A Cascade Activation Probe with Double-Enhanced Near-Infrared Imaging for Monitoring Peroxynitrite Fluctuations in Vivo.

Monitoring peroxynitrite (ONOO) fluctuations is particularly important for assessing pathological progression and oxidative damage due to their crucial role in maintaining the redox balance of organisms. However, due to the lack of efficient tools for differentially monitoring ONOO fluctuations at different concentration ranges in vivo, the precise detection of endogenous ONOO fluctuations under pathological conditions in living systems remains challenging. Herein, we rationally designed a double-enhanced emission cascade activatable near-infrared (NIR) fluorescent probe () for the measurement of ONOO, which consists of a borate ester response group and a malononitrile hemicyanine fluorophore.