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A Mechanistic and Kinetic Study of the Formation of Metal Nanoparticles by Using Synthetic Tyrosine‐Based Oligopeptides
Author(s) -
Si Satyabrata,
Bhattacharjee Rama Ranjan,
Banerjee Arindam,
Mandal Tarun K.
Publication year - 2006
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500834
Subject(s) - tyrosine , chemistry , peptide , colloidal gold , electron paramagnetic resonance , surface plasmon resonance , nanoparticle , metal , photochemistry , redox , metal ions in aqueous solution , transmission electron microscopy , combinatorial chemistry , inorganic chemistry , organic chemistry , materials science , nanotechnology , biochemistry , nuclear magnetic resonance , physics
Synthetic oligopeptides containing redox‐active tyrosine residues have been employed to prepare gold and silver nanoparticles. In this reduction process an electron from the tyrosinate ion of the peptide is transferred to the metal ion at basic pH through the formation of a tyrosyl radical, which is eventually converted to its dityrosine form during the reaction. This reaction mechanism was confirmed from UV‐visible, fluorescence, and EPR spectroscopy and was found to be pH‐dependent. Transmission electron microscopy measurement shows that the average size and the monodispersity of gold nanoparticles increase as the number of tyrosine residues in the peptide increases. The kinetic study, based on spectrophotometric measurements of the surface plasmon resonance optical property, shows that the rate of formation of gold nanoparticles was much faster at higher pH than at lower pH and was also dependent on the number of tyrosine residues present in the peptide. The dityrosine form of the peptide was found to retain reducing properties like those of tyrosine in basic medium.