Symmetry breaking-induced double-strand helices in H-bonded coassembly

A broad-spectrum antibacterial hydrogel based on the synergistic action of Fmoc-phenylalanine and Fmoc-lysine in a co-assembled state

Multicomponent biomolecular self-assembly is fundamental for accomplishing complex functionalities of biosystems. Self-assembling peptides, amino acids, and their conjugates serve as a versatile platform for developing biomaterials. However, the co-assembly of multiple building blocks showing synergistic interplay between individual components and producing biomaterials with emergent functional attributes is much less explored. In this study, we have formulated minimalistic co-assembled hydrogels composed of Fmoc-phenylalanine and Fmoc-lysine. The co-assembled systems display broad-spectrum antimicrobial potency, a feature absent in individual building blocks. A comprehensive biophysical analysis demonstrates the physicochemical features of the hydrogels eliciting the antibacterial response. MD simulation further reveals a unique fibrillar architecture with Fmoc-phenylalanine forming the fibril core surrounded by positively charged Fmoc-lysine surface residues, thereby enhancing the interaction with negatively charged bacterial membranes, causing membrane disruption and cell death. Thus, this study provides molecular-level insight into the emergent properties of a multicomponent system, affording an excellent paradigm for developing novel biomaterials.

Metal-ion-triggered symmetry breaking of completely achiral azobenzene amphiphiles in water

Achieving control over symmetry breaking of completely achiral components in the aqueous phase is a significant challenge in supramolecular chemistry. Herein, we demonstrate that it is possible to construct chiral nanoassemblies by introducing metal ions (Zn2+, Fe3+, Al3+, Cu2+, and Ca2+) into completely achiral azobenzene amphiphiles with key structural factors in the pure aqueous phase. It is found that the coordination interactions, π-π stacking, hydrophilic and hydrophobic interactions, hydrogen bonding, and electrostatic interactions are crucial to the metal-ion-induced symmetry breaking of completely achiral building blocks. This study may provide an intriguing model system for constructing chiral assemblies based on completely achiral molecules.

Bioinspired Amino Acid Based Materials in Bionanotechnology: From Minimalistic Building Blocks and Assembly Mechanism to Applications

Inspired by natural hierarchical self-assembly of proteins and peptides, amino acids, as the basic building units, have been shown to self-assemble to form highly ordered structures through supramolecular interactions. The fabrication of functional biomaterials comprised of extremely simple biomolecules has gained increasing interest due to the advantages of biocompatibility, easy functionalization, and structural modularity. In particular, amino acid based assemblies have shown attractive physical characteristics for various bionanotechnology applications. Herein, we propose a review paper to summarize the design strategies as well as research advances of amino acid based supramolecular assemblies as smart functional materials. We first briefly introduce bioinspired reductionist design strategies and assembly mechanism for amino acid based molecular assembly materials through noncovalent interactions in condensed states, including self-assembly, metal ion mediated coordination assembly, and coassembly. In the following part, we provide an overview of the properties and functions of amino acid based materials toward applications in nanotechnology and biomedicine. Finally, we give an overview of the remaining challenges and future perspectives on the fabrication of amino acid based supramolecular biomaterials with desired properties. We believe that this review will promote the prosperous development of innovative bioinspired functional materials formed by minimalistic building blocks.

Chiral macrocycle-induced circularly polarized luminescence of a twisted intramolecular charge transfer dye

The host-guest binding between a chiral macrocycle and an achiral dye could suppress the twisted intramolecular charge transfer (TICT) process, leading to enhanced emission and bright circularly polarized luminescence (CPL) from the originally achiral TICT-dye.