In Vivo Positive Magnetic Resonance Imaging Applications of Poly(methyl vinyl ether-alt-maleic acid)-coated Ultra-small Paramagnetic Gadolinium Oxide Nanoparticles

The study of ultra-small paramagnetic gadolinium oxide (Gd O ) nanoparticles (NPs) as in vivo positive (T ) magnetic resonance imaging (MRI) contrast agents is one of the most attractive fields in nanomedicine. The performance of the Gd O NP imaging agents depends on the surface-coating materials. In this study, poly(methyl vinyl ether-alt-maleic acid) (PMVEMA) was used as a surface-coating polymer. The PMVEMA-coated paramagnetic ultra-small Gd O NPs with an average particle diameter of 1.9 nm were synthesized using the one-pot polyol method. They exhibited excellent colloidal stability in water and good biocompatibility. They also showed a very high longitudinal water proton spin relaxivity (r ) value of 36.2 s mM (r /r = 2.0; r = transverse water proton spin relaxivity) under a 3.0 tesla MR field which is approximately 10 times higher than the r values of commercial molecular contrast agents. High positive contrast enhancements were observed in in vivo T MR images after intravenous administration of the NP solution sample, demonstrating its potential as a T MRI contrast agent.