Mechanisms of hyperthermia in magnetic nanoparticles

Vallejo-Fernández, G.; Whear, Oliver; Roca, Alejandro G.; Hussain, Shahzad; Timmis, Jon; Patel, Vijay; O'Grady, K.

doi:10.1088/0022-3727/46/31/312001

Cited by 218 publications

(156 citation statements)

References 11 publications

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“…9 Despite attempts to repair LRT by adding field dependence to the relaxation time, 10 this simplified theory is unable to predict the non-elliptical shapes of experimentally observed hysteresis at high AMF amplitudes, 11 indicating the need for more general approaches. One alternative is to model coherent precession and reversal with the Landau-Lifshitz-Gilbert equation, incorporating a fictitious stochastically varying thermal field in addition to the effective field.…”

Section: Textmentioning

confidence: 99%

Magnetically multiplexed heating of single domain nanoparticles

Christiansen

Senko

Chen

et al. 2014

Applied Physics Letters

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Abstract:Selective hysteretic heating of multiple collocated sets of single domain magnetic nanoparticles (SDMNPs) by alternating magnetic fields (AMFs) may offer a useful tool for biomedical applications. The possibility of "magnetothermal multiplexing" has not yet been realized, in part due to prevalent use of linear response theory to model SDMNP heating in AMFs. Predictive successes of dynamic hysteresis (DH), a more generalized model for heat dissipation by SDMNPs, are observed experimentally with detailed calorimetry measurements performed at varied AMF amplitudes and frequencies. The DH model suggests that specific driving conditions play an underappreciated role in determining optimal material selection strategies for high heat dissipation. Motivated by this observation, magnetothermal multiplexing is theoretically predicted and empirically demonstrated for the first time by selecting SDMNPs with properties that suggest optimal hysteretic heat dissipation at dissimilar AMF driving conditions. This form of multiplexing could effectively create multiple channels for minimally invasive biological signaling applications. Text:Magnetic fields provide a convenient form of noninvasive electronically driven stimulus that can reach deep into the body because of the weak magnetic properties and low conductivity of tissue. Single domain magnetic nanoparticles (SDMNPs) may act as transducers of heat for such remote stimulation in the presence of an alternating magnetic field (AMF).1, 2 Despite decades of research, biological applications of magnetically induced heat dissipation remain limited to remote activation of individual processes such as controlled cell death 3 or, more recently, initiation of a single biochemical pathway. 4,5 Many biomedical applications would benefit from the capability to independently and remotely control multiple pathways or cell types in close spatial proximity through selectively heating particle sets with differing magnetic properties by varying the driving conditions of the AMF.The possibility for such multiplexed magnetic heating has not yet been demonstrated, in part because it relies upon recognizing the influence of the applied AMF on stochastic magnetization reversal. Though such a)

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Section: Textmentioning

confidence: 99%

Magnetically multiplexed heating of single domain nanoparticles

Christiansen

Senko

Chen

et al. 2014

Applied Physics Letters

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“…One of these new techniques is the so-called magnetic hyperthermia [5], [6]. The energy comes from a radio frequency source of some hundreds of kilohertz and consequently, nanoparticles of ferromagnetic materials (some tenths of nanometers) are used as the intermediate agents.…”

Section: Introductionmentioning

confidence: 99%

Development and Testing of a New Instrument for Researching on Cancer Treatment Technologies Based on Magnetic Hyperthermia

García

Moreno-Arrones

Cuesta

et al. 2016

IEEE J. Emerg. Sel. Topics Power Electron.

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Abstract-A power electronics circuit allows the generation of high-frequency magnetic field that can be used to increase the temperature of cancer cells previously invaded with the magnetic nanoparticles. The circuit designed for this purpose is a high-frequency phase-shift inverter implemented with SiC devices and natural zero voltage switching. The inductive load has been optimized to increase as much as possible the magnetic field at the center of it considering the physical restrictions. Into this inductor, an adiabatic probe filled with nanoparticles is placed being the main objective to increase its temperature. The control of the inverter has been designed in such a way that it is easy to try waveforms different from the classical sine waves to see its effect on the temperature of the sample. Although the research is in one of the early stages, the first conclusions about the optimal frequency and field have been obtained showing that this technique could be a real option in the future.

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“…The SAR is expressed as the heat released by the magnetic iron oxide nanoparticles subjected to the magnetic field. Its value was calculated from the formula [27]:…”

Section: Resultsmentioning

confidence: 99%

Positron Annihilation in Magnetite Nanopowders Prepared by Co-Precipitation Method

et al. 2017

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Nanosized iron oxide powders are materials considered with regard to its application in medical therapy called hyperthermia. Magnetite nanopowders with crystallite size varying from 6.6 to 11.8 nm have been prepared by the co-precipitation method. In this study a change of a crystallite size is driven mainly by varying of initial pH of water ammonia solution in which a process of magnetite precipitation runs. Crystallographic structures and phase composition obtained samples and the size of magnetite nanoparticles were determined by X-ray diffraction method. Positron lifetime spectroscopy has been used to assess defectiveness of microstructure. Experimental positron annihilation spectra were successfully resolved into three lifetime components. It appears that from point of view of microstructure the defects concentrations in studied nanopowder samples are very high which causes a saturation of positron trapping.

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Mechanisms of hyperthermia in magnetic nanoparticles

Cited by 218 publications

References 11 publications

Magnetically multiplexed heating of single domain nanoparticles

Magnetically multiplexed heating of single domain nanoparticles

Development and Testing of a New Instrument for Researching on Cancer Treatment Technologies Based on Magnetic Hyperthermia

Positron Annihilation in Magnetite Nanopowders Prepared by Co-Precipitation Method

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