Ultrafine Au and Ag Nanoparticles Synthesized from Self‐Assembled Peptide Fibers and Their Excellent Catalytic Activity

Abstract

The self-assembly of an amphiphilic peptide molecule to form nanofibers facilitated by Ag(+) ions was investigated. Ultrafine AgNPs (NPs=nanoparticles) with an average size of 1.67 nm were synthesized in situ along the fibers due to the weak reducibility of the -SH group on the peptide molecule. By adding NaBH4 to the peptide solution, ultrafine AgNPs and AuNPs were synthesized with an average size of 1.35 and 1.18 nm, respectively. The AuNPs, AgNPs, and AgNPs/nanofibers all exhibited excellent catalytic activity toward the reduction of 4-nitrophenol, with turnover frequency (TOF) values of 720, 188, and 96 h(-1) , respectively. Three dyes were selected for catalytic degradation by the prepared nanoparticles and the nanoparticles showed selective catalysis activity toward the different dyes. It was a surprising discovery that the ultrafine AuNPs in this work had an extremely high catalytic activity toward methylene blue, with a reaction rate constant of 0.21 s(-1) and a TOF value of 1899 h(-1) .

Self-assembled nanoreactors based on peptides and proteins

“…Amyloid-like catalytic nanofiber self-assembly starts with assembly of short peptide sequences into β-sheets via hydrophobic interactions [17], where individual β-strands can be lined up in an anti-parallel fashion [18,19], but are most commonly parallel aligned [19][20][21][22][23][24]. Hydrogen-bonding as well as hydrophobic and electrostatic interactions drive further assembly into stable peptide nanofibers of approximately 10 nm width and with lengths of several hundred nanometers In the bottom panel origins of catalytic activity are detailed: (a) one polar amino acid is substituted with a catalytic residue to give rise to nanofibers with catalytic activity; (b) multiple similar peptides with different catalytic residues co-assemble into fibers with multiple catalytic activities; (c) multiple polar residues are substituted with catalytic amino acids within a single amphiphilic peptide sequence to give rise to nanofibers containing multiple catalysts; (d) a catalytic sequence is fused to an amphiphilic peptide to generate a nanofiber that displays the catalytic sequence on its surface.…”

“…[17]. Generally, the amyloid peptide sequence is sufficient to induce self-assembly into fibers, although some peptides require the presence of metal ions in order to self-assemble [24].…”

“…Xu and coworkers [24] designed an Ac-FFACD-OH 5-mer peptide sequence that relied on Ag + ions for self-assembly into nanofibers. As was the case in the systems described above, the presence of the metal ion was vital to catalytic activity of this system, although the mechanism was completely different.…”

The Investigation of a Multi‐Functional Peptide as Gelator, Dyes Separation Agent and Metal Ions Adsorbent

“…In this peptide molecule, FF have been reported to form gels easily, C can be used to prepare noble metal nanoparticles due to the existence of thiol group, and D is an acidic amino acid, which endows the peptide acidity and electronegativity. The Au nanoparticles (AuNPs) and Ag nanoparticles (AgNPs) have been prepared in our last work . Ac‐FFACD‐OH can be dissolved in DMSO, then diluted into PBS buffer solution.…”

“…The Au nanoparticles (AuNPs) and Ag nanoparticles (AgNPs) have been prepared in our last work. [38] Ac-FFACD-OH can be dissolved in DMSO, then diluted into PBS buffer solution. Gels are formed in a wide range of pH values from 1.0 to 6.0.…”