Constructing supramolecular peptide lattices through rational design and mixing of charged coiled-coil peptide ‘bundlemers’*

Self-assembling peptides can form supramolecular coil-coiled motifs that can serve as a basic building block for hierarchical assembly. Computationally designed, non-natural coiled-coil bundles, also known as ‘bundlemers’, offer precise control over surface charge and functional groups at the nanometer level. This control enables specific electrostatic interactions and, consequently, the potential for well-ordered interparticle solution behavior. Herein, we introduce a novel category of single-charged coiled-coil bundlemers where only one type of amino acid charge is present on the coiled-coil structures. Through a controlled mixing of these opposite charge peptide bundlemer particles in solution, highly ordered, two dimensional lattice nanostructures were observed under transmission electron microscopy. By strategically controlling the overall charge and the specific position of charged amino acids on the respective, oppositely charged bundlemer surfaces, the solution assembly behavior of oppositely charged bundlemer mixtures could be changed from amorphous aggregates to well-defined, two-dimensional lattices. Small-angle x-ray scattering helped elucidate the diverse assembly morphologies in solution depending on the different charge designs of the inherent bundlemers. Further investigations have demonstrated that self-assembly behavior can be well controlled by fine-tuning the assembling pathway and conditions.