Programmable Control of Active Ingredient Release in Pickering Emulsions Using Light

Pickering emulsions have garnered significant attention for their ability to facilitate the controlled and effective delivery of active ingredients across various sectors, including drug release, agriculture, cosmetics, and interfacial catalysis. However, achieving the release of encapsulated active substances typically requires the disruption of emulsion droplets, making programmable release a notable challenge. This study develops a colloidal layer with nanogates at the oil-water interface of Pickering emulsion, utilizing UV light as a non-contact, remote stimulus to enable effective programmable release of encapsulated active substances. By alternating UV and visible light irradiation, this work induces cis-trans isomerization of azobenzene molecules on silica particles, allowing the gaps between colloidal particles to open and close. This demonstrated a promising nanogate effect under UV irradiation, facilitating the programmable release of active substance (perylene) from the Pickering emulsion droplets. This Pickering emulsion system offers precise control over the release amount of perylene by adjusting the colloidal particle size and the duration of UV-visible light exposure, all while maintaining emulsion stability. The successful implementation of this strategy presents a promising platform for non-invasive, programmable release of active substances across diverse applications in food, cosmetics and pharmaceutical fields.