A functionalised carbon nanotube-gelatin-Zn doped HA composite coating for bone grafting application

To improve the surface bioactivity of carbon/carbon composites, functionalized carbon nanotube-gelatin-Zn doped hydroxyapatite (FIC-GL-ZnH) composite coatings were fabricated on carbon/carbon composites by a combination method of chemical vapor deposition, soaking and electrochemical deposition method. The morphology, bonding strength and in-vitro bioactivity of composite coating were investigated. Results showed that the functionalized carbon nanotube-gelatin could not only bond with the carbon/carbon composite substrate tightly by in-situ grown mode but also provide a three-dimensional network structure for the infiltration of Zn doped hydroxyapatite. The FIC-GL-ZnH coating with spherical shape had excellent bonding strength, which was about 2.3 times higher than that obtained for Zn doped hydroxyapatite coating. In-vitro bioactivity test demonstrated that the FIC-GL-ZnH coating could induce the formation of bone-like apatite with particle shape, exhibiting good in-vitro bioactivity. It was suggested that the FIC-GL-ZnH coating might be an effective method to improve the surface bioactivity of carbon/carbon composites.