Structure, Preparation, and Applications of Bigels

Bigels are semi-solid, biphasic systems fabricated by the combination of hydrogel and oleogel via high-speed shearing. These systems are characterized by interpenetrating network structures and biphasic continuity. They effectively integrate the biocompatibility and high water content of hydrogels with the mechanical strength and hydrophobic loading capacity of oleogels, thereby surmounting the limitations of single-phase gels. This review systematically delineates the composition (comprising gelling agents, preparation methods, and properties of both hydrogels and oleogels), structural types (oil-in-water, water-in-oil, and bicontinuous), and formation mechanisms of bigels. The key factors influencing the performance of bigels, such as the type and concentration of gelators, water-to-oil ratio, preparation conditions, storage time, and pH, are analyzed. Moreover, the applications in the delivery of bioactive compounds, cosmetics, and food are discussed. The results indicate that bigels display tunable rheological behavior, high stability, and multi-functionality, presenting extensive potential in the food, pharmaceutical, and cosmetic industries. Future research ought to concentrate on enhancing long-term stability, reducing costs, and expanding applications in smart materials and bionic engineering.