COMPARATIVE STUDY OF SECONDARY STRUCTURES AND INTERACTIONS IN D,L-ALTERNATING PEPTIDES

The recent findings of chiral self-assembling peptides' remarkable chemical complementarity and structural compatibility make it one of the most inspired designer materials and structures in nanobiotechnology. The emerging field of designer chemistry and biology further explores biological and medical applications of these simple D,L-amino acids through producing well defined nanostructures under physiological conditions. Designer materials that are self-assembled molecules by molecule (or atom by atom) to produce novel supramolecular architectures belong to the "bottom-up" instead of the "top-down" approach and likely become an integral part of materials manufacture. This approach requires a deep understanding of individual molecular building blocks, their structures and dynamically assembly properties. The ability to control precisely the functionalization of the monomer building block is critical for control over all other levels of assembly. Chemical functionality and patterning coded in a peptide's amino acid sequence lead to control over conformation. Chemistry and conformation together control self-assembly and nanostructure. All of these together determine a material's bulk mechanical properties. Therefore, careful design of a peptide sequence should, through this bottom-up approach, allow one to control the macroscopic properties of a material. The approach presented here uses multidomain peptides that are designed to have forces favouring the assembly (hydrophobic packing, hydrogen bonding and steric effect), balanced by forces working against assembly (electrostatic repulsion). With proper balancing of these forces it is possible to control the assembly of the peptides into nanofibers. Here we highlight the design principals at the molecular level, the molecular and fine material structures, interactions of the peptides, the dynamic self-assembly behaviours, but also how we can further improve their designs.