Germanium-embedded bioactive fabric reduces bacterial bioburden and modulates fibroblast and macrophage behavior in...

Surgical site infections (SSIs) occur in 2%-4% of all surgical cases. Wearable bioactive fabrics (BAFs) containing semiconductor germanium are reported to promote microcirculation, enhance immunity, and increase antibacterial activity, with the potential to improve outcomes in SSIs. While BAFs are proposed to exert their effects through the generation of negative ions and the emission of far-infrared radiation, their mechanism of action has not been fully explored. The objective of this study was to evaluate the impact of BAFs on bacterial bioburden, fibroblast migration and proliferation, and inflammation modulation in the context of SSIs.

Utilizing an in vitro study design, BAF was compared to control fabric (CF; non-bioactive, without inclusion of semiconductors) and untreated (UT) groups using indirect assays in which the BAF was not in direct contact with cells or bacteria but was instead separated by an air gap. These assays examined the effects of BAF proximity on bacterial killing (Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922), fibroblast cell confluence, wound density, macrophage cytokine production, and macrophage differential gene expression.

BAF exposure reduced S. aureus bacterial bioburden compared to CF and UT (p < 0.0001) and reduced E. coli bioburden compared to UT (p < 0.0001). Wound density, indicating fibroblast migration was greater in the BAF group compared to CF and UT at 24 and 48 h (p = 0.03 and p < 0.01, respectively). Fibroblast proliferation was reduced in the BAF group compared to UT at 18 and 36 h (p = 0.04 and p = 0.01, respectively). Cytokines IL-10, IL-13, TNF-β, and PDGF were elevated in culture supernatants of macrophages treated with BAF compared with CF and UT (p < 0.05). IL-1β and IL-17A were elevated with BAF vs. CF treatment macrophages (p < 0.05), whereas IL-6 and IP-10 were elevated in BAF-treated macrophages compared with UT-treated macrophages (p < 0.05). BAFs also altered macrophage gene expression, including genes associated with interferon, innate immunity, and toll-like receptor pathways, compared with CF.

Exposure to BAFs exhibited direct and indirect bactericidal effects, enhanced fibroblast migration, reduced fibroblast proliferation, increased immunomodulatory cytokine secretion, and altered macrophage gene expression in ways that may positively impact wound healing. BAFs warrant further in vivo investigation to reduce SSIs and enhance healing.