Synthesis, Characterizations, and 9.4 Tesla T2 MR Images of Polyacrylic Acid-Coated Terbium(III) and Holmium(III) Oxide Nanoparticles

Abstract

Polyacrylic acid (PAA)-coated lanthanide oxide (Ln₂O₃) nanoparticles (NPs) (Ln = Tb and Ho) with high colloidal stability and good biocompatibility were synthesized, characterized, and investigated as a new class of negative (T₂) magnetic resonance imaging (MRI) contrast agents at high MR fields. Their r₂ values were appreciable at a 3.0 T MR field and higher at a 9.4 T MR field, whereas their r₁ values were negligible at all MR fields, indicating their exclusive induction of T₂ relaxations with negligible induction of T₁ relaxations. Their effectiveness as T₂ MRI contrast agents at high MR fields was confirmed from strong negative contrast enhancements in in vivo T₂ MR images at a 9.4 T MR field after intravenous administration into mice tails.