A fluorescence sensor for nitroreductase detection in hypoxic cells and zebrafish

Nitroreductase (NTR) is a type of cytoplasmic enzyme that depends on flavin mononucleotide or flavin adenine dinucleotide, and that is widely present in tumor cells where it increases during hypoxia. NTR can effectively reduce aromatic nitro compounds to corresponding amino compounds, with the assistance of reduced nicotinamide adenine dinucleotide (NADH). In this study, a nitro-containing fluorescent turn-on probe, TP-NO, was synthesized and characterized. TP-NO exhibited a fast and selective response towards NTR (LOD = 1.96 ng/mL), and which reaction mechanism was proved through molecular docking. In addition, TP-NO has been successfully applied in imaging hypoxia levels in tumor cells, and zebrafish. This work provided a probe that can be applied to investigate NTR in biological systems.