Long-term in-situ real-time fluorescence imaging of lipid droplets during cell ferroptosis process enabled by an epindolidione-based fluorescent probe

Abstract

Ferroptosis, as a new form regulation of cell death discovered recently, is triggered by an iron-dependent accumulation of lipid reactive oxygen species and thus closely associated with cellular lipid droplets (LDs). However, directly limited by the un-sufficient photostability and low LDs specificity of common fluorescent probes, visualization of LDs during ferroptosis process particular in a long-term, in-situ, and real-time manner is highly preferred but extremely challenge. To this end, here a new LDs fluorescent probe Lipi-EP featuring with outstanding photostability and high LDs specificity have been rationally developed based on the four-ring-fused epindolidione. Experimentally, the photostability and LDs specificity of this new probe are much higher than the representative LDs probe BODIPY and Nile Red. Consequently, time-lapse multicolor imaging and time-lapse three-dimensional imaging employed this new probe have been successfully conducted to in-situ real-time monitor the LDs change during ferroptosis process up to 6 h. The morphology changes of cellular organelles (LDs, mitochondria and nucleus) and the variations of space distribution of LDs have been impressively visualized. Moreover, the sizes and numbers of LDs have been also determined based on the imaging. This work providing abundant information of LDs would significantly promote the in-depth study of LDs during ferroptosis.