Construction and Piezoelectric Properties of a Single-Peptide Nanotube Composed of Cyclic β-peptides with Helical Peptides on the Side Chains

Abstract

To develop nanopiezoelectronics, it is necessary to investigate the relationship between the sizes and piezoelectric properties of the material. Peptide nanotubes (PNTs) composed of cyclic β-peptides have been studied as leading candidates for nanopiezoelectric materials. The current drawback of PNTs is aggregation to form a PNT bundle structure due to strong dipole–dipole interactions between PNTs. Here, we report the construction and piezoelectric properties of single PNTs without nonspecific aggregation by side-chain modification of helical peptides. A cyclic tri-β-peptide with a helical peptide was prepared by multiple-step liquid-phase peptide synthesis and assembled into PNTs by the vapor diffusion method. These nanotubes were characterized by polarized light microscopy and Fourier transform infrared (FTIR) spectroscopy. Additionally, atomic force microscopy (AFM) topographic images showed nanotubes with a height of 4 nm, which corresponds to the diameter of a PNT on a gold-coated mica substrate, indicating that a single PNT was prepared successfully. The converted piezoelectric response of a single PNT was determined to be 1.39 ± 0.12 pm/V. This value was consistent with that of a PNT bundle, which reveals that the piezoelectricity of PNTs is induced by deformation of their cyclic skeletons and is independent of the bundled structure. This finding not only demonstrates a new molecular design strategy to construct these smallest piezoelectric biomaterials by controlling the supramolecular hierarchical structures but also provides insights into the correlation between molecular assembly morphology and size-dependent piezoelectric properties.

Self‐Assembling Peptide‐Based Functional Biomaterials

“…The side chain introduced helical peptide has a three‐dimensional structure, which can hinder the contact between PNTs, resulting in the formation of a single PNT structure. The piezoelectric experiment results show that the converted piezoelectric response of a single PNT is 1.39±0.12 pm V −1 , which achieved strong piezoelectric performance through smaller‐sized nanostructures [116] . A recent study revealed a peptide‐based co‐assembly strategy that achieves a dramatic improvement in piezoelectric performance.…”

Recent advancements in piezoelectric energy harvesting for implantable medical devices

“…The temperature impact on piezoelectric for biological applications was explored by Rotan et al (2021). For in vivo evaluation, biomaterials such as AIN-based flexible nanogenerator (Mariello et al, 2021), KNN-based lead-free heterogeneous structure PEH (Zhang et al, 2021a) and helical peptide nanotube-based NG (Kurita et al, 2021) are particularly suited and compatible.…”

Recent Advances in the Solid- and Solution-Phase Synthesis of Peptides and Proteins Using Microflow Technology

“…α-Peptides comprising proteinogenic amino acids usually suffer from poor pharmacological properties, such as low metabolic stability and cell membrane permeability. Specialty peptides, including N-methylated peptides, ,− β-peptides, ,− and cyclic peptides, ,− generally have higher metabolic stability. In particular, it is believed that cyclic N-methylated peptides have better affinity and specificity against their biological targets because of their constrained chemical structure.…”