Na_0.3WO₃ nanorods: a multifunctional agent for in vivo dual-model imaging and photothermal therapy of cancer cells

The combination of imaging diagnosis and photothermal ablation (PTA) therapy has become a potential treatment for cancer. In particular, tungsten bronzes have a number of unique properties such as broad near-infrared (NIR) absorption and a large X-ray attenuation coefficient. However, these materials have seldom been reported as an X-ray computed tomography (CT) contrast agent and a photothermal agent. Herein, we synthesized PEGylated Na_0.3WO₃ nanorods (mean size similar to 39 nm x 5 nm) by a simple one-pot solvothermal route. As we expected, the prepared PEGylated Na_0.3WO₃ nanorods exhibit intense NIR absorption, derived from the outer d-electron of W5+. These PEGylated Na_0.3WO₃ nanorods also show an excellent CT imaging effect and a high HU value of 29.95 HU g L^-1 (much higher than the figure of iopamidol (19.35 HU g L^-1)), due to the intrinsic property of tungsten of large atomic number and X-ray attenuation coefficient. Furthermore, the temperature elevation and the in vivo photothermal experiment reveal that as-synthesized Na_0.3WO₃ nanorods could be an effective photothermal agent, as they have low toxicity, high effectiveness and good photostability.