Sponge Phases and Nanoparticle Dispersions in Aqueous Mixtures of Mono- and Diglycerides

Abstract

The lipid liquid crystalline sponge phase (L3) has the advantages that it is a nanoscopically bicontinuous bilayer network able to accommodate large amounts of water and it is easy to manipulate due to its fluidity. This paper reports on the detailed characterization of L3 phases with water channels large enough to encapsulate bioactive macromolecules such as proteins. The aqueous phase behavior of a novel lipid mixture system, consisting of diglycerol monooleate (DGMO), and a mixture of mono-, di- and triglycerides (Capmul GMO-50) was studied. In addition, sponge-like nanoparticles (NPs) stabilized by Polysorbate 80 (P80) were prepared based on the DGMO/GMO-50 system, and their structure was correlated with the phase behavior of the corresponding bulk system. These NPs were characterized by dynamic light scattering (DLS), cryo-transmission electron microscopy (Cryo-TEM) and small angle X-ray scattering (SAXS) to determine their size, shape, and inner structure as a function of the DGMO/GMO-50 ratio. In addition, the effect of P80 as stabilizer was investigated. We found that the NPs have aqueous pores with diameters up to 13 nm, similar to the ones in the bulk phase.

Interfacial properties of lipid sponge-like nanoparticles and the role of stabilizer on particle structure and surface interactions

“…This effect is rather pronounced at high P80 concentrations, where even the loss of internal particle structure can occur. 22,25 In our earlier work 13 with the same DGMO/GMO-50/P80/water system as studied here, we were also able to form nanoparticles with highly swollen sponge phase structures over a wider range than in the pure lipid-aqueous system. Cryo-TEM imaging showed that such phases could be dispersed into sponge-like nanoparticles (L 3 -NPs) that featured a dense sponge phase core with swollen bilayer structures at the interface.…”

“…The q 1 value was found to be 0.05 Å À1 , which agrees quite well with the SAXS results where q 1 was 0.047 Å À1 . It should be noted that, in spite of the fact that the dP80 and hP80 used here were from a different batch than the hP80 used for the SAXS and cryo-TEM experiments, 13 we still found similar sponge phases in terms of dimensions and location in the phase diagram. Comparing different solvent contrast, it can be seen that in H 2 O the repeat distances are larger than in D 2 O, as q 1 shift towards lower q-values, both for dP80 and hP80.…”

“…This part of the scattering curve is particularly influenced by the L 3 phase, which is dominant at this particle composition as previously shown from our SAXS and cryo-TEM results. 13 Fig. 2 depicts the experimental and fitted scattering curves of L 3 -NPs with hP80 and dP80 at different solvent contrast and dilutions.…”

“…More recently, the lipid sponge phase (L 3 ) has attracted more attention due to its flexibility and capacity for forming large aqueous pores able to encapsulate large bioactive molecules. 5,13,14 This is more challenging to obtain with other reverse mesophases (cubic or hexagonal), where the cell dimensions are usually smaller or require the use of organic solvents or specific environmental conditions (temperature or pressure). [15][16][17] The interfacial properties of cubosomes and hexosomes have been examined to understand the nature of the interactions between these LCNP and different interfaces that mimic storage or administration vessels, such as glass vials, catheters or syringes.…”

Curcumin- and Fish Oil-Loaded Spongosome and Cubosome Nanoparticles with Neuroprotective Potential against H2O2-Induced Oxidative Stress in Differentiated Human SH-SY5Y Cells

“…The latter were evidenced by smooth SAXS curves typical for sponge-type lipid particles. 90,92 The presence of Braggs peaks in Figure 2a,b characterized the nanocarriers with a periodic inner organization (cubosomes). The determined lattice parameters of the coexisting cubic unit cells in the Pn3m cubosome particles are a 1 = 21.1 nm and a 2 = 16.4 nm ( Figure 2b).…”