Sequence-Encoded Supramolecular Assembly of Peptide Amphiphiles

We used all-atom molecular dynamics calculations to elucidate the origin of the twisting that occurs in self-assembled peptide amphiphile (PA) ribbons. By changing the sequence length of VE repeats that are found to form twisted ribbons, we have connected the twisting to β-sheet formation in combination with hydrogen bonds between the strands. The right-handed twisted β-sheets are found to stack along the growth direction in a left-handed manner, which leads to a left-handed twisted ribbon. Furthermore, a chirality change from left-handed to right-handed twisted ribbons can be observed by introducing GRGD, which implies that GLY and protonated ARG do not have a bias toward right-handed twisted β-sheets. We also report the molecular design of supramolecular-covalent hybrid materials by incorporating PAs with various morphologies into photoactive covalent polymers. Supramolecular fibrous morphologies were found to play a more significant role in providing mechanical reinforcement and enhanced photoactuation. MD simulations indicate that the supramolecular fiber effectively facilitates the transport of trapped water molecules by functioning as a channel and therefore enhancing the actuation of the hybrid system. These are crucial for the precise design of chiral and hybrid materials.