Versatile Fluorescent Probes for Imaging the Superoxide Anion in Living Cells and In Vivo

The superoxide anion (O₂^.- ) is widely engaged in the regulation of cell functions and is thereby intimately associated with the onset and progression of many diseases. To ascertain the pathological roles of O₂^.- in related diseases, developing effective methods for monitoring O₂^.- in biological systems is essential. Fluorescence imaging is a powerful tool for monitoring bioactive molecules in cells and in vivo owing to its high sensitivity and high temporal-spatial resolution. Therefore, increasing numbers of fluorescent imaging probes have been constructed to monitor O₂^.- inside live cells and small animals. In this minireview, we summarize the methods for design and application of O₂^.- -responsive fluorescent probes. Moreover, we present the challenges for detecting O₂^.- and suggestions for constructing new fluorescent probes that can indicate the production sites and concentration changes in O₂^.- as well as O₂^.- -associated active molecules in living cells and in vivo.