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Is the toxic potential of nanosilver dependent on its size?

Huk A, Izak-Nau E, Reidy B, Boyles M, Duschl A, Lynch I, Dušinska M - Part Fibre Toxicol (2014)

Bottom Line: However, re-calculation of Ag ENMs concentrations from mass unit to surface area and number of ENMs per cm2 highlighted that 200 nm Ag ENMs, are the most toxic.Strong cytotoxic and genotoxic effects were observed in cells exposed to Ag ENMs 50 nm, but Ag ENMs 200 nm had the most mutagenic potential.Additionally, we showed that expression of concentrations of ENMs in mass units is not representative.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Nanosilver is one of the most commonly used engineered nanomaterials (ENMs). In our study we focused on assessing the size-dependence of the toxicity of nanosilver (Ag ENMs), utilising materials of three sizes (50, 80 and 200 nm) synthesized by the same method, with the same chemical composition, charge and coating.

Methods: Uptake and localisation (by Transmission Electron Microscopy), cell proliferation (Relative growth activity) and cytotoxic effects (Plating efficiency), inflammatory response (induction of IL-8 and MCP-1 by Enzyme linked immune sorbent assay), DNA damage (strand breaks and oxidised DNA lesions by the Comet assay) were all assessed in human lung carcinoma epithelial cells (A549), and the mutagenic potential of ENMs (Mammalian hprt gene mutation test) was assessed in V79-4 cells as per the OECD protocol. Detailed physico-chemical characterization of the ENMs was performed in water and in biological media as a prerequisite to assessment of their impacts on cells. To study the relationship between the surface area of the ENMs and the number of ENMs with the biological response observed, Ag ENMs concentrations were recalculated from μg/cm2 to ENMs cm2/cm2 and ENMs/cm2.

Results: Studied Ag ENMs are cytotoxic and cytostatic, and induced strand breaks, DNA oxidation, inflammation and gene mutations. Results expressed in mass unit [μg/cm2] suggested that the toxicity of Ag ENMs is size dependent with 50 nm being most toxic. However, re-calculation of Ag ENMs concentrations from mass unit to surface area and number of ENMs per cm2 highlighted that 200 nm Ag ENMs, are the most toxic. Results from hprt gene mutation assay showed that Ag ENMs 200 nm are the most mutagenic irrespective of the concentration unit expressed.

Conclusion: We found that the toxicity of Ag ENMs is not always size dependent. Strong cytotoxic and genotoxic effects were observed in cells exposed to Ag ENMs 50 nm, but Ag ENMs 200 nm had the most mutagenic potential. Additionally, we showed that expression of concentrations of ENMs in mass units is not representative. Number of ENMs or surface area of ENMs (per cm2) seem more precise units with which to compare the toxicity of different ENMs.

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Related in: MedlinePlus

Induction of IL-8 and MCP-1 in A549 cells exposed to Ag ENMs 50, 80 and 200 nm. Cells were treated with 6 concentrations (μg/cm2) of Ag ENMs for 24 h. The data are expressed as mean ± SD of at least three independent experiments. *statistically significant (p < 0.05) difference from the unexposed control. Horizontal line represents expressed level of IL8 (81.8 ± 31.5 pg/ml) and MCP-1 (143.3 ± 26.68 pg/ml) in untreated cells. TNFα (20 ng/ml) as a positive control (IL-8) gave 386.5 ± 87.92 pg/ml and (MCP-1) gave 528.3 ± 134.52 pg/ml.
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Fig4: Induction of IL-8 and MCP-1 in A549 cells exposed to Ag ENMs 50, 80 and 200 nm. Cells were treated with 6 concentrations (μg/cm2) of Ag ENMs for 24 h. The data are expressed as mean ± SD of at least three independent experiments. *statistically significant (p < 0.05) difference from the unexposed control. Horizontal line represents expressed level of IL8 (81.8 ± 31.5 pg/ml) and MCP-1 (143.3 ± 26.68 pg/ml) in untreated cells. TNFα (20 ng/ml) as a positive control (IL-8) gave 386.5 ± 87.92 pg/ml and (MCP-1) gave 528.3 ± 134.52 pg/ml.

Mentions: The effect of 50, 80 and 200 nm Ag ENMs in the concentration range from 0.21-15.6 μg/cm2 on the cellular production of inflammatory cytokines (IL-8 and MCP-1) by A549 cells was measured using the ELISA assay (Figure 4). Reverse concentration response trends were observed for all tested materials. However, statistically significant differences were not found between any of the tested Ag ENMs when plotted in mass units.Figure 4


Is the toxic potential of nanosilver dependent on its size?

Huk A, Izak-Nau E, Reidy B, Boyles M, Duschl A, Lynch I, Dušinska M - Part Fibre Toxicol (2014)

Induction of IL-8 and MCP-1 in A549 cells exposed to Ag ENMs 50, 80 and 200 nm. Cells were treated with 6 concentrations (μg/cm2) of Ag ENMs for 24 h. The data are expressed as mean ± SD of at least three independent experiments. *statistically significant (p < 0.05) difference from the unexposed control. Horizontal line represents expressed level of IL8 (81.8 ± 31.5 pg/ml) and MCP-1 (143.3 ± 26.68 pg/ml) in untreated cells. TNFα (20 ng/ml) as a positive control (IL-8) gave 386.5 ± 87.92 pg/ml and (MCP-1) gave 528.3 ± 134.52 pg/ml.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4274708&req=5

Fig4: Induction of IL-8 and MCP-1 in A549 cells exposed to Ag ENMs 50, 80 and 200 nm. Cells were treated with 6 concentrations (μg/cm2) of Ag ENMs for 24 h. The data are expressed as mean ± SD of at least three independent experiments. *statistically significant (p < 0.05) difference from the unexposed control. Horizontal line represents expressed level of IL8 (81.8 ± 31.5 pg/ml) and MCP-1 (143.3 ± 26.68 pg/ml) in untreated cells. TNFα (20 ng/ml) as a positive control (IL-8) gave 386.5 ± 87.92 pg/ml and (MCP-1) gave 528.3 ± 134.52 pg/ml.
Mentions: The effect of 50, 80 and 200 nm Ag ENMs in the concentration range from 0.21-15.6 μg/cm2 on the cellular production of inflammatory cytokines (IL-8 and MCP-1) by A549 cells was measured using the ELISA assay (Figure 4). Reverse concentration response trends were observed for all tested materials. However, statistically significant differences were not found between any of the tested Ag ENMs when plotted in mass units.Figure 4

Bottom Line: However, re-calculation of Ag ENMs concentrations from mass unit to surface area and number of ENMs per cm2 highlighted that 200 nm Ag ENMs, are the most toxic.Strong cytotoxic and genotoxic effects were observed in cells exposed to Ag ENMs 50 nm, but Ag ENMs 200 nm had the most mutagenic potential.Additionally, we showed that expression of concentrations of ENMs in mass units is not representative.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Nanosilver is one of the most commonly used engineered nanomaterials (ENMs). In our study we focused on assessing the size-dependence of the toxicity of nanosilver (Ag ENMs), utilising materials of three sizes (50, 80 and 200 nm) synthesized by the same method, with the same chemical composition, charge and coating.

Methods: Uptake and localisation (by Transmission Electron Microscopy), cell proliferation (Relative growth activity) and cytotoxic effects (Plating efficiency), inflammatory response (induction of IL-8 and MCP-1 by Enzyme linked immune sorbent assay), DNA damage (strand breaks and oxidised DNA lesions by the Comet assay) were all assessed in human lung carcinoma epithelial cells (A549), and the mutagenic potential of ENMs (Mammalian hprt gene mutation test) was assessed in V79-4 cells as per the OECD protocol. Detailed physico-chemical characterization of the ENMs was performed in water and in biological media as a prerequisite to assessment of their impacts on cells. To study the relationship between the surface area of the ENMs and the number of ENMs with the biological response observed, Ag ENMs concentrations were recalculated from μg/cm2 to ENMs cm2/cm2 and ENMs/cm2.

Results: Studied Ag ENMs are cytotoxic and cytostatic, and induced strand breaks, DNA oxidation, inflammation and gene mutations. Results expressed in mass unit [μg/cm2] suggested that the toxicity of Ag ENMs is size dependent with 50 nm being most toxic. However, re-calculation of Ag ENMs concentrations from mass unit to surface area and number of ENMs per cm2 highlighted that 200 nm Ag ENMs, are the most toxic. Results from hprt gene mutation assay showed that Ag ENMs 200 nm are the most mutagenic irrespective of the concentration unit expressed.

Conclusion: We found that the toxicity of Ag ENMs is not always size dependent. Strong cytotoxic and genotoxic effects were observed in cells exposed to Ag ENMs 50 nm, but Ag ENMs 200 nm had the most mutagenic potential. Additionally, we showed that expression of concentrations of ENMs in mass units is not representative. Number of ENMs or surface area of ENMs (per cm2) seem more precise units with which to compare the toxicity of different ENMs.

Show MeSH
Related in: MedlinePlus