石墨烯/生物玻璃多孔支架的蛋白质发泡法制备与性能研究

Bioactive glasses have been used in a range of biomedical applications such as non-load-bearing implants, bioactive coatings, bone cements and tissue engineering scaffolds due to excellent osteoconductivity and bioactivity. On approach to resolve the problem of the mechanical weakness and brittleness of bioactive glasses, the purpose of this project is to present a graphene reinforced bioactive glasses porous scaffold using the environmentally-friendly protein foaming technique. The green porous scaffold is based on the protein foaming, where the foam is stabilised with interconnected egg white protein, and then the graphene and bioactive glasses particles are added in to attach on the foam surface. After drying and sintering without air, the porous graphene/bioactive glasses scaffold is obtained. One of the key researches is to investigate the denaturation of egg white protein to form stabilised liquid foam, which provides the uniformly distributed and controllable porous microstructure. Based on this microstructure, mechanical properties of the porous scaffold can be improved. Another key research is focus on the bioactive glasses reinforcement based on the interfacial composition of graphenes. Graphene is a two-dimensional carbon-based nanostructure, with relatively similar mechanical properties to those of carbon nanotubes (CNTs), Graphene is not only applied as a reinforcement in composites as CNTs, but also overcome the dispersancy problems normally involved with CNTs. This project has an innovative way to improve the mechanical performance of porous bioactive glasses scaffold, with integration of the porous microstructure control using protein foaming technique and composite reinforcement with graphenes. Furthermore, this project will expand the biomedical research on grahenens, and development the load-bearing applications for porous bioactive glasses scaffold.

由于良好的生物活性，生物玻璃作为骨组织工程支架的应用越来越广泛，但是陶瓷的天然脆性限制了生物玻璃在多孔骨组织工程支架上的应用。为了提高生物玻璃的机械性能，本项目提出一种利用环境友好的蛋白质发泡法可控制备石墨烯增强生物玻璃多孔支架的新方法：利用蛋清蛋白质互相缠绕稳定泡沫的气液两相界面，添加石墨烯与生物玻璃附着在稳定的泡沫表面得到多孔坯体材料，坯体干燥后气氛烧结制得石墨烯/生物玻璃多孔支架。本项目拟一方面通过蛋清蛋白质变性程度的调控来获得稳定的泡沫，得到均匀分布、孔径可调的微观孔结构，以提高多孔支架的机械性能。另一方面利用具有优异机械性能的石墨烯与生物玻璃颗粒界面复合，进一步提高多孔支架机械性能。这种结合蛋白质发泡法对微观孔结构调控以及复合石墨烯来提高生物玻璃多孔支架机械性能的研究思路具有创新性。本项目对于拓展石墨烯在生物医学方面的应用，探索生物玻璃多孔支架应用于骨组织工程支架具有重要意义。

多孔材料作为新型结构功能材料，有广泛的应用。探寻微观孔洞结构和分布的调控机制是应用的基础。本研究主要选取蛋白质发泡法作为研究对象，探寻多孔材料微观结构的调控方法，已获得国家发明专利一项。蛋白质发泡法是通过蛋白质的互相缠绕交联来稳定泡沫的气液两相界面形成液膜，液膜表面最后形成了孔壁而韧带在液膜之间形成，这是一种非常均匀分布的孔洞结构。本研究首先将蛋白质发泡法应用于泡沫炭的制备（Mater. Lett. 他引9次），制备出圆形孔壁致密韧带的多孔结构，通过浆料的黏度调控了泡沫炭的密度进而调控了压缩强度。利用中间相炭微球在液膜上分散于延迟焦粉末之间，即起到了机械增强效应，又没有提高泡沫炭的导热系数。本研究进一步制备出中间相沥青、短切碳纤维和蔗糖泡沫炭。与常见的中间相沥青自发泡法相比，蛋白质发泡法可以通过中间相沥青或者蛋白质含量调节孔隙率，氧化处理过的中间相沥青发泡得到强度更高的泡沫炭。较短的短切碳纤维能制备出孔洞结构完整的泡沫炭，通过蛋白质含量调节孔隙率和压缩强度。蔗糖泡沫炭具有本研究中最低的导热系数，通过增加蔗糖含量减少了韧带上的孔洞，提高了自身的压缩强度。..另外本研究还开展了氧化石墨烯作为3D打印聚乳酸/阿拉伯树胶复合支架增强相的工作。0.5%氧化石墨烯的含量不但可以增加复合支架的压缩强度，而且对成骨细胞的生长也优于过多或过少的氧化石墨含量。兔子上肢大段骨缺陷模型实验也证明含有少量氧化石墨烯可以完全促进骨头的复原。..由于蛋白质发泡法可以多层次的调控孔洞结构，值得应用于更广泛的多孔材料制备。氧化石墨烯是骨组织工程支架材料的有益增强相。