Tuneable Hydrogel Porosity via Dynamic Tailoring of Spinodal Decomposition

Pores within hydrogel structures play a crucial role in fostering cell growth and tissue development. The creation and control of pore size and interconnectivity can be conveniently achieved with aqueous two-phase emulsions. The decomposition of these emulsions into two separate phases can be controlled by carefully choosing the polymer components and solution conditions. Spinodal decomposition, a mechanism of phase separation, can result in a highly interconnected pore morphology, though controlling this process is difficult in practice, limiting its application for in vitro models. Here, a straightforward method is introduced for dynamically halting the phase separation of a gelatin methacryloyl and poly(vinyl alcohol) (GelMA-PVA) polymer blend in the context of a biofabrication process based on dynamic interface printing (DIP). This is enabled by a novel approach based on the concerted application of acoustic mixing and photocuring to structure the pore size, orientation, and interconnectivity in hydrogels. This approach accordingly enables spatially addressable fabrication of 3D hydrogel architectures, with the potential to enhance the functionality of engineered tissues via tailored microenvironments.