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

通过将MnO _x掺入Zr基MOF纳米颗粒（MnO _x / UiO-66-F / PPEG NPs）中，构建pH和GSH响应的¹ H / ¹⁹ F双模磁共振成像造影剂（MRI CA ）。四氟对苯二甲酸（F ₄ PTA）的有机配体。在弱酸性肿瘤微环境下，MnO _x / UiO-66-F / PPEG NPs会坍塌释放出MnO _x和游离的F ₄ PTA。由于释放的自由F ₄ PTA，增强了¹⁹ F MRI信号。同时，在肿瘤微环境中过表达的谷胱甘肽可将MnO _x还原为二价锰离子并改善T₁加权MR成像功能。作为概念的证明，MnO _x / UiO-66-F / PPEG NP在体内具有高信噪比的双重¹ H / ¹⁹ F MRI上是有利的。