Role of Hydrophobicity on Self-Assembly by Peptide Amphiphiles via Molecular Dynamics Simulations

Using a novel coarse-grained model, large-scale molecular dynamics simulations were performed to examine self-assembly of 800 peptide amphiphiles (sequence palmitoyl-V(3)A(3)E(3)). Under suitable physiological conditions, these molecules readily assemble into nanofibers leading to hydrogel construction as observed in experiments. Our simulations capture this spontaneous self-assembly process, including formation of secondary structure, to identify morphological transitions of distinctive nanostructures. As the hydrophobic interaction is increased, progression from open networks of secondary structures toward closed cylindrical nanostructures containing either beta-sheets or random coils are observed. Moreover, temperature effects are also determined to play an important role in regulating formation of secondary structures within those nanostructures. These understandings of the molecular interactions involved and the role of environmental factors on hydrogel formation provide useful insight for development of innovative smart biomaterials for biomedical applications.