Clusters of Magnetic Nanoparticles as Contrast Agents for MRI: Effect of Aggregation on Transverse Relaxivity

The effect of aggregation of magnetic nanoparticles on the transverse relaxivity (r 2 ) is analyzed with respect to the size of clusters. The nanoparticles employed are based on La 0.75 Sr 0.25 MnO 3 ferromagnetic phase with the mean size of crystallites dXRD = 26 nm synthetized via sol-gel route fo...

Full description

Saved in:
Bibliographic Details
Published in:IEEE transactions on magnetics 2015-11, Vol.51 (11), p.1-4
Main Authors: Dedourkova, Tereza, Kaman, Ondrej, Veverka, Pavel, Koktan, Jakub, Veverka, Miroslav, Kulickova, Jarmila, Jirak, Zdenek, Herynek, Vit
Format: Article
Language:English
Subjects:
Agglomeration
Atmospheric measurements
Clusters
Contrast agents
Crystallites
Magnetic cores
magnetic nanoparticles
Magnetic resonance imaging
Magnetism
Manganites
Nanoparticles
Particle measurements
Silicon compounds
Silicon dioxide
Spectrum analysis
Temperature measurement
transverse relaxivity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The effect of aggregation of magnetic nanoparticles on the transverse relaxivity (r 2 ) is analyzed with respect to the size of clusters. The nanoparticles employed are based on La 0.75 Sr 0.25 MnO 3 ferromagnetic phase with the mean size of crystallites dXRD = 26 nm synthetized via sol-gel route followed by thermal treatment and mechanical processing. The subsequent silica coating provides colloidally stable particles whose magnetic cores are mostly composed of compact clusters of manganite crystallites. The product has been subjected to repeated differential centrifugation and several size fractions, possessing the same dXRD but differing in the effective size of magnetic cores, are isolated. Thorough analyses of their size distributions by transmission electron microscopy and dynamic light scattering measurements are carried out together with SQUID magnetometry. The concentration of particles in aqueous suspensions is accurately determined by atomic absorption spectroscopy and a detailed study of transverse relaxation at the magnetic field B 0 = 0.5 T is performed. The highest r 2 values are clearly observed for midsized clusters and the temperature dependence of r 2 resembles the evolution of magnetization with temperature. Supplemental samples with different thicknesses of the silica shell are also synthetized and thoroughly analyzed.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2015.2438112