An endoplasmic reticulum-targeted fluorescent probe for peroxynitrite visualization in drug-induced liver injury and hepatic ischemia-reperfusion injury

Drug-induced liver injury (DILI) and hepatic ischemia-reperfusion injury (HIRI) are closely associated with aberrant accumulation of peroxynitrite (ONOO^-) in the endoplasmic reticulum (ER). In this work, we designed and synthesized ER-ND, an ER-targeted turn-on fluorescent probe for the detection of ONOO^-. This probe is composed of three key functional components: a 1,8-naphthalimide-based fluorophore, a 3,5-bis(trifluoromethyl)benzyl group serving as an ER-anchoring moiety, and a 4-(dimethylamino)phenoxy group acting as a responsive unit. ER-ND demonstrates a rapid response to ONOO^-, along with high sensitivity and selectivity, which are achieved through the modulation of intramolecular charge transfer (ICT). Additionally, it exhibits excellent photostability, low cytotoxicity, and precise localization within the ER. The probe can be effectively employed for the real-time visualization of dynamic changes of ONOO^- in both cellular and murine models of DILI and HIRI in real time. This capability allows for an accurate assessment of the severity of liver injury and evaluation of the therapeutic efficacy of hepatoprotective agents. Moreover, by utilizing ER-ND, we uncovered a direct link between ONOO^- overload and ferroptosis during the progression of DILI. In conclusion, ER-ND offers a versatile molecular platform for imaging ER-associated ONOO^-. It holds significant promise as a tool for the early diagnosis, pathophysiological investigation, and drug screening in the context of liver injury.