Selective arrangement of vesicles on artificial lipid membrane by biotin-avidin interaction

Lipid bilayers suspended over microwells on Si substrates are promising platforms for nanobiodevices that mimic cell membranes. Using the biotin-avidin interaction, we have succeeded in selectively arranging vesicles on the freestanding region of a lipid bilayer. When ternary lipid mixtures of saturated lipid, unsaturated lipid, and cholesterol are used, they separate into liquid-order (L (o)) and liquid-crystalline (L ( alpha )) domains. A freestanding lipid bilayer prefers the L ( alpha )-phase over the L (o)-phase because of the difference in their flexibility. In addition, the type of biotinylated lipid determines whether it is localized in the L ( alpha )-phase domain or the L (o)-phase domain. As a result, the biotinylated unsaturated lipids localized in the L ( alpha )-phase domain aggregate in the freestanding lipid bilayer, and vesicles labeled with biotin selectively bind to the freestanding lipid bilayer by the biotin-avidin interaction. This technique helps to introduce biomolecules into the freestanding lipid bilayer of nanobiodevices via vesicles.