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Designing luminescence lifetime sensors in the second near-infrared (NIR-II) window is a great challenge due to the difficult structural construction. Here, we report a tumor redox responsive and easily synthesized material, amorphous manganese oxide (MnOx ) with indirect band gap of 1.02 eV, as an energy acceptor to build a luminescence resonance energy transfer (LRET) toolbox for universally regulating NIR-I to NIR-II luminescence lifetimes of lanthanide nanoparticles, in which energy transfer is based on matched energy gap instead of conventional overlapped spectra. We further utilize ytterbium (Yb3+ )-doped YbNP@MnOx as an NIR-II luminescence lifetime sensor to realize in vitro quantitative redox visualization with relative errors under 5 % in samples covered with mouse skin. Furthermore, HepG2 cells and tumors with high redox state have been accurately distinguished by NIR-II luminescence lifetime imaging. The quantified intracellular and intratumor glutathione (GSH) levels are highly consistent with the commercial kit results, illustrating the reliable redox visualization ability in biological tissue.
Zhao et al. (Fri,) studied this question.