A fluorescent probe based on the ESIPT (excited state intramolecular proton transfer) mechanism for rapid detection of endogenous and exogenous H2O2 (hydrogen peroxide) in cells

Hydrogen peroxide (H2O2) is one of the important reactive oxygen species in the body and can be used as a marker of some diseases such as cancer and neurodegenerative diseases. Therefore, it is of great significance to develop fluorescent probes that can detect H2O2 in living organisms for early diagnosis of diseases. However, slow response time and low fluorescence quantum yield limit the application of many probes. In this study, using 2-(2-hydroxyphenyl) benzothiazole (HBT) as the fluorophore, the introduction of weakly absorbing bromine atoms can accelerate the speed of electron transfer during the recognition process. Three ESIPT (excited state intramolecular proton transfer) fluorescent probes JLO/JLM/JLP were designed and synthesized. The detection of H2O2 can be achieved with all three probes, and we screened a probe JLO with the fastest response time (30 min) and highest fluorescence quantum yield (Ф = 0.731). The probe also has a large Stokes shift, which can reduce fluorescence self-absorption and background interference, and also has a high sensitivity, which is designed to accurately detect endogenous and exogenous H2O2 in living cells, which has great potential for biological applications.