Hexagonal NaxWO3 nanocrystals with reversible valence states for microwave thermal and chemodynamic combined cancer therapy

Microwave ablation (MWA) is recognized as the mainstream choice for tumor thermal ablation, but the rapid diffusion of heat and high tumor recurrence rate are still the primary bottlenecks in the clinic application of MWA. Hexagonal tungsten oxide nanomaterials could be potentially exploited as microwave sensitizers to elevate MWA efficacy due to the inherent tunnel structure and ions intercalation characteristics. Importantly, the flexible redox states of W element make it promising candidates for chemodynamic therapy (CDT) to further improve microwave-mediated cancer treatment. Herein, multifunctional hexagonal phase NaxWO3 nanocrystals modified with polyvinylpyrrolidone are prepared. Such NaxWO3 nanocrystals could not only function as microwave sensitizers to produce microwave heating effects for cancer cell killing, but also act as nano-catalyst to decompose hydrogen peroxide into highly oxidative hydroxyl radicals and simultaneously consume intracellular glutathione for an enhanced CDT effect. In addition, the hyperthermia generated by microwave irradiation could further upgrade the efficacy of CDT, achieving a combined effect of MWA and heat-amplified CDT. Notably, NaxWO3 nanocrystals enable the effective destruction of tumor tissues under microwave irradiation without inducing significant side effects to normal tissues. Consequently, our findings propose an innovative and safe nanotechnology strategy to reinforce the therapeutic outcome of MWA and CDT.