Multifunctional Layered Magnetite Composites

在天然的有机-无机复合材料如珍珠层中，硬而脆的无机晶体通过软而韧性的有机材料连接在一起。由于两个组件之间的界面处的复杂的分层结构和良好控制的耦合，这些生物结构联合收割机刚度和韧性。另一个例子是石鳖牙齿，它通过嵌入多糖-蛋白质凝胶基质中的磁铁矿纳米颗粒的混合设计而具有极强的耐磨性。受这3种材料设计理念的启发，我们的目标是开发仿生复合结构，其基于天然珍珠层的不溶性基质作为支架，其填充有明胶凝胶作为天然丝水凝胶的模拟物。在该基质中，将合成具有和不具有成核剂肽的控制的磁铁矿纳米颗粒，所述成核剂肽来源于对在趋磁细菌中负责磁铁矿合成的蛋白质的研究，以利用在这些生物体中对磁铁矿成核的遗传控制。以高矿物质含量和在磁场中进行合成为目标，磁铁矿纳米颗粒应共对准，导致磁偶极子的耦合，这取决于作为趋磁细菌中磁铁矿纳米颗粒链的三维模拟物的粒度。同时，珍珠质样结构与石鳖牙齿的结构模拟相结合，可以导致抗断裂以及耐磨材料，由于磁偶极子的耦合而具有有趣的磁性能。通过调节明胶凝胶的聚合物浓度网络结构和磁铁矿含量来控制复合材料的力学性能。我们希望通过结构设计开发一种材料，该材料结合了三种不同生物矿物的最佳特性：珍珠层的断裂韧性，石鳖牙齿的耐磨性和趋磁细菌中共排列的磁铁矿纳米颗粒的磁性。这些材料的结构和性能应通过中子和X射线散射以及其他方法表征，结构材料设计将由计算机建模支持。

In natural organic-inorganic composites such as nacre, stiff and hard but brittle inorganic crystals are joined together by soft and ductile organic materials. Due to a sophisticated hierarchical structuring and a well controlled coupling at the interface between the two components, these biological structures combine both stiffness and toughness. Another example are chiton teeth which are extremely wear resistant through a hybrid design of magnetite nanoparticles embedded in a polysaccharide-protein gel matrix. Inspired by these 3 materials design concepts, we aim to develop biomimetic composite structures that are based on the insoluble matrix of natural nacre as scaffold which is filled with a gelatin gel as mimic for the natural silk hydrogel. In this matrix, magnetite nanoparticles will be synthesized with and without the control of nucleator peptides derived from studies of proteins responsible for magnetite synthesis in magnetotactic bacteria to take advantage of the genetic control over the magnetite nucleation in these organisms. With the goal of a high mineral content and performing the synthesis in a magnetic field, the magnetite nanoparticles shall be co-aligned leading to coupling of the magnetic dipoles depending on the particle size as a three dimensional mimic of the magnetite nanoparticle chains in magnetotactic bacteria. Simultaneously, the nacre-like structure combined with the structural mimic of chiton teeth could lead to fracture resistant as well as wear resistant materials coupled with interesting magnetic properties due to the coupling of the magnetic dipoles. Via the polymer concentration adjustable network structure of the gelatine gel and the magnetite content, we aim to control the mechanical properties of the composite material. We hope to develop a material which combines the best of the properties of three different biominerals by structural design: The fracture toughness of nacre, the wear resistance of chiton teeth and the magnetic properties of co-aligned magnetite nanoparticles in magnetotactic bacteria. The structure and propertes of these materials shall be characterized by Neutron and X-ray scattering as well as other methods and the structural materials design will be supported by computer modelling.