen adsorption from plasm a was maximal on a polymer made with 25% C3F6 (75% C2H4) in the feed. Howev er von Willebrand factor (vWF) adsorption was greater on polymers made with increased %C3F6 in the feed. Platelet adhesion decreased with increasing % C3F6 in the feed. Thrombin generation was lowest for platelets adherent to polymers made from both C3F6 and C2H4. Therefore, procoagulant activity of platelets increased for polymers made with increased %C3F6 in the feed, sim ilar to the trend in VWF adsorption. These findings suggest that increased incorporation of fluorinated species into RFGD polymers leads to decreased platelet adhesion and increased platelet activation (which is possibly due to increased VWF adsorption). (C) 2000 John Wiley & Sons, Inc.