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Published on: August 9, 2022
Engineering stable wax-based w1/O/W2 double emulsions for high-payload encapsulation, osmotic resistance, and
Mohamed Elhassan1, Guillaume Conzatti2, Halina Anton3
1INSERM (French National Institute of Health and Medical Research), UMR 1260, Regenerative Nanomedicine (RNM), Université de Strasbourg F-67000 Strasbourg, France; Department of Pharmaceutics, Faculty of Pharmacy, University of Gezira, Wad Medani 21111, Sudan.
We engineered wax-shelled double emulsions for stable storage and triggered release of hydrophilic actives. These novel formulations prevent leakage under osmotic stress and release contents upon heating.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Pharmaceutics
Background:
- Water-in-oil-in-water (w1/O/W2) double emulsions offer high encapsulation of hydrophilic actives but suffer from leakage due to osmotic gradients.
- Premature release limits the utility of high-payload hydrophilic formulations during handling and administration.
Purpose of the Study:
- To engineer storage-stable, gel-cored w1/O/W2 double emulsions with temperature-triggered permeability.
- To achieve high internal water fraction (70%) while maintaining formulation integrity.
Main Methods:
- Preparation of double emulsions with a gelled inner aqueous phase and liquid oil or semi-crystalline wax middle phase.
- Characterization using confocal microscopy, release assays (NaCl, metformin), Weibull kinetic modeling, and oscillatory rheology.
- Investigation of iso-osmotic conditions and thermal stimulation for release control.
Main Results:
- Iso-osmotic formulation ensured high initial encapsulation and compartmentalization.
- Wax-shelled systems demonstrated minimal leakage at 25°C and triggered release upon heating to 37°C.
- Wax systems showed stronger retention than liquid oil but some trapping post-triggering; rheology quantified thermal-responsive mechanical changes.
Conclusions:
- Wax-shelled, gel-cored double emulsions provide a promising platform for stable, high-payload hydrophilic formulations.
- Temperature-triggered permeability offers a mechanism for controlled release, overcoming limitations of osmotic instability.
- The developed system demonstrates potential for applications requiring controlled delivery of water-soluble actives.
