Collagen-surfactant mixtures at fluid/fluid interfaces
Aleksandra Kezwoń , Kamil Wojciechowski
AbstractThe effect of three synthetic surfactants on surface activity and surface dilatational rheology of temperature-denatured type I collagen at water/air interface is described. An anionic (sodium dodecyl sulfate, SDS), a cationic (cetyltrimethylammonium bromide, CTAB) and a nonionic (Triton X-100, TX-100) surfactants were employed at variable concentrations (5 × 10−6 mol L−1–1 × 10−4 mol L−1). With the protein concentration fixed at 5 × 10−6 mol L−1, the protein/surfactant mixtures with molar ratios of 1:1, 1:2, 1:3, 1:5, 1:10 and 1:20 were obtained. An Axisymmetric Drop Shape Analysis (ADSA) method was used to determine the dynamic and equilibrium surface tension, as well as the surface dilatational moduli of the mixed adsorption layers formed at the water/air interface at pH 4.5. For the collagen-SDS mixtures, analogous studies were also performed at the water/tetradecane and water/olive oil interfaces. These results were complemented with the foam and emulsion formation ability tests, and the oil-in-water emulsions were characterized using Dynamic Light Scattering (DLS) and visual assessment. The most beneficial effect on surface activity, mechanical properties of adsorbed layer and foaming ability was observed for the mixtures of temperature-denatured collagen with SDS. The rheological parameters of the adsorbed layers formed by the same mixtures at the water/olive oil and water/tetradecane interfaces worsened significantly (values of rheological parameters E’ and E” are lower than values of E’ and E” of the adsorbed layers formed at the water/air interface). The corresponding emulsions, despite very low interfacial tension values, phase-separated within hours. We hypothesize that the poor kinetic stability was caused by flocculation due to collagen bridging between the oil droplets, resulting in emulsion creaming.
|Journal series||Colloids and Surfaces A-Physicochemical and Engineering Aspects, ISSN 0927-7757|
|Publication size in sheets||0.5|
|Keywords in English||Type I calf skin collagen; Denaturation; Surface tension; Surface dilatational rheology; Foam; Emulsion; SDS; CTAB; TRITON X-100|
|Score|| = 30.0, 28-11-2017, ArticleFromJournal|
= 30.0, 28-11-2017, ArticleFromJournal
|Publication indicators||: 2016 = 2.714 (2) - 2016=2.838 (5)|
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