Surface and interface analysis of hydroxyapatite/TiO2 biocompatible structures

The properties of hydroxyapatite (HAP) coatings deposited onto sol-gel derived TiO2 coatings are evaluated for applications involving the enhancement of biocompatible prostheses. HAP coatings were initially characterized by X-ray diffraction (XRD) to confirm the absence of calcium phosphate phases with lower stability at physiological pH. The surfaces of these HAP/TiO2 structures were subsequently analyzed in a two-fold manner. A morphologic evaluation of the microstructured surface was made by using atomic force microscopy (AFM) before and after a chemical etching process in acetic acid. Furthermore, the HAP/TiO2 interface composition could be analyzed in depth by using Auger electron spectroscopy (AES). In the case of structures grown onto TiAlV alloys, the composition profiles confirm the presence of apatite nuclei onto the surface, even after etching in acidic conditions. The properties derived from these analyses support the suitability of these structures for the development of orthopedic devices