Next Article in Journal
Lysozyme Associated Liposomal Gentamicin Inhibits Bacterial Biofilm
Next Article in Special Issue
Azithromycin and Chloramphenicol Diminish Neutrophil Extracellular Traps (NETs) Release
Previous Article in Journal
Endoplasmic Reticulum Stress and Homeostasis in Reproductive Physiology and Pathology
Previous Article in Special Issue
Interaction of New-Developed TiO2-Based Photocatalytic Nanoparticles with Pathogenic Microorganisms and Human Dermal and Pulmonary Fibroblasts
Article Menu
Issue 4 (April) cover image

Export Article

Open AccessArticle
Int. J. Mol. Sci. 2017, 18(4), 793;

pH-Dependent Antimicrobial Properties of Copper Oxide Nanoparticles in Staphylococcus aureus

Graduate School of Biotechnology and Bioengineering, Yuan Ze University, Taoyuan 320, Taiwan
Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 320, Taiwan
Author to whom correspondence should be addressed.
Academic Editors: Alexandru Mihai Grumezescu and Alina Maria Holban
Received: 6 March 2017 / Revised: 30 March 2017 / Accepted: 3 April 2017 / Published: 8 April 2017
Full-Text   |   PDF [3616 KB, uploaded 8 April 2017]   |  


The antimicrobial properties of CuO nanoparticles have been investigated, but the underlying mechanisms of toxicity remain the subject of debate. Here, we show that CuO nanoparticles exhibit significant toxicity at pH 5 against four different Staphylococcus aureus (S. aureus) strains, including Newman, SA113, USA300, and ATCC6538. At this pH, but not at pH 6 and 7, 5 mM CuO nanoparticles effectively caused reduction of SA113 and Newman cells and caused at least 2 log reduction, whereas 20 mM killed most strains but not USA300. At 5 mM, the nanoparticles were also found to dramatically decrease reductase activity in SA113, Newman, and ATCC6538 cells, but not USA300 cells. In addition, analysis of X-ray absorption near-edge structure and extended X-ray absorption fine structure confirmed that S. aureus cells exposed to CuO nanoparticles contain CuO, indicating that Cu2+ ions released from nanoparticles penetrate bacterial cells and are subsequently oxidized intracellularly to CuO at mildly acidic pH. The CuO nanoparticles were more soluble at pH 5 than at pH 6 and 7. Taken together, the data conclusively show that the toxicity of CuO nanoparticles in mildly acidic pH is caused by Cu2+ release, and that USA300 is more resistant to CuO nanoparticles (NPs) than the other three strains. View Full-Text
Keywords: copper oxide nanoparticles; Staphylococcus aureus; XANES; EXAFS copper oxide nanoparticles; Staphylococcus aureus; XANES; EXAFS

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Supplementary material


Share & Cite This Article

MDPI and ACS Style

Hsueh, Y.-H.; Tsai, P.-H.; Lin, K.-S. pH-Dependent Antimicrobial Properties of Copper Oxide Nanoparticles in Staphylococcus aureus. Int. J. Mol. Sci. 2017, 18, 793.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Int. J. Mol. Sci. EISSN 1422-0067 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top