Using the Bending Beam Model to Estimate the Elasticity of Diphenylalanine Nanotubes

The core recognition motif of the amyloidogenic β-amyloid polypeptide, diphenylalanine peptide, has previously been shown to self-assemble into discrete, well-ordered, stiff nanotubes under mild conditions. The nanotubes keep the same morphology from room temperature up to 100 °C. In the presented study, we applied the bending beam model to atomic force microscopy images of diphenylalanine nanotubes suspended across cavities and obtained the Young's modulus 27 ± 4 GPa and the shear modulus 0.21 ± 0.03 GPa. We also showed that the elasticity of these nanotubes is stable within the same temperature range and at relative humidity from 0% to 70%. This study furthers our understanding of the structure and properties of these nanotubes, which are important for their potential applications in biotechnology.