Wound-healing potential of curcumin loaded lignin nanoparticles

The emergence of new material platforms, focused on nanotechnology, have resulted in a growing interest in their application to healing skin wounds. The skin forms an effective barrier against the external environment and consequently, rapid healing of wound tissue after injury is essential. Curcumin (diferuloylmethane) is a promising small molecule for the treatment of wounds based on its wound-healing activity and antioxidant and anti-inflammatory properties. However, its therapeutic application is limited by the poor skin permeability and bioavailability due to its poor solubility and low stability. Herein, curcumin loaded LNPs was prepared and characterized for their wound healing activity. Cytotoxicity assays indicated that curcumin-free and loaded nanoparticles were biocompatible with skin keratinocytes with no cytotoxic effects, suggesting that they did not interfere with cell proliferation during wound healing. Curcumin loaded LNPs exhibited potent in vitro antibacterial activity against gram-positive bacterial pathogens, particularly against Staphylococcus aureus, the most common wound bacterium. Fibroblast cell migration was observed using a scratch assay; upon treatment with curcumin loaded LNPs, wounded keratinocytes exhibited increased cell migration, which is a key feature of wound healing. The in vivo results showed that wounded rats treated with curcumin loaded LNPs exhibited enhanced dermal wound closure compared with the untreated control. After 12 days, the wounds treated with curcumin loaded LNPs achieved nearly full wound contraction compared with the untreated control, which had a wound size reduction of approximately 43%. Curcumin-loaded LNPs treated wounds showed advanced granulation tissue formation, characterized by greater collagen deposition. They also had lower myeloperoxidase activity, which is indicative of less inflammatory infiltration. Lower expression of matrix metalloproteinases (MMPs), especially MMP9, was characteristic of wounds treated with curcumin loaded LNPs. Overall, the results from this study highlight the advantages of using lignin as a nanocarrier to accelerate wound healing.