PDF(Pubmed)
Abstract：
The in vitro demineralization of bone tissue is used for simulating the osteoporosis related bone loss. This way would be helpful in observations of bone apatite dissolution in microstructural level and may give significant input for understanding crystal-chemistry of bone resorption. In the case of cortical bone, demineralization occurs inhomogeneously, with the formation of a superficial demineralized layer and a transition zone with a gradient of concentration and structural characteristics perpendicular to the reaction advance front. Changes in the microstructural parameters of the bone mineral in this interface zone are of great interest for understanding the resorptive processes in the bone associated with osteoporosis. In this work, the SEM-EDX method was used to estimate the sizes of the demineralized and interface layers in the cortical bone during stepwise demineralization in HCl water solution; the general patterns of changes in the concentrations of Ca, P, and Cl in these layers were established. The calculations of the effective penetration depth of X-rays in diffraction mode for the intact and partially demineralized cortical bone were performed. It is shown that the use of CoKα radiation (instead of the usual CuKα) ensures the depth of probing within the interface zone, which allows to adequately assess the microstructural parameters (crystallite sizes and lattice microdeformations) of altered bioapatite in the zone of its interaction with an acid agent. A nonmonotonic change in the average size of crystallites and microdeformations of the apatite lattice was revealed during acid demineralization of the bone. Using asymmetric XRD geometry, the evidence was obtained that the affected mineral of the transition zone does not contain other crystalline phases except for weakly crystallized apatite. For the first time, the depth-controlled XRD analysis was applied to such a complex (surface-gradient) object as partially demineralized cortical bone. Additionally, we propose a rapid, averaging, and non-destructive method for estimating the depth of the reaction front dividing the demineralized and non-demineralized portions of the bone by XRD. The consistency of XRD and SEM-EDX data on the thickness values of the demineralized layer is shown.
摘要：
骨组织的体外脱矿质用于模拟骨质疏松症相关的骨丢失。这种方式将有助于观察微结构水平的骨磷灰石溶解，并可能为理解骨吸收的晶体化学提供重要的输入。在皮质骨的情况下，去矿质不均匀发生，形成表面去矿质层和过渡区，其浓度梯度和结构特征垂直于反应前进锋。该界面区中骨矿物质的微观结构参数的变化对于理解与骨质疏松症相关的骨吸收过程非常重要。在这项工作中,SEM-EDX方法用于估算在HCl水溶液中逐步脱矿质过程中皮质骨的脱矿质层和界面层的大小；Ca浓度变化的一般模式，P,在这些层中建立Cl。对完整和部分脱矿的皮质骨进行了衍射模式下X射线的有效穿透深度的计算。表明，使用CoKα辐射（而不是通常的CuKα）可以确保界面区域内的探测深度，可以充分评估改变的生物磷灰石在其与酸剂相互作用的区域中的微观结构参数（微晶尺寸和晶格微变形）。在骨骼的酸脱矿质过程中，微晶的平均尺寸和磷灰石晶格的微变形发生了非单调变化。使用不对称的XRD几何结构，获得的证据表明，过渡区的受影响矿物除了弱结晶磷灰石外，不包含其他结晶相。第一次,将深度控制的XRD分析应用于诸如部分去矿质皮质骨的复杂(表面梯度)对象。此外,我们提出了一个快速的，平均，和非破坏性方法，用于通过XRD估计将骨骼的去矿化部分和非去矿化部分分开的反应前沿的深度。显示了XRD和SEM-EDX数据对去矿层厚度值的一致性。
