A hemicyanine-based fluorescent probe for detection of pH and its applications in live cells imaging and food monitoring.

[Display omitted] • A new pH-sensitive fluorescent probe 1 based on hemicyanine fluorophore is developed. • The probe can respond to pH with high selectivity and sensitivity. • The probe can solely illumine the lysosomes and detect the exogenous pH difference in live cells. • The probe can successfully monitor the pH changes during food spoilage. pH as an important parameter is closely related to many pathological processes and food freshness. In this paper, a new pH-sensitive fluorescent probe 1 based on hemicyanine dye was synthesized and used for the detection of pH in live cells and food spoilage. Under neutral and alkaline conditions, the phenolic hydroxyl group of the probe deprotonates, forming a closed spirocyclic structure and resulting in fluorescence quenching. Under acidic conditions, the probe maintains an open-loop structure and has intense fluorescence. The probe possessing good selectivity and stability can target lysosomes and visualize the exogenous pH in live cells. Furthermore, by using this probe, we successfully achieved the monitoring of pH in metamorphic process of shrimp and pork. This probe is expected to provide a good imaging tool for real-time detection of pH in live cells and food monitoring. [ABSTRACT FROM AUTHOR]