scholarly journals Towards Optimal Thermal Distribution in Magnetic Hyperthermia

2021 ◽  
Author(s):  
R. A. Rytov ◽  
V. A. Bautin ◽  
N. A. Usov
Keyword(s):  
Absorption Rate ◽  
Iron Nanoparticles ◽  
Specific Absorption Rate ◽  
Spatial Location ◽  
Dipole Interaction ◽  
Magnetic Hyperthermia ◽  
Spherically Symmetric ◽  
Heat Sources ◽  
Thermal Distribution ◽  
Suitable Temperature

Abstract A linear combination of spherically symmetric heat sources is shown to provide optimal stationary thermal distribution in magnetic hyperthermia. Furthermore, such spatial location of heat sources produces suitable temperature distribution in biological medium even for assemblies of magnetic nanoparticles with a moderate value of specific absorption rate (SAR), of the order of 100 - 150 W/g. We also demonstrate the advantage of using assemblies of magnetic nanocapsules consisting of metallic iron nanoparticles covered with non magnetic shells of sufficient thickness in magnetic hyperthermia. Based on numerical simulation we optimize the size and geometric structure of biocompatible capsules in order to minimize the influence of strong magneto-dipole interaction between closely spaced nanoparticles. It is shown that assembly of capsules can provide sufficiently high SAR values of the order of 250 - 400 W/g at moderate amplitudes H0·= 50 - 100 Oe and frequencies f = 100 - 200 kHz of alternating magnetic field, being appropriate for application in clinics.

scholarly journals Application of Magnetosomes in Magnetic Hyperthermia

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1320 ◽  
Author(s):  
Nikolai A. Usov ◽  
Elizaveta M. Gubanova
Keyword(s):  
Magnetic Field ◽  
Specific Absorption Rate ◽  
Magnetotactic Bacteria ◽  
Dipole Interaction ◽  
Magnetic Hyperthermia ◽  
Small Magnetic Field ◽  
Lifshitz Equation ◽  
Chain Axis ◽  
Rectangular Hysteresis Loop ◽  
A Chain

Nanoparticles, specifically magnetosomes, synthesized in nature by magnetotactic bacteria, are very promising to be usedin magnetic hyperthermia in cancer treatment. In this work, using the solution of the stochastic Landau–Lifshitz equation, we calculate the specific absorption rate (SAR) in an alternating (AC) magnetic field of assemblies of magnetosome chains depending on the particle size D, the distance between particles in a chain a, and the angle of the applied magnetic field with respect to the chain axis. The dependence of SAR on the a/D ratio is shown to have a bell-shaped form with a pronounced maximum. For a dilute oriented chain assembly with optimally chosen a/D ratio, a strong magneto-dipole interaction between the chain particles leads to an almost rectangular hysteresis loop, and to large SAR values in the order of 400–450 W/g at moderate frequencies f = 300 kHz and small magnetic field amplitudes H0 = 50–100 Oe. The maximum SAR value only weakly depends on the diameter of the nanoparticles and the length of the chain. However, a significant decrease in SAR occurs in a dense chain assembly due to the strong magneto-dipole interaction of nanoparticles of different chains.

scholarly journals The Effect of Tissue-Mimicking Phantom Compressibility on Magnetic Hyperthermia

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 803 ◽  
Author(s):  
Katarzyna Kaczmarek ◽  
Radosław Mrówczyński ◽  
Tomasz Hornowski ◽  
Rafał Bielas ◽  
Arkadiusz Józefczak
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Magnetic Materials ◽  
Absorption Rate ◽  
Magnetic Particles ◽  
Specific Absorption Rate ◽  
Magnetic Hyperthermia ◽  
Magnetic Losses ◽  
Small Temperature ◽  
Transmission Electron

During hyperthermia, magnetite nanoparticles placed in an AC magnetic field become a source of heat. It has been shown that in fluid suspensions, magnetic particles move freely and generate heat easily. However, in tissues of different mechanical properties, nanoparticle movement is limited and leads to a small temperature rise in tissue. Therefore, it is crucial to conduct magnetic hyperthermia experiments in similar conditions to the human body. The effect of tissue-mimicking phantom compressibility on the effectiveness of magnetic hyperthermia was investigated on agar phantoms. Single and cluster nanoparticles were synthesized and used as magnetic materials. The prepared magnetic materials were characterized by transmission electron microscopy (TEM), and zeta potential measurements. Results show that tissue-mimicking phantom compressibility decreases with the concentration of agar. Moreover, the lower the compressibility, the lower the thermal effect of magnetic hyperthermia. Specific absorption rate (SAR) values also proved our assumption that tissue-mimicking phantom compressibility affects magnetic losses in the alternating magnetic field (AMF).

The formation of linear aggregates in magnetic hyperthermia: Implications on specific absorption rate and magnetic anisotropy

2014 ◽  
Vol 424 ◽  
pp. 141-151 ◽  
Author(s):  
Steven L. Saville ◽  
Bin Qi ◽  
Jonathon Baker ◽  
Roland Stone ◽  
Robert E. Camley ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Magnetic Hyperthermia ◽  
Specific Absorption

Development of an Algorithm for Predicting the Thermal Distribution by using CT Image and the Specific Absorption Rate

2018 ◽  
Vol 73 (10) ◽  
pp. 1584-1588 ◽  
Author(s):  
Jinho Hwang ◽  
Aeran Kim ◽  
Jina Kim ◽  
Yunji Seol ◽  
Taegeon Oh ◽  
...  
Keyword(s):  
Absorption Rate ◽  
Specific Absorption Rate ◽  
Ct Image ◽  
Specific Absorption ◽  
Thermal Distribution
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