MRI Contrast Enhancement and Cell Labeling using Gd2O3 Nanoparticles

There is an increasing interest for nanomaterials in bio-medical applications and in this work, nanoparticles of gadolinium oxide (Gd2O3) have been investigated as a novel contrast agent for magnetic resonance imaging (MRI). Relaxation properties have been studied in aqueous solutions as well as in cell culture medium and the nanoparticles have been explored as cell labeling agents. The fluorescent properties of the particles were used to visualize the internalization in cells and doped particles were investigated as a multimodal agent that could work as a fluorescent marker for microscopy and as a contrast enhancer for MRI. Fluorescent studies show that the Gd2O3 nanoparticles doped with 5% terbium have interesting fluorescent properties and that these particles could work as such multimodal contrast agent. Relaxivity measurements show that in aqueous solutions, there is a twofold increase in relaxivity for Gd2O3 compared to commercial agent Gd-DTPA. In cell culture medium as well as in cells, there is a clear T1 effect and an increase in signal intensity in T1-mapped images. The cellular uptake of Gd2O3 nanoparticles were increased with the use of transfection agent protamine sulfate. This work shows that Gd2O3 nanoparticles possess good relaxation properties that are retained in different biological environments. Gd2O3 particles are suitable as a T1 contrast agent, but seem also be adequate for T2 enhancement in for instance cell labeling experiments.