Freeform, Reconfigurable Embedded Printing of All‐Aqueous 3D Architectures

Aqueous microstructures are challenging to create, handle, and preserve since their surfaces tend to shrink into spherical shapes with minimum surface areas. The creation of freeform aqueous architectures will significantly advance the bioprinting of complex tissue-like constructs, such as arteries, urinary catheters, and tracheae. The generation of complex, freeform, three-dimensional (3D) all-liquid architectures using formulated aqueous two-phase systems (ATPSs) is demonstrated. These all-liquid microconstructs are formed by printing aqueous bioinks in an immiscible aqueous environment, which functions as a biocompatible support and pregel solution. By exploiting the hydrogen bonding interaction between polymers in ATPS, the printed aqueous-in-aqueous reconfigurable 3D architectures can be stabilized for weeks by the noncovalent membrane at the interface. Different cells can be separately combined with compartmentalized bioinks and matrices to obtain tailor-designed microconstructs with perfusable vascular networks. The freeform, reconfigurable embedded printing of all-liquid architectures by ATPSs offers unique opportunities and powerful tools since limitless formulations can be designed from among a breadth of natural and synthetic hydrophilic polymers to mimic tissues. This printing approach may be useful to engineer biomimetic, dynamic tissue-like constructs for potential applications in drug screening, in vitro tissue models, and regenerative medicine.