Investigating silver- and gold-functionalized electrospun PHBV fibers as dual-action antimicrobial and immunomodulatory biomaterials

Introduction – The growing prevalence of antibiotic-resistant bacteria highlights the urgent need for innovative antimicrobial materials. In this work, electrospun poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) fibers were functionalized with silver and gold nanoparticles (NPs) to combine high biocompatibility with strong antimicrobial activity. Methods – Silver and gold NPs were synthesized and characterized, confirming their anisotropic structure and high stability. Electrospinning produced uniform PHBV fibers, and surface modification with NPs via chitosan layer-by-layer ensured stable adhesion. Results – Antibacterial tests demonstrated that, among all, silver-containing samples exhibited complete inhibition of both Escherichia coli and Staphylococcus aureus, confirming the strong bactericidal effect of AgNPs. Chitosan alone partially inhibited S. aureus and didn't affect E. coli due to differences in bacterial cell wall architecture. While chitosan modestly contributed to antibacterial activity, adding AgNPs was crucial for broad, effective antimicrobial action. All functionalized fibers exhibited excellent cytocompatibility with human keratinocytes (HaCaT cells), maintaining over 70% metabolic activity. Moreover, cytokine profiling revealed an anti-inflammatory effect, most pronounced in AgNP-functionalized PHBV samples, and upregulation of human β-defensin 2 (HBD-2) in AuNP-functionalized samples, suggesting additional indirect antibacterial mechanisms. Discussion – The developed PHBV-based fibers functionalized with metallic NPs demonstrated an excellent balance of safety, cytocompatibility, and antibacterial performance, making them promising candidates for biomedical applications that require both inflammation control and antimicrobial protection.