Studying antimicrobial activity of carbon nanotubes decorated with metal-doped ZnO hybrid materials

In this work, single wall nanotubes (SWNTs) and multi wall nanotubes (MWNTs) have been chemically treated with sulfuric acid and nitric acid (3:1 v/v). The Ag-doped ZnO and Au-doped ZnO nanoparticles have been decorated on SWNTs and MWNTs by the chemical precipitation method. The hybrid materials have been characterized via x-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectrophotometer, energy dispersive spectroscopy (EDS), and electron microscopy (FESEM, TEM). Antimicrobial activity of hybrid materials has been evaluated by using colony-forming unit assay and fluorescence microscope. Escherichia coli (E. coli) as Gram-negative and Staphylococcus aureus (S. aureus) as Gram-positive have been employed as the target bacterium. All hybrid materials have been reported to possess strong antimicrobial activity towards E. coli and S. aureus bacteria, due to synergistic effect between metal-doped ZnO nanoparticles and carbon nanotubes. A high bactericidal rates have been reported for all hybrid materials incubated in the dark and under UV light. The photocatalytic properties of metal-doped ZnO have been played important role for inhibiting bacterial growth due to generate reactive oxygen species (ROS) causing cellular toxicity.