Biocompatibility evaluation of DLC-coated Si3N4 substrates for biomedical applications

DLC coatings are of enormous interest for biotribological applications due to their biocompatibility, auto-lubricious, and non-stick properties. The most demanding implant is the hip joint. Alternative materials to metal alloys are being increasingly investigated aiming low wear debris volume, in any case innocuous wear particles. Silicon nitride (Si3N4) ceramics are light, tough, mechanical resistant, inert materials, turning them suitable for high-load medical applications. In this study, Si3N4 polished substrates were coated with adherent DLC coatings grown by DC magnetron sputtering to reduce of the friction forces against any antagonist material. Surface characterization results showed that the developed material is quite hydrophobic, with a total surface tension of 45.7 mN/m (polar component: 9.1 mN/m; dispersive component: 36.6 mN/m), and a zeta potential of −35.0±1.3 mV. In vitro testing using an acellular simulated body fluid (SBF) showed no apatite layer formation ability, as confirmed by SEM observation and analysis of the solution ions concentration with immersion time. MG63 osteoblast-like cells showed poor adhesion on the DLC films but the adherent cells displayed a normal morphology and, as compared to standard polystyrene tissue culture plates, exhibited a higher cell growth rate, suggesting no indication of cytotoxicity. Results suggested that the novel DLC-coated Si3N4 biomaterial should be adequate to be used for articular prostheses medical application. © 2007 Elsevier B.V. All rights reserved.