Partners and International Organizations
(English)
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A, B, HR, CZ, DK, FIN, F, D, GR, H, I, NL, N, PL, P, RO, SI, E, S, CH, GB
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Abstract
(English)
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Certain basic aspects in the formation and transformation of vesicles composed of oleic acid and oleate molecules have been investigated on (or close to) a solid surface by using light microscopy. It has been shown that submicrometer-sized vesicles transform into micrometer-sized vesicles, and that the pH as well as the chemical properties of the surface have an influence on these vesicle transformations. It has particulary been found that the adsorption of hydrocarbons onto a glass surface (like squalane) triggers the vesicle fusion process which only occurs on (or close to) the glass surface, while in bulk, the vesicles are stable during the same time of observation, as determined by dynamic light scattering measurements. It is likely that the hydrocarbon molecules taken up by the vesicles lead to a change in the molecular packing parameter (increase in the hydrophobic volume and decrease in the mean molecular head group area), thereby making the vesicles fusogenic (favouring an intermediate reverse hexagonal structure). Similar vesicle transformations have been observed with other fatty acid/soap systems but not with the double-chain phospholipid POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine). It seems that the particular dynamic nature of vesicles from single-chain amphiphiles (such as oleic acid) is essential for the observed hydrocarbon-induced fusion process.
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