Fig. 2.

Effect of drying speed and lipid composition. (A) Integrated SAXS data obtained for hydrated GMO/DOTAP/GMOPEG (95/4/1 mol ratio) lipid cakes where chloroform was previously dried at three different pressures (780, 580, and 380 mbar for black, red, and blue lines, respectively). The Bragg peaks correspond to the [110], [200], [211], [310], [222], [321], [400], and [411]/[330] reflections of a bicontinuous primitive Im3m cubic phase. The peaks shift to higher q as drying speed is increased, meaning largest unit cell size (a = 68.4 nm) obtained at the fastest drying speed (380 mbar, blue line). (B) Integrated SAXS data of hydrated lipid samples prepared by nonequilibrium assembly at different lipid compositions. In the GMO/water binary system (black line), primitive and diamond cubic phases (Q_II^P + Q_II^D) of regular spacings are observed. The Bragg peaks Q_II^P and Q_II^D phases are indexed in pink and black, respectively. A 1 mol % addition of GMOPEG induces a phase change into Q_II^P without super-swelling (red line). DOTAP addition (4 mol %, blue line) induces super-swelling of the primitive cubic phase. Decreasing DOTAP content (1.5 mol %, green line) results in a primitive to diamond (Q_II^P → Q_II^D) cubic phase change where both are super-swelled. When DOTAP is substituted with pentavalent lipid MVL5 (GMO/MVL5/GMOPEG 95/4/1, orange line), highly swelled and ordered gyroid phases (Q_II^G) with a = 64.4 nm are observed. A cartoon of the different unit cells (Q_II^P, Q_II^D, and Q_II^G) is represented by the midplane of a lipid bilayer (gray surface) separating two distinct water domains (orange and blue). arb. u., arbitrary units.