Electrophoretic mobility of a spherical liposome

The electrophoretic velocity of a spherical liposome with a thin double layer is investigated theoretically for the first time to account for a field-induced redistribution of lipid molecules coupled with ion polarization as well as a capacitive effect when the two leaflets of the bilayer have different surface charges. The formulation also incorporates the influence of water osmotic flow through the bilayer. It is found that the lipid redistribution is stronger for a larger liposome, and can give rise to a smaller electrophoretic mobility. For a sufficiently thin double layer, this effect also increases with increasing strength of the imposed electric field. The capacitive effect is significant for the leaflets having very different charge densities, in particular when the outer leaflet becomes nearly uncharged. For such a case, the induction of a surface potential for the outer leaflet is pronounced, leading to electrophoretic migration of the liposome.