Sulfur-based fluorescent probes for HOCl: Mechanisms, design, and applications

[Display omitted] •Reaction mechanisms of various types of sulfur-based fluorescent probes with HOCl.•The advantages and disadvantages of sulfur-based fluorescent probes for HOCl.•The applications of sulfur-based fluorescent probes for HOCl. Hypochlorous acid (HOCl) is an endogenously produced reactive oxygen species (ROS), which acts as a protector against microbes. However, its aberrant production is implicated in various oxidative-stress related pathophysiological processes, such as cardiovascular disorders, arthritis, and neurodegenerative diseases. Therefore, the direct, rapid, sensitive, and selective detection of endogenous HOCl in living systems is of essential importance for better understanding the HOCl-involved chemical biology. In the last two decades, sulfur-based fluorescent probes for HOCl have been widely designed and they usually show rapid reaction rate, high selectivity and excellent sensitivity. This review summarized the advances that have been made in the development of sulfur-based fluorescent probes for HOCl, and their reaction mechanisms were emphatically discussed. Lastly, the achievements, challenges, and perspectives in this field were outlooked.