Synthesis of titanium nitride-coated titanium dioxide nanotubes and an investigation into their compatibility with human gingival fibroblasts

Abstract Titanium nitride (TiN) coatings substantially enhance substrate biocompatibility and promote cellular functions. In this study, TiN coating was deposited on the surfaces of titanium dioxide (TiO 2 ) nanotubes via atomic layer deposition to fabricate TiN-TiO 2 nanotube composites and investigate their cytocompatibility with human gingival fibroblasts (HGFs). The surface morphology, roughness, wettability, chemical composition, binding strength, and surface hardness of the TiN–TiO 2 nanotubes were characterised. Protein adsorption and elution properties were assessed. The effect of TiN–TiO 2 nanotubes on HGFs cellular functions was systematically investigated. Nanotube morphology was well preserved after TiN coating. Compared with TiO 2 nanotubes, TiN–TiO 2 nanotubes exhibited a smaller nanotube diameter, reduced hydrophilicity, increased surface roughness, enhanced binding strength and hardness, and improved protein adsorption capacity and sustained-release performance. They significantly enhanced the survival, proliferation, and adhesion capabilities of HGFs while upregulating the expression levels of relevant proteins and genes. Our results reveal that TiN–TiO 2 nanotubes exhibit superior cytocompatibility and significantly promote HGFs cellular functions. This indicates that TiN-TiO 2 nanotubes have considerable potential for improving the integration of implant abutments with gingival fibroblasts and for enhancing the soft tissue seal.