Core-Shell Fe 3 O 4 @C Nanoparticles as Highly Effective T 2 Magnetic Resonance Imaging Contrast Agents: In Vitro and In Vivo Studies.

Magnetite nanoparticles (Fe 3 O 4 NPs) have been intensively investigated because of their potential biomedical applications due to their high saturation magnetization. In this study, core-shell Fe 3 O 4 @C NPs (core = Fe 3 O 4 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 Fe 3 O 4 @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.