Accumulation of silver from drinking water into cerebellum and musculus soleus in mice

Transport pathway of the Ag+ following artificial precipitation enhancement activities

Artificial precipitation enhancement (APE) activities have been applied extensively around the world to enhance water resources. However, the transport way of the silver iodide catalyst utilized remains completely unknown. To address this issue, in this study, we monitored the content of silver ions (Ag+) in a water body under the influence of APE for a period of 16 years (2004-2019). Additionally, we monitored the content of silver ions in the multi-period rainfall and soil. Our findings indicate that after the APE operation, the detected silver content in the precipitation initially demonstrated an upward trend and then decreased to 0. Furthermore, we observed that some of the silver ions remained in the air for a period extending from the time of artificial rain till the next rain. The silver ion content in the soil during the flood season was elevated by 44 % in comparison to the non-operation period; the concentration of silver ions in the water body during the operation period was 42.86 % higher than that in the non-operation period. During the long-term study, spanning 16 years, the water body played a leading role in regulating the content of silver ions released by the APE, resulting in an increase in silver ion content by 3.3 %. Our results revealed the presence of silver in the precipitation after the APE operation, indicating that silver iodide initially entered the precipitation after catalysis. Furthermore, upon the comparison of the soil and surface water during the operation period and non-operation period, the silver content during the operation period was observed to be higher than that in the non-operation period, indicating that silver iodide was incorporated into the underlying surface from the precipitation. Therefore, we have concluded that the transport pathway of silver involves its initial entry into precipitation after sowing, subsequently descending with the precipitation to reach the soil and surface water. The findings of this study establish a scale ruler for the impact of increasing global APE activities on the environment, as well as first-hand data for preventing possible future environmental risks.

Tissue Distribution, Pharmacokinetics, and Effect of Hematological and Biochemical Parameters of Acute Intravenous Administration of Silver Nanoparticles in Rats

The widespread biomedical and commercial applications of silver nanoparticles (AgNPs) have increased their potential for human and environmental exposure and toxicity to human health. The bio-distribution and toxicity of AgNPs in rodents following inhalation, intratracheal instillation, and oral ingestion are well documented; however, little is known about the bio-distribution of intravenously (IV)-administered AgNPs and their organ-specific pathophysiological effects. Here, we investigate the pharmacokinetic pattern and tissue distribution of AgNPs in male rats following IV administration. The animals were humanely sacrificed after 10 min, 1 h, 6 h, 12 h, 24 h, and 168 h of AgNP administration, and the silver (Ag) content was measured from blood samples and various tissues following acid digestion. The AgNPs were readily absorbed and subsequently distributed into most organs predominantly in the colon, small intestine, kidney, and heart after 6 h; however, they were the highest in the spinal cord after 168 h. White blood cells (WBCs) were significantly increased (42-60%) in AgNP-administered animals at all time points except 10 min. Regarding platelets, all AgNP-administered animals showed counts 7.8-39.2% lower, with the lowest count at 168 h post-administration. In the case of lymphocytes (LYMs), the AgNP-treated animals exhibited a count 19.5-41% lower at 10 min and 1 h post-administration; however, the animals at 168 h post-administration showed a count 30.5% more. The mean corpuscular hemoglobin (MCH) counts from the AgNP-treated animals were decreased by 50-62%. The concentrations of aspartate transaminase (AST), urea, and creatinine were increased in the AgNP-treated animals. Taken together, the results suggest that the acute IV administration of AgNPs alters metabolic and hematological parameters in animals and may pose a health risk to humans.

Development and analysis of a universal label-free micro/nano component for three-channel detection of silver ions, mercury ions, and tetracycline

In this paper, an enzyme-free and label-free fluorescent nanomodule is proposed for rapid, simple and sensitive detection of Ag+, Hg2+ and tetracycline (TC). The strategy is cleverly designed to enable multiple-purpose detection with as little as 31 nt of ssDNA. Both the embedded dye SYBR Green I and the nanomaterial graphene oxide (GO) are able to distinguish single-stranded DNA from double-stranded DNA; thus, the combination of the two instead of using traditional molecular beacon (MB)-labeled fluorophores and quencher groups can effectively reduce the cost of experiments while efficiently reducing the background noise. Performance testing experiments confirmed the stability and selectivity of the platform; the limits of detection (LODs) of Ag+ and Hg2+ were 1.41 nM and 1.79 nM, respectively, and the detection range were within the WHO standards. In addition, only some base sequences in the flexible functional domain of the nanoloop needed to be programmed to build a universal platform, which was feasible using TC as a target. Therefore, the designed nanomodule has the potential to detect various types of targets, such as antibiotics, proteins, and target genes, and has broad application prospects in environmental monitoring, food testing, and disease diagnosis.

Development of a new near-infrared, spectrophotometric, and colorimetric probe based on phthalocyanine containing mercaptoquinoline unit for discriminative and highly sensitive detection of Ag+, Cu2+, and Hg2+ ions

A new near-infrared, spectrophotometric, and colorimetric probe based on a phthalocyanine-containing mercaptoquinoline unit (MQZnPc) has been constructed and utilized for discriminative and highly selective/sensitive detection of Ag⁺, Cu²⁺, and Hg²⁺ ions by using proper masking agents like EDTA, KI, and NaCl. The probe only responds to Ag⁺, Cu²⁺, and Hg²⁺ among the tested ions without any interference. The probe performs quite well (the limit of detection: 160 ppb, 148 ppb, and 276 ppb of Ag⁺, Cu²⁺, and Hg²⁺ions for UV-Vis, and 15 ppb, 37 ppb, and 467 ppb of Ag⁺, Cu²⁺, and Hg²⁺ ions for fluorescence, respectively), and has a fast response time (150 sec, 90 sec, and 90 sec of Ag⁺, Cu²⁺, and Hg²⁺ions for UV-Vis, and 300 sec, 240 sec, and 90 sec Ag⁺, Cu²⁺, and Hg²⁺ions for fluorescence, respectively). The probe also displays a colorimetric feature for UV-Vis and smartphone applications. Based on a single probe, Ag⁺, Cu²⁺, and Hg²⁺ ions which are the main toxic water contaminants could be recognized very quickly and colorimetrically with high recovery values in tap water samples. This study stands out with its unique properties compared to the related studies in the literature.

Effect of Different Forms of Silver on Biological Objects

Silver has been known since ancient times on account of its pronounced antiseptic properties. Currently, its antibacterial, antiviral, and fungicidal properties are highly desired in the food and cosmetic industries, in medicine, and pharmacology. Silver exhibits toxic effects not only on pathogenic organisms but also on healthy cells. Over the past 20 years, nanosilver, a new form of silver, has been introduced in various areas of industry. The transition to the nanoscale form results in the revision of standard approaches to items, including those based on this element, and the emergence of such a novel research area as nanosafety. In this review, we address the history of using different forms of silver, the mechanisms of its interaction with living cells, toxic properties, biokinetic parameters, capability for accumulation in different organs, effects on cognitive functions, and the clinically known argyrosis condition. Relevant publications are critically analyzed and conclusions are drawn. The broader incorporation of such a weakly biophilic element as silver in the biosphere and ecosphere calls for our understanding of biochemical processes underlying the interaction of this element, in its different forms, with living cells and multicellular organisms.

Surface plasmon-catalyzed oxidation of 4-aminodiphenyl disulfide for determination of Ag+ ion in aqueous samples

A new sensor for determination of Ag⁺ ion (Ag⁺) by surface-enhanced Raman scattering (SERS) is reported. Gold nanoparticles (AuNPs) and 4-aminodiphenyl disulfide (APDS) were chosen as the SERS substrate and probe molecule, respectively. With the addition of Ag⁺, three new peaks (1141, 1392, and 1435 cm^-1) appeared in the SERS spectrum, indicating that the conversion of APDS to p,p'-dimercaptoazobenzene (DMAB) was achieved. As the concentration of Ag⁺ increased, the conversion of APDS to DMAB also increased and showed a good linear relationship (R² = 0.9746) in the range of 10 to 100 μM of Ag⁺. The limit of detection (LOD) was 7 μM. Compared with the traditional determination method, the SERS method is convenient and fast and requires no complicated preprocessing. Graphical abstract.

The Toxicity Phenomenon and the Related Occurrence in Metal and Metal Oxide Nanoparticles: A Brief Review From the Biomedical Perspective

Thousands of different nanoparticles (NPs) involve in our daily life with various origins from food, cosmetics, drugs, etc. It is believed that decreasing the size of materials up to nanometer levels can facilitate their unfavorable absorption since they can pass the natural barriers of live tissues and organs even, they can go across the relatively impermeable membranes. The interaction of these NPs with the biological environment disturbs the natural functions of cells and its components and cause health issues. In the lack of the detailed and comprehensive standard protocols about the toxicity of NPs materials, their control, and effects, this review study focuses on the current research literature about the related factors in toxicity of NPs such as size, concentration, etc. with an emphasis on metal and metal oxide nanoparticles. The goal of the study is to highlight their potential hazard and the advancement of green non-cytotoxic nanomaterials with safe threshold dose levels to resolve the toxicity issues. This study supports the NPs design along with minimizing the adverse effects of nanoparticles especially those used in biological treatments.

Common Gene Expression Patterns in Environmental Model Organisms Exposed to Engineered Nanomaterials: A Meta-Analysis

The use of omics is gaining importance in the field of nanoecotoxicology; an increasing number of studies are aiming to investigate the effects and modes of action of engineered nanomaterials (ENMs) in this way. However, a systematic synthesis of the outcome of such studies regarding common responses and toxicity pathways is currently lacking. We developed an R-scripted computational pipeline to perform reanalysis and functional analysis of relevant transcriptomic data sets using a common approach, independent from the ENM type, and across different organisms, including Arabidopsis thaliana, Caenorhabditis elegans, and Danio rerio. Using the pipeline that can semiautomatically process data from different microarray technologies, we were able to determine the most common molecular mechanisms of nanotoxicity across extremely variable data sets. As expected, we found known mechanisms, such as interference with energy generation, oxidative stress, disruption of DNA synthesis, and activation of DNA-repair but also discovered that some less-described molecular responses to ENMs, such as DNA/RNA methylation, protein folding, and interference with neurological functions, are present across the different studies. Results were visualized in radar charts to assess toxicological response patterns allowing the comparison of different organisms and ENM types. This can be helpful to retrieve ENM-related hazard information and thus fill knowledge gaps in a comprehensive way in regard to the molecular underpinnings and mechanistic understanding of nanotoxicity.

Development of a transparent, non-cytotoxic, silver ion-exchanged glass with antimicrobial activity and low ion elution

We investigated the antimicrobial, cytotoxicity, skin irritation, and ion elution behaviors of glass doped with silver ions with respect to its application to electronic equipment such as phones and tablet screens. The microbes tested were Escherichia coli, Staphylococcus aureus, and Penicillium funiculosum. AgNO3 powder was spread on both sides of aluminosilicate glass, and it was heated to 250-280°C for 10min. Under optimized heating conditions (260°C, 10min), the antimicrobial activity of ion-exchanged glass against bacteria and fungi was over 99.9% after 24 weeks. The glass failed to irritate the skin of experimental animals and was considered non-cytotoxic. The maximum amount of Ag ions that were eluted from the ion-exchanged glass into drinking water was measured at 0.037±0.003μgL(-1), an amount which is several orders of magnitude below the standard limit of 0.1mgL(-1) in drinking water. Ag ion-exchanged glass had characteristics suitable for use as a display screen, such as a light transmittance of 90% and a surface roughness of 0.704nm. Our findings suggest that glass doped with silver ions is more hygienic than non-doped glass is, and should be applied to display screens and glassware.

Oral toxicity of silver ions, silver nanoparticles and colloidal silver--a review

Orally administered silver has been described to be absorbed in a range of 0.4-18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue-grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose-dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached.

A Simple and Sensitive Colorimetric Detection of Silver Ions Based on Cationic Polymer-Directed AuNPs Aggregation

This paper describes a simple and sensitive colorimetric sensor employing single-stranded DNA (ssDNA) ligand, cationic polymer, and gold nanoparticles (AuNPs) to detect silver ions. The positively charged polymer can electrostatically interact with ssDNA and destroy the charge balance leading to induction of AuNP aggregation. Silver ions (Ag+) can bind to cytosine (C)-rich nucleic acids to form the C-Ag+-C hair-pin structure, which can prevent its interaction with polymers. The resulting cationic polymer could aggregate AuNPs causing a remarkable change in colour. The concentration of Ag+ can be determined visually. This sensing platform exhibits high sensitivity and selectivity towards Ag+ versus other metal ions, with a detection limit of 48.6 nM. The assay did not require any labelling or modifying steps. This method is simple, effective, and convenient and can in principle be used to detect other metal ions or small molecules.

Experimental switching of copper status in laboratory rodents

There is an emerging link between copper metabolism, tumor growth and efficiency of antitumor treatment with platinum drugs or copper chelators. So there is an urgent need for well-defined and reproduced animal models with different states of copper metabolism. In the present study an animal model (rats and mice) with switching copper status in blood serum (copper concentration, oxidase activity and ceruloplasmin (Cp) protein content) is characterized. The drop of copper status is caused by addition of AgCl to fodder (Ag-animals). In rats and mice, the influence of silver ions on oxidase and ferroxidase activity of blood serum is similar, but copper concentration is reduced by 90% in rats, and by 60% in mice. The absorbed silver ions are transported to liver cells and included to Cp polypeptides, which are secreted to blood serum then. Cp, which circulates in bloodstream of Ag-animals contains silver atoms, and is misfolded, as judged by circular dichroism spectroscopy and differential scanning calorimetry. Single intraperitoneal or per oral injection of Cu(II) salt to Ag-animals causes recovery of oxidase and ferroxidase activity of blood serum within 4 hours in both rodent species, presumably by rapid metabolic insertion of copper into forming Cp in liver. The recovered copper status persists for 3 days under the continuing Ag-diet. The possibilities of use of Ag-rodents with switching copper status in investigation of influence of copper status on tissue-specific intracellular copper metabolism and role of copper in tumor genesis, bone metabolism and neurodegenerative diseases are discussed.

Inhibition of large-conductance Ca2+-activated K+ channels by nanomolar concentrations of Ag+

Silver has been widely used in various medical products because of its antibacterial properties. However, there is only limited information concerning silver-related cytotoxicity. In this study we show that Ag(+) at low nanomolar concentrations (<10 nM) strongly inhibits the activity of large-conductance Ca(2+)-activated K(+) channels (BK) (Slo1), a widely expressed and physiologically important potassium channel. The Ag(+) inhibition is caused by irreversible modification on cytosolically accessible parts of the BK channel. At least four intracellular cysteines are involved in this process. In addition, at least one of these key cysteines is not accessible to the bulkier thiolate-active reagent [2-(trimethylammonium)ethyl] methanethiosulfonate bromide. One of the cysteine-less constructs generated in this study shows gating properties similar to wild-type BK channel but with much lower Ag(+) sensitivity, in which the Ag(+) modification rate was decreased by approximately 20-fold. The results from the present study suggest a possible contribution of BK channel inhibition to the cytotoxicity of Ag(+) in humans and other species.

Critical Observations on the Neurotoxicity of Silver

Silver is a xenobiotic element with no recognized trace metal value in the human body. It is absorbed into the body through the lungs, gastrointestinal tract, mucus membranes of the urinogenital tract, and through the skin, mainly in the form of silver protein complexes. Although silver is metabolized throughout the soft tissues, available evidence from experimental animal studies and human clinical reports has failed to unequivocally establish that it enters tissues of the central nervous system or is a cause of neurotoxic damage. Argyria characterized by deposition of particles of silver sulfide or silver selenide is the principle contraindication for using silver in medical devices or occupationally. This presents discoloration of the skin but is not regarded as a health risk or manifestation of toxicity. No evidence is available to demonstrate the toxic risk of silver to the peripheral nervous system, although silver sulfide deposits have been identified in the region of cutaneous nerves. Transitory silver sulfide deposits seen in the tissues of the blood-brain and blood-CSF barriers are mostly lysosomally bound or deposited on basement membranes or collagen without toxic effect. Silver is mostly excreted from the body in the urine and feces. Further research is indicated to evaluate the role of metal binding proteins including metallothioneins as cytoprotectants for neurological tissue.