Contractile hydrogel with NIR-induced spatiotemporally programmed release from core-shell nanoparticles for integrated antibacterial and pro-angiogenic healing.

Bacterial colonization, biofilm formation, and microenvironmental dysregulation collectively impede the healing of infected wounds, highlighting the necessity for multifunctional intelligent dressings capable of promoting wound contraction while simultaneously providing antibacterial and regenerative functions. Therefore, this study reported the fabrication of a contractile MPLG hydrogel via the copolymerization of GelMA, NIPAM, and NAGA with Mg@PDA-Lev. Nanoparticle synthesis was performed through Mg2+-assisted dopamine polymerization followed by levofloxacin conjugation. The developed platform employs a synergistic therapeutic mechanism in which the acidic wound environment triggers pH-responsive degradation of PDA and subsequent levofloxacin release, while NIR irradiation activates the PDA coating to generate photothermal heat capable of disrupting the bacterial membranes. Furthermore, sustained Mg2+ release simultaneously facilitated M2 macrophage polarization and stimulated fibroblast activity along with extracellular matrix (ECM) remodeling. The thermoresponsive properties of PNIPAM and PNAGA enable the hydrogel to undergo controllable self-contraction upon NIR irradiation while facilitating on-demand drug release. In vitro assays demonstrated the potent broad-spectrum antibacterial activity of MPLG hydrogel against both Gram-positive and Gram-negative pathogens, significantly disrupting biofilms with negligible cytotoxicity. The developed hydrogel integrates synergistic antibacterial, antioxidant, angiogenic, and immunomodulatory effects to restore the wound microenvironment and accelerate healing, representing a promising therapeutic platform for the treatment of infected wounds.