Electroporation Dynamics of Giant Vesicles with Encapsulated Gel and in the Presence of Salt or Detergents

Abstract

Electroporation is an efficient method for intracellular delivery. Although popular, the molecular details of this process are not well understood. Studying of various aspects of membrane electroporation using cells is difficult due to their inherent complexity. The use of membrane models such as giant unilamellar vesicles (GUVs) offers the advantage of well-controlled conditions. Strong electric fields induce deformation and poration of GUVs, with a characteristic relaxation time (Trelax) and pore lifetime (Tpore). Here, we investigate the response of GUVs to electric pulses in three different conditions: GUVs encapsulating agarose polymer, and charged GUVs in the presence of NaCl and Triton X-100. Electroporation of vesicles with encapsulated agarose leads to larger values of Tpore and Trelax. For agarose, around 20% of the GUVs expel a gel-like meshwork through the formation of very large pores. Moreover, in most cases the membrane remains permeable to small molecules after macropore closure. These effects do not depend on membrane composition. Negatively charged GUVs in the presence of NaCl display macropores with long lifetime, which quite often lead to vesicle burst as the membrane is transformed into nanotubes along the pore rim. Vesicle bursting and Tpore depend on the fraction of the negatively charged lipid POPG and on [NaCl] (0-5mM). Membrane composition is not altered at the pore rim. In the presence of non-solubilizing concentrations of Triton X-100, electroporation of negatively charged GUVs display a large distribution of Tpore values as compared with Tpore in the absence of Triton X-100 or for neutral GUVs. In summary, Tpore is a suitable parameter in the investigation of various membrane properties under different conditions. Acknowledgments: FAPESP.