Synthesis and functionalization of Gd-based nanoparticles for MRI contrast enhancement

Abstract: Magnetic metal oxide nanoparticles for contrast enhancement in Magnetic Resonance Imaging (MRI) have proven to be one of the most promising applications in diagnostic science. The nanoparticles can provide better and more accurate diagnosis by their capability to enhance the contrast between different soft tissues. New and better contrast agents need to be developed, to further improve this contrast enhancement. This thesis is focused on biofunctionalization of gadolinium oxide (Gd2O3) nanoparticles to obtain specific properties for further functionalization with the long term goal to improve the biocompatibility and the biomolecular recognition. Gd2O3 nanoparticles have been synthesized by a polyol synthesis and characterized with Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS) and Dynamic Light Scattering (DLS). Three different capping procedures of Gd2O3 nanoparticles was investigated to obtain improved stability and to present functional groups for further functionalization. Capping molecules used was oleic acid, citric acid and 3-aminopropyl-triethoxysilane (APTES). The presence of oleic acid and citric acid was examined with Fourier Transform Infrared Transmission (FT-IR) and XPS. The crystalline nature of Gd2O3 when capped with oleic acid and citric acid was also examined using X-ray powder diffraction (XRPD) and TEM. The capping layer from APTES was examined using XPS and DLS. Dialysis and filtration has a crucial role in decreasing the risk of aggregation and increasing the possibilities for functionalization of the Gd2O3 nanoparticles. Diafiltration procedure was studied which may lead to better and quicker filtration.