Core-Shell FeO@C Nanoparticles as Highly Effective T Magnetic Resonance Imaging Contrast Agents: In Vitro and In Vivo Studies.

Magnetite nanoparticles (FeO NPs) have been intensively investigated because of their potential biomedical applications due to their high saturation magnetization. In this study, core-shell FeO@C NPs (core = FeO NPs and shell = amorphous carbons, d = 35.1 nm) were synthesized in an aqueous solution. Carbon coating terminated with hydrophilic -OH and -COOH groups imparted excellent biocompatibility and hydrophilicity to the NPs, making them suitable for biomedical applications. The FeO@C NPs exhibited ideal relaxometric properties for T magnetic resonance imaging (MRI) contrast agents (i.e., high transverse and negligible longitudinal water proton spin relaxivities), making them exclusively induce only T relaxation. Their T MRI performance as contrast agents was confirmed in vivo by measuring T MR images in mice before and after intravenous injection.