Adhesive Gelatin/Chitosan Hydrogel Coating Containing MgO Nanoparticles for Promoting Soft Tissue Integration

The implant-soft tissue interface is critical for successful integration. However, developing multifunctional coatings that combine antibacterial action, strong interfacial adhesion, and regenerative capacity remains a significant challenge. This study presents a novel hydrogel coating for surface modification of phthalazinone-naphthalene-based Poly(phthalazinone ether ketone) (PPEK) implants. The coating consists of an MgO nanoparticle-embedded, photocrosslinked gelatin/chitosan hydrogel functionalized with NHS groups. XPS and ¹H NMR analyses confirmed that NHS groups mediate covalent bonding. This bonding occurs with amine moieties on both plasma-activated PPEK implants and soft tissues, substantially improving interfacial adhesion. The coating demonstrated dual functionality: broad-spectrum antibacterial activity and sustained Mg²⁺ release. The released Mg²⁺ exhibited multiphase bioeffects. These bioeffects include enhanced migration of L929 fibroblasts, HUVECs, and HaCaT keratinocytes; stimulated HUVEC tubulogenesis; and upregulated extracellular matrix synthesis. Both in vitro and in vivo assessments revealed synergistic acceleration of collagen deposition and angiogenesis. This synergy facilitates rapid soft tissue regeneration. Subcutaneous implantation models demonstrated dual integration mechanisms: NHS-driven covalent adhesion and Mg²⁺-mediated bioactive remodeling via cellular activation. These results position the MgO-integrated nanocomposite hydrogel as a multifunctional therapeutic coating. It simultaneously addresses microbial resistance, interfacial stability, and tissue regeneration for optimized implant-soft tissue integration. The design paradigm merges physicochemical bonding with ion-modulated bioactivity. This approach offers a strategic solution for complex interface engineering in biomedical implants.