NIR-driven water splitting by layered bismuth oxyhalide sheets for effective photodynamic therapy

Two major issues of finding the appropriate photosensitizer and raising the penetration depth of irradiation light exist in further developing of photodynamic therapy (PDT). The excited ultraviolet/visible (UV/vis) irradiation light has a relatively shallow depth of penetration and UV light itself may have sufficient energy to damage normal tissues; these are substantial limitations to successful cancer therapy. Herein, we for the first time report a novel multifunctional nanoplatform for a single 980 nm near-infrared (NIR) light-triggered PDT based on NaGdF₄:Yb,Tm@NaGdF₄ upconversion nanoparticles (UCNPs) integrated with bismuth oxyhalide (BiOCl) sheets, designated as UCNPs@BiOCl. And UCNPs@BiOCl was fabricated by a convenient, efficient, green, and inexpensive method. Excitingly, layered bismuth oxyhalide materials possess a high photocatalytic performance, unique layered structures and wide light response to a broad wavelength range of ultraviolet to visible light. And the loaded UCNPs can convert NIR light into UV/vis region emissions, which drives the pure water splitting of BiOCl sheets to produce plenty of reactive oxygen species (ROS) to damage tumor cells. The excellent antitumor efficiency of the complex has been evidently attested by comparing experimental results. Our work may make a contribution to the wide application of BiOCl-based materials in biomedicine.