Programmable Control of Active Ingredient Release in Pickering Emulsions Using Light.

Area of Science:

• Colloid and Surface Science
• Materials Science
• Nanotechnology

Background:

• Pickering emulsions are vital for delivering active ingredients in diverse fields like pharmaceuticals and cosmetics.
• Current methods for releasing encapsulated substances often require emulsion disruption, posing a challenge for programmable release.
• A need exists for non-invasive, controlled release mechanisms for active ingredients within stable emulsion systems.

Purpose of the Study:

• To develop a Pickering emulsion system with a light-responsive colloidal layer acting as nanogates.
• To demonstrate programmable release of encapsulated active substances using UV light as a remote stimulus.
• To investigate the control over release kinetics by adjusting system parameters.

Main Methods:

• Fabrication of a colloidal layer with azobenzene-functionalized silica particles at the oil-water interface.
• Utilizing UV and visible light to induce cis-trans isomerization of azobenzene, controlling inter-particle gaps (nanogates).
• Monitoring the release of a model active substance (perylene) under controlled light irradiation cycles.

Main Results:

• Demonstrated a 'nanogate' effect where UV irradiation opened gaps between colloidal particles.
• Achieved programmable release of perylene from Pickering emulsion droplets triggered by UV light.
• Showcased precise control over perylene release amount by tuning particle size and light exposure duration, maintaining emulsion stability.

Conclusions:

• Developed a novel Pickering emulsion system with light-activated nanogates for programmable release.
• The system offers non-invasive, remote control over active substance release using UV-visible light.
• Presents a versatile platform for applications in food, cosmetics, and pharmaceuticals requiring controlled delivery.