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Magnetite Crystal Orientation in Magnetosome Chains.

Körnig A, Winklhofer M, Baumgartner J, Gonzalez TP, Fratzl P, Faivre D - Adv Funct Mater (2014)

Bottom Line: One-dimensional magnetic nanostructures have magnetic properties superior to non-organized materials due to strong uniaxial shape anisotropy.The obtained pole figure patterns reveal a [111] fiber texture along the chain direction for magnetospirilla strains MSR-1 and AMB-1, whereas a [100] fiber texture is measured for Desulfovibrio magneticus strain RS-1.The pronounced fiber textures can be explained either by a strain-specific biological control on crystal orientation at the chain level or by physical alignment effects due to intra-chain magnetic interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces Science Park Golm, 14424, Potsdam, Germany.

ABSTRACT

One-dimensional magnetic nanostructures have magnetic properties superior to non-organized materials due to strong uniaxial shape anisotropy. Magnetosome chains in magnetotactic bacteria represent a biological paradigm of such magnet, where magnetite crystals synthesized in organelles called magnetosomes are arranged into linear chains. Two-dimensional synchrotron X-ray diffraction (XRD) is applied to cells of magnetotactic bacteria that are pre-aligned with a magnetic field to determine the crystallographic orientation of magnetosomes relative to the chain axis. The obtained pole figure patterns reveal a [111] fiber texture along the chain direction for magnetospirilla strains MSR-1 and AMB-1, whereas a [100] fiber texture is measured for Desulfovibrio magneticus strain RS-1. The [100] axis appears energetically unfavorable because it represents a magnetic hard axis in magnetite, but can be turned into an effective easy axis by particle elongation along [100] for aspect ratios higher than 1.25, consistent with aspect ratios in RS-1 magnetosomes determined earlier. The pronounced fiber textures can be explained either by a strain-specific biological control on crystal orientation at the chain level or by physical alignment effects due to intra-chain magnetic interactions. In this case, biological control of the axis of elongation would be sufficient to influence the crystallographic texture of the magnetosome chain.

No MeSH data available.


Related in: MedlinePlus

TEM images of wildtype (A) and ΔmamJ mutant (B) cells of MSR-1 dried in the presence of a magnetic field, scale bars represent 1 μm.
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fig01: TEM images of wildtype (A) and ΔmamJ mutant (B) cells of MSR-1 dried in the presence of a magnetic field, scale bars represent 1 μm.

Mentions: The magnetotactic bacteria were deposited either on a transmission electron microscoy (TEM) grid for imaging or on a Kapton foil for XRD analysis and dried in the presence of a magnetic field of 100 mT. TEM images (Figure1) show that the cell bodies are oriented such that their magnetosome chains are aligned with the externally applied magnetic field, resulting in samples in which all magnetosome chains were close to parallel to each other.


Magnetite Crystal Orientation in Magnetosome Chains.

Körnig A, Winklhofer M, Baumgartner J, Gonzalez TP, Fratzl P, Faivre D - Adv Funct Mater (2014)

TEM images of wildtype (A) and ΔmamJ mutant (B) cells of MSR-1 dried in the presence of a magnetic field, scale bars represent 1 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4384753&req=5

fig01: TEM images of wildtype (A) and ΔmamJ mutant (B) cells of MSR-1 dried in the presence of a magnetic field, scale bars represent 1 μm.
Mentions: The magnetotactic bacteria were deposited either on a transmission electron microscoy (TEM) grid for imaging or on a Kapton foil for XRD analysis and dried in the presence of a magnetic field of 100 mT. TEM images (Figure1) show that the cell bodies are oriented such that their magnetosome chains are aligned with the externally applied magnetic field, resulting in samples in which all magnetosome chains were close to parallel to each other.

Bottom Line: One-dimensional magnetic nanostructures have magnetic properties superior to non-organized materials due to strong uniaxial shape anisotropy.The obtained pole figure patterns reveal a [111] fiber texture along the chain direction for magnetospirilla strains MSR-1 and AMB-1, whereas a [100] fiber texture is measured for Desulfovibrio magneticus strain RS-1.The pronounced fiber textures can be explained either by a strain-specific biological control on crystal orientation at the chain level or by physical alignment effects due to intra-chain magnetic interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces Science Park Golm, 14424, Potsdam, Germany.

ABSTRACT

One-dimensional magnetic nanostructures have magnetic properties superior to non-organized materials due to strong uniaxial shape anisotropy. Magnetosome chains in magnetotactic bacteria represent a biological paradigm of such magnet, where magnetite crystals synthesized in organelles called magnetosomes are arranged into linear chains. Two-dimensional synchrotron X-ray diffraction (XRD) is applied to cells of magnetotactic bacteria that are pre-aligned with a magnetic field to determine the crystallographic orientation of magnetosomes relative to the chain axis. The obtained pole figure patterns reveal a [111] fiber texture along the chain direction for magnetospirilla strains MSR-1 and AMB-1, whereas a [100] fiber texture is measured for Desulfovibrio magneticus strain RS-1. The [100] axis appears energetically unfavorable because it represents a magnetic hard axis in magnetite, but can be turned into an effective easy axis by particle elongation along [100] for aspect ratios higher than 1.25, consistent with aspect ratios in RS-1 magnetosomes determined earlier. The pronounced fiber textures can be explained either by a strain-specific biological control on crystal orientation at the chain level or by physical alignment effects due to intra-chain magnetic interactions. In this case, biological control of the axis of elongation would be sufficient to influence the crystallographic texture of the magnetosome chain.

No MeSH data available.


Related in: MedlinePlus