Fourier transform infrared spectroscopy of the solution-mediated conversion of amorphous calcium phosphate to hydroxyapatite: New correlations between X-ray diffraction and infrared data
Fourier transform infrared spectroscopy of the solution-mediated conversion of amorphous calcium phosphate to hydroxyapatite: New correlations between X-ray diffraction and infrared data
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DOI：
10.1007/bf02509540
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发表时间：
1996-01-01
影响因子：
4.2
通讯作者：
Boskey, AL
中科院分区：
文献类型：
--
作者：
Gadaleta, SJ;Paschalis, EP;Boskey, AL
对在恒定pH或可变pH下由无定形磷酸钙（ACP）转化形成的成熟的、结晶不良的羟基磷灰石（HA）的傅立叶变换红外光谱分析显示，在nu（1）、nu（3）磷酸盐吸收区域（900 cm（-1）-1200 cm（-1））中仅发生细微变化。该区域是感兴趣的，因为它可以通过使用FT-IR显微镜分析矿化组织切片来检测。为了评估在成熟过程中发生的细微光谱变化，计算光谱的二阶导数。在恒定pH下形成的HA在二阶导数峰位置显示出很小或没有变化，其中条带出现在960 cm（-1）、985 cm（-1）、1030 cm（-1）、1055 cm（-1）、1075 cm（-1）、1096 cm（-1）、1116 cm（-1）和1145 cm（-1）处。这些频带可以被分配到HA的磷灰石/化学计量环境中的磷酸盐（PO 43-）部分的分子振动。相反，在可变pH下形成的HA成熟的早期阶段，在958 cm（-1）、985 cm（-1）、1020 cm（-1）、1038 cm（-1）、1112 cm（-1）和1127 cm（-1）处出现的二阶导数峰位置随着成熟而移动，表明磷酸盐物质的环境随着晶体成熟而变化。在1020 cm（-1）、1038 cm（-1）、1112 cm（-1）和1127 cm（-1）处的峰归因于非化学计量和/或含酸性磷酸盐物质的存在。通过对在可变pH下制备的合成材料进行化学分析测得的较低Ca：P摩尔比支持这一概念。使用二阶导数峰位置作为初始输入参数，对在恒定pH下制备的合成HA的nu（1）、nu（3）磷酸盐区域进行曲线拟合。还对这些相同材料的X射线衍射图案进行曲线拟合，以计算c轴002反射以及102、210、211、112、300、202和301平面中的堆积类型（尺寸/完美度）的变化。线性回归分析表明，在982 cm（-1）、999 cm（-1）、1030 cm（-1）、1075 cm（-1）、1096 cm（-1）、1116 cm（-1）和1145 cm（-1）处的底层谱带的面积百分比变化与一个或多个反射平面中的结晶度变化相关。有人建议，结合二阶导数和曲线拟合分析的nu（1），nu（3）磷酸轮廓允许这些光谱的最可重复的评价。
Fourier Transform infrared spectroscopic analysis of maturing, poorly crystalline hydroxyapatite (HA) formed from the conversion of amorphous calcium phosphate (ACP) at constant pH or variable pH show only subtle changes in the nu(1), nu(3) phosphate absorption region (900 cm(-1)-1200 cm(-1)). This region is of interest because it can be detected by analysis of mineralized tissue sections using FT-IR microscopy. To evaluate the subtle spectral changes occurring during the maturation, second derivatives of the spectra were calculated. HA formed at constant pH showed little or no variation in the second derivative peak positions with bands occurring at 960 cm(-1), 985 cm(-1), 1030 cm(-1) 1055 cm(-1), 1075 cm(-1), 1096 cm(-1), 1116 cm(-1), and 1145 cm(-1). These bands can be assigned to molecular vibrations of the phosphate (PO43-) moiety in an apatitic/stoichiometric environment of HA. In contrast, during the early stages of maturation of the HA formed at variable pH, second derivative peak positions occurring at 958 cm(-1), 985 cm(-1), 1020 cm(-1), 1038 cm(-1), 1112 cm(-1), and 1127 cm(-1) shifted in position with maturation, indicating that the environment of the phosphate species is changing as the crystals mature. Peaks at 1020 cm(-1) 1038 cm(-1), 1112 cm(-1), and 1127 cm(-1) were attributable to nonstoichiometry and/or the presence of acid phosphate-containing species. This concept was supported by the lower Ca:P molar ratios measured by chemical analysis of the synthetic material made at variable pH. Using the second derivative peak positions as initial input parameters, the nu(1), nu(3) phosphate region of the synthetic HAs prepared at constant pH were curve fit. X-ray diffraction patterns of these same materials were also curve fit to calculate the changes in crystallinty (size/perfection) in the c-axis 002 reflection as well as the 102, 210, 211, 112, 300, 202, and 301 planes. Linear regression analysis showed that the changes in the percent area of the underlying bands at 982 cm(-1), 999 cm(-1), 1030 cm(-1), 1075 cm(-1), 1096 cm(-1) 1116 cm(-1), and 1145 cm(-1) were correlated with changes in crystallinity in one or more of the reflection planes. It is suggested that a combination of second-derivative and curve-fitting analysis of the nu(1), nu(3) phosphate contour allows the most reproducible evaluation of these spectra.