Advances in the Development of Water-Soluble Fluorogenic Probes for Bioimaging of Hypochlorite/Hypochlorous Acid in Cells and Organisms

This mini-review summarizes the development of intracellular fluorogenic probes for biological investigations of hypochlorous acid/hypochlorite (HOCl/OCl-) in living cells and tissues. Monitoring the formation or effects of reactive oxygen species (ROS) inside living systems is critical in determining their roles in human physiology. HOCl/OCl- is considered as an important member of the nonradical ROS family for its decisive microbicidal action in the innate immune system. Even though HOCl/OCl- plays a defensive role in human health, abnormal or overexpression may have detrimental effects on the host physiology leading to many diseases, including neurodegeneration and cancer. In recent years, progress in the development of fluorescent imaging probes for observing HOCl/OCl- levels in live cells and tissues has been made. Despite considerable advancement, challenges still exist in areas like working solvent/media, pH, response time, buffer selection, emission region, and others. In addition, this account aims to discuss the design strategies and sensing mechanisms of the representative fluorogenic probes for bioimaging of HOCl/OCl-, endogenously and exogenously. Herein, we also have tried to provide the future direction to develop HOCl/OCl- specific probes for disease diagnosis with particular attention to the requirement of the recognition group, solvent, and buffer media, which will be beneficial for those working in the domain of biomedical research.