Susceptibility losses in heating of magnetic core/shell nanoparticles for hyperthermia: a Monte Carlo study of shape and size effects

Abstract

Optimizing the heating properties of magnetic nanoparticles is of great importance for hyperthermia applications. Recent experimental results show that core/shell nanoparticles could give an increased specific absorption rate (SAR) compared to the magnetic oxide nanoparticles currently used. We have developed a modified phenomenological model based on the linear Néel-Brown relaxation model to calculate the SAR due to susceptibility losses in complex nanoparticles with ferromagnetic (FM) core/ferrimagnetic (FiM) shell morphology. We use the Monte Carlo (MC) simulation technique with the implementation of the Metropolis algorithm to investigate the effect of size and shape on the magnetisation behaviour of complex ferromagnetic/ferrimagnetic nanoparticles covered by a surfactant layer. The findings of our simulations are used as an input in our modified model for the calculation of the SAR. Our calculations show that for all the sizes and shapes the complex FM/FiM nanoparticles give higher SAR values than the pure ferrimagnetic ones due to their higher core saturation magnetisation. For all sizes the nanoparticles with the truncated cuboctahedral shape give the highest SAR values and the cubic ones the lowest ones. The decrease in the surfactant thickness results in an increase of the SAR values. Our results have the same characteristics as the available experimental data from Fe/Fe3O4 nanoparticles, confirming that the complex nanoparticles with core/shell morphology can optimise the heating properties for hyperthermia.

The influence of interparticle correlations and self-assembly on the dynamic initial magnetic susceptibility spectra of ferrofluids

“…The influence of magnetic dipolar interactions on the specific absorption rate leads to a decrease or an increase in the hypothermia efficiency depending on the magnetic particle size [10][11][12]. This observation has been confirmed in other investigations [13,14] and it is clear that interparticle correlations should be taken into account when predicting the dynamic susceptibility spectra of magnetic nanoparticles. Until recently, though, a theoretical formalism to allow for correlations was missing.…”

Temperature-dependent dynamic correlations in suspensions of magnetic nanoparticles in a broad range of concentrations: a combined experimental and theoretical study

“…This result together with the results of study 69 underline the crucial part of polydispersity and interactions on the dynamic magnetic response and specific absorption rate. In general, it was shown both in simulations and experiment that complex nanoparticles with ferromagnetic core and ferrimagnetic shell morphology can enhance the efficiency of hyperthermia 70 . Another combined theoretical-experimental investigation of the hyperthermia was recently carried out on the level of mean-field for the model core-shell particle 71 .…”

Stimuli‐Responsive Release of Antimicrobials Using Hybrid Inorganic Nanoparticle‐Associated Drug‐Delivery Systems

“…During magnetothermal heating, the alternating magnetic field produces a phase lag between the applied field and the NP magnetization creating a hysteresis loop. The excess energy of the hysteresis is thermally emitted through changes in spin state and through the induced rotation causing friction between the particle and the surrounding fluid, mechanisms known as Néel and Brownian relaxations, respectively …”

“…The excess energy of the hysteresis is thermally emitted through changes in spin state and through the induced rotation causing friction between the particle and the surrounding fluid, mechanisms known as Néel and Brownian relaxations, respectively. [79] Mohapatra and co-workers used chitosan-based microbeads loaded with magnetite SPIONs to demonstrate the on-demand release of vancomycin. [78] In this system, the SPIONs were incorporated during the microbead formation, which involves the cross-linking of chitosan and vancomycin to poly(ethylene glycol) dimethacrylate (PEGDMA) via Michael addition.…”