A Novel Paramagnetic Nanoparticle T₂ Magnetic Resonance Imaging Contrast Agent With High Colloidal Stability: Polyacrylic Acid-Coated Ultrafine Dysprosium Oxide Nanoparticles

Until now, there have been limited studies on T₂ magnetic resonance imaging (MRI) contrast agents (CAs) using paramagnetic nanoparticles (NPs). In this study, ultrafine dysprosium oxide (Dy₂O₃) NPs were synthesized as a T₂ MRI CA. To obtain high biocompatibility and colloidal stability in aqueous medium for in vivo applications, 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 (r₂) value which increased as the applied MR field increased. Their potential as a T₂ MRI CA was proved by taking in vivo T₂ MR images in mice.