Smart Pickering emulsions stabilized by functionalized nanoparticles: Innovative applications in advanced food packaging

Pickering emulsions (PEs) are dispersions stabilized by solid particles, have excellent stability and the ability to efficiently encapsulate and protect active ingredients sensitive to environment. Solid particles play a critical role in ensuring the stability and functionality of emulsions. Smart PEs with stimuli-responsive can respond to external stimuli such as pH, CO₂, temperature, light and magnetism to regulate the stability of the emulsion (emulsification or demulsification) and smartly control the release of the encapsulated active ingredient, making them highly valued across multiple industries, exceptionally in the preparation of advanced packaging materials. But conventional solid particles cannot endow the ability with stimuli-response to PEs. As a result, surface functionalization emerges as an essential approach for introducing stimuli responsiveness for nanoparticles as stabilizers of Smart PEs. This review introduces the stabilization mechanism and influencing factors of PEs, summarizes the stimuli-responsive mechanisms of nanoparticles for smart PEs and focus on functionalization employed to introduce stimuli responsiveness for nanoparticles. There has been a significant advance in surface modification of nanoparticles, employing the approaches of chemical grafting, electrostatic adsorption, self-assembly, co-precipitation and encapsulation. Meanwhile, the applications of smart PEs in active packaging, indicator packaging, self-healing packaging, and degradable packaging are presented. The current challenges and future directions of smart PEs applying to advanced packaging materials are also outlined. These insights will be invaluable for optimizing functions of smart PEs and broadening their application potential across various fields.