The role of size polydispersity in magnetic fluid hyperthermia: average vs. local infra/over-heating effects

Abstract

An efficient and safe hyperthermia cancer treatment requires the accurate control of the heating performance of magnetic nanoparticles, which is directly related to their size. However, in any particle system the existence of some size polydispersity is experimentally unavoidable, which results in a different local heating output and consequently a different hyperthermia performance depending on the size of each particle. With the aim to shed some light on this significant issue, we have used a Monte Carlo technique to study the role of size polydispersity in heat dissipation at both the local (single particle) and global (macroscopic average) levels. We have systematically varied size polydispersity, temperature and interparticle dipolar interaction conditions, and evaluated local heating as a function of these parameters. Our results provide a simple guide on how to choose, for a given polydispersity degree, the more adequate average particle size so that the local variation in the released heat is kept within some limits that correspond to safety boundaries for the average-system hyperthermia performance. All together we believe that our results may help in the design of more effective magnetic hyperthermia applications.

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

“…Unfortunately, these approaches cannot be directly applied to predict or analyse the dynamic spectra of magnetic dipolar nanoparticle systems, as they lack an intrinsic feature of the latter, namely, particle polydispersity. The numerical work on hyperthermia, in which polydispersity was addressed, showed that the dispersion of the local heating can change a lot with the particle average size 72 . To this extent, earlier this year, we put forward a new theoretical approach 73 based on the analytical solution of the Fokker-Plank equation with an additional term allowing for the interparticle interactions and system polydispersity.…”

In-situ particles reorientation during magnetic hyperthermia application: Shape matters twice

“…Such distinction is illustrated by comparing the reversal processes of two different magnetic structures with single-domain configuration at remanence: a small spherical nanoparticle and a magnetic nanowire (NW). If the reversal process of the particle is via coherent rotation, the energy dissipated is proportional to the particle volume and anisotropy27; in the magnetic NW, however, the reversal is likely to occur via nucleation and propagation of a domain wall (DW)20, and in that case the energy dissipated is not proportional to the entire NW volume but only to that of the DW. For the present elongated particles, the additional anisotropy contribution due to ellipsoidal shape might promote the coherent-reversal behaviour even in larger sizes.…”

Specific Loss Power in Magnetic Hyperthermia: Comparison of Monodispersion and Polydispersion

“…We also presented a method for the estimation of the SLP in the presence of both the AMF and SMF [11], which was derived by solving the magnetization relaxation equation of Shliomis [12] numerically.In these studies, we assumed that the particle size distribution was monodisperse. As previously described, however, the existence of some size polydispersity of MNPs is experimentally unavoidable [13], [14]. Thus, in this study, we investigated the effect of the particle size polydispersity on the SLP in magnetic hyperthermia under various conditions of MNPs, AMF, and SMF.…”

“…Because not all particles in a certain volume have the same diameter Din the polydisperse case [13], [14], the SLP qss value calculated from Eq. 13should be averaged based on the particle size distribution as…”

“…Furthermore, we have also presented a method for estimating the SLP in the presence of both the AMF and SMF [11], which was based on the numerical solution of the magnetization relaxation equation of Shliomis [12].In our previous papers [8], [11], however, the particle size distribution was assumed to be monodisperse. As pointed out by Munoz-Menendez et al [13], [14], the existence of some size polydispersity of MNPs is experimentally unavoidable, resulting in a different hyperthermia performance depending on the size of each MNP. Thus, the size polydispersity of MNPs is one of the important issues to achieve an accurate control of the heating performance of MNPs.…”