Electrodeposition of hydroxyapatite onto nanotubular TiO2 for implant applications

Titanium and its alloys are being used in many orthopedic and bioimplant applications. In order to render these materials bioactive and to enhance osteointegration, the surfaces are coated with hydroxyapatite (HAp). Adhesion of bone cell to the implant surface, bond strength and durability of the implants are highly dependent upon the characteristics of the Ti substrate and the methods utilized in the hydroxyapatite coating process. In this paper we have reported an innovative method of preparation of a nanotubular titania surface and subsequent electrodeposition of hydroxyapatite nanocrystalline coating. Growth of the hydroxyapatite onto the nanotubular titania surface was accomplished by a pulsed electrodeposition process. Prior to the electrodeposition, the nanotubular titania surface was subjected to an alkaline treatment, which provided a template for nucleation of the hydroxyapatite inside the nanotubes. This process resulted in a vertical growth of the hydroxyapatite crystals and increased the bond strength of the coating. Bond strength was further improved by annealing the hydroxyapatite coated nanoporous titania in an argon atmosphere.