Neumann, S. / Kuger, L. / Arlt, C. R. / Franzreb, M. / Rafaja, D. (2023)

Microscopy and Microanalysis, 2023, 29, 1, 1985, doi.org/10.1093/micmic/ozad067.1028

Multi-core iron oxide nanoparticles, often called iron oxide nanoflowers (IONFs), exhibit a combination of excellent properties including superparamagnetic behavior, high saturation magnetization and a good biocompatibility. Therefore, IONFs have found widespread biomedical application, for example as heat mediator for hyperthermia cancer treatment. While the magnetic properties of mono-core iron oxide nanoparticles are controlled mainly by their size, the magnetic properties of IONFs are additionally affected by the interaction of magnetic moments between neighboring cores. However, a detailed description of the complex internal structure of multi-core IONFs has not been provided so far.

The aim of this study was to reveal the hierarchical structure of multi-core IONFs, including the orientation relationships between individual cores, their internal structure and crystallographic coherence of the core fragments, and to relate these phenomena to the magnetic properties of the multi-core IONFs. The IONFs investigated here were commercially available, dextran-coated multi-core IONFs (synomag-D, micromod Partikeltechnologie GmbH, Rostock, Germany), which were synthesized using a polyol method [1]. Their structural characteristics were investigated using transmission electron microscopy (TEM) that was applied in high-resolution and low-resolution modes and networked by a correlative multiscale approach [2], and correlated with the magnetic properties concluded from the magnetization curve measured using alternating gradient magnetometry (AGM).

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