A T₁, T₂ magnetic resonance imaging (MRI)-fluorescent imaging (FI) by using ultrasmall mixed gadolinium-europium oxide nanoparticles

Multiple molecular imaging is a challenging subject. Water-soluble and biocompatible lactobionic acid coated ultrasmall mixed gadolinium-europium oxide nanoparticles with an average particle diameter of 1.75 nm and an average hydrodynamic diameter of 4.16 nm were synthesized and applied for T₁, T₂ MRI-FI in vitro and in vivo. They had r₁ and r ₂ values of 11.9 and 38.7 s^-1 mM^-1, respectively, and showed clear dose-dependent contrast changes in both R ₁ and R₂ map images. In addition, they showed both positive and negative contrast enhancements in 3 tesla T₁ and T ₂ MR images in a mouse, respectively, and fluorescent confocal images in both DU145 cells and C. elegans (a small nematode). This study demonstrates the T₁, T₂ MRI-FI multi-functionality of lactobionic acid coated mixed gadolinium-europium oxide nanoparticles.