Injectable Conductive Hydrogel Patch with Spatiotemporally Tailored Asymmetric Adhesion for Myocardial Infarction Repair

Conventional cardiac patches face critical limitations, including invasive surgical trauma, nonspecific adhesion, and inadequate electromechanical integration, collectively limiting their therapeutic efficacy in myocardial infarction (MI) repair. Here, GRAXe is presented as an injectable hydrogel patch with asymmetric adhesion, biomimetic conductivity, and inflammation-modulating capabilities. The Janus structure of GRAXe is established through sequential crosslinking, involving Ca²⁺-induced pre-gelation (trigger A) followed by spatially directed UV fixation (trigger B) to form an asymmetric interpenetrating ionic-covalent network. This gelation paradigm enables spatial control over interfacial network assembly, yielding a myocardium-adherent interface via MXene-enhanced catechol coupling and an anti-adhesive surface through dense polymer entanglement, resulting in a 60-150-fold adhesion contrast. The conductive architecture of GRAXe (1.18 mS cm^-1) restores electrical synchrony across MI zones by re-establishing connexin-43-mediated intercellular coupling. Furthermore, the incorporation of reactive oxygen species-responsive thioketal networks enables on-demand suppression of lipid peroxidation and modulates macrophage polarization. In rat MI models, GRAXe restores electromechanical coupling, attenuates ventricular remodeling, and enhances cardiac functional recovery. This modular strategy integrates structural programmability with functional performance, offering a promising direction for minimally invasive cardiac repair.