Formation mechanism of self-assembled unilamellar vesicles

Uniform size self-assembled unilamellar vesicles (ULVs) can be produced from mixtures of weakly charged short- and long-chain phospholipids. These lipid mixtures self-assemble into bilayered micelles (so-called bicelles), and a bicelle to ULV transition has been previously reported. Here, we discuss the effect of various parameters (i.e., lipid concentration, charge density, membrane rigidity, lipid composition, and lipid hydrocarbon chain length) on ULV radius as determined by small angle neutron scattering (SANS). SANS data were best fit using a core-shell disk and a spherical-shell model to obtain the size of bicelles and ULVs, respectively. From the present experiments we conclude that a previously proposed mechanism of ULV formation, where bicelles coalesce into large precursor and self-fold into ULVs, is able to explain the present SANS data.Il est possible de produire des v\ue9sicules \ue0 une couche auto-assembl\ue9es et de grosseur uniforme (ULVs), \ue0 partir de m\ue9langes de cha\ueenes de phospholipides courtes et longues faiblement charg\ue9es. Ces m\ue9langes de lipides s\u2019auto-assemblent en micelles bicouches (parfois appel\ue9es bicelles) et une transition de bicelle \ue0 ULV a d\ue9j\ue0 \ue9t\ue9 d\ue9crite. Nous discutons ici l\u2019effet de diff\ue9rents param\ue9tres (la concentration lipidique, la densit\ue9 de charge, la rigidit\ue9 de membrane, la composition lipidique et la longueur des cha\ueenes lipidiques) sur le rayon des ULV qui est d\ue9termin\ue9 par diffusion de neutrons aux petits angles (SANS). Nous ajustons la courbe des donne\ub4es SANS \ue0 l\u2019aide d\u2019un mod\ue8le en couches sph\ue9riques pour obtenir la grosseur des bicelles et des ULV respectivement. \uc0 partir des pr\ue9sentes exp\ue9riences, nous concluons qu\u2019un m\ue9canisme pr\ue9alablement rapport\ue9 sur la formation des ULV, o\uf9 les bicelles coalescent en un gros pr\ue9curseur et s\u2019auto-replient en ULV, est capable d\u2019expliquer les pr\ue9sentes donn\ue9es SANS.Peer reviewed: YesNRC publication: Ye