Molecular design and morphology of peptide nanotubes: towards the novel drug delivery materials

Peptide nanotubes (PNTs) are an artificial protein, being formed by the self-assembly of peptide nanorings (PNRs) consisting of alternate sequences of d- and l-amino acid residues (d,l-peptide). Because they have hollow cores and internal cavities, they are expected to be the novel drug delivery system in the future. Here, in order to give the guiding principle of the molecular design, possible molecular conformations of the peptide nanorings and nanotubes were theoretically investigated and the electronic structures were also studied by ab initio calculations. The syntheses and atomic force microscopy were further performed and the morphology of the peptide nanotubes was investigated experimentally.