Specific Fluorescence Probes for Lipid Droplets Based on Simple AIEgens.

Lipid droplets (LDs), as dynamic complex organelles, are involved in various physiological processes, and their numbers and activity are related to many diseases, even cancer. Hence, locating and concentration monitoring of LDs are very important to scientific bioresearch and health care. In this work, we prepared two simple luminogens (FAS and DPAS) via very facile synthetic procedures and purification. They feature aggregation-induced emission and excited state intramolecular proton transfer characteristics. They exhibit large Stokes shifts and bright orange and yellow emissions in the aggregated state, and the emissions can be reversibly turned "off" and "on" for many cycles by controlling buffer pH values. Both FAS and DPAS are cytocompatible and can selectively accumulate in and light up the LDs in living cells with superior resolution and high contrast. They also outperform the commercial LD probes in terms of photostability. Combining the advantages of high LD-specificity, good biocompatibility, surperb photostability, and low preparation cost, FAS and DPAS may become powerful tools to the study on LDs-related intracellular activities, such as LDs-based pathology and pharmacology.