title: Self-assembled nanomaterials based on beta (β(3)) tetrapeptides.
abstract: β(3)-amino acid based polypeptides offer a unique starting material for the design of self-assembled nanostructures such as fibres and hierarchical dendritic assemblies, due to their well-defined helical geometry in which the peptide side chains align at 120° due to the 3.0-3.1 residue pitch of the helix. In a previous work we have described the head-to-tail self-assembly of N-terminal acetylated β(3)-peptides into infinite helical nanorods that was achieved by designing a bioinspired supramolecular self-assembly motif. Here we describe the effect of consecutively more polar side chains on the self-assembly characteristics of β(3)-tetrapeptides Ac-β (3)Ala-β(3)Leu-β(3)Ile-β(3)Ala (Ac-β(3)[ALIA]), Ac-β(3)Ser-β(3)Leu-β(3)Ile-β(3)Ala (Ac-β(3)[SLIA]) and Ac-β (3)Lys-β (3)Leu-β(3)Ile-β (3)Glu (Ac-β(3)[KLIE]). β(3)-tetrapeptides complete 1 1/3 turns of the helix: thus in the oligomeric form the side chain positions shift 120° with each added monomer, forming a regular periodic pattern along the nanorod. Dynamic light scattering (DLS) measurements confirmed that these peptides self-assemble even in highly polar solvents such as water and DMSO, while diffusion-ordered NMR spectroscopy revealed the presence of a substantial monomeric population. Temperature dependence of the size distribution in DLS measurements suggests a dynamic equilibrium between monomers and oligomers. Solution casting produced distinct fibrillar deposits after evaporating the solvent. In the case of the apolar Ac-β(3)[ALIA] the longitudinal helix morphology gives rise to geometrically defined (∼70°) junctions between fibres, forming a mesh that opens up possibilities for applications e.g. in tissue scaffolding. The deposits of polar Ac-β(3)[SLIA] and Ac-β(3)[KLIE] exhibit fibres in regular parallel alignment over surface areas in the order of 10 μm.
authors.affiliation: Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Bundoora, Victoria 3086, Australia.
authors.forename: Rania S
authors.initials: RS
authors.lastname: Seoudi
authors.forename: Mark G
authors.initials: MG
authors.lastname: Hinds
authors.forename: David J D
authors.initials: DJ
authors.lastname: Wilson
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Adda
authors.forename: Mark
authors.initials: M
authors.lastname: Del Borgo
authors.forename: Marie-Isabel
authors.initials: MI
authors.lastname: Aguilar
authors.forename: Patrick
authors.initials: P
authors.lastname: Perlmutter
authors.forename: Adam
authors.initials: A
authors.lastname: Mechler
mesh_terms: D000067493:Dynamic Light Scattering; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry*; D009842:Oligopeptides / Q000737:chemistry*; D012997:Solvents; D013696:Temperature
chemical_list: D009842:Oligopeptides; D012997:Solvents