Visualizing hydrogen peroxide in Parkinson's disease models via a ratiometric NIR fluorogenic probe

Parkinson's disease (PD) is a neurological disorder which will significantly overwhelm the life for the patient. Numerous studies have proved that hydrogen peroxide plays an important role in the pathogenesis of PD. To detect hydrogen peroxide in PD in live, here we report the design and synthesis of a new ratiometric and NIR fluorescence probe (NIR-HP1) for hydrogen peroxide, utilizing an excited state intramolecular proton transfer strategy to control the fluorescence. NIR-HP1 showed a highly selective ratiometric response to hydrogen peroxide over other reactive oxygen/nitrogen species, biothiols and various ions in aqueous solution at physiological pH. The observed pseudo-first-order rate constant for the reaction of NIR-HP1 with hydrogen peroxide was calculated to be 0.042 s⁻¹. The detection limit of this sensor for hydrogen peroxide was 0.27 μM. Moreover, NIR-HP1 worked well in living systems for hydrogen peroxide sensing as displayed by confocal fluorescence microscopy imaging, indicating potential application in PD study.