Efficiency of magnetic hyperthermia in the presence of rotating and static fields

Abstract

Single-domain ferromagnetic nanoparticle systems can be used to transfer energy from a timedependent magnetic field into their environment. This local heat generation, i.e., magnetic hyperthermia, receives applications in cancer therapy which requires the enhancement of the energy loss. A possible way to improve the efficiency is to chose a proper type of applied field, e.g., a rotating instead of an oscillating one. The latter case is very well studied and there is an increasing interest in the literature to investigate the former although it is still unclear under which circumstances the rotating applied field can be more favourable than the oscillating one. The goal of this work is to incorporate the presence of a static field and to perform a systematic study of the non-linear dynamics of the magnetisation in the framework of the deterministic Landau-Lifshitz-Gilbert equation in order to calculate energy losses. Two cases are considered: the static field is either assumed to be perpendicular to the plane of rotation or situated in the plane of rotation. In the latter case a significant increase in the energy loss/cycle is observed if the magnitudes of the static and the rotating fields have a certain ratio (e.g. it should be one for isotropic nanoparticles). It can be used to "super-localise" the heat transfer: in case of an inhomogeneous applied static field, tissues are heated up only where the magnitudes of the static and rotating fields reach the required ratio.

Dynamics of superparamagnetic nanoparticle in viscous liquid in rotating magnetic field

“…In this paper, the dynamics of a superparamagnetic nanoparticle in a viscous fluid in RMF is studied using both numerical simulation and analytical calculations. This topic has recently attracted considerable interest [33][34][35][36][37][38][39][40][41][42][43] in view of the possibility of using magnetic nanoparticles in magnetic hyperthermia for the cancer treatment. Unfortunately, in experiments [41,43] very small SAR values, of the order of several watts per gram, have been measured in RMF for assembly of superparamagnetic nanoparticles distributed in a viscous liquid.…”

“…Recently, the application of a rotating magnetic field (RMF) in biomedicine, in particular in magnetic hyperthermia, has been studied both theoretically [33][34][35][36][37][38][39] and experimentally [40][41][42][43].…”

Possibilities and Limitations of Different Separation Techniques for the Analysis of the Protein Corona

“…Another simple separation method for the isolation of the protein corona can be applied for the class of magnetic nanocarriers.I ng eneral, magnetic materials are interesting for certain applications in nanomedicine;f or example,t o direct nanocarriers to and focus them on atarget region by an outer magnetic field [25][26][27] or to kill cancer cells by magnetically induced hyperthermia. [28,29] Moreover,m agnetism can be exploited for the separation of the nanocarrier-protein complex from the excess biological medium, where different separation set-ups are possible.T he basic separation is achieved by bringing am agnet into close proximity to the sample and removing the supernatant as long as the nanoparticles are concentrated near the magnet, similar to pellet formation. After re-suspension in buffer, the procedure is repeated to wash the sample.O verall, the applied steps to obtain the corona via magnetism are similar to those for the centrifugation process and further analysis can be applied subsequently.P rotein corona analysis following magnetic separation-for example,i dentification of the adsorbed proteins by LC-MS-has already been done,a lthough without obtaining any information about the binding affinities of the proteins that were present.…”

Möglichkeiten und Limitierungen verschiedener Trenntechniken zur Analyse der Proteinkorona

“…B. um Nanoträger durch ein äußeres Magnetfeld auf ein Zielgebiet zu fokussieren [25][26][27] oder Krebszellen durch magnetisch induzierte Hyperthermie abzutçten. [28,29] [32] Auch Sakulkuh et al [33,34] machten eine klare Aussage,indem sie spezifizierten, dass in dem von ihnen getesteten System ausschließlich die harte Korona isoliert wurde.Sie verglichen die harte Korona von superparamagnetischen Eisenoxid-Nanoträgern (SPIONs) in Rattenplasma in vitro und in vivo und fanden heraus,d ass sich die Korona je nach Probenvorbereitung signifikant unterscheidet. [33] Zusätzlich wurden verschiedene Oberflächenfunktionalisierungend er SPI-ONs [34] Durch die magnetische Tr ennung wird ein allgemein vielseitiges Verfahren bereitgestellt, das jedoch auf bestimmte Materialien beschränkt ist und nicht als allgemeines Verfahren angewendet werden kann.…”