Specific absorption rate of randomly oriented magnetic nanoparticles in a static magnetic field

• Ruslan A. Rytov and
• Nikolai A. Usov

Beilstein J. Nanotechnol. 2023, 14, 485–493, doi:10.3762/bjnano.14.39

• = 0–800 Oe. The specific absorption rate (SAR) of the assemblies is calculated depending on the angle between the directions of the ac and dc magnetic fields. For the case of an inhomogeneous dc magnetic field created by two opposite magnetic fluxes, the spatial distribution of the SAR in the vicinity

• hyperthermia; magnetic nanoparticles; magnetic particle imaging; specific absorption rate; static magnetic field; Introduction Magnetic nanoparticles, mainly iron oxides, are promising materials for the diagnosis and therapy of oncological diseases [1][2][3]. Important fields of application of magnetic

• amplitude, Hac = 100–200 Oe [1][7][8]. In magnetic hyperthermia, magnetic nanoparticles are introduced into the tumor and heated by absorbing the energy of the ac magnetic field. The intensity of heat release is characterized by the specific absorption rate (SAR) of an assembly. Maintaining a temperature in

Heating ability of elongated magnetic nanoparticles

• Elizaveta M. Gubanova,
• Nikolai A. Usov and
• Vladimir A. Oleinikov

Beilstein J. Nanotechnol. 2021, 12, 1404–1412, doi:10.3762/bjnano.12.104

• .12.104 Abstract Low-frequency hysteresis loops and specific absorption rate (SAR) of various assemblies of elongated spheroidal magnetite nanoparticles have been calculated for a range of particle semiaxis ratios a/b = 1.0–3.0. The SAR of a dilute randomly oriented assembly of magnetite nanoparticles in

• of magnitude with an increase in the volume fraction of nanoparticles in a cluster in the range of 0.04–0.2. Keywords: elongated magnetic nanoparticles; magnetic hyperthermia; numerical simulation; specific absorption rate; Introduction Magnetic nanoparticle assemblies have great potential for the

• cases this stops the tumor growth and results in its decay. However, it are magnetic nanoparticles with low toxicity and a high specific absorption rate (SAR) of the energy of the ac magnetic field that are needed in magnetic hyperthermia. The use of optimized assemblies of magnetic nanoparticles can

Dynamics of superparamagnetic nanoparticles in viscous liquids in rotating magnetic fields

• Nikolai A. Usov,
• Ruslan A. Rytov and
• Vasiliy A. Bautin

Beilstein J. Nanotechnol. 2019, 10, 2294–2303, doi:10.3762/bjnano.10.221

• director are distinguished depending on frequency and amplitude of the rotating magnetic field. The specific absorption rate of a dilute assembly of superparamagnetic nanoparticles in rotating magnetic field is calculated by solving the Landau–Lifshitz stochastic equation for the unit magnetization vector

• and the stochastic equation for the particle director. At elevated frequencies an optimal range of particle diameters is found where the specific absorption rate of an assembly in a rotating magnetic field has a maximum. It is shown that with an optimal choice of the particle sizes sufficiently large

• SAR values of the order of 400–500 W/g can be obtained in a rotating magnetic field with a frequency f = 400 kHz and a moderate magnetic field amplitude H0 = 100 Oe. Keywords: magnetic hyperthermia; magnetic nanoparticles; numerical simulation; rotating magnetic field; specific absorption rate

The effect of magneto-crystalline anisotropy on the properties of hard and soft magnetic ferrite nanoparticles

• Hajar Jalili,
• Bagher Aslibeiki,
• Ali Ghotbi Varzaneh and
• Volodymyr A. Chernenko

Beilstein J. Nanotechnol. 2019, 10, 1348–1359, doi:10.3762/bjnano.10.133

• to destroy cancer cells through the elevated temperatures [16][17]. The heating efficiency of the NPs as heat sources under ac magnetic fields is often denominated as specific absorption rate (SAR), which is directly related to the area of the magnetic hysteresis loop of the nanoparticles by the

• plots from linearity as well as the negative δm curves indicate a predominance of dipole–dipole interactions in all samples. It was observed that Co doping strongly reduces the specific absorption rate values (to about a fourth) in the samples, despite increasing the magnetic anisotropy, saturation

On the relaxation time of interacting superparamagnetic nanoparticles and implications for magnetic fluid hyperthermia

• Andrei Kuncser,
• Nicusor Iacob and
• Victor E. Kuncser

Beilstein J. Nanotechnol. 2019, 10, 1280–1289, doi:10.3762/bjnano.10.127

• superparamagnetic regime in the presence of interparticle dipolar interactions is considered. The direct implications of such interactions for magnetic fluid hyperthermia therapy through susceptibility loss mechanisms give rise to an indirect method for their study via specific absorption rate measurements

• superparamagnetic nanoparticles on the specific absorption rate of ferrofluids, through susceptibility loss mechanisms, are discussed. Various models supporting the influence of interparticle interactions on the relaxation time are reviewed, leading to the conclusion that they are controversial, not versatile

• enough, and are limited to particular cases. A more general perturbation approach of the simple Néel expression is introduced with both the relaxation time constant and the anisotropy energy barrier depending on interparticle interactions, as suggested by specific absorption rate measurements performed

Heating ability of magnetic nanoparticles with cubic and combined anisotropy

• Nikolai A. Usov,
• Mikhail S. Nesmeyanov,
• Elizaveta M. Gubanova and
• Natalia B. Epshtein

Beilstein J. Nanotechnol. 2019, 10, 305–314, doi:10.3762/bjnano.10.29

• , Moscow, Russia National Research Nuclear University “MEPhI”, 115409, Moscow, Russia 10.3762/bjnano.10.29 Abstract The low frequency hysteresis loops and specific absorption rate (SAR) of assemblies of magnetite nanoparticles with cubic anisotropy are calculated in the diameter range of D = 20–60 nm

• . However, the ability of magnetic nanoparticle assemblies to generate heat can be improved if the nanoparticles are covered by nonmagnetic shells of appreciable thickness. Keywords: fractal clusters; magnetite nanoparticles; magneto–dipole interaction; numerical simulation; specific absorption rate

• ] and sufficiently high saturation magnetization [5]. However, only nanoparticles with a high specific absorption rate (SAR) in an alternating external magnetic field are suitable for magnetic hyperthermia. Therefore, a significant number of recent experimental studies [6][7][8][9][10][11][12][13][14

Hybrid Au@alendronate nanoparticles as dual chemo-photothermal agent for combined cancer treatment

• Anouchka Plan Sangnier,
• Romain Aufaure,
• Laurence Motte,
• Claire Wilhelm,
• Erwann Guenin and
• Yoann Lalatonne

Beilstein J. Nanotechnol. 2018, 9, 2947–2952, doi:10.3762/bjnano.9.273

• concentration. Figure 2 shows the plateau temperatures reached after 5 min of irradiation (Figure 2a), as well as the concentration-normalized heating efficiency expressed as the specific absorption rate (SAR) in watts per gram of Au (Figure 2b, see also Supporting Information File 1 for calculation details and

Magnetic-Fe/Fe₃O₄-nanoparticle-bound SN38 as carboxylesterase-cleavable prodrug for the delivery to tumors within monocytes/macrophages

• Hongwang Wang,
• Tej B. Shrestha,
• Matthew T. Basel,
• Raj K. Dani,
• Gwi-Moon Seo,
• Sivasai Balivada,
• Marla M. Pyle,
• Heidy Prock,
• Olga B. Koper,
• Prem S. Thapa,
• David Moore,
• Ping Li,
• Viktor Chikan,
• Deryl L. Troyer and
• Stefan H. Bossmann

Beilstein J. Nanotechnol. 2012, 3, 444–455, doi:10.3762/bjnano.3.51

• mL of water to the alternating magnetic field (Supporting Information File 1, Figure S5). The specific absorption rate (SAR) is calculated to be 522 ± 40 W/g. We propose that the excellent heating capacity of magnetic nanoparticles is due to the presence of the Fe(0) core in this core/shell