Micropipet-Assisted Formation of Microscopic Networks of Unilamellar Lipid Bilayer Nanotubes and Containers

Abstract

We describe a novel micropipet-assisted technique for the construction of complex, surface-immobilized two-dimensional microscopic networks of unilamellar phospholipid bilayer vesicles (1−50 μm in diameter, 10 - 15 −10 - 12 L) interconnected by lipid nanotubes (100−300 nm in diameter). As starting material 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 electromechanical insertion of a pipet tip into the unilamellar vesicle followed by lateral pulling of the micropipet away from the vesicle, a nanotube was formed. Buffer solution contained in the pipet was then injected into the nanotube orifice, forming a vesicle of controlled size that was immobilized on the surface. The networks have controlled connectivity and are well-defined 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.