Rapid microwave-assisted synthesis of PVP-coated ultrasmall gadolinium oxide nanoparticles for magnetic resonance imaging

Synthesis of polyvinyl pyrrolidone (PVP) coated ultrasmall Gd2O3 nanoparticles (NPs) with enhanced T-1-weighted signal intensity and r(2)/r(1) ratio close to unity is performed by a microwave-assisted polyol process. PVP coated Gd(2)O(3)NPs with spherical shape and uniform size of 2.5 +/- 0.5 nm have been synthesized below 5 min and structure and morphology confirmed by HRTEM, XRD and FTIR. The longitudinal (r(1)) and transversal relaxation (r(2)) of Gd(2)O(3)NPs is measured by a 3 T MRI scanner. The results showed considerable increasing of relaxivity for Gd(2)O(3)NPs in comparison to gadolinium chelates which are commonly used for clinical magnetic resonance imaging. In addition, a mechanism for Gd(2)O(3)NPs formation and in situ surface modification of PVP-grafted Gd(2)O(3)NPs is proposed. (C) 2015 Elsevier B.V. All rights reserved.