Micropipet-assisted formation of microscopic networks of unilamellar lipidbilayer nanotubes and containers

We describe a novel micropipet-assisted technique for the construction of c omplex, surface-immobilized two-dimensional microscopic networks of unilame llar phospholipid bilayer vesicles (1-50 pm in diameter, 10(-15)-10(-12) L) interconnected by lipid nanotubes (100-300 nm in diameter). As starting ma terial for the construction of networks, we used twinned vesicle pairs, one of which is multilamellar and functions as a membrane donor and the other unilamellar and functions as a membrane acceptor upon manipulation. By elec tromechanical insertion of a pipet tip into the unilamellar vesicle followe d by lateral pulling of the micropipet away from the vesicle, a nanotube wa s formed. Buffer solution contained in the pipet was then injected into the nanotube orifice, forming a vesicle of controlled size that was immobilize d on the surface. The networks have controlled connectivity and are well-de fined with regard to the container size, angle between nanotube extensions, and nanotube length. The internal fluid composition of individual vesicles is defined during the formation of a network by selection of the solution contained in the micropipet.