Magnetic particle hyperthermia: nanoparticle magnetism and materials development for cancer therapy

Abstract

Loss processes in magnetic nanoparticles are discussed with respect to optimization of the specific loss power (SLP) for application in tumour hyperthermia. Several types of magnetic iron oxide nanoparticles representative for different preparation methods (wet chemical precipitation, grinding, bacterial synthesis, magnetic size fractionation) are the subject of a comparative study of structural and magnetic properties. Since the specific loss power useful for hyperthermia is restricted by serious limitations of the alternating field amplitude and frequency, the effects of the latter are investigated experimentally in detail. The dependence of the SLP on the mean particle size is studied over a broad size range from superparamagnetic up to multidomain particles, and guidelines for achieving large SLP under the constraints valid for the field parameters are derived. Particles with the mean size of 18 nm having a narrow size distribution proved particularly useful. In particular, very high heating power may be delivered by bacterial magnetosomes, the best sample of which showed nearly 1 kW g −1 at 410 kHz and 10 kA m −1. This value may even be exceeded by metallic magnetic particles, as indicated by measurements on cobalt particles.

Relaxometry and Dephasing Imaging of Superparamagnetic Magnetite Nanoparticles Using a Single Qubit

“…Assuming a net magnetic moment of 4 μB per formula unit (Fe3O4) as is typically calculated for magnetite and taking the density of magnetite to be 5.175 g/cm 3 , this magnetic moment density turns out to be 5.4·10 28 μB/m 3 . 25 Integration over the particle's volume yields the total magnetic field ⃗⃗ = ⃗ ⃗⃗ 0 4 3 (− sin cos , − cos sin , −2 cos ),…”

Influence of dipolar interactions on hyperthermia properties of ferromagnetic particles

“…It appears that increasing concentration reduces the magnetic hysteresis due to dipolar coupling effects, as has also been suggested in previous works reporting similar SAR versus magnetic field evolution. 11,23 However, the cause of such decrease remains still unclear, being also conjectured to originate from a broad size distribution. Thus, with the purpose of studying the role of magnetic dipolar interactions on the hyperthermia proper- ties of the NP system, we performed MC simulations to treat the influence of particle concentration and field dependence on the SAR.…”

Chains of Magnetosomes Extracted from AMB-1 Magnetotactic Bacteria for Application in Alternative Magnetic Field Cancer Therapy

“…In part due to their large volume, the magnetosomes synthesized by magnetotactic bacteria produce a larger amount of heat than the chemically synthesized nanoparticles when they are exposed to an oscillating magnetic field. This has been shown for bacterial magnetosomes mixed in solution, which were either contained within the magnetotactic bacteria or extracted from these bacteria and for magnetosomes arranged in chains or forming individual nanoparticles, (6,12). In addition of producing a large amount of heat, it has been reported that the magnetosomes are not particularly toxic when they are injected in rats, (11).…”

“…The chemically synthesized nanoparticles (SPION@Citrate) were prepared following a protocol described previously, (14). To prepare non-coated γFe2O3 particles, a solution of base (dimethylamine) was first added to an aqueous micellar solution of ferrous dodecyl sulfate (Fe(DS)2) and mixed.…”