Nanotechnology & Applications
Open Access10 nm Silver Nanoparticles Alter Neutrophil Function, Viability, and Adherence
Authors: Janice L Speshock, Ira S Floyd, Jordan Reeder, Jo Nell Prukop, Jeff A Brady.
Abstract
Neutrophils are circulating leukocytes found in the blood that migrate into tissues during inflammation. They are highly phagocytic, and due to the presence of cytotoxic granules, they are known to be very important microbicidal cells. Since it has been demonstrated that tissue-resident macrophages secrete pro-inflammatory cytokines following exposure to silver nanoparticles (AgNP), which activate the inflammatory response, we wanted to determine how the neutrophils would respond to the presence of AgNPs since they will likely migrate into exposed tissues. 10 nm PVP-coated AgNPs were incubated with primary neutrophils isolated from human blood, and it was noted using microscopy that at doses of AgNP greater than 10 micrograms per milliliter (μg/mL), the neutrophils were completely dead within an hour. Even a 1 hour incubation with 10 μg/mL resulted in a 20% reduction in neutrophil cell viability as determined with an MTS colormetric assay. Neutrophil activity was assessed at sub-toxic doses to determine the full extent at which these cells are being effected by AgNPs. At 1 and 10 μg/mL doses with 1 hour of exposure, a significant decrease in myeloperoxidase activity was observed, which suggests a defect in bactericidal activity of these cells. Microscopic observation demonstrates that the larger doses of AgNPs tend to form larger aggregates and these aggregates are likely taken up by these active phagocytes, which impacts gene expression and enzyme function. Since neutrophils are an essential cell in the clearance of microbial pathogens, it is important to assess whether the use of AgNPs as antimicrobial agents will impact the removal of infectious agents.
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