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Synchrotron small-angle X-ray scattering (SAXS) was applied for studying the effects of hydrostatic pressure and temperature on the structural behavior of fully hydrated tetradecane (TC)-loaded monoolein (MO) systems. Our main attention focused on investigating the impact of isobaric and isothermal changes on the stability of the inverted type discontinuous Fd3mcubic phase as compared to the inverted type hexagonal (H2) liquid crystalline phase. The present results show that compressing the TC-loaded Fd3mphase under isothermal conditions induces a significant increase of its lattice parameter: it approximately increases by 1 Å per 75 bar. Further, the Fd3mphase is more pressure-sensitive as compared to the Pn3mand the H2phases. At ambient temperatures, we observed the following structural transitions as pressure increases: Fd3m→ H2→ Pn3m. Our findings under isobaric conditions reveal more complicated structural transitions. At high pressures, we recorded the interesting temperature-induced structural transition of (Pn3m+ Lα) → (Pn3m+ Lα+ H2) → (Lα+ H2) → H2→ Fd3m→ traces of Fd3mcoexisting with L2. At high pressures and low temperatures, the TC molecules partially crystallize as indicated by the appearance of an additional diffraction peak at q= 3.46 nm−1. This crystallite disappears at high temperatures and also as the system gets decompressed. The appearance of the Pn3mand the Lαphases during compressing the fully hydrated MO/TC samples at high pressures and low temperatures is generally related to a growing hydrocarbon chain condensation, which leads to membrane leaflets with less negative interfacial curvatures (decreasing the spontaneous curvatures |H0|). Both the effects of pressure and temperature are discussed in detail for all nonlamellar phases on the basis of molecular shape and packing concepts. [ABSTRACT FROM AUTHOR]

The inverted-type liquid-crystallinedispersions comprising cubosomesand hexosomes hold much potential for drug solubilization and site-specifictargeting on intravenous administration. Limited information, however,is available on the influence of plasma components on nanostructuraland morphological features of cubosome and hexosome dispersions, whichmay modulate their stability in the blood and their overall biologicalperformance. Through an integrated approach involving SAXS, cryo-TEM,and nanoparticle tracking analysis (NTA) we have studied the time-dependenteffect of human plasma (and the plasma complement system) on the integrityof the internal nanostructure, morphology, and fluctuation in sizedistribution of phytantriol (PHYT)-based nonlamellar crystalline dispersions.The results indicate that in the presence of plasma the internal nanostructureundergoes a transition from the biphasic phase (a bicontinuous cubicphase with symmetry Pn3mcoexistingwith an inverted-type hexagonal (H2) phase) to a neat hexagonal(H2) phase, which decreases the median particle size. Theseobservations were independent of a direct effect by serum albuminand dispersion-mediated complement activation. The implication ofthese observations in relation to soft nanocarrier design for intravenousdrug delivery is discussed. [ABSTRACT FROM AUTHOR]