Re-programming Hydrogel Properties Using a Fuel-Driven Reaction Cycle.

Nature uses catalysis as an indispensable tool to control assembly and reaction cycles in vital non-equilibrium supramolecular processes. For instance, enzymatic methionine oxidation regulates actin (dis-)assembly, and catalytic guanosine triphosphate hydrolysis is found in tubulin (dis-)assembly. Here we present a completely artificial reaction cycle which is driven by a chemical fuel that is catalytically obtained from a "pre-fuel". The reaction cycle controls the dis-assembly and re-assembly of a hydrogel, where the rate of pre-fuel turnover dictates the morphology as well as the mechanical properties. By addition of additional fresh aliquots of fuel and removal of waste, the hydrogels can be re-programmed time after time. Overall, we show how catalytic fuel generation can control reaction/assembly kinetics and materials' properties in life-like non-equilibrium systems.