THE ROLE OF BRUSHITE AND OCTACALCIUM PHOSPHATE IN APATITE FORMATION
THE ROLE OF BRUSHITE AND OCTACALCIUM PHOSPHATE IN APATITE FORMATION
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DOI：
10.1177/10454411920030010601
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发表时间：
1992-01-01
期刊：
影响因子：
--
通讯作者：
NANCOLLAS, GH
中科院分区：
文献类型：
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作者：
JOHNSSON, MSA;NANCOLLAS, GH
磷灰石矿物形成的研究由于可能形成几个钙磷酸盐相而变得复杂。最难溶解的羟基磷灰石(HAP)优先在中性或碱性条件下形成。在酸性较强的溶液中，经常会发现二水磷酸氢钙(Brushite，DCPD)和磷酸八钙(OCP)等相。即使在理想的HAP沉淀条件下，沉淀物通常也是非化学计量比的，这表明形成了缺钙的磷灰石。DCPD和OCP都被认为可能是磷灰石形成的前驱物质。这可能是由于DCPD和/或OCP的初始沉淀，然后转变为更多的磷脂相。尽管在体外结晶过程中经常检测到DCPD和OCP，但体内的骨形成研究很少显示这些酸性磷酸钙相的存在。在后一种情况下，情况更为复杂，因为存在大量的离子和分子，它们可以结合到晶格中或吸附在微晶表面。在生物磷灰石中，DCPD和OCP通常只有在病理性钙化过程中才能检测到，而病理性钙化往往是pH相对较低的地方。在正常的活体钙化中，没有发现这些相，这表明有其他前体参与，或者形成了初始的无定形磷酸钙相(ACP)，然后转变为磷灰石。
Studies of apatite mineral formation are complicated by the possibility of forming several calcium phosphate phases. The least soluble, hydroxyapatite (HAP), is preferentially formed under neutral or basic conditions. In more acidic solutions phases such as dicalcium phosphate dihydrate (Brushite, DCPD) and octacalcium phosphate (OCP) are often found. Even under ideal HAP precipitation conditions the precipitates are generally nonstoichiometric, suggesting the formation of calcium-deficient apatites. Both DCPD and OCP havea been implicated as possible precursors to the formation of apatite. This may occur by the initial precipitation of DCPD and/or OCP followed by transformation to a more apatitic phase.Although DCPD and OCP are often detected during in vitro crystallization, in vivo studies of bone formation rarely show the presence of these acidic calcium phosphate phases. In the latter case the situation is more complicated, since a large number of ions and molecules are present that can be incorporated into the crystal lattice or adsorbed at the crystallite surfaces. In biological apatite, DCPD and OCP are usually detected only during pathological calcification where the pH is often relatively low. In normal in vivo calcifications these phases have not been found, suggesting the involvement of other precursors or the formation of an initial amorphous calcium phosphate phase (ACP) followed by transformation to apatite.