An efficient antibacterial multi-scale web of carbon fibers with asymmetrically dispersed Ag–Cu bimetal nanoparticles

A multi-scale web of carbon micro-nanofibers was prepared for antibacterial applications by chemical vapor deposition (CVD) using silver (Ag) and copper (Cu) bimetal nanoparticles (Nps). Carbon nanofibers (CNFs) were grown on activated carbon fiber (ACF) substrate using acetylene as the carbon source. The CVD conditions were optimized such that Cu Nps catalyzed the CNF growth and were attached to the tips of the CNFs, whereas Ag Nps remained adhered to the ACF surface. The in vitro antimicrobial capability of the material was evaluated against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria. The bimetal-grown ACFs/CNFs completely inhibited the growth of bacteria for 7 days and performed superior to the ACFs/CNFs grown using Ag or Cu Nps alone. This way, more expensive Ag is partially replaced with less expensive Cu while maintaining a superior performance. The synergistic action of bimetal ions derived from the unique spatial segregation of Nps is likely owing to a greater opportunity for the Cu ions on the fiber tips to interact with bacteria.