Nanoribbons self-assembled from short peptides demonstrate the formation of polar zippers between beta-sheets

Peptide self-assembly is a hierarchical process, often starting with the formation of a-helices, beta-sheets or beta-hairpins. However, how the secondary structures undergo further assembly to form higher-order architectures remains largely unexplored. The polar zipper originally proposed by Perutz is formed between neighboring beta-strands of poly-glutamine via their side-chain hydrogen bonding and helps to stabilize the sheet. By rational design of short amphiphilic peptides and their self-assembly, here we demonstrate the formation of polar zippers between neighboring beta-sheets rather than between beta-strands within a sheet, which in turn intermesh the beta-sheets into wide and flat ribbons. Such a super-secondary structural template based on well-defined hydrogen bonds could offer an agile route for the construction of distinctive nanostructures and nanomaterials beyond beta-sheets.