Structure of Electrical Double Layer at the Metal Oxide with Proteins/NaCl Electrolyte Solution Interface

Adsorption of proteins on metal oxides is important in many fields of life. We carried out studies on deposition (adsorption) of proteins (bovine serum albumin, BSA) on oxides at different pH values (2.5, 4.8 and 7). The oxide samples were of the SiO2/BSA, ST20(SiO2/TiO2)/BSA and SA1(SiO2/Al2O3)/BSA types. NaCl solution was used as a basic electrolyte. It was found that the adsorption of BSA-type protein on the surface of studied oxides changes the character of functional groups that are responsible for charge formation at the adsorbent/electrolyte solution interface, eventually causing a shift of isoelectric point towards higher pH values. The effect of change of functional groups surface properties depends on pH at which the protein was deposited on the matrix surface.