Imidazole-centred cupric ions sensor: Experimental validation, theoretical understanding, and zebrafish bioimaging

In this study, we have developed an imidazole centered fluorescent probe 3-(2-(2-(5-bromo-2-hydroxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)thiazol-4-yl)-6-chloro-2H-chromen-2-one (SICT), achieving exceptional selectivity for Cu²⁺ ion detection. These probes exhibit rapid responsiveness (109 nM detection limit) and strong binding constants (0.214 × 10⁵ M⁻¹). Employing an aqueous ethanol system, we assessed their sensing capabilities through both in vitro and in vivo studies, using zebrafish as our model organism. Notably, the SICT probe displays a high quantum yield of 0.62 and follows a 1:1 binding mechanism with Cu²⁺ ions, validated by Job's plot and ESI-Mass spectrum analyses. Furthermore, our probe demonstrates minimal cytotoxicity in both in vitro (MDA-MB-231 cells) experiments. These promising results motivate us to apply the SICT probe for intracellular Cu²⁺ ion tracking in zebrafish embryos, showcasing its potential in diverse fields like biomedicine and environmental monitoring.