Liu Changsheng, Chen Chien-Wen, Ducheyne Paul
Key Laboratory for Ultrafine Materials of Ministry of Education, Engineering Research Center for Biomedical Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
Biomed Mater. 2008 Sep;3(3):034111. doi: 10.1088/1748-6041/3/3/034111. Epub 2008 Aug 8.
Composites of hydrated calcium phosphate cement (CPC) and bioactive glass (BG) containing Si were immersed in vitro to study the effect of chemical composition on surface reaction layer formation and dissolution/precipitation behavior. The solutions used were 0.05 M tris hydroxymethyl aminomethane/HCl (tris buffer), tris buffer supplemented with plasma electrolyte (TE) with pH 7.4 at 37 degrees C, and this solution complemented with 10% newborn bovine serum (TES). The post-immersion solutions were analyzed for changes in Ca, PO(4) and Si concentrations. The reacted surfaces were analyzed using Fourier transform infrared (FTIR), and scanning electron microscopy with energy dispersive x-ray analysis. The sample weight variations after immersion were also determined. The results showed that the composition of the bioactive composite CPCs greatly affected their behavior in solution and the formation of apatite bioactive surface reaction layers. After immersion in the TE solution, Ca ions were taken up by all samples during the entire immersion duration. Initially, the P ion concentration increased sharply, and then decreased. This reaction pattern reveals the formation of an amorphous calcium phosphate layer on the surface of these composite CPCs. FTIR revealed that the layer was, in fact, poorly crystallized Ca-deficient carbonate apatite. The thickness of the layer was 12-14 microm and it was composed of rod-like apatite with directional arrangement. For immersion in the TES solution, the Ca and Si ion concentrations showed a similar behavior to that in TE, but the release rate of Si ions was higher. FTIR revealed that after TES immersion, not only did the typical, poorly crystallized, Ca-deficient carbonated apatite form, as it did in TE, but also the serum proteins co-adsorbed on the surface and thereby affected the surface reaction layer formation. A thinner apatite layer was formed and was composed of a micro-porous layer comprising rounded particles in a glue-like matrix. The addition of BG to the CPCs to create composite CPCs obviously is at the basis of this altered behavior of the cements. All data combined are useful for the design and optimization of degradable implant materials for use in bone tissue repair and regeneration procedures.
将含有硅的水合磷酸钙骨水泥（CPC）与生物活性玻璃（BG）的复合材料进行体外浸泡，以研究化学成分对表面反应层形成及溶解/沉淀行为的影响。所用溶液为0.05M三羟甲基氨基甲烷/盐酸（tris缓冲液）、补充了血浆电解质（TE）且pH值为7.4、温度为37℃ 的tris缓冲液，以及添加了10%新生牛血清的该溶液（TES）。对浸泡后的溶液进行钙、磷酸根和硅浓度变化的分析。使用傅里叶变换红外光谱（FTIR）以及带有能量色散X射线分析的扫描电子显微镜对反应后的表面进行分析。还测定了浸泡后样品的重量变化。结果表明，生物活性复合CPC的组成极大地影响了它们在溶液中的行为以及磷灰石生物活性表面反应层的形成。浸泡在TE溶液中后，在整个浸泡期间所有样品都吸收了钙离子。最初，磷酸根离子浓度急剧上升，随后下降。这种反应模式表明在这些复合CPC表面形成了无定形磷酸钙层。FTIR显示该层实际上是结晶度较差且缺钙的碳酸磷灰石。该层厚度为12 - 14微米，由呈定向排列的棒状磷灰石组成。对于浸泡在TES溶液中的情况，钙和硅离子浓度表现出与在TE溶液中相似的行为，但硅离子的释放速率更高。FTIR显示，浸泡在TES溶液后，不仅像在TE溶液中那样形成了典型的、结晶度较差且缺钙的碳酸磷灰石，而且血清蛋白共吸附在表面，从而影响了表面反应层的形成。形成了较薄的磷灰石层，其由在胶状基质中包含圆形颗粒的微孔层组成。向CPC中添加BG以制备复合CPC显然是导致这些骨水泥行为改变的基础。所有综合数据对于设计和优化用于骨组织修复和再生过程的可降解植入材料是有用的。
