Highly Sensitive and Fast Responsive Fluorescence Turn‐On Chemodosimeter for Cu2+ and Its Application in Live Cell Imaging

Abstract

A rhodamine B derivative 4 containing a highly electron‐rich S atom has been synthesized as a fluorescence turn‐on chemodosimeter for Cu 2+. Following Cu 2+‐promoted ring‐opening, redox and hydrolysis reactions, comparable amplifications of absorption and fluorescence signals were observed upon addition of Cu 2+; this suggests that chemodosimeter 4 effectively avoided the fluorescence quenching caused by the paramagnetic nature of Cu 2+. Importantly, 4 can selectively recognize Cu 2+ in aqueous media in the presence of other trace metal ions in organisms (such as Fe 3+, Fe 2+, Cu+, Zn 2+, Cr 3+, Mn 2+, Co 2+, and Ni 2+), abundant cellular cations (such as Na+, K+, Mg 2+, and Ca 2+), and the prevalent toxic metal ions in the environment (such as Pb 2+ and Cd 2+) with high sensitivity (detection limit ≤10 ppb) and a rapid response time (≤1 min). Moreover, by virtue of the chemodosimeter as fluorescent probe for Cu 2+, confocal and two‐photon microscopy experiments revealed a significant increase of intracellular Cu 2+ concentration and the subcellular distribution of Cu 2+, which was internalized into the living HeLa cells upon incubation in growth medium supplemented with 50 μ M CuCl 2 for 20 h.