Mitochondria-Targeted Fluorescent Probe for Imaging Hydrogen Peroxide in Living Cells

Hydrogen peroxide (H₂O₂), as a type of reactive oxygen species (ROS), can be endogenously produced from the mitochondrial electron transport chain in aerobic respiration and plays important roles in several physiological processes. However, the design and synthesis of fluorescent probes, which can detect mitochondrial H₂O₂ in living cells, still remain rare. Herein, we report the preparation of a novel cationic probe <b>1</b> (<b>Mito-H</b>_<b>2</b><b>O</b>_<b>2</b>), which targets the mitochondria in living cells and is sensitive to the presence of H₂O₂. The probe <b>Mito-H</b>_<b>2</b><b>O</b>_<b>2</b> displays desired properties such as high specificity, “Turn-On” fluorescence response with suitable sensitivity, appreciable water solubility, and rapid response time (within 5 min). The sensing mechanism was confirmed by high-resolution mass spectroscopy analysis, and the mechanism of “Turn-On” fluorescent response was also determined using a density functional theory (DFT) calculation method. Moreover, as a biocompatible molecule, the probe <b>Mito-H</b>_<b>2</b><b>O</b>_<b>2</b> has been successfully applied for the detection of the intrinsically generated intracellular H₂O₂ in living cells, and the fluorescence colocalization studies indicate that the probe localizes solely in the mitochondria of HeLa cells