Fig. 6. Self-healing functions of the CMC hydrogel crosslinked by the trans-azobenzene/β-CD and the K⁺-ion-stabilized G-quadruplex units: (A) Self-healing of physically connected CMC hydrogel pieces crosslinked by the trans-azobenzene/β-CD units via the cooperative formation of the healed K⁺-ion-stabilized G-quadruplexes. Images show the steps of self-healing and the switchable properties of the resulting healed hydrogel. (B) Self-healing of physically connected CMC hydrogel pieces crosslinked by the K⁺-ions-stabilized G-quadruplexes via the cooperative formation of the healed trans-azobenzene/β-CD units. Images show the steps of the self-healing and the switchable properties of the resulting healed hydrogel.