Quantitatively analysis and detection of CN− in three food samples by a novel nopinone-based fluorescent probe

Cyanide (CN-) is one of the most lethal chemical substance and exists in the organisms and environment. Due to the CN- and CN--containing chemicals being widely applied in industrial fields and threatening human health, the sensitive and selective detection techniques towards CN- are still essential. Based on this, a "turn-on" fluorescent probe 2-(4-(5,5-dimethyl-4,5,6,7-tetrahydro-3H-4,6-methanobenzo[d]imidazol-2-yl)styryl)-3-ethylbenzo[d]thiazol-3-ium iodide (NCy) was designed and synthesized for monitoring CN-. NCy had a distinguishable color change towards CN- from colorless to yellow under 365 nm UV-light. NCy possessed the merits including low LOD (75 nM), good selectivity, and wide suitable pH range (4-10). The sensing mechanism of NCy towards CN- was proved by HRMS, 1H NMR titration and DFT analysis. Furthermore, the probe NCy was successfully utilized in detecting endogenous CN- in three food samples (green potato, cassava, and bitter almond) quantitatively. In bioimaging aspect, NCy was also successfully applied in detecting the exogenous CN- in living zebrafish.