State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy, Key Laboratory of Functional Polymer Materials of Ministry of Education, Nankai University, Tianjin 300071, P. R. China.
School of Material Science and Engineering, Tiangong University, Tianjin 300387, P. R. China.
Anal Chem. 2020 Aug 4;92(15):10792-10799. doi: 10.1021/acs.analchem.0c02247. Epub 2020 Jul 21.
Endowing fluorogenic probes with ultrahigh contrast is essential to increasing the accuracy of fluorescence sensing and imaging. Phenolate-based D-π-A fluorophores (A-D) belong to a big family of fluorophores and have attracted increasing attention in fluorogenic probe design. However, the intrinsic dilemma of weak intracellular emission of traditional A-D fluorophores resulted in low contrast during live cell imaging. Herein, we present a general and robust approach to preparing novel A-D fluorophores with bright NIR fluorescence in living cells based on the unique halogen effects. The reported chlorinated A-D fluorophore () has an extremely strong fluorescence in an aqueous solution of pH 7.4 and living cells, which is 194 and 30 times higher than that of the traditional halogen-free analogue (), respectively. We systematically investigated and demonstrated that the distinct -I and +M halogen effects, which led to a drastic decrease in the p value and a significant enhancement in the fluorescence quantum yield, respectively, should be responsible for the tremendous fluorescence enhancement. The flexible phenol caging chemistry allows one to prepare multiple NIR fluorogenic probes based on the scaffold with high contrast for live cell imaging of a variety of analytes by introducing a corresponding triggering moiety. Moreover, the conjugated azide group of enables the integration of more functions as desired through a facile click reaction. A fluorogenic probe () was synthesized as a paradigm by equipping the scaffold with a mitochondria-targeting moiety and a peroxynitrite-responsive triggering group and demonstrated specific high-contrast fluorescence imaging of endogenous OONO in mitochondria of living macrophages.
赋予荧光探针超高对比度对于提高荧光传感和成像的准确性至关重要。基于酚的 D-π-A 型荧光团（A-D）属于一类大型荧光团，在荧光探针设计中受到越来越多的关注。然而，传统 A-D 荧光团的内在细胞内发射弱的困境导致在活细胞成像中对比度低。在此，我们提出了一种通用且稳健的方法，基于独特的卤族元素效应，在活细胞中制备具有明亮近红外荧光的新型 A-D 型荧光团。所报道的氯化 A-D 荧光团（）在 pH 7.4 的水溶液和活细胞中具有极强的荧光，分别比传统无卤类似物（）强 194 倍和 30 倍。我们系统地研究并证明，明显的-I 和+M 卤族元素效应分别导致 p 值急剧下降和荧光量子产率显著增强，这应该是荧光增强的主要原因。灵活的酚封闭化学允许人们通过引入相应的触发部分，基于 支架制备多种具有高对比度的近红外荧光探针，用于各种分析物的活细胞成像。此外， 的共轭叠氮基团可以通过简单的点击反应按需整合更多功能。通过在 支架上配备线粒体靶向部分和过氧亚硝酸盐响应触发基团，合成了一个荧光探针（）作为范例，并证明了内源性 OONO 在活巨噬细胞线粒体中的特异性高对比度荧光成像。
