Core-Shell Fe₃O₄@C Nanoparticles as Highly Effective T₂ Magnetic Resonance Imaging Contrast Agents: In Vitro and In Vivo Studies

Magnetite nanoparticles (Fe3O4 NPs) have been intensively investigated because of their potential biomedical applications due to their high saturation magnetization. In this study, core-shell Fe3O4@C NPs (core = Fe3O4 NPs and shell = amorphous carbons, d(avg) = 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 Fe3O4@C NPs exhibited ideal relaxometric properties for T-2 magnetic resonance imaging (MRI) contrast agents (i.e., high transverse and negligible longitudinal water proton spin relaxivities), making them exclusively induce only T-2 relaxation. Their T-2 MRI performance as contrast agents was confirmed in vivo by measuring T-2 MR images in mice before and after intravenous injection.