The complexity of cells makes molecular-scale characterizations of structure and interactions of biomembranes in vivo extremely difficult, thus driving the development of synthetic membrane models. tBLMs are resilient biomimetic systems stabilized by the proximity of an inorganic interface.1,2 We characterize their in-plane structure, dynamics and dielectric properties using fluorescence microscopy, fluorescence correlation spectroscopy (FCS) and electrochemical impedance spectroscopy (EIS). The in-plane dynamics of tBLMs depend on structural details of the anchor lipid and its lateral density in the bilayer leaflet proximal to the substrate.3 In tBLMs with homogeneous lateral label distributions, the fluidity of the distal leaflet is comparable to that in vesicle membranes (2D diffusion constant, D ∼ 7 μm2/s) while that in the proximal leaflet is moderately reduced (D ∼ 2-3 μm2/s). tBLMs completed with phytanoyl lipids (DPhyPC) show lower label diffusivity than those completed with unsaturated chains (DOPC). In laterally heterogeneous bilayers, the label diffusivity varies only slightly, indicating that distinct regions in the bilayers do not correspond to distinct phases. Concurrently, we investigate the effect of charged lipids (DOPS) and cholesterol on lipid diffusivity. This aims at a characterization of changes in membrane dynamics as amyloid-β (Aβ) oligomers associate with tBLMs where they have been shown to affect the resistance of the bilayer to ion conduction.4,5Supported by the NIH (1P01AG032131) and the AHAF (A2008-307).1McGillivray, D.J., et al. 2007. Biointerphases 2:21-33.2Vockenroth, I.K., et al. 2008. Biointerphases 3:FA68-73.3Shenoy, S., et al., 2009. Soft Matter, submitted.4Arispe, N., et al., 1993. Proc. Natl. Acad. Sci. U.S.A. 90:567-571.5Valincius, G., et al., 2008. Biophys. J. 95:4845-4861.