Figure 1.

Structure and self-healing properties of the CEC-OAHA-MMP hydrogels. a) Network and chemical structures of the RGD-immobilized CEC-OAHA-MMP hydrogel. b) Gelation times of the OAHA-MMP, CEC-OAHA, and CEC-OAHA-MMP hydrogels. c) Storage moduli (G′) of the OAHA-MMP, CEC-OAHA, and CEC-OAHA-MMP hydrogels. Error bars represent standard deviations (n = 3). Significance levels were set at **P < 0.01, ***P < 0.001, and ****P < 0.0001. d) The CEC-OAHA-MMP hydrogel modules stained with gradient blue dye were synthesized in a PDMS mold (i). After combining the modules together and maintaining at 37 °C for 20 min (ii), the hydrogels self-healed, as the integrity and boundaries between different hydrogel modules had nearly disappeared (iii). The self-healed hydrogel could also be handled and lifted without fractures (iv–vi). e) Microscopic observations of the tightly jointed slit (indicated by arrows) between two CEC-OAHA-MMP hydrogel modules. The slit was observed every 3 min, which almost disappeared after 21 min. The scale bar is 100 μm.