Self-assembly of hierarchical magnetic nano- to microstructures: biogenic and biomimetic synthesis of magnetite chains

趋磁细菌形成了细胞内的磁小体链，这些磁小体在几个层次上显示出分级有序的纳米和微结构，直到对整个细胞群体的协调排列和运动的磁性控制。细菌磁性结构是由被膜包裹的生物矿化的磁性纳米晶体生物矿化形成的，这些磁性纳米晶体又通过自组装排列成更复杂的结构。细菌磁小体的形成受到严格的生物控制，这与前所未有的材料特性有关。然而，尽管材料科学做出了相当大的努力，所产生的复杂的磁性结构还没有被传统的技术方法复制。在这个项目中，我们提出了一种仿生的方法来合成层次化的磁性纳米材料，该方法受到细菌系统的启发。在之前对分子决定因素和构建块进行了鉴定和表征之后，我们现在的目标是在体外重建从细菌中纯化的磁性纳米晶体的组装。特别是，这将涉及细菌蛋白MamK和MamJ，它们共同形成控制体内磁小体链排列的细胞骨架网络。接下来，生物成分将被部分取代，并与新的材料成分结合，如改性聚合物结构和仿生磁性纳米颗粒。最终，我们将应用生物组装的原理来设计具有新颖和定制的机械、物理化学和磁性材料特性的层次化有序的二维和三维纳米和微结构。

Magnetotactic bacteria form intracellular chains of magnetosomes, which display a hierarchically ordered nano- and microstructure over several levels, up to the magnetic control of coordinated alignment and motility of entire populations of cells. The bacterial magnetic structures are formed by biomineralization from membrane-enveloped, biomineralized magnetic nanocrystals, which in turn by self-assembly align into more complex structures. Bacterial magnetosome formation is under strict biological control, which is associated with unprecedented material properties. However, despite of considerable efforts by material sciences, the resulting complex magnetic structures have not been replicated yet by conventional technological approaches.In this project, we suggest a biomimetic approach for the synthesis of hierarchically structured magnetic nanomaterials, which is inspired by the bacterial system. After previous identification and characterization of molecular determinants and building blocks, we now aim to reconstitute in vitro the assembly of magnetic nanocrystals purified from bacteria. In particular, this will involve the bacterial proteins MamK and MamJ which are known to collectively form the cytoskeletal network controlling alignment of magnetosome chains in vivo. Next, biological constituents will be partially substituted and combined with novel material components, such as modified polymeric structures and biomimetic magnetic nanoparticles. Ultimately, we will apply the principles of biological assembly to design hierarchically ordered two- and three-dimensional nano- and microstructures with novel and tailored mechanical, physico-chemical, and magnetic material characteristics.