Manganese Dioxide Coated WS @Fe O /sSiO Nanocomposites for pH-Responsive MR Imaging and Oxygen-Elevated Synergetic Therapy.

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 (WS ) nanoflakes with their surface adsorbed with iron oxide nanoparticles (IONPs) via self-assembly are coated with silica and then subsequently with manganese dioxide (MnO ), on to which polyethylene glycol (PEG) is attached. The obtained WS -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 MnO as the pH-sensitive T1 contrast probe. Meanwhile, synergistic combination tumor therapy is realized with such WS -IO/S@MO-PEG, by utilizing the strong near-infrared light and X-ray absorbance of WS for photothermal therapy (PTT) and enhanced cancer radiotherapy (RT), respectively, as well as the ability of MnO to decompose tumor endogenous H O and relieve tumor hypoxia to further overcome hypoxia-associated radiotherapy resistance. The combination of PTT and RT with WS -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.