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.