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Issue 22, 2018
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Fluoride doped γ-Fe2O3 nanoparticles with increased MRI relaxivity

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Iron oxide nanoparticles (IONs) are being actively researched and experimented with as contrast agents for Magnetic Resonance Imaging (MRI), as well as image-directed delivery of therapeutics. The efficiency of an MRI contrast agent can be described by its longitudinal and transverse relaxivities, r1 and r2. γ-Fe2O3 nanoparticles – doped with fluoride in a controlled manner and functionalised with citric acid – showed a 3-fold increase in r1 and a 17-fold increase in r2 in a magnetic field of 3 T and almost 6-fold increase in r1 and a 14-fold increase in r2 at 11 T. Following fluorination, PXRD shows that the crystal structure of γ-Fe2O3 is maintained, Mössbauer spectroscopy shows that the oxidation state of the Fe cation is unchanged and HREM shows that the particle size does not vary. However, magnetisation curves show a large increase in the coercive field, pointing towards a large increase in the magnetic anisotropy for the fluorinated nanoparticles compared to the un-doped γ-Fe2O3 nanoparticles. Therefore, a chemically induced increase in magnetic anisotropy appears to be the most relevant parameter responsible for the large increase in relaxivity for γ-Fe2O3 nanoparticles.

Graphical abstract: Fluoride doped γ-Fe2O3 nanoparticles with increased MRI relaxivity

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Article information

05 Feb 2018
28 Mar 2018
First published
04 Apr 2018

J. Mater. Chem. B, 2018,6, 3665-3673
Article type

Fluoride doped γ-Fe2O3 nanoparticles with increased MRI relaxivity

N. E. Jones, C. A. Burnett, S. Salamon, J. Landers, H. Wende, L. Lazzarini, P. Gibbs, M. Pickles, B. R. G. Johnson, D. J. Evans, S. J. Archibald and M. G. Francesconi, J. Mater. Chem. B, 2018, 6, 3665
DOI: 10.1039/C8TB00360B

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