Interfacial Membranization of Regenerated Cellulose Nanoparticles and a Protein Renders Stable Water‐in‐Water Emulsion

Abstract Pickering water‐in‐water (W/W) emulsions stabilized by biobased colloids are pertinent to engineering biomaterials with hierarchical and confined architectures. In this study, stable W/W emulsions are developed through membranization utilizing biopolymer structures formed by the adsorption of cellulose II nanospheres and a globular protein, bovine serum albumin (BSA), at droplet surfaces. The produced cellulose II nanospheres (NPcat, 63 nm diameter) bearing a soft and highly accessible shell, endow rapid and significant binding (16 mg cm − 2 ) with BSA. NPcat and BSA formed complexes that spontaneously stabilized liquid droplets, resulting in stable W/W emulsions. It is proposed that such a system is a versatile all‐aqueous platform for encapsulation, (bio)catalysis, delivery, and synthetic cell mimetics.