In vitro apatite deposition on titania film derived from chemical treatment of Ti substrates with an oxysulfate solution containing hydrogen peroxide at low temperature

Thin titania film consisting of anatase and rutile was deposited on Ti substrates when soaked in a TiOSO₄/H₂O₂ solution and aged in hot water. H₂O₂ corroded the Ti substrates, yielded a porous surface, and kept the solution from peptization. Thicker titania layers were formed in favor of both a greater supersaturation of Ti(IV) in the solution and a higher concentration of hydrated Ti(IV) derived by the corrosion of Ti and the hydrolysis of TiOSO₄. The effects of aging in hot water were accounted for as they caused structural relaxation of the surface layer involving a rearrangement of Ti-OH and eliminating residual species like peroxide ions. Those titania layers were thus favored to deposit apatite when the Ti substrates were placed under a body environment, i.e. soaked in a simulated body fluid of Kokubo's recipe.