Development of a ratiometric fluorescent probe for selective detection and bioimaging of hydrogen peroxide in HeLa...

Because intracellular H₂O₂ levels vary dynamically and are involved in both redox signaling and oxidative stress linked to human health and disease, quantitative fluorescent detection of H₂O₂ is essential in living systems. In this work, a carbazole-based ratiometric fluorescent probe, KD-H₂O₂, was designed and synthesized for the selective detection of H₂O₂. Performance evaluation demonstrated that KD-H₂O₂ exhibited excellent sensing properties, including a broad pH tolerance range (pH 3.0-11.0), high detection sensitivity with a low limit of detection (LOD) of 2.74 μM, and favorable biocompatibility and low cytotoxicity. Notably, upon reaction with H₂O₂, the probe solution exhibited a distinct colour change that could be readily observed with the naked eye. Furthermore, bioimaging experiments demonstrated that KD-H₂O₂ enabled visualization of endogenous and exogenous H₂O₂ in HeLa cells, and it could detect exogenous H₂O₂ in zebrafish. Overall, the probe is a reliable tool for monitoring dynamic H₂O₂ changes in biological systems and has potential biomedical applications.