Engineered sodium alginate/poly (propylene glycol) phosphazene composite hydrogels: Toward functional remodeling of infected full-thickness skin defects.

In this study, a multifunctional composite hydrogel was developed by combining Sodium Alginate (Alg) with synthesized Poly(propylene glycol) phosphazene (PGP) for infected wound healing. Structural characterizations confirmed successful matrix formation, yielding a tunable macroporous network with excellent swelling capacity, high biosafety (hemolysis <5%), and prominent cell viability exceeding 100% in L929 fibroblasts. Erythromycin (Ery) was efficiently loaded (85.13%) and exhibited a sustained release profile over 96 h. Crucially, the Alg/PGP/Ery composite demonstrated strong synergistic antibacterial and bactericidal efficacy against both S. aureus and E. coli via a membrane-permeabilizing mechanism verified by FESEM. In vivo evaluations in a full-thickness infected rat model confirmed accelerated wound closure (75% y day 14) and marked clearance of the tissue bacterial burden. Furthermore, the hydrogel significantly suppressed local pro-inflammatory cytokine levels (TNF-α and IL-6) while upregulating angiogenic (VEGF) and extracellular matrix (Collagen I) gene expression. Histological examination corroborated superior tissue remodeling with complete re-epithelialization and the regeneration of cutaneous appendages including hair follicles and sebaceous glands. These findings demonstrate that the Alg/PGP/Ery hydrogel holds great promise as an advanced dressing for infected cutaneous wound repair.