Antimicrobial Cost-Effective Transparent Hydrogel Films from Renewable Gum Karaya/Chitosan Polysaccharides for Modern Wound Dressings

The newest trends in wound healing management and the development of the next generation of dressings are pointing toward natural polymeric materials with important beneficial properties such as antimicrobial effects, renewability, easier process of preparation, and biological activity. Here, we present the preparation and in vitro evaluation of a unique biopolymeric blend composed of natural polymers based on the positively charged polysaccharide chitosan and negatively charged gum karaya. A plate lysis assay of gum karaya and chitosan solution mixtures proved the synergistic antimicrobial effect against specific strains of both Gram-positive and Gram-negative bacteria and yeast. This polymeric mixture was used for hydrogel film preparation and determination of the composition effect on physical properties (swelling behavior in different solvents, pH, diffusion mechanism, hydrolytic stability, mechanical and optical properties). While the pure gum karaya with poly(vinyl alcohol) exhibited the highest hydrolytic degradation (68%), the mixture of poly(vinyl alcohol) and gum karaya with chitosan (in the 25:75 ratio) exhibited the lowest degradation value (41%) due to the strong physical interactions. Cytotoxicity tests performed with hydrogel extracts using two different in vitro models, adherent fibroblasts (NIH3T3) and non-adherent suspension B-lymphocytes (BaF3), exhibited excellent biocompatibility and no cytotoxicity. As expected, the antimicrobial activity of 3-day film extracts showed a significantly improved antimicrobial effect of mixtures involving a chitosan biopolymer. The physical and biological properties of prepared biopolymer-based hydrogels meet the requirements of modern wound dressings.