基于矿化液中胶原聚集行为调控的胶原纤维矿化机理研究

In vitro modeling of collagen mineralization and the biomimetic preparation of bone tissue engineering materials is a hot topic in the field of biomaterials and the self-assembly of collagen in mineralized solutions is the key control procedure. The interactions among collagen, non-collagen proteins (NCPs), polysaccharides and hydroxyapatite (HAP) are both unclear and controversial. Based on the aggregation behavior of collagen in solution, the self-assembly of collagen and the properties of mineralized collagen fibers were correlated with the aggregation structure of collagen in solution, so as to realize the regulations of the collagen mineralization process and the performance of collagen/HAP composites. The project is to study the aggregation structure of collagen in mineralized solution by fluorescence and light scattering etc. Moreover, the self-assembly kinetics of collagen was studied by turbidity method etc. The structure and morphology of HAP were studied by means of energy spectrum and X-ray diffraction etc. The structure and properties of mineralized collagen fibers were studied by means of electron microscopy and thermal analysis etc. The relationship among the aggregation structure of collagen in mineralized solution, collagen self-assembly and the structure and properties of mineralized collagen fibers was elucidated. The regulation mechanism of the NCPs dispersants and polysaccharides on the mineralization of collagen fibers was disclosed. The project has important theoretical significance and application value for the biomimetic preparation of bone tissue engineering materials and the regeneration and repair of bone, and also provides a new experimental basis for biomineralization theory.

体外模拟胶原矿化及仿生制备骨组织工程材料是生物材料领域的研究热点，矿化液中胶原的自组装是关键控制步骤。目前关于胶原、非胶原蛋白（NCPs）、多糖和羟基磷灰石（HAP）之间的相互作用尚不清楚且存在争议。本项目基于胶原在溶液中的聚集行为特点，将胶原自组装、矿化胶原纤维性质与矿化液中胶原的聚集态结构相关联，以此实现对胶原矿化过程以及胶原/HAP复合材料性能的调控。拟采用荧光、光散射等技术研究矿化液中胶原的聚集态结构；采用浊度法等方法研究胶原的自组装动力学；采用能谱、X射线衍射等手段研究HAP的晶体结构形态；采用电镜、热分析等技术研究矿化胶原纤维的结构与性能；阐明矿化液中胶原的聚集态结构、自组装以及矿化胶原纤维结构性能的关系，揭示NCPs分散剂、多糖对胶原纤维矿化的调控机制。本项目研究对于骨组织工程材料的仿生制备以及骨骼的再生与修复都具有重要的理论意义和应用价值，也为生物矿化理论提供新的实验依据。

生物矿化是指生物体在大分子的调控下离子在有机或者无机模板上形成生物矿物的过程。骨作为天然的生物矿物之一，是由矿化胶原纤维组成的具有多层级结构的有机/无机共混物。有机基质是由胶原和非胶原蛋白（NCPs）组成，无机矿物的主要成分是羟基磷灰石（HAP），此外还有硅、镁、锶和钠等微量元素的存在，其中硅已经被证明可以促进成骨细胞的增殖、黏附和分化以及骨的形成和发育。矿化胶原纤维是天然骨的基本结构单元，由胶原和HAP在NCPs的诱导下共同组装而成。通过体外构建仿生胶原矿化体系探究胶原、HAP和NCPs三者之间的相互作用，对于理解生物体内的真实矿化机制、研发组成和结构高度仿生的骨修复材料都具有重要的研究价值。. 项目按计划执行完成了申报书中的所有研究内容。基于NCPs富含谷氨酸、天冬氨酸等序列的特征，本项目首先从胶原自组装行为的角度出发，考察胶原自组装各阶段的聚集状态与矿化胶原材料结构性能的关系；进而引入氨基酸/多肽类的NCPs模拟物同步调控胶原自组装行为和HAP形成过程，制备获得结构与性能可控的矿化胶原材料，并从分子水平上分析了NCPs模拟物与胶原、羟基磷灰石/前驱体之间的相互作用，引入多巴胺对矿化胶原材料进行理化和细胞黏附性能的改进。选用硅酸钠作为硅源，研究硅酸钠对于胶原聚集态结构和自组装行为的关系，进一步将硅引入生物矿化系统中结合纤维内矿化制备掺硅复合矿化胶原材料。本项目研究为深入理解生物矿化机制以及仿生构建胶原基矿化材料提供了理论依据，为设计和制备组成和结构接近天然骨的仿生骨矿物材料提供了理论指导。.在本项目执行期间，共发表学术论文19篇，其中SCI收录论文14篇，北大中文核心期刊4篇，其它杂志1篇，参加国际学术会议墙报展示论文2篇，授权中国发明专利10项。此外，培养博士研究生毕业4人，硕士研究生毕业11人。