Purpose: 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.

In the last 15 years, among the many reasons given for the development of idiopathic forms of Parkinson’s disease (PD), copper imbalance has been identified as a factor, and PD is often referred to as a copper-mediated disorder. More than 640 papers have been devoted to the relationship between PD and copper status in the blood, which include the following markers: total copper concentration, enzymatic ceruloplasmin (Cp) concentration, Cp protein level, and non-ceruloplasmin copper level. Most studies measure only one of these markers. Therefore, the existence of a correlation between copper status and the development of PD is still debated. Based on data from the published literature, meta-analysis, and our own research, it is clear that there is a connection between the development of PD symptoms and the number of copper atoms, which are weakly associated with the ceruloplasmin molecule. In this work, the link between the risk of developing PD and various inborn errors related to copper metabolism, leading to decreased levels of oxidase ceruloplasmin in the circulation and cerebrospinal fluid, is discussed.

Three main approaches are used to combat severe viral respiratory infections. The first is preemptive vaccination that blocks infection. Weakened or dead viral particles, as well as genetic constructs carrying viral proteins or information about them, are used as an antigen. However, the viral genome is very evolutionary labile and changes continuously. Second, chemical agents are used during infection and inhibit the function of a number of viral proteins. However, these drugs lose their effectiveness because the virus can rapidly acquire resistance to them. The third is the search for points in the host metabolism the effect on which would suppress the replication of the virus but would not have a significant effect on the metabolism of the host. Here, we consider the possibility of using the copper metabolic system as a target to reduce the severity of influenza infection. This is facilitated by the fact that, in mammals, copper status can be rapidly reduced by silver nanoparticles and restored after their cancellation.

We have previously shown that (1) an acute deficiency in blood serum holo-ceruloplasmin (Cp) developed in rats that were fed fodder containing silver ions (Ag-fodder) for one month and (2) the deficiency in holo-Cp was compensated by non-hepatic holo-Cp synthesis in rats that were chronically fed Ag-fodder for 6 months (Ag-rats). The purpose of the present study is to identify the organ(s) that compensate for the hepatic holo-Cp deficiency in the circulation. This study was performed on rats that were fed Ag-fodder (40 mg Ag·kg^-1 body mass daily) for 6 months. The relative expression levels of the genes responsible for copper status were measured by RT-PCR. The in vitro synthesis and secretion of [¹⁴C]Cp were analyzed using a metabolic labeling approach. Oxidase activity was determined using a gel assay with o-dianisidine. Copper status and some hematological indexes were measured. Differential centrifugation, immunoblotting, immunoelectrophoresis, and atomic absorption spectrometry were included in the investigation. In the Ag-rats, silver accumulation was tissue-specific. Skeletal muscles and internal (IAT) and subcutaneous (SAT) adipose tissues did not accumulate silver significantly. In SAT, the mRNAs for the soluble and glycosylphosphatidylinositol-anchored ceruloplasmin isoforms were expressed, and their relative levels were increased two-fold in the Ag-rats. In parallel, the levels of the genes responsible for Cp metallation (Ctr1 and Atp7a/b) increased correspondingly. In the SAT of the Ag-rats, Cp oxidase activity was observed in the Golgi complex and plasma membrane. Moreover, full-length [¹⁴C]Cp polypeptides were released into the medium by slices of SAT. The possibilities that SAT is part of a system that controls the copper balance in mammals, and it plays a significant role in supporting copper homeostasis throughout the body are discussed.

Silver nanoparticles (AgNPs) of various sizes and shapes are widely used because of their antibacterial properties. However, their bioactivity in mammals is insufficiently investigated. The aim of the present study was to assess the effect of AgNPs' shape on their antibacterial activity, cytotoxicity, and ability to interfere in copper metabolism in mice. For this, AgNPs with the same linear size (75 nm), but different shape (spherical and quasi-spherical), were fabricated by chemical reduction from silver nitrate. The test of the biological activity of AgNPs showed that both types of particles suppressed bacterial (E. coli) and mammalian (A549) cell growth in a time- and dose-dependent manner. Quasi-spherical AgNPs had stronger antibacterial activity (several orders of magnitude) than the spherical AgNPs. In mice, the intake, distribution and accumulation of silver from AgNPs depending on the administration method were compared and intraperitoneal injections were chosen as the most appropriate. Silver concentration in organs of mice and its distribution in the organs did not depend on the shape of AgNPs. During the 7 days of intraperitoneal treatment with AgNPs, the silver concentration in blood serum increased, while the copper concentration and ceruloplasmin (Cp) oxidase activity (measured by the o-dianisidine in-gel assay) decreased. At the same time, the Cp protein concentration determined by immunoblotting did not change. Analysis of the blood serum by gel-filtration has shown that blood serum silver was associated with Cp and with a larger protein, presumably α-2-macroglobulin. After the AgNP injections were cancelled, the organs and the blood serum were cleared from silver through bile, while the copper concentration and Cp oxidase activity of blood serum recovered to their normal levels. So, the correlation between particle shape and their biological activity was observed. Quasi-spherical AgNPs having more edges possessed higher antibacterial activity. At the same time, both types of AgNPs lowered the copper status of blood serum in mice in a similar manner. In the article, the potential danger of AgNP's low doses for mammals, including humans, and the specificity of the nanosilver turnover in the mammalian body, which suggests that AgNPs can be used for safe treatment, are discussed.