Generation of phospholipid vesicle-nanotube networks and transport of molecules therein

We describe micromanipulation and microinjection procedures for the fabrication of soft-matter networks consisting of lipid bilayer nanotubes and surface-immobilized vesicles. These biomimetic membrane systems feature unique structural flexibility and expandability and, unlike solid-state microfluidic and nanofluidic devices prepared by top-down fabrication, they allow network designs with dynamic control over individual containers and interconnecting conduits. The fabrication is founded on self-assembly of phospholipid molecules, followed by micromanipulation operations, such as membrane electroporation and microinjection, to effect shape transformations of the membrane and create a series of interconnected compartments. Size and geometry of the network can be chosen according to its desired function. Membrane composition is controlled mainly during the self-assembly step, whereas the interior contents of individual containers is defined through a sequence of microneedle injections. Networks cannot be fabricated with other currently available methods of giant unilamellar vesicle preparation (large unilamellar vesicle fusion or electroformation). Described in detail are also three transport modes, which are suitable for moving water-soluble or membrane-bound small molecules, polymers, DNA, proteins and nanoparticles within the networks. The fabrication protocol requires ∼90 min, provided all necessary preparations are made in advance. The transport studies require an additional 60-120 min, depending on the transport regime. © 2011 Nature America, Inc. All rights reserved

Repair of large area pores in supported double bilayers

We describe an experimental system where we can generate, and subsequently close, multiple large membrane ruptures in supported double bilayers. We show in this study for the first time that large membrane pores (similar to 10-150 mu m in size) in flat phospholipid vesicles can be reduced in size or completely closed by a pore edge tension driven area reduction mechanism. We can dynamically control the membrane tension of a flat giant unilamellar vesicle and its interplay with the surface adhesion to a solid support. Adhesion to the support surface causes increased membrane tension, which eventually relaxes by the formation of several pores in the membrane. We show that the tension propagation time tau(max) is exceptionally long in this system, which allows for simultaneous opening of multiple pores. The pores can be stabilized by Ca2+-mediated pinning sites in the interior of the flat giant unilamellar vesicle. After pore formation followed by pinning, we depleted Ca2+ ions resulting in removal of pinning and relaxation of membrane tension. This allows the pore to close, driven by the pore edge tension

Generation of phospholipid vesicle-nanotube networks and transport of molecules therein

We describe micromanipulation and microinjection procedures for the fabrication of soft-matter networks consisting of lipid bilayer nanotubes and surface-immobilized vesicles. These biomimetic membrane systems feature unique structural flexibility and expandability and, unlike solid-state microfluidic and nanofluidic devices prepared by top-down fabrication, they allow network designs with dynamic control over individual containers and interconnecting conduits. The fabrication is founded on self-assembly of phospholipid molecules, followed by micromanipulation operations, such as membrane electroporation and microinjection, to effect shape transformations of the membrane and create a series of interconnected compartments. Size and geometry of the network can be chosen according to its desired function. Membrane composition is controlled mainly during the self-assembly step, whereas the interior contents of individual containers is defined through a sequence of microneedle injections. Networks cannot be fabricated with other currently available methods of giant unilamellar vesicle preparation (large unilamellar vesicle fusion or electroformation). Described in detail are also three transport modes, which are suitable for moving water-soluble or membrane-bound small molecules, polymers, DNA, proteins and nanoparticles within the networks. The fabrication protocol requires similar to 90 min, provided all necessary preparations are made in advance. The transport studies require an additional 60-120 min, depending on the transport regime

Generation of phospholipid vesicle-nanotube networks and transport of molecules therein

We describe micromanipulation and microinjection procedures for the fabrication of soft-matter networks consisting of lipid bilayer nanotubes and surface-immobilized vesicles. These biomimetic membrane systems feature unique structural flexibility and expandability and, unlike solid-state microfluidic and nanofluidic devices prepared by top-down fabrication, they allow network designs with dynamic control over individual containers and interconnecting conduits. The fabrication is founded on self-assembly of phospholipid molecules, followed by micromanipulation operations, such as membrane electroporation and microinjection, to effect shape transformations of the membrane and create a series of interconnected compartments. Size and geometry of the network can be chosen according to its desired function. Membrane composition is controlled mainly during the self-assembly step, whereas the interior contents of individual containers is defined through a sequence of microneedle injections. Networks cannot be fabricated with other currently available methods of giant unilamellar vesicle preparation (large unilamellar vesicle fusion or electroformation). Described in detail are also three transport modes, which are suitable for moving water-soluble or membrane-bound small molecules, polymers, DNA, proteins and nanoparticles within the networks. The fabrication protocol requires similar to 90 min, provided all necessary preparations are made in advance. The transport studies require an additional 60-120 min, depending on the transport regime