Size-Dependent Bioactivity of Silver Nanoparticles: Antibacterial Properties, Influence on Copper Status in Mice, and Whole-Body Turnover

Abstract

The ability of silver nanoparticles (AgNPs) of different sizes to influence copper metabolism in mice is assessed. Materials and Methods: AgNPs with diameters of 10, 20, and 75 nm were fabricated through a chemical reduction of silver nitrate and characterized by UV/Vis spectrometry, transmission and scanning electronic microscopy, and laser diffractometry. To test their bioactivity, Escherichia coli cells, cultured A549 cells, and C57Bl/6 mice were used. The antibacterial activity of AgNPs was determined by inhibition of colony-forming ability, and cytotoxicity was tested using the MTT test (viability, %). Ceruloplasmin (Cp, the major mammalian extracellular copper-containing protein) concentration and enzymatic activity were measured using gel-assay analyses and WB, respectively. In vitro binding of AgNPs with serum proteins was monitored with UV/Vis spectroscopy. Metal concentrations were measured using atomic absorption spectrometry. Results: The smallest AgNPs displayed the largest dose-and time-dependent antibacterial activity. All nanoparticles inhibited the metabolic activity of A549 cells in accordance with dose and time, but no correlation between cytotoxicity and nanoparticle size was found. Nanosilver was not uniformly distributed through the body of mice intraperitoneally treated with low AgNP concentrations. It was predominantly accumulated in liver. There, nanosilver was included in ceruloplasmin, and Ag-ceruloplasmin with low oxidase activity level was formed. Larger nanoparticles more effectively interfered with the copper metabolism of mice. Large AgNPs quickly induced a drop of blood serum oxidase activity to practically zero, but after cancellation of AgNP treatment, the activity was rapidly restored. A major fraction of the nanosilver was excreted in the bile with Cp. Nanosilver was bound by alpha-2-macroglobulin in vitro and in vivo, but silver did not substitute for the copper atoms of Cp in vitro. Conclusion:The data showed that even at low concentrations, AgNPs influence murine copper metabolism in size-dependent manner. This property negatively correlated with the antibacterial activity of AgNPs.

Counteraction of Biofilm Formation and Antimicrobial Potential of Terminalia catappa Functionalized Silver Nanoparticles against Candida albicans and Multidrug-Resistant Gram-Negative and Gram-Positive Bacteria

“…Overall, the zones of growth inhibition reflect the size dependent antimicrobial activity of TCE-Ag NPs against both bacterial as well as fungal strains. Our findings on the size and dose dependent antibacterial activity of TCE-Ag NPs are consistent with previously published research [ 53 , 54 ]. According to the recent work by [ 10 , 55 , 56 ], AgNPs synthesized by various methods have also antimicrobial action against Gram-negative and Gram-positive bacteria, as well as yeast, C. albicans .…”

Green Synthesis of Silver Nanoparticles Using the Flower Extract of Abelmoschus esculentus for Cytotoxicity and Antimicrobial Studies

“… 50 , 51 AgNPs trigger an increase in intracellular ROS, and reactive hydroxyl radicals damage DNA, which results in cell death. 52 AgNPs coated with plant bioconstitutents induce oxidative stress, leading to apoptosis via caspase-mediated and mitochondria-dependent pathways. 53 , 54 Nanoparticles induce hydroxyl radical formation and are highly toxic to cancer cells.…”

“…50,51 AgNPs trigger an increase in intracellular ROS, and reactive hydroxyl radicals damage DNA, which results in cell death. 52 AgNPs coated with plant bioconstitutents induce Figure 10 Morphological alterations in (A) TERT4 cell line and (B) A 549 cell lines exposed to AME-AgNPs at 1-100 mg/mL for 24 h. Images were taken using phase contrast inverted microscope at 20x magnification. oxidative stress, leading to apoptosis via caspase-mediated and mitochondria-dependent pathways.…”

Tannic Acid-Stabilized Silver Nanoparticles Used in Biomedical Application as an Effective Antimelioidosis and Prolonged Efflux Pump Inhibitor against Melioidosis Causative Pathogen

“…As far as size and shape are concerned, particles of a smaller size with good monodispersal of AgNPs seem to be more effective and have superior properties [18]. Many previous studies have indicated that the bactericidal properties of nanoparticles are size-dependent [7,[40][41][42]. The researchers have identified that AgNPs act primarily in three possible mechanisms against Gram-negative bacteria: (1) nanoparticles (mainly in the range of 1-10 nm) attach to the surface of the cell membrane, cause permeability and disrupt the respiration in bacteria; (2) AgNPs penetrate inside the bacterial cell and cause serious damage by interacting with sulfur-and phosphorus-containing macromolecules; (3) AgNPs release silver ions, which contribute to the bactericidal effect of the AgNPs [38,43].…”