Development and functional characterization of alginate dressing as potential protein delivery system for wound healing

This study aimed to develop and characterize stable films as potential protein delivery dressings to wounds. Films were prepared from aqueous gels of sodium alginate (SA) and glycerol (GLY) (SA:GLY 1:0, 1:1, 1:2, 2:3, 2:1, 4:3). Purified recombinant glutathione-s-transferase (GST), green fluorescent protein (GFP) and GST fused in frame to GFP (GST-GFP) (model proteins) were characterized (SDS PAGE, Western blotting, immune-detection, and high sensitivity differential scanning calorimetry) and loaded (3.3, 6.6 and 30.2 mg/g of film) into SA:GLY 1:2 film. These were characterized using texture analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy, swelling, adhesion, dissolution and circular dichroism (CD). The protein loaded dressings were uniform, with a good balance between flexibility and toughness. The films showed ideal moisture content required for protein conformation (TGA), interactions between proteins and film components (DSC), indicating stability which was confirmed by CD. Swelling and adhesion showed that formulations containing 6.6 mg/g of protein possessed ideal characteristics and used for in vitro dissolution studies. Protein release was rapid initially and sustained over 72 h and data fitted to various kinetic equations showed release followed zero-order and Fickian diffusion. The results demonstrate the potential of SA dressings for delivering therapeutic proteins to wounds.