Outersphere Approach to Increasing the Persistance of Oxygen-Sensitive Europium(II)-Containing Contrast Agents for Magnetic Resonance Imaging with Perfluorocarbon Nanoemulsions toward Imaging of Hypoxia.

Radiographic mapping of hypoxia is needed to study a wide range of diseases. Complexes of Eu II are a promising class of molecules to fit this need, but they are generally limited by their rapid oxidation rates in vivo. Here, a perfluorocarbon-nanoemulsion perfused with N 2 , forms an interface with aqueous layers to hinder oxidation of a new perfluorocarbon-soluble complex of Eu II . Conversion of the perfluorocarbon solution of Eu II into nanoemulsions results in observable differences between reduced and oxidized forms by MRI both in vitro and in vivo. Oxidation in vivo occurrs over a period of ∼30 min compared to <5 min for a comparable Eu II -containing complex without nanoparticle interfaces. These results represent a critical step toward delivery of Eu II -containing complexes in vivo for the study of hypoxia. This article is protected by copyright. All rights reserved.