Revisiting the conformational adsorption of L- and D-cysteine on Au nanoparticles by Raman spectroscopy
Por:
Rodriguez-Zamora, P., Salazar-Angeles, B., Buendia, F., Cordero-Silis, C., Fabila, J., Bazan-Diaz, L., Fernandez-Diaz, L. M., Paz-Borbon, L. O., Diaz, G., Garzon, I. L.
Publicada:
1 feb 2020
Ahead of Print:
1 dic 2019
Resumen:
Understanding the physical mechanisms of thiolated molecules adsorption
on metal surfaces has required copious research, particularly on
Au-cysteine systems due to the affinity of sulfur molecules to gold
surfaces, as well as the interesting structural modifications that this
strong interaction induces and the peculiar optical, chiroptical, and
electronic properties of Au(SR) systems. Here, we present vibrational
experimental data on the adsorption of L- and D-cysteine on small gold
nanoparticles (<2 nm) by means of Raman spectroscopy. L- and D-cysteine
molecules adopt the same strained conformation upon adsorption on
colloidal gold nanoparticles, regaining structure due to the
stabilization that the gold nanoparticle induces on the cysteine,
reflected in the recuperation of vibrational bands from their
polymorphically distinctive crystalline forms. Through the analysis of
Raman vibrational modifications after adsorption, we found experimental
evidence that confirms a stabilized cysteine conformation locating the
carboxyl group in the antiposition (P-C isomeric rotamer) for both
molecules. This result is supported by extensive density functional
theory (DFT) calculations and simulated Raman spectra, considering
zwitterionic cysteine adsorbed on a Au-34 cluster, emulating
experimental nanoparticle sizes. Our Raman spectroscopy experimental and
DFT results determine one of the oxygen atoms of the carboxyl group as a
second adsorption site after the sulfur atom, confirming that
independent of its polymorphism and enantiomerism, zwitterionic cysteine
interacts with gold nanoparticles through the thiol group and the
carboxyl group as adsorption sites.
Filiaciones:
Rodriguez-Zamora, P.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Salazar-Angeles, B.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Buendia, F.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Cordero-Silis, C.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Fabila, J.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Bazan-Diaz, L.:
Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA
Fernandez-Diaz, L. M.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Paz-Borbon, L. O.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Diaz, G.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
Garzon, I. L.:
Univ Nacl Autonoma Mexico, Inst Fis, Mexico City, DF, Mexico
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