College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 199 Ren'Ai Road, Suzhou 215123, China.
J Mater Chem B. 2020 Aug 26;8(33):7466-7474. doi: 10.1039/d0tb01377c.
Four different neutral fluorescent markers containing nitrogen heterocycles (quinoxaline, 1H-pyrazolo[3,4-b]pyridine, 1H-indazole and 1H-pyrrolo[2,3-b]pyridine) as targeting groups were designed and prepared in order to screen out structural units for targeting mitochondria. Several classical fluorophores (coumarin, 1,8-naphthalimide and Nile Red) were connected with these heterocycles via Suzuki coupling reactions. The derivatives of coumarin (dyes 1a and 2a-c) and 1,8-naphthalimide (dyes 3a-c) fluoresced in the blue-green region, while the Nile Red derivatives (dyes 1b and 4a-c) fluoresced in the red light region. The optical properties of the classical fluorophores, such as emission properties and photostability, were retained in the new dyes. All of them showed low cytotoxicity. Confocal fluorescence experiments in L929 normal cells and HeLa cancer cells indicated that dyes 1a-b targeted dual sites of mitochondria and lipid droplets. Moreover, dyes 2a-c, 3a-c and 4a-c targeted mitochondria; meanwhile, there are only a few mitochondria-targeting markers with neutral skeletons. Furthermore, it was found that nitrogen heterocycles with N-H bonds can improve the mitochondrial targeting ability of partial neutral fluorophores.
为了筛选靶向线粒体的结构单元，设计并合成了 4 种含有氮杂环（喹喔啉、1H-吡唑并[3,4-b]吡啶、1H-吲唑和 1H-吡咯并[2,3-b]吡啶）作为靶向基团的新型中性荧光染料。通过 Suzuki 偶联反应，将几种经典荧光团（香豆素、1,8-萘酰亚胺和尼罗红）与这些杂环连接。香豆素衍生物（染料 1a 和 2a-c）和 1,8-萘酰亚胺衍生物（染料 3a-c）在蓝绿光区有荧光发射，而尼罗红衍生物（染料 1b 和 4a-c）在红光区有荧光发射。新染料保留了经典荧光团的光学性质，如发射性质和光稳定性。所有染料的细胞毒性均较低。在 L929 正常细胞和 HeLa 癌细胞中的共聚焦荧光实验表明，染料 1a-b 靶向线粒体和脂滴的双重部位。此外，染料 2a-c、3a-c 和 4a-c 靶向线粒体；同时，具有中性骨架的线粒体靶向标记物很少。此外，还发现具有 N-H 键的氮杂环可以提高部分中性荧光团的线粒体靶向能力。
