A unique NIR dye constructed mitochondrial anchoring fluorescent probe for highly selective selenocysteine detection and imaging in living cells and mice

Fluorescence imaging plays an increasingly important role in biomedicine field due to its superior sensitivity and selectivity along with dynamic, real-time, in situ monitoring the occurrence and development of biological events. Therefore, it is crucial to construct a near-infrared (NIR) fluorescent molecule with excellent optical properties. Herein a NIR robust out mitochondria-targeting dye NN has been designed, synthesized and characterized, whose fluorescence properties are easily adjusted by changing the substitution position of the nitro group at the benzene ring in this fluorescent dye. NN was a unique fluorescence-enhanced nitro dye with high fluorescence quantum yields∼0.17, a large Stokes shift∼120 nm and stable chemical structure. Encouraged by this, a novel fluorescent probe NN-Sec based on intramolecular charge transfer (ICT) was constructed by grafting NN with a selenocysteine (Sec) recognition group 2,4-dinitrobenzenesulfonyl (DNBS), and it exhibited a targeted ability with great sensitivity and selectivity. Subsequently, the probe was used for NIR imaging in living cells and mice, and deep imaging results further illustrate its potential application in biosystems. The successful design of NN and NN-Sec offer a valuable theoretical basis and technical support for investigating the occurrence and development of Sec-related diseases.