Super-resolution imaging and real-time tracking lysosome in living cells by a fluorescent probe

Lysosomes function as important organelles within cells and their movement associates with diverse biological events, hence the real-time tracking of lysosomal movement is of great significance. However, since most lysosome fluorescent probes suffer from relatively unsatisfactory photostability, tracking lysosomal movement in real-time remains challenging. Here, we report that a naphthalimide-based fluorescent compound, namely NIMS, is a quite promising probe for lysosome imaging. The visualizing mechanism lies in the selective accumulation of NIMS in lysosomes via a protonation reaction, followed by the fluorescence enhancement due to the interactions of NIMS with proteins. Owing to its high selectivity and good photostability, NIMS was successfully applied to capture super-resolution fluorescence images of lysosomes. More importantly, real-time tracking of lysosome movement in a single living cell by NIMS was realized with a confocal laser scanning microscope. Surprisingly, even in normal culture conditions, around 2/3 of the captured lysosomes were observed to move within 5 min, indicative of the highly dynamic features of lysosomes. Thus, this probe may facilitate the understanding of the lysosome dynamics in physiological or pathological conditions.