Electrostatic properties of N-acetyl-cysteine-coated gold surfaces interacting with ZrO ₂ surfaces

The coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the ZrO ₂ surface or vice versa by adjusting the electrostatic interactions. In this study, it was performed to find out electrostatic properties of the NAC-coated-gold surface and the ZrO ₂ surface. The surface forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface forces, the surface potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The dependence of the potential and charge density on the concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface.