Antimicrobial behavior comparison and antimicrobial mechanism of silver coated carbon nanocomposites

• Three carbon-Ag nano-composites are prepared using same chemical synthesis method.
• The carbon-Ag nanomaterials disinfection activities toward E. coli and S. aureus are compared.
• GO-Ag disinfection performance is the best.
• SEM images illustrate that GO-Ag nanoparticles cause morphological changes in cells.
• GO-Ag induces O2− oxidative stress on bacterial cells.

Nanomaterials have been intensively used as antibacterial agents, due to their efficient disinfection without harmful disinfection byproducts. Silver nanoparticles have attracted considerable attention. However, silver nanoparticles are likely to aggregate. In this work, we used a simple and facile one-step approach for the preparation of carbon nanotubes-silver (including single-walled carbon nanotubes-silver (SWCNTs-Ag) and multi-walled carbon nanotubes-silver (MWCNTs-Ag)) and graphene oxide-silver (GO-Ag) nanoparticles. The synthesized carbon-silver nanocomposites were characterized by XPS, TEM, EDS and Zeta-sizer. We compared the disinfection activity of six materials (i.e. GO, SWCNTs, MWCNTs, GO-Ag, SWCNTs-Ag and MWCNTs-Ag) toward two strains including Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Under similar concentration and incubation conditions, GO-Ag showed the highest disinfection activity. Antioxidant enzyme activities and lipid peroxidation assays induced by GO-Ag proved that GO-Ag was capable of inducing O2.− oxidative stress on bacterial. Subsequently affected the cell membrane integrity and thus resulted in cell death. GO-Ag with excellent disinfection efficiency against E. coli and S. aureus highlighted the potential application of GO-Ag in water disinfection.

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