A study of biotribological behavior of DLC coatings and its influence to human serum albumin

Diamond-like carbon (DLC) coatings has been synthesized on NiTi alloy substrates by arc enhanced magnetic sputtering (AEMS) system using graphite targets. The tribological behavior indicates that the friction coefficient and wear rate of DLC coatings deposited on NiTi alloy substrates is relatively higher in ambient air than that in simulated body fluid (SBF). In human serum albumin (HSA) solution, though the friction coefficient is higher than that in SBF, but it has quite low wear rate. The Raman spectrum shows that the low friction coefficient of DLC coatings is due to the graphitization during sliding, and the degree of graphitization is relatively lower in both SBF and HSA solution than them in ambient air. The friction mechanism of DLC coatings at different environments is then proposed. On the other hand, the kinematic viscosity and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) measurements show that the DLC coatings cannot induce the thermal and mechanical denaturation of HSA during sliding.