A novel coumarin-derived fluorescent probe for real-time detection of pH in living zebrafish and actual food samples.

• A new fluorescent probe DIC was designed baed pn cumarin-based. • DIC could sensitively sense alkaline pH with the pKa value of 8.12. • DIC exhibited excellent photostability and reversibility in the pH detection. • DIC was employed for in-suit tracking of pH fluctuations in living zebrafish. A coumarin-based fluorescent probe DIC (3-(2-(5-(4-(diphenylamino)phenyl)isoxazol-3-yl)-1-hydroxyvinyl)-7-hydroxy-2H-chromen-2-one) with high performance was exploited for detecting pH changes in biological system and food samples. The probe DIC could sensitively sense alkaline pH fluctuations in the range of 6.50‒9.98 with the pKa value of 8.12 through a remarkable fluorescence turn-on process. The probe DIC exhibited excellent photostability and reversibility in monitoring the pH fluctuations. The detection mechanism of DIC for pH was confirmed by 1H NMR titration experiment and theoretical calculation. This probe owned a low cytotoxicity and was successfully employed for in-suit tracking of pH fluctuations in living zebrafish. In addition, the probe DIC could be applied in the visualization of meat and prawn freshness. [Display omitted] [ABSTRACT FROM AUTHOR]