Effect of tryptophan residues on gold mineralization by a gold reducing peptide

Abstract

Increasing the number of tryptophan (Trp) in peptides led to higher gold reducing ability and the peptides could disperse the generated gold-nanoparticles.

Sequence rules for gold-binding peptides

“…The importance of this residue in AuNP synthesis is known for its ability to reduce Au 3+ ions, 25,26 wherein increasing the number of tryptophan residues in a gold biomineralization peptide leads to an increase in reducing efficiency. 27 However, the binding affinity data for the decapeptides used in this study were obtained using already formed AuNPs. This suggests that the importance of tryptophan in gold-binding peptides is due to its contribution to binding to the AuNP surface and not for its ability to reduce Au ions and inuence nucleation.…”

Spatiotemporally controlled drug delivery via photothermally driven conformational change of self-integrated plasmonic hybrid nanogels

“…The PHNs, basically composed of gold nanoparticles (GNPs) and the heat-sensitive nanogel, can be easily tuned for their physicochemical properties by changing the species of linker molecules during the synthetic process. For this purpose, we have applied 6-different biocompatible and functional linker molecules with different molecular weights; N , N ′-methylene bis(acrylamide): a common crosslinker for polymerization of NIPAM [ 39 ], tryptophan: an amino acid with reducing power for gold ions [ 67 , 68 ], sucrose and alginate: hydrophilic sugar molecules for the stabilization of GNPs [ 49 , 51 ], poly(ethylene glycol) diacrylate: a linker molecule having acryl groups for NIPAM polymerization [ 69 ], and gelatin: a water-soluble protein for the capping of GNPs [ 70 , 71 ]. Since the ligand-free GNPs were easily formed by free radicals generated from the photoinitiator [ 46 , 47 ], they could pull the hydrophilic moieties of the polymeric network via weak interactive forces [ 48 , 49 ].…”

Shape control of Au nanostructures using peptides for biotechnological applications

“…In experiments where the number of Trp residues in AuBP1 was increased, the diameters of the AuNPs decreased as the number of Trp residues in the sequences increased. 13 Thus, the reducing power of Au ions can be controlled by the number of π-electrons in the aromatic ring of the Trp residue in the peptide sequence. That is, by changing the number and type of aromatic rings in the array, the nucleation rate of Au ions can be varied, and the size of the AuNPs can be controlled.…”

“…(2) The affinity for Au ions can be easily adjusted by changing the amino acid sequence. 13 (3) Certain peptides can reduce Au ions without reducing agents, which are environmentally hazardous. Thus, the reduction process minimally burdens the environment.…”