Functionalized Alginate-Glutathione (GSH) Hydrogels as Antioxidant Biomaterials for Skin Wound Repair

Abstract

Skin serves as the body’s primary barrier against pathogens, UV radiation, and mechanical damage. When blood flow is impaired or pressure is maintained, skin and underlying tissues can deteriorate, forming chronic wounds such as diabetic ulcers, pressure sores, and venous leg ulcers. These wounds remain trapped in a state of inflammation, where excess reactive oxygen species (ROS) and pro‑inflammatory molecules disrupt normal healing processes. Hydrogels are widely used as wound dressings and can be enhanced with antioxidant components to reduce oxidative stress and help resolve the inflammatory phase of wound healing. In this study, alginate, a natural and biocompatible hydrogel polymer, was functionalized with glutathione (GSH), a natural antioxidant peptide of the human body responsible for reducing oxidative stress through ROS scavenging, via carbodiimide chemistry (EDC/NHS). The resulting conjugate is intended for the development of antioxidant dressings for the treatment of chronic wounds. The conjugate synthesis parameters ((EDC:GSH) molar ratio, pH, and reaction time) were optimized to maximize peptide content of the conjugates and thiol group availability for redox activity compared to a conventional carbodiimide chemistry method. Results showed that the (EDC:GSH) molar ratio and pH positively influenced GSH grafting, but negatively impacted reduced thiol group proportions, while reaction time had no significant effect. Optimal synthesis conditions were identified as: (EDC:GSH) = (4:1), pH = 5.0, reaction time = 2 hours. Chemical characterization of the conjugates using 1H-NMR and quantitative analyses through BCA and Ellman assays demonstrated the successful conjugation of GSH to the alginate backbone through an amide linkage. The conjugates were able to scavenge 50% of H2O2 when dissolved in solution but seemed to have lost their scavenging capacity once crosslinked ionically into hydrogels. Nevertheless, alginate-GSH conjugates could show promise as an antioxidant dressing material to accelerate the healing of chronic skin wounds.