Abstract
Raman and surface enhanced Raman scattering (SERS) spectroscopies were used to study the pH effect (7 to 9) on the interaction of arginine (Arg) with colloidal Ag nanoparticles (AgNps). A new methodology was implemented in order to obtain reproducible SERS spectra in solution. The dependence of the Arg concentration on the stability of the AgNps is discussed. A pH increasing of the colloidal solution to the limits of the Arg pKa(2) value induces a preferential and stable Arg-metal interaction. potential measurements of the Arg-AgNps system at different pH conditions studied provide information about the Arg-AgNps interaction; the pH increasing favors the interaction. SERS spectra at pH 7 indicate that the molecule interacts with the Ag surface only through the guanidinium fragment. By increasing the pH to 9, the molecule adopts a new conformation on the surface; the metal-analyte interaction is verified through the guanidinium, carboxylate and the aliphatic moieties. In addition, theoretical calculations performed by using the extended Huckel method for a model of Arg interacting with an Ag surface support the observed SERS results.
- (eht),
- (sers),
- (xi),
- amino-acids,
- aromatic-hydrocarbons,
- dqcauchile
- enhanced
- extended
- huckel
- hydrochloride
- l-arginine,
- l-lysine,
- polycyclic
- potential
- protein,
- raman
- scattering
- scattering,
- spectra,
- spectroscopy,
- surface
- surface,
- temperature,
- theory
- zeta
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