Designing an ESIPT-based fluorescent probe for imaging of hydrogen peroxide during the ferroptosis process.

Hydrogen peroxide (HO), depending on its levels, plays a crucial role in either modulating various biological processes as a signal molecule, or mediating oxidative damage as a toxin. Therefore, monitoring intracellular HO levels is pivotal for exploring its physiological and pathological roles. Using a modified 2-(2'-hydroxyphenyl) benzothiazole (HBT) as the fluorophore, and a pinacol phenylborate ester as the responsive group, herein we developed an excited-state intramolecular proton transfer (ESIPT)-based probe BTFMB. The probe exhibited turn-on fluorescence response, large Stokes shift (162 nm) and low detection limit (109 nM) toward HO, and was successfully applied for monitoring exogenous and endogenous production of HO, and identifying accumulation of HO during the ferroptosis process.