A novel fluorescent turn-on probe for highly selective detection of nitroreductase in tumor cells

The expression level of nitroreductase (NTR) is directly associated with cellular hypoxia states, which plays an important role in cancer invasion, metastasis, and resistance to treatment. Therefore, developing a facile and effective method for NTR detection is of great importance for improving anticancer treatment efficacies. To date, fluorescence method has received extensive attention for NTR detection due to its non-invasion, high sensitivity, and high spatial-temporal resolution features. However, most of fluorescent probes suffered from sophisticated systhesis procedure and poor biocompatibility, which would severely limit their practical applications especially for bioimaging. Herein, we repoted a novel chalcone-based fluorescence probe with simple preparation procedure and excellent biocompatibility for detection of NTR. The probe exhibits a highly selective fluorescence response towards NTR and the detection limit reaches 27 ng/mL. The specific fluorescence response can be ascribed to the NTR-catalyzed nitrobenzyl reduction mechanism, which has been verified by using fluorescence spectra, fluorescence lifetime, mass spectra, and inhibition experiments. Notably, this method successfully achieves hypoxia imaging in tumor cells, providing a useful tool for hypoxia pre-diagnosis.