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 r2 values of 11.9 and 38.7 s−1 mM−1, respectively, and showed clear dose-dependent contrast changes in both R1 and R2 map images. In addition, they showed both positive and negative contrast enhancements in 3 tesla T1 and T2 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.