Gou Zhongru, Weng Wenjian, Du Piyi, Han Gaorong, Yan Weiqi
Department of Materials Science and Engineering, Zhejiang University, Zheda Road 37, Hangzhou 310027, China.
J Biomed Mater Res A. 2008 Jun 15;85(4):909-18. doi: 10.1002/jbm.a.31582.
The biomaterials that can control the active ions delivery to enhance cell activity are regarded as promising bone regenerative materials. In this study, a new approach aiming to layer-by-layer (LbL) assemble the bioavailable zinc ions in the core-shell-like silica@octacalcium phosphate (OCP) nanosphere and to analyze its efficacy on improving controlled-release was reported. Firstly, a pH-responsive electrostatic interaction was used to adsorb zinc ions on silica nanospheres with different zinc concentration, which was followed by coating silica gel layer. Then the nanospheres were LbL assembled with zinc ions and silica gel alternately until the desired multilayered nanospheres were achieved. Finally, the porous OCP shells were capped onto the outside surface of the nanospheres tailored by poly(aspartic acid) sodium molecules. The ion release tests in Tris buffers in vitro indicated that zinc release was controlled by pH and storage capacity, and silicon release was regulated by the OCP shell barrier. A temporal gradient within short times and sustained-dosage for a prolonged time toward the zinc and silicon ions could be obtained in this multilayer system. The results of this organized active ion assembly might open a promising future direction for effective delivery of trace elements in bone defect therapy.
能够控制活性离子递送以增强细胞活性的生物材料被视为有前景的骨再生材料。在本研究中，报道了一种旨在逐层（LbL）组装核壳状二氧化硅@磷酸八钙（OCP）纳米球中生物可利用锌离子并分析其对改善控释效果的新方法。首先，利用pH响应性静电相互作用将不同锌浓度的锌离子吸附在二氧化硅纳米球上，随后包覆硅胶层。然后将纳米球与锌离子和硅胶交替进行LbL组装，直至获得所需的多层纳米球。最后，将多孔OCP壳覆盖在由聚天冬氨酸钠分子定制的纳米球外表面。体外Tris缓冲液中的离子释放测试表明，锌释放受pH值和储存容量控制，硅释放受OCP壳屏障调节。在该多层系统中，短时间内可获得锌离子和硅离子的时间梯度，长时间内可实现持续给药。这种有组织的活性离子组装结果可能为骨缺损治疗中微量元素的有效递送开辟一个有前景的未来方向。
