Centre d’Élaboration de Matériaux et d’Etudes Structurales (UPR 8011)


Accueil > Recherche > SINanO : Surfaces, Interfaces et Nano-Objets > Thématiques de Recherche

Interaction between a surface and an atom, a molecule or an organic medium

SINanO Highlights


Adsorption energy of small molecules on core-shell Fe@Au nanoparticles  : tuning by shell thickness

Magali Benoit, Nathalie Tarrat and Joseph Morillo

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The adsorption of several small molecules on different gold surfaces, Au(001), strained Au(001) and Au(001) epitaxied on Fe(001), has been characterized using density functional theory. The surface strain leads to a less energetically favourable adsorption for all studied molecules. Moreover, the presence of the iron substrate induces an additional decrease of the binding energy, for 1 and 2 Au monolayers. For carbon monoxide CO, the structural and energetic variations with the number of Au monolayers deposited on Fe have been analyzed and correlated with the distance between the carbon atom and the gold surface. The effect of the subsurface layer has been evidenced for 1 and 2 monolayers. The other molecules show different quantitative behavior depending on the type of their interaction with the gold surface. However, the iron substrate weakens the interaction, either for the chemisorbed species or for the physisorbed ones. 2 Au monolayers seems like the best compromise to decrease the reactivity of the gold surface towards adsorption while preventing the Fe oxidation.

 


The gold/ampicillin interface at the atomic scale

N. Tarrat, M. Benoit, M. Giraud, A. Ponchet and M. J. Casanove

Publisher’s PDF

In the fight against antibiotic resistance, gold nanoparticles (AuNP) with antibiotics grafted on their surfaces have been found to be potent agents. Ampicillin-conjugated AuNPs have been thus reported to overcome highly ampicillin-resistant bacteria. However, the structure at the atomic scale of these hybrid systems remains misunderstood. In this paper, the structure of the interface between an ampicillin molecule AMP and three flat gold facets Au(111), Au(110) and Au(100) has been investigated with numerical simulations (dispersion-corrected DFT). Adsorption energies, bond distances and electron densities indicate that the adsorption of AMP on these facets goes through multiple partially covalent bonding. The stability of the AuNP/AMP nanoconjugates is explained by large adsorption energies and their potential antibacterial activity is discussed on the basis of the constrained spatial orientation of the grafted antibiotic.