Severe generalized argyria secondary to ingestion of colloidal silver protein

Drug-Induced Pigmentation: A Review

Drug-induced pigmentation (DIP) is estimated to account for 20% of all cases of acquired hyperpigmentation. Over 50 agents have been implicated, including antibiotics, antimalarials, antiretrovirals, antipsychotics, prostaglandin analogs, heavy metals, and chemotherapeutic agents. The skin, mucosal surfaces, nails, and hair can all be affected, with the color, distribution, onset, and duration of pigmentation varying between offending agents. Both a thorough physical examination and medication history are necessary to determine the offending agent. In terms of mechanism, DIP occurs most frequently through the accumulation of melanin within the dermis but also by drug accumulation, pigment synthesis, and iron deposition. Photoprotection, including applying a broad-spectrum sunscreen, wearing photoprotective clothing, and seeking shade, plays an important role in the prevention of exacerbation of DIP. Multiple lasers, including the picosecond alexandrite, Q-switched Nd:YAG, Q-switched alexandrite, and Q-switched ruby lasers, have been successful in obtaining clearance of DIP. In this review, we examine the unique characteristics of each of the inciting agents in terms of incidence, clinical presentation, time to onset and resolution, and pathogenesis.

Approach to the so-called "Invisible Dermatosis": When Subtle Histopathological Findings Guide Diagnosis

ABSTRACT

Invisible dermatosis is a concept that can be applied either to clinical or histopathological findings. We will focus on the dermatopathological aspect of this invisible dermatosis that can be seen as dermatosis with subtle histopathological findings that are mandatory to known to stablish the diagnosis. With a proper approach facing in depth the different skin layers from stratum corneum to subcutaneous tissue combined with some especial stains, special investigations and mostly a proper clinicopathological correlation, the problem of missing out a diagnosis can be decreased. We will review the general aspects for diagnosis and the peculiar findings of an in-depth review of them because it is important to note that minor changes on a skin biopsy do not mean it is disease free. We will review classic clues, we will add some new useful ones, and we will also provide a guide on the special stains helpful, such as periodic acid-Schiff when facing fungi, orcein-Giemsa and van Gieson when altered elastic fibers are suspected, or Pearl and Masson Fontana when an altered skin pigmentation is suspected.

Nanosilver inhibits the progression of pancreatic cancer by inducing a paraptosis-like mixed type of cell death

Silver has been in clinical use since ancient times and silver nanoparticles (AgNPs) have attracted attention in cancer therapy. We investigated the mechanisms by which AgNPs inhibit pancreatic ductal adenocarcinoma (PDAC). AgNPs were synthesized and 3 human PDAC and 2 nonmalignant primary cell lines were treated with AgNPs. MTT, MAPK, colony, spheroid and scratch assays, Western blotting, TEM, annexin V, 7-AAD, and H2DCFDA staining, FACS analysis, mRNA array and bioinformatics analyses, tumor xenograft transplantation, and immunohistochemistry of the treated cells were performed. We found that minimal AgNPs amounts selectively eradicated PDAC cells within a few hours. AgNPs inhibited cell migration and spheroid and colony formation, damaged mitochondria, and induced paraptosis-like cell death with the presence of cytoplasmic vacuoles, dilation of the ER and mitochondria, ROS formation, MAPK activity, and p62 and LC3b expression, whereas effects on the nucleus, DNA fragmentation, or caspases were not detectable. AgNPs strongly decreased tumor xenograft growth without side effects and reduced the expression of markers for proliferation and DNA repair, but upregulated paraptosis markers. The results highlight nanosilver as complementary agent to improve the therapeutic efficacy in pancreatic cancer.

Antiviral effects of coinage metal-based nanomaterials to combat COVID-19 and its variants

The world has been suffering from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, and millions of people have been infected through human-to-human transmission and lost their lives within months. Although multidisciplinary scientific approaches have been employed to fight against this deadly pandemic, various mutations and diverse environments keep producing constraints in treating SARS-CoV-2. Indeed, the efficacy of the developed vaccines has been limited, and inoculation with the vaccines does not guarantee complete protection even though multiple doses are required, which is a frustrating process. Historically, coinage metals (Cu, Ag, and Au) have been well-known for their effectiveness in antiviral action as well as good biocompatibility, binding receptor inhibition, reactive oxygen species, and phototherapy properties. Thus, this review highlights the diagnostic and therapeutic mechanisms of SARS-CoV-2 using the antivirus ability and mode of action of coinage metals such as viral entry mechanisms into host cells and the NP-inhibition process, which are explained in detail. This article also draws attention to coinage metal nanomaterial-based approaches to treat other contagious viruses. In addition, coinage metal-based biosensors and an overview of some other biocompatible metal-based nanomaterials to fight against SARS-CoV-2 variants are discussed. Finally, the advantages, perspectives and challenges of coinage metal nanoparticles are given to fight against viral infections in the future.

Alpha-Lipoic Acid Prevents Side Effects of Therapeutic Nanosilver without Compromising Cytotoxicity in Experimental Pancreatic Cancer

Silver nanoparticles (AgNPs) have attracted attention in cancer therapy and might support the treatment of pancreatic ductal adenocarcinoma (PDAC). Silver is in clinical use in wound dressings, catheters, stents and implants. However, the side effects of systemic AgNP treatment due to silver accumulation limit its therapeutic application. We evaluated whether the antioxidant and natural agent α-lipoic acid might prevent these side effects. We synthesized AgNPs using an Ionic-Pulser® Pro silver generator and determined the concentration by inductively coupled plasma-optical emission spectrometry. The effect of α-lipoic acid was examined in four PDAC and two nonmalignant cell lines by MTT, FACS analysis, TEM, xenotransplantation and immunohistochemistry. The viability of PDAC cells was nearly totally abolished by AgNP treatment, whereas nonmalignant cells largely resisted. α-Lipoic acid prevented AgNP-induced cytotoxicity in nonmalignant cells but not in PDAC cells, which might be due to the higher sensitivity of malignant cells to silver-induced cytotoxicity. α-Lipoic acid protected mitochondria from AgNP-induced damage and led to precipitation of AgNPs. AgNPs reduced the growth of tumor xenografts, and cotreatment with α-lipoic acid protected chick embryos from AgNP-induced liver damage. Together, α-lipoic acid strongly reduced AgNP-induced side effects without weakening the therapeutic efficacy.

The Antimicrobial Properties of Modified Pharmaceutical Bentonite with Zinc and Copper

Pharmaceutical grade bentonite, containing a high amount of montmorillonite, enriched with zinc (Zn) or copper (Cu) (ZnBent and CuBent, respectively) was used as the main component for the creation of formulations for cutaneous use and tested for their antimicrobial capacity. Bentonite (Bent) with added phenoxyethanol (PH) as a preservative and unmodified bentonite were used as control groups. The mineralogical composition, structural state, and physical or chemical properties, before and after the modification of the samples, were characterized utilizing X-ray Diffraction Analysis (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Fluorescence (XRF) techniques, and Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM, SEM-EDS) analyses. In addition, the profile of zinc and copper concentration from two types of surfaces ZnBent and CuBent, and into Phosphate-Buffered Saline (PBS) are discussed. Finally, the formulations in the form of basic pastes were challenged against bacteria, molds, and yeasts, and their performance was evaluated based on the European Pharmacopeia criteria. The Cu-modified bentonite performed excellently against bacteria and yeasts, while the Zn-modified bentonite only showed great results against yeasts. Therefore, Cu-modified bentonite formulations could offer antimicrobial protection without the use of preservatives.

Fate and transformation of silver nanoparticles in different biological conditions

The exploitation of silver nanoparticles (AgNPs) in biomedicine represents more than one third of their overall application. Despite their wide use and significant amount of scientific data on their effects on biological systems, detailed insight into their in vivo fate is still lacking. This study aimed to elucidate the biotransformation patterns of AgNPs following oral administration. Colloidal stability, biochemical transformation, dissolution, and degradation behaviour of different types of AgNPs were evaluated in systems modelled to represent biological environments relevant for oral administration, as well as in cell culture media and tissue compartments obtained from animal models. A multimethod approach was employed by implementing light scattering (dynamic and electrophoretic) techniques, spectroscopy (UV-vis, atomic absorption, nuclear magnetic resonance) and transmission electron microscopy. The obtained results demonstrated that AgNPs may transform very quickly during their journey through different biological conditions. They are able to degrade to an ionic form and again reconstruct to a nanoparticulate form, depending on the biological environment determined by specific body compartments. As suggested for other inorganic nanoparticles by other research groups, AgNPs fail to preserve their specific integrity in in vivo settings.

Histopathological Changes of Organs (Lungs, Liver, Kidney, and Brain) After Using Two Types of AgiCoat and Acticoat Nanosilver Dressings on Deep Second-Degree Burn in Rat

Prevention of infections is a very important issue in treating the burn wounds. The nanosilver dressings have many promising advantages, but absorption of silver ions and its adverse effects to the body were always a question. The aim of this study was to compare Silver serum levels and acute toxic effects of nanosilver on histopathology of organs (lungs, liver, kidney, spleen, and brain) in two types of AgiCoat and Acticoat (nanosilver) dressings on second-degree deep burn in rat. This is an experimental study conducted in our animal laboratory. We divided 24 Sprague-Dawley male rats weighing 300 to 350 randomly into two groups. After anesthesia, a second deep-degree burn was made over dorsal skins of rats by standard method. For group A, Agicoat and, for group B, Acticoat dressings were used. The dressings were changed every 3 days with AgiCoat and Acticoat, respectively. After 14 days, we got blood samples and tissue samples taken from heart, liver, kidneys, spleen, lungs, and brain and a sample from dorsal skin of the rat for histopathological examinations. The results showed that the levels of serum silver in both groups were significantly higher than the standard level (1.22 part per million (PM); AgiCoat, P = .017; Acticoat, P = .000), but there was no significant difference between the groups (P = .551). Examination of the relationship between the level of serum silver and histopathological changes in liver showed that hepatotoxicity of AgiCoat was higher compared with Acticoat and the difference was significant (P = .002). There were no pathological changes in brain, kidneys, spleen, heart, and lungs. Wound healing was faster in Acticoat group. The nanosilver dressings can cause toxicity in liver but not in kidney, brain, spleen, heart, and lungs. Liver pathology and hepatotoxicity were more prominent in AgiCoat group. Wound healing was faster in Acticoat group.

Clinical and Forensic Aspects of the Different Subtypes of Argyria

Argyria encompasses the different cosmetic alterations that can develop if enough silver particles deposit in a specific tissue, typically in the skin, ranging from localized dark-blue macules to a generalized slate-gray/bluish tinge following systemic absorption. This work aims to fully review the state of the art regarding pathophysiology, diagnosis, treatment, and relevant clinical and forensic features of argyria. Argyria has been diagnosed in a wide range of ages, both sexes and varied ethnicities, with no known individual predisposing factors. Ultraviolet radiation with subsequence increases of melanin production aggravates the discoloration due to a reduction in the silver deposits. Physical examination and silver exposure in the anamnesis can be highly suggestive of the diagnosis, but a histopathological analysis with Energy-Dispersive X-ray Spectroscopy is required to unequivocally determine the discoloration etiology. Safe and effective treatment has only been accomplished with laser techniques, though only a few cases have been reported and with limited follow-up time. In conclusion, argyria typically has an occupational or iatrogenic etiology. It should be suspected when a patient presents with typical skin or eye lesions. A seemingly viable treatment modality, with laser technology, is finally within the horizon.

A clinical mimicker of melanoma with distinctive histopathology: Topical silver nitrate exposure

Exposure to silver-containing compounds can result in reversible discoloration of the skin, presenting as an irregular brown or black macule, which can have a clinical appearance similar to melanoma. Both the clinical scenario and the histopathology are unique. Silver nitrate darkens with exposure to light, and the area can appear to change over time. On microscopic examination, there are coarse pigmented granules dispersed throughout the corneal layer, and largely absent from the remainder of the epidermis-although the precise location may depend on the duration of topical exposure. While argyria, its irreversible counterpart, has been well-characterized, only a single source has previously reported the histopathology of transient topical silver nitrate exposure. We present two cases, review the clinical and histopathologic differentials, and detail the distinctive histopathology that enables a diagnosis to be suggested in this clinical mimicker of melanoma.

Argyria, an Unexpected Case of Skin Discoloration From Colloidal Silver Salt Ingestion

BACKGROUND

Argyria is a rare condition characterized by gray/blue dislocation of the skin caused by chronic exposure to silver salts.

CASE REPORT

We review the case of an 81-year-old man who presented to the emergency department after a motor vehicle accident, was incidentally found to have skin discoloration, and was ultimately diagnosed with argyria. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although most emergency physicians will not complete a toxicology fellowship, all emergency physicians are on the front line of toxicological presentations and should be able to recognize argyria and differentiate this condition from other causes of skin discoloration.

Silver nasal sprays: Misleading Internet marketing

Long-term use of silver-containing products is associated with a permanent bluish-gray discoloration of the skin known as argyria, but they remain widely available despite several measures by the FDA to regulate them. Several recent case reports have described the occurrence of argyria as a result of using these “natural” products. We used the five most common Internet search engines to find Web sites providing information on silver-containing nasal sprays. Of 49 Web sites analyzed, only 2 (4%) mentioned argyria as a possible complication, although 30 (61 %) did caution against long-term use. Eight sites (16%) made specific claims about the health benefits of the product. All 49 sites (100%) provided direct or indirect links to buy silver-containing nasal sprays. We conclude that information about silver-containing nasal sprays on the Internet is misleading and inaccurate. Therefore, otolaryngologists should be aware of the misinformation their patients may be receiving about these products.

Acute myeloid leukemia with complex cytogenetic abnormalities associated with long-term use of oral colloidal silver as nutritional supplement – Case report and review of literature

We report a case of acute myeloid leukemia with complex cytogenetic abnormalities suggestive of preexisting myelodysplastic syndrome in a patient with habitual ingestion of colloidal silver as nutritional supplement for over 10 years and the medical literature is reviewed.

A Rare Case of Localized Argyria on the Face

Due to its antibacterial actions, silver sulfadiazine is widely used as a topical agent in the treatment of wounds, including burns. Widespread or prolonged topical application of silver sulfadiazine dressings can lead to argyria including systemic symptoms due to the resorption of silver. Here, we report a patient experiencing localized argyria due to sunlight exposure after topical use of silver sulfadiazine cream on his face.

An Update on Drug-Induced Pigmentation

Drug-induced pigmentation accounts for up to 20% of all cases of acquired pigmentation. A thorough review of medical history and previous and ongoing medications as well as a complete skin examination can guide diagnosis. Implicated agents include alkylating/cytotoxic agents, analgesics, antiarrhythmics, anticoagulants, antiepileptics, antimalarials, antimicrobials, antiretrovirals, metals, prostaglandin analogs, and psychotropic agents, among others. Confirming true drug associations can be challenging, especially in the setting of delayed onset of pigmentation and coexisting polypharmacy.

Nanosilver-Enabled Food Storage Container Tradeoffs: Environmental Impacts Versus Food Savings Benefit, Informed by Literature

Globally, thousands of tons of food are lost each year due to spoilage and degraded quality. This loss is a current critical issue that must be addressed to ensure adequate food supply for the growing world population; the use of technology and regulatory practices are avenues to a solution. One considered approach is the reduction of the microorganism population on the surface of food products to delay spoilage through the use of antimicrobials. One current method is the use of the antimicrobial properties of nanoscale silver (nAg) particles to prolong the freshness of stored food by reducing the bacteria present. Nanoscale silver-enabled food storage containers present a potential solution to the food loss problem; nevertheless, their environmental and human health effects have been questioned by the scientific community. Literature is used to generate data for the life cycle impact assessment of these types of products and their corresponding environmental effects. The benefits of nAg-enabled food storage containers are considered with respect to their potential to extend the shelf life of stored food and prevent food spoilage. The results illustrate that the environmental effects of nano-enabling food storage containers with silver is small (when the initial silver concentration is relatively low, less than 1% by mass) compared with the overall environmental effects of food storage containers and also relatively small compared with the environmental effects of producing the stored food. This finding suggests that the added environmental burden of nano-enabling food storage containers may be small when compared with the environmental burden of food losses. Integr Environ Assess Manag 2018;14:769-776. © 2018 SETAC.

Transformation and Speciation Analysis of Silver Nanoparticles of Dietary Supplement in Simulated Human Gastrointestinal Tract

Knowledge of the physicochemical properties of ingestible silver nanoparticles (AgNPs) in the human gastrointestinal tract (GIT) is essential for assessing their bioavailability, bioactivity, and potential health risks. The gastrointestinal fate of AgNPs and silver ions from a commercial dietary supplement was therefore investigated using a simulated human GIT. In the mouth, no dissolution or aggregation of AgNPs occurred, which was attributed to the neutral pH and the formation of biomolecular corona, while the silver ions formed complexes with biomolecules (Ag-biomolecule). In the stomach, aggregation of AgNPs did not occur, but extensive dissolution was observed due to the low pH and the presence of Cl^-. In the fed state (after meal), 72% AgNPs (by mass) dissolved, with 74% silver ions forming Ag-biomolecule and 26% forming AgCl. In the fasted state (before meal), 76% AgNPs dissolved, with 82% silver ions forming Ag-biomolecule and 18% forming AgCl. A biomolecular corona around AgNPs, comprised of mucin with multiple sulfhydryl groups, inhibited aggregation and dissolution of AgNPs. In the small intestine, no further dissolution or aggregation of AgNPs occurred, while the silver ions existed only as Ag-biomolecule. These results provide useful information for assessing the bioavailability of ingestible AgNPs and their subsequently potential health risks, and for the safe design and utilization of AgNPs in biomedical applications.

Silver Nanomaterials in Contemporary Molecular Physiology Research

Silver nanoparticles have numerous potential applications in engineering, industry, biology and medicine. Because of their unique chemical properties, they have become the focus of many research teams all over the world. Silver nanoparticles may exhibit significant antimicrobial and anticancer effects, and they may be a valuable part of various bioassays and biosensors. However, the research on biological and medical uses of AgNPs is related with numerous potential problems and challenges that need to be overcome in the years ahead. Possible toxic effects of silver nanoparticles on living organisms represent a great concern, both in clinical medicine and public health. Nevertheless, in the future, it may be expected that all metallic nanomaterials, including the ones made from silver will greatly benefit almost all natural scientific fields. In this short review, we focus on the recent research on silver nanoparticles in experimental physiology, as well as other areas of fundamental and clinical medicine.

Synergistic mechanism of Ag+-Zn2+ in anti-bacterial activity against Enterococcus faecalis and its application against dentin infection

Background

Ag⁺ and Zn²⁺ have already been used in combinations to obtain both enhanced antibacterial effect and low cytotoxicity. Despite this, it is still unclear how the Zn²⁺ co-works with Ag⁺ in the synergistic antibacterial activity. The main purposes of this study were to investigate the co-work pattern and optimum ratio between Ag⁺ and Zn²⁺ in their synergistic antibacterial activity against E. faecalis, the possible mechanisms behind this synergy and the primary application of optimum Ag⁺–Zn²⁺ co-work pattern against the E. faecalis biofilm on dentin. A serial of Ag⁺–Zn²⁺ atomic combination ratios were tested on both planktonic and biofilm-resident E. faecalis on dentin, their antibacterial efficiency was calculated and optimum ratio determined. And the cytotoxicity of various Ag⁺–Zn²⁺ atomic ratios was tested on MC3T3-E1 Cells. The role of Zn²⁺ in Ag⁺–Zn²⁺co-work was evaluated using a Zn²⁺ pretreatment study and membrane potential—permeability measurement.

Results

The results showed that the synergistically promoted antibacterial effect of Ag⁺–Zn²⁺ combinations was Zn²⁺ amount-dependent with the 1:9 and 1:12 Ag⁺–Zn²⁺ atomic ratios showing the most powerful ability against both planktonic and biofilm-resident E. faecalis. This co-work could likely be attributed to the depolarization of E. faecalis cell membrane by the addition of Zn²⁺. The cytotoxicity of the Ag⁺–Zn²⁺ atomic ratios of 1:9 and 1:12 was much lower than 2% chlorhexidine.

Conclusions

The Ag⁺–Zn²⁺ atomic ratios of 1:9 and 1:12 demonstrated similar strong ability against E. faecalis biofilm on dentin but much lower cytotoxicity than 2% chlorhexidine. New medications containing optimum Ag⁺–Zn²⁺ atomic ratios higher than 1:6, such as 1:9 or 1:12, could be developed against E. faecalis infection in root canals of teeth or any other parts of human body.

Antifungal efficacy of Au@ carbon dots nanoconjugates against opportunistic fungal pathogen, Candida albicans

In the current study, we have investigated the toxicological effect of a novel hydrophilic nanoconjugate gold@carbon dot (Au@CD) and carbon dots (CDs) on the opportunistic fungal pathogen, Candida albicans. A homogenous experimental analysis was conducted for determining the toxicity of Au@CDs nanoconjugates of five different sizes ranging from 22 ± 2 to 35 ± 3 nm prepared using the carbon dots of mean hydrodynamic radius 12 ± 1 nm. The smallest size of nanoconjugate was synthesized using 0.3 mg ml^-1 HAuCl₄ precursor. Our study for the first time, conclusively establishes the size-dependent toxicity effect of these characterized nanoconjugates against the abovementioned fungal pathogen. The MIC₈₀ value of smaller sized Au@CDs nanoconjugates, S1-S3 samples were 250, 500 and 500 μg ml^-1, respectively, while nanoconjugates of R_h diameter greater than 30 nm (S4 and S5 samples) did not show any toxicity. The results thus demonstrate that alteration in composition (carbon vs Au@CDs) exhibits a profound effect on the susceptibility of Candida albicans cells. While a size-dependent toxicity was observed for the nanoconjugates, CDs were found to be quite toxic owing to their small size which facilitated their entry into the cells and challenged the biocompatibility of carbon allotropes.

Biological evaluation of silver nanoparticles incorporated into chitosan-based membranes

AIM

To evaluate the antibacterial potential and biological performance of silver nanoparticles in chitosan-based membranes.

MATERIALS & METHODS

Electrospun chitosan/poly(ethylene oxide) membranes with different amounts of silver nanoparticles were evaluated for antibacterial properties and cytotoxicity in vitro and for tissue response in a rabbit subcutaneous model.

RESULTS

The nanoparticles displayed dose-dependent antibacterial properties against Porphyromonas gingivalis and Fusobacterium nucleatum, without showing noticeable cytotoxicity. The membranes with silver nanoparticles evoked a similar inflammatory response compared with the membranes without silver nanoparticles.

CONCLUSION

The antibacterial effect, combined with the findings on cyto- and biocompatibility warrants further investigation to the usefulness of chitosan/poly(ethylene oxide) membranes with silver nanoparticles, for clinical applications like guided tissue regeneration.

Widespread and Indiscriminate Nanosilver Use: Genuine Potential for Microbial Resistance

In this era of increasing antibiotic resistance, the use of alternative antimicrobials such as silver has become more widespread. Superior antimicrobial activity has been provided through fabrication of silver nanoparticles or nanosilver (NAg), which imparts cytotoxic actions distinct from those of bulk silver. In the wake of the recent discoveries of bacterial resistance to NAg and its rising incorporation in medical and consumer goods such as wound dressings and dietary supplements, we argue that there is an urgent need to monitor the prevalence and spread of NAg microbial resistance. In this Perspective, we describe how the use of NAg in commercially available products facilitates prolonged microorganism exposure to bioavailable silver, which underpins the development of resistance. Furthermore, we advocate for a judicial approach toward NAg use in order to preserve its efficacy and to avoid environmental disruption.

Silver-Containing Hydroxyapatite Coating Reduces Biofilm Formation by Methicillin-Resistant Staphylococcus aureus In Vitro and In Vivo

Biofilm-producing bacteria are the principal causes of infections associated with orthopaedic implants. We previously reported that silver-containing hydroxyapatite (Ag-HA) coatings exhibit high antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). In the present study, we evaluated the effects of Ag-HA coating of implant surfaces on biofilm formation. Titanium disks (14-mm diameter, 1-mm thickness), one surface of which was coated with HA or 0.5%-3.0% Ag-HA with a thermal spraying technique, were used. In vitro, the disks were inoculated with an MRSA suspension containing 4 × 10⁵ CFU and incubated for 1-2 weeks. In vivo, MRSA-inoculated HA and 3% Ag-HA disks (8.8-10.0 × 10⁸ CFU) were implanted subcutaneously on the back of rats for 1-7 days. All disks were subsequently stained with a biofilm dye and observed under a fluorescence microscope, and biofilm coverage rates (BCRs) were calculated. The BCRs on the Ag-HA coating were significantly lower than those on the HA coating at all time points in vitro (p < 0.05). Similar results were observed in vivo (p < 0.001) without argyria. Ag-HA coating reduced biofilm formation by MRSA in vitro and in vivo; therefore, Ag-HA coating might be effective for reducing implant-associated infections.

Evaluating the toxicity of silver nanoparticles by detecting phosphorylation of histone H3 in combination with flow cytometry side-scattered light

Post-translational modification of histones is linked to a variety of biological processes and disease states. This paper focuses on phosphorylation of histone H3 at serine 10 (p-H3S10), induced by silver nanoparticles (AgNPs) and discusses the usefulness of p-H3S10 as a marker to evaluate the toxicity of AgNPs. Cultured human cells showed remarkable p-H3S10 immediately after treatment with AgNPs but not with Ag microparticles. p-H3S10 lasts up to 24 h and strongly depends upon the cellular uptake of AgNPs. Removal of Ag ions suppressed p-H3S10, while adding an excess of Ag ions augmented p-H3S10. We expected that p-H3S10 requires two events: cellular uptake of AgNPs and continuous release of Ag ions from intracellular AgNPs. AgNPs enhanced the expression of the proto-oncogene c-jun, and p-H3S10 increased in the promoter sites of the gene, indicating that p-H3S10 might indicate a biological reaction related to carcinogenesis. We previously showed that side-scattered light from flow cytometry could be used to measure the uptake potential of nanoparticles [ Suzuki , H. ; Toyooka , T. ; Ibuki , Y. Simple and easy method to evaluate uptake potential of nanoparticles in mammalian cells using a flow cytometric light scatter analysis . Environ. Sci. Technol. 2007 , 41 ( 8 ), 3018 - 3024 ]. Our current findings suggest that p-H3S10 can be used to evaluate the toxicity of AgNPs and Ag ion release in combination with detection of side-scattered light from flow cytometry.

Ultrastructural analysis of Candida albicans when exposed to silver nanoparticles

Candida albicans is the most common fungal pathogen in humans, and recently some studies have reported the antifungal activity of silver nanoparticles (AgNPs) against some Candida species. However, ultrastructural analyses on the interaction of AgNPs with these microorganisms have not been reported. In this work we evaluated the effect of AgNPs on C. albicans, and the minimum inhibitory concentration (MIC) was found to have a fungicidal effect. The IC₅₀ was also determined, and the use of AgNPs with fluconazole (FLC), a fungistatic drug, reduced cell proliferation. In order to understand how AgNPs interact with living cells, the ultrastructural distribution of AgNPs in this fungus was determined. Transmission electron microscopy (TEM) analysis revealed a high accumulation of AgNPs outside the cells but also smaller nanoparticles (NPs) localized throughout the cytoplasm. Energy dispersive spectroscopy (EDS) analysis confirmed the presence of intracellular silver. From our results it is assumed that AgNPs used in this study do not penetrate the cell, but instead release silver ions that infiltrate into the cell leading to the formation of NPs through reduction by organic compounds present in the cell wall and cytoplasm.

Synthesis of silver nanoparticles by green method stabilized to synthetic human stomach fluid

Silver nanoparticles (Ag NP) have been attracted much attention in recent years in biomedical applications due to their antimicrobial activity, but their drawbacks include toxicity and instability to aqueous hydrochloric acid solutions. Ag NPs have now been successfully prepared by a simple and “green” synthesis method by reducing Ag⁺ ions in the presence of modified poly(vinyl alcohol) thiol (PVA-SH) in aqueous acidic solution. In this respect, Ag NPs were stabilized by coating different types of citrate-reduced Ag NPs with different weight ratios (1–3 Wt. %) of PVSH derivatives. The as-prepared Ag NPs were characterized using UV-Visible, high resolution transmission electron microscopy/ energy dispersive X-ray spectroscopy (TEM/EDS), dynamic light scattering (DLS) and X-ray powder diffraction (XRD) combined with Rietveld analysis. The changes in size, shape, and hydrodynamic diameter of Ag NPs after different duration exposure to synthetic stomach fluid (SSF) and1 M HCl were determined using TEM, XRD and UV-Visible analyses. The data indicated that these Ag NPs possessed high stability to SSF for more than 90 days, which was not previously reported in the literature.

Acute and subacute toxicity in vivo of thermal-sprayed silver containing hydroxyapatite coating in rat tibia

To reduce the incidence of implant-associated infection, we previously developed a novel coating technology using hydroxyapatite (HA) containing silver (Ag). This study examined in vivo acute and subacute toxicity associated with the Ag-HA coating in rat tibiae. Ten-week-old rats received implantation of HA-, 2% Ag-HA-, or 50% Ag-HA-coated titanium rods. Concentrations of silver in serum, brain, liver, kidneys, and spleen were measured in the acute phase (2-4 days after treatment) and subacute phase (4-12 weeks after treatment). Biochemical and histological examinations of those organs were also performed. Mean serum silver concentration peaked in the acute phase and then gradually decreased. Mean silver concentrations in all examined organs from the 2% Ag-HA coating groups showed no significant differences compared with the HA coating group. No significant differences in mean levels of glutamic-oxaloacetic transaminase, glutamic-pyruvic transaminase, lactate dehydrogenase, creatinine, or blood urea nitrogen were seen between the three groups and controls. Histological examinations of all organs revealed no abnormal pathologic findings. No acute or subacute toxicity was seen in vivo for 2% Ag-HA coating or HA coating. Ag-HA coatings on implants may represent biologically safe antibacterial biomaterials and may be of value for reducing surgical-site infections related to implantation.

Argyria following the use of silver-coated megaprostheses: no association between the development of local argyria and elevated silver levels

The aims of this study were to evaluate the incidence of local argyria in patients with silver-coated megaprostheses and to identify a possible association between argyria and elevated levels of silver both locally and in the blood. Between 2004 and 2011, 32 megaprostheses with silver coatings were implanted in 20 female and 12 male patients following revision arthroplasty for infection or resection of a malignant tumour, and the levels of silver locally in drains and seromas and in the blood were determined. The mean age of the patients was 46 years (10 to 81); one patient died in the immediate post-operative period and was excluded. Seven patients (23%) developed local argyria after a median of 25.7 months (interquartile range 2 to 44.5). Patients with and without local argyria had comparable levels of silver in the blood and aspiration fluids. The length of the implant did not influence the development of local argyria. Patients with clinical evidence of local argyria had no neurological symptoms and no evidence of renal or hepatic failure. Thus, we conclude that the short-term surveillance of blood silver levels in these patients is not required.

Skin discolouration with acute onset parkinsonism secondary to systemic zirconium intoxication

A 72-year-old woman presented with suspected parkinsonism and discolouration of the skin especially on sun-exposed areas. Thorough investigation revealed systemic zirconium intoxication due to intake of metallic colloids as a home remedy as a cause of the skin colour change. There may be an association between skin discolouration and her parkinsonism. This is unique in that various clinical manifestations developed following systemic ingestion of zirconium and this should serve as a warning on the risk of taking illicit dietary supplements.

Measurement of the silver ion concentration in wound fluids after implantation of silver-coated megaprostheses: correlation with the clinical outcome

Background. Tumor patients and patients after traumas are endangered by a reduced immune defense, and a silver coating on their megaprostheses may reduce their risks of infection. The aim of this study was to determine the silver ion concentration directly measured from the periprosthetic tissue and the influence on the clinical outcome. Material and Methods. Silver ions were evaluated in 5 mL wound fluids two days postoperatively and in blood patients 7 and 14 days after surgery using inductively coupled plasma emission spectrometry in 18 patients who underwent total joint replacement with a silver-coated megaendoprosthesis. Results. The concentration of silver ions averaged 0.08 parts per million. Patients who showed an increased silver concentration in the blood postoperatively presented a lower silver concentration in the wound fluids and a delayed decrease in C-reactive protein levels. There were significantly fewer reinfections and shorter hospitalization in comparison with a group that did not receive a silver-coated megaprosthesis. Conclusion. An increased concentration of silver in the immediate surroundings of silver-coated prostheses was demonstrated for the first time in cohorts of patients with trauma or tumors. An elevated concentration of silver ions in the direct periprosthetic tissue may have reduced the infection rate.

Changes in silver nanoparticles exposed to human synthetic stomach fluid: effects of particle size and surface chemistry

The significant rise in consumer products and applications utilizing the antibacterial properties of silver nanoparticles (AgNPs) has increased the possibility of human exposure. The mobility and bioavailability of AgNPs through the ingestion pathway will depend, in part, on properties such as particle size and the surface chemistries that will influence their physical and chemical reactivities during transit through the gastrointestinal tract. This study investigates the interactions between synthetic stomach fluid and AgNPs of different sizes and with different capping agents. Changes in morphology, size and chemical composition were determined during a 30 min exposure to synthetic human stomach fluid (SSF) using Absorbance Spectroscopy, High Resolution Transmission Electron and Scanning Electron Microscopy (TEM/SEM), Dynamic Light Scattering (DLS), and Nanoparticle Tracking Analysis (NTA). AgNPs exposed to SSF were found to aggregate significantly and also released ionic silver which physically associated with the particle aggregates as silver chloride. Generally, the smaller sized AgNPs (<10nm) showed higher rates of aggregation and physical transformation than larger particles (75 nm). Polyvinylpyrrolidone (pvp)-stabilized AgNPs prepared in house behaved differently in SSF than particles obtained from a commercial source despite having similar surface coating and size distribution characteristics.

Chemical transformations of nanosilver in biological environments

The widespread use of silver nanoparticles (Ag-NPs) in consumer and medical products provides strong motivation for a careful assessment of their environmental and human health risks. Recent studies have shown that Ag-NPs released to the natural environment undergo profound chemical transformations that can affect silver bioavailability, toxicity, and risk. Less is known about Ag-NP chemical transformations in biological systems, though the medical literature clearly reports that chronic silver ingestion produces argyrial deposits consisting of silver-, sulfur-, and selenium-containing particulate phases. Here we show that Ag-NPs undergo a rich set of biochemical transformations, including accelerated oxidative dissolution in gastric acid, thiol binding and exchange, photoreduction of thiol- or protein-bound silver to secondary zerovalent Ag-NPs, and rapid reactions between silver surfaces and reduced selenium species. Selenide is also observed to rapidly exchange with sulfide in preformed Ag(2)S solid phases. The combined results allow us to propose a conceptual model for Ag-NP transformation pathways in the human body. In this model, argyrial silver deposits are not translocated engineered Ag-NPs, but rather secondary particles formed by partial dissolution in the GI tract followed by ion uptake, systemic circulation as organo-Ag complexes, and immobilization as zerovalent Ag-NPs by photoreduction in light-affected skin regions. The secondary Ag-NPs then undergo detoxifying transformations into sulfides and further into selenides or Se/S mixed phases through exchange reactions. The formation of secondary particles in biological environments implies that Ag-NPs are not only a product of industrial nanotechnology but also have long been present in the human body following exposure to more traditional chemical forms of silver.

Alterations in physical state of silver nanoparticles exposed to synthetic human stomach fluid

The bioavailability of ingested silver nanoparticles (AgNPs) depends in large part on initial particle size, shape and surface coating, properties which will influence aggregation, solubility and chemical composition during transit of the gastrointestinal tract. Citrate-stabilized AgNPs were exposed to synthetic human stomach fluid (SSF) (pH 1.5) and changes in size, shape, zeta potential, hydrodynamic diameter and chemical composition were determined during a 1h exposure period using Surface Plasmon Resonance (SPR), High Resolution Transmission Electron Microscopy/Energy Dispersive X-ray Spectroscopy (TEM/EDS), Dynamic Light Scattering (DLS) and X-ray Powder Diffraction (XRD) combined with Rietveld analysis. Exposure of AgNPs to SSF produced a rapid decrease in the SPR peak at 414nm and the appearance of a broad absorbance peak in the near infrared (NIR) spectral region. During exposure to SSF, changes in zeta potential, aggregation and morphology of the particles were also observed as well as production of silver chloride which appeared physically associated with particle aggregates.

Successful treatment of argyria using a low-fluence Q-switched 1064-nm Nd:YAG laser

BACKGROUND

Argyria is a rare skin disease caused by cutaneous deposits of silver granules as a result of exposure to silver substrates or ingestion of silver salt. This pigmentation change causes cosmetic problems, and there was previously no recognized effective treatments for argyria.

OBJECTIVE

To evaluate the treatment effect of a low-fluence Q-switched 1064-nm Nd:YAG laser on argyria.

SUBJECTS AND METHODS

Case report of a 49-year-old with a history of ingestion of a colloidal silver solution daily for approximately one year as a traditional remedy.

RESULTS

After seven sessions of treatment, the patient's skin color returned to normal.

CONCLUSION

A low-fluence Q-switched 1064-nm Nd:YAG laser provided safe and effective treatment for the skin discoloration associated with argyria.

Rapid onset of argyria induced by a silver-containing dietary supplement

We describe a 53-year-old man in good general health who presented with an 8-month history of progressive gray hyperpigmentation of the face. He denied using any prescription medications; however, he admitted to taking a herbal supplement. Clinically, the differential diagnosis included hemochromatosis, Wilson's disease and hyperpigmentation secondary to supplement use. Punch biopsies from the left forehead and preauricular region showed heavily sun-damaged skin with a minimal inflammatory infiltrate. Closer inspection, however, revealed minute scattered black/brown particles distributed in the basement membrane zone of eccrine and sebaceous glands. Similar particles were also present in hair follicles, blood vessels and arrector pili muscles. The particles did not stain with Gomori methenamine silver, Fontana-Masson or iron stains. Electron microscopy with energy-dispersive x-ray analysis showed numerous particles, less than 1 µm in greatest dimension, which showed peaks for silver and sulfur. This analytical result confirmed the impression of argyria. Further history revealed that the patient had indeed been taking a silver supplement for several months under the premise that it would boost his immune system. This case is unique in that the patient's hyperpigmentation developed in a short period of time as compared with other reports in the medical literature.

Synthesis and antimicrobial studies of silver N-heterocyclic carbene complexes bearing a methyl benzoate substituent

Due to the properties of silver as an antimicrobial, our research group has synthesized many different silver carbene complexes. Two new silver N-heterocyclic carbene complexes derived from 4,5-dichloroimidazole and theobromine bearing methyl benzoate substituents were synthesized by in situ carbene formation using silver acetate as the base in the reaction. The new compounds were fully characterized by several methods including NMR spectroscopy and X-ray crystallography. Preliminary antimicrobial efficacy studies against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli were conducted. The results of this study demonstrated antimicrobial efficacy of the two complexes comparable to silver nitrate, showing their potential for use in the treatment of bacterial infections.

A case of argyria following colloidal silver ingestion

Argyria is a rare cutaneous discoloration caused by the intake of silver or various compounds containing silver. We report a case of argyria in a 73-year-old male following ingestion of colloidal silver as an alternative medicine over 5 years. He had a diffuse, slate gray discoloration of his face and hands. A biopsy specimen from the face revealed brown-black extracellular granules in the upper dermis and between collagen bundles. We also found silver particles in the mucous of the colon. The ingestion of colloidal silver appears to be increasing among patients using alternative health practices. We report this case to bring people's attention to the problems associated with the ingestion of colloidal silver.