Lipid Transfer between Submicrometer Sized Pickering ISAsome Emulsions and the Influence of Added Hydrogel

Abstract

Transfer of lipids between droplets in Pickering emulsions has been studied by time-resolved small-angle X-ray scattering (SAXS). The special features of self-assembled liquid-crystalline phases have been applied to examine the kinetics of internal phase reorganization imposed by lipid release and uptake by the droplets. The findings reveal faster transfer kinetics in Pickering emulsions than in emulsions stabilized with Pluronic F127. It is shown that the transfer kinetics can be accelerated by adding free surfactant to the dispersions and that this acceleration becomes more dominant when micelles are formed. The effect of immobilization of the droplets has been studied by incorporating them into the appropriate hydrogel network. The droplets are arrested, and the transfer slows down significantly at high enough concentrations of the hydrogel where nonergodic systems are obtained.

Facile Dispersion and Control of Internal Structure in Lyotropic Liquid Crystalline Particles by Auxiliary Solvent Evaporation

“…1,2 Thanks to the dual hydrophilic and hydrophobic character of LLC mesophases, and their large amount of interface, a wide variety of hydrophilic, hydrophobic, or even amphiphilic active molecules can be accommodated in the inner structure of LLC delivery systems. 3 The promising potential of LLC mesophases encompasses biodisponibility 4,5 and solubilization of active molecules such as phytosterols. 2 Moreover, recent work indicates that stimuli-triggered phase transitions may help to achieve targeted controlled release of the active load; 6−9 that is why structure control in LLC dispersions is of deep interest.…”

“…The evolution of droplet size before and after evaporation can be analyzed using a simple geometrical model. The volume fraction of solvent ϕ drop and the radius of the droplet r are linked by the relation ϕ drop = 1 − (r 0 /r) 3 , where r 0 is the final size of the droplet when all the solvent has evaporated. Taking hydration into account as the final water volume fraction f h , we find (3) where d nv and d v are the densities of the nonvolatile (including the lyotropic surfactant) and volatile lipids.…”

“…38 The influence of the secondary emulsifier on the solvent transfer rate yields information about the mechanisms involved in the transfer. 3 When following the weight of an opened vial containing a freshly prepared L 2 prehexosome MLO− tetradecane emulsion containing cyclohexane during the solvent evaporation process ( Figure 5A), a two-step pattern is observed, which is characteristic of the free surface evaporation of emulsions with a volatile oil phase. 31,32 The first part of the curve has a steep slope, corresponding to the simultaneous evaporation of both the solvent and water.…”

“…This method enables to focus on the free F127 content while keeping other emulsion parameters, such as the size distribution, fixed. 3 The initial evaporation of the emulsions was monitored under controlled conditions, using a simple setup. The inset in Figure 5A shows examples of initial evaporation curves for cyclohexane-and limonene-containing emulsions, as well as the comparison with a pure F127 solution without any oil phase, taken as a blank for pure water evaporation.…”

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“…7 Later in 1996, Landh and Larsson patented the preparation of particles comprising different types of liquid crystalline phases in their interiors. 8 These stabilized particles with Internally Self-Assembled mesophases are sometimes referred to as ISAsomes [9][10][11] or as in this review simply termed as mesosomes. Applications of the LLC bicontinuous cubic phase containing mesosomes (cubosomes) and the inverted hexagonal phase based mesosomes (hexosomes) have received considerable attention in recent years.…”