A highly sensitive NIR fluorescence probe for hypoxia imaging in cells and ulcerative colitis

Ulcerative colitis, a kind of inflammatory bowel disease (IBD), is caused by dysregulated immune response of intestinal bacteria. This chronic disorder can lead to a deficiency of O₂ (hypoxia) in the colon microenvironment. Nitroreductase (NTR) is a highly expressed endogenous enzyme under hypoxia, so the detection of NTR can provide diagnostic information about ulcerative colitis. Herein, an ultrasensitive NTR-triggered fluorescence probe (WS-1-NO₂) is developed for hypoxia imaging in ulcerative colitis. The probe shows a significant fluorescence enhancement (45-fold) after reacting with NTR, with an extremely low detection limit of 0.096 ng/mL. Furthermore, we apply it for fluorescence imaging of hypoxia in living cells, tumors and dextran sulphate sodium (DSS)-induced ulcerative colitis mouse models. We believe that the probe may be investigated as an effective potential tool for gaining insight into the hypoxia-relevant diseases, such as cancer and ulcerative colitis.