Estimating the contribution of Brownian and Néel relaxation in a magnetic fluid through dynamic magnetic susceptibility measurements

Maldonado-Camargo, Lorena; Torres‐Díaz, Isaac; Chiu‐Lam, Andreina; Garcia-Hernandez, M.; Rinaldi, Carlos

doi:10.1016/j.jmmm.2016.03.087

Cited by 35 publications

(30 citation statements)

References 27 publications

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“…Maldonado-Camargo et al derived simple equations to estimate the fractions of the two particle types, on the condition that both Brownian and Néel relaxation times were well separated 23 . However, often the synthesis of MNP suspensions leads to a combination of magnetic and hydrodynamic particle sizes that results in relaxation by both mechanisms with an overlap in the corresponding χ" peak positions.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, measurements of AC magnetic susceptibility were exploited as a particle-specific probe, demonstrating the sensitivity to small changes in the hydrodynamic size of commercial MNPs (showing largely Brownian relaxation behaviour) due to the addition of a thin layer of RGD tripeptide. Expanding on previous characterization studies of mixed MNP suspensions 23,24 , we then monitored the progression of PEI coating and agglomeration of synthesized MNPs exhibiting both Brownian and Néel relaxation properties, where optimisation of these parameters is important for nanomagnetic transfection applications. ACS results were compared to simulations using a computational model of polydisperse nanoparticle clusters in order to determine the size distribution of both particles and clusters, and how these responded to different coating treatments.…”

Section: Introductionmentioning

confidence: 99%

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Alternating current (AC) susceptibility as a particle-focused probe of coating and clustering behaviour in magnetic nanoparticle suspensions

Narayanasamy

Cruz‐Acuña

Everett

et al. 2018

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alternating current (AC) susceptibility as a particle-focused probe of coating and clustering behaviour in magnetic nanoparticle suspensions

Narayanasamy

Cruz‐Acuña

Everett

et al. 2018

Journal of Colloid and Interface Science

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“…Deb. susc., (4) Reduced Frequency effect that emerges beyond the mean-field regime is the broadening of the peak in the imaginary part. This can be explained in term of chain formation: the chain length distribution broadens the spectrum of intrinsic relaxations in comparison to the system of non-clustered particles.…”

Section: Resultsmentioning

confidence: 99%

“…susc., (7) real Debye susc., (3) imag. Debye susc., (4) Reduced Frequency the non-ideality of the system: the low-frequency behaviour of the real part; the low-frequency growth of the imaginary part; and the peak frequency of the imaginary part.…”

Section: Comparision Between Theory and Computer Simulationsmentioning

confidence: 99%

“…Magnetic AC susceptometry is a widely used technique for analysing and characterising the dynamic magnetic response in ferrofluids [1][2][3][4]. The dynamic response of magnetic-nanoparticle suspensions is fundamentally important for medical applications in general [5], and in particular for magnetic hyperthermia, usually applied alone or in combination with other treatments to eliminate tumours [6].…”

Section: Introductionmentioning

confidence: 99%

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The influence of interparticle correlations and self-assembly on the dynamic initial magnetic susceptibility spectra of ferrofluids

Иванов

Kantorovich

Elfimova

et al. 2017

Journal of Magnetism and Magnetic Materials

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Using computer simulations and a mean-field theoretical approach, we study how the growth in dipolar interparticle correlations manifests itself in the frequency-dependent initial magnetic susceptibility of a ferrofluid. Our recently developed theory gives the correct single-particle Debye-theory results in the lowconcentration, non-interacting regime; and it yields the exact leading-order contributions from interparticle correlations. The susceptibility spectra are analysed in terms of the low-frequency behaviours of the real and imaginary parts, and the position of the peak in the imaginary part. By comparing the theoretical predictions to the results from Brownian dynamics simulations, it is possible to identify the conditions where correlations are important, but where self-assembly has not developed. We also provide a qualitative explanation for the behaviour of spectra beyond the mean-field limit. of a randomly chosen magnetic nanoparticle 1.

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Characterizing Physical Properties of Superparamagnetic Nanoparticles in Liquid Phase Using Brownian Relaxation

Schliep

Zhang

et al. 2017

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Superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively used as bioimaging contrast agents, heating sources for tumor therapy, and carriers for controlled drug delivery and release to target organs and tissues. These applications require elaborate tuning of the physical and magnetic properties of the SPIONs. The authors present here a search-coil-based method to characterize these properties. The nonlinear magnetic response of SPIONs to alternating current magnetic fields induces harmonic signals that contain information of these nanoparticles. By analyzing the phase lag and harmonic ratios in the SPIONs, the authors can predict the saturation magnetization, the average hydrodynamic size, the dominating relaxation processes of SPIONs, and the distinction between single- and multicore particles. The numerical simulations reveal that the harmonic ratios are inversely proportional to saturation magnetizations and core diameters of SPIONs, and that the phase lag is dependent on the hydrodynamic volumes of SPIONs, which corroborate the experimental results. Herein, the authors stress the feasibility of using search coils as a method to characterize physical and magnetic properties of SPIONs, which may be applied as building blocks in nanoparticle characterization devices.

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Estimating the contribution of Brownian and Néel relaxation in a magnetic fluid through dynamic magnetic susceptibility measurements

Cited by 35 publications

References 27 publications

Alternating current (AC) susceptibility as a particle-focused probe of coating and clustering behaviour in magnetic nanoparticle suspensions

Alternating current (AC) susceptibility as a particle-focused probe of coating and clustering behaviour in magnetic nanoparticle suspensions

The influence of interparticle correlations and self-assembly on the dynamic initial magnetic susceptibility spectra of ferrofluids

Characterizing Physical Properties of Superparamagnetic Nanoparticles in Liquid Phase Using Brownian Relaxation

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