Bottom-Up Synthesis of Metal-Ion-Doped WS₂ Nanoflakes for Cancer Theranostics

Abstract

Recently, two-dimensional transition metal dichalcogenides (TMDCs) have received tremendous attention in many fields including biomedicine. Herein, we develop a general method to dope different types of metal ions into WS₂ nanoflakes, a typical class of TMDCs, and choose Gd³⁺-doped WS₂ (WS₂:Gd³⁺) with polyethylene glycol (PEG) modification as a multifunctional agent for imaging-guided combination cancer treatment. While WS₂ with strong near-infrared (NIR) absorbance and X-ray attenuation ability enables contrasts in photoacoustic (PA) imaging and computed tomography (CT), Gd³⁺ doping offers the nanostructure a paramagnetic property for magnetic resonance (MR) imaging. As revealed by trimodal PA/CT/MR imaging, WS₂:Gd³⁺-PEG nanoflakes showed efficient tumor homing after intravenous injection. <i>In vivo</i> cancer treatment study further uncovered that WS₂:Gd³⁺-PEG could not only convert NIR light into heat for photothermal therapy (PTT) but also enhance the ionizing irradiation-induced tumor damage to boost radiation therapy (RT). Owing to the improved tumor oxygenation after the mild PTT, the combination of PTT and RT induced by WS₂:Gd³⁺-PEG resulted in a remarkable synergistic effect to destroy cancer. Our work highlights the promise of utilizing inherent physical properties of TMDC-based nanostructures, whose functions could be further enriched by elementary doping, for applications in multimodal bioimaging and synergistic cancer therapy