Evaluation of copper(I)-doped zinc oxide composite nanoparticles on both gram-negative and gram-positive bacteria

Antibiotic resistance is a serious problem all over the world. Inorganic metal oxide nanoparticles are suitable substitutional treatments for organic antibiotic-resistant bacterial infections. Various copper dopped ZnO nanocomposites were prepared with chemical deposition method in aqueous solution. X-ray diffraction (XRD) coupled with energy dispersive spectroscopy results reveals that cuprous oxide is uniformly doped on the surface of ZnO nanoparticles , forming Cu 2 O/ZnO nanocomposites. In addition, from Transmission electron microscopy (TEM) and scanning electron microscopy analysis , the average size of prepared Cu 2 O/ZnO composite is about 30 nm. The antibacterial activity of the Cu 2 O/ZnO composite was examined on two bacteria strains: Gram-positive Staphylococcus aureus ( S. aureus ) and Gram-negative Escherichia coli ( E. coli ). When the doping amount of Cu 2 O reaches more than 5%, a 3.58 log-reduction of S. aureus growth under visible light within 30 mins treatment was observed. The antibacterial activity of Cu 2 O/ZnO is 2.7-fold higher than pure ZnO and killing bacteria on E. coli with a 1.0 log-reduction in viability. Meanwhile, the bacteriological properties of Cu doped ZnO composites with different valence states (Cu 2+ , CuO, Cu 2 O, and Cu 0 ) were compared. Furthermore, the antibacterial mechanism was further discussed in this paper.