Gupta Gautam, Kirakodu Sreenatha, El-Ghannam Ahmed
Center for Biomedical Engineering, Graduate School, University of Kentucky, Lexington, Kentucky 40506, USA.
J Biomed Mater Res A. 2007 Feb;80(2):486-96. doi: 10.1002/jbm.a.31005.
Silica-calcium phosphate nanocomposite (SCPC) has recently been proposed as a novel resorbable, bioactive, and mechanically compatible template for bone reconstruction. The effect of the physicochemical properties on the surface reactivity and dissolution kinetics of SCPC immersed in simulated body fluid (SBF) was investigated and compared to that of bioactive glass (BG). Moreover, the stimulatory effect on osteoblast gene expression of SCPC was determined using quantitative real-time polymerase chain reaction (qRT-PCR), and compared to that of hydroxyapatite (HA-200). Mercury porosimetry revealed that surface areas of SCPC particles containing 10 (SCPC10), 30 (SCPC30), and 50 (SCPC50) wt % Si-content were 14-, 18-, and 32-times higher than that of BG. Inductively coupled plasma analysis showed that after 192 h of immersion, Si-rich SCPC50 exhibited controlled bulk-dissolution and released 43.1 ppm Si, which was sixfold higher than that released from BG (7.7 ppm). Moreover, SCPC50 showed a rapid Ca-uptake from SBF and developed a surface apatite layer after only 2 h, whereas a similar layer was detected on BG after 8 days of immersion under the same experimental conditions. qRT-PCR revealed that osteopontin and osteocalcin mRNA expression by osteoblast-like cells attached to Si-rich SCPC50 was significantly higher than that on HA-200 or polystyrene after 2 days in culture. This suggested a role of dissolved Si in stimulating the differentiation and mineralization of osteoblast precursor cells. The favorable physiochemical and bioactivity properties of Si-rich SCPC nanocomposite indicate that SCPC can have wide applications as a synthetic bone graft for cell delivery applications in tissue engineering.
硅-磷酸钙纳米复合材料（SCPC）最近被提议作为一种用于骨重建的新型可吸收、生物活性且机械性能兼容的模板。研究了其物理化学性质对浸入模拟体液（SBF）中的SCPC表面反应性和溶解动力学的影响，并与生物活性玻璃（BG）进行了比较。此外，使用定量实时聚合酶链反应（qRT-PCR）测定了SCPC对成骨细胞基因表达的刺激作用，并与羟基磷灰石（HA-200）进行了比较。压汞法显示，含10（SCPC10）、30（SCPC30）和50（SCPC50）重量百分比硅含量的SCPC颗粒的表面积分别比BG高14倍、18倍和32倍。电感耦合等离子体分析表明，浸泡192小时后，富含硅的SCPC50表现出可控的整体溶解，并释放出43.1 ppm的硅，这比从BG释放的硅（7.7 ppm）高六倍。此外，SCPC50在仅2小时后就显示出从SBF中快速摄取钙并形成表面磷灰石层，而在相同实验条件下浸泡8天后在BG上才检测到类似的层。qRT-PCR显示，培养2天后，附着在富含硅的SCPC50上的成骨样细胞中骨桥蛋白和骨钙素mRNA的表达明显高于HA-200或聚苯乙烯上的表达。这表明溶解的硅在刺激成骨细胞前体细胞的分化和矿化中起作用。富含硅的SCPC纳米复合材料良好的物理化学和生物活性特性表明，SCPC作为组织工程中用于细胞递送应用的合成骨移植材料具有广泛的应用前景。
