Ligand-size dependent water proton relaxivities in ultrasmall gadolinium oxide nanoparticles and in vivo T 1 MR images in a 1.5 T MR field

The dependence of longitudinal ( r 1 ) and transverse ( r 2 ) water proton relaxivities of ultrasmall gadolinium oxide (Gd 2 O 3 ) nanoparticles on the surface coating ligand-size was investigated. Both r 1 and r 2 values decreased with increasing ligand-size. We attributed this to the ligand-size effect. In addition the effectiveness of d -glucuronic acid-coated ultrasmall Gd 2 O 3 nanoparticles as T 1 magnetic resonance imaging (MRI) contrast agents was confirmed by measuring the in vitro cytotoxicity and using in vivo T 1 MR images in a mouse in a 1.5 T MR field.