A Cresyl Violet-Based Fluorescent Off-On Probe for the Detection and Imaging of Hypoxia and Nitroreductase in Living Organisms

A new cresyl violet‐based fluorescent off–on probe has been developed through a one‐step synthesis for the detection of nitroreductase (NTR) and hypoxia. The detection mechanism is based on the NTR‐catalyzed reduction of the probe to cresyl violet, accompanied with a large fluorescence enhancement at a long wavelength of 625 nm. The probe can detect NTR in aqueous solution with high selectivity and sensitivity, and the detection limit is 1 ng mL−1 NTR. Most importantly, the probe has been successfully used to image not only NTR and hypoxia in living cells, but also the distribution of NTR in zebrafish in vivo. To probe or not to probe: A new cresyl violet‐based fluorescent off–on probe has been developed for the detection of nitroreductase (NTR) and hypoxia. The probe displays high selectivity and sensitivity, and has been used to detect NTR and hypoxia in living cells and the distribution of NTR in zebrafish in vivo.