Influences of Ag/Ag₂S core shell nanowires on the osteogenic differentiation of MC3T3-E1 cells and on the growth inhibition of methicillin-resistant Staphylococcus aureus

Owing to their antimicrobial properties, heavy metals have been identified as promising candidates to combat bacterial infections. Silver, which is a broad-spectrum biocide, is an effective alternative to other biocides but exhibits potential cytotoxicity. Here, we synthesized Ag/Ag₂S core shell nanowires by taking advantage of structurally well-defined silver nanowires and demonstrated them as promising agents for enhancing the osteogenic differentiation of MC3T3-E1 cells and for inhibiting the growth of methicillin-resistant Staphylococcus aureus (S. aureus). We examined structural, morphological, and chemical properties of the Ag/Ag₂S nanowires obtained from simple sulfidation of Ag nanowires using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, and transmission electron microscopy. The cytotoxicity of the nanowires was examined using an MTT assay employing MC3T3-E1 cells. The sulfide shell reduced the cytotoxic nature of Ag nanowires significantly exhibiting 99% viability of cells at a concentration of 6 µg/mL. Reactive oxygen species were measured via dihydroethidium staining and cell death was quantified through Annexin V-PI staining. Overall, Ag/Ag₂S core shell nanowires assist ROS induced differentiation of osteoblasts by regulating the key marker genes runx2, osterix, and osteocalcin. A bacterial live-dead cell assay was also performed to evaluate the impact of the nanowires on the growth of S. aureus. Significant disinfection against S. aureus was demonstrated at a minimal concentration of 4 µg/mL. Our current results suggest Ag/Ag₂S nanowires as an efficient scaffolding material in both osteogenesis promotion for cells and inhibition of bacterial growth.