High Longitudinal Relaxivity Of Ultra-Small Gadolinium Oxide Prepared By Microsecond Laser Ablation In Diethylene Glycol

Ultra-small gadolinium oxide (Gd2O3) can be used as T-1-weighted Magnetic Resonance Imaging (MRI) contrast agent own to its high longitudinal relaxivity (r(1)) and has attracted intensive attention in these years. In this paper, ultra-small Gd2O3 nanoparticles of 3.8 nm in diameter have been successfully synthesized by a microsecond laser ablating a gadolinium (Gd) target in diethylene glycol (DEG). The growth inhibition effect induced by the large viscosity of DEG makes it possible to synthesize ultra-small Gd2O3 by laser ablation in DEG. The r(1) value and T-1-weighted MR images are measured by a 3.0 T MRI spectroscope. The results show these nanoparticles with a high r(1) value of 9.76 s(-1) mM(-1) to be good MRI contrast agents. We propose an explanation for the high r(1) value of ultra-small Gd2O3 by considering the decreasing factor (surface to volume ratio of the nanoparticles, S/V) and the increasing factor (water hydration number of the Gd3+ on Gd2O3 surface, q), which offer a new look into the relaxivity studies of MRI contrast agents. Our research provides a new approach to preparing ultra-small Gd2O3 of high r(1) value by laser ablation in DEG and develops the understanding of high relaxivity of ultra-small Gd2O3 MRI contrast agents. (C) 2013 AIP Publishing LLC.