Sustainable lignin-based composite hydrogels for controlled drug release and self-healing in antimicrobial wound dressing

Bacterial infections pose a significant threat to global public health, demanding innovative solutions in biomedical field. Lignin is a naturally abundant polyphenol-rich polymer, offer promising potential to fabricate advance biomaterials for biomedical applications. Hence, a composite hydrogel with antimicrobial and antioxidant activities based on the development of dynamic covalent bonds among sodium alginate, lignin and epigallocatechin-3-gallate (EGCG) was designed. Lignin provides structural integrity to hydrogel backbone as well as released synergistically with the drug. This synergistic effect of the pH-responsive controlled release of both EGCG and lignin improved the releasing ability and bioactivity of the hydrogels. In in vitro antimicrobial experiments, the addition of 3.08 wt% lignin significantly enhanced bactericidal efficacy against Escherichia coli and Staphylococcus aureus, raising the killing rate from 20 % to over 96 %. The dynamic borate bond allows hydrogel network to repair itself when it is disrupted. Its self-healing ability, pH-responsive drug delivery, biocompatibility and strong antimicrobial and antioxidant effects make it a promising candidate for chronic wound management. This lignin-based hydrogel marks a significant innovation in sustainable, multifunctional biomedical materials.