Lipid swelling and liposome formation mediated by electric fields

Abstract

Electric fields can induce, facilitate or hinder lipid swelling and liposome formation. This paper briefly discusses theoretical and experimental results of the effects of dc fields, and presents new data and estimates for lipid swelling and liposome formation on metal electrodes and glass surfaces in ac fields and for swelling of positively charged lipid mixtures in dc fields. There are four basic conclusions from these results: (1) ac fields can induce liposome formation for lipids swelling on electrode surfaces; (2) the vibrations of lipid structures in ac fields are due to electro-osmotic effects; (3) positively charged lipid mixtures swell faster on the positive electrode than on the negative one and in the absence of a field; and (4) electric fields do not affect lipid swelling and liposome formation on glass surfaces, i.e. when the lipid is not placed on the very electrode. Possible mechanisms of liposome formation and lipid swelling include osmotic, electrostatic, double layer, electromechanical and line tension effects.