Initial platelet adhesion and platelet shape on polymer surfaces with different carbon bonding characteristics (anin vitro study of Teflon, Pellethane and XLON intravenous cannulae)

Abstract

Two commercially available intravenous catheters (i.d. 1.2 mm), made of polytetrafluoroethylene (PTFE, Teflon) and a thermoplastic polyurethane-polytetramethylene glycol block-copolymer (TPEU, Pellethane D-65), and a catheter made of a new test material, a polyamide-polyethylene glycol block-copolymer (XLON D-60), were compared with respect to surface chemistry, platelet adhesion and platelet shape changein vitro. Surface chemistry was evaluated by X-ray photoelectron spectrosopy. High-resolution carbon peaks were obtained at 15 and 90° take-off angle. The hydrophilicity was determined by measuring capillary rise in the catheters with distilled water. Platelet adhesion and platelet shape changes on the catheter surfaces were examinedin vitro, in a system without blood-air interface, and visualized by scanning electron microscopy. The degree of hydrophilicity of the materials appeared to be related to the relative ether carbon content of their outermost surfaces. The platelet adhesion was low on hydrophilic surfaces (XLON) and increased with decreasing hydrophilicity on the more hydrophobic surfaces (TPEU and PTFE). The degree of shape change of the adhered platelets also increased with decreasing hydrophilicity. Changes in surface chemistry caused by toluene extraction of the TPEU significantly decreased platelet adhesion and the degree of shape change in parallel with an increased ether carbon content of the surface.