Structure and properties of citrate overlayers adsorbed at the aqueous Au(111) interface.

Wright,LB, Rodger,PM and Walsh,TR 2014, Structure and properties of citrate overlayers adsorbed at the aqueous Au(111) interface., Langmuir, vol. 30, no. 50, pp. 15171-15180, doi: 10.1021/la503690t.

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Title Structure and properties of citrate overlayers adsorbed at the aqueous Au(111) interface.
Author(s) Wright,LB
Walsh,TRORCID iD for Walsh,TR
Journal name Langmuir
Volume number 30
Issue number 50
Start page 15171
End page 15180
Publisher American Chemical Society
Place of publication United States
Publication date 2014-12-23
ISSN 1520-5827
Keyword(s) Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry, Physical
Materials Science, Multidisciplinary
Materials Science
Summary One of the most common means of gold nanoparticle (AuNP) biofunctionalization involves the manipulation of precursor citrate-capped AuNPs via ligand displacement. However, the molecular-level structural characteristics of the citrate overlayer adsorbed at the aqueous Au interface at neutral pH remain largely unknown. Access to atomistic-scale details of these interfaces will contribute much needed insight into how AuNPs can be manipulated and exploited in aqueous solution. Here, the structures of such citrate overlayers adsorbed at the aqueous Au(111) interface at pH 7 are predicted and characterized using atomistic molecular dynamics simulations, for a range of citrate surface densities. We find that the overlayers are disordered in the surface density range considered, and that many of their key characteristics are invariant with surface density. In particular, we predict the overlayers to have 3-D, rather than 2-D, morphologies, with the anions closest to the gold surface being oriented with their carboxylate groups pointing away from the surface. We predict both striped and island morphologies for our overlayers, depending on the citrate surface density, and in all cases we find bare patches of the gold surface are present. Our simulations suggest that both citrate-gold adsorption and citrate-counterion pairing contribute to the stability of these citrate overlayer morphologies. We also calculate the free energy of adsorption at the aqueous Au(111) interface of a single citrate molecule, and compare this with the corresponding value for a single arginine molecule. These findings enable us to predict the conditions under which ligand displacement of surface-adsorbed citrate by arginine may take place. Our findings represent the first steps toward elucidating a more elaborate, detailed atomistic-scale model relating to the biofunctionalization of citrate-capped AuNPs.
Language eng
DOI 10.1021/la503690t
Field of Research 030302 Nanochemistry and Supramolecular Chemistry
030304 Physical Chemistry of Materials
030704 Statistical Mechanics in Chemistry
Socio Economic Objective 970103 Expanding Knowledge in the Chemical Sciences
HERDC Research category C1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2014, American Chemical Society
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