Effect of Zn2+ on the Physicochemical Characteristics of Octacalcium Phosphate and Its Hydrolysis into Apatitic Phases
Effect of Zn2+ on the Physicochemical Characteristics of Octacalcium Phosphate and Its Hydrolysis into Apatitic Phases
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DOI：
10.1021/cg1009835
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发表时间：
2011-05-01
影响因子：
3.8
通讯作者：
Suzuki, Osamu
中科院分区：
文献类型：
--
作者：
Honda, Yoshitomo;Anada, Takahisa;Suzuki, Osamu
据报道，锌 (Zn) 离子和 OCP 晶体都是骨形成的兴奋剂。本研究旨在研究锌离子如何影响磷酸八钙（OCP）的沉淀及其水解成磷灰石相的过程。通过共沉淀法或在热水中增强 OCP 水解，获得了含锌磷酸八钙制剂（Zn-CaPs）及其含有不同量 Zn（0.06-0.72 mmol/g）的水解产物（水解 Zn-CaPs）。获得的所有 Zn-CaP 的 Ca/P 摩尔比与化学计量 OCP (1.33) 相似，范围为 1.23 至 1.37。如果在生理溶液（0.1 M HEPES 缓冲液中，pH = 7.4，37 摄氏度）中孵育，Zn-CaP 也表现出与原始 OCP 类似的溶解行为。水解样品的 X 射线衍射分析表明，原始 OCP 转化为结晶羟基磷灰石，在 2 theta = 10.8 度处具有特定峰，而含 Zn 高于 0.18 mmol/g 的 Zn-CaPs 即使在超过 25 小时的水解时间后仍保留无定形结构。这些结果表明，Zn 离子延迟了 OCP 向磷灰石的水解过程，从而促进了无定形结构的形成。
Zinc (Zn) ions and OCP crystals have both been reported to be stimulants for bone formation. The present study was designed to investigate how Zn ion affects the precipitation of octacalcium phosphate (OCP) and its hydrolysis process into apatitic phases. Zn-containing octacalcium phosphate preparations (Zn-CaPs) and their hydrolysates (hydrolyzed Zn-CaPs) containing various amounts of Zn (0.06-0.72 mmol/g) were obtained either through a co-precipitation method or by enhancing the OCP hydrolysis in hot water. All of the Zn-CaPs obtained had Ca/P molar ratios similar to that of stoichiometric OCP (1.33), ranging from 1.23 to 1.37. Zn-CaPs also exhibited similar dissolution behavior to that of original OCP if incubated in a physiological solution (in the 0.1 M HEPES buffer, pH = 7.4, 37 degrees C). X-ray diffraction analysis of the hydrolyzed samples showed that original OCP converted to the crystalline hydroxyapatite with a specific peak at 2 theta = 10.8 degrees, while Zn-CaPs containing Zn above the 0.18 mmol/g retained the amorphous-like structure even after a greater than 25 h hydrolysis period. These results indicate that Zn ions retarded the hydrolysis process of OCP toward apatite, resulting in enhanced formation of the amorphous-like structure.