Lipid bilayers supported on planar substrates are studied and used extensively because they afford well-defined, biofunctionalizable surfaces with potential application in many areas; among them biosensors, protein dimerization, chromatographic separation, protein immobilization, and study of membrane-membrane interactions. We are interested here in knowing the mobility of individual lipids in supported lipid bilayers – a problem that is physically fundamental and highly related to potential biological sensor functions of supported bilayers.
The interaction between bilayer and protein molecules is of particular interest, since the question is pertinent to the biological process happen on the cell membrane. In this lab, it was already found that under the adsorption of polymer or protein molecules, two kinds of diffusion of lipid diffusion will be present in the bilayer. However, when the bilayer surface is incompletely covered by circular DNA, will there be two modes of diffusion, as protein already induced? If so, what is the mechanism of that? Those are all interesting questions to answer.
Spatially-resolved measurements using dual-color fluorescence correlation spectroscopy (FCS) with two-photon excitation will show whether slaved diffusion happens between membrane associated plasmids and the underlying lipids. In addition, single molecule imaging (SMI) will provide vivid continuous images of the lovely diffusion processes of every single lipid and DNA molecules. What is more, modified single molecule tracking programs will give out their translational diffusion magnitudes accurately, which are well consistent with the FCS results.
