氧化石墨烯/壳聚糖/羟基磷灰石载药复合支架的制备及骨诱导机理研究

The carboxylic graphene-oxide(GO)/chitosan(CS)/hydroxylapatite(HA) composites were prepared by using the high specific surface area and good cell viability of graphene oxide. Bone morphogenetic protein-2 (BMP-2) molecules were loaded through the electrostatic interactions between the functional groups on the composites and the BMP-2. The strength of the composite was improved by the EDC reaction of carboxylic GO and CS. In this proposal, the main research contents includes: (1) the preparation of the graphene oxide and its modification, the preparation of the GO/CS/HA composites; (2) comparing the difference of the composites prepared by the weak interactions and the EDC reactions by computer simulation and characterization methods; (3) loading BMP-2 to the composites surface by heparin molecules, study the drug loading, release behavior and their effects on the stem cell differentiation. The key innovations is that the strength of the composites could be improved by EDC reactions which would give guarantee for the playing of outstanding properties of GO. Experimental and theoretical studies on the regulating of the macro-properties of the materials by their micro-interfacial interactions would provide a good thinking in the design of the scaffolds.

本申请拟利用氧化石墨烯(GO)高比表面积、良好的细胞活性等，制备羧基功能化GO/壳聚糖(CS)/羟基磷灰石(HA)复合支架。通过支架表面活性基团-生物大分子间的静电作用携载骨形态发生蛋白(BMP-2)。通过羧基化GO与CS的EDC催化反应，提高其力学性能。同时利用GO的高比表面积为携载BMP-2提供位点。主要研究内容：(1) GO制备及羧基化， GO/CS/HA三元支架制备，优化各组分含量。(2) 通过计算机模拟和实验研究比较次级键(如氢键、静电等)作用和EDC化学键作用对支架宏观性能的调控作用。(3)利用肝素与BMP-2的静电作用携载因子，研究载药量，释放行为及其与对干细胞分化行为的影响。其创新点是：通过EDC催化反应有效提高材料界面作用，为发挥GO的优良性能提供保障。实验结合计算机模拟研究材料微观界面相互作用模式调控宏观性能的研究方法，为设计定制支架材料提供有益的参考。

本项目主要研究了氧化石墨烯/壳聚糖复合骨诱导支架材料中氧化石墨烯/壳聚糖间的相互作用，通过实验表征（XPS及红外分析）及理论模拟（反应力场分子动力学计算）证实二者间为非化学键合，从原理上说明了为什么单纯共混制备的复合材料支架力学性能不够。进而通过羧基、氨基EDC反应成功制备了具有界面化学键合的氧化石墨烯/壳聚糖复合材料，通过在材料中负载骨诱导因子及纳米羟基磷灰石得到了具有较好骨诱导性能的复合支架材料。本研究的开展为制备具有特定界面相互作用的氧化石墨烯/壳聚糖复合材料提供了有益参考，为推动该复合支架材料的临床应用提供了基础。