Specific absorption rate dependence on temperature in magnetic field hyperthermia measured by dynamic hysteresis losses (ac magnetometry)

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

doi:10.1088/0957-4484/26/1/015704

Cited by 91 publications

(82 citation statements)

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“…A value SAR=94±1 W/g was found from the initial slope of the temperature profile within the first 3 sec of AMF application (supporting information). In previous work containing extensive magnetic characterization, we showed that this sample has a SAR verifying the linear response theory based on Néel and Brown relaxation processes of the magnetic moments, using independent magnetic measurements of the specific magnetization and of the magnetic anisotropy constant [18].…”

Section: Mtn Synthesis and Characterizationsupporting

confidence: 74%

“…In this work, MNPs were synthesized by alkaline co-precipitation of ferrous and ferric salts followed by size sorting procedure as previously described [18]. Briefly, magnetite (Fe3O4) MNPs right after the co-precipitation reaction were totally oxidized into maghemite (γ-Fe2O3) by boiling ferric nitrate [19] and dispersed in dilute nitric acid.…”

Section: Mtn Synthesis and Characterizationmentioning

confidence: 99%

“…Then they were submitted to a size-sorting procedure based on the liquid-liquid phase-separation obtained by screening the electrostatic repulsions with an excess of electrolyte (HNO3) concentration, yet below 0.4 M (pH>0.4) in order to prevent MNP dissolution into ions. The principle of this sorting is that the concentrated phase is enriched with the larger NPs, whereas the dilute phase contains the smaller MNPs [18,20,21]. After repeating several phase separation and washing steps (three cycles), the sample named C1C2C3 originated from the concentrated phase fractions corresponding to the concentrated phases obtained by adding HNO3 electrolyte to the preceding pelleted fractions.…”

Section: Mtn Synthesis and Characterizationmentioning

confidence: 99%

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In Vivo Imaging of Local Gene Expression Induced by Magnetic Hyperthermia

Sandre¹,

Genevois²,

Garaio³

et al. 2017

Preprint

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Abstract:The present work aims to demonstrate that colloidal dispersions of magnetic iron oxide nanoparticles stabilized with dextran macromolecules placed in an alternating magnetic field can not only produce heat, but also that these particles could be used in vivo for local and non-invasive deposition of a thermal dose sufficient to trigger thermo-induced gene expression. Iron oxide nanoparticles were first characterized in vitro on a bio-inspired setup, and then they were assayed in vivo using a transgenic mouse strain expressing the luciferase reporter gene under transcriptional control of a thermosensitive promoter. Iron oxide nanoparticles dispersions were applied topically on the mouse skin or injected sub-cutaneously with Matrigel™ to generate so called pseudo tumors. Temperature was monitored continuously with a feedback loop to control the power of the magnetic field generator and to avoid overheating. Thermo-induced luciferase expression was followed by bioluminescence imaging 6 hours after heating. We showed that dextran-coated magnetic iron oxide nanoparticles dispersions were able to induce in vivo mild hyperthermia compatible with thermo-induced gene expression in surrounding tissues and without impairing cell viability. These data open new therapeutic perspectives for using mild magnetic hyperthermia as non-invasive modulation of tumor microenvironment by local thermo-induced gene expression or drug release.

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Section: Mtn Synthesis and Characterizationsupporting

confidence: 74%

Section: Mtn Synthesis and Characterizationmentioning

confidence: 99%

Section: Mtn Synthesis and Characterizationmentioning

confidence: 99%

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In Vivo Imaging of Local Gene Expression Induced by Magnetic Hyperthermia

Sandre¹,

Genevois²,

Garaio³

et al. 2017

Preprint

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“…19,20 This method permits precise and quick SAR measurements, allowing multi-parametric study for different frequencies, field intensities, and as a function of temperature. 21,22 Using the fundamentals and advantages of this last technique, we propose here an accurate, simple, and fast method for monitoring and controlling the temperature of magnetic nanoparticles during magnetic hyperthermia. The method does not need any additional probe or sensor attached to the magnetic nanoparticles.…”

mentioning

confidence: 99%

“…21,22,26 This thermal dependence is the direct result of the variation with temperature of the phase between magnetization M and applied magnetic field H. Hence, one can deduce that the harmonic phases of magnetization signal must vary with temperature as well. Therefore, the harmonic spectrum of the magnetization of water dispersed maghemite sample was measured when varying temperature from 30 to 50 C at different field frequencies (75, 302, 676, and 1030 kHz) and intensities (5,10,20, and 25 kA m À1 ).…”

mentioning

confidence: 99%

Harmonic phases of the nanoparticle magnetization: An intrinsic temperature probe

Garaio¹,

Collantes²,

Garcı́a

et al. 2015

Applied Physics Letters

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International audienceMagnetic fluid hyperthermia is a promising cancer therapy in which magnetic nanoparticles act as heat sources activated by an external AC magnetic field. The nanoparticles, located near or inside the tumor, absorb energy from the magnetic field and then heat up the cancerous tissues. During the hyperthermia treatment, it is crucial to control the temperature of different tissues: too high temperature can cause undesired damage in healthy tissues through an uncontrolled necrosis. However, the current thermometry in magnetic hyperthermia presents some important technical problems. The widely used optical fiber thermometers only provide the temperature in a discrete set of spatial points. Moreover, surgery is required to locate these probes in the correct place. In this scope, we propose here a method to measure the temperature of a magnetic sample. The approach relies on the intrinsic properties of the magnetic nanoparticles because it is based on monitoring the thermal dependence of the high order harmonic phases of the nanoparticle dynamic magnetization. The method is non-invasive and it does not need any additional probe or sensor attached to the magnetic nanoparticles. Moreover, this method has the potential to be used together with the magnetic particle imaging technique to map the spatial distribution of the temperature. (C) 2015 AIP Publishing LLC

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Using kinetic Monte Carlo simulations to design efficient magnetic nanoparticles for clinical hyperthermia

et al. 2021

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The purpose of this study was to identify the properties of magnetite nanoparticles that deliver optimal heating efficiency, predict the geometrical characteristics to get these target properties, and determine the concentrations of nanoparticles required to optimize thermotherapy. Methods: Kinetic Monte Carlo simulations were employed to identify the properties of magnetic nanoparticles that deliver high Specific Absorption Rate (SAR) values. Optimal volumes were determined for anisotropies ranging between 11 and 40 kJ/m 3 under clinically relevant magnetic field conditions. Atomistic spin simulations were employed to determine the aspect ratios of ellipsoidal magnetite nanoparticles that deliver the target properties. A numerical model was developed using the extended cardiac-torso (XCAT) phantom to simulate lowfield (4 kA/m) and high-field (18 kA/m) prostate cancer thermotherapy. A stationary optimization study exploiting the Method of Moving Asymptotes (MMA) was carried out to calculate the concentration fields that deliver homogenous temperature distributions within target thermotherapy range constrained by the optimization objective function. A time-dependent study was used to compute the thermal dose of a 30-min session. Results: Prolate ellipsoidal magnetite nanoparticles with a volume of 3922 ± 35 nm 3 and aspect ratio of 1.56, which yields an effective anisotropy of 20 kJ/m 3 , constituted the optimal design at current maximum clinical field properties (H 0 = 18 kA/m, f = 100 kHz), with SAR = 342.0 ± 2.7 W/g, while nanoparticles with a volume of 4147 ± 36 nm 3 , aspect ratio of 1.29, and effective anisotropy 11 kJ/m 3 were optimal for low-field applications (H 0 = 4 kA/m, f = 100 kHz), with SAR = 50.2 ± 0.5 W/g. The average concentration of 3.86 ± 0.10 and 0.57 ± 0.01 mg/cm 3 at 4 and 18 kA/m, respectively, were sufficient to reach therapeutic temperatures of 42-44 • C throughout the prostate volume. The thermal dose delivered during a 30-min session exceeded 5.8 Cumulative Equivalent Minutes at 43 • C within 90% of the prostate volume (CEM43T 90 ). Conclusion:The optimal properties and design specifications of magnetite nanoparticles vary with magnetic field properties. Application-specific magnetic nanoparticles or nanoparticles that are optimized at low fields are indicated for optimal thermal dose delivery at low concentrations.

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Specific absorption rate dependence on temperature in magnetic field hyperthermia measured by dynamic hysteresis losses (ac magnetometry)

Cited by 91 publications

References 50 publications

In Vivo Imaging of Local Gene Expression Induced by Magnetic Hyperthermia

In Vivo Imaging of Local Gene Expression Induced by Magnetic Hyperthermia

Harmonic phases of the nanoparticle magnetization: An intrinsic temperature probe

Using kinetic Monte Carlo simulations to design efficient magnetic nanoparticles for clinical hyperthermia

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