Water-soluble ultrasmall Eu2O3 nanoparticles as a fluorescent imaging agent: In vitro and in vivo studies

The water-soluble d-glucuronic acid coated ultrasmall Eu2O3 nanoparticles with particle diameters ranging from 1.0 to 3.0 nm and with a hydrodynamic diameter of 4.71 nm were synthesized in one-pot solution phase reaction and their fluorescent imaging properties were characterized in vitro and in vivo. They showed a strong fluorescence in the red region, a high photostability, a narrow bandwidth, and non-toxicity up to 0.5 mM Eu, which is suitable for a high performance fluorescent imaging agent. This was proved in in vitro intracellular imaging of DU 145 cells and in vivo imaging of a digestive system of a small animal Caenorhabditis elegans.