Molecular transmembrane transport with giant unilamellar vesicles (GUVs)

Abstract

Giant vesicles provide a useful model system for measuring a variety of physical properties of lipid membranes and for improving our understanding of the electropermeabilization and electrofusion phenomena. The purpose of this chapter is to present the ways GUV can be formed and submitted to electric pulses. Moreover, it summarizes the presently known effects of electric fields on giant vesicles and some of their practical applications. Subjecting GUVs to DC pulses can destabilize the lipid bilayer, inducing different behavior such as deformation of the vesicles, permeabilization, and motion of domains or fusion that can be directly observed under a microscope. In addition to usual optical microscopies, a number of approaches can be used to assayed molecular transport are described, including micromanipulation, patch-clamp, and CARS spectroscopy. Electric pulses can have dramatic consequences on membrane structure and function. With suitable electric field parameters, it is possible to electropermeabilize the membrane leading to exchange of molecules between the inside and the outside of the vesicle. If the electropermeabilization is strong enough, membrane vesicles, tubules, and macropores can be visualized and are in general accompanied with loss of lipid membrane material and a subsequent GUV size decrease. GUV can therefore be considered as useful tools for resolving the effect of electric fields on cells, even if they present some clear limits in particular for the transport of plasmid DNA.