Department of Chemistry, Università degli Studi di Torino, Via P. Giuria 7, 10125 Torino, Italy.
Mater Sci Eng C Mater Biol Appl. 2013 Apr 1;33(3):1132-42. doi: 10.1016/j.msec.2012.12.005. Epub 2012 Dec 10.
A series of Sr-substituted hydroxyapatites (HA), of general formula Ca(10-x)Srx(PO4)6(OH)2, where x=2 and 4, were synthesized by solid state methods and characterized extensively. The reactivity of these materials in cell culture medium was evaluated, and the behavior towards MG-63 osteoblast cells (in terms of cytotoxicity and proliferation assays) was studied. Future in vivo studies will give further insights into the behavior of the materials. A paper by Lagergren et al. (1975), concerning Sr-substituted HA prepared by a solid state method, reports that the presence of Sr in the apatite composition strongly influences the apatite diffraction patterns. Zeglinsky et al. (2012) investigated Sr-substituted HA by ab initio methods and Rietveld analyses and reported changes in the HA unit cell volume and shape due to the Sr addition. To further clarify the role played by the addition of Sr on the physico-chemical properties of these materials we prepared Sr-substituted HA compositions by a solid state method, using different reagents, thermal treatments and a multi-technique approach. Our results indicated that the introduction of Sr at the levels considered here does influence the structure of HA. There is also evidence of a decrease in the crystallinity degree of the materials upon Sr addition. The introduction of increasing amounts of Sr into the HA composition causes a decrease in the specific surface area and an enrichment of Sr-apatite phase at the surface of the samples. Bioactivity tests show that the presence of Sr causes changes in particle size and/or morphology during soaking in MEM solution; on the contrary the morphology of pure HA does not change after 14 days of reaction. The presence of Sr, as Sr-substituted HA and SrCl2, in cultures of human MG-63 osteoblasts did not produce any cytotoxic effect. In fact, Sr-substituted HA increased the proliferation of osteoblast cells and enhanced cell differentiation: Sr in HA has a positive effect on MG-63 cells. In contrast, Sr ions alone, at the concentrations released by Sr-HA (1.21-3.24 ppm), influenced neither cell proliferation nor differentiation. Thus the positive effects of Sr in Sr-HA materials are probably due to the co-action of other ions such as Ca and P.
一系列 Sr 取代的羟基磷灰石（HA），通式为 Ca(10-x)Srx(PO4)6(OH)2，其中 x=2 和 4，通过固态方法合成并进行了广泛的表征。评估了这些材料在细胞培养基中的反应性，并研究了它们对 MG-63 成骨细胞（在细胞毒性和增殖试验方面）的行为。未来的体内研究将进一步深入了解材料的行为。Lagergren 等人（1975 年）的一篇论文，关于通过固态方法制备的 Sr 取代的 HA，报告说 Sr 在磷灰石组成中的存在强烈影响磷灰石的衍射图案。Zeglinsky 等人（2012 年）通过从头计算方法和 Rietveld 分析研究了 Sr 取代的 HA，并报告由于 Sr 的添加，HA 单元体积和形状发生变化。为了进一步澄清 Sr 的添加对这些材料的物理化学性质的作用，我们通过固态方法使用不同的试剂、热处理和多技术方法制备了 Sr 取代的 HA 组合物。我们的结果表明，在此处考虑的水平上引入 Sr 确实会影响 HA 的结构。还有证据表明，随着 Sr 的添加，材料的结晶度降低。随着 HA 组成中 Sr 含量的增加，比表面积降低，表面样品中 Sr-磷灰石相富集。生物活性测试表明，在 MEM 溶液浸泡过程中，Sr 的存在会导致颗粒尺寸和/或形态发生变化；相反，纯 HA 的形态在 14 天的反应后不会发生变化。Sr 作为 Sr 取代的 HA 和 SrCl2 存在于人 MG-63 成骨细胞的培养物中不会产生任何细胞毒性作用。事实上，Sr 取代的 HA 增加了成骨细胞的增殖并增强了细胞分化：HA 中的 Sr 对 MG-63 细胞有积极影响。相反，单独的 Sr 离子，在 Sr-HA 释放的浓度下（1.21-3.24ppm），既不影响细胞增殖也不影响分化。因此，Sr-HA 材料中 Sr 的积极作用可能归因于其他离子（如 Ca 和 P）的共同作用。
