Thermodynamics and Kinetics of Mixed Protein/Surfactant Adsorption Layers at Liquid Interfaces

Adsorption of proteins at the solution/air interface influenced by added non-ionic surfactants at very low concentrations for both components. 1. Dodecyl dimethyl phospine oxide

“…1 (black solid curve for the BCS, red solid curve for BLG) the model for individual solutions of proteins was used as presented in [6,21]. At c S = 0, Eqs.…”

“…The surfactant's molar area ω S and the corresponding adsorption S depend on the surface pressure and the total surface coverage  =  P +  S [6] and are given by:…”

“…The number of bound surfactants per protein molecule depends essentially on the solution pH. The addition of non-ionic surfactants can lead to complexes with proteins probably via hydrophobic interactions and the formation of mixed adsorption layers was described so far mainly by a competitive adsorption mechanism [5][6][7][8]13]. Non-ionic surfactants induce a competitive adsorption phenomenon and lead finally at sufficiently high surfactant concentrations to the replacement of the protein from the interface.…”

Tensiometry and dilational rheology of mixed β-lactoglobulin/ionic surfactant adsorption layers at water/air and water/hexane interfaces

“…This fact is attributed to the stronger cohesive interaction between the organic molecules and the protein's hydrophobic segments which leads to penetration of such segments into the oil phase thus changing the conformation of the protein in the adsorbed state compared to that at the W/A surface. A consequence of that is the attenuation of the intermolecular interaction within the interface which in turn results in lower values of the surface shear [5] and dilational [2][3][4][5][6][7][8][9] moduli for water/oil interface. Lucassen-Reynders et al proposed a relation between the dilational visco-elasticity modulus |E| and the interaction parameter H S in the equation of state for protein adsorption layers as both parameters diminish with decreasing the clean-interface tension c 0 bringing evidence that c 0 is an essential parameter in the visco-elasticity modulus [4,6].…”

“…Concerning the influence of the hydrophobic phase, the adsorption is more intensive at the water/oil interface compared to the water/air (W/ A) surface leading to smaller molar areas [1][2][3][4][5][6][7][8]. This fact is attributed to the stronger cohesive interaction between the organic molecules and the protein's hydrophobic segments which leads to penetration of such segments into the oil phase thus changing the conformation of the protein in the adsorbed state compared to that at the W/A surface.…”