The physical and chemical properties of gold nanoparticles (AuNPs) are critical to many applications, such as for developing new materials and medicines. In this work, we report the electric potential around citrate-capped gold nanoparticle (cit-AuNP) and poly(allylamine hydrochloride) (PAH)-wrapped cit-AuNP (PAH-AuNP) at various ionic strength. We use all-atom molecular dynamics (MD) simulations to model cit-AuNP and PAH-AuNP at different NaCl concentrations. The electric potential φ(r) at different radius is calculated from the Na+ and Cl- ionic number distributions calculated in MD simulations. We show that the electric potential is affected by the salt concentration. We also report the ζ-potential values at different salt concentrations, using the hydrodynamic radius (RH). In the end, our MD simulation φ(r) result is compared with Poisson-Boltzmann equation (PBE) approximation and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The regimes where the PBE and DLVO theory are satisfied with respect to surface charge, salt concentration and particle size are reported.

Salt Concentration Effect on the Electric Potential of Gold Nanoparticles

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ACS Fall 2022

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