Synthesis and Surface Modification of Gadolinium Compounds for Improvement of Magnetic Resonance Imaging

Abstract

Several morphologies of Gd(OH)3 and Gd2O3:Eu3+ particles (nano rods, micro rods, nano particles, nano plates, hexagonal hollow tubes, spheres, hexagonal prisms and hexagonal rods) were synthesized by a solvothermal reaction method and were used to enhance the photoluminescence intensity and magnetic resonance image (MRI) brightness. In the case of Gd(OH)3 particles with nano rods, micro rods, nano particles and nano plates, the influence of types (De-ionized water (DI-water), ethanol (EtOH), acetone (AC) and 2-propanol (2-PrOH)) and solvent ratio (mL) (40/0, 30/10, 20/20, 10/30 and 0/40) on the size and morphology of Gd(OH)3 particles was analyzed. The X-ray diffraction (XRD) patterns were confirmed the hexagonal structure. The field emission scanning electron microscopy (FE-SEM) images exhibited the morphology alteration of Gd(OH)3 with different solvents (DI-water: nano rods, EtOH: micro rods, AC: nano particles and 2-PrOH: nano plates) due to the solvent effects (solubility, dielectric constant and surface tenstion). The growth mechanism, morphology and size of the Gd(OH)3 particles were found to have a crucial influence on the solvents. Their one-, two- and three-dimensional structures affect materials to change magnetic property. Therefore, the MRI brightness of these particles also was affected. The relaxivity values of Gd(OH)3 particles have 3.47 mM-1s-1 (nano rods), 2.58 mM-1s-1 (micro rods), 7.17 mM-1s-1 (nano particles), 6.01 mM-1s-1 (nano plates). The influence of solvent ratio (DI-water/toluene (TL)) (mL): 40/0, 30/10, 20/20, 10/30 and 0/40) on the size and morphology of Gd2O3:Eu3+ particles (nano rods and hollow tubes) were analyzed. The XRD patterns were confirmed their cubic structure. The FE-SEM images exhibited the morphology alteration of Gd2O3:Eu3+ with different solvent ratios which induce the property variation (luminescence intensity and MRI brightness). The photoluminescence excitation (PLE) and photoluminescence emission (PL) spectra exhibited the broad band with dominant excitation wavelength of 266 nm due to the charge transfer band (CTB) and sharp band at 612 nm (red color). The PL intensity of Gd2O3:Eu3+ particles with DI-water 40/TL 0 is much higher than others. The MRI of Gd2O3:Eu3+ with DI-water 0/TL 40 is much brighter than others. Gd2O3:Eu3+ particles (spheres, hexagonal prisms and hexagonal rods) with the influence of pH values (pH 6: nitric acid, pH 10: ammonium hydroxide and pH 12: ammonium hydroxide) on the size and morphology of Gd2O3:Eu3+ particles were analyzed. The XRD patterns appeared the cubic structure. The FE-SEM images exhibited the morphology alteration of Gd2O3:Eu3+ with different pH values (pH 6: spheres, pH 10: hexagonal prisms and pH 12: hexagonal rods) which induce the property variation (luminescence intensity and MRI brightness). The process is very simple and scalable. In additions, it can be used for fundamental studies of the tunable sizes and morphologies formation which were influenced for the PL intensity and MRI brightness. Therefore, we consider that such multifunctional materials based on multiform Gd2O3:Eu3+ will be of interest for various advanced applications as MRI contrast agent and fluorescence imaging.