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Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro

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ABSTRACT

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

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Quantitative assessment of cathepsin activity following Au-NP exposure. A fluorescent substrate was processed by cathepsin B (a) or cathepsin L (b) in Vero cells or purified cathepsin B (c) or L (d) treated with Au-NPs or left untreated. The fluorescence released following proteolytic cleavage of the substrate was determined using a fluorescent plate reader. The amount of cathepsin activity in the treatment groups is expressed as percent control and plotted as the mean +/- SEM. (*P < 0.05 significantly reduced, #P < 0.05 significantly increased; n = 6).
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Figure 6: Quantitative assessment of cathepsin activity following Au-NP exposure. A fluorescent substrate was processed by cathepsin B (a) or cathepsin L (b) in Vero cells or purified cathepsin B (c) or L (d) treated with Au-NPs or left untreated. The fluorescence released following proteolytic cleavage of the substrate was determined using a fluorescent plate reader. The amount of cathepsin activity in the treatment groups is expressed as percent control and plotted as the mean +/- SEM. (*P < 0.05 significantly reduced, #P < 0.05 significantly increased; n = 6).

Mentions: After a 24-h exposure of Vero cells to Au-NPs, a slight decrease in cathepsin B activity was observed in cells treated with either 10- or 30-nm Au-NPs at doses of 5–25 μg/ml (Figure 6a). A more significant decrease in cathepsin B activity was observed when the Vero cells were exposed to higher doses of these NPs (Figure 6a). Conversely, the low doses of 10- and 30-nm Au-NPs actually had a stimulatory effect on cathepsin L activity (Figure 6b). At concentrations of 1–10 μg/ml of the 10-nm particles and 5–50 μg/ml of the 30-nm particles, a significant upregulation of cathepsin L was observed in Vero cells (Figure 6b). A significant decrease in cathepsin L activity was finally observed at 50–100 μg/ml of the 10-nm Au-NP, but no decrease was ever seen in Vero cells treated with 30-nm Au-NPs (Figure 6b). Interestingly, incubation of the Au-NPs with the purified cathepsin enzymes had little impact on the enzymatic activity of either cathepsin B or L at 10 μg/ml (Figure 6c, d), and although there was a significant decrease in the 50 μg/ml dose of Au-NPs (Figure 6c, d), the decline in cathepsin activity with these NPs was not as dramatic as that observed with the Ag-NPs (Figure 4).


Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro
Quantitative assessment of cathepsin activity following Au-NP exposure. A fluorescent substrate was processed by cathepsin B (a) or cathepsin L (b) in Vero cells or purified cathepsin B (c) or L (d) treated with Au-NPs or left untreated. The fluorescence released following proteolytic cleavage of the substrate was determined using a fluorescent plate reader. The amount of cathepsin activity in the treatment groups is expressed as percent control and plotted as the mean +/- SEM. (*P < 0.05 significantly reduced, #P < 0.05 significantly increased; n = 6).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211222&req=5

Figure 6: Quantitative assessment of cathepsin activity following Au-NP exposure. A fluorescent substrate was processed by cathepsin B (a) or cathepsin L (b) in Vero cells or purified cathepsin B (c) or L (d) treated with Au-NPs or left untreated. The fluorescence released following proteolytic cleavage of the substrate was determined using a fluorescent plate reader. The amount of cathepsin activity in the treatment groups is expressed as percent control and plotted as the mean +/- SEM. (*P < 0.05 significantly reduced, #P < 0.05 significantly increased; n = 6).
Mentions: After a 24-h exposure of Vero cells to Au-NPs, a slight decrease in cathepsin B activity was observed in cells treated with either 10- or 30-nm Au-NPs at doses of 5–25 μg/ml (Figure 6a). A more significant decrease in cathepsin B activity was observed when the Vero cells were exposed to higher doses of these NPs (Figure 6a). Conversely, the low doses of 10- and 30-nm Au-NPs actually had a stimulatory effect on cathepsin L activity (Figure 6b). At concentrations of 1–10 μg/ml of the 10-nm particles and 5–50 μg/ml of the 30-nm particles, a significant upregulation of cathepsin L was observed in Vero cells (Figure 6b). A significant decrease in cathepsin L activity was finally observed at 50–100 μg/ml of the 10-nm Au-NP, but no decrease was ever seen in Vero cells treated with 30-nm Au-NPs (Figure 6b). Interestingly, incubation of the Au-NPs with the purified cathepsin enzymes had little impact on the enzymatic activity of either cathepsin B or L at 10 μg/ml (Figure 6c, d), and although there was a significant decrease in the 50 μg/ml dose of Au-NPs (Figure 6c, d), the decline in cathepsin activity with these NPs was not as dramatic as that observed with the Ag-NPs (Figure 4).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

No MeSH data available.


Related in: MedlinePlus