A novel thiophene-based fluorescent chemosensor for the detection of Zn²⁺ and Cn⁻: Imaging applications in live cells and Zebrafish

A novel fluorescent turn-on chemosensor DHADC ((E)-3-((4-(diethylamino)-2-hydroxybenzylidene)amino)-2,3-dihydrothiophene-2-carboxamide) has been developed and used to detect Zn²⁺ and CN⁻. Compound DHADC displayed a notable fluorescence increase with Zn²⁺. The limit of detection (2.55 ± 0.05 µM) for zinc ion was far below the standard (76 µM) of the WHO (World Health Organization). In particular, compound DHADC could be applied to determine Zn²⁺ in real samples, and to image Zn²⁺ in both HeLa cells and zebrafish. Additionally, DHADC could detect CN⁻ through a fluorescence enhancement with little inhibition with the existence of other types of anions. The detection processes of compound DHADC for Zn²⁺ and CN⁻ were demonstrated with various analytical methods like Job plots,¹H NMR titrations, and ESI-Mass analyses.