Study on the performance enhancement of biomedical implants: in vitro test under UV irradiation of titanium anodised in mixed electrolyte

Titanium (Ti) recently has widely been used in the biomedical applications due to its high performance. Therefore, surface modifications of titanium have attracted a lot of interest to provide better osseointegration. Ti was subjected to anodic oxidation process and in vitro testing to assess the bioactivity of titanium oxide (TiO2) coating. TiO2 coating has been anodised at room temperature in different electrolyte; in sulphuric acid (H2SO4); phosphoric acid (H3PO4); and a mixture of H2SO4 and H3PO4 acids. The parameters used in anodization were: concentration of the electrolytes, applied voltage and current density. The coated surface is then evaluated using different testing techniques; the microstructure using scanning electron microscope (SEM); the elemental analysis using Energy-dispersive x-ray spectroscopy (EDX); mineralogical and crystal structure using x-ray diffraction (XRD); absorption analysis using Fourier transform infrared spectroscopy (FT-IR); and the hydrophilicity using water contact angle (WCA). TiO2 was then subjected in vitro testing to assess the bioactivity of TiO2 surface; that is the apatite formation ability. The apatite formation of the TiO2 coating was precipitated by using simulated body fluid (SBF) in the dark and under the ultraviolet (UV) irradiation to mimic the reactions that may occur with the human bone-like cells layer. The testing was done to evaluate the apatite’s microstructure, mineralogy, elements and absorption. From the results it was found that higher apatite was obtained with the increased of the immersion time; higher apatite formation and crystallization was found at earlier time of immersion for the TiO2 that was immersed in SBF under the UV; higher apatite was obtained on the TiO2 coatings that were anodised in H2SO4, H3PO4 and mixture electrolyte at lower electrolyte concentration. The increased apatite on these coatings can be related to the strong Ti-O- functional groups on the coating surface. The highest apatite was obtained on the TiO2 coating that was anodised in a mixture electrolyte that has obtained Ti-OH functional group. The UV has resulted in the increased Ti-O- and Ti-OH groups, thus higher apatite precipitation ability