Photoactivated Enzymatic Reaction Network Enables Spatiotemporal Programming of Thiol/Disulfide Redox Systems.

Implementing photoactivation into chemical reaction networks (CRNs) offers opportunities for on-demand and remote activation, fuel storage, creating autonomous materials and systems with precise spatial activation. However, examples in this domain remain limited. Here, we introduce a cascaded redox-based enzymatic reaction network (ERN) capable of photoinitiation and refueling, centered around dissipative aromatic disulfide bond formation. To achieve photoinitiation, we integrate an upstream enzymatic module (EM) into the ERN, where the substrate of the EM can be photouncaged using blue light irradiation. A downstream regeneration system enhances the robustness of the reducing environment for repeated fueling. This cascaded ERN operates in solution, allowing for controlled dissipative disulfide formation while avoiding short-circuit reactions (SCR) between the oxidative and reductive halves of the reaction cycle. To showcase the utility of this photoactivated ERN, we couple it with aromatic thiol-terminated star polymers (sPEG-ArSH) to enable spatiotemporally controlled dissipative hydrogel formation using lithographic masks.