Adsorption of protein on plasma-polysiloxane layers of different surface energies

We have studied the influence of the surface energy of the substrate to the adsorption of the protein albumin from an aqueous solution. Therefore, coatings of polysiloxane of different surface energies were deposited in a plasma process and used as substrates. The adsorption of the protein albumin on this layers was studied by infrared spectroscopy and wetting analysis, i. e. the determination of the change of the interfacial tension at the solid-liquid interface due to the adsorption by combining contact angle and surface tension data. We found that the amount of adsorbed protein decreased with increasing surface energy of the substrate. The interfacial energy of the solid-liquid interface increases for substrates of high surface energy, which indicates that the decrease of interfacial energy is not the only driving force of this adsorption but also an expulsion of the proteins from the solution takes place (hydrophobic interaction).