A ratiometric fluorescent probe monitoring lipid peroxidation within lipid droplets in foam cells

Lipid peroxidation (LPO) in foam cells is crucial for regulating atherosclerosis progression. It correlates with lipid uptake and the state of lipid droplets. In this study, we report a lipid droplet‐targeted fluorescent LPO probe, Ld‐LPO. It selectively responds to LPO, resulting in a significant fluorescence shift from 590 to 525 nm, enabling a ratiometric imaging of LPO in lipid droplets. Ld‐LPO traces lipid droplets in foam cells, revealing a correlation between LPO and lysosomal engulfment. We found that lipid droplets engulfed by lysosomes exhibit higher LPO, attributed to low‐density lipoprotein accumulation in lysosomes. Furthermore, Ld‐LPO is compatible with dual‐color flow cytometry, facilitating high‐throughput analysis of LPO in foam cells.