Injectable NIR-Responsive Lignin-Doped Polyaniline/Carvacrol-Integrated Gellan Gum Hydrogel for Photothermal-Assisted Antibacterial Therapy and Cell Migration

Hydrogels have gained considerable attention in wound management due to their biocompatibility and structural resemblance to the extracellular matrix. These properties help to maintain a moist wound environment, support cellular growth, and promote tissue regeneration. Moreover, multifunctional hydrogels that incorporate therapeutic and photothermal components have emerged as a promising approach to improving wound healing outcomes. In this study, we developed an injectable near-infrared (NIR)-responsive therapeutic hydrogel, denoted as GG@PC, based on gellan gum (GG) integrated with lignin-doped polyaniline (PANi) and carvacrol (CA) for photothermal-assisted antibacterial therapy and cell migration. The fabricated GG@PC hydrogel exhibited suitable rheological properties, injectability, and hemocompatibility. In vitro cytocompatibility analysis using L929 fibroblast cells confirmed the biocompatible nature of the developed hydrogel system, while the hydrogel also showed effective antioxidant activity. Under NIR laser irradiation, GG@PC exhibited efficient photothermal performance, with a photothermal conversion efficiency (PCE) of η = 40.9%, enabling localized thermal generation and maintaining stable performance during repeated heating-cooling cycles. NIR irradiation further enhanced the release of CA from the hydrogel matrix, demonstrating its photothermally responsive release behavior. Antibacterial studies against Escherichia coli and Staphylococcus aureus demonstrated effective antibacterial activity. Furthermore, the GG@PC-treated groups supported L929 fibroblast migration in the scratch assay. The GG@PC hydrogel integrates injectability, NIR-responsive photothermal performance, antioxidant and antibacterial activities, cytocompatibility, and enhanced cell migration within a single system, highlighting its potential as a multifunctional platform for photothermal-assisted antibacterial therapy and wound-care applications.