Fluoride doped γ-Fe2O3 nanoparticles with increased MRI relaxivity. Issue 22 (9th April 2018)

• Record Type: Journal Article
• Authors: Jones, N. E.; Burnett, C. A.; Salamon, S.; Landers, J.; Wende, H.; Lazzarini, L.; Gibbs, P.; Pickles, M.; Johnson, B. R. G.; Evans, D. J.; Archibald, S. J.; Francesconi, M. G.
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 22(2018)
• Page Start: 3665
• Page End: 3673
• Publication Date: 2018-04-09
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Biomedical materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8tb00360b
• Languages: English
• ISSNs: 2050-750X

Abstract

Abstract : Fluoride doping in γ-Fe2 O3 nanoparticles induces large increases in magnetic anisotropy and relaxivities, r 1 and r 2 . Abstract : 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, r 1 and r 2 . γ-Fe2 O3 nanoparticles – doped with fluoride in a controlled manner and functionalised with citric acid – showed a 3-fold increase in r 1 and a 17-fold increase in r 2 in a magnetic field of 3 T and almost 6-fold increase in r 1 and a 14-fold increase in r 2 at 11 T. Following fluorination, PXRD shows that the crystal structure of γ-Fe2 O3 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-Fe2 O3 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-Fe2 O3 nanoparticles.