Soft catalytic platforms: hydrogel-catalyst synergies for spatiotemporally controlled therapy.

Catalytic hydrogels have recently emerged as a versatile class of soft catalytic platforms that integrate nanocatalysts within hydrated, extracellular matrix-mimicking polymer networks to enable localized and programmable biochemical regulation. By coupling microenvironment-responsive matrices with catalytic centers capable of redox conversion, energy transduction, or cascade reactions, these systems achieve spatiotemporally controlled therapeutic functions beyond conventional drug-based approaches. In this review, we first summarized recent advances in catalytic hydrogels and classified them into four categories based on energy input: autocatalytic, photocatalytic, electrocatalytic, and piezocatalytic hydrogels, and highlighted their distinct catalytic mechanisms. Then, the respective roles of catalysts and hydrogel matrices were discussed, emphasizing that performance arose not only from catalyst design such as single-atom sites, defect engineering, and heterojunctions, but also from matrix-mediated regulation of mass transport, confinement, retention and stimulus responsiveness. These systems show promise in cancer therapy, anti-infection, and tissue repair; however, challenges in biosafety, mechanistic understanding, and clinical translation remain, necessitating continued advances in material design and system integration.