Calcium ion modification of TiO2 nanotube arrays to enhance apatite formation

Abstract

Highly ordered TiO2 nanotube arrays were fabricated by anodisation of titanium, and then anodic TiO2 nanotubes were modified in calcium ion-containing solution using ultrasound-assisted impregnation. For reference, the experiments were also carried out by conventional impregnation. The ability to form apatite on specimens was examined upon exposure to modified simulated body fluids combined with FESEM, EDS, XRD, FTIR and Zeta potential investigations. The results reveal that it had a negligible effect on the morphology of nanotubes with varying calcium source and impregnation time using conventional impregnation. Nevertheless, TiO2 nanotubes were modified by the method of ultrasound-assisted impregnation, the mouth of nanotubes became glossy, the diameter of nanotubes became non-uniform and the amount of adsorbate in the inner wall of nanotubes increased. The calcium ion-modified nanotubes were more efficient in promoting apatite formation than the unmodified nanotubes, which may be attributed to the release of calcium ions and the significantly high amount of Ti–OH groups on its surface.