Post‐Assembly Filling of Supported Lipid Bilayers by Soluble Lipid Derivatives

Supported lipid bilayers ( SLB ) are widely used model biological membranes formed on glass or silica surfaces. Though subtle differences from the properties of free‐standing membranes have been reported, its integrity and completeness is seldom questioned. In this report, we show that several different molecules, including some dye‐labeled lipids, can insert from water into preformed and seemingly complete bilayers. The amount of insertion and the bilayer properties after filling were analyzed by a fluorescence bleaching/quenching experiment. The nature of this post‐assembly saturation of SLB is discussed and supported by comparative experiments. This counter‐intuitive but very reproducible result may help to further understand this model bilayer system.