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3 results on '"Neel relaxation time"'

1. Adjusting the Néel relaxation time of Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles for optimal heat generation in magnetic hyperthermia

Author

Myriam H. Aguirre, Gerardo F. Goya, Alberto Ghirri, Horacio Esteban Troiani, Fernando Fabris, Marcelo Vasquez Mansilla, Emilio De Biasi, Javier Hernán Lohr, Elin L. Winkler, Enio Lima, Davide Peddis, Luis M. Rodríguez, Daniele Rinaldi, Dino Fiorani, Roberto D. Zysler, and Adriele Aparecida de Almeida

Subjects
Materials science, Neel relaxation time, Analytical chemistry, Shell (structure), Nanoparticle, Bioengineering, core/shell nanoparticles, magnetic fluid hyperthermia, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, shell nanoparticles, Viscosity, General Materials Science, el relaxation time, Electrical and Electronic Engineering, Mechanical Engineering, core, N&#233, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Magnetic anisotropy, Magnetic hyperthermia, Mechanics of Materials, Heat generation, Particle, Atomic ratio, 0210 nano-technology
Abstract

In this work it is shown a precise way to optimize the heat generation in high viscosity magnetic colloids, by adjusting the Neel relaxation time in core/shell bimagnetic nanoparticles, for Magnetic Fluid Hyperthermia applications. To pursue this goal, Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles were synthesized with 8.5 nm mean core diameter, encapsulated in a shell of ~1.1 nm of thickness, where the Zn atomic ratio (Zn/(Zn+Co) at%) changes from 33 at% to 68 at%. The magnetic measurements are consistent with a rigid interface coupling between the core and shell phases, where the effective magnetic anisotropy systematically decreases when the Zn concentration increases, without a significant change of the saturation magnetization. Experiments of magnetic fluid hyperthermia of 0.1 wt% of these particles dispersed in water, DMEM (Dulbecco modified Eagles minimal essential medium) and a high viscosity butter oil, result in a large specific loss power (SLP), up to 150 W/g, when the experiments are performed at 571 kHz and 200 Oe. The SLP was optimized adjusting the shell composition, showing a maximum for intermediate Zn concentration. This study shows a way to maximize the heat generation in viscous media like cytosol, for those biomedical applications that requiere smaller particle sizes .

Published
2020
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2. Quantitative Analysis of the Specific Absorption Rate Dependence on the Magnetic Field Strength in ZnxFe3−xO4 Nanoparticles

Author

M. Benaissa, Dris Ihiawakrim, Constantin Mihai Lucaciu, Walid Baaziz, Cristian Iacovita, Guillaume Rogez, Ovidiu Ersen, Mohamed Alae Ait Kerroum, Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Matériaux et nanosciences d'Alsace (FMNGE), Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Iuliu Hatieganu University of Medicine & Pharmacy, Laboratoire de Matière Condensée et Sciences Interdisciplinaires (LaMCScI), University of Mohammed V, Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et Nanosciences Grand-Est (MNGE), Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Université Mohammed V de Rabat [Agdal] (UM5), and Rogez, Guillaume

Subjects
Neel relaxation time, Analytical chemistry, Aucun, Metal Nanoparticles, 02 engineering and technology, 01 natural sciences, lcsh:Chemistry, X-Ray Diffraction, Spectroscopy, Fourier Transform Infrared, Saturation (magnetic), lcsh:QH301-705.5, Spectroscopy, Relaxation (NMR), Temperature, General Medicine, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 3. Good health, Computer Science Applications, Magnetic field, Zinc, specific absorption rate, Linear Response Theory, 0210 nano-technology, Superparamagnetism, Materials science, 010402 general chemistry, zinc doped iron oxide magnetic nanoparticles, Catalysis, Article, Citric Acid, Inorganic Chemistry, Magnetization, Microscopy, Electron, Transmission, magnetic hyperthermia, Physical and Theoretical Chemistry, Molecular Biology, [CHIM.MATE] Chemical Sciences/Material chemistry, saturation of SAR, co-precipitation method, Organic Chemistry, Spectrometry, X-Ray Emission, Hyperthermia, Induced, Magnetostatics, Ferrosoferric Oxide, 0104 chemical sciences, Magnetic hyperthermia, Magnetic Fields, lcsh:Biology (General), lcsh:QD1-999, Brown relaxation time, Magnetic nanoparticles, human activities
Abstract

Superparamagnetic ZnxFe3&minus, xO4 magnetic nanoparticles (0 &le, x &lt, 0.5) with spherical shapes of 16 nm average diameter and different zinc doping level have been successfully synthesized by co-precipitation method. The homogeneous zinc substitution of iron cations into the magnetite crystalline structure has led to an increase in the saturation magnetization of nanoparticles up to 120 Am2/kg for x ~ 0.3. The specific absorption rate (SAR) values increased considerably when x is varied between 0 and 0.3 and then decreased for x ~ 0.5. The SAR values are reduced upon the immobilization of the nanoparticles in a solid matrix being significantly increased by a pre-alignment step in a uniform static magnetic field before immobilization. The SAR values displayed a quadratic dependence on the alternating magnetic field amplitude (H) up to 35 kA/m. Above this value, a clear saturation effect of SAR was observed that was successfully described qualitatively and quantitatively by considering the non-linear field&rsquo, s effects and the magnetic field dependence of both Brown and Neel relaxation times. The Neel relaxation time depends more steeply on H as compared with the Brown relaxation time, and the magnetization relaxation might be dominated by the Neel mechanism, even for nanoparticles with large diameter.

Published
2020
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3. Quantitative Analysis of the Specific Absorption Rate Dependence on the Magnetic Field Strength in ZnxFe3−xO4 Nanoparticles.

Author

Kerroum, Mohamed Alae Ait, Iacovita, Cristian, Baaziz, Walid, Ihiawakrim, Dris, Rogez, Guillaume, Benaissa, Mohammed, Lucaciu, Constantin Mihai, and Ersen, Ovidiu

Subjects
*MAGNETIC flux density, *IRON oxide nanoparticles, *MAGNETIC nanoparticles, *MAGNETIC field effects, *QUANTITATIVE research, *NANOPARTICLES, *MAGNETIC fields
Abstract

Superparamagnetic ZnxFe3−xO4 magnetic nanoparticles (0 ≤ x < 0.5) with spherical shapes of 16 nm average diameter and different zinc doping level have been successfully synthesized by co-precipitation method. The homogeneous zinc substitution of iron cations into the magnetite crystalline structure has led to an increase in the saturation magnetization of nanoparticles up to 120 Am2/kg for x ~ 0.3. The specific absorption rate (SAR) values increased considerably when x is varied between 0 and 0.3 and then decreased for x ~ 0.5. The SAR values are reduced upon the immobilization of the nanoparticles in a solid matrix being significantly increased by a pre-alignment step in a uniform static magnetic field before immobilization. The SAR values displayed a quadratic dependence on the alternating magnetic field amplitude (H) up to 35 kA/m. Above this value, a clear saturation effect of SAR was observed that was successfully described qualitatively and quantitatively by considering the non-linear field's effects and the magnetic field dependence of both Brown and Neel relaxation times. The Neel relaxation time depends more steeply on H as compared with the Brown relaxation time, and the magnetization relaxation might be dominated by the Neel mechanism, even for nanoparticles with large diameter. [ABSTRACT FROM AUTHOR]

Published
2020
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