Exploring the surface reactivity of Ag nanoparticles with antimicrobial activity: A DFT study

The preferential sites of electrophilic, nucleophilic, and radical attacks on the surface of highly spherical Ag nanoparticles with a diameter of ∼ 2 nm are studied via the Fukui functions and the molecular electrostatic potential; both are calculated using the density functional (DFT) generalized gradient approximation-revised version of the Perdew, Burke, and Ernzerhof level of theory with the double-numerical with polarization functions (DNP) basis set for the valence electrons, and DFT-based semicore pseudopotentials for the core electrons. Because the interaction of Ag nanoparticles with virus and microorganisms takes place in an aqueous environment, the solvent (water) effect is also obtained using the Conductor-like Screening Model. Three typical structures are chosen: cuboctahedral, icosahedral, and ino-decahedral. All three present an "amphoteric" behavior against electrophiles, nucleophiles, and radicals. For the cuboctahedral and decahedral geometries, the highest susceptibility to attack is on the edges shared by a {111} face and a {100} face; for the icosahedral geometry, the highest susceptibility to attack is on the vertices. Ionization potentials, electron affinities, electronegativities, and chemical hardness are also reported. Comparison with experiments is presented.