Modulated Fringe Pattern Photobleaching Applied to Lipid-water Cubic Phases : Structural Information

We present lateral diffusion experiments performed on lipid-water cubic phases with the purpose of correlating dynamic and structural properties of the system. The experiments involve the modulated fringe panern photobleaching technique : after flashing a bleaching beam, and thus generating a fluorescence heterogeneity, we observed the kinetics of fluorescence recovery. The analysis of the time course of the recovery yields information regarding the lateral diffusion of the fluorescent molecules in the system. We observed different types of diffusion, clearly correlated with the topological properties of the different structures, as established by the previous X-ray scattering studies. For one of the cubic phases (Q223), the results of the fluorescent recovery study appear to be consistent with a structure containing both an open hydrocarbon labyrinth and a family of closed micellar elements, rather than with a model containing only closed micelles.