Polylysine Adsorption on Fused Quartz Surface

Abstract

The kinetics of adsorption of two polylysine samples with different molecular weights from aqueous solutions on the surface of fused quartz has been studied by the capillary electrokinetics method. It has been found that the adsorption of positively charged polylysine on the negatively charged quartz surface decreases the absolute value of the initial ζ potential; moreover, in the case of polylysine with the higher molecular weight, it leads to the reversal of the surface charge. The constant values of the ζ potential and the times for which these values are reached depend on the molecular weight and concentration of polylysine. The rate of variations in the ζ potential is highest during the first several minutes of the solution contact with the surface. A decrease in the electric conductivity during polylysine adsorption has, for the first time, been observed, thus leading to a hypothesis that large aggregates are formed on the quartz surface. The measurement of the deformability of the layers has shown that, under our experimental conditions, dense undeformable layers are formed. Polylysines are irreversibly adsorbed on the quartz surface.