A distyrylbenzene-based fluorescent probe with high photostability and large Stokes shift for STED nanoscopy imaging of cellular lipid droplets

Directly limited by the availability of suitable organic fluorescent probes, the stimulated emission depletion (STED) nanoscopy imaging of cellular lipid droplets (LDs) is a highly challenge task. Herein, a sulfone-embedded distyrylbenzene derivative SO2-DSB has been reported as a novel LDs fluorescent probe suitable for STED nanoscopy imaging. This fluorescent probe exhibiting high photostability and large Stokes shift could be efficiently depleted while be not excited by the extremely strong STED lasers of 592 nm or 660 nm. Consequently, STED nanoscopy imaging of LDs employed with this fluorescent probe has achieved high resolutions of 73 nm and 84 nm under 592 nm and 660 nm STED lasers, respectively. Notably, these resolutions are significantly higher than the common confocal images (resolutions of about 250 nm) and represent one of the leading results of the nanoscopy imaging of LDs so far, highlight the ability of this fluorescent probe in STED nanoscopy. In addition, the general ability of this fluorescent probe in confocal microscopy has also been demonstrated by 3D imaging and multicolor imaging.