An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core

Silver nanoparticles have antibacterial properties, but their use has been a cause for concern because they persist in the environment. Here, we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green alternative to silver nanoparticles. The polyelectrolyte layer promotes the adhesion of the particles to bacterial cell membranes and, together with silver ions, can kill a broad spectrum of bacteria, including Escherichia coli, Pseudomonas aeruginosa and quaternary-amine-resistant Ralstonia sp. Ion depletion studies have shown that the bioactivity of these nanoparticles is time-limited because of the desorption of silver ions. High-throughput bioactivity screening did not reveal increased toxicity of the particles when compared to an equivalent mass of metallic silver nanoparticles or silver nitrate solution. Our results demonstrate that the application of green chemistry principles may allow the synthesis of nanoparticles with biodegradable cores that have higher antimicrobial activity and smaller environmental impact than metallic silver nanoparticles

Ion-selective carbon-paste electrodes for halides and silver(I) ions

The behaviour of a simple type of ion-selective electrode for halogens and silver has been studied. The electrode consists of a plastic body filled with carbon paste, the surface of which can be easily renewed. The paste composition is based on carbon-nujol (5:1, w/v) or carbon-paraffin wax (3:1,w/w) containing a prepared mixture of silver halide-silver sulphide (1–30%). The electrodes have low ohmic resistance and show a rapid Nernstian response (within 2–5 mV) for halide and silver ions down to 5·10-5 M chloride, 1·10-5 M bromide and 5·10-7 M iodide with the respective electrodes. Ions forming very stable complexes with halide or silver and those having strong oxidizing or reducing action interfere

Silver as antibacterial toward Listeria monocytogenes

Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs) or silver nitrate (AgNO(3)). Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action

Elaboration and characterization of nanoplate structured alpha-Fe2O3 films by Ag3PO4

A new strategy for surface treatment of hematite nanoplates for efficient photoelectrochemical (PEC) performances is proposed. Silver orthophosphate (Ag₃PO₄) has been adopted to mediate the formation of α-Fe₂O₃ films. Phosphate ions in Ag₃PO₄ is found to cause a significant morphology change during annealing process, from β-FeOOH nanorod arrays to hematite nanoplates. Meanwhile, Ag ions is doped into α-Fe₂O₃ film. The obtained nanoplate structured Fe₂O₃ –Ag–P films demonstrate much higher photoelectrochemical performance as photoanodes than the bare Fe₂O₃ nanorod thin films. The effects of phosphate and silver ions on the morphology, surface characteristics and the PEC properties of the photoanodes are investigated

Citrate and Polyvinylpyrrolidone Stabilized Silver Nanoparticles as Selective Colorimetric Sensor for Aluminum (III) Ions in Real Water Samples

The use of silver nanoparticles stabilized with citrate and polyvinylpyrrolidone as a sensor for aluminum ions determination is proposed in this paper. These non-functionalized and specific nanoparticles provide a highly selective and sensitive detection system for aluminum in acidic solutions. The synthesized nanoparticles were characterized by transmission electron microscopy. Surface plasmon band deconvolution analysis was applied to study the interaction between silver nanoparticles and aluminum ions in solution. The interaction band in the UV-visible region was used as an analytical signal for quantitation purposes. The proposed detection system offers an effective AND wide linearity range (0.1-103 nM), specificity for Al(III) in THE presence of other metallic ions in solution, as well as high sensitivity (limit of detection = 40.5 nM). The proposed silver-nanoparticles-based sensor WAS successfully used for detecting Al(III) in real water samples.Spanish Ministerio de Economía y Competitividad, MinECo, CTQ2016-78703-P (AEI/FEDER, UE)España, Universidad de Sevilla ,V Plan Propio Grupos Emergentes (PP2016-5937)Junta de Andalucía (2017/FQM-386)CITIUS VI PP USO SSGG (1804031606

Water management system and an electrolytic cell therefor Patent

Description of electrical equipment and system for purification of waste water by producing silver ions for bacterial contro

Inactivation of the antibacterial and cytotoxic properties of silver ions by biologically relevant compounds

There has been a recent surge in the use of silver as an antimicrobial agent in a wide range of domestic and clinical products, intended to prevent or treat bacterial infections and reduce bacterial colonization of surfaces. It has been reported that the antibacterial and cytotoxic properties of silver are affected by the assay conditions, particularly the type of growth media used in vitro. The toxicity of Ag+ to bacterial cells is comparable to that of human cells. We demonstrate that biologically relevant compounds such as glutathione, cysteine and human blood components significantly reduce the toxicity of silver ions to clinically relevant pathogenic bacteria and primary human dermal fibroblasts (skin cells). Bacteria are able to grow normally in the presence of silver nitrate at >20-fold the minimum inhibitory concentration (MIC) if Ag+ and thiols are added in a 1:1 ratio because the reaction of Ag+ with extracellular thiols prevents silver ions from interacting with cells. Extracellular thiols and human serum also significantly reduce the antimicrobial activity of silver wound dressings Aquacel-Ag (Convatec) and Acticoat (Smith & Nephew) to Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli in vitro. These results have important implications for the deployment of silver as an antimicrobial agent in environments exposed to biological tissue or secretions. Significant amounts of money and effort have been directed at the development of silver-coated medical devices (e.g. dressings, catheters, implants). We believe our findings are essential for the effective design and testing of antimicrobial silver coatings

Silver-based Microbial Check Valve for Spacecraft Potable Water Systems

As human space exploration increases, the development of a more efficient potable water treatment system suited for spacecraft becomes crucial. This Waste-management Education Research Consortium (WERC) challenge was designed to explore the viability of microbial control through the utilization of silver ions as a biocide for possible integration into the Tranquility Node 3 water purification system aboard the International Space Station (ISS). Current systems using iodine risk causing hyperthyroidism from overexposure; however, silver can be safely ingested without this side effect. After researching silver delivery methods including electrochemical ion production, controlled release, or a combination of the two, our team decided to design a controlled release system capable of meeting the constraints listed in the problem statement. By using a membrane similar to those within dialysis devices a system was designed to deliver silver ions to a stream of water that requires arguably no power and is exceptionally lightweight. While the silver delivery system fulfilled the constraints of the WERC problem statement, our team also examined the use of resins like those contained in the current Microbial Check Valve (MCV). Resin substitutes capable of selective silver sorption are recommended as replacements for those within the current MCV to prevent backwards microbial diffusion through the system. Multiple designs will be presented in this paper. First, our membrane-controlled release silver delivery system (SDS) is presented to specifically address the WERC Task 1 deliverables. Second, a proposed upgrade to the ISS water system is described that replaces the ion exchange resin beds with silver-selective media prevent microbial contamination of water in the potable water system of the spacecraft. Given the extreme lightweight nature of the SDS, nil power requirement, and minor modification to the existing system, Hogs In Space has delivered a highly effective method to deliver and control silver based on the WERC Task 1 requirements

Biocidal effects of silver Final technical report

Elimination of microbial and viral agents from spacecraft water systems by silver ions from electrolytic ion generato