@article { , title = {Fluoride doped γ-Fe2O3 nanoparticles with increased MRI relaxivity}, 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-Fe 2 O 3 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-Fe 2 O 3 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-Fe 2 O 3 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-Fe 2 O 3 nanoparticles.}, doi = {10.1039/c8tb00360b}, eissn = {2050-750X}, issn = {2050-750X}, issue = {22}, journal = {Journal of Materials Chemistry B}, note = {This journal is Cite this:}, pages = {3665-3673}, publicationstatus = {Published}, publisher = {Royal Society of Chemistry}, url = {https://hull-repository.worktribe.com/output/778312}, volume = {6}, keyword = {Hull Molecular Imaging Centre, Health and Health Inequalities, General Materials Science, General Chemistry, Biomedical Engineering, General Medicine}, year = {2018}, author = {Jones, N. E. and Burnett, C. A. and Salamon, S. and Landers, J. and Wende, H. and Lazzarini, L. and Gibbs, P. and Pickles, M. and Johnson, B. R.G. and Evans, D. J. and Archibald, S. J. and Francesconi, M. G.} }