Intriguing "chameleon" fluorescent bioprobes for the visualization of lipid droplet-lysosome interplay.

The interplay of lipid droplets (LDs) and lysosome plays an important role in cell metabolism, and the visualization of this process can provide useful information of organelle communication and function. However, fluorescent bioprobes based on organic fluorophores that can respond to LD-lysosome interplay are much rare. Herein, fluorescent bioprobes with high photostability, excellent biocompatibility and intracellular polarity sensitivity are achieved by encapsulating a new red fluorogenic molecule TPA-BTTDO within polymeric matrix (DSPE-PEG). They can sequentially localize in lysosome and LDs with red and cyan emissions, respectively. By monitoring the emission color change, the interesting dynamic processes of the probes escaping from lysosome and then enriching in LDs, and finally returning to lysosome after LDs consumption are visualized. In addition, the tracing of dynamic movement and consumption of LDs is realized by the probes with a high signal-to-noise ratio. The unique labeling behaviors and distinguished dual emissions of the probes in LDs and lysosome make them promising agents for fluorescence visualization studies of LD-lysosome related bioprocess and metabolism diseases.