Fig. 2.
Alginate hydrogels employing two-stage crosslinking are effective self-healing and cell-protective bioinks for creating alginate expansion lattices. A. Effective bioinks are created using two-stage crosslinked alginate. First-stage crosslinks produce a weak gel that prevents NPC sedimentation and protects cells from mechanical damage during printing. Second-stage crosslinks determine the final bioink modulus. B. First-stage crosslinking produces a low shear storage modulus that increases 40-fold following second-stage crosslinking. C. First-stage crosslinked alginate bioinks shear-thin upon application of high shear rates and quickly recover after removal of high shear rates. D. Alginate bioinks self-heal and quickly recover their mechanical properties after a disruptive shear event. E. No significant cell sedimentation was observed in alginate bioinks after 1 h. With first-stage (+1st) crosslinking: δ = 1.01 ± 0.01, without first-stage (−1st) crosslinking: δ = 1.03 ± 0.03. F, G. Live/Dead is used to quantify membrane damage following print extrusion. First-stage crosslinked alginate bioinks better protect NPCs during extrusion compared to alginate without first-stage crosslinks.