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

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ABSTRACT

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.

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Bacterial growth inhibition and growth rate (μ) and lag phase (λ) comparison.Proliferation of 106 CFU/mL of Gram-negative bacteria P. aeruginosa (a,b) and Gram-positive bacteria S. epidermidis (c,d) was measured over 24 hours in the presence of different concentrations of cerium oxide nanoparticles at pH 6 (a and c) and at pH 9 (b and d). Values represent the mean +/−SEM, N = 3. Corresponding Gompertz Model curve fitting parameters of each bacteria in every condition was calculated. Values represent the mean +/−SEM, N = 3 and *p < 0.05 compared to the untreated control.
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f3: Bacterial growth inhibition and growth rate (μ) and lag phase (λ) comparison.Proliferation of 106 CFU/mL of Gram-negative bacteria P. aeruginosa (a,b) and Gram-positive bacteria S. epidermidis (c,d) was measured over 24 hours in the presence of different concentrations of cerium oxide nanoparticles at pH 6 (a and c) and at pH 9 (b and d). Values represent the mean +/−SEM, N = 3. Corresponding Gompertz Model curve fitting parameters of each bacteria in every condition was calculated. Values represent the mean +/−SEM, N = 3 and *p < 0.05 compared to the untreated control.

Mentions: At an acidic environment (pH 6), P. aeruginosa growth was not affected by nanoceria at 250 μg/mL (Fig. 3a). A 2 hour delay in lag time (λ) was seen in the 500 μg/mL treated samples. No significant change was observed in the calculated growth rate (μ) for both concentrations. All treatments were compared to an untreated control grown in pH 6 conditions.


pH-Controlled Cerium Oxide Nanoparticle Inhibition of Both Gram-Positive and Gram-Negative Bacteria Growth
Bacterial growth inhibition and growth rate (μ) and lag phase (λ) comparison.Proliferation of 106 CFU/mL of Gram-negative bacteria P. aeruginosa (a,b) and Gram-positive bacteria S. epidermidis (c,d) was measured over 24 hours in the presence of different concentrations of cerium oxide nanoparticles at pH 6 (a and c) and at pH 9 (b and d). Values represent the mean +/−SEM, N = 3. Corresponding Gompertz Model curve fitting parameters of each bacteria in every condition was calculated. Values represent the mean +/−SEM, N = 3 and *p < 0.05 compared to the untreated control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384081&req=5

f3: Bacterial growth inhibition and growth rate (μ) and lag phase (λ) comparison.Proliferation of 106 CFU/mL of Gram-negative bacteria P. aeruginosa (a,b) and Gram-positive bacteria S. epidermidis (c,d) was measured over 24 hours in the presence of different concentrations of cerium oxide nanoparticles at pH 6 (a and c) and at pH 9 (b and d). Values represent the mean +/−SEM, N = 3. Corresponding Gompertz Model curve fitting parameters of each bacteria in every condition was calculated. Values represent the mean +/−SEM, N = 3 and *p < 0.05 compared to the untreated control.
Mentions: At an acidic environment (pH 6), P. aeruginosa growth was not affected by nanoceria at 250 μg/mL (Fig. 3a). A 2 hour delay in lag time (λ) was seen in the 500 μg/mL treated samples. No significant change was observed in the calculated growth rate (μ) for both concentrations. All treatments were compared to an untreated control grown in pH 6 conditions.

View Article: PubMed Central - PubMed

ABSTRACT

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&thinsp;=&thinsp;9) compared to acidic pH values (pH&thinsp;=&thinsp;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&thinsp;&mu;g/mL nanoceria concentration for 24&thinsp;hours. For both bacteria, a 2&thinsp;log reduction and elevated amounts of reactive oxygen species (ROS) generation per colony were observed after 6&thinsp;hours of treatment with nanoceria at pH 9 compared to untreated controls. After 6&thinsp;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.

No MeSH data available.


Related in: MedlinePlus