A highly selective AIEgen fluorescent probe for visualizing Cys in living cells and C. elegans

Abstract

As essential biological thiols in organisms, Cys, Hcy, and GSH are closely related to each other, and they can be involved in various pathological processes if expression levels are abnormal. It is a challenge to develop effective fluorescence-based tools to selectively distinguish Cys from Hcy and GSH because of their common functional groups. For most existing Cys fluorescent probes, their application is greatly restricted by the influence of aggregation-caused quenching (ACQ). In this work, a novel fluorescent probe, PE-YW, for Cys was designed rationally via regulating its AIE-based effects. The probe PE-YW took advantage of a specific conjugate addition cyclization reaction between Cys and an acrylate moiety, inducing the aggregation of PE-OH and showing large turn-on fluorescence (about 7-fold). The probe could detect Cys over other amino acids with high selectivity and a low detection limit (LOD = 1.72 nM). In addition, PE-YW exhibited excellent performance, such as a high fluorescence quantum yield (δ = 0.8) and a fast response toward Cys (<20 min). Furthermore, PE-YW was used for fluorescence imaging in living HeLa cells and C. elegans. The results suggested that PE-YW was a suitable and potential fluorescence-based tool for detecting Cys in living systems.