Highly magnetic iron carbide nanoparticles as effective T2 contrast agents

This paper reports that iron carbide nanoparticles with high air-stability and strong saturation magnetization can serve as effective T-2 contrast agents for magnetic resonance imaging. Fe5C2 nanoparticles (similar to 20 nm in diameter) exhibit strong contrast enhancement with an r(2) value of 283.2 mM(-1) S-1, which is about twice as high as that of spherical Fe3O4 nanoparticles (similar to 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.