Kangasniemi I M, Vedel E, de Blick-Hogerworst J, Yli-Urpo A U, de Groot K
Biomaterials Research Group, University of Leiden, The Netherlands.
J Biomed Mater Res. 1993 Oct;27(10):1225-33. doi: 10.1002/jbm.820271003.
Calcium phosphate (Ca,P) precipitation behavior on the surface of two bioactive glasses and four bioactive glass composites--two with hydroxylapatite (Ca10(PO4)6 (OH)2) and two with rhenanite (CaNaPO4)--were studied in simulated body fluid (SBF) and in Tris-Buffer at 5, 8, 16, 24, 48, 72, and 144 h. The weight loss of the materials was measured and the amount of precipitation was estimated using scanning electron microscopy with electrochemical detection (SEM-EDX) analysis. The test was repeated for one glass and its respective rhenanite composite every 3 h until 60 h and thereafter every 10 h until 150 h in SBF. Atomic absorption spectroscopy, spectrophotometry, SEM-EDX analysis, and pH measurements were performed on these samples. It is shown that in vitro the composite materials have a higher capacity for Ca,P precipitation than the glasses. Weight losses of the materials correlate well with their composition. Both the glass and Ca,P phases influence the precipitation mechanism and rate. Precipitation begins preferably from the glass phase. Ca,P particles clearly influence the time of onset and rate of precipitation. Cross-sectional EDX analysis of the samples revealed an absence of a clear Si-rich layer in glass A0B0 (SiO2 53.9 mol %, Na2O 27.5, CaO 12.4, P2O5 6.2, Al2O3 0.0 and B2O3 0.0) composites. This was attributed to the presence of extra calcium and phosphate ions on the surface of the material. The ion-concentration and pH change curves offered insight into the mechanism of precipitation. A connection was established between SEM-EDX results and the release curves. Formation of an Si,Ca,Na film was observed that seemed to initiate the Ca,P precipitation.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了两种生物活性玻璃和四种生物活性玻璃复合材料（两种含羟基磷灰石（Ca10(PO4)6(OH)2），两种含磷钠钙石（CaNaPO4））在模拟体液（SBF）和Tris缓冲液中于5、8、16、24、48、72和144小时时的磷酸钙（Ca,P）沉淀行为。测量了材料的重量损失，并使用带有电化学检测的扫描电子显微镜（SEM-EDX）分析估算沉淀量。在SBF中，对一种玻璃及其相应的磷钠钙石复合材料每3小时重复测试一次，直至60小时，此后每10小时重复测试一次，直至150小时。对这些样品进行了原子吸收光谱法、分光光度法、SEM-EDX分析和pH测量。结果表明，在体外，复合材料比玻璃具有更高的Ca,P沉淀能力。材料的重量损失与其组成密切相关。玻璃相和Ca,P相均影响沉淀机制和速率。沉淀优选从玻璃相开始。Ca,P颗粒明显影响沉淀的起始时间和速率。样品的横截面EDX分析显示，在玻璃A0B0（SiO2 53.9摩尔%，Na2O 27.5，CaO 12.4，P2O5 6.2，Al2O3 0.0和B2O3 0.0）复合材料中不存在明显的富硅层。这归因于材料表面存在额外的钙和磷酸根离子。离子浓度和pH变化曲线为沉淀机制提供了见解。建立了SEM-EDX结果与释放曲线之间的联系。观察到形成了一层Si、Ca、Na膜，似乎引发了Ca,P沉淀。（摘要截短至250字）
