Biomimetic coating on pure titanium submitted to different surface treatments

Titanium (Ti) plates were firstly treated to form various types of oxide layers on the surface and then immersed into simulated body fluid (SBF) to evaluate the apatite forming ability. The surface morphology and roughness of the different oxide layers were measured by atomic force microscopy (AFM), and the surface energies were determined based on the Owens-Wendt (OW) methods. It was found that Ti samples after Alkali-Heat treatment (AH) achieved the best apatite formation after soaking in SBF for 3 weeks, compared to those without treatment, thermal or H₂O₂ oxidation. Furthermore, contact angle measurement revealed that the oxide layer on the alkali-heat treated Ti samples possessed the highest surface energy. The results indicate that the apatite inducing ability of a titanium oxide layer is linked to its surface energy. Apatite nucleation is easier on a surface with a higher surface energy.