Scheme 1.

Fuel‐driven redox‐responsive hydrogel which can autonomously assemble and disassemble in the presence of d‐glucose. The supramolecular hydrogel is comprised of a polyacrylic acid (pAA) backbone with host β‐cyclodextrin (CD) and guest ferrocene (Fc) integrated in a noncovalent polymer network. The hydrogel disassembles by addition of enzyme horse radish peroxidase (HRP) and oxidation fuel H₂O₂ by oxidizing Fc into ferrocenium ion (Fc⁺). This sol can be transformed back into gel by addition of the enzyme glucose oxidase (GOx) and reduction fuel d‐glucose by reducing Fc⁺ back to Fc. Up to a threshold concentration of added d‐glucose, the hydrogel remains stable, while at higher concentrations the hydrogel shows a non‐equilibrium response by autonomously generating oxidation fuel, H₂O₂, for re‐oxidation. This negative feedback leads to conversion of gel into sol which can reassemble back into gel by sole addition of d‐glucose, since both enzymes remain catalytically active.