School of Chemical Engineering, University of Birmingham, B15 2TT, UK.
Sci Rep. 2016 Sep 8;6:32671. doi: 10.1038/srep32671.
The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco's - Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media.
基于 brushite 的骨水泥的吸收具有高度不可预测性，强烈依赖于许多条件。其中一个主要因素是相转变，向更稳定的相（如羟基磷灰石）的转变会影响吸收速率。尽管其重要性，但相转变的分析主要是通过仅检测晶体成分的方法进行的，这些方法没有提供有关各相空间分布的信息。在这项研究中，共聚焦拉曼显微镜被用于绘制在磷酸盐缓冲盐水、胎牛血清、杜尔贝科最低必需培养基（有和没有血清）中老化的 brushite 圆柱体的横截面。图像图谱显示了老化介质对整个陶瓷结构中相组成的重要性。当在没有血清的情况下老化时，会发生 brushite 相的溶解，同时在样品的外围沉积八钙磷酸盐（OCP）。OCP 的沉积可在五天内检测到，并降低了材料中 brushite 的溶解速率。即使使用 10vol%的血清，也会阻止相转变。本文证明了共聚焦拉曼显微镜在监测生物水泥中相变化的价值；它还表明了在不含血清的介质中评估材料降解时存在的问题。
