利用硅灰石(CaSiO3)和β-磷酸三钙(β-TCP)在骨损伤环境中降解速率存在显著性差异的基本特性，以海藻多糖凝胶球为模板，运用层-层包裹方法构建CaSiO3、β-TCP交替包裹的多壳层化中空微球。首先，将海藻酸钠与硅酸钠的混合水溶胶逐滴加入到温和搅拌的硝酸钙水溶液中，形成由水合硅酸钙盐为壳层的海藻多糖基复合微球，然后将该复合微球依次浸入到含β-TCP的海藻酸钠溶液和含CaSiO3的海藻酸钠溶液中，温和搅拌后将微球悬浮液分离，再经真空冷冻干燥和850℃煅烧处理，从而获得以CaSiO3为最内壳层并具有双壳层或三壳层的中空微球。按类似步骤也可以制备以β-TCP为最内壳层的多壳层中空微球。运用SEM、EDX、XRD和FTIR对该类微球的微结构和组成进行了分析。运用弱酸性Tris缓冲液(pH=5.2)对双壳层中空微球的降解。实验证明，缓冲液中硅、磷浓度变化特征与其外壳层、内壳层化学组成(即β-TCP或 CaSiO3)密切相关。本研究结果对构建降解速率阶段可调的复合陶瓷多孔生物材料以及研究原位骨再生效率与孔道网络演化规律之间关系等具有重要学术价值。
A series of hollow bioceramic microspheres with two or three shell layers were fabricated via alginate microsphere template and layer-by-layer coating techniques. The Na2SiO3-alginate mixture hydrosol beads were firstly injected into the Ca(NO3)2 aqueous solution under mild stirring to form calcium silicate hydrate-coated algi-nate microspheres. The composite microspheres were dispersed into the beta-tricalcium phosphate (β-TCP)-containing alginate hydrosol and wollastonite (CaSiO3)-containing alginate hydrosol in turn while gently stirring. The microspheres were filtered, dried in vacuum and finally calcined at 850℃ for 2 h to obtain the multi-shell hol-low bi-phase ceramic microspheres. The microstructure and chemical composition of the microspheres were char-acterized by SEM, EDX, XRD and FTIR analysis. In vitro biodegradation behavior of the two-shell hollow micro-spheres was tested in weak acidic Tris buffer and confirmed a unique controlled release characteristic for the silicate and phosphate groups. These results suggest that the rational design of the two- or multi-shell layer allows the preparation of bioceramic composites composed of β-TCP and CaSiO3 with stage adjustable biodegradation and these biomaterials are potential candidates for improving bone regeneration and repair.
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