Double Assembly Composed of Lectin Association with Columnar Molecular Assembly of Cyclic Tri-β-peptide Having Sugar Units

Molecular Self-Assembly and Supramolecular Chemistry of Cyclic Peptides

This Review focuses on the establishment and development of self-assemblies governed by the supramolecular interactions between cyclic peptides. The Review first describes the type of cyclic peptides able to assemble into tubular structures to form supramolecular cyclic peptide nanotubes. A range of cyclic peptides have been identified to have such properties, including α-peptides, β-peptides, α,γ-peptides, and peptides based on δ- and ε-amino acids. The Review covers the design and functionalization of these cyclic peptides and expands to a recent advance in the design and application of these materials through their conjugation to polymer chains to generate cyclic peptide-polymer conjugates nanostructures. The Review, then, concentrates on the challenges in characterizing these systems and presents an overview of the various analytical and characterization techniques used to date. This overview concludes with a critical survey of the various applications of the nanomaterials obtained from supramolecular cyclic peptide nanotubes, with a focus on biological and medical applications, ranging from ion channels and membrane insertion to antibacterial materials, anticancer drug delivery, gene delivery, and antiviral applications.

Recent advances in controlling the internal and external properties of self-assembling cyclic peptide nanotubes and dimers

Tuning the internal and external properties of self-assembling cyclic peptide nanotubes.

Peptide nanotubes

The self-assembly of different classes of peptide, including cyclic peptides, amyloid peptides and surfactant-like peptides into nanotube structures is reviewed. The modes of self-assembly are discussed. Additionally, applications in bionanotechnology and synthetic materials science are summarized.

Synthesis and conformational analysis of cyclic homooligomers from pyranoid ε-sugar amino acids

New pyranoid ε-sugar amino acids were designed as building blocks, in which the carboxylic acid and the amine groups were placed in positions C2 and C3 with respect to the tetrahydropyran oxygen atom. By using standard solution-phase coupling procedures, cyclic homooligomers containing pyranoid ε-sugar amino acids were synthesized. Conformation analysis was performed by using NMR spectroscopic experiments, FTIR spectroscopic studies, X-ray analysis, and a theoretical conformation search. These studies reveal that the presence of a methoxy group in the position C4 of the pyran ring produces an important structural change in the cyclodipeptides. When the methoxy groups are present, the structure collapses through interresidue hydrogen bonds between the oxygen atoms of the pyran ring and the amide protons. However, when the cyclodipeptide lacks the methoxy groups, a U-shape structure is adopted, in which there is a hydrophilic concave face with four oxygen atoms and two amide protons directed toward the center of the cavity. Additionally, we found important evidence of the key role played by weak electrostatic interactions, such as the five-membered hydrogen-bonded pseudocycles (C5) between the amide protons and the ether oxygen atoms, in the conformation equilibrium of the macrocycles and in the cyclization step of the cyclic tetrapeptides.

Towards functional bionanomaterials based on self-assembling cyclic peptide nanotubes

In recent years, considerable effort has been devoted to the preparation of artificial nanotubular materials. One of the most successful approaches for the construction of noncovalently bonded nanotube entities is the self-assembly of cyclic polypeptides in stacks that are stabilized by hydrogen bonds. This tutorial review covers the history and current situation for synthetic organic nanostructures obtained from self-assembling cyclic peptides. In particular, we describe the evolution to cyclic peptides that not only allow the modification of the outer surface but also the inner cavity by paying special attention to peptide rings that contain cyclic gamma-amino acids. In this respect, we describe the synthesis, properties and application of a new class of homo- and heterodimeric supramolecular assemblies that are precursors of cyclic alpha,gamma-peptide nanotubes.

Sophistication of foldamer form and function in vitro and in vivo

Advances in the foldamer field in recent years are as diverse as the backbones of which they are composed. Applications have ranged from cellular penetration and membrane disruption to discrete molecular recognition, while efforts to control the complex geometric shape of foldamers has entered the realm of tertiary and quaternary structure. This review will provide recent examples of progress in the foldamer field, highlighting the significance of this class of compounds and the advances that have been made towards exploiting their full potential.