Precise control of biphasic droplet symmetry: Nanoparticle-mediated 2D interfacial engineering modulates 3D spatial configuration

Differences in the spatial arrangement of two immiscible phases lead to variations in the symmetry of biphasic droplets, thereby endowing them with diversified 3D spatial configurations. Symmetric core-shell droplets and asymmetric Janus droplets play crucial roles in the food field, including applications in protective encapsulation, controlled release, autonomous motion, particle synthesis, and more. However, comprehending and elucidating the control mechanism of biphasic droplet symmetry in one-step emulsification process remains a daunting challenge. The collision and coalescence behaviors of zein droplets and sodium alginate droplets in 3D space, similar to phagocytosis, create opportunities for the formation of biphasic droplets and the precise control of their symmetry. The interactions between immiscible droplets are closely linked to their 2D interfacial structure. Nanoparticles are utilized as an effective tool to control integrity of 2D interface in monophasic droplets. Therefore, the protein–polysaccharide nanoparticles, fabricated through deamidation and the Maillard reaction, are utilized to regulate the properties of the sodium alginate droplet 2D interface. Variations in the 2D interface structure of the sodium alginate droplets lead to the complete or incomplete engulfment of the sodium alginate droplets by the zein droplets. Ultimately, the nanoparticle-mediated 2D interface engineering modulates 3D spatial configuration of biphasic droplets. This work employs dimensionality reduction theory, using a 2D interface as an anchor point, to achieve symmetry control of biphasic droplets through nanoparticles. It not only lays theoretical foundations for applications of biphasic droplets but also introduces a new research paradigm for the design of functional food colloid structures.