Fabrication of dopamine enveloped WO3-x quantum dots as single-NIR laser activated photonic nanodrug for synergistic photothermal/photodynamic therapy against cancer

Tungsten oxide is a promising nanodrug in phototherapy via transforming light energy to reactive oxygen species and heat. Nevertheless, the phototherapeutic activity of the tungsten oxide nanomaterials is generally activated under 980 nm laser, which is close to the absorption of normal tissue, resulting in unfavorable heating effect on normal tissues. Therefore, the tungsten oxide nanomaterials which can be excited under 808 nm are highly required to avoid overheating and obtain deep tissue penetration of near-infrared (NIR) laser. Here, we successfully synthesized a novel dopamine enveloped tungsten oxide nanodots (WO3-x/Dpa-Mel NPs) via facile one-step solvothermal route, using dopamine as the template and reductant in triethylene glycol solvent. Under the 808 nm laser irradiation, the as-obtained WO3-x/Dpa-Mel NPs exhibit excellent photodynamic activity and stability. Meanwhile, the WO3-x/Dpa-Mel NPs also possess high photothermal conversion property. Thus, the photothermal therapy (PTT) and photodynamic therapy (PDT) can be triggered simultaneously under single 808 nm laser irradiation. Additionally, the inherited good biocompatibility and dispersity in aqueous solution from dopamine hydrochloride (Dpa-Mel) also make the WO3-x/Dpa-Mel NPs more suitable for in vivo application. The as-obtained WO3-x/Dpa-Mel NPs exhibit an excellent synergistic phototherapy effect on solid tumor ablation in vivo without damaging healthy tissues under single 808 nm NIR light irradiation, indicating WO3-x/Dpa-Mel NPs can serve as a multifunctional therapeutic nanoplatform to realize the synergistic cancer therapy.