Polydopamine-functionalized silk-based biomaterial for non-antibiotic antimicrobial therapy

Silk fibroin is a highly promising biomaterial for wound dressings; however, its lack of inherent antibacterial activity limits broader clinical adoption. In this study, robust antibacterial properties were successfully conferred onto electrospun silk fibroin nanofiber mats using a mussel-inspired polydopamine (PDA) dip-coating strategy. Primary dip-coating deposited a uniform PDA nanolayer that served as an adhesive scaffold, enabling subsequent anchoring of dopamine nanoparticles during secondary coating. This hierarchical structure markedly increased surface roughness and reactive catechol density. Antibacterial evaluation against Staphylococcus aureus showed that secondary PDA-coated mats substantially reduced bacterial colonization relative to both primary-coated and unmodified controls. Secondary coating cycles further enhanced antibacterial performance. Cytocompatibility assessment performed according to ISO 10993-5 confirmed excellent biocompatibility of the modified mats, with no significant cytotoxicity observed. This simple, versatile, and antibiotic-free functionalization approach significantly improves the translational potential of silk fibroin nanofibers as next-generation antibacterial wound dressings.