Eanes E D
Calcif Tissue Res. 1976 Apr 13;20(1):75-89. doi: 10.1007/BF02546399.
The in vitro formation of calcium phosphates from supersaturated solutions seeded with apatite was examined. Reaction kinetics were followed by monitoring solution Ca, Mg, and PO4. Seeds and reaction products were examined chemically and by X-ray diffraction and electron microscopy. Under conditions where amorphous calcium phosphate (ACP) normally precipitates spontaneously, apatite reduced the amount of free ACP formed with a considerable fraction of the Ca and PO4 initially removed from solution depositing directly onto the seeds. At sufficiently great seed concentrations all initial solution losses occurred by this latter route with no free ACP precipitating. These initial events were followed by seed-induced formation of new apatite crystals accompanied by further losses in solution Ca and PO4. Supersaturated solutions stable to spontaneous ACP formation underwent similar losses in solution Ca and PO4 when seeded with apatite. Initial decrease in these ions was instantaneous and proportional to the seed concentration. Subsequent ion removal exponentially decreased with time and correlated with the formation of new apatite crystals overlaying the original seeds. In seeding experiments using physiologically-balanced salt solutions, the initial deposit formed on the seed surface was a magnesium stabilized calcium carbonate phosphate phase. This stable surface phase did not prevent the secondary crystallization of apatite from occurring.
研究了以磷灰石为晶种的过饱和溶液中磷酸钙的体外形成过程。通过监测溶液中的钙（Ca）、镁（Mg）和磷酸根（PO4）来跟踪反应动力学。对晶种和反应产物进行了化学分析、X射线衍射分析和电子显微镜检查。在通常会自发沉淀无定形磷酸钙（ACP）的条件下，磷灰石减少了游离ACP的形成量，相当一部分最初从溶液中去除的钙和磷酸根直接沉积在晶种上。在足够高的晶种浓度下，所有初始溶液损失都通过后一种途径发生，没有游离ACP沉淀。这些初始事件之后是晶种诱导新的磷灰石晶体形成，同时溶液中的钙和磷酸根进一步减少。对自发形成ACP稳定的过饱和溶液接种磷灰石后，溶液中的钙和磷酸根也发生了类似的减少。这些离子的初始减少是瞬时的，且与晶种浓度成正比。随后离子的去除随时间呈指数下降，并与覆盖在原始晶种上的新磷灰石晶体的形成相关。在使用生理平衡盐溶液的接种实验中，在晶种表面形成的初始沉积物是一种镁稳定的碳酸钙磷酸盐相。这种稳定的表面相并没有阻止磷灰石的二次结晶发生。
