Takadama H, Kim H M, Kokubo T, Nakamura T
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
J Biomed Mater Res. 2001 May;55(2):185-93. doi: 10.1002/1097-4636(200105)55:2<185::aid-jbm1005>3.0.co;2-p.
Bioactive titanium metal, prepared by treatment with NaOH followed by an annealing stage to form a sodium titanate layer with a graded structure on its surface, forms a biologically active bone-like apatite layer on its surface in the body, and bonds to bone through this apatite layer. In this study, process of apatite formation on the bioactive titanium metal in a simulated body fluid was investigated using X-ray photoelectron spectroscopy. The bioactive titanium metal formed Ti-OH groups soon after soaking in the simulated body fluid, via the exchange of the Na(+) ions in the sodium titanate on its surface with H(3)O(+) ions in the fluid. The Ti-OH groups on the metal combined with the calcium ions in the fluid immediately to form a calcium titanate. After a long period, the calcium titanate on the metal took the phosphate ions as well as the calcium ions in the fluid to form the apatite nuclei. The apatite nuclei then proceeded to grow by consuming the calcium and phosphate ions in the fluid. These results indicate that the Ti-OH groups formed on the metal induce the apatite nucleation indirectly, by forming a calcium titanate. The initial formation mechanism of the calcium titanate may be attributable to the electrostatic interaction of the negatively charged Ti-OH groups with the positively charged calcium ions.
通过用氢氧化钠处理并随后进行退火阶段以在其表面形成具有梯度结构的钛酸钠层而制备的生物活性钛金属，在体内其表面形成生物活性骨样磷灰石层，并通过该磷灰石层与骨结合。在本研究中，使用X射线光电子能谱研究了生物活性钛金属在模拟体液中磷灰石形成的过程。生物活性钛金属浸泡在模拟体液中后不久，通过其表面钛酸钠中的Na(+)离子与体液中的H(3)O(+)离子交换，形成了Ti-OH基团。金属上的Ti-OH基团立即与体液中的钙离子结合形成钛酸钙。长时间后，金属上的钛酸钙摄取体液中的磷酸根离子以及钙离子以形成磷灰石核。然后，磷灰石核通过消耗体液中的钙和磷酸根离子而继续生长。这些结果表明，在金属上形成的Ti-OH基团通过形成钛酸钙间接诱导磷灰石成核。钛酸钙的初始形成机制可能归因于带负电荷的Ti-OH基团与带正电荷的钙离子之间的静电相互作用。
