Simultaneous versus sequential adsorption of β-casein/SDS mixtures. Comparison of water/air and water/hexane interfaces

Dan, A ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1021/bk-2012-1120.ch007
  3. Publisher: 2012
  4. Abstract:
  5. 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
  6. Keywords:
  7. Computational fluid dynamics ; Drops ; Experiments ; Molecules ; Proteins ; Sodium dodecyl sulfate ; Adsorption behavior ; Different mechanisms ; Displacement process ; Exchange process ; Experimental approaches ; Individual components ; Protein molecules ; Sequential adsorption ; Adsorption
  8. Source: ACS Symposium Series ; Volume 1120 , 2012 , Pages 153-178 ; 00976156 (ISSN) ; 9780841227965 (ISBN)
  9. URL: http://pubs.acs.org/doi/abs/10.1021/bk-2012-1120.ch007