Luminescence imaging-guided triple-collaboratively enhanced photodynamic therapy by bioresponsive lanthanide-based nanomedicine.

Photodynamic therapy (PDT) provides a novel sight for non-invasive tumor ablation, which, however, is still limited by low converting efficiency and short life-time of produced singlet oxygen. In this work, a bioresponsive lanthanide-based nanomedicine, FeOOH-coated and toluidine blue (TB)-loaded NaLuF4:Yb,Er,Tm@NaLuF4, is constructed for tumor microenvironment-activated photodynamic therapy with triple-collaborative enhancing strategy. In response to intratumoral reducibility and acidity, coated FeOOH decomposes, eliminating reduced glutathione (GSH) and up-regulating intratumoral oxidative stress to enhance PDT. Besides, Fe2+ is also released from this redox process, which can improve intratumoral dissolved O2 for PDT by catalytic decomposition of H2O2. Lastly, quenched upconversion luminescence of lanthanide-doped nanoparticles also recovers, which allows more efficient energy transfer to TB and hence improves PDT efficiency. By the above triple-collaborative strategy, highly efficient photodynamic tumor ablation is performed in vivo. This work proposes a rigorous method to elevate photodynamic therapeutic efficiency.