铁蛋白-多糖为载体的花青素纳米运载体系的自组装构建机制及细胞吸收效应研究

Anthocyanidin, the most effective natural water-soluble free radical scavenger so far, its physiological activities have been restricted significantly in vivo caused by low stability, cell uptake efficiency and bioavailability. It was found that ferritin had a unique structure of nano cavity and multiple reaction interfaces in our previous studies. In this research, biochemical techniques will be employed to transform the natural nano-biological protein ferritin into a bionano-reactor. The anthocyanidin will then be integrated effectively into the modified ferritin reactor during subunits reassembling process with precise molecular level control. By the control of experimental conditions, such as pH, ionic strength, the electrostatic binding and modification effect of two different kinds of polysaccharides on ferritin nano-carrier will be systematically adjusted, in order to fabricate an effective delivery system. The double protection and synergistic stabilization effect of ferritin and polysaccharides on anthocyanidin will also be clarified, and the promoting effect on uptake efficiency of anthocyanin by a ferritin receptor-mediated process will be tested through Caco-2 cell monolayers. This study will provide scientific evidences for construction mechanism and molecular interactions of ferritin-polyasccharide-anthocyanin nano delivery system, and guidance of promotion effect on stability and absorption of anthocyanin as well.

花青素是目前发现的最有效的天然水溶性自由基清除剂，然而较低的稳定性、细胞吸收率和生物利用度极大地限制了其在机体内多种生理活性的发挥。在前期研究发现铁蛋白具有独特的纳米空腔结构和多反应界面的基础上，本项目将采用生化手段将铁蛋白改造成纳米空腔反应器，利用亚基可逆自组装特性，在分子水平上将花青素有效嵌入改性后的铁蛋白反应器；进而选择不同类型的多糖分子，通过环境条件，如pH、离子强度等参数系统化调控多糖对蛋白载体的静电修饰作用，构建有效的三元运载体系；同时阐明铁蛋白和多糖对花青素的双重保护和协同稳定效果，并通过Caco-2细胞模型检验纳米运载体系中花青素的细胞吸收效果，验证载体中的花青素能否通过细胞上铁蛋白特异性受体被直接吸收。本课题的实施对认识三元纳米运载体系的构建机制和各组分间分子作用模式以及改善花青素稳定性和吸收效果具有重要意义。

花青素被认为是目前发现的最有效的天然水溶性自由基清除剂，能够有效地抑制自由基，从而可以预防糖尿病、高血压和其它与氧化应激相关的疾病。然而，较低的稳定性、细胞吸收率和生物利用度极大地限制了花青素在机体内多种生理功能的发挥。本项目首先制备了铁蛋白纳米空腔反应器，利用pH值调控的亚基可逆自组装特性，在铁蛋白解离-重组过程中从分子水平上将花青素有效嵌入铁蛋白反应器内部，继而通过静电相互作用，在铁蛋白纳米反应器表面结合多糖海藻酸钠，形成多糖修饰保护层，获得粒径150-200 nm左右的均匀分布的花青素复合纳米颗粒。通过铁蛋白和多糖双重保护和协同稳定作用，显著地降低了花青素在紫外线、高温、金属离子等不利条件下的降解作用，稳定性显著提升。在模拟体外胃肠消化环境中，复合纳米载体可延缓花青素在胃环境中的释放，展现出良好的肠溶和缓释性能。通过Caco-2细胞模型，证明复合纳米颗粒显著提高了花青素的细胞吸收效率。通过本课题的实施，对认识三元纳米运载体系的构建机制和各组分间分子作用模式以及改善花青素稳定性和吸收效果具有重要意义。