Predicting size-dependent heating properties of magnetic iron-oxide nanoparticles from experiment and simulation
- In the innovative tumor treatment approach of magnetic fluid hyperthermia (MFH), magnetic nanoparticles (MNP) are accumulated at the tumor site and heated in a time-varying magnetic field to substantially damage the tumor (1). This tumor damage depends mainly on the rate and amount of heat delivered via the MNP locally, which is in turn governed by a multitude of variables including the applied field amplitude and frequency, particle size and size distribution. In this study, we compare measured heating rates of MNP with sizes ranging from 21 nm to 28 nm with those obtained from Monte Carlo simulations of non-equilibrium Langevin dynamics to predict particle sizes and field amplitude /frequency settings for optimized MFH within medically safe tolerances. We have synthesized monodisperse iron-oxide MNP via thermal decomposition, coated with poly(ethylene glycol) methyl ether amine (mPEG NH2) as reported in (2). Transmission electron microscopy analysis yielded core sizes (and log-normal distribution width) of 21.9 nm (0.04), 23.1 nm (0.05), 25.3 nm (0.08) and 27.7 nm (0.07). These MNP were subjected to magnetic fields with amplitudes h0 = (6...20) mT/ 0-1 and frequencies f = (176...993) kHz in a magneTherm hyperthermia device (nanoTherics Ltd., Newcastle under Lyme, UK). From the recorded timetemperature curves we calculated the specific loss power (SLP) as a measure of the heating rate: SLP values increased generally with size and frequency (Fig. 1a), as well as with the field amplitude (not shown here). Monte Carlo based stochastic Langevin equation simulations combining Néel and Brownian rotation relaxation and thermal activation (based on (3)) verified this trend (Fig. 1b). Under the assumption of an upper field limitation of f[kHz] · h0[mT/ 0-1] 1758 imposed by medical safety requirements (4), we simulated a heat map based on the parameters obtained from fitting simulation to experiment (Fig. 1c). This map shows maximum SLP values for frequencies f ~ 100 kHz (equivalent to h0 ~ 17.5 mT/ 0-1) at particle sizes of 29 nm and greater. These results can provide a pivotal and integral tool for predicting particle sizes and applied field settings for optimized MFH.
Author: | Ulrich M. EngelmannORCiD, Eric Teeman, Carolyn Shasha, Ioana Slabu, Kannan M. Krishnan |
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Parent Title (English): | 12th International Conference on the Scientific and Clinical Applications of Magnetic Carriers |
Document Type: | Conference Poster |
Language: | English |
Year of Completion: | 2018 |
First Page: | 52 |
Note: | 12th International Conference on the Scientific and Clinical Applications of Magnetic Carriers, Copenhagen, Denmark, May 22-26 2018 Poster 10 |
Note: | Corresponding author: Ulrich M. Engelmann |
Link: | https://magneticmicrosphere.com/ckfinder/userfiles/files/Magmeet2018AB.pdf |
Zugriffsart: | weltweit |
Institutes: | FH Aachen / Fachbereich Medizintechnik und Technomathematik |