Dynamics of Molecular Self‐Assembly of Short Peptides at Liquid–Solid Interfaces – Effect of Charged Amino Acid Point Mutations

Abstract

Self‐organizing solid‐binding peptides on atomically flat solid surfaces offer a unique bio/nano hybrid platform, useful for understanding the basic nature of biology/solid coupling and their practical applications. The surface behavior of peptides is determined by their molecular folding, which is influenced by various factors and is challenging to study. Here, the effect of charged amino acids is studied on the self‐assembly behavior of a directed evolution selected graphite‐binding dodecapeptide on graphite surface. Two mutations, M6 and M8, are designed to introduce negatively and positively charged moieties, respectively, at the anchoring domain of the wild‐type (WT) peptide, affecting both binding and assembly. The questions addressed here are whether mutant peptides exhibit molecular crystal formation and demonstrate molecular recognition on the solid surface based on the specific mutations. Frequency‐modulated atomic force microscopy is used for observations of the surface processes dynamically in water at molecular resolution over several hours at the ambient. The results indicate that while the mutants display distinct folding and surface behavior, each homogeneously nucleates and forms 2D self‐organized patterns, akin to the WT peptide. However, their growth dynamics, domain formation, and crystalline lattice structures differ significantly. The results represent a significant step toward the rational design of bio/solid interfaces, potent facilitators of a variety of future implementations.

Structural Ordering of Interfacially Assembled Silk Fibroin-Like Peptides via Robust Intermolecular Hydrogen-Bonding Networks

“…Via a bottom-up technique, molecular self-assembly involving proteins, , peptides, , DNA, and synthetic molecules , has provided a valid method to create ordered molecular arrays on substrates. Specifically, using genetically engineered peptides for inorganics ,− including solid-binding peptides , has provided a vital clue for designing synthetic peptide sequences that lead to peptide structural ordering on solids. ,,, For example, tyrosine (Y) is important for binding and inducing ordered peptide nanostructures on 2D nanomaterials. ,, Our designed short peptides with Y(GA) n =3–5 Y sequences inspired by fibroin proteins, at extremely low peptide concentrations (<100 nM), have exhibited good water-/voltage-resisting stabilities and partial structural ordering on solids due to the formation of strong intermolecular hydrogen-bonding networks, providing potential applications for biosensing. However, at such low peptide concentrations, peptides typically undergo a long self-assembly process to reach a saturated long-range structural ordering, which slows their technological efficiency as solid-state nanodevices.…”

“…22,23,26,27 For example, tyrosine (Y) is important for binding and inducing ordered peptide nanostructures on 2D nanomaterials. 12,27,28 Our designed short peptides with Y(GA) n=3−5 Y sequences inspired by fibroin proteins, at extremely low peptide concentrations (<100 nM), have exhibited good water-/voltage-resisting stabilities and partial structural ordering on solids due to the formation of strong intermolecular hydrogen-bonding networks, 12 providing potential applications for biosensing. However, at such low peptide concentrations, peptides typically undergo a long selfassembly process to reach a saturated long-range structural ordering, which slows their technological efficiency as solid- We utilized three fibroin-like peptide sequences, termed NH 2 −Y(GA) n=3−5 Y−COOH, each containing two tyrosine (Y) residues at both the N-and C-terminals with different repeating lengths of GA motifs between the two Y residues (Figure 1A).…”