The influence of nanoporous anodic titanium oxide substrates on the growth of the crystalline hydroxyapatite coatings

In this study we investigate the effect of the nanoporous anodic titanium oxide substrate on the morphology and uniformity of hydrothermally precipitated hydroxyapatite coatings. Nanotubular TiO2 substrates were synthesized on a titanium plate by anodic oxidation and subsequently annealed at 500 °C or 600 °C to create the crystalline anatase and/or rutile forms of TiO2. The substrates were further used for HAp growth under hydrothermal conditions. The samples were then characterized with the XRD, Raman and SEM techniques. The results show that hydrothermal synthesis leads to formation of needle-like coating layer of HAp particles. The diameter and length of HAp crystals decrease with increasing annealing temperature of TiO2 nanotubular arrays. Furthermore, we demonstrate that nanostructured surface of titanium oxide has beneficial influence on the HAp nucleation and coverage.