Activity-Based Imaging of Lipid Environments Targeted by Peroxynitrite in Biomimetic Vesicles and Live Cells

Peroxynitrite (ONOO−), a redox-active species generated under nitrosative stress conditions, can promote oxidative damage of lipids. Herein, we report the development and multifaceted utilization of a novel, activity-based phospholipid probe, PLP-ONOO–, for imaging lipid environments that are targeted by ONOO− in biomimetic and biological systems. Using PLP-ONOO– and the natural lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, we built synthetic protocell membranes in the form of giant vesicles (GVs). These GVs responded to ONOO− by lighting up and displayed excellent selectivity against other redox-active species, introducing an unprecedented function to biomimetic membrane architectures. Live HeLa cells containing PLP-ONOO– were investigated under cellular nitrosative stress induced by either external administration of peroxynitrite or endogenous stimulation with interferon-γ / lipopolysaccharide / phorbol myristate acetate. Both conditions enhanced the coumarin fluorescence within cells, providing insight into intracellular lipid environments potentially prone to peroxynitrite-mediated oxidative damage. This work offers a chemical reactivity-dependent function for synthetic vesicles and opens a possibility for investigating nitrosative stress at subcellular levels.