Lipids exhibit an extraordinary polymorphism in self-assembled mesophases, with lamellar phases as the most relevant biological representative. To mimic lipid lamellar phases with amphiphilic designer peptides, seven systematically varied short peptides were engineered. Indeed, four peptide candidates (V₄D, V₄WD, V₄WD₂, I₄WD₂) readily self-assembled into lamellae in aqueous solution. Small-angle X-ray scattering (SAXS) patterns revealed ordered lamellar structures with a repeat distance of ~ 4–5 nm. Transmission electron microscopy (TEM) images confirmed the presence of stacked sheets. Two derivatives (V₃D and V₄D₂) remained as loose aggregates dispersed in solution; one peptide (L₄WD₂) formed twisted tapes with internal lamellae and an antiparallel β-type monomer alignment. To understand the interaction of peptides with lipids, they were mixed with phosphatidylcholines. Low peptide concentrations (1.1 mM) induced the formation of a heterogeneous mixture of vesicular structures. Large multilamellar vesicles (MLV, d-spacing ~ 6.3 nm) coexisted with oligo- or unilamellar vesicles (~ 50 nm in diameter) and bicelle-like structures (~ 45 nm length, ~ 18 nm width). High peptide concentrations (11 mM) led to unilamellar vesicles (ULV, diameter ~ 260–280 nm) with a homogeneous mixing of lipids and peptides. SAXS revealed the temperature-dependent fine structure of these ULVs. At 25 ℃ the bilayer is in a fully interdigitated state (headgroup-to-headgroup distance d_HH ~ 2.9 nm), whereas at 50 ℃ this interdigitation opens up (d_HH ~ 3.6 nm). Our results highlight the versatility of self-assembled peptide superstructures. Subtle changes in the amino acid composition are key design elements in creating peptide- or lipidpeptide nanostructures with richness in morphology similar to that of naturally occurring lipids.

Hierarchical self-assembly is a fundamental principle in nature, which gives rise to astonishing supramolecular architectures that are an inspiration for the development of innovative materials in nanotechnology. Here, we present the unique structure of a cone-shaped amphiphilic designer peptide. While tracking its concentration-dependent morphologies, we observed elongated bilayered single tapes at the beginning of the assembly process, which further developed into novel double-helix-like superstructures at high concentrations. This architecture is characterized by a tight intertwisting of two individual helices, resulting in a periodic pitch size over their total lengths of several hundred nanometers. Solution X-ray scattering data revealed a marked 2-layered internal organization. All these characteristics remained unaltered for the investigated period of almost three months. In their collective morphology, the assemblies are integrated into a network with hydrogel characteristics. Such a peptide-based structure holds promise as a building block for next-generation nanostructured biomaterials.