Controlled assembly of covalent-supramolecular peptide ‘bundlemer’ nanostructures

Computationally designed peptides that are 29 amino acids in length could self-assemble into stable antiparallel, homotetrameric coiled coils in the water. These coiled-coil peptides, or ‘bundlemers’, have great potential to serve as fundamental building blocks to construct well-defined nanostructures. By tuning bundle surface-exposed functional groups and peptide termini, various natural and non-natural physical and covalent inter-bundle interactions can be introduced for nanostructure formation. The building blocks can be ‘click’ conjugated together to form a 1D physical-covalent hybrid supramolecular polymer. Herein, we focus on novel ladder-like covalent-supramolecular hybrid polymers by clicking together end-functionalized bundlemers with complimentary side-functionalized bundlemers. Constituent peptides with different designed net charges under different self-assembly and conjugation conditions have been studied. Additional designs discussed include bundlemers used to construct branched fibers and 2D peptide networks. Peptide design will be discussed as well as transmission electron microscopy, atomic force microscopy, and small-angle x-ray scattering results characterizing the ladder and 2-D nanostructures.