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<p>The increased tendency of antibiotic resistance requires the development of alternative antibacterial materials, which should be effective. This consisted of the synthesis and the characterization of ZnO, Cu-doped ZnO (Cu/ZnO) and graphene oxide incorporated ZnO (GO/ZnO) nanomaterials using XRD, SEM, EDX and XPS to determine their structural, morphological and compositional characteristics. These findings were in line with the formation of hexagonal ZnO structure and effective incorporation of Cu and graphene oxide (GO), which led to the decrease of particle size, the enhancement of surface defects, and the surface area. The optical band gap values estimated from the UV–Visible absorption spectra were approximately 3.35&#xa0;eV for ZnO, 4.05&#xa0;eV for Cu/ZnO, and 4.08&#xa0;eV for GO/ZnO. SEM images indicate that pure ZnO consists of larger hexagonal particles (600&#xa0;nm), whereas Cu/ZnO (~ 95&#xa0;nm) and GO/ZnO (~ 45&#xa0;nm) exhibit much smaller, agglomerated nanostructures with higher surface area. The comparison of the antibacterial effect of 50–200&#xa0;µg/mL against Gram-positive (<i>Enterococcus faecium</i> and <i>Staphylococcus aureus</i>) and Gram-negative (<i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i>) bacteria was compared using the agar well diffusion technique. Cu/ZnO was most active with the largest inhibition zone value of 17.0 ± 0.9&#xa0;mm against <i>Escherichia coli</i> and 14.0 ± 0.7&#xa0;mm against <i>Pseudomonas aeruginosa</i> and GO/ZnO was the most active against Gram-positive bacteria with 14.5 ± 0.7&#xa0;mm against <i>Staphylococcus aureus</i>. Pure ZnO was not so active with all the strains. This is because of the increased defect sites, better surface area and increased generation of reactive oxygen species which leads to the improved antibacterial performance of Cu/ZnO and GO/ZnO. The novelty of this work is the direct comparison of Cu doping and GO incorporation as two distinct strategies for enhancing the antibacterial activity of ZnO. The study demonstrates that Cu/ZnO is more effective against Gram-negative bacteria, whereas GO/ZnO exhibits superior activity against Gram-positive bacteria, providing new insights into the development of targeted ZnO-based antibacterial materials.</p> Graphical abstract <p></p>

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Synergistic effects of copper doping and graphene oxide incorporation in ZnO nanomaterials for improved antibacterial activity

  • 期刊论文

  • 发表日期：

    2026年7月25日

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  • Thangavelan Niruban Balu,
  • Rajakumari Subramaniyan,
  • S. Sureshkumar

摘要

The increased tendency of antibiotic resistance requires the development of alternative antibacterial materials, which should be effective. This consisted of the synthesis and the characterization of ZnO, Cu-doped ZnO (Cu/ZnO) and graphene oxide incorporated ZnO (GO/ZnO) nanomaterials using XRD, SEM, EDX and XPS to determine their structural, morphological and compositional characteristics. These findings were in line with the formation of hexagonal ZnO structure and effective incorporation of Cu and graphene oxide (GO), which led to the decrease of particle size, the enhancement of surface defects, and the surface area. The optical band gap values estimated from the UV–Visible absorption spectra were approximately 3.35 eV for ZnO, 4.05 eV for Cu/ZnO, and 4.08 eV for GO/ZnO. SEM images indicate that pure ZnO consists of larger hexagonal particles (600 nm), whereas Cu/ZnO (~ 95 nm) and GO/ZnO (~ 45 nm) exhibit much smaller, agglomerated nanostructures with higher surface area. The comparison of the antibacterial effect of 50–200 µg/mL against Gram-positive (Enterococcus faecium and Staphylococcus aureus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria was compared using the agar well diffusion technique. Cu/ZnO was most active with the largest inhibition zone value of 17.0 ± 0.9 mm against Escherichia coli and 14.0 ± 0.7 mm against Pseudomonas aeruginosa and GO/ZnO was the most active against Gram-positive bacteria with 14.5 ± 0.7 mm against Staphylococcus aureus. Pure ZnO was not so active with all the strains. This is because of the increased defect sites, better surface area and increased generation of reactive oxygen species which leads to the improved antibacterial performance of Cu/ZnO and GO/ZnO. The novelty of this work is the direct comparison of Cu doping and GO incorporation as two distinct strategies for enhancing the antibacterial activity of ZnO. The study demonstrates that Cu/ZnO is more effective against Gram-negative bacteria, whereas GO/ZnO exhibits superior activity against Gram-positive bacteria, providing new insights into the development of targeted ZnO-based antibacterial materials.

Graphical abstract