A dual mode turn-on probe for H₂O₂ sensing via fluorescence and colorimetry in live cells and serum

Hydrogen peroxide (H₂O₂), as a crucial intracellular reactive oxygen species (ROS) and secondary messenger, plays a key role in various physiological and pathological processes. Therefore, accurate detection of H₂O₂ is of great significance for investigating disease mechanisms. In this study, a novel fluorescence and colorimetric dual-mode probe, Re-FS, was designed and synthesized based on a resorufin (Re) scaffold, employing a pentafluorobenzenesulfonyl (FS) group as the recognition moiety. Upon reaction with H₂O₂, the FS group undergoes a nucleophilic substitution reaction, releasing Re and triggering a fluorescence "turn-on" response accompanied by a distinct color change. The detection limits were determined to be 5 µM for the fluorescence mode and 10 µM for UV-vis mode, both exhibiting a linear range of 0-1 mM. Benefiting from the strong electron-withdrawing effect of the fluorine atoms in the FS group, the probe demonstrates excellent selectivity against various potential interferents. It has been successfully applied for the effective sensing and imaging of H₂O₂ in serum and living cell environments. Furthermore, the visible color transition of the probe solution facilitates the development of a portable H₂O₂ visual detection platform based on smartphone RGB analysis. This dual-mode detection strategy enables cross-validation of results, providing a promising tool for monitoring neurodegenerative diseases.