Hypoxia-activated Probe for NIR Fluorescence and Photoacoustic Dual-mode Tumor Imaging

We rationally designed and synthesized a hypoxia-responsive probe TBTO featuring four diethylamino <i>N</i>-oxide groups that could undergo bioreduction in a hypoxic microenvironment, producing TBT with a typical D-A-D structure. It was demonstrated that TBT possesses NIR fluorescence emission and PA signal generation, benefiting from its both AIE property and a strong TICT effect. <i>In vitro</i> and <i>in vivo</i> assessments revealed the responsiveness of TBTO in a reductive environment and its NIR fluorescence and PA dual-mode imaging ability.