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Multiparametric Magnetic Particle Spectroscopy of CoFe₂O₄ Nanoparticles in Viscous Media

Draack, Sebastian, Lucht, Niklas, Remmer, Hilke, Martens, Michael, Fischer, Birgit, Schilling, Meinhard, Ludwig, Frank, Viereck, Thilo
Journal of physical chemistry 2019 v.123 no.11 pp. 6787-6801
image analysis, magnetic fields, magnetic resonance imaging, models, nanoparticles, physical chemistry, spectroscopy, therapeutics, viscosity
A detailed signal generation of the magnetization response of magnetic nanoparticles (MNPs) as a result of externally applied magnetic fields with flux densities of several millitesla is of high interest for biomedical applications such as magnetic resonance imaging or magnetic particle imaging (MPI). Although, MNPs are already frequently used as contrast agents or tracer materials, experimental data are rarely compared to model predictions because of distinct deviations. In this article, we use a customized Brownian-dominated CoFe₂O₄ particle system to compare experimental magnetic particle spectroscopy data with Fokker–Planck simulations considering the Brownian relaxation. The influences of viscosity, size distribution, excitation frequency, and field amplitude are studied. We show that the effective magnetic moment and cluster sizes can be determined using a sample viscosity series. As introduced, such particle systems can serve as model systems to evaluate mathematical expressions and to study dependences on physical influencing factors. Investigations of defined MNP systems and detailed characterizations enable a wide field of improved diagnosis and therapy applications, for example, mobility MPI and magnetic hyperthermia.