Impact of ionic liquid-type imidazolium surfactant addition on dynamic properties of BSA adsorption layers at different pH.

The dynamic interfacial properties of mixed solutions of bovine serum albumin (BSA) and the ionic liquid-type imidazolium surfactant ([C16mim]Br) were measured as a function of the interface age, surfactant concentration and solution pH. Three BSA conformers were investigated: the normal N form as well as the fast F and aged A forms, corresponding to the different solution pH, respectively. The interfacial tension and the interfacial dilational elasticity isotherms for the mixed adsorption layers indicate that the addition of [C16mim]Br to the different structures of BSA isomers influences the properties of the adsorption layer at the decane/water interface. The addition of [C16mim]Br does not influence the structure of the protein at pH below the isoelectric point of BSA, but at higher solution pH, the addition of surfactants significantly influences the dynamic interfacial properties of BSA solutions due to the electrostatic interaction between the components.