Shaping of Nanotubules Formed by Amino Acid Amphiphiles

• Applicant: Professor Dr. Michael Gradzielski
• Co-Applicant: Professorin Dr. Dganit Danino
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2013 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 233624625

Self-assembled nanotubes are highly interesting colloidal systems due to their well-defined structural characteristics and typically simple formation by a bottom-up process. Yet, so-far, these structures have been studied only scarcely and their detailed aggregation properties are still poorly understood. Our project aims for an in-depth investigation of the formation of self-assembled nanotubes made of peptide-mimetic amphiphiles (amino acid amphiphiles, AAAs), and involves molecular design and analysis in two principal directions. For this comprehensive approach we will bring together the complementary expertise of the Technion (D. Danino) and TUB (M. Gradzielski) group in the fields of self-assembly and its characterisation. In the first direction we will establish relations between the tendency to form nanotubes, and the molecular architecture and chemical motifs of the designed AAAs. This will involve systematic variations of the amphiphile structure, where the synthetic work required will be shared between the labs. Subsequently a detailed characterization of the aggregate structure by direct imaging (microscopy), scattering, calorimetry and spectroscopy methods will be done to access features at the nm- and µm-scale. Here in particular the complementarity of direct imaging (TEM, Technion) and scattering techniques (TUB) is important for obtaining a detailed structural picture. From these results correlations between the mesoscopic structure and the molecular build-up of the AAAs will be derived. For that, as throughout the whole research project, an intense and frequent exchange of research results will be done, in order to optimise the joint research progress.In addition, state-of-the-art time-resolved cryo-TEM, SANS and SAXS experiments will be done in a complementary fashion to allow following the kinetics of the structural transitions and to determine intermediate structures. This is of key importance for the understanding of the driving forces of self-assembly and the pathways involved in nanotube formation. Such knowledge then is the essential for optimising nanotube formation in a rational way. In the second direction we will study to what extent the assembly process of our tailor-made AAAs can be controlled by the solution properties (solvent quality) or the addition of polymer surfactants as structure directing agents. This shall allow for a simple way to access tailor-made tubules with tuneable, well-controlled radii and wall thickness, but employing a given type of AAA.Based on this work we will investigate the potential of these nanotubes as templates for forming novel materials. This will be done in an exploratory way for forming Ag and titania/silica rods or tubules as interesting colloids. Thus, this project will yield a fundamental and comprehensive understanding of the molecular bottom-up approach for forming self-assembled nanotubes, and bringing them closer to applications as novel colloidal systems.

• DFG Programme: Research Grants
• International Connection: Israel