Fig. 3. 3D printing soft hydrogel constructs.

(A) Representative images of 3D printed tubular structures using HAMA⁺ bioinks across various concentrations of HAMA. (B) Comparison of 3D printed tubes before (0 day) and after incubation (1 day in air or PBS) using either 0.5 or 1 wt % HAMA⁺. (C) The compressive moduli of cylinders cast from HAMA formulations (with and without 5 wt % gelatin) across various concentrations before (0 day) and after (1 day) incubation. Two-tailed Mann-Whitney test, *P < 0.05; n.s., not significant (n ≥ 3). (D) Comparison of 3D printed tubes before (0 day) and after incubation (1 day in air or PBS) using 1.5 wt % CSMA⁺ and 1.5 wt % PEGA⁺. Fluorescein-gelatin was used for visualization. Scale bars, 5 mm. Credit for all photographs in this figure: Liliang Ouyang, Imperial College London.