Biocompatibility of Doped Diamond-Like Carbon Coatings for Medical Implants

Diamond-like carbon (DLC) has been established as a very favourable coating for joint prosthetics due to its low friction, high corrosion resistance and biocompatibility. The addition of dopants allows for the modification of several physical properties of DLC, whose relations to biocompatibility have not yet been thoroughly investigated. We studied the properties of a-C:H layers deposited on TiAl6V4 by the plasma immersion ion implantation and deposition (PIII&D) technique. Physical analysis performed comprises the range of attainable compositions [obtained by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection analysis (ERDA)] and structures [by Raman Spectroscopy and energy filtered transmission electron microscopy (EFTEM)] for the cases of the dopants N, Si and TiOx. The biocompatibility assessments were performed in vitro, utilizing human osteoblasts. Cellular proliferation was measured by means of DNA quantification. Osteogenic differentiation was investigated by screening alkaline phosphatase activity and mineralization of cultures. The results demonstrate that highly biocompatible and wear-resistant coatings on complex formed implant surfaces can be efficiently fabricated utilizing PIII&D.