Recent advances in fluorescent probes for lipid droplets.

Lipid droplets (LDs) have been known as a non-negligible cellular organelle for lipid storage and metabolism. Fluorescent probes for imaging LDs would be paramount for depicting their functions in cells. Although commercially available Nile Red and BODIPY 493/503 have been widely used for labelling LDs, they exhibit unsatisfactory specificity and spectroscopic properties. This feature article reviews the recent advances in organic fluorescent probes for imaging LDs. We first introduce the key points for probe design, including regulating hydrophobicity and enhancing fluorescence quantum yield in LDs. Then, we summarize the structural features and biological applications of some representative LD probes classified by their frameworks. In addition, the current challenges and future research trends for the fluorescent probes of LDs are discussed as well.