A 3,5-dinitropyridin-2yl substituted naphthalimide-based fluorescent probe for the selective detection of biothiols and its application in cell-imaging.

A naphthalimide-based fluorescent probe was developed for the sensitive and selective detection of biothiols. The fluorescence of the probe was quenched by the electron-withdrawing 3,5-dinitropyridin-2-yl group via the photoinduced electron transfer process, and turned on by biothiol-triggered nucleophilic aromatic substitution. The sensing mechanism was confirmed by HPLC analysis and theoretical calculations. The probe shows a satisfactory response time of 30 min with low detection limits (Cys: 0.32 µM; Hcy: 0.88 µM; GSH: 0.46 µM). Furthermore, the probe was successfully utilized to detect endogenous and exogenous biothiols in HeLa cells.