Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

Abstract

Background

Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe₂O₃ nanoparticles against Gram-positive and Gram-negative bacteria.

Methods and results

Nanosized particles of three metal oxides (ZnO, CuO, and Fe₂O₃) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe₂O₃, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria.

Conclusion

Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe₂O₃ nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe₂O₃.

Keywords:

• nanomaterial
• ZnO
• CuO
• Fe₂O₃
• antibacterial activity
• metal oxides

Acknowledgments

Mr Arham S Ahmed and Mr M Oves are thankful to CSIR, New Delhi, for providing financial support in the form of SRF. Dr Adnan Memic would like to thank the Strategic Technologies Program of King Abdulaziz City for Science and Technology, grant number 10-NAN1081-3, for their partial support and funding of this project.

Disclosure

The authors report no conflicts of interest in this work.