Probing mitochondrial peroxynitrite biogenesis by a N-morpholinoarylimine-based iridium(III) complex in drug-induced liver cells

Peroxynitrite (ONOO − ), a strong oxidizing agent, has an important function in the pathogenesis of various diseases, including cardiovascular, inflammatory and neurodegenerative diseases. Specifically, mitochondrial ONOO − exacerbates liver injury by driving oxidative/nitrative stress and mitochondrial dysfunction, ultimately triggering dual apoptotic-necrotic hepatocyte death pathways. ONOO − and its functions have been widely studied by fluorescence imaging probes, owing to their strong sensitivity, non-invasiveness, and real-time ability. However, existing probes are heavily constrained by interference from other reactive species. Herein, we describe a luminescent iridium(III) complex ( 1 ) with an N -morpholinoarylimine moiety as the recognition site for ONOO − for imaging mitochondrial ONOO − . The probe shows high luminescence response to ONOO − in aqueous buffer, with a luminescence enhancement of 27-fold at 200 μM ONOO − and a limit of detection (LOD) of 0.65 μM, as well as high selectivity over other reactive species. Furthermore, the probe can sense both exogenous and endogenous mitochondrial ONOO − . Further experiments demonstrated it could visualize endogenous ONOO − in 3D multicellular spheroids (MCTS) and unmask endogenous ONOO − production through an NADPH oxidase 4 (NOX-4)-mediated pathway in drug-induced liver cells. This work demonstrates the potential of this strategy for developing imaging tools for probing the pathological roles of subcellar ONOO − and diagnosing liver injury in the clinic. • N- morpholinoarylimine group is first used as peroxynitrite recognition unit. • The probe can image both endogenous and exogenous peroxynitrite in mitochondria. • The probe can track NOX-4-mediated peroxynitrite generation.