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Structure and magnetism of magnetic nanoparticles

Iron oxide nanoparticles being non-toxic have a huge potential for their utilization in medicine for drug delivery, imaging and hyperthermia. However, their size after synthesis is of crucial importance – the nanoparticles should be neither too large in order to avoid blood clots in capillaries nor too small in order for the system to be still responsive to an external magnetic field under the blood flow conditions. The knowledge of the properties of the interface between iron oxide nanoparticles and the biocompatible shell is of utmost importance to avoid blocked reactivity of the nanoparticles and develop a functionalization strategy.

At the same time, the magnetic properties of the iron oxide nanoparticles are intricately linked to their crystallographic structure, which might be altered by the coating agents. Iron oxide nanoparticles may have a magnetically disordered surface layer, contain anti-phase boundaries or have multiple iron oxide phases within their core (e.g. magnetite, maghemite, wüstite). Such effects lead to a reduction of saturation magnetization and efficiency of the nanoparticles in the theranostics.

We study the above mentioned effects by a set of complementary techniques, such as magnetometry, electron microscopy, small-angle scattering of neutrons and X-rays, pair distribution function.

Magnetic nanoparticle with multiphase coreA schematic representation of a magnetic nanoparticle with multiphase core, antiphase boundaries and magnetically depleted surface layer coated with a shell of organic molecules. Small-angle scattering of polarized neutrons allows simultaneous variation of nuclear and magnetic contrast in the sample for reliable structure determination.
Copyright: Forschungszentrum Jülich


  1. T. Köhler, A. Feoktystov, O. Petracic, E. Kentzinger, T. Bhatnagar-Schöffmann, M. Feygenson, N. Nandakumaran, J. Landers, H. Wende, A. Cervellino, U. Rücker, A. Kovacs, R. E. Dunin-Borkowski, and T. Brückel, Nanoscale 13, 6965 (2021) ,Mechanism of magnetization reduction in iron oxide nanoparticles, Nanoscale 13, 6965 (2021) 
  2. D. Zákutná, D. Nižňanský, L. C. Barnsley, E. Babcock, Z. Salhi, A. Feoktystov, D. Honecker, and S. Disch, Field Dependence of Magnetic Disorder in Nanoparticles, Phys. Rev. X 10, 031019 (2020) 
  3. J. Zaloga, A. Feoktystov, V. M. Garamus, W. Karawacka, A. Ioffe, T. Brückel, R. Tietze, C. Alexiou, and S. Lyer, Studies on the adsorption and desorption of mitoxantrone to lauric acid/albumin coated iron oxide nanoparticles, Colloids and Surfaces B: Biointerfaces 161, 18 (2018) 


Artem Feoktystov
Phone: +49 89 158860-746