Lactose Glicolipids and their Capabilities to form Giant Vesicles and Tubules

Vesicles shape transformations have attracted a attention of researchers due to the possible application the different shapes may have as template systems or vehicles for drug delivery. The common spherical shape of closed bilayer, namely vesicle or liposome, can change into less common structures like starfish, pears, stomatocytes, discocytes or tubules, depending on the bilayer composition or on several parameters like temperature, pH, osmotic pressure, etc. At specific compositions, Giant Unilamellar Vesicles (GUVs) can coexist with nanotubules. There are previous reports of these abilities (vesicle formation and nanotubule transformation) for mixtures of anionic double chain glycophospholipids (incuding galactose, mannose and glucose) with either two hydrocarbon or two perfluorocarbon chains. A ternary system (mixture of sphingomyelin, phosphatidylcholine and cholesterol) for generating emerging long tubular nanostructures has been reported, demonstrating that composition is different in the tubes and in the vesicles and tube split-off depends on phase separation. These results indicate that lipid organization is dependent critically on both membrane curvature and phase separation. We have synthesized a series of glycolipids derived from lactose linked through a glycerol moiety to two alkyl chains of different length (8, 12 and 16 methylene units). Using these glycolipids in combination with POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine), we studied its vesicle-forming capabilities (with and without cholesterol). Using the electroformation method we prepared GUVs and characterized them by two-photon microscopy. Our results showed that all derivatives in combination with cholesterol and POC have the capability to form GUVs and those derivatives with longer alkyl chains besides also form tubular structures coexisting with the giant liposomes when mixed with cholesterol.The authors would like to thank to Fondecyt 1140454 (S.S.) and 1120196 (G.G.) and Beca de postgrado Conicyt 21120554 (C.S.) and Laboratory for Fluorescence Dynamics.