From silk components to emulsions

Abstract

This review is the first to offer a comprehensive exploration of the complex interplay between silk polymorphism, its unique self-assembly properties, and its versatility in forming various silk-based emulsions, with a particular emphasis on the interfacial dynamics at oil/water interfaces. Silk demonstrates remarkable potential as a stabilizing agent through diverse stabilization mechanisms, resulting in the formation of distinct emulsion types. Three primary classes of silk-based emulsions are highlighted: (1) Film-stabilized emulsions, where silk in solution forms an elastic, gel-like 2D film at the oil/water interface; (2) Pickering emulsions, achieved by the adsorption of silk nano-assemblies onto oil droplets; and (3) Emulsion-filled gels, where oil droplets are encapsulated within a gel network using silk's inherent gelling properties. Additionally, the interfacial behaviour of silk—encompassing interfacial rheology and conformational changes—at the oil/water interface is discussed. A detailed analysis of the mechanisms driving silk self-assembly, along with the factors influencing this process, is also provided. The complexity of silk's self-assembly adds significant challenges to the classification of silk-based emulsions and a thorough understanding of their stabilizing mechanisms. Finally, this review addresses existing knowledge gaps and offers potential future directions for advancing research in this area.