A lignin-based biocomposite hydrogel for antimicrobial and wound healing applications†

Skin, the body's largest organ, plays a key role in protection, sensory perception, temperature regulation, and immune defense. Any damage to this protection makes the skin susceptible to infections and though the body heals itself, wound healing, however, is often challenged by various factors. Current wound dressing options encompass hydrogels, films, wafers, nanofibers, foams, topicals, patches, sponges, and bandages. Among these, hydrogels offer unique advantages such as creating a conducive moist environment, high moisture retention, and a barrier against bacterial intrusion, making them ideal for managing exudative and granulating wounds. Biopolymers are being preferred over synthetic polymers for the development of hydrogels owing to their non-toxic, biodegradable, and biocompatible properties. In this study, hydrogels were synthesized successfully using lignin and chitosan as biopolymers, chondroitin sulphate as a cross-linker, and poly-vinyl alcohol as an emulsifier, respectively. The hydrogels were loaded with oxytetracycline (OTC), a broad-spectrum antibiotic, in varying doses to provide antibacterial efficacy for wound management, recognizing wounds' susceptibility to infections. The hydrogels were characterized by FTIR, DSC, and scanning electron microscopy, revealing smooth surfaces. OTC release followed a time-dependent pattern, with 25% and 13% drug released at pH 7.4 and 4, respectively. The hydrogels were found to be non-hemolytic and exhibited non-cytotoxic properties towards mouse fibroblast cells. Fibroblast cell migration rates and antibacterial activity against Gram-negative (E. coli) and Gram-positive bacteria (S. aureus) highlighted the hydrogels' potential for wound healing and bacterial protection. These findings suggest that biopolymer-based, drug-loaded hydrogels hold promise for advancing wound care treatments.