Quercetin encapsulation and release using rapid CO₂-responsive rosin-based surfactants in Pickering emulsions

Emulsion-based delivery systems are extensively employed for encapsulating functional active ingredients, protecting them from degradation, and enhancing bioavailability and release efficiency. Here, a CO₂-responsive surfactant synthesized from rosin displays rapid responsiveness to CO₂ at room temperature, transitioning reversibly switches between active and inactive states multiple times. The dual tertiary amines on the rosin rigid structure contributes to its CO₂ sensitivity. When in its active cationic form, in conjunction with silica nanoparticles, it exhibits desired Pickering emulsification performance across various oil phases. In the Pickering emulsion loaded with quercetin, the encapsulation efficiency and loading efficiency reached 80.50% and 0.69%, respectively, with stability lasting at least 30 days. The system provides robust protection for quercetin against external factors, such as UV and heat, revealing sustained release effects. This study investigated the potential of using rosin-based CO₂-responsive surfactants alongside nanoparticles to design stable Pickering emulsion systems for active substance encapsulation and sustained release.