N-端修饰肽保护金属簇的定向聚集复合组装体构建及细胞内蛋白酶活性分析

The accurate construction of hierarchy self-assembly is of great significance to analytical measurements. Although the directed assembly and aggregation-induced emission of precious metal nanoclusters have been currently reported in non-aqueous media, it is still a challenge to precisely regulate the directed aggregation events by nanoclusters in aqueous system and to develop the rapid and specific analytical methods in complex biological environments. The applicant has recently found that non-assembled N-acetyl modified peptide ligands can induce directed aggregation emission of precious metal nanoclusters in aqueous phases. So this project will focus on this discovery to explore the mechanism of directed aggregation by adjusting the sequence and modification groups of short peptides. Then the peptide segments of protease substrate will be used to link the non-assembled short peptides protected nanoclusters and known self-assembled peptides for the construction of hierarchy composite assembly structures. In virtue of the regulation of aggregation behaviors of composites by cytoplasmic proteases, a novel series of imaging probes will be constructed with high sensitivity, rapid response and anti-interference, using the cysteine-containing aspartate specific protease (caspase) family as a model. The present design integrates the hydrogen bonds, hydrophilicity, pi-pi stacking interaction from self-assembled peptides and metal coordination interaction from non-assembled short peptides protected metal nanoclusters, which will greatly enrich the analytical measurement methods of the key intracellular protease targets.

有序自组装体的精确构建对分析测量学的发展有着重要意义。目前非水介质中贵金属纳米簇的定向组装和聚集诱导发光已有报道，但在水相体系精确调控纳米簇定向聚集事件，并基于此发展复杂生物环境下快速、特异的分析方法仍具有挑战性。申请人最近发现非自组装的N-乙酰基修饰短肽配体可在水相诱导贵金属纳米簇定向聚集发光行为。本项目拟围绕该发现展开研究，通过调节短肽序列和N-端修饰基团来探索定向聚集内在机制；进而以蛋白酶底物肽段等衔接非自组装肽保护的纳米簇和常规自组装肽，构建有序复合组装体；利用胞质蛋白酶调控复合组装体的聚集行为，以天冬氨酸特异性半胱氨酸蛋白酶(caspase)家族为模型构建高灵敏、快速响应、耐干扰的新型细胞内蛋白酶水平的成像探针和细胞功能调控方法。该设计融合自组装肽段内的氢键、亲疏水、pi-pi堆积作用和非自组装短肽保护纳米簇内的金属配位作用，将有力拓展细胞内蛋白酶类关键靶标的分析测量思路。

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