Preparation of Planar Lipid Bilayer Membrane by Utilizing Bicelles and Its Characterization

By adding drop-wise a phospholipid bicelle solution, which shows different phase states, onto a glass substrate, a supported lipid bilayer (SLB) that can be used as a biomembrane model was prepared. Bicelles were prepared at differ-ent molar ratios, xDHPC=[DHPC]/([DPPC or DMPC]+[DHPC]), from long-chain phospholipids (DMPC or DPPC) as build bilayer membranes and short-chain phospholipid (DHPC) as a detergent: xDHPC=0.40, and 0.67. Fluorescent lipids (Rhod PE, DiI, or NBD PE) were mixed as probes in each bicelle. The fluorescent probes in the bicelles were observed under a fluorescence microscope for bicelle-derived SLB on a glass substrate at room temperature (ca. 298 K). The formation of the SLBs was confirmed irrespective of the types of long-chain phospholipids and molar ratios; how-ever, more aggregates were formed on the SLB when adding drop-wise onto the glass substrate the DMPC/DHPC bi-celle of xDHPC=0.40 than of xDHPC=0.67. An SLB consisting of a DPPC bilayer membrane was prepared in 5 min by a DPPC/DHPC bicelle. In addition, after mixing a DMPC/DHPC bicelle and a DPPC/DHPC bicelle, they were added drop-wise onto a glass substrate to form an apparently uniform SLB membrane. However, fluorescence spectrum mea-surements suggested that DMPC and DPPC-derived SLB membranes have phase separation.