College of Chemistry, Chemical Engineering and Material Science, Soochow University, 199 Ren'Ai Road, Suzhou 215123, China.
State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China.
Org Biomol Chem. 2022 Jul 20;20(28):5558-5565. doi: 10.1039/d2ob01095j.
In this paper, two cationic probes 1a and 1b and a neutral dye 1c were successfully designed and synthesized according to the Knoevenagel condensation reaction, which combines the good optical properties of hemocyanine and the biocompatibility of nitrogen-containing heterocyclic rings based on a quinoxaline skeleton. Probes 1a and 1b showed an OFF-ON fluorescence response to nucleic acids with excellent selectivity. Specifically, the fluorescence intensity of probe 1a was enhanced by 18 and 133 times, respectively, along with the increase of DNA or RNA concentrations (0-600 μg mL). Furthermore, a good linear correlation between the fluorescence intensity of probes 1a and 1b and the concentrations of DNA or RNA (0-350 μg mL) was obtained. In particular, the maximum emission wavelengths of probes 1a and 1b reached the near-infrared region (660-664 nm) when DNA or RNA was detected, which might reduce the light damage to cells and facilitate cell experiments. Fluorescence imaging revealed that all three dyes could be localized in the mitochondria of HeLa cells. The difference was that probes 1a and 1b could stain the nucleic acid in the mitochondria, while dye 1c was only a neutral mitochondrial biomarker. The results indicated that probes 1a and 1b are promising in the development of low toxicity mitochondrial nucleic acid probes and are expected to be used in monitoring the normal state of mitochondrial nucleic acids for living cells, which will help improve the situation in that currently reported studies of fluorescent probes are mainly focused on the nucleic acids in the nucleus, but less so on DNA in the mitochondria.
本文基于醌喔啉骨架，通过 Knoevenagel 缩合反应成功设计并合成了两种阳离子探针 1a 和 1b 以及一种中性染料 1c。探针 1a 和 1b 对核酸具有优异的选择性的 OFF-ON 荧光响应。具体而言，探针 1a 的荧光强度分别增强了 18 倍和 133 倍，而随着 DNA 或 RNA 浓度（0-600 μg mL）的增加。此外，探针 1a 和 1b 的荧光强度与 DNA 或 RNA 的浓度（0-350 μg mL）之间存在良好的线性相关性。特别是，当检测 DNA 或 RNA 时，探针 1a 和 1b 的最大发射波长达到近红外区域（660-664 nm），这可能会降低对细胞的光损伤，便于细胞实验。荧光成像表明，三种染料均可定位于 HeLa 细胞的线粒体中。不同之处在于，探针 1a 和 1b 可以染色线粒体中的核酸，而染料 1c 只是中性的线粒体生物标志物。结果表明，探针 1a 和 1b 有望开发出低毒性线粒体核酸探针，并有望用于监测活细胞中线粒体核酸的正常状态，这将有助于改善目前报道的荧光探针研究主要集中在核内核酸而较少关注线粒体 DNA 的情况。
