Design, synthesis and application of dual-channel fluorescent probes for ratiometric detection of HClO and H2S based on phenothiazine coumarins

Abstract

The ubiquity of diverse material entities in environmental matrices renders the deployment of unifunctional fluorescent indicators inadequate. Consequently, this study introduces a ratiometric dual-emission fluorescent sensor (Probe CP), synthesized by conjugating phenothiazine coumarin to hydroxycoumarin through a piperazine linker for concurrent detection of HClO and H₂S. Upon interaction with HClO, the phenothiazine unit's sulfur atom undergoes oxidation to sulfoxide, facilitating a shift from red to green fluorescence in a ratiometric manner. Concurrently, at the opposite terminus of Probe CP, 2,4-dinitroanisole serves as the reactive moiety for H₂S recognition; it restores the blue emission characteristic of 7-hydroxycoumarin while maintaining the red fluorescence emanating from phenothiazine coumarin as an internal standard for ratio-based assessment. Exhibiting elevated specificity and sensitivity coupled with minimal detection thresholds (0.0506 μM for HClO and 1.7292 μM for H₂S) alongside rapid equilibration periods (3 min for HClO and half an hour for H₂S), this sensor was efficaciously employed in cellular environments and within zebrafish models as well as imaging applications pertaining to alcohol-induced hepatic injury in murine subjects.

Keywords: Bioimaging; Fluorescent probes; Hydrogen sulfide; Hypochlorite.