Determination of dominating relaxation mechanisms from temperature-dependent Magnetic Particle Spectroscopy measurements

Draack, Sebastian; Viereck, Thilo; Nording, Felix; Janssen, Klaas Julian; Schilling, Meinhard; Ludwig, Frank

doi:10.1016/j.jmmm.2018.11.023

Cited by 32 publications

(23 citation statements)

References 8 publications

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“…Brownian dominated relaxation leads to a magnetization amplitude decrease with decreasing temperature. 24 We observed a magnetization amplitude increase and conclude that relaxation is Néel dominated. 15,24 The nanoparticles follow an alternating magnetic eld by rotation of their atomic magnetic moments (Néel-relaxation).…”

Section: Magnetic Characterization Of Non-agglomerating Spionsmentioning

confidence: 57%

“…24 We observed a magnetization amplitude increase and conclude that relaxation is Néel dominated. 15,24 The nanoparticles follow an alternating magnetic eld by rotation of their atomic magnetic moments (Néel-relaxation). 20,24 Our SPIONs are sufficiently small (TEM micrographs are provided in ESI Fig.…”

Section: Magnetic Characterization Of Non-agglomerating Spionsmentioning

confidence: 57%

“…15,24 The nanoparticles follow an alternating magnetic eld by rotation of their atomic magnetic moments (Néel-relaxation). 20,24 Our SPIONs are sufficiently small (TEM micrographs are provided in ESI Fig. S1 †) to exhibit this mechanism.…”

Section: Magnetic Characterization Of Non-agglomerating Spionsmentioning

confidence: 99%

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Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration

et al. 2021

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Section: Magnetic Characterization Of Non-agglomerating Spionsmentioning

confidence: 57%

Section: Magnetic Characterization Of Non-agglomerating Spionsmentioning

confidence: 57%

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Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration

et al. 2021

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“…Besides mere magnetic analysis, it is advantageous to use additional detectors for the determination of structural information to obtain a comprehensive picture of the synthesized MNP and to derive detailed recommendations for MNP synthesis control. For example, additional structural information can help to determine which relaxation processes dominate the magnetic signal at a given excitation (Néel, Brown) and which MPI application fields (quantitative imaging, viscosity mapping) can be derived from it [ 19 , 33 , 34 ]. A suitable detector array could contain, e.g., small-angle X-ray scattering (crystallite size), DLS (hydrodynamic size), multiangle light scattering (core/cluster size), and/or UV-Vis (concentration).…”

Section: Resultsmentioning

confidence: 99%

Novel Benchtop Magnetic Particle Spectrometer for Process Monitoring of Magnetic Nanoparticle Synthesis

et al. 2020

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Magnetic nanoparticles combine unique magnetic properties that can be used in a variety of biomedical applications for therapy and diagnostics. These applications place high demands on the magnetic properties of nanoparticles. Thus, research, development, and quality assurance of magnetic nanoparticles requires powerful analytical methods that are capable of detecting relevant structural and, above all, magnetic parameters. By directly coupling nanoparticle synthesis with magnetic detectors, relevant nanoparticle properties can be obtained and evaluated, and adjustments can be made to the manufacturing process in real time. This work presents a sensitive and fast magnetic detector for online characterization of magnetic nanoparticles during their continuous micromixer synthesis. The detector is based on the measurement of the nonlinear dynamic magnetic response of magnetic nanoparticles exposed to an oscillating excitation at a frequency of 25 kHz, a technique also known as magnetic particle spectroscopy. Our results underline the excellent suitability of the developed magnetic online detection for coupling with magnetic nanoparticle synthesis based on the micromixer approach. The proven practicability and reliability of the detector for process monitoring forms the basis for further application fields, e.g., as a monitoring tool for chromatographic separation processes.

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“…The static magnetic field B = 0.47 T (the main magnetic field of LF-NMR instrument MiniPQ001-20-15 mm), temperature T = 308.17 K (the temperature of the sample chamber of the LF-NMR instrument MiniPQ001-20-15 mm). In much of the literature, the saturation magnetization Msat of SHP series magnetic nanoparticles was measured and involved, but the values measured (or assumed) are different, but the difference is not significant [35,55,56,57,58]. From Equation (5), it can be seen that magnetic moment m is proportional to the cube power of the particle size d, but is only proportional to the first power of saturation magnetization Msat.…”

Section: Resultsmentioning

confidence: 99%

Characterization and Relaxation Properties of a Series of Monodispersed Magnetic Nanoparticles

Zhang

Cheng

Liu

2019

Sensors

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Magnetic iron oxide nanoparticles are relatively advanced nanomaterials, and are widely used in biology, physics and medicine, especially as contrast agents for magnetic resonance imaging. Characterization of the properties of magnetic nanoparticles plays an important role in the application of magnetic particles. As a contrast agent, the relaxation rate directly affects image enhancement. We characterized a series of monodispersed magnetic nanoparticles using different methods and measured their relaxation rates using a 0.47 T low-field Nuclear Magnetic Resonance instrument. Generally speaking, the properties of magnetic nanoparticles are closely related to their particle sizes; however, neither longitudinal relaxation rate r 1 nor transverse relaxation rate r 2 changes monotonously with the particle size d . Therefore, size can affect the magnetism of magnetic nanoparticles, but it is not the only factor. Then, we defined the relaxation rates r i ′ (i = 1 or 2) using the induced magnetization of magnetic nanoparticles, and found that the correlation relationship between r 1 ′ relaxation rate and r 1 relaxation rate is slightly worse, with a correlation coefficient of R 2 = 0.8939, while the correlation relationship between r 2 ′ relaxation rate and r 2 relaxation rate is very obvious, with a correlation coefficient of R 2 = 0.9983. The main reason is that r 2 relaxation rate is related to the magnetic field inhomogeneity, produced by magnetic nanoparticles; however r 1 relaxation rate is mainly a result of the direct interaction of hydrogen nucleus in water molecules and the metal ions in magnetic nanoparticles to shorten the T 1 relaxation time, so it is not directly related to magnetic field inhomogeneity.

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Determination of dominating relaxation mechanisms from temperature-dependent Magnetic Particle Spectroscopy measurements

Cited by 32 publications

References 8 publications

Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration

Reversible magnetism switching of iron oxide nanoparticle dispersions by controlled agglomeration

Novel Benchtop Magnetic Particle Spectrometer for Process Monitoring of Magnetic Nanoparticle Synthesis

Characterization and Relaxation Properties of a Series of Monodispersed Magnetic Nanoparticles

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