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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.

No MeSH data available.


Cathepsin L confocal imaging in Ag-NP-treated Vero cells. A fluorescent substrate cleaved by active cathepsin L was detected using confocal microscopy in Vero cells treated with Ag-NPs or left untreated. a Negative control (Vero cells alone), b Positive control (Vero cells + CV-(FR)2), c 10-nm uncoated Ag-NP 10 μg/ml, d 10-nm uncoated Ag-NP 50 μg/ml, (e) 10-nm PS-Ag-NP 10 μg/ml, f 10-nm PS-Ag-NP 50 μg/ml, g 25-nm uncoated Ag-NP 10 μg/ml, h 25-nm uncoated Ag-NP 50 μg/ml, i 25-nm PS-Ag-NP 10 μg/ml, j 25-nm PS-Ag-NP 50 μg/ml. Red fluorescent intensity was normalized to Vero cells exposed to the substrate (b). The table below represents a quantitative assessment of the confocal images as determined using a fluorescent plate reader. The values indicate the mean percent of control +/- SEM (n = 6).
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Figure 3: Cathepsin L confocal imaging in Ag-NP-treated Vero cells. A fluorescent substrate cleaved by active cathepsin L was detected using confocal microscopy in Vero cells treated with Ag-NPs or left untreated. a Negative control (Vero cells alone), b Positive control (Vero cells + CV-(FR)2), c 10-nm uncoated Ag-NP 10 μg/ml, d 10-nm uncoated Ag-NP 50 μg/ml, (e) 10-nm PS-Ag-NP 10 μg/ml, f 10-nm PS-Ag-NP 50 μg/ml, g 25-nm uncoated Ag-NP 10 μg/ml, h 25-nm uncoated Ag-NP 50 μg/ml, i 25-nm PS-Ag-NP 10 μg/ml, j 25-nm PS-Ag-NP 50 μg/ml. Red fluorescent intensity was normalized to Vero cells exposed to the substrate (b). The table below represents a quantitative assessment of the confocal images as determined using a fluorescent plate reader. The values indicate the mean percent of control +/- SEM (n = 6).

Mentions: Cathepsin L activity appears to be more sensitive to Ag-NP exposure. All 4 types of Ag-NPs tested demonstrated a significant reduction of cathepsin L activity in Vero cells (Figure 3). Minimal cathepsin L activity was observed when the cells were treated with any of the Ag-NPs at 50 μg/ml (Figure 3d, f, h, j), and this decrease was determined by quantitative assessment to be statistically significant (Figure 3 table). There was little discernable difference in red fluorescence between the 10 μg/ml uncoated Ag-NP-treated cells (Figure 3c, g) versus the untreated control (Figure 3b), however, the PS-Ag-NPs (10 and 25 nm) appear to cause a slight, yet significant decline in cathepsin L activity at this dose (Figure 3e, i, table). The decrease in cathepsin L enzymatic activity caused by Ag-NPs was much greater than that observed with cathepsin B (Figures 2, 3).


Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro
Cathepsin L confocal imaging in Ag-NP-treated Vero cells. A fluorescent substrate cleaved by active cathepsin L was detected using confocal microscopy in Vero cells treated with Ag-NPs or left untreated. a Negative control (Vero cells alone), b Positive control (Vero cells + CV-(FR)2), c 10-nm uncoated Ag-NP 10 μg/ml, d 10-nm uncoated Ag-NP 50 μg/ml, (e) 10-nm PS-Ag-NP 10 μg/ml, f 10-nm PS-Ag-NP 50 μg/ml, g 25-nm uncoated Ag-NP 10 μg/ml, h 25-nm uncoated Ag-NP 50 μg/ml, i 25-nm PS-Ag-NP 10 μg/ml, j 25-nm PS-Ag-NP 50 μg/ml. Red fluorescent intensity was normalized to Vero cells exposed to the substrate (b). The table below represents a quantitative assessment of the confocal images as determined using a fluorescent plate reader. The values indicate the mean percent of control +/- SEM (n = 6).
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Related In: Results  -  Collection

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Figure 3: Cathepsin L confocal imaging in Ag-NP-treated Vero cells. A fluorescent substrate cleaved by active cathepsin L was detected using confocal microscopy in Vero cells treated with Ag-NPs or left untreated. a Negative control (Vero cells alone), b Positive control (Vero cells + CV-(FR)2), c 10-nm uncoated Ag-NP 10 μg/ml, d 10-nm uncoated Ag-NP 50 μg/ml, (e) 10-nm PS-Ag-NP 10 μg/ml, f 10-nm PS-Ag-NP 50 μg/ml, g 25-nm uncoated Ag-NP 10 μg/ml, h 25-nm uncoated Ag-NP 50 μg/ml, i 25-nm PS-Ag-NP 10 μg/ml, j 25-nm PS-Ag-NP 50 μg/ml. Red fluorescent intensity was normalized to Vero cells exposed to the substrate (b). The table below represents a quantitative assessment of the confocal images as determined using a fluorescent plate reader. The values indicate the mean percent of control +/- SEM (n = 6).
Mentions: Cathepsin L activity appears to be more sensitive to Ag-NP exposure. All 4 types of Ag-NPs tested demonstrated a significant reduction of cathepsin L activity in Vero cells (Figure 3). Minimal cathepsin L activity was observed when the cells were treated with any of the Ag-NPs at 50 μg/ml (Figure 3d, f, h, j), and this decrease was determined by quantitative assessment to be statistically significant (Figure 3 table). There was little discernable difference in red fluorescence between the 10 μg/ml uncoated Ag-NP-treated cells (Figure 3c, g) versus the untreated control (Figure 3b), however, the PS-Ag-NPs (10 and 25 nm) appear to cause a slight, yet significant decline in cathepsin L activity at this dose (Figure 3e, i, table). The decrease in cathepsin L enzymatic activity caused by Ag-NPs was much greater than that observed with cathepsin B (Figures 2, 3).

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.