1D Self-Assembly of Peptides and Lipids into Ribbons and Nanotubes

Abstract

In nature, 1D supramolecular structures are expressed on various length scales, ranging from the formation of nanotubes by lipids, steroids and their mixtures, or collagen self-organization into triple helix fibers, to templating of the chiral property onto the inorganic phase organization at the organism level as in sea shells and insect exoskeletons. Fibrillation is also associated with many human amyloid diseases, including Alzheimer, type II diabetes and multiple sclerosis, thus motivating research from various bio-related fields. Apparent advantages of 1D molecular assemblies, e.g., structural strength and mechanical rigidity, stability, and primarily structural diversity and build-in functionality also foster the application of natural building blocks and their mimics in emerging nano-biotechnology fields.Here we focus on the principles of 1D self-assembly of small chiral amphiphiles into ribbons and nanotubes. Interestingly, we find several distinct self-assembly pathways, all leading eventually to identical morphologies. Cryo-TEM plays a key role in the investigations. Specifically, with a designed peptide amphiphile cryo-TEM elucidated the complete pathway to nanotubes, passing through several ribbon intermediates, and a dynamic transition between ribbon morphologies. With lipids, cryo-TEM provided the first direct evidence to the route by which multilamellar lipid nanotubes are formed, showing sequential events during the transformation of uni- and multilamellar lipid vesicles to corresponding uni- and multilamellar nanotubes.