Long-Wavelength Emitting Fluorescent Probe for Real-Time Peroxynitrite Imaging in Living Cells

Peroxynitrite (ONOO^-), a highly reactive nitrogen species with potent oxidative capacity, plays dual roles in cellular signaling and disease pathogenesis. To address the limitations of existing ONOO^- probes-particularly poor aqueous solubility and inadequate emission wavelengths-we developed P₃₀, a novel water-soluble fluorescent probe based on a rigid molecular scaffolding. P₃₀ selectively detects ONOO^- through azo-bond oxygenolysis, triggering rapid (< 10 s), sensitive (LOD = 0.38 µM), and long-wavelength fluorescence emission (λ_em = 612 nm). Crucially, P₃₀ enables real-time visualization of both exogenous and endogenous ONOO^- in live cells, demonstrating its utility for interrogating ONOO^- dynamics in biological systems. These attributes position P₃₀ as a robust tool for studying ONOO^--associated pathophysiological processes.