Nitroreductase (NTR) belongs to a class of flavin mononucleotide-dependent and flavin adenine dinucleotide-dependent cytoplasmic enzymes; its contents in tumor cells increase during hypoxia. The development of fluorescent probes for detection of NTR activity is of great significance for the study of the state of hypoxia in living organisms. In this paper, a red-emitting fluorescence turn-on probe EBI-NO₂ was synthesized using a one-step method. The fluorescence of the probe was enhanced by 60 folds in the presence of NTR. The probe also had high selectivity towards NTR, and its detection limit was as low as 1 ng/mL. The reaction mechanism was verified using MS, molecular docking and theoretical calculations. In addition, it was successfully applied in real-time monitoring of NTR produced during growth of Escherichia coli (BL21) and in visualization of NTR in oral cancer cells (Cal-27) under hypoxia. This work provides a new imaging tool that can be applied to investigate the physiological and pathological changes in hypoxia oral cells.

硝基还原酶（NTR）属于一类黄素单核苷酸依赖性和黄素腺嘌呤二核苷酸依赖性细胞质酶。缺氧时其在肿瘤细胞中的含量增加。用于检测NTR活性的荧光探针的开发对研究活生物体缺氧状态具有重要意义。本文采用一步法合成了发红光的荧光探针EBI-NO ₂。在NTR存在下，探针的荧光增强了60倍。该探针对NTR的选择性也很高，其检出限低至1 ng / mL。使用质谱，分子对接和理论计算验证了反应机理。此外，它还成功地用于实时监测生长期间产生的NTR。大肠杆菌（BL21）和低氧下口腔癌细胞（Cal-27）中的NTR可视化。这项工作提供了一种新的成像工具，可用于研究缺氧口腔细胞的生理和病理变化。