Figure 2.

Rheological recovery test and procedure for generating modular gradient hydrogel construct by injection. a) The G′ and G″ of the CEC-I-OSA hydrogel from alternate step-strain sweeps with a small strain (γ = 0.1%) for 200 s, followed by a large strain (γ = 800%) for 200 s after healing for 90 s at 37 °C. b) The mixed precursor solutions of the hydrogels containing various concentration of blue dye were placed into the circular PDMS mold, generating the “units.” c,d) The CEC-OAHA-MMP hydrogel units with varying concentration of blue dye were removed from the mold and loaded into a 10 mL syringe. e) The CEC-OAHA-MMP hydrogel units were sequentially injected from needles (indicated by arrows) to generate gradient hydrogel constructs with different needle diameters (0.7 and 1.4 mm), gradient distributions (i, ii, and iii) and “S” shapes (iv).