Novel tragacanth gum-collagen-polyurethane hydrogels: Super-swelling, antibacterial, and fibrillogenesis-enhancing...

Tragacanth gum, a biodegradable polymer from Astragalus sap, offers a promising platform for advanced biomaterials due to its thickening, emulsifying, and stabilizing properties. This study synthesized novel tragacanth gum-collagen-polyurethane hydrogels with 20-60 wt% polysaccharide content. Semi-interpenetration of gum chains within the collagen-polyurethane matrix generated hybrid fibrillar-granular surfaces, with granular content increasing with gum concentration. Hydrogels with 40 wt% gum achieved 42 % collagen crosslinking, showing superabsorbent behavior with swelling capacities over 2600 %. Higher gum content improved viscoelastic stability, enhancing resistance to degradation at skin-relevant (pH 5.0) and physiological (pH 7.4) conditions while increasing susceptibility to alkaline (pH 8.5) and collagenase-rich environments. Granular regions efficiently encapsulated methylene blue, achieving 68 % release at skin pH and demonstrating antibacterial activity against E. coli (62 %) and S. aureus (50 %). The hydrogels exhibited excellent biocompatibility, promoting monocyte and fibroblast proliferation without hemolytic or cytotoxic effects. Notably, the 40 wt% gum hydrogel modulated immune responses by enhancing anti-inflammatory (TGF-β) release without increasing pro-inflammatory (CCL-2) cytokines. Additional features include self-healing capacity, fatigue resistance, and strong adhesiveness, highlighting the hydrogel's multifunctional potential for advanced wound healing applications.