A mitochondria-targeting ratiometric fluorescent probe for imaging hydrogen peroxide with long-wavelength emission and large Stokes shift

Hydrogen peroxide, one of the curial reactive oxygen species, is believed to involve in a wide range of physiological processes. In this work, we designed and synthesized a new fluorescent probe, HKB, for the detection of hydrogen peroxide, by taking advantage of the combination of ICT and ESIPT mechanisms. Different from other benzothiazole-based ratiometric probes, the intramolecular ESIPT process is preserved in probe HKB and the large Stokes shift is remained. Probe HKB displayed significant ratiometric fluorescence variations (I594nm/ I666nm) upon the addition of 50 equiv. of hydrogen peroxide under a single-wavelength excitation at 440 nm in PBS buffer (pH = 7.0, 10 mM, 30% CH3CN) and showed a large Stokes shift change from 102 nm to 254 nm. Moreover, this probe exhibited excellent mitochondria targeting property with a 0.94 Pearson’s colocalization coefficient using Rh123 as a reference. Gratifyingly, preliminary biological experiments indicated that probe HKB could sense both the exogenous and endogenous hydrogen peroxide in living HeLa cells.