Meyra Ariel G, Zarragoicoechea Guillermo J, Kuz Victor A
IFLYSIB, 59 789, La Plata, Argentina.
Phys Chem Chem Phys. 2016 May 14;18(18):12768-73. doi: 10.1039/c5cp07795h. Epub 2016 Apr 21.
In light of the coarse-grained Monte Carlo numerical simulation method, the magnetosome chain stability of magnetotactic bacteria is analysed and discussed. This discrete chain of magnetic nanoparticles, encapsulated in a lipid membrane and flanked by filaments, orients bacteria in the geomagnetic field as a compass needle. Each magnetosome is a magnetite or greigite nanocrystal encapsulated in a soft lipid shell. This structure is modelled by a hard core with a magnetic dipole embedded and a cloud of electric dipoles which are able to move and rotate over the magnetic spherical core. In the present paper, some of the many possibilities of the model by varying the control parameters of the system are explored. Magnetic particles arrange in long linear clusters when the coating is removed. However, linear but twisted chains of magnetic particles emerge when there are electric dipoles in the coating shell. A unique linear and straight chain is not observed in any 3D numerical simulation; this result is in agreement with a real living system of bacteria in a geomagnetic field when proteins that form the filament are absent. Finally, the stability and magnetization of a magnetosome chain of 30 beads in one dimension set up are discussed resembling a real chain. The results suggest that a magnetosome chain not only orients bacteria but also should be considered as a potential storage of elastic energy.
基于粗粒化蒙特卡罗数值模拟方法，对趋磁细菌的磁小体链稳定性进行了分析和讨论。这种由磁性纳米颗粒组成的离散链，包裹在脂质膜中，两侧有细丝，在地磁场中像指南针一样使细菌定向。每个磁小体是包裹在柔软脂质壳中的磁铁矿或硫复铁矿纳米晶体。这种结构通过嵌入磁偶极子的硬核以及能够在磁性球形核上移动和旋转的电偶极子云来建模。在本文中，通过改变系统的控制参数，探索了该模型的多种可能性。去除涂层时，磁性颗粒排列成长的线性簇。然而，当涂层壳中有电偶极子时，会出现线性但扭曲的磁性颗粒链。在任何三维数值模拟中都未观察到独特的线性直链；当形成细丝的蛋白质不存在时，这一结果与地磁场中细菌的真实生存系统一致。最后，讨论了一维设置中30个珠子的磁小体链的稳定性和磁化强度，类似于真实的链。结果表明，磁小体链不仅能使细菌定向，还应被视为弹性能量的潜在储存。
