Ferric Hydroxide-Modified Upconversion Nanoparticles for 808 nm NIR-Triggered Synergetic Tumor Therapy with Hypoxia Modulation.

The efficacy of dynamic therapy for solid tumors suffers daunting challenges induced by tumor hypoxia. Herein, we report a biocompatible nanosystem containing Fe(OH)3-modified upconversion nanoparticles (UCNPs) for promoting synergetic chemo- and photodynamic therapy with the modulation of tumor hypoxia. In this system, UCNPs convert 808 nm near-infrared excitation to visible photon energy, which stimulates chlorin-e6 photosensitizers to generate toxic reactive oxygen species (ROS) by consumption of dissolved oxygen in cancer cells. Importantly, we employ Fe(OH)3 compounds to enable continuous oxygen generation in cancer cells and, meanwhile, induce extra ROS formation through the Fenton-like reaction. The system consequently improves the tumor treatment efficacy in vitro and in vivo. This study puts forward a novel combinatorial therapeutic platform for tumor microenvironment modulation and enhanced cancer therapy.