Mixed Brownian alignment and Néel rotations in superparamagnetic iron oxide nanoparticle suspensions driven by an ac field

Shah, Saqlain A.; Reeves, Daniel B.; Ferguson, R. Matthew; Weaver, John B.; Krishnan, Kannan M.

doi:10.1103/physrevb.92.094438

Cited by 121 publications

(81 citation statements)

References 35 publications

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“…This behavior indicates that there is a delay between the magnetization and the applied field associated with the angle between the applied field and the easy axis, which implies a difference in the anisotropy energy barrier. Similar results for superparamagnetic nanoparticles and ferromagnetic nanoparticles have been obtained previously from both numerical simulations and experiments [18][19][20] . Figure 7 shows the distribution of the number of particles for the 5±2 nm particles obtained from numerical simulations at a frequency of 100 kHz and intensity of 16 kA/m.…”

Section: A D V a N C E P U B L I C A T I O Nsupporting

confidence: 89%

Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

et al. 2018

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Magnetic particle imaging (MPI) is a novel diagnostic imaging technique based on the use of magnetic nanoparticles (MNPs). Investigating the magnetic properties of magnetic nanoparticles is important for achieving a high spatial and temporal resolution in MPI. In this study, -Fe2O3 nanoparticles (core diameter: dc = 4 nm), Fe3O4 nanoparticles (dc = 20-30 nm), and Resovist ® were immobilized in a DC magnetic field with their easy axes aligned. DC and AC magnetization curves were measured for the prepared MNPs. The measurements were performed by applying fields parallel and perpendicular to the easy axis and evaluating the magnetic properties of the MNPs for the easy and hard axes. The direction of magnetic moments under the AC magnetic field applied to the direction of the easy axis or hard axis was evaluated by using both experimental results and numeric simulation using the Landau-Lifshitz-Gilbert equation to reveal magnetic relaxation property at wide frequency range and the effect of core size distribution of oriented MNPs. The effect of anisotropy in superparamagnetic nanoparticles, the relaxation property depending on the anisotropy energy barrier, and the fast magnetization process of Néel relaxation were successfully observed.

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Section: A D V a N C E P U B L I C A T I O Nsupporting

confidence: 89%

Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

et al. 2018

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“…It is known that physicochemical properties of SPIOs and the surrounding solvent environment can influence their magnetic response to external fields 7,8 . Properties of SPIO cores such as core size and size distribution, iron oxide phase and crystallinity dictate the magnetic response and must be optimized to generate images with both high signal intensity and high resolution.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of PEG-coated iron oxide nanoparticles as blood pool tracers for preclinical magnetic particle imaging

et al. 2017

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Superparamagnetic iron oxide (SPIO) nanoparticles with optimized and well-characterized properties are critical for Magnetic Particle Imaging (MPI). MPI is a novel in vivo imaging modality that promises to integrate the speed of CT, safety of MRI and sensitivity of PET. Since SPIOs are the source of MPI signal, both the core and surface properties must be optimized to enable efficient in vivo imaging with pharmacokinetics tailored for specific imaging applications. Existing SPIOs like Resovist (ferucarbotran) provide suboptimal MPI signal, and further limit MPI's in vivo utility due to rapid systemic clearance. An SPIO agent with a long blood half-life (t1/2) would be a versatile MPI tracer with widespread applications. Here we show a long circulating polyethylene glycol (PEG)-coated SPIO tracer, LS-008, provides excellent colloidal stability and persistent intravascular MPI signal, showing potential as the first blood pool tracer optimized for MPI. We evaluated variations of the PEG coating and found that colloidal stability of tracers improved with increasing PEG molecular weight (keeping PEG loading constant). Blood circulation in mice, evaluated using Magnetic Particle Spectrometry (MPS), showed that t1/2 of SPIO tracers varied with both PEG molecular weight and loading. LS-008, coated with 20 kDa PEG at 18.8% loading capacity, provided the most promising long-term colloidal stability with a t1/2 of about 105 minutes in mice. In vivo MPI imaging with LS-008 in a 7 T/m/μ0 3D x-space MPI mouse scanner revealed a prolonged intravascular signal (3-5 hours) post-injection. Our results show the optimized magnetic properties a nd long systemic retention of LS-008 make it a promising blood pool MPI tracer, with potential to enable MPI imaging in cardio - and cerebrovascular disease models, and solid tumor quantification and imaging via enhanced permeation and retention.

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“…χ está retrasada con respecto al campo de excitación, esta componente determina la capacidad de absorber energía y es la única que contribuye al aumento de la energia interna ∆U de la partícula [46], [47], [48] y se puede escribir de la siguiente forma:…”

Section: Ingeniería Y Cienciaunclassified

Una guía para el estudio de nanopartículas magnéticas de óxidos de hierro conaplicaciones biomédicas. Parte I

Coral

Mera

2017

ing.cienc.

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ResumenEl siguiente artículo corresponde a una revisión teórica y experimental sobre las las principales propiedades físicas de un sistema de nanopartículas magnéticas con aplicaciones en el tratamiento del cáncer por hipertermia magnética. Así, se divide el mismo en dos partes: en la primera parte, correspondiente a esta entrega, se realiza una revisión teórica detallada sobre las principales propiedades de las nanopartículas, y las leyes físicas que las rigen, tales como magnetización, interacciones entre partículas y su ordenamiento en suspensiones coloidales. En una segunda entrega, se tratarán temas como la síntesis de nanopartículas, técnicas y modelos de caracterización física y medidas experimentales de disipación de calor bajo campos de radiofrecuencia, y su correlación con los modelos mostrados en este artículo. Se presenta este trabajo como una guía ya que ofrece una serie de pautas importantes para tener en cuenta al momento de realizar una investigación en nanopartículas magnéticas. Palabras clave: Disipación de calor; hipertermia magnética; nanopartí-culas magnéticas; óxidos de hierro; propiedades.

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Mixed Brownian alignment and Néel rotations in superparamagnetic iron oxide nanoparticle suspensions driven by an ac field

Cited by 121 publications

References 35 publications

Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

Dynamic Hysteresis Measurement of Magnetic Nanoparticles with Aligned Easy Axes

Evaluation of PEG-coated iron oxide nanoparticles as blood pool tracers for preclinical magnetic particle imaging

Una guía para el estudio de nanopartículas magnéticas de óxidos de hierro conaplicaciones biomédicas. Parte I

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