A Simple Fluorescent Probe for Biothiols Detection and Imaging of Living Cells In Vivo Based on a Hemicyanine Derivative.

Biothiols play essential roles in various biological processes and are closely associated with diseases such as cancer, neurodegenerative disorders, and cardiovascular diseases. To monitor biothiols in organisms and living cells, we developed a novel intramolecular charge transfer (ICT)-based probe, hemicyanine-2,4-dinitrobenzenesulfonamide(HCD), by coupling a hemicyanine dye with 2,4-dinitrobenzenesulfonyl chloride.The HCD probe exhibits remarkable sensitivity, with low detection limits of 0.32 µM for Cys, 0.72 µM for Hcy, and 0.27 µM for GSH, and demonstrates high selectivity for biothiols in the presence of various interfering species. The detection mechanism was thoroughly validated using high-resolution mass spectrometry (HRMS), UV-Vis spectroscopy, fluorescence spectroscopy and Density Functional Theory (DFT) calculation. Furthermore, the applicability of HCD was successfully demonstrated in human urine samples and in vivo settings using RAW264.7 cells, confirming its potential as a powerful tool for monitoring endogenous biothiols in biological systems.