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Protein instability toward organic solvent/water emulsification: implications for protein microencapsulation into
1Department of Pharmaceutical Sciences, University of Tennessee College of Pharmacy, Memphis, USA.
PDA Journal of Pharmaceutical Science and Technology
|May 27, 1999
Summary
Emulsification damages proteins like ovalbumin and lysozyme, forming insoluble aggregates. Ethyl acetate is gentler than methylene chloride, highlighting the need for protein stability during microencapsulation.
Area of Science:
- Biochemistry
- Materials Science
- Chemical Engineering
Background:
- Protein stability is crucial for microencapsulation processes.
- Water-in-oil-in-water (W/O/W) emulsion techniques are widely used for encapsulation.
- Understanding protein behavior at organic solvent/water interfaces is essential for optimizing these techniques.
Purpose of the Study:
- To investigate the behavior and integrity of proteins at an organic solvent/water interface during W/O/W emulsion preparation.
- To compare the effects of different organic solvents (methylene chloride and ethyl acetate) on protein stability.
- To assess the impact of emulsification on protein aggregation and recovery.
Main Methods:
- Preparation of water-in-oil (W/O) emulsions using aqueous protein solutions in methylene chloride or ethyl acetate.
- Phase separation to collect protein samples from aqueous and interface phases.
- Analysis of protein properties using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion-high-performance liquid chromatography (SE-HPLC).
Main Results:
- Bovine serum albumin (BSA) showed relative stability, while ovalbumin and lysozyme exhibited significant denaturation and aggregation.
- Methylene chloride treatment induced substantial water-insoluble aggregates and altered ovalbumin species.
- Ovalbumin recovery was low (9.74–37.72%) in aqueous phases post-emulsification, with similar trends for lysozyme.
- Ethyl acetate resulted in less severe emulsification-induced denaturation compared to methylene chloride.
- Identified water-insoluble aggregates were covalently bound.
Conclusions:
- Emulsification processes can adversely affect protein integrity, leading to aggregation and reduced recovery.
- Methylene chloride poses a higher risk of protein damage than ethyl acetate during emulsification.
- Maintaining protein stability is critical for successful microencapsulation and preserving protein functionality.