A simple mitochondria-immobilized fluorescent probe for the detection of hydrogen peroxide

Hydrogen peroxide (H₂O₂), as one of reactive oxygen species (ROS) widely present in the human body, is involved in a variety of physiological activities. Many human diseases are associated with abnormal levels of H₂O₂ in the body. Mitochondria are the main organelles producing H₂O₂ in the human body, and monitoring the level of H₂O₂ in mitochondria can help to deepen the understanding of the detailed functions of H₂O₂ in physiological activities. However, due to the highly dynamic nature of the cells, real-time quantitative monitoring of H₂O₂ levels in mitochondria remains an ongoing challenge. Herein, a novel highly immobilized mitochondria-targeting fluorescent probe (QHCl) for detection of H₂O₂ was reasonably constructed based on quinolinium dye containing benzyl chloride moiety. Spectral experimental results demonstrated QHCl possessed outstanding selectivity toward H₂O₂ (λ_ex/em = 380/513 nm). In addition, QHCl can quantitatively detect H₂O₂ in the concentration range of 0-20 μM with excellent sensitivity (LOD = 0.58 μM) under the PBS buffer solution (10 mM, pH = 7.4). Finally, bioimaging experiments demonstrated that the probe QHCl was able to be used for accurately detecting both endogenous and exogenous H₂O₂ in the mitochondria of living cells and zebrafish by its unique mitochondrial immobilization.