Serial Silver Clusters Biomineralized by One Peptide

The artificial peptide with amino acid sequence CCYRGRKKRRQRRR was used to biomineralize serial Ag clusters. Under different alkaline conditions, dusters with red and blue emission were biomineralized by the peptide, respectively. The matrix-assisted laser desorption/ionization time-of-flight mass spectra implied that the red-emitting duster sample was composed of Ag-28, while the blue-emitting cluster sample was composed of Ag-5, Ag-6, and Ag-7. The UV-visible absorption and infrared spectra revealed that the peptide phenol moiety reduced Ag ions and that formed Ag dusters were captured by peptide thiol moieties. The phenol reduction potential was controlled by the alkalinity and played an important role in determining the Ag cluster size. Circular dithroism observations suggested that the alkalinity tuned the peptide secondary structure, which may also affect the Ag cluster size.