A highly efficient turn-on fluorescent probe for the rapid and sensitive detection of cysteine

Abstract

Cysteine (Cys) plays a critical role in a variety of physiological and pathological processes; thus, it is meaningful to develop Cys-activated fluorescent probes with excellent sensing properties. Herein, we developed a series of fluorescent probe ML-1 to ML-4 capable of responding to Cys by decorating the phenyl or pyridine group at the terminal group of the α, β-unsaturated ketone unit. Experimental results showed that the probes containing pyridine units can respond more rapidly to Cys owing to the electron-deficient structure of the pyridine. Importantly, the mechanism involved in the rapid response of the probe ML-1 to Cys has been well elucidated. Further studies revealed that ML-1 performed desirable sensing properties toward Cys, such as efficient fluorescence turn-on ratio (up to 366.5-fold), fast response time (∼3 min), outstanding sensitivity (detection limit of 53.4 nM), and satisfactory specificity. Combined with its good biocompatibility, we demonstrated its potential application in monitoring the Cys fluctuations during isoniazid-induced liver injury progression.