Interaction between charged lipid vesicles and point- or rod-like trivalent ions

Martin-Molina, Alberto and Lue, Leo and Quesada-Perez, Manuel and Bohinc, Klemen (2019) Interaction between charged lipid vesicles and point- or rod-like trivalent ions. Colloids and Surfaces B: Biointerfaces, 178. pp. 525-529. ISSN 0927-7765 (

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This work examines the influence of the charge distribution of trivalent cations on their interaction with soft anionic particles, using a combination of experimental measurements and theoretical modelling. In particular, we perform electrophoresis measurements to determine the zeta-potential of anionic liposomes in the presence of spermidine and lanthanum cations. We work in a range of electrolyte concentration where a reversal in the electrophoretic mobility of the liposomes is expected; however, unlike the case of lanthanum cations, spermidine does not induce mobility reversal of liposomes. As a result, the charge distribution within the counterion appears to be a key factor. This conclusion is supported by a theory that accounts for intra-ionic correlations, which has previously been successfully used to describe the colloidal electric double layer. It allows us to model spermidine as rod-like ions and lanthanum cations as point-like ions in order to test the importance of the ionic geometry in the interactions with soft particles such as lipid vesicles.