Nanocrystals of magnesium and fluoride substituted hydroxyapatite
Nanocrystals of magnesium and fluoride substituted hydroxyapatite
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DOI：
10.1016/s0162-0134(98)10058-2
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发表时间：
1998-10-01
影响因子：
3.9
通讯作者：
Roveri, N
中科院分区：
文献类型：
--
作者：
Bertoni, E;Bigi, A;Roveri, N
在溶液I、5和10at.%中加入不同浓度的镁离子和氟离子合成了羟基磷灰石纳米晶，并对其进行了结构和化学表征。这些合成是在低分子量聚丙烯酸的存在下进行的，低分子聚丙烯酸已被证明能抑制羟基磷灰石的结晶。聚电解质在合成过程中被吸附到晶体中，并导致平均晶体尺寸减小。沿与c轴垂直的方向还原程度较大，表明聚电解质优先吸附在平行于c轴的晶面上。镁和氟化物都可以被结合到羟基磷灰石结构中。根据晶格常数和固相中镁的相对含量，可以认为可能只有一部分镁被钙取代，其余的被吸附在晶体表面。然而，镁破坏了磷灰石结构的稳定性，有利于其热转化为p-磷酸三钙，并对羟基磷灰石的结晶表现出抑制作用。聚丙烯酸的同时存在增强了最后一种效应。氟离子取代羟基磷灰石结构后，晶体尺寸沿c轴方向略有增大。实验结果表明，该实验方法可以成功地制备出结晶度、晶体尺寸、组成、结构和稳定性与生物磷灰石非常接近的纳米磷灰石。(C)1998 Elsevier Science Inc.保留所有权利。
Hydroxyapatite nanocrystals synthetized in the presence of different concentrations of magnesium and fluoride ions in solutions I, 5 and 10 at.% have been submitted to a structural and chemical characterization. The syntheses were carried out in the presence of low molecular weight polyacrilic acid, which has been verified to inhibit hydroxyapatite crystallization. The polyelectrolyte is adsorbed into the crystals during the synthesis and provokes a reduction of the mean crystal sizes. The reduction is greater along the direction orthogonal to the c-axis, suggesting a preferential adsorption of the polyelectrolyte on the crystalline faces parallel to the c-axis. Both magnesium and fluoride can be incorporated into the hydroxyapatite structure. On the basis of the values of the lattice constants and of the magnesium relative content of the solid phase, it can be suggested that probably just a part of magnesium is substituted for calcium, the remainder being adsorbed on the crystal surface. However, magnesium destabilizes the apatitic structure favouring its thermal conversion into p-tricalcium phosphate, and displays an inhibiting effect on the crystallization of hydroxyapatite. This last effect is enhanced by the simultaneous presence of polyacrylic acid. Fluoride substitution for hydroxyl ions into hydroxyapatite structure induces a slight increase of the crystal sizes along the c-axis direction. The data indicate that the experimental approach can be successfully used to prepare nanoapatite with crystallinity, crystal dimensions, composition, structure and stability very close to those characteristic of biological apatites. (C) 1998 Elsevier Science Inc. All rights reserved.