Cs. Kotsmár

University of California, Berkeley

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R. Miller

Technical University of Darmstadt

J. Krägel

Max Planck Institute of Colloids and Interfaces

E.V. Aksenenko

A.V. Dumansky Institute of Colloid and Water Chemistry

V. B. Fainerman

Donetsk National Medical University

Vincent Pradines

Centre National de la Recherche Scientifique

Martin E. Leser

University of Fribourg

Dmitry Grigoriev

Fraunhofer Institute for Applied Polymer Research

V.S. Alahverdjieva

Max Planck Institute of Colloids and Interfaces

Elena Mileva

Bulgarian Academy of Sciences

R. Wüstneck

Max Planck Society

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Max Planck Institute of Colloids and Interfaces

Max Planck Society

Sharif University of Technology

Lafayette College

University of California, Berkeley

Bulgarian Academy of Sciences

Institute of Physical Chemistry

University of Potsdam

A.V. Dumansky Institute of Colloid and Water Chemistry

Concordia University

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

R. Miller E.V. Aksenenko V.S. Alahverdjieva V. B. Fainerman Cs. Kotsmár

This chapter describes the equilibrium state of mixed protein/surfactant adsorption layers and the mechanisms of their formation by thermodynamic and kinetics theories. Measurements of the equilibrium adsorption state are surface or interfacial tension isotherms. While tensiometry allows following the formation of adsorption layers over a certain time interval, dilational rheology provides information on the response of the interfacial layer to small perturbations. There are additional studies which do not provide quantitative but qualitative information about protein adsorption layers. Surface and interfacial shear rheology, for example, probes the formation of structures within the adsorption layers. The chapter also shows that the general features of protein adsorption at the water—air surface and at water—oil interfaces are similar; however, there are significant quantitative differences. This is of great relevance as proteins and their mixtures with low-molecular-weight surfactants are frequently used for the stabilization of foams and emulsions.

10.1002/9781118523063.ch20

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Citations (8)

Equilibrium of Adsorption of Mixed Milk Protein/Surfactant Solutions at the Water/Air Interface

Langmuir (2008)

Cs. Kotsmár Dmitry Grigoriev Feng Xu E.V. Aksenenko V. B. Fainerman

Ellipsometry and surface profile analysis tensiometry were used to study and compare the adsorption behavior of beta-lactoglobulin (BLG)/C10DMPO, beta-casein (BCS)/C10DMPO and BCS/C12DMPO mixtures at the air/solution interface. The adsorption from protein/surfactant mixed solutions is of competitive nature. The obtained adsorption isotherms suggest a gradual replacement of the protein molecules at the interface with increasing surfactant concentration for all studied mixed systems. The thickness, refractive index, and the adsorbed amount of the respective adsorption layers, determined by ellipsometry, decrease monotonically and reach values close to those for a surface covered only by surfactant molecules, indicating the absence of proteins from a certain surfactant concentration on. These results correlate with the surface tension data. A continuous increase of adsorption layer thickness was observed up to this concentration, caused by the desorption of segments of the protein and transforming the thin surface layer into a rather diffuse and thick one. Replacement and structural changes of the protein molecules are discussed in terms of protein structure and surface activity of surfactant molecules. Theoretical models derived recently were used for the quantitative description of the equilibrium state of the mixed surface layers.

Ellipsometry

Surface pressure

10.1021/la802335g

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Simultaneous versus Sequential Adsorption of β-Casein/SDS Mixtures. Comparison of Water/Air and Water/Hexane Interfaces

ACS symposium series (2012)

A. Dan G. Gochev Cs. Kotsmár J. K. Ferri Aliyar Javadi

This chapter is dedicated to the surface properties of mixed protein/surfactant adsorption layers, formed by two different experimental approaches, i.e. by sequential and simultaneous adsorption, respectively. A special modification of a drop profile analysis tensiometer, consisting of a coaxial double capillary, provides a unique protocol for studies of mixed surface layers formed by sequential adsorption of the individual components in addition to the traditional simultaneous adsorption from their mixed solution. A CFD simulation allowed to optimize the drop exchange process performed with the special double capillary arrangement. The experiments show that properties of sequentially formed layers differ significantly from those formed simultaneously, which can be explained by the different nature and structure of the complexes formed at the two different locations. The nature of the interface, water/air or water/oil, influences strongly the adsorption behavior of the protein molecules and consequently the mixed layers due to their different degree of polarity and hydrophobicity. Washing out experiments are performed in order to support the proposed mechanism of the protein displacement process from mixed surface layers, i.e., to check how many protein molecules are left in the adsorption layer. Based on the experimental studies of the milk protein β-casein (βCS) mixed with the anionic surfactant sodium dodecyl sulfate (SDS) at water/air and water/hexane interfaces, the results are discussed according to different mechanisms describing the different location of interaction.

Sodium dodecyl sulfate

Protein Adsorption

10.1021/bk-2012-1120.ch007

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Dilation and Shear Rheology of Mixed β-Casein/Surfactant Adsorption Layers

The Journal of Physical Chemistry B (2008)

Cs. Kotsmár J. Krägel V.I. Kovalchuk E.V. Aksenenko V. B. Fainerman

The present study deals with dilational and shear rheological properties of adsorption layers of the milk protein beta-casein (BCS) mixed with the nonionic dodecyl dimethyl phosphine oxide (C12DMPO) and the positively charged dodecyl trimethyl ammonium bromide (DoTAB), respectively. The drop profile analysis tensiometer PAT-1 was applied for the dilational rheological studies at low frequency harmonic relaxations. A special modification of the setup, consisting of a coaxial capillary combined with a double dosing system, provides exchange of the drop volume during experiments. This arrangement offers a unique protocol for studies of mixed surface layers, formed by sequential adsorption of the individual compounds. The dilational viscoelastic modulus and the dilational viscosity of the mixed layers, built-up in the two different ways, were investigated and compared. The features of the mixed surface layers drawn from the dilational rheology are qualitatively confirmed by the shear rheological parameters measured by torsion shear rheometry ISR-1. Recently derived theoretical models were used for a quantitative description of the equilibrium state and dilational rheology of the surface layers formed by the single components and their mixtures.

Dilation (metric space)

10.1021/jp807197s

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Citations (49)

Drop profile analysis tensiometry with drop bulk exchange to study the sequential and simultaneous adsorption of a mixed β-casein /C12DMPO system

Colloid & Polymer Science (2008)

Cs. Kotsmár Dmitry Grigoriev A.V. Makievski James K. Ferri J. Krägel

The formation of mixed protein/surfactant adsorption layers is studied by the drop profile analysis tensiometry equipped with a special tool for drop volume exchange during experiments. This arrangement allows investigating in the traditional way by simultaneous adsorption from a mixed solution and also by a subsequent adsorption of the protein followed by surfactant. The experiments are performed for β-casein as the protein in the presence of different amounts of the non-ionic surfactant C12DMPO. The surface layers formed via the two routes show similar equilibrium surface properties. However, the dynamics of desorption of the protein complexes into the pure buffer solution deviate significantly, which is explained by the different locations of the protein/surfactant interaction. Although in both cases the complex formation is based on hydrophobic interaction, the accessibility of the hydrophobic parts of pre-adsorbed proteins due to unfolding is more favourable by the surfactant than in the solution bulk. Therefore, the amount desorbed from surface layers formed from mixed solutions is significantly less as compared to the displacement of proteins by subsequently injected surfactants interacting at the surface.

10.1007/s00396-008-1872-4

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Citations (47)

Equilibrium and dynamics of adsorption of mixed β-casein/surfactant solutions at the water/hexane interface

Colloids and Surfaces A Physicochemical and Engineering Aspects (2009)

Cs. Kotsmár E.V. Aksenenko V. B. Fainerman Vincent Pradines J. Krägel

Hexane

Ammonium bromide

Cationic polymerization

Elasticity

10.1016/j.colsurfa.2009.04.025

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