Bioapatite, the main inorganic component of bone, is similar to hydroxyapatite (HAp, Ca₅[PO₄]₃(OH)) having some [CO₃]²⁻ content which plays an important role in leaching/precipitation processes in many biological lesions. We studied the leaching of powdered bovine tibia in soda-saturated (nahcolite, NaHCO₃) water as a function of concentrations and treating periods. The reaction products were characterized by X-ray (XRD) and electron diffraction (SAED) techniques as well as high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS). We found evidence for dissolution of bone and precipitation of Ca-carbonate. The rate of carbonate precipitation was found to be a function of both the mass ratio of nahcolite/bone and the leaching time. According to XRD, calcite formed as a new crystalline phase at the expense of bioapatite. Based on HRTEM images, residual nanocrystalline apatite and unstable Ca-carbonate were also recognised, allowing the reconstruction of the intermediate stages of the leaching process. We propose a reaction sequence for the transformations of bioapatite in carbonated, alkaline media that may contribute to the understanding of the lesion processes of bone.

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碳酸盐饱和水中生物磷灰石的浸出机理

生物磷灰石是骨骼的主要无机成分，类似于具有某些[CO ₃ ] ^2-含量的羟基磷灰石（HAp，Ca ₅ [PO ₄ ] ₃（OH）），在许多生物损伤中的浸出/沉淀过程中起着重要作用。我们研究了在饱和的苏打水（碳酸氢钠，碳酸氢钠₃）水作为浓度和处理时间的函数。通过X射线（XRD）和电子衍射（SAED）技术以及高分辨率透射电子显微镜（HRTEM）和能量分散光谱（EDS）对反应产物进行表征。我们发现了骨溶解和碳酸钙沉淀的证据。发现碳酸盐沉淀的速率是碳酸钙/骨的质量比和浸出时间的函数。根据XRD，方解石形成了一种新的结晶相，但以生物磷灰石为代价。根据HRTEM图像，还可以识别出残留的纳米晶磷灰石和不稳定的碳酸钙，从而可以重构浸出过程的中间阶段。我们提出了碳酸盐中生物磷灰石转化的反应顺序，