An AIE-active triphenylethylene probe for ultrasensitive detection of peroxynitrite and imaging in living cells

Accurate detection of mitochondrial peroxynitrite (ONOO^-) is crucial for elucidating its roles in physiological and pathological processes. However, its detection remains challenging due to its short half-life, low concentration, and interference from reactive species. To address this, we developed an activatable AIE fluorescent probe, NN-3, which achieves high selectivity through an addition-elimination reaction involving its diphenylphosphinyl group. Upon ONOO^--mediated cleavage of the phosphoester bond, the probe exhibits a significant fluorescence enhancement of up to 3062-fold. NN-3 provides a quantitative response to ONOO^- over a wide concentration range (5-50 μM), with an ultra-low detection limit of 7.0 nM and rapid response characteristics, while maintaining excellent resistance to biological interference. Furthermore, the probe successfully imaged dynamic ONOO^- concentrations in the mitochondria of living cells, exhibiting excellent cell membrane permeability and negligible cytotoxicity.