A Novel Paramagnetic NanoparticleT(2)Magnetic Resonance Imaging Contrast Agent With High Colloidal Stability: PolyacrylicAcid-CoatedUltrafine Dysprosium Oxide Nanoparticles

Until now, there have been limited studies on T(2)magnetic resonance imaging (MRI) contrast agents (CAs) using paramagnetic nanoparticles (NPs). In this study, ultrafine dysprosium oxide (Dy2O3) NPs were synthesized as a T2MRI CA. To obtain high biocompatibility and colloidal stability in aqueous medium forin vivoapplications, they were grafted with polyacrylic acid. They displayed paramagnetism with an appreciable magnetization value at 300 K and consequently, an appreciable transverse water proton spin relaxivity (r(2)) value which increased as the applied MR field increased. Their potential as a T2MRI CA was proved by takingin vivoT(2)MR images in mice.