Parallel β-Sheet Assemblies at Interfaces

Polypeptide assemblies may exhibit various topologies[1-9] that are of interest for nanometer-scale surface patterning and its potential applications. The success in designing such ordered molecular architectures entails control over peptide conformations and intermolecular interactions. At the air-water interface peptides composed of alternating hydrophilic and hydrophobic amino acids tend to adopt β-sheet structures[10] yet the repetitive nature of these peptides also promotes nonspecific intermolecular aggregation. Recently, in several systems of de novo designed b-sheet peptides two-dimensional order has been demonstrated by grazing incidence X-ray diffraction[8, 9] and by scanning probe microscopy;[11] the extent of molecular registry has been associated with peptide composition and molecular chain length. Here we aim at formation of parallel β-sheet ordered assemblies at interfaces by using strands programmed to adopt distinct intermolecular electrostatic interactions.