An activatable biphotonic lanthanide probe for detection of nitroreductase in live bacteria and cancer cells

imaging. The terbium-based luminescent probe is non-fluorescent in its inactive state but can be selectively activated by nitroreductase, leading to the release of the sensitizing antenna that facilitates energy transfer to the lanthanide center, resulting in an intense luminescence signal. We show the probe’s capability to selectively sense nitroreductase not only in bacterial lysates but also in live bacteria of the ESKAPE family. Moreover, the probe effectively detects mammalian nitroreductase in prostate cancer cells, which is expressed under mild hypoxic conditions. The results obtained set the stage for a new generation of activatable lanthanoid-based probes that are suitable for two-photon excitation.