Investigating Lysosomal Reactive Sulphur Species with Small Molecular Fluorescent Probes

Reactive sulphur species (RSS) play a vital role in cellular redox homeostasis and signal transduction. The lysosome is a vital organelle in eukaryotic cells involved in phagocytosis, digestion and degradation of proteins or damaged organelles, repair of cell membrane and energy metabolism. Lysosomal RSS are closely associated with normal functions of the lysosome, and abnormal RSS homeostasis may lead to lysosomal dysfunction and some serious diseases. Thus, real-time visualization of lysosomal RSS is of great significance. Due to the prominent advantages of fluorescence imaging technology, many small molecular fluorescent probes for detecting lysosomal RSS have been developed. Herein, we have systematically summarized the versatile small molecular and lysosome-targetable fluorescent probes available for detecting RSS, including their chemical structures, response mechanisms and bioapplications. In addition, we have highlighted the current status, challenges and developmental prospects for RSS-responsive small molecular fluorescent probes. We sincerely hope that this review can instruct researchers interested in constructing new fluorescent probes for RSS and draw attention toward the significance of lysosomal RSS.