A highly sensitive rapid-response fluorescent probe for specifically tracking endogenous labile Fe2+ in living cells and zebrafish

Iron plays an essential role in the chemical transformation of cells via the transition of multiple oxidation states of iron. Misregulation of iron may lead to the disorder of reactive oxygen species (ROS) catalyzed by iron, which is associated with diverse diseases. Therefore, the monitoring of labile iron in vivo is crucial for revealing its diverse functions in the biosystems. In this work, a novel “off-on” fluorescent probe NT-Fe was designed to detect ferrous ion (Fe2+) in both aqueous solutions and biological systems, based on the reduction of nitroxides to hydroxylamine. Probe NT-Fe manifested highly selective and sensitive detection (DL = 89 nM) of Fe2+. In addition, probe NT-Fe can detect Fe2+ within 50 s, which is conducive to real-time detection of labile iron in the biological system. Moreover, the intracellular Fe2+ can be tracked with probe NT-Fe in living cells effectively. Most of all, as far as we know, probe NT-Fe has been used for the first time to monitor Fe2+ in zebrafish.