Electrospun silk fibroin nanofibers enriched with metallic nanoparticles and phenolic acids for antimicrobial applications

Current trends in the development of the next generation of advanced wound dressings are directed toward the use of natural polymeric materials with additional properties such as antimicrobial function, controlled permeability, renewability, easy preparation, wound conformability and biocompatibility. Herein, fibrous hybrid organic-inorganic membranes of silk fibroin (SF) were prepared by electrospinning and were enriched with metal nanoparticles (Ag and Cu NPs) and phenolic compounds: caffeic, rosmarinic, and ellagic acids (CA, RA, EA, respectively) by using inert gas condensation sputtering and spin-coating, respectively. Various experimental techniques were involved in the precise characterization of the resulting mats: SEM/TEM, EDX, ATR-IR, AFM, XPS, goniometry, ICP-MS, direct and indirect antibacterial and cytotoxic assays in vitro. The optimized electrospinning and further surface functionalization allow for obtaining inorganic-organic hybrid nanofibrous mats with a defined structural homogeneity, antibacterial activity, and cytocompatibility. Of all the tested electrospun mats, those containing Ag NPs and ellagic acid (SF_Ag NPs_EA) were selected for further analysis, as they combine antibacterial activity and reduced cytotoxicity in vitro. The major role of the selected phenolic acid in the observed biological activity, together with a reduced cytotoxic effect of the released Ag ions from the corresponding loaded NPs were responsible for the antibacterial activity observed, while ensuring cytocompatibility against eukaryotic cells. Hence, these advanced electrospun mats are promising candidates as antimicrobial biosafe biomaterials and provide fundamental information for future industrial applications.