Characterization of a Cu$^{2+}$-selective fluorescent probe derived from rhodamine B with 1,2,4-triazole as subunit and its application in cell imaging

Abstract

A rhodamine B derivative containing 1,2,4-triazole as subunit was characterized as an off-on type Cu$^{2+}$-selective fluorescent probe. It exhibited high selectivity and sensitivity for Cu$^{2+}$ in ethanol-water solution (9:1, v:v, pH 7.0, 20 mM HEPES) and underwent ring opening. A prominent fluorescence enhancement at 570 nm was observed in the presence of Cu$^{2+}$ with the change in the absorption spectrum, and a 1:1 metal-ligand complex was formed. With the optimized experimental conditions, the probe exhibited a dynamic response range for Cu$^{2+}$ from 8.0 $\times $ 10$^{-7}$ to 7.5 $\times $ 10$^{-6}$ M with a detection limit of 2.3 $\times $ 10$^{-7}$ M in ethanol-water solution (9:1, v:v, pH 7.0, 20 mM HEPES). Its application in Cu$^{2+}$ imaging in living cells was also studied.