Electrocatalysis-Triggered Synergistic Chemo-Immunotherapy Enabled by an Implantable Conductive Hydrogel with a 3D Nanoelectrode Network

Electrocatalytic platinum nanomaterials are promising for tumor therapy, but their efficiency is constrained by the spatial limitations inherent in the traditional electrode/electrolyte three-phase interface mechanism. This study develops an injectable composite conductive hydrogel comprising sodium alginate, gelatin@polypyrrole, Pt nanowires, and Pt nanoparticles (SA/Gel@PPy/Pt NWs/Pt NPs) to overcome this issue. By synergizing the embedded Gel@PPy/Pt NWs with the Pt wire electrode, we create a 3D continuous electron circuit throughout the hydrogel. This overcomes the spatial limits of traditional interfaces, expanding the electrocatalytic chlorine evolution reaction from the 2D electrode surface into the 3D hydrogel volume, thus constructing a bulk-phase continuous electrode. This electrode integrates discrete catalytic sites via nanoscale electron pathways, rather than relying on the monolithic scaffold of traditional porous electrodes. The hydrogel leverages endogenous chloride ions to sustain electrocatalytic hypochlorous acid (HClO) generation, while its excellent tissue conformability enhances the therapeutic effect, enabling highly localized therapy. This potent oxidant (HClO) acts dually: it triggers proinflammatory antitumor immunity and dissolves the platinum components to release Pt ions, which synergistically induce DNA damage and enhance immunogenic cell death (ICD). Consequently, animal experiments demonstrated significant tumor suppression in a mouse model, establishing this 3D nanoelectrode network as a paradigm for efficient electrocatalytic tumor therapy.