Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
J Biomed Mater Res B Appl Biomater. 2011 Jan;96(1):1-8. doi: 10.1002/jbm.b.31749.
Hydroxyapatite coatings were deposited on the titanium substrate by using various content Na₃Cit as an organic modifier in electrolytes. The influence of the Na₃Cit on the sizes of the HA crystals during electrolytic deposition was investigated under different molar ratio of Na₃Cit to calcium ions. The experimental results showed that the size of HA crystal was well controlled by the addition of Na₃Cit. When the molar ratio of Na₃Cit to calcium ions was equal or greater than five, the obtained HA coating consisted of nanosized crystals. The HA nanoparticles were precipitated without a precursor phase when the molar ratio of Na₃Cit to calcium ions was five; otherwise, the CaP coating experienced a phase conversion from octacalcium phosphate (OCP) to HA during the ELD. The effect of pH on saturation indexes with respect to hydroxyapatite, OCP, and dicalcium dihydrogen phosphate of these electrolytes was calculated by a computer program PHREEQC. The calculation showed the nucleation of OCP as the precursor during the deposition could be inhibited with increasing Na₃Cit content in the electrolytes.
采用不同浓度的柠檬酸三钠（Na₃Cit）作为有机添加剂在电解液中在钛基体上沉积羟基磷灰石（HA）涂层。研究了在不同的柠檬酸三钠与钙离子摩尔比下，柠檬酸三钠对电沉积过程中 HA 晶体尺寸的影响。实验结果表明，通过添加柠檬酸三钠可以很好地控制 HA 晶体的尺寸。当柠檬酸三钠与钙离子的摩尔比等于或大于 5 时，得到的 HA 涂层由纳米级晶体组成。当柠檬酸三钠与钙离子的摩尔比为 5 时，HA 纳米颗粒在没有前驱体相的情况下沉淀；否则，在 ELD 过程中，CaP 涂层经历了从八钙磷酸（OCP）到 HA 的相转变。通过计算机程序 PHREEQC 计算了这些电解液中关于羟基磷灰石、OCP 和磷酸二氢钙的饱和度指数对 pH 的影响。计算表明，随着电解液中柠檬酸三钠含量的增加，可以抑制 OCP 作为前驱体的成核。
