A simple polyol-free synthesis route to Gd2O3 nanoparticles for MRI applications: an experimental and theoretical study

Abstract

In all kinds of gadolinium based contrast agents, the presence of free gadolinium ions have to be avoided due to the cytotoxicity. The conventional way of producing a gadolinium based contrast agent is to form a chelate, i.e. stabilizing the metal ion using a chelating agent (for example DTPA or DOTA) but recently nanoparticles is an initial step towards biocompatible and directed nanoparticles.The main focus is on a material that in the nearby future will be the core of an The experimental results are supported by theoretical modeling studies.Theoretical IR spectra of three different Gd acetate complexes are presented as well as calculated NEXAFS spectra of one of the Gd acetate complexes and an isolated acetate group. These calculations were performed to elucidate the molecular capping of the synthesized particles. 5 EXPERIMENTAL DETAILS ChemicalsAll chemicals were used as received. Gadolinium(III) acetate hydrate (SigmaAldrich, 99.9 %), tetramethylammonium hydroxide (Sigma-Aldrich, >97 % ), ethyl acetate (Fisher Scientific, 99.99 %), dimethyl sulfoxide (Merck, 99.9 %), ammonium acetate (Merck, >96%), ethanol (Kemetyl, 99.5 %). For preparation of water based solutions, Milli-Q water (ρ > 18.2 MΩ) was used. A commercial gadolinium oxide nanopowder (Aldrich, < 100 nm, 99.8 %) was used as a reference. Preparation of Gd 2 O 3 nanoparticlesThe preparation of Gd 2 O 3 nanoparticles was based on a method previously used for producing nanocrystalline ZnO (Schwartz et al. 2003). As Zn 2+ is divalent and Ethyl acetate was added and the mixture was centrifuge washed (3500 rpm) at least three times with ethyl acetate before it was diluted in deionized water. A total amount of 0.28 g ammonium acetate was added to one whole batch to increase the water solubility. Powder samples were air dried. The yield of the sample is dependent on the washing procedure. The gadolinium content after three times of centrifuge washing with ethyl acetate is roughly 60-65 % of the initial amount added in the synthesis.6 Instrumentation X-ray diffraction XRD measurements were carried out with a Philips XRD powder diffractometer using Cu Kα radiation (λ = 1.5418 Å, 40kV, 40 mA). The 2θ step-size was 0.025° and the time per step 4 s. Air dried powder samples were used in the preparation.High-resolution transmission electron microscopy TEM measurements were performed on a FEI Tecnai G 2 electron microscope operated at 200 kV. Sample preparation was done by letting 1-2 drops of Gd 2 O 3 in water dry on an amorphous carbon-covered copper grid.Dynamic light scattering DLS measurements were carried out on an ALV/DLS/SLS-5022F system from ALV-GmbH, Langen Germany, using a HeNe laser at 632.8 nm with 22 mW output power. Prior to the measurements, the samples were temperature stabilized in a thermostat bath at 22.1 °C for at least 10 minutes. The scattering angle was 90°. 15 Gd 2 O 3 samples dispersed in MilliQ water were studied in DLS, and the long term stability of the suspensions were studied by repeated measurements during a period of 6 weeks.ζ Pot...

Facile synthesis of gadolinium (III) chelates functionalized carbon quantum dots for fluorescence and magnetic resonance dual-modal bioimaging

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Preparation, characterization and X-ray attenuation property of Gd2O3-based nanocomposites

“…Monoclinic and cubic Gd 2 O 3 nanoparticles are paramagnetic in nature and become antiferromagnetic at a Neel temperature of 17.2 K (Jamnezhad and Jafari 2016). Gd 3? ion in gadolinium oxide possesses seven unpaired electrons in the 4f orbital with an electron spin of 7/2 (Ahren et al 2012). It exhibits a long electronic relaxation time of 10 -8 -10…”

Silica-Coated Europium-Doped Gadolinium Oxide Nanorods for Dual-Modal Imaging of Cancer Cells

“…Therefore, they are chelated to form a stable compound and thereby reduce the toxicity levels. 9 There are various methods to synthesize the gadolinium oxide nanoparticles such as polyol method, 10 co-precipitation method, 11 hydrothermal method, 12 sol-gel method, 13 template-assisted technique, 14 pulsed laser ablation, 15 pulsed electron beam evaporation 16 and mechano-chemical methods. 17 Di®erent morphologies of gadolinium oxide nanoparticles such as nanospheres, 18 nano¯bers, 19 nanotubes/ nanorods 20 and nanoplates 21 can be prepared by controlling the process parameters.…”