Hierachically Organized Aqueous Dispersions

Aqueous sub-micron sized dispersions of the binary monolinolein/water system, which are stabilized by means of a polymer, internally possess a distinct nano structure. Taking this as our starting point, we were able to demonstrate for the first time that the internal structure of the dispersed particles can be tuned by temperature in a reversible way. Upon increasing the temperature, the internal structure undergoes a transition from cubic via hexagonal to fluid isotropic, so called L2 phase and vice versa. Intriguingly, in addition to the structural changes in topology, the particles expel (take up, swelling) water to (from, deswelling) the aqueous continuous phase when increasing (decreasing) the temperature in a reversible way. At each temperature, the internal structure of the dispersed particles corresponds very weIl to the structure observed in non dispersed binary monolinolein with excess water. This agreement is independent of any thermal history (including phase transitions), which proves that the structures in the dispersed particles actually are in thermodynamic equilibrium with the surrounding water phase. These nanostructured aqueous dispersions offer a useful approach in the development of novel food and pharmaceuticals applications, such as drug delivery, solubilization of active molecules, selective molecular transport, biosensors, solubilization and crystallization of proteins, or utilization of these systems as nanoreactors for water sensitive reactions and so forth. They are interesting for many reasons, since they give, e.g., the possibility to create hierachically structured particles by using for instance ultrasonication (easy to prepare and to control), and the possibility to tune their confined structures reversibly in a dispersion that is formed with kinetic stability. Our aim in the future study is to understand the effect of the solubilization of hydrophobic guest molecules on the internal structure of our nanostructured MLO-based ECP, EHP, and ELP aqueous dispersions. We will study the effect of linear saturated hydrocarbons (CnH2n2) with different chain lengths and oil-soluble additives (vitamins and antioxidants) on the internal structural changes of our dispersions. lt is of special interest also from both scientifle and applicational point of view to study the possibility of the formulation of an emulsified microemulsion system.