Oxygen Vacancies Enhanced CeO₂:Gd Nanoparticles for Sensing a Tumor Vascular Microenvironment by Magnetic Resonance Imaging

The specific characteristics of the tumor vascular microenvironment such as microvascular permeability and water diffusion have been demonstrated to play essential roles in the evaluation of infiltration of tumors. However, at present, there are few contrast agents (CAs) for magnetic resonance imaging to enhance the sensitivity for acquiring this vital information. Herein, we develop Gd-doped (CeO₂:Gd) nanoparticles as CAs to detect the tumor vascular microenvironment with high sensitivity. The lattice oxygen vacancies on the surface of CeO₂:Gd nanoparticles could bind considerable water molecules to improve the r₁ value, achieving an excellent dynamic contrast-enhanced perfusion weighted imaging performance for the measurement of microvascular permeability. Diffusion limiting of water molecules by oxygen vacancies of CeO₂:Gd nanoparticles further enhances the diffusion-weighted magnetic resonance imaging signal in vitro and in vivo. Excitingly, the strategy is not only essential for obtaining tumor vascular microenvironment information but also offers a way for further research in the design of magnetic resonance CAs.