NIR-H2O2 is a cell-permeable near-infrared (NIR) fluorescent turn-on sensor that exhibits a significant turn-on NIR fluorescence signal in response to H2O2 upon excitation in the NIR region.

NIR-H2O2 is highly selective to H2O2 over other typical ROS and bio-relevant species. HeLa cells incubated with NIR-H2O2 (5 μM, 30 min, 37 °C) exhibit minimal fluorescence, but show strong fluorescence upon H2O2 treatment. Similarly, RAW264.7 macrophages loaded with NIR-H2O2 (1 μM) display almost no fluorescence, but when co-incubated with PMA (3.0 μg/mL), show significant red emission. NIR-H2O2 effectively enables fluorescent imaging of endogenous H2O2 in living RAW264.7 macrophages.

In an acute inflammation model induced by lipopolysaccharide (LPS), in vivo hydrogen peroxide (H2O2) production was generated by activated macrophages and neutrophils. Mice treated with both LPS and near-infrared-responsive H2O2 (NIR-H2O2) displayed significantly higher fluorescence readouts than those untreated or treated solely with NIR-H2O2. Specifically, fluorescence intensity in mice administrated with LPS and NIR-H2O2 was approximately 10- and 20-fold greater compared to mice treated with saline and the sensor, and mice treated with saline alone, respectively.