Manganese oxide/Metal-Organic Frameworks-Based Nanocomposites for Tumr Micro-environment Sensitive 1H/19F Dual-mode Magnetic Resonance Imaging in Vivo

Abstract A pH- and GSH-responsive 1H/19F dual-mode magnetic resonance imaging contrast agent (MRI CA) was constructed by incorporating MnOx into Zr-based MOF nanoparticles (MnOx/UiO-66-F/PPEG NPs) with an organic ligand of tetrafluoro-terephthalic acid (F4PTA). Under a weak acidic tumor micro-environment, MnOx/UiO-66-F/PPEG NPs would collapse to release MnOx and free F4PTA. Due to the released free F4PTA, 19F MRI signal was enhanced. Meanwhile, GSH, which is overexpressed in a tumor micro-environment, reduced MnOx to divalent manganese ions and improved the T1-weighted MR imaging capability. As a proof of concept, MnOx/UiO-66-F/PPEG NPs was favorable for dual 1H/19F MRI with a high signal-to-noise ratio in vivo.