Magnetosome-like nanoparticle systems for magnetic hyperthermia: modeling the effect of dipolar interactions

DANIELA P. VALDÉS; ROBERTO D. ZYSLER; ENIO LIMA JR.; EMILIO DE BIASI

Washington, DC

Conferencia; 2019 Joint MMM-Intermag Conference; 2019

IEEE Magnetics Society

Magnetic hyperthermia is being developed as a cancer treatment and consists on the incorporation of magnetic nanoparticles (NPs) on a tumor with their subsequent heating through the application of an alternating magnetic field. In this work, we present a study of the effect of the dipolar interactions between NPs on the area of the magnetization hysteresis loops. An increment in the area of the magnetization hysteresis loop represents a higher specific absorption rate (SAR), which means that a greater amount of energy can be liberated as heat. We considered NPs arranged in chains with uniaxial anisotropy (Fig.1), similarly to magnetosomes1. The magnetic behavior of the NPs is described by a previous model2 that considers the effects of temperature, as well as the frequency of the field sweep. In this new model, which goes beyond the linear response theory3, the magnetic field is corrected with interparticle interactions. Through its implementation, the case of low and high interaction was studied, varying the orientation (Φn) regarding the external magnetic field. To analyze these interactions, the parallel (Hdip‖) and perpendicular (Hdip⊥) components of the dipolar magnetic field, regarding the external one, were taken into account. An increment in the area of the hysteresis loops due to dipolar interactions is reported (Fig.2), either for isolated chains with a certain Φn or for randomly-oriented chains, which represents a higher SAR. It was seen that both components of the dipolar field present hysteresis as the external field is swept. It was also determined that Hdip⊥ always helps to increase the area of the magnetization loop, meanwhile Hdip‖ can or cannot help, depending on the strength of the interaction. To conclude, dipolar interactions in these kind of systems can help to improve hyperthermia significantly for some systems which can originally be far from the ideal conditions for the experiments.[1] S. Ghaisari, M. Winklhofer and P. Strauch, Biophysical Journal., Vol. 113, p.637 (2017) [2] E. De Biasi, R.D. Zysler and C.A. Ramos, Journal of Magnetism and Magnetic Materials., Vol. 320, p.e312 (2008)[3] R.E. Rosensweig, Journal of Magnetism and Magnetic Materials., Vol. 252, p.370 (2002)