Understanding mNP hyperthermia for cancer treatment at the cellular scale

Abstract

The use of magnetic nanoparticles (mNP’s) to induce local hyperthermia has been emerging in recent years as a promising cancer therapy, in both a stand-alone and combination treatment setting. Studies have shown that cancer cells associate with, internalize, and aggregate mNP’s more preferentially than normal cells. Once the mNP’s are delivered inside the cells, a low frequency (30 kHz–300 kHz) alternating electromagnetic field is used to activate the mNP’s. The nanoparticles absorb the applied field and provide localized heat generation at nano-micron scales. It has been shown experimentally that mNP’s exhibit collective behavior when in close proximity. Although most prevailing mNP heating models assume there is no magnetic interaction between particles, our data suggests that magnetic interaction effects due to mNP aggregation are often significant; In the case of multi-crystal core particles, interaction is guaranteed. To understand the physical phenomena responsible for this effect, we modeled electromagnetic coupling between mNP’s in detail. The computational results are validated using data from the literature as well as measurements obtained in our lab. The computational model presented here is based on a method of moments technique and is used to calculate magnetic field distributions on the nanometer scale, both inside and outside the mNP.

Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy

“…The absence of the hysteresis loop for MNPs in solution could also be related to their free whole rotation by the applied field in colloids. However, some MNPs exhibit hysteresis in colloidal solutions, 22,69 which are due to magnetic interactions between MNPs. These interactions have a significant role in understand the magnetic properties of the dry, packed MNPs.…”

“…This computational model has also been applied to Micromod BNF type particles. 69 To further understand the interactions between the MNPs, we modeled the electromagnetic (EM) field behavior between the MNPs.…”

Mitigation of eddy current heating during magnetic nanoparticle hyperthermia therapy

“…Additionally, the SAR due to MNP is estimated by using the computed magnetic fields and MNP distributions. The total SAR is calculated as, $$\text{italicSAR}={\mathit{\text{SAR}}}_{\mathit{\text{EC}}}+{\mathit{\text{SAR}}}_{\mathit{\text{MNP}}}$$ where, SAR MNP is determined using the MNP heating model discussed in [35, 65]. Finally, the total SAR distribution and thermal boundary conditions are fed into the Pennes Bioheat Equation [66, 67] which is solved using a standard finite difference time domain method [68–70].…”

Magnetic Composite Biomaterials for Neural Regeneration

“…If the field stimulation is dynamic, the stimulation frequency can have varying effects as well. For example, higher frequencies (30–300 kHz) are used for cancer hyperthermia, where stimulation of MNPs generates localized heating to kill tumor cells (Stigliano et al, 2013). In contrast, lower frequencies (<100 Hz) have been shown to activate mechanosenstive ion channels and promote cell growth (Hughes et al, 2005).…”