Interaction of Cetyltrimethylammonium Bromide and Sodium Dodecylsulphate with b-lactoglobulin and Lysozyme at Solid Surfaces

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Abstract

The interaction of two ionic surfactants, CTAB and SDS, with β-lactoglobulin and lysozyme at surfaces was monitored by in situ ellipsometry. The effects of the surfactants on proteins adsorbed at a surface as well as the adsorption from protein/surfactant mixtures were studied. The behavior at four different surfaces, silicon oxide, chromium oxide, nickel oxide, and methylated silica, was investigated. The adsorbed amounts of protein were in all cases below or in the range of what would be expected for monolayer adsorption. The elutability of protein seemed to be most complete at the methylated silica surface while for the oxide surfaces the degree of elution was decreasing in the order silica, chromium oxide, and nickel oxide. The effects of surfactants on adsorbed protein films with no protein present in the solution were described according to four adsorption/displacement models: (1) Removal of the protein upon addition of surfactant. (2) Replacement of the protein by the surfactant. (3) Reversible adsorption of the surfactant to the surface with adsorbed protein. (4) Partial removal of protein according to model 1 or 2. When surfactants were premixed with protein prior to adsorption, the interaction between protein and surfactant in solution had to be taken into account. This was reflected in differences in the amounts adsorbed obtained after adsorption as well as after rinse between these experiments and those where surfactant was added after preadsorption of protein. Under certain conditions the presence of surfactant completely prevented protein adsorption.

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  • Food Engineering
Original languageEnglish
Pages (from-to)503-511
Number of pages9
JournalJournal of Colloid and Interface Science
Volume142
Issue number2
Publication statusPublished - 1991
Publication categoryResearch
Peer-reviewedYes