A novel benzothiazole-based fluorescent probe for continuous detection of Cu2+/S2− and its application in cell imaging

In this paper, a fluorescent probe methyl( E )-2-(3-(benzo[ d ]thiazol-2-yl)-2‑hydroxy -5-methylbenzylidene) hydrazine-1-carboxylate ( DYH ) based on benzothiazole was designed and synthesized. The characterization involved NMR, HRMS, and crystal structure analysis. In case of the existence of other competing cations, the probe DYH showed high-affinity for Cu 2+ , and the resultant DYH Cu 2+ showed exceptional capacity to recognize S 2− in CH 3 CN/HEPES (7/3, v/v, HEPES 0.1 M, pH = 7.3). The detection limits of DYH for Cu 2+ and DYH Cu 2+ for S 2− were 0.56 μM and 0.67 μM, respectively. It was determined that the binding stoichiometry between the DYH and Cu 2+ , as well as DYH Cu 2+ and S 2− , was 1:1 according to the job's curve. The pH of the probe and complex was stable between 4 and 10. Colorimetric experiments of the probe DYH were conducted using test paper as a carrier. Additionally, DYH was used for fluorescence imaging of Cu 2+ and S 2− in Hela cells with poor cellular toxicity and good cell permeability.