Self-assembled WO3–x hierarchical nanostructures for photothermal therapy with a 915 nm laser rather than the common 980 nm laser.

Photothermal therapy (PTT) is limited by unsuitable photothermal agents and near-infrared (NIR) light. Herein, self-assembled PEGylated WO3–x hierarchical nanostructures, which could serve as excellent laser-cavity mirrors, were successfully prepared via a simple one-pot solvothermal route. The as-prepared WO3–x hierarchical nanostructures displayed strong near-infrared absorption. The absorption of pure water at 980 nm is 30 times higher than that at 915 nm, and the temperature of water only increased by 3.4 °C under the irradiation of a 915 nm laser with a power density of 1.0 W cm−2 for 10 min, while the temperature of water increased as much as 15.1 °C for the 980 nm laser. With continuous excitation by 915 nm light, the photothermal conversion efficiency of these WO3–x hierarchical nanostructures was evaluated to be 28.1%. Thus, the WO3–x hierarchical nanostructures could serve as excellent laser-cavity mirrors of a 915 nm laser. The PTT study on cancer cells in vivo demonstrated that the WO3–x hierarchical nanostructures can generate enough heat for efficient photothermal therapy of cancer cells under the irradiation of a 915 nm laser with a power density of 1.2 W cm−2 over a short period (5–10 min). [ABSTRACT FROM AUTHOR]