Effect of peptide ligand dipole moments on the redox potentials of Au38 and Au140 nanoparticles.
Phenylethanethiolate monolayer-protected Au38 and Au140 nanoclusters were modified by ligand place exchange with a series of thiolated peptides. The peptides were homooligomers based on the alpha-aminoisobutyiric acid unit. The effects of changing the peptide concentration and the peptide length in the capping monolayer were studied by differential pulse voltammetry. The results showed that the redox behavior of the nanoparticles can be affected very significantly by such modifications. For example, the first oxidation peak of Au38, a cluster displaying molecule-like behavior, could be shifted positively by as much as 0.7-0.8 V. Detectable redox shifts were noted even when one single oriented peptide was in the Au140 monolayer. These effects were attributed to the molecular dipole moments of the peptide ligands.
Holm
Allan H
AH
Department of Chemistry, University of Padova, via Marzolo 1, 35131 Padova, Italy.
Ceccato
Marcel
M
Donkers
Robert L
RL
Fabris
Laura
L
Pace
Giuseppe
G
Maran
Flavio
F
D000621:Aminoisobutyric Acids / Q000737:chemistry; D004563:Electrochemistry; D006046:Gold / Q000737:chemistry*; D008024:Ligands; D008968:Molecular Conformation; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
D000621:Aminoisobutyric Acids; D008024:Ligands; D010455:Peptides; D013438:Sulfhydryl Compounds; C100049:2-aminoisobutyric acid; D006046:Gold