Materials construction through peptide design and solution assembly
July 10-14, 2016
Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic interactions; in addition to more traditional self-assembling molecular attributes such as amphiphilicty, to define hierarchical material structure and consequent properties. These self-assembled materials range from hydrogels for biomaterials to nanostructures with defined morphology and chemistry display for inorganic materials templating. The local nano- and overall network structure, and resultant viscoelastic and cell-level biological properties, of hydrogels that are formed via beta-hairpin self-assembly will be presented. Importantly, the hydrogels do not form until individual peptide molecules intramolecularly fold into a beta-hairpin conformation. Subsequently, specific, intermolecular assembly occurs into a branched nanofibrillar network. These peptide hydrogels are potentially excellent scaffolds for tissue repair and regeneration due to inherent cytocompatibility, porous morphology, and shear-thinning but instant recovery viscoelastic properties. Slight design variations of the peptide sequence allow for tunability of the self-assembly/hydrogelation kinetics as well as the tunability of the local peptide nanostructure and hierarchical network structure. In turn, by controlling hydrogel self-assembly kinetics, one dictates the ultimate stiffness of the resultant network and the kinetics through which gelation occurs. Examples of peptide primary structure alteration and the alteration of bulk network properties will be discussed. During assembly and gelation, desired components can be encapsulated within the hydrogel network such as drug compounds and/or living cells. The system can shear thin but immediately reheal to preshear stiffness on the cessation of the shear stress. Additionally, a new system comprised of coiled coil motifs designed theoretically to assemble into two-dimensional nanostructures not observed in nature will be introduced. The molecules and nanostructures are not natural sequences and provide opportunity for arbitrary nanostructure creation with peptides.
Darrin J. Pochan, "Materials construction through peptide design and solution assembly" in "Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications", ECI Symposium Series, (2016). http://dc.engconfintl.org/cmb_gels/19