Versatile and Extendable Boronate-Based Tunable Hydrogel Networks for Patterning Applications

Hydrogel patterning is an emerging area of interest and a valuable tool for studying cellular interactions. However, patterning of hydrogels is normally performed with photo-cross-linkable moieties, severely limiting the choice of materials that can be used. Dynamic covalent cross-linked systems show highly desirable properties as they can show covalent and noncovalent characteristics in response to different environmental conditions, therefore allowing for a potential switch in hydrogel properties. To expand the repertoire of materials suitable for hydrogel patterning, we report versatile pregel polymer networks comprising poly(vinyl alcohol) cross-linked with PEG-diboronates cross-linkers at low ratios. These pregel networks are highly processable and extendable: they can be pulled up into thin strands and used for patterning of thin lines and exhibit both shear thinning and shear thickening properties. The pregels can be easily converted into a hydrogel state by pH adjustment and show clear antibacterial effects. Valuably, the pregels can be integrated into a 3D printing setup to print programmable lines and shapes and subsequently converted into patterned hydrogels. This study demonstrates that dynamic boronate networks can be tuned to exhibit different states and could offer alternate strategies and possibilities for hydrogel patterning applications.