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Surface‐enhanced Raman measurements and DFT calculations for l ‐tryptophan of varying pH in silver sol
Author(s) -
Bhattacharya Susmita,
Vyas Nidhi,
Ojha Animesh K.,
Dasgupta Swagata,
Roy Anushree
Publication year - 2012
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.3083
Subject(s) - chemistry , raman spectroscopy , tryptophan , colloid , surface charge , residue (chemistry) , metal , molecule , density functional theory , analytical chemistry (journal) , resonance (particle physics) , inorganic chemistry , computational chemistry , chromatography , amino acid , organic chemistry , biochemistry , physics , optics , particle physics
The interaction of l ‐tryptophan (Trp) with silver colloids was investigated at between pH values of 6.11 and 10.6 of the sol. The measurements of surface‐enhanced Raman bands of Trp in the colloidal solution indicate the evolution of interaction between the metal particles and the molecules with increasing pH values for the sol. The experimental observations were explained using the estimated atomic charge distribution in the zwitterionic and anionic forms of the residue, obtained by density functional theory calculations. The variation in the ratio of the spectral intensities of the Fermi resonance bands with the pH reflects the effect of the colloidal environment on Trp. The results obtained can be used as a marker for describing the nature of the interaction of silver colloids with the specific terminus of the residue, at varying pH environments. Copyright © 2012 John Wiley & Sons, Ltd.