Langmuir, Vol.16, No.26, 10301-10308, 2000
Formation and characterization of planar phospholipid bilayers supported on TiO2 and SrTiO3 single crystals
Supported phospholipid bilayers have been prepared on rutile TiO2 and SrTiO3 single-crystal substrates. Fluidlike bilayers were successfully deposited onto each surface by Langmuir-Blodgett and Langmuir-Schaeffer methods and the vesicle adsorption and fusion method. The characteristics of membranes supported on TiO2 and SrTiO3 single crystals were evaluated using fluorescence pattern photobleaching recovery, fluorescence imaging, and differential interference contrast imaging, and the results were compared to similar preparations on fused silica. Diffusion coefficients of a fluorescent lipid in membranes supported on all substrates;were on the order of 10(-8) cm(2)/s, and fractional mobilities were 74-99%: Measured diffusion coefficients were faster for fluorescent lipids in bilayers on TiO2 and SrTiO3 than in bilayers on fused silica, and some sample types exhibited two diffusing species rather than a single diffusing species. Both the intensities and bleachabilities of the fluorescent lipids were significantly reduced for bilayers on TiO2 and SrTiO3 as compared to fused silica. A new theoretical model for interpreting fluorescence pattern photobleaching recovery data for fluorescent lipid diffusion in planar membranes is described. The ability to form planar phospholipid bilayers on TiO2 and SrTiO3 is expected to facilitate new developments in total internal reflection fluorescence microscopy, surface-based assays of importance in biotechnology, and biosensors.