Hydroxyapatite growth on anodic TiO2 nanotubes

Abstract

In the present work, we study the growth of hydroxyapatite formation on different TiO2 nanotube layers. The nanotube layers were fabricated by electrochemical anodization of titanium in fluoride-containing electrolytes. To study various nanotube lengths, layers with an individual tube diameter of 100 nm were grown to a thickness of approximately 2 μm or 500 nm. The ability to form apatite on the nanotube layers was examined by immersion tests combined with SEM, XRD and FT-IR investigations. For reference, experiments were also carried out on compact anodic TiO2 layers. The results clearly show that the presence of the nanotubes on a titanium surface enhances the apatite formation and that the 2-μm thick nanotube layer triggers deposition faster than the thinner layers. Tubes annealed to anatase, or a mixture of anatase and rutile are clearly more efficient in promoting apatite formation than the tubes in their "as-formed" amorphous state. © 2006 Wiley Periodicals, Inc.