3D-printed multilayer GelMA-PVA dual-network hydrogels with gradient andrographolide loading for antimicrobial wound healing: Fabrication, characterization, and in vitro evaluation

Chronic wounds are often aggravated by bacterial infection and prolonged inflammation, presenting major challenges in clinical wound management. To address these issues, a novel 3D-printed multilayer hydrogel was developed, based on a GelMA-PVA dual-network system incorporating graded concentrations of andrographolide (Andro), a phytochemical with proven antibacterial and anti-inflammatory activity. The GelMA component was photocrosslinked, while the PVA network was physically crosslinked via freeze–thaw cycles, forming a robust interpenetrating structure. The hydrogels were characteriazed using FTIR, XPS, SEM, mechanical testing, swelling analysis, and in vitro release and antibacterial assays. The multilayer patches demonstrated tunable swelling capacity (up to 1938 %), excellent tensile strength (up to 46.7 kPa) and compressive strength (up to 94.3 kPa), and a sustained drug release profile. In vitro studies confirmed enhanced L929 fibroblast proliferation and significant antibacterial activity against E. coli and S. aureus , particularly in the gradient Andro-loaded groups. These results suggest that the 3D-printed GelMA-PVA-Andro patches are promising candidates for advanced wound dressings with integrated mechanical, biological, and pharmaceutical functionalities.