Fluorescent probes based on multifunctional encapsulated perylene diimide dyes for imaging of lipid droplets in live cells

Due to their strong hydrophobicity and the aggregation-caused quenching effect, the application of perylene diimide ( PDI ) dyes in biological and medicinal fields lags far behind that of other dyes. Based on a multifunctional encapsulation strategy, we prepared isopropylphenyl sulfone encapsulated PDI dyes ( SFPDIs ). The four hydrophilic sulfone groups on the bay position of the PDIs not only effectively inhibit the fluorescence quenching caused by π-aggregation but also endow the SFPDIs with good live-cell permeability. The six lipophilic isopropylphenyl groups encapsulate PDI emitters and confer SFPDIs with excellent lipid droplet-targeting ability. Furthermore, the strong electron-withdrawing sulfone groups give the PDIs excellent anti-oxidation ability. A multifunctional encapsulation strategy confers perylene diimide dyes with high brightness, live-cell permeability, excellent anti-oxidation and lipid droplet-specific staining ability.