Supramolecular self-assembly represents a powerful approach to the design of functional nanomaterials. Peptide self-assembled systems offer significant advantages including biological compatibility, ease of synthesis, low toxicity and functionalisability. However, the control over essential features such as chemical, structural and metabolic stability, the scale and relatively slow rate of self-assembly remain significant challenges. Using peptides consisting of only β3-amino acids offers the means to overcome these limitations. β3 peptides exhibit high metabolic stability. Structurally, they adopt stable, helical conformations in solution. 14-Helical β3-peptides in particular contain exactly 3 residues per complete turn of the helix (ie n = 3) and thus form cylindrical molecules with perfect longitudinal alignment of residues. This provides extraordinary opportunities for designing new materials with functionality located along these faces. Perhaps even more significant, is that the perfect pitch offers the opportunity to design a supramolecular self-assembly motif to link the monomers in a highly symmetrical manner reminiscent of one dimensional crystallization.
We hypothesized that a H-bonding motif similar to that required for 14-helical stabilization would, if propagated intermolecularly, mediate axial head-to-tail self-assembly, and ultimately promote fibre formation. This mode of fibre self-assembly contrasts with existing approaches which predominantly exploit lateral interactions, rather than axial, assembly motifs. Indeed we have now found that 14-helical, N-acetyl β3-peptides spontaneously self-assemble in a unique head-to-tail fashion to form fibres from solution. Fibre size can be controlled from the nano-to macro scale.[1] The inherent flexibility in design and ease of synthesis provide powerful new avenues for the development of novel bio- and nanomaterials via supramolecular self-assembly.
[1] Mark P. Del Borgo, Adam I. Mechler, Daouda Traore, Craig Forsyth, Jacqueline A. Wilce, Matthew C. J. Wilce, Marie-Isabel Aguilar and Patrick Perlmutter “Supramolecular Self-Assembly of N-Acetyl Capped β-Peptides Leads to Nano-to Macroscale Fibre Formation” Angew. Chem. Int. Ed.,2013, 10.1002/anie.201303175.