Hydroxyapatite-TiO2 hybrid coating on Ti implants.

A hydroxyapatite (HA)-titania (TiO(2)) hybrid coating is developed to improve the biocompatibility of titanium (Ti) implants. The HA predeposited layer on Ti via electron beam (e-beam) evaporation is subsequently treated by micro-arc oxidation (MAO) to produce an HA-TiO(2) hybrid layer on Ti. The e-beam-deposited HA layer has a thickness of approximately 1 microm and was highly dense prior to MAO. By means of MAO treatment, a rough and porous TiO(2) layer is formed beneath the HA layer with a simultaneous local dissolution of the HA layer. Due to the HA precoating, high concentrations of Ca and P are preserved on the coating surface. The osteoblast-like cells on the hybrid coating layer grow and spread favorably. The cell proliferation rate on the hybrid coatings is not much different from that on pure Ti or simple MAO-treated Ti. However, the alkaline phosphatase (ALP) activity of the cells is significantly higher (p < 0.05) on the HA-TiO(2) hybrid coatings than on either the pure Ti or the simple MAO-treated specimen, suggesting that the cellular activity on the hybrid coatings is improved.