NMR relaxometric properties and cytotoxicity of Gd2O3 nanoparticle suspensions in an organic liquid

Gd2O3 nanoparticles of 10 to 80 nm in size suspended in an organic liquid was synthesized via polyol route. The reaction between diethylene glycol and added acetic acid, which occurred simultaneously with the synthesis of Gd2O3 nanoparticles, was catalyzed by sodium bisulfate to transform as much as possible diethylene glycol in corresponding ester at the end of complete reaction. The produced nanosized material of gadolinium oxide was investigated by TEM, DLS, FTIR spectroscopy and NMR relaxometry. Biological evaluation of this material was done by MTT and crystal violet assays to determine the cell viability. Longitudinal and transverse relaxivities of the Gd2O3 nanoparticle suspensions estimated to be r1 = 13.6 and r2 = 14.4 s-1 mM-1 are 2-3 times higher compared to the relaxivities of standard contrast agent Gd-DTPA (Magnevist). Good MRI signal intensities of the Gd2O3 nanoparticle suspensions were recorded in the Gd concentration range 0.2-0.3 mM for which the suspensions were not toxic exhibiting simultaneously higher signal intensities than those of Magnevist for Gd concentrations 0.4-1 mM for which this standard contrast agent was not toxic. These properties make the produced Gd2O3 nanoparticle material promising for potential application as MRI contrast agent.