CNT Binding Peptides Selected by the Phage Display Method

Abstract

Using the M13 phage display method, 236 amino acid sequences (peptide aptamers) that could specifically adsorb to CNTs were selected. These peptide aptamers had abundant hydrophobic amino acids and evenly dispersed charged amino acids. The hydrophobic amino acids were postulated to contribute to CNT adsorption, while the charged amino acids contribute to their aqueous solubility. The frequency of proline amino acids, which causes the amino acid main chain bending, was slightly higher than in nature, suggesting that some conformational constraint might be required. Four peptide aptamers with a high frequency of occurrence in the selected sequences were further studied. Hydrophobicity scores were periodic along the amino acid sequence. 3D structure predictions by PEP-FOLD3 indicated that these aptamers would take a helical structure with hydrophobic amino acid residues on one side, suggesting that the aptamers bind hydrophobically to the CNT. The adsorption of these four aptamers to the carbon electrode was confirmed by electrochemical impedance spectroscopy, which demonstrated the effectiveness of the phage display method. At the same time, it was shown that even for selected peptides, the adsorption performance varied, and verification was needed.

Enhanced Adsorption of Cage-Shaped Proteins on Carbon Surfaces by Carbon Nanotube (CNT)-Binding Peptide Aptamers

“…One of the mutants was Dps modified with carbon nanohorn binding peptide (DYFSSPYYEQLF, CNHB-Dps). The rest were Dps modified with two kinds of CNT-binding peptide aptamers, Y1 (FKQDAWEAVDIR) and Y2 (SYTHLLHRSLPG), which we recently selected using the M13 phage display method [25]. Y1Nt; Y1 was genetically added to the N-terminus of the subunit via a linker (SGGG).…”

“…Y2Ct; Y2 was added to the C-terminus of the subunit via a linker. Y1 and Y2 were predicted to adopt an alpha-helical conformation by 3D structural prediction (Figure S3) [25]. The dispersed charged amino acids ensured hydrophilicity, while adsorption to the carbon surface was thought to be based on hydrophobic interactions.…”

“…The key to the nanostructured placement of proteins with nanoparticle cores at designated device locations is to control the selective adsorption of proteins by peptide aptamers genetically immobilized on the outer surface. Therefore, studies have been conducted on the adsorption of peptide aptamers on inorganic materials such as metallic materials [20][21][22], inorganic compounds such as silicon dioxide (SiO2) [23], and carbon nanomaterials [24,25]. By controlling adsorption, the proteins work as self-assembled nano-building blocks, combining with semiconductor processes to create new composite structures with high magnetoconductivity, electro-optical properties, and physicochemical properties [7,[16][17][18].…”

“…We have recently obtained CNT-binding peptide aptamers consisting of 12 amino acids using a phage display method [25]. The obtained peptide aptamers showed significantly higher adsorption capacity on carbon surfaces compared to ordinary peptides.…”