Highly magnetic iron carbide nanoparticles as effective T₂contrast agents

This paper reports that iron carbide nanoparticles with high air-stability and strong saturation magnetization can serve as effective T2 contrast agents for magnetic resonance imaging. Fe5C2 nanoparticles (∼20 nm in diameter) exhibit strong contrast enhancement with an r2 value of 283.2 mM−1 S−1, which is about twice as high as that of spherical Fe3O4 nanoparticles (∼140.9 mM−1 S−1). In vivo experiments demonstrate that Fe5C2 nanoparticles are able to produce much more significant MRI contrast enhancement than conventional Fe3O4 nanoparticles in living subjects, which holds great promise in biomedical applications.