Electrostatic Properties of N-Acetyl-Cysteine-Coated Gold Surfaces Interacting with TiO2 Surfaces

It is found that that the coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the TiO2 surface or vice versa by adjusting the electrostatic interactions. In this study, we investigated electrostatic properties of the NAC-coated-gold surface and the TiO2 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 surface potential and charge density dependence on the salt concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface.