Variation of superparamagnetic properties with iron loading in mammalian ferritin

Frankel, Richard B.; Papaefthymiou, Georgia C.; Watt, Gerald D.

doi:10.1007/bf02395857

Cited by 33 publications

(26 citation statements)

References 42 publications

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“…The fraction of the total Fe in a spherical nanoparticle that resides on the surface is quite large due to the high surface to volume ratio (

n_{s} / n_{Fe} = 4 n_{Fe}^{- 1 / 3}

[88]), ranging from 0.50 to 0.24 for particles containing 500 to 4500 Fe. A non-spherical particle has an even larger fraction of metal ions on the surface.…”

Section: Discussionmentioning

confidence: 99%

The sedimentation properties of ferritins. New insights and analysis of methods of nanoparticle preparation

May

Grady

Laue

et al. 2010

Biochimica et Biophysica Acta (BBA) - General Subjects

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Background-Ferritin exhibits complex behavior in the ultracentrifuge due to variability in iron core size among molecules. A comprehensive study was undertaken to develop procedures for obtaining more uniform cores and assessing their homogeneity.Methods-Analytical ultracentrifugation was used to measure the mineral core size distributions obtained by adding iron under high-and low-flux conditions to horse spleen (apoHoSF) and human H-chain (apoHuHF) apoferritins.Results-More uniform core sizes are obtained with the homopolymer human H-chain ferritin than with the heteropolymer horse spleen HoSF protein in which subpopulations of HoSF molecules with varying iron content are observed. A binomial probability distribution of H-and Lsubunits among protein shells qualitatively accounts for the observed subpopulations. The addition of Fe 2+ to apoHuHF produces iron core particle size diameters from 3.8 ± 0.3 to 6.2 ± 0.3 nm. Diameters from 3.4 ± 0.6 to 6.5 ± 0.6 nm are obtained with natural HoSF after sucrose gradient fractionation. The change in the sedimentation coefficient as iron accumulates in ferritin suggests that the protein shell contracts ~10% to a more compact structure, a finding consistent with published electron micrographs. The physicochemical parameters for apoHoSF (15%/85% H/L subunits) are M = 484,120 g/mol, ν̄ = 0.735mL/g, s 20,w = 17.0 S and D 20,W = 3.21 × 10 −7 cm 2 /s; and for apoHuHF M = 506,266 g/mol, ν̄ = 0.724 mL/g, s 20,w = 18.3 S and D 20,w = 3.18 × 10 −7 cm 2 /s.Significance-The methods presented here should prove useful in the synthesis of size controlled nanoparticles of other minerals.

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“…The fraction of the total Fe in a spherical nanoparticle that resides on the surface is quite large due to the high surface to volume ratio (

n_{s} / n_{Fe} = 4 n_{Fe}^{- 1 / 3}

[88]), ranging from 0.50 to 0.24 for particles containing 500 to 4500 Fe. A non-spherical particle has an even larger fraction of metal ions on the surface.…”

Section: Discussionmentioning

confidence: 99%

The sedimentation properties of ferritins. New insights and analysis of methods of nanoparticle preparation

May

Grady

Laue

et al. 2010

Biochimica et Biophysica Acta (BBA) - General Subjects

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“…The obtained blocking temperatures can be compared to values reported for horse-spleen ferritin using other detection techniques; susceptibility measurements (characteristic measurement time τ m ∼ 10 −3 -10 2 s) yield blocking temperatures in the range 5-20 K [3,5,24,33], Mößbauer spectroscopy (τ m ∼ 10 −8 s) 30-50 K [5,22,23], and electron spin resonance spectroscopy (τ m ∼ 10 −10 s) ∼ 100 K [6]. Our findings using NV magnetometry are thus consistent with previously reported results.…”

Section: Techniquementioning

confidence: 91%

“…Over this temperature range, magnetic fluctuations of ferritin cores exhibit a rich variety of dynamic phenomena like superparamagnetism [22], superantiferromagnetism [4], and macroscopic quantum tunneling [3].The Fe atoms in the biomineral core are stored in form of a hydrous ferric oxide-phosphate mineral similar in structure to ferrihydrate [23]. At lower temperatures the Fe 3+ spins are antiferromagnetically coupled with a Neél temperature estimated to be between 240 K [23] and 500 K [4].…”

mentioning

confidence: 99%

Tracking Temperature-Dependent Relaxation Times of Ferritin Nanomagnets with a Wideband Quantum Spectrometer

et al. 2014

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We demonstrate the tracking of the spin dynamics of ensemble and individual magnetic ferritin proteins from cryogenic up to room temperature using the nitrogen-vacancy color center in diamond as magnetic sensor. We employ different detection protocols to probe the influence of the ferritin nanomagnets on the longitudinal and transverse relaxation of the nitrogen-vacancy center, which enables magnetic sensing over a wide frequency range from Hz to GHz. The temperature dependence of the observed spectral features can be well understood by the thermally induced magnetization reversals of the ferritin and enables the determination of the anisotropy barrier of single ferritin molecules. The study of magnetic fluctuations -time-dependent deviations of a magnetic system from equilibrium -is of high intrinsic interest and provides a powerful tool to gain insight into magnetic coupling mechanisms [1, 2]. Experimentally, however, access to fluctuations is frequently challenging, owing to two reasons: Firstly, fluctuations can extend over an excessively large range of frequencies. Secondly, many relevant magnetic systems are small entities with dimensions in the nanometer range, such as single molecules, clusters, or magnetic domains. Hence, the study of magnetic fluctuations requires a measurement technique featuring simultaneously nanoscale resolution and a wide frequency bandwidth.Widely used methods to study ensembles of magnetic nanosystems are SQUID magnetometry [3,4], Mößbauer spectroscopy [5], electron spin resonance [6], neutron scattering [7], or X-ray magnetic circular dichroism [8]. Furthermore, individual magnetic nano-objects have been investigated by scanning probe microscopy [9, 10], micro-SQUIDs [11,12] or scanning X-ray microscopy [13]. In general these techniques have a limited detection bandwidth, such that the experimental observation of magnetic fluctuations in a wide frequency range relies on stitched measurements combining complementary techniques in different frequency domains.Here we show that the Nitrogen-Vacancy (NV) center in diamond employed as a magnetic field sensor [14,15] simultaneously provides access to both nanoscale objects and a frequency bandwidth spanning ten orders of magnitude. We use the unique properties of the NV to monitor thermal magnetization reversals of single biological nano-magnets from cryogenic to room temperature where these fluctuations accelerate from the sub-Hz to the GHz range.We study ferritin protein complexes adsorbed onto a diamond surface (Fig. 1a). Each of these proteins en- closes a cluster of up to 4500 Fe atoms wich net magnetic moment exhibits strong thermally activated fluctuations. We detect the magnetic stray field of these clusters with NV defect centers embedded 5-10 nm below the diamond surface. This center enables the precise determination of the local magnetic field via the Zeeman shift of its spin sublevels, which can be measured by optically detected magnetic resonance (ODMR) techniques. Due to its atomic size, an individual NV center can be pl...

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“…More recent data suggest as few as 1100 iron atoms in ferritin . Iron load in ferritin is dependent of the H 2 O 2 detoxification reaction and can be at low, intermediate, and high iron level …”

Section: Iron Homeostasismentioning

confidence: 99%

Genetically encoded iron‐associated proteins as MRI reporters for molecular and cellular imaging

Naumova

Velde

2017

WIREs Nanomed Nanobiotechnol

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All cell imaging applications rely on some form of specific cell labeling to achieve visualization of cells contributing to disease or cell therapy. The purpose of this review article is to summarize the published data on genetically encoded iron-based imaging reporters. The article overviews regulation of iron homeostasis as well as genetically encoded iron-associated molecular probes and their applications for noninvasive magnetic resonance imaging (MRI) of transplanted cells. Longitudinal repetitive MRI of therapeutic cells is extremely important for providing key functional endpoints and insight into mechanisms of action. Future directions in molecular imaging and techniques for improving sensitivity, specificity and safety of in vivo reporter gene imaging are discussed. WIREs Nanomed Nanobiotechnol 2018, 10:e1482. doi: 10.1002/wnan.1482 This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

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Variation of superparamagnetic properties with iron loading in mammalian ferritin

Cited by 33 publications

References 42 publications

The sedimentation properties of ferritins. New insights and analysis of methods of nanoparticle preparation

The sedimentation properties of ferritins. New insights and analysis of methods of nanoparticle preparation

Tracking Temperature-Dependent Relaxation Times of Ferritin Nanomagnets with a Wideband Quantum Spectrometer

Genetically encoded iron‐associated proteins as MRI reporters for molecular and cellular imaging

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