title: Adsorption of Bovine Serum Albumin (BSA) at the Oil/Water Interface: A Neutron Reflection Study.
abstract: The structure of the adsorbed protein layer at the oil/water interface is essential to the understanding of the role of proteins in emulsion stabilization, and it is important to glean the mechanistic events of protein adsorption at such buried interfaces. This article reports on a novel experimental methodology for probing protein adsorption at the buried oil/water interface. Neutron reflectivity was used with a carefully selected set of isotopic contrasts to study the adsorption of bovine serum albumin (BSA) at the hexadecane/water interface, and the results were compared to those for the air/water interface. The adsorption isotherm was determined at the isoelectric point, and the results showed that a higher degree of adsorption could be achieved at the more hydrophobic interface. The adsorbed BSA molecules formed a monolayer on the aqueous side of the interface. The molecules in this layer were partially denatured by the presence of oil, and once released from the spatial constraint by the globular framework they were free to establish more favorable interactions with the hydrophobic medium. Thus, a loose layer extending toward the oil phase was clearly observed, resulting in an overall broader interface. By analogy to the air/water interface, as the concentration of BSA increased to 1.0 mg mL(-1) a secondary layer extending toward the aqueous phase was observed, possibly resulting from the steric repulsion upon the saturation of the primary monolayer. Results clearly indicate a more compact arrangement of molecules at the oil/water interface: this must be caused by the loss of the globular structure as a consequence of the denaturing action of the hexadecane.
authors: †Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.|‡Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral CH63 2JW, United Kingdom.
authors: M
authors: M
authors: Campana
authors: ‡Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral CH63 2JW, United Kingdom.
authors: S L
authors: SL
authors: Hosking
authors: §KLK Oleomas SDN BHD, Level 8, Menara KLK, Jalan PJU7/6, Mutiara Damansara, 47810 Petaling Jaya, Selangor Malaysia.
authors: J T
authors: JT
authors: Petkov
authors: ‡Unilever Research and Development Laboratory, Port Sunlight, Quarry Road East, Bebington, Wirral CH63 2JW, United Kingdom.
authors: I M
authors: IM
authors: Tucker
authors: ∥ISIS Neutron Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, United Kingdom.
authors: J R P
authors: JR
authors: Webster
authors: ⊥School of Biological and Chemical Sciences, Queen Mary University of London, Joseph Priestley Building, Mile End Road, London E1 4NS, United Kingdom.
authors: A
authors: A
authors: Zarbakhsh
authors: †Biological Physics Group, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
authors: J R
authors: JR
authors: Lu
mesh_terms: D000818:Animals; D002417:Cattle; D008956:Models, Chemical; D009821:Oils / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D009821:Oils; D014867:Water; D012710:Serum Albumin, Bovine