Lipid droplet-targeting optical biosensors: Design strategies and applications

Lipid droplets (LDs) are known as an essential cellular organelle for lipid storage and metabolism. Fluorescent probes for imaging LDs are vital for studying the role of LDs in cells, and therapeutics targeting LDs may contribute to the fight against diseases induced by abnormal lipid metabolism. Although some commercial dyes (e.g., Nile Red and BODIPY 493/503) have been widely used for LD labeling, they exhibit unsatisfactory spectroscopic properties and specificity. This review mainly discusses LD-targeting fluorescent probes classified by their applications in imaging and theranostics. We also introduce the preparation processes and structural characteristics of these probes, as well as various photophysical mechanisms/phenomena utilized in their design. The current limitations and future research directions in this field are also proposed. We hope that this review will have implications for the future development of LD-targeting fluorescent probes for various practical applications.