Ligand-size dependent water proton relaxivities in ultrasmall gadolinium oxide nanoparticles and in vivo T₁ MR images in a 1.5 T MR field

The dependence of longitudinal (r₁) and transverse (r₂) water proton relaxivities of ultrasmall gadolinium oxide (Gd₂O₃) nanoparticles on the surface coating ligand-size was investigated. Both r₁ and r₂ values decreased with increasing ligand-size. We attributed this to the ligand-size effect. In addition the effectiveness of d-glucuronic acid-coated ultrasmall Gd₂O₃ nanoparticles as T₁ magnetic resonance imaging (MRI) contrast agents was confirmed by measuring the in vitro cytotoxicity and using in vivo T₁ MR images in a mouse in a 1.5 T MR field.