Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science , Northwest University , Xi'an , Shaanxi 710127 , People's Republic of China.
Shaanxi Key Laboratory of Catalysis, School of Chemistry and Environment Science , Shaanxi University of Technology , Hanzhong , Shaanxi 723000 , People's Republic of China.
Anal Chem. 2018 Mar 20;90(6):4119-4125. doi: 10.1021/acs.analchem.8b00066. Epub 2018 Feb 28.
Selenocysteine (Sec) is a primary kind of reactive selenium species in cells, and its vital roles in physiological processes have been featured. Thus, the development of highly sensitive and selective methods for the sensing of Sec is of great significance. This work reports a turn-on fluorescent probe for selenol based on the unique fluorescence OFF-ON switching between the Schiff base (SB) and its complementary protonated Schiff base (PSB) form of merocyanine dyes. The probe consists of a merocyanine Schiff base fluorophore and a 2,4-dinitrobenzenesulfonamide moiety that reacts especially with selenol. The fluorescence turn-on response of MC-Sec is realized via the selective removal of the strongly electron withdrawing 2,4-dinitrobenzenesulfonyl group by Sec, leading to a shift in the p K of the imine nitrogen of the probe from 6.40 to 9.04 and thus significantly increasing the population of the fluorescent PSB form of the dye at physiological pH. MC-Sec shows good selectivity and sensitivity for Sec and has been applied in the imaging of exogenous and endogenous selenol in living cells by confocal fluorescence microscopy. The proposed mechanism should be useful for developing future probes directed to other target molecules by employing this simple but effective p K shift strategy.
硒代半胱氨酸（Sec）是细胞中主要的反应性硒物种，其在生理过程中的重要作用已得到证实。因此，开发高灵敏度和选择性的方法来检测 Sec 具有重要意义。本工作报道了一种基于甲川染料希夫碱（SB）与其互补质子化希夫碱（PSB）之间独特的荧光关闭-开启开关的基于硒醇的荧光探针。该探针由一个甲川希夫碱荧光团和一个 2,4-二硝基苯磺酰胺部分组成，该部分特别与硒醇反应。MC-Sec 的荧光开启响应是通过 Sec 选择性地去除强吸电子的 2,4-二硝基苯磺酰基来实现的，导致探针中亚胺氮的 pK 值从 6.40 转移到 9.04，从而在生理 pH 值下显著增加染料的荧光 PSB 形式的比例。MC-Sec 对 Sec 具有良好的选择性和灵敏度，并已通过共聚焦荧光显微镜应用于活细胞中外源和内源性硒醇的成像。所提出的机制通过采用这种简单但有效的 pK 转移策略，应该对开发针对其他靶分子的未来探针有用。
