Ion beam modification of ePTFE for improving the blood compatibility

Expanded polytetrafluoroethylene (ePTFE), which is a durable biomaterial because of its excellent biological inertness, is now widely used for prostheses in clinical medicine. However, conversely, the inert nature of ePTFE results in poor adaptability to the surrounding tissue due to lack of a cell-adhesive property. In this study, the surface of ePTFE was modified with ion beam irradiation to improve the blood compatibility. The surface modification of ePTFE sheets by He+, Ne+, Ar+ and Kr+ ion beams was performed at an energy of 150 keV with fluences of 1 × 1014, 5 × 1014 and 1 × 1015 ions/cm2. To investigate anti-thrombogenicity, Ca2+-replenished platelet-rich plasma (PRP) was placed in contact with the surfaces for 10 min. Compared to the non-modified ePTFE surface, platelet response was inhibited on the surfaces modified with He+, Ne+ and Ar+: 5 × 1014 and 1 × 1015 ions/cm2, and Kr+: 5 × 1014 ions/cm2; however, platelet response was promoted on the surfaces modified with He+, Ne+ and Ar+: 1 × 1014 ions/cm2, and Kr+: 1 × 1014 and 1 × 1015 ions/cm2. The significant morphological changes in ePTFE surface associated with ion beam modification are thought to be one of the reasons for the inhibition of platelet response. Endothelial cells were cultured on the surfaces for 3 days to evaluate the cellular response. Endothelial cell growth was significantly promoted on all of the surfaces of ion beam-modified ePTFE, although the non-modified ePTFE surface dramatically inhibited this growth. It is concluded that ion beam modification of ePTFE surface can improve the blood compatibility through not only the promotion of endothelial cell growth but also the inhibition of platelet response.