A novel nitro-substituted benzothiadiazole as fluorescent probe for tumor cells under hypoxic condition

A new compound, 4,7-bis(4-dodecylthiophen-2-yl)-5,6-dinitrobenzo[c][1,2,5]thiadiazole (BTTD-NO2), was synthesized in this paper. The fluorescence of BTTD-NO2 was quenched by its two nitro groups. However, the tumors cells were stained with strong red fluorescence after reduction of BTTD-NO2 via transformation of its nitro groups to amino groups under hypoxic condition. The results suggested that BTTD-NO2 had the potential as a superior fluorescent probe for labeling the hypoxic tumor cells specially.