Biological effect of nitrogen doped diamond-like carbon films for biomedical applications

Carbon nitride films have received much attention recently because of their desirable properties, similar to diamond-like carbon (DLC) films. Thus we have compared the anti-thrombotic properties of amorphous carbon nitride films and DLC films as potential blood-contacting biomedical materials. In this work, the amorphous carbon nitride films and DLC films were deposited on silicon wafer substrates using a vacuum arc system. Surface thrombogenicity of the two films was evaluated by in vitro tests. An LDH assay was used to examine the platelets attached to the film surfaces. An F1+2 assay was used to evaluate the activation of clotting cascade. The fibrinogen adsorption and its conformational change were also investigated by using an immunoassay technique. The results show that the anti-thrombotic properties of the films were improved by nitrogen doping, This improvement is due to the inhibition of conformational change of adsorbed fibrinogen, preventing the adhesion of platelets and activation of clotting cascade.