Manganese Dioxide Coated WS2 @Fe3 O4 /sSiO2 Nanocomposites for pH-Responsive MR Imaging and Oxygen-Elevated Synergetic Therapy

Abstract

Recently, the development of multifunctional theranostic nanoplatforms to realize tumor-specific imaging and enhanced cancer therapy via responding or modulating the tumor microenvironment (TME) has attracted tremendous interests in the field of nanomedicine. Herein, tungsten disulfide (WS₂ ) nanoflakes with their surface adsorbed with iron oxide nanoparticles (IONPs) via self-assembly are coated with silica and then subsequently with manganese dioxide (MnO₂ ), on to which polyethylene glycol (PEG) is attached. The obtained WS₂ -IO/S@MO-PEG appears to be highly sensitive to pH, enabling tumor pH-responsive magnetic resonance imaging with IONPs as the pH-inert T2 contrast probe and MnO₂ as the pH-sensitive T1 contrast probe. Meanwhile, synergistic combination tumor therapy is realized with such WS₂ -IO/S@MO-PEG, by utilizing the strong near-infrared light and X-ray absorbance of WS₂ for photothermal therapy (PTT) and enhanced cancer radiotherapy (RT), respectively, as well as the ability of MnO₂ to decompose tumor endogenous H₂ O₂ and relieve tumor hypoxia to further overcome hypoxia-associated radiotherapy resistance. The combination of PTT and RT with WS₂ -IO/S@MO-PEG results in a remarkable synergistic effect to destruct tumors. This work highlights the promise of developing multifunction nanocomposites for TME-specific imaging and TME modulation, aiming at precision cancer synergistic treatment.

Keywords: WS2 nanoflakes; combination tumor therapy; manganese dioxide; tumor microenvironment; tumor-specific imaging.