Mechanism and kinetics of apatite formation on nanocrystalline TiO2 coatings: a quartz crystal microbalance study.
Mechanism and kinetics of apatite formation on nanocrystalline TiO2 coatings: a quartz crystal microbalance study.
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DOI：
10.1016/j.actbio.2007.10.003
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发表时间：
2008-05
影响因子：
9.7
通讯作者：
Zhengpeng Yang;S. Si;Xiaoming Zeng;Chun-jing Zhang;Hongjuan Dai
中科院分区：
文献类型：
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作者：
Zhengpeng Yang;S. Si;Xiaoming Zeng;Chun-jing Zhang;Hongjuan Dai
磷灰石（Ca5(PO4)3OH）一直被认为是一种促进骨修复和种植的优秀生物材料。采用原位石英晶体微天平（QCM）、扫描电镜（SEM）、傅里叶变换红外光谱（FTIR）、x射线衍射（XRD）和能量色散x射线能谱（EDX）等技术，研究了负电荷纳米tio2涂层在模拟流体（SBF）中诱导磷灰石的形成，并详细讨论了pH、tio2颗粒大小和tio2涂层厚度等影响磷灰石形成的因素。在磷灰石沉淀过程中明显观察到两个不同的阶段，表明两个不同的动力学过程。在第一阶段，SBF中的钙离子首先被吸引到带负电荷的tio2表面，然后在界面处与磷酸离子结合形成钛酸钙，形成磷灰石核。成核后，过饱和SBF中的钙离子、磷酸盐离子和其他次要离子（即co32和Mg2+）自发沉积在原始磷灰石涂层上，形成磷灰石沉淀。在原位频移方面，分别估算了磷灰石（k1和K2）在两个不同阶段的生长速率常数，在1.5SBF溶液中分别为（1.96±0.14）×10−3s−1和（1.28±0.10）×10−4s−1。结果表明，第一阶段的反应速率明显高于第二阶段。
Apatite (Ca5(PO4)3OH) has long been considered as an excellent biomaterial to promote bone repairs and implant. Apatite formation induced by negatively charged nanocrystalline TiO2coatings soaked in simulated body fluid (SBF) was investigated using in situ quartz crystal microbalance (QCM), scanning electron microscopy (SEM), Fourier-transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) techniques, and factors affecting its formation such as pH, size of TiO2particles and thickness of TiO2coatings, were discussed in detail. Two different stages were clearly observed in the process of apatite precipitation, indicating two different kinetic processes. At the first stage, the calcium ions in SBF were initially attracted to the negatively charged TiO2surface, and then the calcium titanate formed at the interface combined with phosphate ions, consequently forming apatite nuclei. After the nucleation, the calcium ions, phosphate ions and other minor ions (i.e. CO32-and Mg2+) in supersaturated SBF deposited spontaneously on the original apatite coatings to form apatite precipitates. In terms of the in situ frequency shifts, the growth-rate constants of apatite (K1and K2) were estimated, respectively, at two different stages, and the results were (1.96±0.14)×10−3s−1and (1.28±0.10)×10−4s−1, respectively, in 1.5SBF solution. It was found that the reaction rate at the first stage is obviously higher than that at the second stage.