Near-infrared fluorescence probe for hydrogen peroxide detection: design, synthesis, and application in living systems.

Using fluorescent probes to detect endogenous hydrogen peroxide, which is associated with many diseases in the human body, remains an essential technique. Cyanine fluorochromes are a class of dyes that have attracted much attention and are widely used in the synthesis of fluorescent probes. In this article, a novel near-infrared (NIR) fluorescence probe for the detection of hydrogen peroxide was constructed and successfully applied to imaging endogenous hydrogen peroxide in vivo. Notably, probe 1 was designed by connecting 4-(bromomethyl)benzeneboronic acid pinacol ester as the sensing unit to the IR-780 hemicyanine skeleton, which exhibits excellent properties like NIR fluorescence emission over 700 nm. Probe 1 has satisfactory sensitivity to hydrogen peroxide with a low detection limit of 0.14 μM (S/N = 3), attributed to a responding mechanism that leads to the oxidation of phenylboronic acid pinacol ester and thereby releases fluorophore 2. Moreover, probe 1 displays excellent selectivity towards hydrogen peroxide over other substances. Taking advantage of these properties, the probe proved to be cell-permeable. Based on the results of N-acetylcysteine and rotenone together, probe 1 is capable of clearly visualizing endogenously produced hydrogen peroxide in living HepG2 cells and mice. The superior performance of the probe, as a reliable chemical tool, makes it of great potential application for exploring the role played by hydrogen peroxide in biological systems.