A Highly Sensitive and Selective Near-Infrared Fluorescent Probe for Imaging Peroxynitrite in Living Cells and Drug-Induced Liver Injury Mice

Drug-induced liver injury (DILI) is a major clinical issue associated with the majority of commercial drugs. During DILI, the peroxynitrite (ONOO–) level is upregulated in the liver. However, traditional methods are unable to timely monitor the dynamic changes of the ONOO– level during DILI in vivo. Therefore, ONOO–-activated near-infrared (NIR) fluorescent probes with high sensitivity and selectivity are key to the early diagnosis of DILI in situ. Herein, we report a novel ONOO–-responsive NIR fluorescent probe, QCy7-DP, which incorporates a donor-dual-acceptor π-electron cyanine skeleton with diphenyl phosphinate. The ONOO–-mediated highly selective hydrolytic cleavage via an addition-elimination pathway of diphenyl phosphinate produced the deprotonated form of QCy7 in physiological conditions with a distinctive extended conjugated π-electron system and ∼200-fold enhancement in NIR fluorescence emission at 710 nm. Moreover, the probe QCy7-DP was successfully used for the imaging of the endogenous and exogenous ONOO– concentration changes in living cells. Importantly, in vivo fluorescence imaging tests demonstrated that the probe can effectively detect the endogenous generation of ONOO– in an acetaminophen (APAP)-induced liver injury mouse model. This study provides insight into the design of highly selective NIR fluorescent probes suitable for spatiotemporal monitoring of ONOO– under different pathological conditions.