Selective turn-on near-infrared fluorescence probe for hypoxic tumor cell imaging

Hypoxia is a typical feature of solid tumors. To detect hypoxic tumor cells, we designed new selective turn-on probes by conjugating (1-methyl-2-nitro-1H-imidazol-5-yl)methanol to the near-infrared fluorescence probe DCPO through an ether linkage and bis-carbamate linkage specifically. The proposed activation mechanism was demonstrated through the nitroreductase and cytochrome P450 assays in vitro. However, two probes revealed different hypoxia selectivities when evaluated on H460, HeLa and A549 cell lines. The hypoxia selectivity of IOD was higher than that of IND. The probe IOD (containing the ether linkage) was considered to be a promising hypoxia-selective fluorescent probe.