Configuration of the magnetosome chain: a natural magnetic nanoarchitecture

Orúe, I.; Marcano, Lourdes; Bender, Philipp; Prieto, A.; València, S.; Mawass, Mohamad‐Assaad; Gil, David; Venero, Diego Alba; Honecker, Dirk; Garcı́a-Arribas, A.; Barquı́n, L. Fernández; Muela, A.; Fdez-Gubieda, M. L.

doi:10.1039/c7nr08493e

Cited by 52 publications

(89 citation statements)

References 57 publications

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“…And third, the evolution of the SAR curves as a function of the applied field for both magnetosomes and magnetotactic bacteria follows a similar trend, being negligible below a certain threshold field (which lies around 200 Oe in this case). As we pointed out in our previous works, this is a clear hallmark of intrinsic hysteresis losses (which can be modeled by a Stoner–Wohlfarth approach) being the main mechanism of the heat production.…”

Section: Resultssupporting

confidence: 82%

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Gandia

Gandarias

Rodrigo

et al. 2019

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Magnetotactic bacteria are aquatic microorganisms that internally biomineralize chains of magnetic nanoparticles (called magnetosomes) and use them as a compass. Here it is shown that magnetotactic bacteria of the strain Magnetospirillum gryphiswaldense present high potential as magnetic hyperthermia agents for cancer treatment. Their heating efficiency or specific absorption rate is determined using both calorimetric and AC magnetometry methods at different magnetic field amplitudes and frequencies. In addition, the effect of the alignment of the bacteria in the direction of the field during the hyperthermia experiments is also investigated. The experimental results demonstrate that the biological structure of the magnetosome chain of magnetotactic bacteria is perfect to enhance the hyperthermia efficiency. Furthermore, fluorescence and electron microscopy images show that these bacteria can be internalized by human lung carcinoma cells A549, and cytotoxicity studies reveal that they do not affect the viability or growth of the cancer cells. A preliminary in vitro hyperthermia study, working on clinical conditions, reveals that cancer cell proliferation is strongly affected by the hyperthermia treatment, making these bacteria promising candidates for biomedical applications.

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Section: Resultssupporting

confidence: 82%

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Gandia

Gandarias

Rodrigo

et al. 2019

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111

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“…In this work, we exploit polarized small-angle neutron scattering (SANS) to gain information about directional correlations between the moments within clusters of 10nm iron oxide cores in the superparamagnetic regime, here at 300 K. Elastic neutron scattering has a measurement time scale on the order of a picosecond [48] and is therefore capable of capturing snapshots of the magnetic ordering within core-clusters, in which relaxations of the entire cluster occurs on longer time scales (ns regime). Furthermore, SANS provides information about magnetic correlations on the nanoscale and offers thus a unique approach to study magnetic nanoparticle systems, as also done in other studies [49][50][51][52][53][54][55]. We, however, performed a complete longitudinal neutron-spin analysis in SANS (POLARIS) [56], through which we were able to detect the purely magnetic scattering cross sections.…”

Section: Introductionmentioning

confidence: 99%

Dipolar-coupled moment correlations in clusters of magnetic nanoparticles

et al. 2018

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Here, we resolve the nature of the moment coupling between 10-nm DMSA-coated magnetic nanoparticles. The individual iron oxide cores were composed of > 95 % maghemite and agglomerated to clusters. At room temperature the ensemble behaved as a superparamagnet according to Mössbauer and magnetization measurements, however, with clear signs of dipolar interactions. Analysis of temperature-dependent AC susceptibility data in the superparamagnetic regime indicates a tendency for dipolar coupled anticorrelations of the core moments within the clusters. To resolve the directional correlations between the particle moments we performed polarized small-angle neutron scattering and determined the magnetic spin-flip cross-section of the powder in low magnetic field at 300 K. We extract the underlying magnetic correlation function of the magnetization vector field by an indirect Fourier transform of the cross-section. The correlation function suggests non-stochastic preferential alignment between neighboring moments despite thermal fluctuations, with anticorrelations clearly dominating for next-nearest moments. These tendencies are confirmed by Monte Carlo simulations of such core-clusters.

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“…Magnetosomes are arranged as highly ordered chains of singledomain magnetite (Fe3O4) or greigite (Fe3S4) crystals individually coated in a phospholipid membrane and usually attached to a protein filament that aligns them with the axis of the bacterium [2,3]. Composition not withstanding individual magnetosomes possess the key advantages of high ferrimagnetism, narrow size distribution (20-120 nm) and shape distribution [2][3][4][5][6] and biologically compatible surface chemistry [5,7]. Furthermore, their membrane contains specific transmembrane proteins that can be exploited for biotechnological applications, e.g.…”

Section: Introductionmentioning

confidence: 99%

Nanoparticle Tracking Analysis: A powerful tool for characterizing magnetosome preparations

Fernández-Castañé

Joseph

et al. 2020

Preprint

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Nanoparticle Tracking Analysis (NTA) has been employed to measure the particle concentration and size distribution of magnetosomes extracted and purified from Magnetospirillum gryphiswaldense MSR-1, and then exposed to probe ultrasonication for various times, or 1% (w/v) sodium dodecyl sulphate (SDS) for 1 h. Particle concentration increased 3.7-fold over the first 15 min of ultrasonication (from 2 × 10 8 to >7.3 × 10 8 particles mL -1 ), but fell steeply to ~3.6 × 10 8 particles mL -1 after 20 min. NTA of untreated magnetosome preparation confirmed a wide particle distribution dominated by larger species (D[1,0] = 312 nm; Dn50 = 261 nm; mode = 243 nm) with no particles in the size range of isolated single magnetosomes. After 5 min of ultrasonication the whole particle size distribution shifted to smaller size (D[1,0] = 133 nm; Dn50 = 99 nm; mode = 36 nm, corresponding to individual magnetosomes), but longer treatment times (15 and 20 min) reversed the previous transition; all characteristic numbers of the particle size distributions increased and very few small particles were detected. Side-by-side comparison of NTA and TEM sizing data revealed remarkable similarity at low ultrasonication times, with both showing single magnetosomes accounted for ~30% population after 5 min. Exposure of magnetosomes to SDS resulted in a ~3-fold increase in particle concentration to 5.8 × 10 8 particles mL -1 , narrowing of the size distribution and gross elimination of particles below 60 nm. We conclude that NTA is a rapid cost-effective technique for measuring particle number, size distribution and aggregation state of magnetosomes in solution, but requires further work to improve its resolving power.

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Configuration of the magnetosome chain: a natural magnetic nanoarchitecture

Cited by 52 publications

References 57 publications

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Dipolar-coupled moment correlations in clusters of magnetic nanoparticles

Nanoparticle Tracking Analysis: A powerful tool for characterizing magnetosome preparations

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