Studies on hierarchical assembly from α/β-peptide foldamers

Abstract

The biomacromolecule, including nucleic acid and protein, is programmed to select supramolecular structure for the major functions like information storage and catalyzed processes. Moreover, nature uses the minor units of protein to compose structure from the complex nano/micro structure. Peptides have attracted attention as building blocks for the design and engineering of new self-assembly systems in the nano to the mesoscale range. These building blocks can integrate diverse functional motifs as designing appropriate sequences, and their effects are often manifested through hierarchical assembly. The study of hierarchical self-assembly of microparticles with non-planar peptide 3D shapes is a challenging research. Here, we report a programmed radial assembly of anisotropic microparticles derived from a helical foldamer with a C-terminal cysteine residue. The result clearly demonstrated that surface-exposed thiols of microparticles play a crucial role in bonding to form higher-order structures in an aqueous solution. Moreover, a previously reported C3-symmetric structure was reconstructed by introducing thiol functional groups on the surfaces, and a novel methodology for the formation of a unique hierarchical structure by self-assembly utilizing the interaction between functionalized surfaces was proposed. Notably, an attempt was made to expose the surface to thiol functional groups while maintaining the existing unique structure. As a result, the surface characteristics of the structure were successfully modified by the introduced functional group. Moreover, with this functional group, it was possible to create the hierarchical structure in a radial pattern. As many other foldectures with various 3D shapes are available from different foldamer designs, there is a potential for creating more complex and functional hierarchical assemblies. In addition to the radial assembly, a microtubule-like directional assembly can be achieved with a 3D assembly programmed with facet- selective functionalities. It is expected that the proposed approach will help with the design of more complicated and diverse higher-order molecular structures in the future and will find its use in the development of a surface-exposed functional group-activated template.