An Offset Patterned Cross‐β Structure in Assemblies of C3‐Symmetric Peptide Amphiphiles

Abstract

AbstractDeveloping peptide‐based materials with controlled morphology is a critical theme of soft matter research. Herein, we report the formation of a novel, patterned cross‐β structure formed by self‐assembled C3‐symmetric peptide amphiphiles based on diphenylalanine and benzene‐1,3,5‐tricarboxamide (BTA). The cross‐β motif is an abundant structural element in amyloid fibrils and aggregates of fibril‐forming peptides, including diphenylalanine. The incorporation of topological constraints on one edge of the diphenylalanine fragment limits the number of β‐strands in β‐sheets and leads to the creation of an unconventional offset‐patterned cross‐β structure consisting of short 3×2 parallel β‐sheets stabilized by phenylalanine zippers. In the reported assembly, two patterned cross‐β structures bind parallel arrays of BTA stacks in a superstructure within a single‐molecule‐thick nanoribbon. In addition to a threefold network of hydrogen bonds in the BTA stack, each molecule becomes simultaneously bound by hydrogen bonds from three β‐sheets and four phenylalanine zippers. The diffuse layer of alkyl chains with terminal polar groups prevents the nanoribbons from merging and stabilizes cross‐β‐structure in water. Our results provide a simple approach to the incorporation of novel patterned cross‐β motifs into supramolecular superstructures and shed light on the general mechanism of β‐sheet formation in C3‐symmetric peptide amphiphiles.