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Electron Transfer in Peptides: On the Formation of Silver Nanoparticles
Author(s) -
Kracht Sonja,
Messerer Matthias,
Lang Matthieu,
Eckhardt Sonja,
Lauz Miriam,
Grobéty Bernard,
Fromm Katharina M.,
Giese Bernd
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201410618
Subject(s) - chemistry , electron transfer , peptide , silver nanoparticle , nanoparticle , metal , metal ions in aqueous solution , ostwald ripening , ion , histidine , amino acid , photochemistry , crystallography , nanotechnology , organic chemistry , materials science , biochemistry
Some microorganisms perform anaerobic mineral respiration by reducing metal ions to metal nanoparticles, using peptide aggregates as medium for electron transfer (ET). Such a reaction type is investigated here with model peptides and silver as the metal. Surprisingly, Ag + ions bound by peptides with histidine as the Ag + ‐binding amino acid and tyrosine as photoinducible electron donor cannot be reduced to Ag nanoparticles (AgNPs) under ET conditions because the peptide prevents the aggregation of Ag atoms to form AgNPs. Only in the presence of chloride ions, which generate AgCl microcrystals in the peptide matrix, does the synthesis of AgNPs occur. The reaction starts with the formation of 100 nm Ag@AgCl/peptide nanocomposites which are cleaved into 15 nm AgNPs. This defined transformation from large nanoparticles into small ones is in contrast to the usually observed Ostwald ripening processes and can be followed in detail by studying time‐resolved UV/Vis spectra which exhibit an isosbestic point.