Imaging Supported Interfacial Layers – Factors that Influence Interface Organization and Dynamics

Supported interfacial structures are centrally important to a variety of electrochemical and chemical sensing applications.  Lipid bilayer structures have received widespread attention not only because of their potential utility in creating biomimetic devices but also because of their inherent complexity and sensitivity to their environment.  Understanding the factors that influence organization and dynamics in such systems could be of immediate relevance to the chemical sensing and biological communities.  Our specific interest lies in the formation of interfaces that could be used to host transmembrane proteins for sensing applications.  Knowledge of the relationships between bilayer composition and morphology, as well as the influence of overlayer constituents, is a necessary first step in the creation of useful supported bilayer interfaces.  We have constructed model bilayer structures containing phosphocholine, sphingomyelin and cholesterol supported on mica, and have examined the organization of and dynamics within these phase-segregated structures using time-resolved fluorescence lifetime and anisotropy imaging.  Our results show that these supported bilayer structures cannot be explained simply in the context of phase segregation of cholesterol and phosphocholine domains, and that the organization of these bilayers depends sensitively on the constituents present in liquid overlayers.  Our image and dynamic data provide a useful starting point for the construction of biomimetic bilayer structures capable of housing biomolecules for sensing applications.