A Turn‐On Fluorescence Probe for Rapidly Sensing Exogenous and Endogenous Hydrogen Peroxide in Living Cells

Abstract Monitoring abnormal changes in hydrogen peroxide (H 2 O 2 ) levels in mammalian cells is essential to understanding its physicochemical functions in biological systems. Generally, H 2 O 2 fluorescent probes used for intracellular monitoring are limited to the long response time and low sensitivity. Herein, the 1,8‐naphthimide‐based fluorescent probe (NPB) with excellent photostability was confirmed to be an H 2 O 2 specific probe due to the oxidation of borate ester to phenol. Compared with previously reported molecular probes, NPB displayed improved performance in H 2 O 2 detection, such as excellent photostability, good anti‐interference, high selectivity, fast response (10 s), and low detection limit (15 nM). Furthermore, the most outstanding advantage of the as‐prepared NPB was mitochondrial‐targeting ability with a Pearson's colocalization coefficient of 0.91. Meanwhile, the probe NPB with excellent biocompatibility was successfully utilized for imaging exogenous and endogenous H 2 O 2 in living cells. The sensing mechanism of NPB to H 2 O 2 was further carefully demonstrated and proposed to involve the oxidation of borate to phenol by H₂O₂. We anticipated that the as‐prepared NPB should have broad application in chemical analysis and reveal the physiological function of H 2 O 2 in vivo.