【作者】 赵娜如；

【导师】 王迎军；

【作者基本信息】 华南理工大学 ， 材料学， 2011， 博士

【摘要】 天然的生物体能够在生物大分子的精确调控下,通过生物矿化过程合成具有特殊形貌和功能的生物矿物。目前,仿生合成各种形貌、尺寸和多级结构的无机材料和有机-无机复合材料引起了材料学家的普遍关注。本研究采用模板技术和仿生技术制备不同形貌的生物活性玻璃微纳米粉体,结合粉体表面修饰技术,提高无机粉体与有机基相的界面亲和性,制备具有三维多孔结构的生物活性骨修复材料。利用XRD、SEM/EDX、FTIR、BET、DSC/TG等各种材料结构、性能分析方法和体外模拟实验方法对溶胶-凝胶生物活性微纳米粉体及其壳聚糖/生物活性玻璃复合多孔材料的显微结构、生物活性和矿化特性进行了深入研究,探讨了生物活性玻璃微纳米粉体的合成机理。本研究提出采用模板仿生合成技术结合溶胶-凝胶技术来控制生物活性玻璃的颗粒大小、尺寸及多级结构,实现了多种形貌生物活性玻璃的模板仿生合成。采用体外模拟矿化实验研究了材料的体外矿化性能及生物活性。探讨了制备工艺参数对生物玻璃粉体颗粒大小、形貌及比表面积、孔容等物理性质的控制规律及几种生物活性玻璃微纳米粉体的合成机理。研究表明:(1)在溶胶-凝胶工艺中引入聚乙二醇(PEG)作为分散剂可以调控生物活性玻璃颗粒的分散状态和形貌,控制PEG的加入量是能否达到最好分散效果的关键。采用该技术可以调控生物活性玻璃的粒度大小、比表面积及钙磷离子释放情况。PEG与生物活性玻璃凝胶粒子的作用机理为空间位阻稳定机理;(2)通过模板法结合溶胶-凝胶法成功制备了生物活性玻璃纳米纤维簇,宽度范围在50~120nm,长度范围约为200~500nm,并且纳米纤维簇是由规则排列的纳米纤维堆积形成,纳米纤维宽度约为10nm,其形成机理是由于模板剂吐温-80在溶胶液中形成棒状胶束结构,通过羟基化作用和亲水基团引导调控纳米纤维簇的生成。(3)采用碱性催化剂氨水及十二胺催化制备了不同尺寸的生物活性玻璃微球及多孔微球,探讨了加料方式,反应温度,原料配比等工艺条件对生物活性玻璃粉体的颗粒形貌和粒径大小的影响规律,其中十二胺具有催化剂和模板剂的双重作用,在反应体系中形成蠕虫状胶束,胶束表面的亲水基团与生物活性玻璃的前驱物以氢键作用结合,经高温处理后在生物活性玻璃微纳米球内部成孔。(4)体外模拟矿化实验结果表明,本研究制备的生物活性玻璃微米球、纳米纤维簇和纳米球具有良好的生物矿化性能,证明所制备的不同形貌和大小的生物活性玻璃都具有优良的生物活性。采用生物大分子卵磷脂对生物玻璃粉体进行表面改性,并研究了生物活性玻璃与卵磷脂的相互作用。表面改性后生物玻璃粉体在壳聚糖有机基相中均匀分散,在一定程度上提高界面的相容性。采用冷冻干燥法制备了壳聚糖/溶胶凝胶生物活性玻璃仿生型复合多孔支架,探讨了生物玻璃粉体的表面改性及各组分不同用量对壳聚糖/溶胶凝胶生物活性玻璃复合支架显微结构及压缩强度的影响,并对其微观结构、孔隙率、压缩强度、体外矿化等性能进行了研究。研究结果表明:所制备的复合支架材料的孔径尺寸分布均匀,具有高度连通的孔隙结构,孔径大小在50~200μm之间,其气孔率在90%以上。改性后生物玻璃粉体与壳聚糖复合材料的压缩强度比改性前明显提高。更多还原

【Abstract】 In nature, biological systems are able to generate specifically functionalized crystalline materials with complex morphologies via the process of biomineralization that is delicately controlled by certain biomarcromolecules. Recently, controlled synthesis of inorganic and inorganic/organic hybrid materials of specific morphology, different particle size and hierarchical structure have drawn signifcant attention to the community of material sciences. In this study, bioactive glass micro-nanoscale particles with different shapes were synthesed by organic template method. The surface of micro-nanoscale particles were modified to improve the interfacial interaction between organic matrix and inorganic particles. Bone repairing materials with three dimensional porous structures were obtained with good mechanical strength. The nano-structure, bioactivity and bio-mineralization characteristics of the sol-gel derived bioactive glass and chitosan/bioactive glass (CS/BG) composite materials were investigated in detail by using XRD, SEM/EDX, FTIR, BET and DSC/TG techniques, as well as in vitro methods. The synthetic mechanism of the bioactive glass micro-nanoscale particles was also discussed.In this work, the combination of sol-gel and biomimetic organic template technologies were used to prepare micro-sized and nano-sized bioactive glass particles with different shapes and hierarchical structure. In vitro test was used to characterize the biomineralization and bioactive properties of these materials. The effects of fabrication parameters on the properties of final products, including particle size, shape, specific surface area and pore volume were studied while the shape control mechanism of bioactive glass particles was discussed. The results indicated that: (1)The dispersive state and microstructure of bioactive glass could be controlled by sol-gel technology by adding PEG as dispersant, the dispersive effect of bioactive glass was influenced by the content of PEG. Particle size, surface area and ions release behavior could be controlled and the dispersive mechanism could be explained by steric hindrance stabilization theory. PEG could adhere to the surface of bioglass particles to eliminate the interaction among particles. (2)The nano-fiber clusters of bioactive glass were successfully synthesized using sol-gel and tween-80 surfactant templating methods. These nano-fiber clusters, approximately 50~120nm in width and 200~500nm in length, were accumulated by well-ordered nano-fibers of 10nm in width. Tween-80 template in sol solution could form rod shape micelle structure, and the main driving forces for nano-clusters formation were hydroxylation reaction and hydrophilic effect. ( 3 ) Bioactive glass micro-spheres and porous micro-spheres were synthesized using ammonia and dodecylamine as catalyzer while water and ethanol were used as solvent. Technical parameters such as the speed of sample addition, reaction temperature and the ratio of starting materials, etc, were studied. In addition to catalysis, dodecylamine could also served as organic template to trigger the formation of wormlike micelle in our reaction system. The precursor of bioactive glass was reacted with micelle by hydrogen bonding and porous stucture was formed after high temperature treatment. ( 4 ) The results of in vitro test demonstrated outstanding biominerilization properties among the bioglass micro-spheres, nano-fiber clusters and nano-spheres. It further suggested that bioglass of different shapes and particle sizes exhibited great in vitro bioactivity.Bioactive glass powders were treated with phosphatidyl cholines, and the interactions between bioactive glass and phosphatidyl cholines were studied. Surface modification of bioactive glass (MBG) particles improved the interfacial interaction between bioactive glass particles and chitosan matrix, such that a uniform distribution of modified bioactive glass particles in the chitosan matrix was observed. A biomimetic porous composite was prepared from chitosan and sol-gel bioactive glass powders by freeze-drying technique. The effects of surface and component modification on the microscopic features and the compressive strength of bioactive glass were studied. The microstructure, porosity, compressvie strength and bio-mineralization characteristics of the chitosan/bioactive glass (CS/BG) composite materials were also investigated. The results suggested that the composite scaffolds were featured with highly interconnected pores with pore size ranging from 50~200μm and the overall porosity of the scaffolds was above 90%. The compressive strength of the composite could be improved by surface modification of bioactive glass.更多还原