Synthesis of the mesoporous TiO2 array for hydroxyapatite precipitation

In this study, the preparation of mesoporous TiO2 was based on an evaporation-induced self-assembly (EISA) method that used Pluronic P123 as the structure-directing agent and TBOT as the titanium source. We added TBOT to the P123 surfactant that was dissolved in ethanol and then added HCl to this mixed solution with stirring at 25 °C. Then, the thin film of sol was prepared on the Ti substrate through spin-coating. The result was allowed to be sampled in an open Petri dish as it underwent solvent evaporation at 40 RH% and 35 °C for 24 h, and then the samples were calcined for 1 h at various temperatures from 150 to 450 °C. Finally, the mesoporous TiO2 array was formed on the Ti substrate. The mesostructures of the samples were characterized by a small angle X-ray diffraction on the 13A1 beam line at the National Synchrotron Radiation Research Center (NSRRC, Taiwan). The result demonstrates that the sample prepared with a P123/TBOT mole ratio of 0.6 clearly shows a main peak at 0.2° to 0.25°, thus revealing the presence of a hexagonal phase mesostructure. The mesoporous TiO2 film calcined at various temperatures between 150 and 450 °C revealed that the calcination temperature of 250 °C is the optimal temperature for the ordered mesoporous TiO2 that grew on the Ti substrate. The microstructures revealed that the tubular mesopores are arrayed on the Ti substrate. In vitro bioactivity appraisement results show that apatite was formed on the coating surface after immersion in simulated body fluid (SBF) for 3 weeks, which indicates that the mesoporous film has the potential for chemical bonding with bone tissue after being implanted into an animal body.