Reconfigurable aqueous 3D printing with adaptive dual locks.

Using aqueous two-phase systems (ATPSs) for three-dimensional (3D) printed complex structures has attracted considerable attention in the field of biomedicine. In this study, we present an unusual approach to constructing reconfigurable 3D printed structures within an aqueous environment. Inspired by biological systems, we introduce both specific and nonspecific interactions to anchor functionalized nanoparticles to the water-water interface, thereby imparting adaptive dual locks of structural integrity and permeability to the 3D printed liquid structures. Using state-of-the-art in situ liquid-liquid interfacial atomic force microscopy imaging, we successfully demonstrate various morphologies of interfacial films formed at the ATPS interface. In addition, by incorporating d-glucose or sodium alginate into the systems, the dual locks can be easily manipulated. Our study paves a pathway for 3D printing multiresponsive all-aqueous systems with controllable structures and permeability, showing promising implications for the development of smart drug delivery systems and in vivo reactions.