Diffusion-induced phase separation 3D printed scaffolds for dynamic tissue repair

Many hydrogen-bonded cross-linked hydrogels possess unique properties,but their limited processability hinders their potential applications.By incorporating a hydrogen bond dissociator(HBD)into these hydrogels,we developed injectable 3D printing inks termed diffusion-induced phase separation(DIPS)3D printing inks.Upon extrusion into water and subsequent diffusion of HBD,these ink cure rapidly.The DIPS-printed scaffold retained most of the original hydrogel properties due to the regeneration of hydrogen bonds.Additionally,the reversible nature of hydrogen bonds provides DIPS 3D-printed scaffolds with exceptional recycling and reprinting capabilities,resulting in a reduction in the waste of valuable raw ink materials or additives.Postprocessing introduces new crosslinking methods that modulate the mechanical properties and degradation characteristics of DIPS scaffolds over a broad range.Based on its suitable mechanical properties and bioactivity,we successfully repaired and functionally reconstructed a complex defect in penile erectile tissue using the DIPS scaffold in a rabbit model.In summary,this approach is relevant for various hydrogen-bonded cross-linked hydrogels that offer mild printing conditions and enable the incorporation of bioactive agents.They can be used as scaffolds for dynamic tissue reconstruction,wearable devices,or soft robots.