An expressed goal of our research is to understand how bio-surfactants populate gas-liquid and solid-liquid interfaces so that we may ultimately exercise control over the molecular composition of the interface to confer the desired physiological and mechanical properties. Biological systems inherently require an understanding of competitive adsorption from high concentration solutions. Our experiments indicate that multi-species systems can exhibit competitive and cooperative surface tension change. While these observations may be explainable by competitive adsorption models derived from the Gibbs equation of state, a mechanistic understanding of this behavior cannot be verified with surface tension data alone. Furthermore, the roles of post-adsorption conformation change, aggregation, or bonding in surface tension change remain unclear. This highlights a need for a method to measure the surface excess concentration directly. We are developing confocal microscopy measurement techniques to image the protein adsorption process, and provide insight into interfacial protein behavior.

Surface tension measurements cannot uniquely define surface excess concentration during competitive protein adsorption

243rd National Meeting (2012)

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