Encapsulation of biologically active proteins in a multiple emulsion

Area of Science:

• Biotechnology
• Food Science
• Protein Chemistry

Background:

• Oral administration of antibodies like Immunoglobulin Y (IgY) faces stability challenges.
• Emulsion encapsulation is a potential strategy to protect orally administered biologics.
• Understanding protein behavior at oil/water interfaces is crucial for successful encapsulation.

Purpose of the Study:

• To enhance the oral stability of IgY antibodies through W/O/W emulsion encapsulation.
• To investigate the impact of encapsulation on IgY antibody activity and stability.
• To explore the relationship between protein characteristics and inactivation rates during encapsulation.

Main Methods:

• Preparation of stable W/O/W emulsions incorporating 1% IgY using specific emulsifiers (polyglyceryl condensed ricinolate and dextran-casein conjugate).
• Assessment of IgY antibody activity post-encapsulation.
• Electron microscopy to observe IgY adsorption to the emulsion interface.
• Encapsulation and activity assessment of other proteins (Rabbit IgG, alpha-amylase, lysozyme) for comparative analysis.

Main Results:

• A stable W/O/W emulsion with 1% IgY was successfully prepared.
• IgY antibody activity decreased to less than 20% after encapsulation, indicating significant inactivation.
• Electron microscopy confirmed IgY adsorption to the inner water droplet surface (oil/water interface).
• Other tested proteins also showed reduced activity, with inactivation rates correlating to their surface hydrophobicity and molecular stability.

Conclusions:

• W/O/W emulsion encapsulation, while forming stable structures, leads to substantial inactivation of IgY antibodies.
• The oil/water interface is identified as the primary site of IgY denaturation/inactivation.
• Protein inactivation during encapsulation is influenced by inherent molecular properties like surface hydrophobicity and stability.