Rey C, Shimizu M, Collins B, Glimcher M J
Laboratory for the Study of Skeletal Disorders and Rehabilitation, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
Calcif Tissue Int. 1990 Jun;46(6):384-94. doi: 10.1007/BF02554969.
In order to investigate the possible existence in biological and poorly crystalline synthetic apatites of local atomic organizations different from that of apatite, resolution-enhanced, Fourier transform infrared spectroscopy studies were carried out on chicken bone, pig enamel, and poorly crystalline synthetic apatites containing carbonate and HPO4(2-) groups. The spectra obtained were compared to those of synthetic well crystallized apatites (stoichiometric hydroxyapatite, HPO4(2-)-containing apatite, type B carbonate apatite) and nonapatitic calcium phosphates which have been suggested as precursors of the apatitic phase [octacalcium phosphate (OCP), brushite, and beta tricalcium phosphate and whitlockite]. The spectra of bone and enamel, as well as poorly crystalline, synthetic apatite in the upsilon 4 PO4 domain, exhibit, in addition to the three apatitic bands, three absorption bands that were shown to be independent of the organic matrix. Two low-wave number bands at 520-530 and 540-550 cm-1 are assigned to HPO4(2-). Reference to known calcium phosphates shows that bands in this domain also exist in HPO4(2-)-containing apatite, brushite, and OCP. However, the lack of specific absorption bands prevents a clear identification of these HPO4(2-) environments. The third absorption band (610-615 cm-1) is not related to HPO4(2-) or OH- ions. It appears to be due to a labile PO4(3-) environment which could not be identified with any phosphate environment existing in our reference samples, and thus seems specific of poorly crystalline apatites. Correlation of the variations in band intensities show that 610-615 cm-1 band is related to an absorption band at 560 cm-1 superimposed on an apatite band. All the nonapatitic phosphate environments were shown to decrease during aging of enamel, bone, and synthetic apatites. Moreover, EDTA etching show that the labile PO4(3-) environment exhibited a heterogeneous distribution in the insoluble precipitate.
为了研究生物磷灰石和结晶性差的合成磷灰石中可能存在的不同于磷灰石的局部原子结构，利用分辨率增强的傅里叶变换红外光谱对鸡骨、猪牙釉质以及含有碳酸根和HPO4(2-)基团的结晶性差的合成磷灰石进行了研究。将所得光谱与合成的结晶良好的磷灰石（化学计量比的羟基磷灰石、含HPO4(2-)的磷灰石、B型碳酸磷灰石）以及被认为是磷灰石相前驱体的非磷灰石磷酸钙（八钙磷酸钙（OCP）、透钙磷石和β-磷酸三钙及白磷钙矿）的光谱进行了比较。骨和牙釉质以及结晶性差的合成磷灰石在υ4 PO4区域的光谱，除了三条磷灰石谱带外，还显示出三条与有机基质无关的吸收谱带。520 - 530和540 - 550 cm-1处的两条低波数谱带归属于HPO4(2-)。参考已知的磷酸钙表明，该区域的谱带在含HPO4(2-)的磷灰石、透钙磷石和OCP中也存在。然而，缺乏特定的吸收谱带使得无法明确识别这些HPO4(2-)环境。第三条吸收谱带（610 - 615 cm-1）与HPO4(2-)或OH-离子无关。它似乎是由于一种不稳定的PO4(3-)环境导致的，这种环境无法与我们参考样品中存在的任何磷酸盐环境相识别，因此似乎是结晶性差的磷灰石所特有的。谱带强度变化的相关性表明，610 - 615 cm-1谱带与叠加在磷灰石谱带上的560 cm-1处的吸收谱带相关。所有非磷灰石磷酸盐环境在牙釉质、骨和合成磷灰石老化过程中均减少。此外，EDTA蚀刻表明，不稳定的PO4(3-)环境在不溶性沉淀中呈现出不均匀分布。
