An electroneutral fluorescent probe for visualization of lipid droplets polarity heterogeneity and NAFLD detection

Lipid droplets (LDs), omnipresent organelles in nearly all eukaryotic cells, have garnered significant attention in cell biology. Alterations in LD polarity not only signify cellular carcinogenesis but also correlate closely with the severity of nonalcoholic fatty liver disease (NAFLD). Despite their importance, the lack of suitable detection tools has limited research and clinical applications in this area. In this study, we develop LD-PL, an electroneutral fluorescent probe to visualize LDs polarity heterogeneity. Interestingly, LD-PL exhibits exceptional sensitivity to LD polarity variations and can distinguish normal cells from cancer cells. Crucially, LD-PL maps a spatially organized polarity landscape by ratiometric imaging in LDs, and confirms LD structural polarity (high-polarity surface and low-polarity core). Importantly, LD-PL can distinguish NAFLD tissues with different degrees of severity by detecting LD polarity, with polarity E_T(30) values ranging from 58.5 to 51.1. This work provides a powerful tool for studying the heterogeneity of LD polarity and quantitative detection of NAFLD staging progression.