Effect of magnetic dipolar interactions on nanoparticle heating efficiency: Implications for cancer hyperthermia

Abstract

Nanostructured magnetic systems have many applications, including potential use in cancer therapy deriving from their ability to heat in alternating magnetic fields. In this work we explore the influence of particle chain formation on the normalized heating properties, or specific loss power (SLP) of both low- (spherical) and high- (parallelepiped) anisotropy ferrite-based magnetic fluids. Analysis of ferromagnetic resonance (FMR) data shows that high particle concentrations correlate with increasing chain length producing decreasing SLP. Monte Carlo simulations corroborate the FMR results. We propose a theoretical model describing dipole interactions valid for the linear response regime to explain the observed trends. This model predicts optimum particle sizes for hyperthermia to about 30% smaller than those previously predicted, depending on the nanoparticle parameters and chain size. Also, optimum chain lengths depended on nanoparticle surface-to-surface distance. Our results might have important implications to cancer treatment and could motivate new strategies to optimize magnetic hyperthermia.

Reduction of T2 Relaxation Rates due to Large Volume Fractions of Magnetic Nanoparticles for All Motional Regimes

“…Understanding not only the individual evolution of these parameters with scale, magnetic field, temperature, but also their interaction, mutual and with the surrounding environment, is of paramount importance to the design and application of intelligent and multifunctional magnetic nanoparticles (MNP). In biomedicine, MNPs and in particular superparamagnetic iron oxides (SPIO) have a wide range of applications such as magnetic particle imaging (MPI) [6], drug delivery [7], magnetic hyperthermia (MH) [8][9][10], MRI [11], cell tracking [12,13], magnetic biosensors [14,15], regenerative medicine and tissue engineering [16,17], etc. When used as MRI contrast agents (CA) SPIOs can reduce both T 1 and T 2 relaxation times and hence enhance tissue contrast [18][19][20][21].…”

Aggregation phenomena of a magnetic particle suspension in an alternating magnetic field and the influence on the heat generation effect (Brownian dynamics simulations)

“…性粒子間の相互作用の影響 (Burrows et al, 2010, Haase and Nowak, 2012, Martinez-Boubeta et al, 2012, Branquinho et al, 2013, Tan et al, 2014, Conde-Leboran et al, 2015a, 磁性粒子の配向が及ぼす影響 (Conde-Leboran et al, 2015b)， 振動磁場下で生じる磁性粒子の凝集体形成による発熱効果の実験的研究 (Serantes et al, 2010, Lima et al, 2013, Mehdaoui et al, 2013, Saville et al, 2014, Guibert et al, 2015などの種々のアプローチがなされている．最後の凝集体形 …”

Remote Hyperthermia, Drug Delivery and Thermometry: The Multifunctional Platform Provided by Nanoparticles

“…The literature reports on the observation of the hyperthermia effect while using AC magnetic fields with amplitudes and frequencies below 0.1 T and 1 kHz, respectively [85,86]. Particularly interesting is the modulation of the heat dissipation as isolated nanoparticles bind together to build in chain-like structures [87]. The physical picture of the magnetohyperthermia effect can be assessed by looking at the interaction between the nanoparticle's magnetic moment and the applied AC magnetic field.…”

“…Figure 1c shows the trend of the SAR mag while increasing the concentration of the magnetic sites per unit volume (φ). Worth mentioning the key combination of frequency (f) and magnetic field amplitude (H o ) into the parameter fH o 2 as the increase of φ may lead to the onset of magnetic chain-like structures, thus affecting the thermal dissipation remarkably [87]. Figure 1d shows the trend of the optical specific absorption rate (SAR opt ) as a function of the number of metallic nanoparticles per unit volume (N) at increasing values of the light source fluence (F) [53].…”