Abstract
Diphenylalanine (FF) is a peptide that can form different nanostructures; this makes it particularly attractive for both biological and technological applications. However, any application using this type of nanostructures requires controlling their size and shape. Information is provided about the various structures formed through the peptide FF self-assembly in different salt solutions (NaCl, CaCl2, and AlCl3), concentrations (50 mM, 100 mM, and 200 mM), and pH (3 to 10). Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the nanotubes. Results show that FF nanotube formation through self-assembly is a delicate balance between electrostatic, hydrogen bonding, and hydrophobic interactions; any imbalance in these can impede nanotube formation. Our results demonstrate that salts, such as NaCl and CaCl2, along with the studied concentrations promote the formation of very long nanotube agglomerates. This would be due to a combined screening effect and the fact that cations are structure-forming and promote hydrophobic interactions; therefore, nanotube agglomeration occurs and also benefits electrostatic interactions, hydrogen bonds, and longer nanotubes. The presence of AlCl3 produces an imbalance in the abovementioned interactions because of excess Cl-, a structure-breaking anion that impedes the nanostructure formation.
Highlights
Peptide self-assembly to form well-ordered hierarchical structures has drawn much attention because of its centrality in biological processes such as amyloid fibril formation associated with neurodegenerative diseases and in the design of novel nanostructures with potential applications ranging from biotechnology to nanotechnology [1–13]
The simplest peptide building block is diphenylalanine (FF), the core recognition motif of Alzheimer’s β-amyloid polypeptide, which has proven very interesting because it can self-assemble into different nanostructures depending on experimental conditions [1, 2, 15, 20–30]
Self-assembly of FF is driven by a greater affinity of nanotubes among themselves than with water
Summary
Peptide self-assembly to form well-ordered hierarchical structures has drawn much attention because of its centrality in biological processes such as amyloid fibril formation associated with neurodegenerative diseases and in the design of novel nanostructures with potential applications ranging from biotechnology to nanotechnology [1–13]. The great variety of structures formed is directly related to the forces and their synergies, manifested during the self-assembly process [14–19]. The simplest peptide building block is diphenylalanine (FF), the core recognition motif of Alzheimer’s β-amyloid polypeptide, which has proven very interesting because it can self-assemble into different nanostructures depending on experimental conditions [1, 2, 15, 20–30]. Concentrated salt solutions affect the structure and nature of proteins, including their solubility, denaturation, and dissociation [32–36]. Remarkable is that almost always the FF is dissolved in organic solvent, for example, 1,1,1,3,3,3-hexafluoro-2-propanol, and some of them were
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call