scholarly journals Development of a GFP Fluorescent Bacterial Biosensor for the Detection and Quantification of Silver and Copper Ions

2018 ◽  
Author(s):  
Adam R. Martinez ◽  
John R. Heil ◽  
Trevor C. Charles
Keyword(s):  
Environmental Monitoring ◽  
Copper Ions ◽  
Silver Ions ◽  
Silver Ion ◽  
Resistant Bacteria ◽  
Ion Release ◽  
Ionic Silver ◽  
Wide Range ◽  
Further Development ◽  
Detection And Quantification

AbstractIonic silver is known to be an effective antimicrobial agent widely used in the cleaning and medical industries, however, there are several concerns regarding the release of silver pollutants into the environment. Presented here are two engineered bacterial biosensors for the detection and quantification of silver. The biosensors contain a silver resistance operon and a GFP gene that is strictly regulated through silver activated regulatory regions that control expression of thesiloperons. The two biosensors are responsive to a wide range of silver ion concentrations, and a correlation between silver and GFP signal is seen at select concentration ranges. The biosensors were shown to detect silver ions released from silver nanoparticles, and have the potential to become a method for monitoring ion release rates of different nanoparticles. Interestingly, the close homology of the silver resistance and copper resistance genes allowed for the biosensor to also be responsive to copper ions, implying that copper ions activate silver resistance. Further development of this biosensor could lead to commercial applications for environmental monitoring.ImportanceIonic silver is known to have many harmful environmental effects. Silver pollutants have been found in various environmental settings such as natural waterways and tailings from mining operations, raising concern. In addition, persistent exposure to silver in medical and environmental settings has led to the development of silver resistant bacteria, many of which are also resistant to a wide range of antibiotics. Some of these have the potential to develop into human pathogens. It then becomes important to have standardized methods for detecting and monitoring silver concentrations in various environments so that appropriate measures can be taken to prevent further silver ion release. This research shows that bacterial biosensors engineered to detect and quantify silver ions can be developed as effective alternatives to traditional analytical techniques. Further development of such biosensors could result in a commercial system for short and long term environmental monitoring, which is important as products containing silver and other heavy metals become increasingly popular.

scholarly journals Silver Ions as a Tool for Understanding Different Aspects of Copper Metabolism

Nutrients ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1364 ◽  
Author(s):  
Ludmila V. Puchkova ◽  
Massimo Broggini ◽  
Elena V. Polishchuk ◽  
Ekaterina Y. Ilyechova ◽  
Roman S. Polishchuk
Keyword(s):  
Active Sites ◽  
Large Scale ◽  
Copper Ions ◽  
Copper Metabolism ◽  
Silver Ions ◽  
The Body ◽  
Copper Binding ◽  
Safe Delivery ◽  
Protein Motifs ◽  
Wide Range

In humans, copper is an important micronutrient because it is a cofactor of ubiquitous and brain-specific cuproenzymes, as well as a secondary messenger. Failure of the mechanisms supporting copper balance leads to the development of neurodegenerative, oncological, and other severe disorders, whose treatment requires a detailed understanding of copper metabolism. In the body, bioavailable copper exists in two stable oxidation states, Cu(I) and Cu(II), both of which are highly toxic. The toxicity of copper ions is usually overcome by coordinating them with a wide range of ligands. These include the active cuproenzyme centers, copper-binding protein motifs to ensure the safe delivery of copper to its physiological location, and participants in the Cu(I) ↔ Cu(II) redox cycle, in which cellular copper is stored. The use of modern experimental approaches has allowed the overall picture of copper turnover in the cells and the organism to be clarified. However, many aspects of this process remain poorly understood. Some of them can be found out using abiogenic silver ions (Ag(I)), which are isoelectronic to Cu(I). This review covers the physicochemical principles of the ability of Ag(I) to substitute for copper ions in transport proteins and cuproenzyme active sites, the effectiveness of using Ag(I) to study copper routes in the cells and the body, and the limitations associated with Ag(I) remaining stable in only one oxidation state. The use of Ag(I) to restrict copper transport to tumors and the consequences of large-scale use of silver nanoparticles for human health are also discussed.

scholarly journals Polycationic Silver Nanoclusters Comprising Nanoreservoirs of Ag+-Ions with High Antimicrobial and Antibiofilm Activity

2021 ◽  
Author(s):  
Hanif Haidari ◽  
Richard Bright ◽  
Zlatko Kopecki ◽  
Peter Zilm ◽  
Sanjay Garg ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Bacterial Resistance ◽  
Anaerobic Bacteria ◽  
Silver Ions ◽  
Silver Nanoclusters ◽  
Antibiofilm Activity ◽  
Ion Release ◽  
Wide Range ◽  
Multiple Species ◽  
Conventional Antibiotics

Abstract The evolving resistance of bacteria to common antibiotics has prompted urgent demand for alternative antibacterial agents that not only control infections but are also able to prevent bacterial resistance. Silver-based nanoantibiotics are rapidly developing as promising alternatives because of their broad-spectrum antimicrobial activity, multifaceted mechanism of action and good biocompatibility. Ideally, to remain potent against a wide range of drug-resistant and anaerobic bacteria, silver-based nanoantibiotics should easily penetrate through the bacterial cell walls and actively release silver ions. However, most of the currently available silver nanomaterials are limited by their negative surface charge and the requirement of oxygen/water for the silver ion release. Here, a novel silver nanoparticle consisting of unique features including (i) ultra-small size (< 3 nm), (ii) high monodispersity, (iii) high percentage (> 50%) of silver ions content (i.e., Ag+- nanoreservoir) and (iv) polycationic surface layer was developed (referred as pAgNCs). The nanomaterial was very potent in eliminating a range of common Gram-negative and Gram-positive pathogens. Furthermore, the pAgNCs were also highly efficient in eradicating established and matured biofilms, including those composed of multiple species. The pAgNCs also showed greatly enhanced antibacterial efficacy against anaerobic bacteria such as F. nucleatum and S. sanguinis, which was attributed to the abundance of Ag+ ions in the nanoreservoir. Importantly, the pAgNCs showed a strong capacity to significantly delay the development of bacterial resistance when compared to similar-sized negatively charged AgNPs or conventional antibiotics. This study demonstrates a novel design strategy that can lay the foundation for the development of future highly potent nano-antibiotics effective against broad-spectrum of pathogens and biofilms needed in many everyday life applications and industries.

Controlling Silver Ion Release from Ag-Based Nanocoatings by Plasma Surface Engineering

2018 ◽  
Vol 941 ◽  
pp. 1625-1631 ◽  
Author(s):  
Linda Bonilla-Gameros ◽  
Maxime Cloutier ◽  
Vanessa Montaño-Machado ◽  
Pascale Chevallier ◽  
Diego Mantovani
Keyword(s):  
Surface Engineering ◽  
Silver Ions ◽  
Silver Ion ◽  
Ion Release ◽  
Plasma Surface ◽  
Antibacterial Coatings ◽  
Environmental Surfaces ◽  
Novel Strategy ◽  
Silver Release ◽  
Silver Ion Release

Environmental surfaces have been widely recognized as an important source of hospital-associated transmissions. A number of silver-based antibacterial coatings have been reported in the literature. However, the success of any antibacterial strategy depends on the ability to control the kinetics of the silver ions released from the coating. The novel strategy proposed in this work is based on plasma surface engineering for a controlled-release of silver ions. Plasma-based nanocoatings, plasma oxidation processes and surface patterning of silver coatings were designed and optimized. Surface analyses such as XPS and AFM, as well as silver ion release over 168 h, was evaluated by MIP-AES. Results showed that surface plasma engineering successfully allow tuning the silver release and bioactivity in Ag-containing antibacterial coatings.

scholarly journals Optimization of Silver Ion Release from Silver-Ceramic Porous Media for Household Level Water Purification

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 816 ◽  
Author(s):  
Rekha Singh ◽  
Chloe Rento ◽  
Veronica Son ◽  
Sydney Turner ◽  
James A. Smith
Keyword(s):  
Water Drop ◽  
Porous Ceramic ◽  
Silver Ions ◽  
Silver Ion ◽  
Bulk Solution ◽  
Ion Release ◽  
Silver Addition ◽  
Linear Effect ◽  
Silver Release ◽  
Silver Ion Release

A novel method has been developed to produce zerovalent silver nanopatches in a porous ceramic tablet using only clay, sawdust, water, and silver nitrate as precursors. When placed in 10 L of water, the silver nanopatches (2 to 3 nm diameter per patch) are gradually oxidized to produce silver ions, which diffuse out of the tablet into the bulk solution. The objective of this work is to optimize the silver-ceramic design to increase the rate of silver ion release from the tablet to further improve disinfection kinetics. To meet this objective, ceramic tablets were fabricated in different ways and tested for silver ion release into water over 8 to 24 h periods. Silver addition had an approximately linear effect on silver ion. Grinding the tablet into different particle sizes (4–60 mesh) had the most significant effect on silver release. However, if this ground fraction is compartmentalized into a fabric bag, silver levels produced in the water drop back to levels comparable to the single tablet form. Based on these results, 1 and 2 cm ceramic cubes were manufactured and represented a reasonable compromise between silver release and usability. Disinfection experiments on these silver-ceramic cubes resulted in effective disinfection of E. coli in laboratory experiments.

scholarly journals Effect of Silver Content on the Structure and Antibacterial Activity of Silver-Doped Phosphate-Based Glasses

2007 ◽  
Vol 51 (12) ◽  
pp. 4453-4461 ◽  
Author(s):  
Sabeel P. Valappil ◽  
David M. Pickup ◽  
Donna L. Carroll ◽  
Chris K. Hope ◽  
Jonathan Pratten ◽  
...  
Keyword(s):  
Glass Structure ◽  
Silver Ions ◽  
Structural Rearrangement ◽  
Bactericidal Effect ◽  
High Energy ◽  
Silver Ion ◽  
Ion Release ◽  
Bactericidal Agent ◽  
Silver Ion Release

ABSTRACT Staphylococcus aureus can cause a range of diseases, such as osteomyelitis, as well as colonize implanted medical devices. In most instances the organism forms biofilms that not only are resistant to the body's defense mechanisms but also display decreased susceptibilities to antibiotics. In the present study, we have examined the effect of increasing silver contents in phosphate-based glasses to prevent the formation of S. aureus biofilms. Silver was found to be an effective bactericidal agent against S. aureus biofilms, and the rate of silver ion release (0.42 to 1.22 μg·mm−2·h−1) from phosphate-based glass was found to account for the variation in its bactericidal effect. Analysis of biofilms by confocal microscopy indicated that they consisted of an upper layer of viable bacteria together with a layer (∼20 μm) of nonviable cells on the glass surface. Our results showed that regardless of the silver contents in these glasses (10, 15, or 20 mol%) the silver exists in its +1 oxidation state, which is known to be a highly effective bactericidal agent compared to that of silver in other oxidation states (+2 or +3). Analysis of the glasses by 31P nuclear magnetic resonance imaging and high-energy X-ray diffraction showed that it is the structural rearrangement of the phosphate network that is responsible for the variation in silver ion release and the associated bactericidal effectiveness. Thus, an understanding of the glass structure is important in interpreting the in vitro data and also has important clinical implications for the potential use of the phosphate-based glasses in orthopedic applications to deliver silver ions to combat S. aureus biofilm infections.

Application of TEM to Deformation, Wear, and Fracture of Ceramics

1974 ◽  
Vol 32 ◽  
pp. 472-473
Author(s):  
B. J. Hockey
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Mechanical Behavior ◽  
Brittle Materials ◽  
High Temperature Strength ◽  
Wide Range ◽  
Corrosive Environments ◽  
Further Development

Ceramics, such as Al2O3 and SiC have numerous current and potential uses in applications where high temperature strength, hardness, and wear resistance are required often in corrosive environments. These materials are, however, highly anisotropic and brittle, so that their mechanical behavior is often unpredictable. The further development of these materials will require a better understanding of the basic mechanisms controlling deformation, wear, and fracture.The purpose of this talk is to describe applications of TEM to the study of the deformation, wear, and fracture of Al2O3. Similar studies are currently being conducted on SiC and the techniques involved should be applicable to a wide range of hard, brittle materials.

To the 70th anniversary of World Meteorological Organization. Scientific and technical cooperation of Hydrometeorological Center of the USSR/Russia in the Programs of World Meteorological Organization

2020 ◽  
pp. 117-138
Author(s):  
S.V. Borshch ◽  
◽  
R.M. Vil’fand ◽  
D.B. Kiktev ◽  
V.M. Khan ◽  
...  
Keyword(s):  
Environmental Monitoring ◽  
High Efficiency ◽  
World Meteorological Organization ◽  
70Th Anniversary ◽  
Technical Level ◽  
Technical Cooperation ◽  
Wide Range

The paper presents the summary and results of long-term and multi-faceted experience of international scientific and technical cooperation of Hydrometeorological Center of Russia in the field of hydrometeorology and environmental monitoring within the framework of WMO programs, which indicates its high efficiency in performing a wide range of works at a high scientific and technical level. Keywords: World Meteorological Organization, major WMO programs, representatives of Hydrometeorological Center of Russia in WMO

scholarly journals Fractal diffusion of silver ions in hollow cylinders with unsmooth inner surface

2019 ◽  
Vol 14 ◽  
pp. 155892501989564
Author(s):  
Ling Lin ◽  
Shao-Wen Yao
Keyword(s):  
Fractal Dimension ◽  
Hollow Fiber ◽  
Theoretical Basis ◽  
Silver Ions ◽  
Present Theory ◽  
Ion Release ◽  
Practical Applications ◽  
Fractal Derivative ◽  
Inner Surface ◽  
Hollow Cylinders

This article studies the ion release from an unsmooth inner surface of a hollow fiber. A fractal diffusion model is established using the fractal derivative, and the effect of the fractal dimension on the ion release is elucidated. The present theory provides a theoretical basis for the optimization of a hollow fiber contained silver ions for practical applications.

scholarly journals A Putative Cro-Like Repressor Contributes to Arylomycin Resistance in Staphylococcus aureus

2015 ◽  
Vol 59 (6) ◽  
pp. 3066-3074 ◽  
Author(s):  
Arryn Craney ◽  
Floyd E. Romesberg
Keyword(s):  
Staphylococcus Aureus ◽  
Ex Vivo ◽  
Transcriptional Regulator ◽  
Signal Peptidase ◽  
Health Concern ◽  
Resistant Bacteria ◽  
Type I ◽  
Wall Teichoic Acid ◽  
Content Type ◽  
Wide Range

ABSTRACTAntibiotic-resistant bacteria are a significant public health concern and motivate efforts to develop new classes of antibiotics. One such class of antibiotics is the arylomycins, which target type I signal peptidase (SPase), the enzyme responsible for the release of secreted proteins from their N-terminal leader sequences. Despite the essentiality, conservation, and relative accessibility of SPase, the activity of the arylomycins is limited against some bacteria, including the important human pathogenStaphylococcus aureus. To understand the origins of the limited activity againstS. aureus, we characterized the susceptibility of a panel of strains to two arylomycin derivatives, arylomycin A-C16and its more potent analog arylomycin M131. We observed a wide range of susceptibilities to the two arylomycins and found that resistant strains were sensitized by cotreatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. To further understand howS. aureusresponds to the arylomycins, we profiled the transcriptional response ofS. aureusNCTC 8325 to growth-inhibitory concentrations of arylomycin M131 and found that it upregulates the cell wall stress stimulon (CWSS) and an operon consisting of a putative transcriptional regulator and three hypothetical proteins. Interestingly, we found that mutations in the putative transcriptional regulator are correlated with resistance, and selection for resistanceex vivodemonstrated that mutations in this gene are sufficient for resistance. The results begin to elucidate howS. aureuscopes with secretion stress and how it evolves resistance to the inhibition of SPase.

Effect of Silver Ions on the Structural and Antibacterial Properties of Bone Replacement Material

2013 ◽  
Vol 795 ◽  
pp. 692-696 ◽  
Author(s):  
Nida Iqbal ◽  
Mohammed Rafiq Abdul Kadir ◽  
Nasrul Humaimi Bin Mahmood ◽  
Micheal Moses ◽  
Mashitah Binti Mad Salim ◽  
...  
Keyword(s):  
Calcium Phosphates ◽  
Bacterial Species ◽  
Calcium Nitrate ◽  
Antibacterial Properties ◽  
Silver Ions ◽  
Antibacterial Activities ◽  
Silver Addition ◽  
Wide Range ◽  
Microbial Infections ◽  
Inorganic Mineral

Antibacterial materials based on calcium phosphates have wide range of biomedical applications in the prevention of microbial infections. The synthesis of inorganic mineral component of bone i.e. hydroxyapatite was done with the addition of silver (Ag) (5-15 wt %) as antibacterial agent. The wet precipitation synthesis was carried out using diammonium hydrogen phosphate and calcium nitrate as P and Ca precursors. The presence and effect of silver addition on the structure was studied using Fourier Transform-Infrared (FTIR) spectroscopy and Energy Dispersive X-ray (EDX) techniques. The antibacterial properties of all samples were evaluated using Disc Diffusion Technique (DDT) againstS. aureus,B. subtilis, P. aeruginosaandE. coli. Antibacterial activities of samples were found to vary depending on the bacterial species and Ag loading percentage. The antibacterial assay suggested that the addition of Ag ions within hydroxyapatite can be effectively provided the required level of antibacterial activity against bacteria.

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