A Coumarin‐Based Fluorescent Probe for the Detection of Hypochlorite Ions and Its Applications in Test Paper and Cell Imaging

BODIPY-Based Fluorescent Probes for Selective Visualization of Endogenous Hypochlorous Acid in Living Cells via Triazolopyridine Formation

In this work, the two pyridylhydrazone-tethered BODIPY compounds (2 and 3) were synthesized. These compounds aimed to detect hypochlorous acid (HOCl) species via cyclic triazolopyridine formation. The open forms and the resulting cyclic forms of BODIPYs (2, 3, 4, and 5) were fully characterized by nuclear magnetic resonance, mass spectrometry, infrared spectroscopy, and single-crystal X-ray diffraction. These two probes can selectively detect HOCl through a fluorescence turn-on mechanism with the limit of detections of 0.21 µM and 0.77 µM for compounds 2 and 3, respectively. This fluorescence enhancement phenomenon could be the effect from C = N isomerization inhibition due to HOCl-triggered triazolopyridine formation. In cell imaging experiments, these compounds showed excellent biocompatibility toward RAW 264.7 murine live macrophage cells and greatly visualized endogenous HOCl in living cells stimulated with lipopolysaccharide.

Research Progress of Small Molecule Fluorescent Probes for Detecting Hypochlorite

Hypochlorous acid (HOCl) generates from the reaction between hydrogen peroxide and chloride ions via myeloperoxidase (MPO)-mediated in vivo. As very important reactive oxygen species (ROS), hypochlorous acid (HOCl)/hypochlorite (OCl⁻) play a crucial role in a variety of physiological and pathological processes. However, excessive or misplaced production of HOCl/OCl⁻ can cause variety of tissue damage and human diseases. Therefore, rapid, sensitive, and selective detection of OCl⁻ is very important. In recent years, the fluorescent probe method for detecting hypochlorous acid has been developed rapidly due to its simple operation, low toxicity, high sensitivity, and high selectivity. In this review, the progress of recently discovered fluorescent probes for the detection of hypochlorous acid was summarized with the aim to provide useful information for further design of better fluorescent probes.