ARTICLE This journal isOligopeptide β-sheets comprising fluorenyl methoxy carbonyl (Fmoc) group on its Nterminus and five amino acid residues of cysteine, lysine and valine displays redispersive properties of agglomerated metal nanoparticles (MNPs, M = Au, Cu, Pt and Pd). The ligandfree MNPs prepared by laser ablation technique in liquid keep high dispersion state due to the inherent surface charges delivered by anionic species present in solution but may agglomerate after the preparation which depends on concentration or salinity. We show how the agglomerated MNPs can be returned to the dispersive state by adding the Fmocoligopeptide β-sheets in methanol, which is characterized by photoabsorption spectroscopy and transmission electron microscopy. Systematic studies varying the concentration, the amino acid sequences and secondary structures of a series of the oligopeptides clarify that the β-sheet structure is essential for the redispersion of the MNPs, where metal-binding thiol groups are integrated on one side and positively charged amino groups are located on the other side of the β-sheet. A possible mechanism for the redispersion may be that the agglomerated MNPs are subsequently enwrapped by the flexible β-sheets and gradually separated due to the reconstruction of peptide β-sheets under the assembly/disassembly equilibrium.

β‐Sheet formation from fluorenylmethoxycarbonyl (Fmoc)‐substituted polar oligopeptides was demonstrated, where acidic and basic side chains are located separately on either side of the β‐sheet surfaces. For yielding such charge‐separated β‐sheets, self‐assembly of 18 pentapeptides was studied, all of which contain glutamic acid (E), lysine (K), and valine (V). Fmoc‐pentapeptides containing one E and one K all formed fibrillar nanostructures consisting of stacked β‐sheets. On the other hand, Fmoc‐pentapeptides containing two E and two K formed β‐sheet fibrils only when V was located at the center and separated two EK pairs. Photoluminescence studies of these peptides in a glycine buffer containing thioflavin T revealed a clear relationship between the amino acid sequence and secondary structure, where the location of neutral V plays a pivotal role for the β‐sheet formation. The β‐sheet formation propensity was further supported by computer simulation studies with the TANGO algorithm.

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