纳米簇中金属混合价态和细胞内氧化还原电对的偶联及荧光成像研究

Changes in intracellular redox state is always intimate with the important transition points of the cell cycle, such as proliferation, differentiation and senescence. The well-accepted quantitative description method of intracellular redox state is to determine the concentration ratio of intracellular redox pairs, such as GSH/GSSG. The traditional method for determination of GSH/GSSG is based on fluorescent proteins probes prepared by tedious procedures, which show a diffusion process-limited fluorescent response to redox pairs due to the large sizes of proteins. Metal nanoclusters (NCs), composed of several to tens of metal atoms, show small size, good photostability and biocompatibility. Our previous work has shown that it may be also effective to detect GSH/GSSG redox pairs in virtue of the fluorescent responses induced by the changes of metal mixed valence states inside NCs. However, the mechanism is still unclear. In this project we intend to investigate the coupling processes of GSH/GSSG redox pair and metal mixed valence states of NCs and its regulation on the fluorescence efficiency of NCs to explore the interaction mechanisms. This allows the rational design and screening of efficient and simple NCs probes for intracellular GSH/GSSG redox pairs, and offers important scientific tools for low-cost and sensitive imaging of redox states in living cells.

细胞内氧化还原状态的变化始终与细胞生命循环的重要过渡阶段如增殖、分化和衰老密切相关。对细胞内的氧化还原状态公认的定量描述方法是测定细胞内GSH/GSSG等关键电对的浓度比。目前定量GSH/GSSG等电对基本采用荧光蛋白类探针，其制备过程复杂；而且探针尺寸很大，荧光响应易受扩散过程制约。金属纳米簇由几个到数十个金属原子组成，具有尺寸小、光稳定性和生物相容性好等特点。我们的前期工作表明，借助纳米簇内金属混合价态变化导致的荧光变化，也可能有效检测GSH/GSSG等氧化还原电对，但其机制还不清楚。本项目我们拟考察GSH/GSSG等电对与纳米簇的金属混合价态电对的偶联过程及其对纳米簇的荧光效率的调控，探索其作用机理，设计筛选高效、简便的细胞内GSH/GSSG等电对的纳米簇成像探针，为低成本、高灵敏的活细胞氧化还原状态成像提供重要的科学工具。

细胞内氧化应激与增殖、衰老和癌变等重要生理过程密切相关，对该水平的检测与调控将直接影响细胞的命运。本项目围绕金纳米簇等与细胞氧化还原环境的相互作用，发展其高灵敏生物检测、荧光成像及肿瘤诊疗应用，取得一系列成果：1）建立了细胞内氧化应激水平的有效评价方法。设计硫醇类氨基酸/小肽、核苷酸等保护的金簇探针，通过配体特异性交换等特性，实现细胞内谷胱甘肽等分子的快速成像和高灵敏检测。2）构建了基于氧化应激介导的多药耐药细菌抑杀新方法。通过金簇及其复合物破坏原核细胞膜、损伤基因组DNA和过氧化物模拟酶效应联合来抑杀多药耐药细菌。3）提出了基于细胞氧化应激微环境的肿瘤诊疗一体化途径。利用氧化应激微环境触发金纳米结构的级联聚集和可控释放，结合光声成像和近红外光热疗策略，实现了肿瘤诊疗一体化。相关工作在Chem, Small, Chem. Mater.等期刊上发表SCI论文42篇（含中科院1区论文12篇），EI论文1篇。研究成果引起国际同行的广泛关注，已被Chem. Soc. Rev., J. Am. Chem. Soc., Angew. Chem. Int. Ed.等权威期刊他引200余次。项目资助申请了国家发明专利4项，获国家发明专利授权1项。相关工作作为代表性成果获江苏省科学技术二等奖和三等奖各1项。