Immunomodulatory and Microbiome Balancing Effects of Biocompatible Silver Nanostructures in Accelerating Skin Wound Healing

Chronic and infected cutaneous wounds represent a major clinical and socioeconomic burden, characterized by persistent inflammation, microbial imbalance, and impaired tissue regeneration. While silver based dressings are widely used for their broad spectrum antimicrobial activity, increasing evidence suggests that nanoscale silver structures can additionally modulate host immune responses and influence the wound microbiome. In this study, we engineered biocompatible silver nanostructures (AgNS) with optimized physicochemical properties (mean diameter ۱۸.۶ ± ۳.۴ nm; zeta potential −۲۱.۳ ± ۲.۱ mV) to minimize cytotoxicity while preserving multifunctional bioactivity. We systematically assessed: (i) antimicrobial efficacy against key wound pathogens (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli), (ii) immunomodulatory effects on macrophage polarization and cytokine production, (iii) in vivo wound closure, angiogenesis and collagen remodeling in a murine full thickness wound model, and (iv) wound microbiome dynamics via ۱۶S rRNA sequencing. AgNS exhibited potent antimicrobial activity (MIC: ۴–۱۲ μg/mL) and significantly attenuated lipopolysaccharide (LPS) induced pro inflammatory cytokines in macrophages (TNF α ↓۴۵.۷%, IL ۶ ↓۳۹.۸%, IL ۱β ↓۴۱.۲%), while enhancing IL ۱۰ secretion (↑۳۲.۵%), consistent with a shift toward an M۲ like phenotype. In vivo, AgNS accelerated wound closure by ۶۱.۴% at day ۱۰ compared with untreated controls (p < ۰.۰۰۱) and outperformed conventional antibiotic ointment. Histological and immunohistochemical analyses confirmed improved re epithelialization, denser and better organized collagen deposition, and enhanced angiogenesis (CD۳۱+ microvessel density ↑۴۷.۲%). Microbiome profiling revealed that AgNS not only reduced the relative abundance of pathogenic taxa such as S. aureus and P. aeruginosa (↓۶۳.۸%) but also partially restored microbial diversity (Shannon index: control ۱.۷۲ vs. AgNS ۲.۸۹), suggesting a microbiome balancing effect rather than indiscriminate sterilization. Collectively, our data indicate that rationally designed AgNS accelerate wound healing through a multifactorial mechanism that integrates antimicrobial activity, immune modulation, and microbiome re equilibration, offering a promising strategy for the management of chronic and infected skin wounds.

کلیدواژه ها:

silver nanostructures ، macrophage polarization ، antimicrobial nanomaterials ، skin regeneration