pH-Controlled Cerium Oxide Nanoparticle Inhibition of Both Gram-Positive and Gram-Negative Bacteria Growth

• Published in: Scientific reports Vol. 7; no. 1; p. 45859
• Main Authors: Alpaslan, Ece, Geilich, Benjamin M., Yazici, Hilal, Webster, Thomas J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07-04-2017; Nature Publishing Group
• Subjects: 14/19; 631/61/350/354; 631/61/54; Antibacterial activity; Antibiotics; Bacteria; Cerium; Cerium - chemistry; Cerium - pharmacology; Dextran; Gram-negative bacteria; Humanities and Social Sciences; Hydrogen-Ion Concentration; multidisciplinary; Nanoparticles; Nanoparticles - chemistry; pH effects; Pseudomonas aeruginosa - drug effects; Pseudomonas aeruginosa - pathogenicity; Reactive oxygen species; Science; Staphylococcus epidermidis - drug effects; Staphylococcus epidermidis - pathogenicity; Surface charge
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep45859

Here, the antibacterial activity of dextran-coated nanoceria was examined against
Pseudomonas aeruginosa
and
Staphylococcus epidermidis
by varying the dose, the time of treatment, and the pH of the solution. Findings suggested that dextran-coated nanoceria particles were much more effective at killing
P. aeruginosa
and
S. epidermidis
at basic pH values (pH = 9) compared to acidic pH values (pH = 6) due to a smaller size and positive surface charge at pH 9. At pH 9, different particle concentrations did cause a delay in the growth of
P. aeruginosa
, whereas impressively
S. epidermidis
did not grow at all when treated with a 500 μg/mL nanoceria concentration for 24 hours. For both bacteria, a 2 log reduction and elevated amounts of reactive oxygen species (ROS) generation per colony were observed after 6 hours of treatment with nanoceria at pH 9 compared to untreated controls. After 6 hours of incubation with nanoceria at pH 9,
P. aeruginosa
showed drastic morphological changes as a result of cellular stress. In summary, this study provides significant evidence for the use of nanoceria (+4) for a wide range of anti-infection applications without resorting to the use of antibiotics, for which bacteria are developing a resistance towards anyway.