Adsorptive properties of albumin, fibrinogen, and γ-globulin on fluorinated diamond-like carbon films coated on PTFE

Fluorinated diamond-like carbon (F-DLC) films were deposited on polytetrafluoroethylene (PTFE) using radio frequency (RF) plasma-enhanced chemical vapor deposition (CVD) by changing the ratio of tetrafluoromethane (CF4) and methane (CH4). To enhance the adhesion strength of the F-DLC film to the PTFE substrate, the PTFE surface was modified with a N-2 plasma pre-treatment. XPS analysis of the films showed that the C-C bond decreased with increases in the CF4 ratio, whereas the C-F bond increased with the CF4 ratio. The F/C ratio of the film also increased with the CF4 ratio. The pull-out test showed that the adhesion strengths of the films (CF4-0-60%) were improved with the plasma pre-treatment. In the film without the plasma pre-treatment, adhesion strength increased with the CF4 ratio. In contrast, in the case with the plasma pre-treatment, the adhesion strength of the F-DLC film decreased with the increased CF4 ratio. Regarding the adsorption of albumin, fibrinogen, and gamma-globulin, the amount of adsorbed albumin on the film decreased with an increasing CF4 ratio, and the amount of adsorbed fibrinogen and gamma-globulin increased with the CF4 ratio. The CF4-0% DLC film showed the most adsorbed albumin and the least adsorbed fibrinogen and gamma-globulin. This indicates that the CF4-0% DLC film has higher anti-thrombogenicity than the F-DLC film.