(35c) Hierarchical Self-Assembly Pathways of Peptoid Helical Rods and Sheets

Rational design of hierarchical self-assembling nanomaterials is predicated on the fundamental understanding of their atomic-level assembly pathways. Here, we conduct an integrated computational and experimental investigation of the hierarchical self-assembly pathways of short amphiphilic peptoids. Peptoids are a class of highly tailorable synthetic peptidomics polymers with various applications including drugs, antimicrobials, and catalyst. Polypeptoids can be engineered to assemble into various hierarchical nanostructures including spheres, ribbons, helices, tubes, and sheets. For a particular peptoid design, we resolve some previously unknown critical stages in the peptoid assembly pathway for the formation of crystalline sheets using molecular dynamics calculations that we corroborate by experimental measurements. Our results support an assembly mechanism by which monomers first assemble into disordered cylindrical aggregates that transit into helical rods, and that multiple helices aggregate and unravel into crystalline sheets. We make predictions through simulations for the thermodynamically stable structures as a function of solvent conditions, which is validated by experimental observations. This new understanding of the hierarchical peptoid assembly pathways provides guidance for tuning self-assembly behaviors through solvent conditions and the future rational design of peptoid-based nanomaterials.

Acknowledgment

This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, as part of the Energy Frontier Research Centers program: CSSAS—The Center for the Science of Synthesis Across Scales under Award Number DE‐SC0019288.