In situ AFM investigation of dual-mode self-assembling peptide

Abstract

Nanostructures/patterns formed by biomolecules can produce different physicochemical properties in terms of hydrophobicity, zeta-potential, color, etc., which play paramount roles in life. Peptides, as the main bio-building blocks, can form nanostructures with different functions, either in solutions or on interfaces. Previously, we synthesized a short peptide with the inspiration of an Alzheimer’s disease-related peptide: amyloid β peptide (A-β), namely GAV-9, which can epitaxially self-assemble into regular nanofilaments on liquid–solid interfaces, and it was found that both the hydrophobicity and charge state of the interfaces can significantly influence its assembling behavior. It was also reported that another A-β-containing dipeptide, FF, can self-assemble into nanostructures in solutions. Owing to the close relationship between these two short peptides, it is interesting to conjugate them into a de novo peptide with two separated structural domains and study its self-assembling behavior. To this end, herein we have synthesized the GAV-FF peptide with a sequence of NH2-VGGAVVAGVFF-CONH2 and verified its self-assembling property using the in situ liquid-phase atomic force microscopy. The results show that the GAV-FF peptide can self-assemble into nanofilaments both in solutions and on aqueous–solid interfaces, but with different morphologies. The FF domain accelerates the template-assisted self-assembling (TASA) process of the GAV domain, which in return enhances the solubility of FF in aqueous solutions and further participates in the fibrillization of FF. The current results could help deepen the understanding of the aggregation mechanism of disease-related peptides and could also shed light on the strategies to create artificial bio-functional nanostructures/patterns, which hold a significant potential for biomedical applications.