Abstract

Hydroxyapatite nanoparticles (NPs) have been synthesized by controlled precipitation in the presence of a surfactant, sodium dodecyl sulfate. The sizes, shapes, and structures of the NPs depend on the sequence of mixing the reagents . When the addition of sodium phosphate to a surfactant solution is followed by the addition of calcium nitrate, rodlike hydroxyapatite NPs are formed, the length of which decreases with a rise in surfactant concentration. As the sodium dodecyl sulfate concentration increases, the ζ-potential of the NPs decreases to zero; then, its absolute value grows to –55 mV. This suggests that a surfactant bilayer is formed on the NP surface, with the bilayer shielding the surface of the growing crystals. The shielding leads to the formation of smaller NPs at high surfactant concentrations. When the addition of calcium nitrate to the surfactant solution is followed by the addition of sodium phosphate, the synthesis most likely occurs on the surface of micelles, which partially consist of calcium dodecyl sulfate. Therefore, the sulfate phase remains preserved in the synthesized particles, which is confirmed by X-ray diffraction analysis. At higher surfactant concentrations in the reaction medium, the presence of flexible cylindrical micelles is possible. The precipitation of hydroxyapatite on the surface of such micelles results in the formation of wavy threadlike particles.

中文翻译：

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十二烷基硫酸钠存在下控制沉淀法合成羟基磷灰石纳米粒子

摘要

在表面活性剂十二烷基硫酸钠的存在下，通过控制沉淀合成了羟基磷灰石纳米颗粒（NPs）。NP的大小，形状和结构取决于试剂混合的顺序。当在表面活性剂溶液中添加磷酸钠后，再添加硝酸钙时，会形成棒状羟基磷灰石NP，其长度随着表面活性剂浓度的增加而减小。随着十二烷基硫酸钠浓度的增加，NPs的ζ电位降低至零；然后，其绝对值增加到–55 mV。这表明在NP表面上形成了表面活性剂双层，该双层屏蔽了正在生长的晶体的表面。屏蔽导致在高表面活性剂浓度下形成较小的NP。当在表面活性剂溶液中添加硝酸钙后，再添加磷酸钠时，合成很可能发生在部分由十二烷基硫酸钙组成的胶束表面。因此，硫酸盐相保留在合成颗粒中，这通过X射线衍射分析证实。在反应介质中较高的表面活性剂浓度下，可能存在柔性圆柱状胶束。羟基磷灰石在这种胶束表面上的沉淀导致形成波浪状线状颗粒。X射线衍射分析证实了这一点。在反应介质中较高的表面活性剂浓度下，可能存在柔性圆柱状胶束。羟基磷灰石在这种胶束表面上的沉淀导致形成波浪状线状颗粒。X射线衍射分析证实了这一点。在反应介质中较高的表面活性剂浓度下，可能存在柔性圆柱状胶束。羟基磷灰石在这种胶束表面上的沉淀导致形成波浪状线状颗粒。