Lag-burst kinetics of surfactant displacement from the liquid crystal/aqueous interface by bile acids

    Authors

    S. H. He; J. A. Deng; J. Y. Fang;S. T. Wu

    Comments

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    Abbreviated Journal Title

    Colloid Surf. A-Physicochem. Eng. Asp.

    Keywords

    Bile acids; Surfactants; Liquid crystals; Displacement; Kinetics; SELF-ASSEMBLED MONOLAYERS; CRYSTALS; SALTS; ALIGNMENT; BALANCE; LIPASE; Chemistry, Physical

    Abstract

    Bile acids play an important role in fat digestion by displacing surfactants from the oil-water interface through emulsification. In this paper, we study the time course of the displacement of sodium dodecyl sulfate (SDS) from the liquid crystal (LC)/aqueous interface by four unconjugated bile acids, which differ in the number and position of hydroxyl groups on their steroid backbones. The competitive adsorption of bile acids displaces the SDS from the LC/aqueous interface and consequently triggers a homeotropic-to-tilted anchoring transition of the LC at the interface, which allows the displacement kinetics to be monitored by a polarizing optical microscope. The microscopy image analysis reveals that the displacement exhibits lag-burst kinetics, where a lag phase is followed by a burst phase. We find that the number and position of the hydroxyl groups of bile acids have significant impact on the lag time and burst rate of the displacement kinetics. (C) 2015 Elsevier B.V. All rights reserved.

    Journal Title

    Colloids and Surfaces a-Physicochemical and Engineering Aspects

    Volume

    471

    Publication Date

    1-1-2015

    Document Type

    Article

    Language

    English

    First Page

    148

    Last Page

    152

    WOS Identifier

    WOS:000351918600019

    ISSN

    0927-7757

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