Bovine Serum Albumin Adsorption at a Polarized Water/1,2‐Dichloroethane Interface with No Effect on the Ion Transfer Kinetics

Abstract

AbstractAdsorption of bovine serum albumin (BSA) at a polarized water/1,2‐dichloroethane (DCE) interface is examined by measuring the dynamic interfacial tension at various cell potentials E, BSA concentrations and pH of the aqueous phase (w). An addition of BSA to the phase (w) results in an appreciable decay of with time in the whole potential range available, which follows an induction period at the very beginning of the transient. An analysis of the effect of the BSA concentration on the transients enables to establish the adsorption isotherm, and to evaluate both the maximum surface excess concentration of BSA and the standard Gibbs energy of adsorption. An increase of the potential E results in an acceleration of the adsorption, and an increase of the surface excess concentration of the positively charged BSA at pH 2, while the latter effect is absent when BSA is charged negatively at pH 7.3. It is shown that the adsorbed BSA has a negligible effect on both the interfacial capacitance of the polarized water/DCE interface and the rate constant of the interfacial transfer of the tetraethylammonium (TEA+) or Cs+ ion measured at the corresponding standard ion transfer potential.