Programmable cross-activity of catalase via functional state engineering in a uricase-catalase cascade nanogel

Catalase (CAT) in peroxisomes undergoes functional switching between detoxification-dominant and metabolism-coupled catalytic modes, driven by substrate availability, redox microenvironment, and heme iron redox state transitions. This dynamic activity transformation enables catalase to function not only as an antioxidant enzyme but also as a regulatory hub integrating ROS signaling, lipid metabolism, and redox homeostasis. Inspired by this natural mechanism, we propose a nanoconfined self-polymerization strategy for the rational design of an oxidase-catalase cascade system, in which the single-molecule-level generation of H₂O₂ is precisely controlled, thereby modulating catalase's substrate-induced functional switching and successfully inducing the transition between its cross-activities of CAT and peroxidase (POD). The activated POD activity drove ˙OH generation, triggering self-limited polymerization to form an in situ cascading enzyme nanogel platform (Gel@UOx/CAT) via uricase (UOx)-CAT cascades. Radical analysis and theoretical calculations confirmed that the functional switching of catalase is governed by reaction field architecture rather than substrate abundance, in which H₂O₂ is generated and channeled in a localized hydrogel network to the active site, and competing catalytic decomposition pathways are kinetically suppressed or spatially segregated. Notably, the prepared confined nanogel relied on its dominant CAT activity to degrade excess pathological H₂O₂, thereby exerting a detoxification-dominated antioxidation effect (Pathway A), and to fulfill the uric acid metabolism-coupled catalysis (Pathway B) simultaneously within the in vivo microenvironment of gout. This paradigm enables precise regulation of enzymatic cross-activities and functional interconversion, offering new opportunities for constructing adaptive biocatalytic systems, artificial metabolic networks, and programmable bioelectronic interfaces.