Critical single domain grain sizes in chains of interacting greigite particles: Implications for magnetosome crystals
Critical single domain grain sizes in chains of interacting greigite particles: Implications for magnetosome crystals
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DOI：
10.1002/2013gc004973
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发表时间：
2013-12
期刊：
影响因子：
3.7
通讯作者：
A. Muxworthy;W. Williams;A. Roberts;M. Winklhofer;Liao Chang;M. Pósfai
中科院分区：
文献类型：
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作者：
A. Muxworthy;W. Williams;A. Roberts;M. Winklhofer;Liao Chang;M. Pósfai
趋磁细菌含有磁性相互作用的晶体链（磁小体），有助于导航（趋磁）。为了提高趋磁效率，磁小体晶体（可以由磁铁矿或灰长岩组成）应该是磁稳定的单畴（SD）颗粒。较大的颗粒细分为非均匀多畴（MD）磁性结构，产生较弱的磁信号，而较小的SD颗粒由于热波动而变得磁性不稳定，并表现出超顺磁性（SP）行为。在这项研究中，我们利用最近确定的格雷格石基本参数，确定了相同格雷格石晶粒链的稳定SD范围作为晶粒伸长率和颗粒间分离的函数。相互作用显著增加了稳定的SD范围。例如，对于立方形状的灰长岩晶粒，稳定的SD阈值尺寸从孤立晶粒的107 nm增加到排列成链的接触晶粒的204 nm。灰长岩的临界SD粒度较大意味着，与磁铁矿磁小体相比，灰长岩磁小体可以产生更大的磁性信号，而不需要晶粒间的相互作用。
Magnetotactic bacteria contain chains of magnetically interacting crystals (magnetosomes), which aid navigation (magnetotaxis). To improve the efficiency of magnetotaxis, magnetosome crystals (which can consist of magnetite or greigite) should be magnetically stable single domain (SD) particles. Larger particles subdivide into nonuniform multidomain (MD) magnetic structures that produce weaker magnetic signals, while small SD particles become magnetically unstable due to thermal fluctuations and exhibit superparamagnetic (SP) behavior. In this study, we determined the stable SD range as a function of grain elongation and interparticle separation for chains of identical greigite grains using fundamental parameters recently determined for greigite. Interactions significantly increase the stable SD range. For example, for cube‐shaped greigite grains the upper stable SD threshold size is increased from 107 nm for isolated grains to 204 nm for touching grains arranged in chains. The larger critical SD grain size for greigite means that, compared to magnetite magnetosomes, greigite magnetosomes can produce larger magnetic signals without the need for intergrain interactions.