pH-Activated Ce-Doped Molybdenum Oxide Nanoclusters for Tumor Microenvironment Responsive Photothermal and Chemodynamic Therapy

Molybdenum-based nanomaterials have shown promise foranticancertreatment due to their strong photothermal and redox-activated capabilities.Herein, we have fabricated cerium-doped MoO (x) (Ce-MoOv) with tunable Mo/Ce molar ratios by a one-potmethod and investigated their effect on chemodynamic therapy (CDT)and photothermal therapy (PTT). It is found that Ce-MoOv can self-assemble into nanoclusters in acidic conditions and theincreasing Ce amount will generate oxygen vacancy defects and inducethe valence change of Mo6+/Mo5+ and Ce4+/Ce3+, which leads to strong near-infrared absorptionwith high photothermal conversion efficiency of 71.31 and 49.86% for808 and 1064 nm. Other than photothermal conversion, the materialsdemonstrate pH-/glutathione (GSH)-activated photoacoustic (PA) imagingcapability in vitro. In addition, Ce-MoOv acts as a CDT reagent capable of converting endogenous H2O2 to two types of reactive oxygen species ((OH)-O-& BULL;, O-1(2)) while depleting GSH. Ce-MoOv demonstrates an excellent therapeutic effect against HCT116 cellsand effectively reduces the intracellular GSH level and significantlyincreases the number of reactive radicals under 1064 nm laser irradiationas compared with the no-laser group in vitro. Thiswork provides a new paradigm using lanthanide-doped polymetallic oxidesfor pH-/GSH-responsive photothermal/chemodynamic therapy with PA imagingability.

Automated summary

Cerium-doped MoO (x) (Ce-MoOv) nanomaterials with tunable Mo/Ce molar ratios were fabricated by a one-pot method and their effects on chemodynamic therapy (CDT) and photothermal therapy (PTT) were investigated. Ce-MoOv could self-assemble into nanoclusters in acidic conditions, and increasing the amount of Ce resulted in the generation of oxygen vacancy defects and changes in the valence states of Mo6+/Mo5+ and Ce4+/Ce3+. This led to strong near-infrared absorption and high photothermal conversion efficiency for 808 and 1064 nm. Ce-MoOv also demonstrated pH-/glutathione (GSH)-activated photoacoustic (PA) imaging capability and acted as a CDT reagent by converting H2O2 to reactive oxygen species and depleting GSH. The therapeutic effect of Ce-MoOv against HCT116 cells was highly effective under 1064 nm laser irradiation.