Alternan exopolysaccharide as a novel precursor for hydrogel and cryogel wound dressings

The development of wound dressings that effectively manage exudate while providing antibacterial protection remains a key challenge. Cryogels offer advantages over conventional hydrogels due to their macroporous structure; however, while numerous biopolymer precursors have been employed in the synthesis of such materials, identifying sustainable and renewable alternatives remains of significant interest. In this context, alternan exopolysaccharide extracted from Limosilactobacillus reuteri E81 was cross-linked with epichlorohydrin to form hydrogels at 20 °C and cryogels at -20 °C. The cryogels exhibited a highly interconnected macroporous structure with an average pore size in the range of 84 ± 31 μm and a swelling equilibrium ratio qw of 14.01 ± 0.19. While cryogels reached equilibrium swelling in less than a minute due to their highly interconnected macroporous structure, mechanical testing demonstrated that cryogels possessed increased flexibility and withstood compressive stresses up to 12 MPa in the dry state. Vancomycin was subsequently loaded into the cryogels, and the resulting vancomycin-loaded cryogels effectively inhibited Staphylococcus aureus strains exhibiting different resistance profiles. Also, bioavailability and in vitro wound healing analyses demonstrated that vancomycin incorporation did not compromise cellular compatibility, while the vancomycin loaded cryogel samples exhibited higher cell viability at 24 h and enhanced fibroblast migration compared to unloaded samples, indicating a favorable cytocompatibility and wound closure profile. These findings underscore that alternan-based cryogels constitute a promising antibacterial wound-dressing platform, while also illustrating the broader potential of alternan as a novel and versatile biopolymer for gel fabrication and wound healing applications.