Coassembling Peptide-Based Biomaterials:  Effects of Pairing Equal and Unequal Chain Length Oligopeptides

Abstract

We have previously developed shear-responsive hydrogels assembled from mutually attractive but self-repulsive oligopeptide modules. To explore the mechanism of material assembly, we designed and synthesized a quartet of oligopeptides. The peptide quartet contains two positively charged modules 10 and 15 amino acid residues long and two negatively charged modules 10 and 15 amino acid residues long. Each positive module can pair with one negative module and hence there are four potential pairings, two of equal chain length (blunt-ended pairs) and two of unequal chain length (sticky-ended pairs). Viscoelastic properties and structural features of the hydrogels assembled from these oligo-peptide pairs were evaluated by dynamic rheometry and small-angle X-ray scattering (SAXS) techniques, respectively. It was found that the sticky ends provide no advantage in terms of mechanical properties of the hydrogels. Instead, the hydrogel assembled from the 10:10 peptide pair forms the strongest gel. These results are consistent with a cross-β structural model in which β-strands are stacked against each other in a parallel fashion to form nanofibers, the axes of which are perpendicular to individual β-strands. The optimal chain length of oligopeptide modules for such nanofiber network assembly is around 10 amino acid residues.

Stimulus-responsive hydrogels: Theory, modern advances, and applications

“…The hydrogel is able to withstand repeated shear thinning and still regain up to 90% of its original pre-shear rigidity. Furthermore, adjusting the hydrophobicity of the neutral amino acid species in the peptide sequence easily controls the gel modulus [471,473]. …”

Linear dependence of the water proton transverse relaxation rate on the shear modulus of hydrogels

“…During gelation, peptides aggregate into nano-scale fibers, causing structural inhomogeneity inside the hydrogel. 13 In the presence of external magnetic field, structural inhomogeneity will result in local magnetic field inhomogeneity, because macromolecules have different diamagnetic susceptibility than bulk water 14 and such difference grows with the size of the macromolecule. 15 Hence as peptide fibers form and grow, local magnetic field inhomogeneity will grow as well.…”

Gasotransmitter delivery via self-assembling peptides: Treating diseases with natural signaling gases

“…One advantage of peptide gelators based on β-sheets is their shear-thinning ability, a property that many of the classes of peptide gelators described above share [124,175,[191][192][193]. These gels flow under shear stress such as injection through a needle and exhibit time-dependent recovery upon relaxation (self-healing) [194].…”