Investigation of silicon carbon nitride nanocomposite films as a wear resistant layer in vitro and in vivo for joint replacement applications.

Silicon-contained CNx nanocomposite films were prepared using the ion beam assisted magnetron sputtering under different nitrogen gas pressure. With increase of the nitrogen pressure, silicon and nitrogen content of the CNx films drastically increase, and is saturated as the PN2 reach about 40%. Surface roughness and the contact angle are increase, while the friction coefficient decreased. The CNx film with 5.7at.% Si content possess the lowest friction coefficient of only 0.07, and exhibited the best tribological properties. The impact of CNx films with different silicon content on the growth and the activation of osteoblasts were compared to that of Ti6Al4V. The incorporation of silicon in the CNx film also showed an increase cell adhesion. Bonding structure and surface energy were determined to be the factors contributing to the improved biocompatibility. Macrophages attached to 5.7at.% Si contained CNx films down regulated their production of cytokines and chemokines. Moreover, employed with Si contained CNx coated joint replacements, which were implanted subcutaneously into Sprague-Dawley mice for up to 36days, the tissue reaction and capsule formation was significantly decreased compared to that of Ti6Al4V. A mouse implantation study demonstrated the excellent in vivo biocompatibility and functional reliability of wear resist layer for joint replacements with a Si doped a-CNx coating for 36days.