A wide-frequency range AC magnetometer to measure the specific absorption rate in nanoparticles for magnetic hyperthermia

Garaio, Eneko; Collantes, J.M.; Garcı́a, J.A.; Plazaola, F.; Mornet, Stéphane; Couillaud, Franck; Sandre, Olivier

doi:10.1016/j.jmmm.2013.11.021

Cited by 94 publications

(78 citation statements)

References 30 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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“…The time-evolution response of magnetization is an important feature that indicates the mechanisms of magnetic relaxation. In previous studies, AC hysteresis loops have been measured at frequencies of 394 and 785 kHz or in the frequency range extending down to 1 kHz [10,11]. In addition, the influences of the MNP concentration and viscosity on heat dissipation have been evaluated using AC hysteresis loops [11,12].…”

Section: Introductionmentioning

confidence: 99%

Rotation of Magnetization Derived from Brownian Relaxation in Magnetic Fluids of Different Viscosity Evaluated by Dynamic Hysteresis Measurements over a Wide Frequency Range

et al. 2016

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The dependence of magnetic relaxation on particle parameters, such as the size and anisotropy, has been conventionally discussed. In addition, the influences of external conditions, such as the intensity and frequency of the applied field, the surrounding viscosity, and the temperature on the magnetic relaxation have been researched. According to one of the basic theories regarding magnetic relaxation, the faster type of relaxation dominates the process. However, in this study, we reveal that Brownian and Néel relaxations coexist and that Brownian relaxation can occur after Néel relaxation despite having a longer relaxation time. To understand the mechanisms of Brownian rotation, alternating current (AC) hysteresis loops were measured in magnetic fluids of different viscosities. These loops conveyed the amplitude and phase delay of the magnetization. In addition, the intrinsic loss power (ILP) was calculated using the area of the AC hysteresis loops. The ILP also showed the magnetization response regarding the magnetic relaxation over a wide frequency range. To develop biomedical applications of magnetic nanoparticles, such as hyperthermia and magnetic particle imaging, it is necessary to understand the mechanisms of magnetic relaxation.

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“…However, because of the technology used for the production of the AMF, the maximum AMF amplitude was only 19 mT and the coil had to be water cooled. Finally, a setup with similar functionalities as the one which will be presented here has been built by Garaio et al [10]. Unfortunately, very few technical and building details are provided in this reference, preventing anyone to envisage building a similar setup.…”

Section: Main Textmentioning

confidence: 99%