Bioactive Ca10(PO4)6(OH)2−TiO2 composite coating prepared by sol-gel process

The sol-gel prepared titania (TiO₂) has recently been demonstrated with a promising bioactivity 1]. It forms a chemical bond with the living bone in the body, although the bonding is not very strong. The present study is intended to improve the bone-bonding ability of the titania gel. The goal is achieved by impregnating the titania with hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂). The processing route includes the following steps: (1) the titania sol solution was prepared; (2) the solution was mixed with fine hydroxyapatite (HA) powders; (3) the mixture was used to produce a coating on a commercial pure titanium (c.p. Ti) or Ti6A14V plate by a dip coating technique; (4) the coating was fired at 400–600°C. The resulting coating is a composite consisting of hydroxyapatite embedded in the matrix of the titania gel. Such HA-TiO₂ composite coating is capable of inducing the hydroxyapatite precipitation from a simulated body fluid. When implanted in femurs of goat, the composite coating shows a bonding with bone. Its bone-bonding strength is twice as high as that of the pure titania gel coating. The results indicate that impregnating with hydroxyapatite is a promising way to increase the bioactivity of the titania gel.