engleski

The kinetics of adhesion of liposomes on a mercury electrode

The adhesion of liposomes on a mercury electrode leads to capacitive signals due to the formation of islands of lecithin monolayers. Integration of the current-time transients gives charge-time transients that can be fitted by the empirical equation in which the first term describes the docking of the liposome on the mercury surface, the second term describes the opening of the liposome and the third term describes the spreading of the lecithin island on the mercury surface. The temperature dependence of the two time constants and the temperature dependence of the overall adhesion rate allows determining the activation energies of the opening, the spreading, and the overall adhesion process both for gel-phase DMPC and for liquid-crystalline phase DMPC liposomes. In all cases the spreading is the rate determining process. Negative apparent activation energies for the spreading and overall adhesion process of liquid-crystalline phase DMPC liposomes can be explained taking into account weak adsorption equilibria of the intact liposomes, and the opened, but not yet spreaded liposomes. A formal kinetic analysis of the reaction scheme supports the empiric equation used for fitting the charge-time transients. The developed kinetic model of liposome adhesion on mercury is similar to kinetic models published earlier to describe the fusion of liposomes. The new approach can be used to probe the stability of liposome membranes.

adhesion; liposomes; mercury electrode

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