基于聚集诱导发光的线粒体靶向过氧化氢荧光探针的合成及性能研究

Given that aberrant accumulation of mitochondrial H2O2 is closely related to many major diseases, mitochondria-targeted H2O2 fluorescent probes have drawn much attention. However, the already known probes generally possess some drawbacks such as poor water solubility and aggregation-caused quenching, which severely restricted their practicability. The purpose of this project is to synthesize some mitochondria-targeting fluorescent probes for H2O2 detection based on aggregation-induced emission (AIE) effect, which is realized by connecting an integrated unit containing a phenylboronate H2O2 recognition group, a mitochondrial targeting group and a hydrophilic side chain onto the structurally modified tetraphenylethylene derivative that acts as an AIE-active luminogen (AIEgen). The specific reaction of phenylboronate with H2O2 was applied to trigger self-immolation of the external groups to release AIEgen, thus realize H2O2 detection based on AIE effect. Through investigating the H2O2 recognition properties, bioimaging applications, and mitochondrial localization functions of the probes, the relationship between probe structure and recognition property will be elucidated. We strive to obtain a series of fluorescent probes with high selectivity and sensitivity for the detection of mitochondrial H2O2, which will provide theoretical and experimental basis for further exploration of AIE-based mitochondria-targeting H2O2 fluorescent probes. The research results are important for the applications of AIE-based fluorescent probes to chemical analysis, environmental monitoring and medical diagnosis.

鉴于线粒体中H2O2浓度异常累积与诸多重大疾病密切相关，线粒体靶向H2O2荧光探针备受关注。但已有探针普遍存在水溶性差、聚集荧光猝灭等缺陷，严重制约了其实用性。本项目拟基于聚集诱导发光（AIE）效应，以四苯乙烯衍生物为AIE活性荧光团（AIEgen），通过引入兼具苯硼酸酯类H2O2识别基团、线粒体靶向基团及亲水性侧链的一体化结构单元，合成线粒体靶向H2O2荧光探针。利用苯硼酸酯与H2O2的特异性反应触发外接基团的自脱落而释放出AIEgen，实现基于AIE效应的H2O2检测。考察探针对H2O2的识别性质、线粒体定位功能及生物成像，阐明探针分子结构与识别性能间的构-效关系，力求获得系列高选择性、高灵敏度检测线粒体H2O2的荧光探针，为深入探索基于AIE效应的线粒体靶向H2O2荧光探针提供理论基础和实验依据。研究结果对基于AIE效应的荧光探针在化学分析、环境监测及医学诊断领域的应用具有重要意义。

线粒体内过氧化氢（H2O2）是线粒体ROS主要组成部分，对线粒体氧化还原稳态起着重要作用。线粒体H2O2的异常则会导致多种疾病，因此研究开发线粒体靶向的H2O2荧光探针受到了越来越多的关注。为克服已有荧光探针普遍存在的水溶性差、易受聚集荧光猝灭影响等缺陷，本项目以具有聚集诱导发光（AIE）性质的四苯乙烯类、苯并噻唑类以及三苯胺类荧光团为基本AIE活性结构单元，设计合成了系列基于AIE机制的荧光探针。通过在探针分子结构中引入H2O2识别基团和线粒体靶向基团，实现了线粒体靶向的H2O2识别。考察了探针分子中的AIE基元结构、检测机制等对探针检测性质的影响。实验表明，在延展AIE基团共轭体系的同时，引入H2O2识别基团和线粒体靶向基团，通过反应性识别引发的自脱落过程对分子内电荷转移（ICT）效应的调控，可有效避免识别前后发射光谱的重叠现象。在靶向识别一体化结构单元方面，优化了研究策略，通过利用亚硫酸氢根参与的迈克尔加成反应阻断共轭结构的方法抑制探针的AIE性质，引入的阴离子型H2O2识别基团可提高产物的水溶性，再利用反应的可逆性用H2O2氧化亚硫酸氢根使加成产物发生消除得到原始探针结构，恢复其AIE特性和线粒体靶向功能。通过这种先加成后消除的分步策略发展了AIE性质调控的新途径。此外，对研究过程中发现的其他具有AIE性质的荧光探针也进行了探索性研究，并取得了一些有意义的研究结果。通过本项目研究，丰富了基于AIE机制荧光探针的调控策略，所取得的研究结果可为深入探索基于AIE效应的线粒体靶向H2O2荧光探针提供理论基础和实验依据。