BODIPY-based Fluorescent Indicators for Lipid Droplets

Lipid droplets are essential for cellular lipid storage, playing critical roles in cellular lipid metabolism. Although lipid droplets have drawn intense research in recent years, much remains to be uncovered about the roles of this organelle in biology. Lipid droplet indicators exhibiting large Stokes shifts and improved brightness are therefore in demand. We report two asymmetric BODIPY derivatives, BoL1 and BoL2 bearing a benzothiazole group at the 6-position, which led to bathochromic shifts of 62 nm for BoL1 and 37 nm for BoL2 in fluorescence emission when compared to the reference molecules without the benzothiazole group. The incorporation of the benzothiazole moiety also resulted in a large Stokes shift of 40 nm. BoL1 and BoL2 have been demonstrated to operate as lipid droplet indicators in both confocal and STED imaging. BoL2 showed particularly good cellular retention and was further applied to explore the impact of cellular starvation on the trafficking of lipid droplets.