Formation and characterization of asymmetrical nanoparticle-superstructures

该项目的目的是合成和表征基于三角形/六方金纳米片的不对称纳米颗粒超结构。通过添加PalPhBisCarb，即Poly(N，N-二烯丙基-N，N-dimethylammonium-alt-3，5-bis-carboxyphenylmaleamincarboxylate).)，将阴离子囊泡转化为管状网络结构所得到的网络结构用作形成金纳米小片的模板相。模板相特殊的管状网络使不对称的扁平六角/三角形血小板生长。由于聚两性阳离子的存在，即PalPhBisCarb的存在，金纳米片显示出带负电荷的表面。因此，在2-20 nm的尺寸范围内(Ag、Au、Cd、Fe3O4)对带相反电荷的阳离子纳米颗粒进行吸附成为可能。这些球形粒子是在单独的成核过程中形成的，它们的稳定性是通过在其表面覆盖一种聚阳离子，即聚乙二亚胺来实现的。由于带负电荷的纳米金小片和带正电荷的球形纳米粒子之间主要是静电相互作用，而且还可以通过DNA链或硫代基团的共轭作用，在下一步可以创建超分子结构。这一策略的优点是根据吸附的球形纳米颗粒来创建高度有序结构的可调的特殊光学和磁学性质。因此，纳米尺度上具有抗菌、磁性或光电性质的高度有序的各向异性结构成为可能。由于2-20 nm量级的球形粒子的尺寸范围可根据所使用的模板(例如聚电解质修饰的微乳液)进行调整，因此组件的性质不仅可能因所吸附的纳米粒子的种类而变化，而且还可能随其粒子大小而变化。采用不对称流动分馏(AF-FFF)、动态光散射和电泳光散射结合UV-Vis光谱等方法表征了纳米粒子的大小和电荷。对于三角形和超分子结构的形态表征，将使用高分辨率透射电子显微镜(HRTEM)。由于HRTEM研究小组Koetz(EELS，EDX元素分析，断层扫描)中最先进的设备，可以直接证明单个纳米粒子在基质表面的吸附。最后，必须指出的是，该项目正在超越目前的知识状态，因为直到现在才能在不对称组装中实现独特的单分散分布。因此，该项目为具有非凡性能的多功能纳米组装件领域的进一步活动打开了一扇门。

The aim of the project is to synthesize and characterize asymmetric nanoparticle superstructures on basis of triangular/hexagonal gold nano-platelets. Anionic vesicles are transformed into a tube-like network structure by adding PalPhBisCarb, i.e. Poly(N,N-diallyl-N,N-dimethylammonium-alt-3,5-bis-carboxyphenylmaleamincarboxylate). The resulting network structure is used as a template phase for the formation of gold-nanoplatelets. The specific tube-like network of the template phase enables the growth of asymmetric flat hexagonal/triangular platelets. Due to the presence of the polyampholyte, i.e. PalPhBisCarb, the gold nanoplatelets show a negatively charged surface. Therefore, the adsorption of oppositely charged cationic nanoparticles in a size range of 2-20 nm (Ag, Au, CdS, Fe3O4) becomes possible. These spherical particles have been formed in a separate nucleation process and their stability is achieved by covering their surface with a polycation, i.e. poly(ethylenimine). Due to predominantly electrostatic interactions between negatively charged gold nano-platelets and positively charged spherical nanoparticles, but also by a conjugation via DNA strands or mercapto groups supramolecular architectures can be created in a next step. The advantage of this strategy is to create tuneable special optical and magnetic properties of the highly ordered architectures in dependence on the adsorbed spherical nanoparticles. Therefore, highly ordered anisotropic structures on the nanometerscale with antibacterial, magnetic or opto-electronical properties becomes available. Because the size range for spherical particles in the order of 2-20 nm is tuneable in dependence on the template used, e.g. polyelectrolyte-modified microemulsions, a variation of the properties of the assemblies is not only possible by the kind of the adsorbed nanoparticle but also by their particle size. Asymmetric Flow - Field Flow Fractionation (AF-FFF), dynamic and electrophoretic light scattering measurements in combination with UV-vis spectroscopy are applied for characterizing size and charge of the particles. For a morphological characterization of the triangular and supramolecular architectures High Resolution Transmission Electron Microscopy (HRTEM) will be applied. Because of the state-of-the-art equipment in the research group Koetz (EELS, EDX elemental analysis, tomography) of HRTEM, the adsorption of single nanoparticles at the surface of the matrix is directly provable. Finally, it has to be stated here that the project is exceeding the state of present knowledge because a unique monodisperse distribution in asymmetric assemblies could not be realized until now. Therefore, the project opens a door to further activities in the field of multifunctional nano-assemblies with extraordinary properties.