Two-dimensional self-assembly of amphiphilic peptides; adsorption-induced secondary structural transition on hydrophilic substrate

• Regulated architectures were spontaneously constructed by the adsorption of amphiphilic peptides.
• 2D behavior of the adsorbed peptides depended on the charge combination.
• The substrate surface turned to water repellant in the opposite charge combination dominated by electrostatic interaction.
• Nanofiber array was spontaneously fabricated in the same charge combination dominated by hydrophobic interaction.

Adsorption of sequential amphiphilic peptides on solid substrates triggered the spontaneous construction of nanoscaled architecture. An amphiphilic peptide designed with a cationic amino acid as a hydrophilic residue turned an anionic mica substrate into a water-repellent surface, simply by adsorbing it on the substrate surface. In contrast, an amphiphilic peptide designed with an anionic amino-acid residue formed a precisely controlled fiber array comprising a β-sheet fiber monolayer at the anionic substrate/water interface. This phenomenon was based on the secondary structural transition from random-coil to β-sheet, which occurred specifically when amphiphilic peptide adsorbed on the substrate surface. Such surface-specific nonorder/order transition was implemented by exploiting the strength of adsorption between the peptide and the substrate. A strategic design exploiting weak bonding such as hydrophobic interactions is essential for constructing precisely controlled nano-architectures in two dimensions.

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