Unveiling the Influence of Interactions in the Behavior of Magnetic Nanoparticle Agglomerates: Experiments and Simulations

This presentation discusses the effects of magnetic nanoparticle (MNP) aggregation on a series of experimental measurements related to magnetic fluid hyperthermia (MFH). The investigation focuses on different agglomerate structures, especially those with elongated shapes. We analyze the influence of interparticle interactions through a combination of theoretical and experimental approaches. First, a novel perspective on magnetic behaviour is provided through the comparison of numerical simulations of non-interacting MNPs and chain systems, with magnetic anisotropy as a key parameter for the determination of the specific power absorption in MFH experiments. This view provides consistency to conflicting reports regarding interaction effects on the heating response. Second, we study cytosol phantoms with dispersed and oriented MNPs, extending our understanding beyond the initially simulated ideal chains. A novel method is employed to produce spatiotemporal 2D maps during MFH experiments which facilitates the identification of spatial MNP arrangements and their effect on the heating response. Finally, we were able to reproduce ac hysteresis loop measurements for these phantoms through the modeling of interactions in an effective way. This is achieved using input from previous simulations and experiments such as cryo FIB-SEM images of the phantoms.