Promoting Effect of Silver Oxide Nanoparticles on the Oxidation of Bisphenol B by Ferrate(VI)

Bisphenol B (BPB, 2,2-bis(4-hydroxyphenyl) butane), as a substitute for bisphenol A, has been widely detected in the environment and become a potential threat to environmental health. This work found that silver oxide nanoparticles (Ag2O) could greatly promote the removal of BPB by ferrate (Fe(VI)). With the presence of 463 mg/L Ag2O, the amount of Fe(VI) required for the complete removal of 10 μM BPB will be reduced by 70%. Meanwhile, the recyclability and stability of Ag2O have been verified by recycling experiments. The characterization results and in situ electrochemical analyses showed that Ag(II) was produced from Ag(I) in the Fe(VI)-Ag2O system, which has a higher electrode potential to oxidize BPB to enhance its removal. A total of 13 intermediates were identified by high-resolution mass spectrometry, and three main reaction pathways were proposed, including oxygen transfer, bond breaking, and polymerization. Based on the toxicity assessment through the ECOSAR program, it is considered that the presence of Ag2O reduced the toxicity of BPB oxidation intermediates to aquatic organisms. These results would deepen our understanding of the interaction between Fe(VI) and Ag2O, which may provide an efficient and environmentally friendly method for water and wastewater treatment.

Development of Ag-ZnO/AgO Nanocomposites Effectives for Leishmania braziliensis Treatment

Tegumentary leishmaniasis (TL) is caused by parasites of the genus Leishmania. Leishmania braziliensis (L.b) is one of the most clinically relevant pathogens that affects the skin and mucosa, causing single or multiple disfiguring and life-threatening injuries. Even so, the few treatment options for patients have significant toxicity, high dropout rates, high cost, and the emergence of resistant strains, which implies the need for studies to promote new and better treatments to combat the disease. Zinc oxide nanocrystals are microbicidal and immunomodulatory agents. Here, we develop new Ag-ZnO/xAgO nanocomposites (NCPs) with three different percentages of silver oxide (AgO) nanocrystals (x = 49%, 65%, and 68%) that could act as an option for tegumentary leishmaniasis treatment. Our findings showed that 65% and 68% of AgO inhibit the extra and intracellular replication of L.b. and present a high selectivity index. Ag-ZnO/65%AgO NCPs modulate activation, expression of surface receptors, and cytokine production by human peripheral blood mononuclear cells toward a proinflammatory phenotype. These results point to new Ag-ZnO/AgO nanocomposites as a promising option for L. braziliensis treatment.

Ag2O Nanoparticles as a Candidate for Antimicrobial Compounds of the New Generation

Antibiotic resistance in microorganisms is an important problem of modern medicine which can be solved by searching for antimicrobial preparations of the new generation. Nanoparticles (NPs) of metals and their oxides are the most promising candidates for the role of such preparations. In the last few years, the number of studies devoted to the antimicrobial properties of silver oxide NPs have been actively growing. Although the total number of such studies is still not very high, it is quickly increasing. Advantages of silver oxide NPs are the relative easiness of production, low cost, high antibacterial and antifungal activities and low cytotoxicity to eukaryotic cells. This review intends to provide readers with the latest information about the antimicrobial properties of silver oxide NPs: sensitive organisms, mechanisms of action on microorganisms and further prospects for improving the antimicrobial properties.

Transparent Anti-SARS-CoV-2 and Antibacterial Silver Oxide Coatings

Transparent antimicrobial coatings can maintain the aesthetic appeal of surfaces and the functionality of a touch-screen while adding the benefit of reducing disease transmission. We fabricated an antimicrobial coating of silver oxide particles in a silicate matrix on glass. The matrix was grown by a modified Stöber sol-gel process with vapor-phase water and ammonia. A coating on glass with 2.4 mg of Ag2O per mm2 caused a reduction of 99.3% of SARS-CoV-2 and >99.5% of Pseudomonas aeruginosa, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus compared to the uncoated glass after 1 h. We envisage that screen protectors with transparent antimicrobial coatings will find particular application to communal touch-screens, such as in supermarkets and other check-out or check-in facilities where a number of individuals utilize the same touch-screen in a short interval.

Synthesis of a Novel, Biocompatible and Bacteriostatic Borosiloxane Composition with Silver Oxide Nanoparticles

Microbial antibiotic resistance is an important global world health problem. Recently, an interest in nanoparticles (NPs) of silver oxides as compounds with antibacterial potential has significantly increased. From a practical point of view, composites of silver oxide NPs and biocompatible material are of interest. A borosiloxane (BS) can be used as one such material. A composite material combining BS and silver oxide NPs has been synthesized. Composites containing BS have adjustable viscoelastic properties. The silver oxide NPs synthesized by laser ablation have a size of ~65 nm (half-width 60 nm) and an elemental composition of Ag₂O. The synthesized material exhibits strong bacteriostatic properties against E. coli at a concentration of nanoparticles of silver oxide more than 0.01%. The bacteriostatic effect depends on the silver oxide NPs concentration in the matrix. The BS/silver oxide NPs have no cytotoxic effect on a eukaryotic cell culture when the concentration of nanoparticles of silver oxide is less than 0.1%. The use of the resulting composite based on BS and silver oxide NPs as a reusable dry disinfectant is due to its low toxicity and bacteriostatic activity and its characteristics are not inferior to the medical alloy nitinol.

Application of ZnO Nanocrystals as a Surface-Enhancer FTIR for Glyphosate Detection

Glyphosate detection and quantification is still a challenge. After an extensive review of the literature, we observed that Fourier transform infrared spectroscopy (FTIR) had practically not yet been used for detection or quantification. The interaction between zinc oxide (ZnO), silver oxide (Ag₂O), and Ag-doped ZnO nanocrystals (NCs), as well as that between nanocomposite (Ag-doped ZnO/AgO) and glyphosate was analyzed with FTIR to determine whether nanomaterials could be used as signal enhancers for glyphosates. The results were further supported with the use of atomic force microscopy (AFM) imaging. The glyphosate commercial solutions were intensified 10,000 times when incorporated the ZnO NCs. However, strong chemical interactions between Ag and glyphosate may suppress signaling, making FTIR identification difficult. In short, we have shown for the first time that ZnO NCs are exciting tools with the potential to be used as signal amplifiers of glyphosate, the use of which may be explored in terms of the detection of other molecules based on nanocrystal affinity.

Controlled Growth of Silver Oxide Nanoparticles on the Surface of Citrate Anion Intercalated Layered Double Hydroxide

Silver oxide nanoparticles with controlled particle size were successfully obtained utilizing citrate-intercalated layered double hydroxide (LDH) as a substrate and Ag+ as a precursor. The lattice of LDH was partially dissolved during the reaction by Ag+. The released hydroxyl and citrate acted as a reactant in crystal growth and a size controlling capping agent, respectively. X-ray diffraction, X-ray photoelectron spectroscopy, and microscopic measurements clearly showed the development of nano-sized silver oxide particles on the LDH surface. The particle size, homogeneity and purity of silver oxide were influenced by the stoichiometric ratio of Ag/Al. At the lowest silver ratio, the particle size was the smallest, while the chemical purity was the highest. X-ray photoelectron spectroscopy and UV-vis spectroscopy results suggested that the high Ag/Al ratio tended to produce silver oxide with a complex silver environment. The small particle size and homogeneous distribution of silver oxide showed advantages in antibacterial efficacy compared with bulk silver oxide. LDH with an appropriate ratio could be utilized as a substrate to grow silver oxide nanoparticles with controlled size with effective antibacterial performance.

A Highly Efficient Glycosidation of Glycosyl Chlorides by Using Cooperative Silver(I) Oxide-Triflic Acid Catalysis

Following our discovery that silver(I) oxide-promoted glycosylation with glycosyl bromides can be greatly accelerated in the presence of catalytic TMSOTf or TfOH, we report herein a new discovery that glycosyl chlorides are even more effective glycosyl donors under these reaction conditions. The developed reaction conditions work well with a variety of glycosyl chlorides. Both benzoylated and benzylated chlorides have been successfully glycosidated, and these reaction conditions proved to be effective in coupling substrates containing nitrogen and sulfur atoms. Another convenient feature of this glycosylation is that the progress of the reaction can be monitored visually; its completion can be judged by the disappearance of the characteristic dark color of Ag₂ O.

Surface Interactions and Mechanisms Study on the Removal of Iodide from Water by Use of Natural Zeolite-Based Silver Nanocomposites

In this work a natural zeolite was modified with silver following two different methods to derive Ag2O and Ag0 nanocomposites. The materials were fully characterized and the results showed that both materials were decorated with nanoparticles of size of 5-25 nm. The natural and modified zeolites were used for the removal of iodide from aqueous solutions of initial concentration of 30-1400 ppm. Natural zeolite showed no affinity for iodide while silver forms were very efficient reaching a capacity of up to 132 mg/g. Post-adsorption characterizations showed that AgI was formed on the surface of the modified zeolites and the amount of iodide removed was higher than expected based on the silver content. A combination of experimental data and characterizations indicate that the excess iodide is most probably related to negatively charged AgI colloids and Ag-I complexes forming in the solution as well as on the surface of the modified zeolites.

Formation of Silver Rhombic Dodecahedra, Octahedra, and Cubes through Pseudomorphic Conversion of Ag2O Crystals with Nitroarene Reduction Activity

Using ethanol as a co-solvent, relatively small-sized Ag₂O octahedra (∼645 nm in opposite corner distance) and rhombic dodecahedra (∼540 and 655 nm in opposite face distance) were synthesized in aqueous solutions. Ag₂O cubes synthesized in an aqueous solution have an edge length of ∼425 nm. Band gaps of these crystals have been obtained, revealing the presence of facet-dependent light absorption properties. The Ag₂O rhombic dodecahedra, octahedra, and cubes were treated with ammonia borane in ethanol at 50 °C for just 10 min to pseudomorphically convert to Ag polyhedra of the corresponding morphologies. Transmission electron microscopy characterization confirms that the Ag cubes, octahedra, and rhombic dodecahedra are bound by the {100}, {111}, and {110} faces, respectively. The Ag rhombic dodecahedra, available for the first time, showed more superior catalytic activity toward 4-nitroaniline reduction at 50 °C than Ag octahedra and cubes, and gave 100% product yield after 1 h of reaction. This work demonstrates the value of forming Ag rhombic dodecahedra, exposing {110} surfaces that may be useful in other organic transformations.

Deliberately Designed Atomic-Level Silver-Containing Interface Results in Improved Rate Capability and Utilization of Silver Hollandite for Lithium-Ion Storage

α-MnO₂-structured materials are generally classified as semiconductors; thus, we present a strategy to increase electrochemical utilization through the design of a conductive material interface. Surface treatment of silver hollandite (Ag_xMn₈O₁₆) with Ag⁺ (Ag₂O) provides significant benefits to the resultant electrochemistry, including a decreased charge-transfer resistance and a 2-fold increase in deliverable energy density at a high rate. The improved function of this designed interface relative to conventional electrode fabrication strategies is highlighted.

Facile chemical routes to mesoporous silver substrates for SERS analysis

Mesoporous silver nanoparticles were easily synthesized through the bulk reduction of crystalline silver(I) oxide and used for the preparation of highly porous surface-enhanced Raman scattering (SERS)-active substrates. An analogous procedure was successfully performed for the production of mesoporous silver films by chemical reduction of oxidized silver films. The sponge-like silver blocks with high surface area and the in-situ-prepared mesoporous silver films are efficient as both analyte adsorbents and Raman signal enhancement mediators. The efficiency of silver reduction was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The developed substrates were applied for SERS detection of rhodamine 6G (enhancement factor of about 1-5 × 10⁵) and an anti-ischemic mildronate drug (meldonium; enhancement factor of ≈10²) that is known for its ability to increase the endurance performance of athletes.

Silver Oxide Coatings with High Silver-Ion Elution Rates and Characterization of Bactericidal Activity

This paper reports the synthesis and characterization of silver oxide films for use as bactericidal coatings. Synthesis parameters, dissolution/elution rate, and bactericidal efficacy are reported. Synthesis conditions were developed to create AgO, Ag₂O, or mixtures of AgO and Ag₂O on surfaces by reactive magnetron sputtering. The coatings demonstrate strong adhesion to many substrate materials and impede the growth of all bacterial strains tested. The coatings are effective in killing Escherichia coli and Staphylococcus aureus, demonstrating a clear zone-of-inhibition against bacteria growing on solid media and the ability to rapidly inhibit bacterial growth in planktonic culture. Additionally, the coatings exhibit very high elution of silver ions under conditions that mimic dynamic fluid flow ranging between 0.003 and 0.07 ppm/min depending on the media conditions. The elution of silver ions from the AgO/Ag₂O surfaces was directly impacted by the complexity of the elution media, with a reduction in elution rate when examined in complex cell culture media. Both E. coli and S. aureus were shown to bind ~1 ppm Ag⁺/mL culture. The elution of Ag⁺ resulted in no increases in mammalian cell apoptosis after 24 h exposure compared to control, but apoptotic cells increased to ~35% by 48 and 72 h of exposure. Taken together, the AgO/Ag₂O coatings described are effective in eliciting antibacterial activity and have potential for application on a wide variety of surfaces and devices.

Photoelectrochemical Performance of the Ag(III)-Based Oxygen-Evolving Catalyst

We report the electrosynthesis of a water oxidation catalyst based on Ag oxides (AgCat). The deposited AgCat is composed of mixed valence crystalline Ag oxides with the presence of particle aggregates whose size is ∼1 μm. This catalyst, coupled with TiO₂ and hematite, and under photoelectrochemical conditions, substantially increases photocurrents in a wide range of applied potentials compared with bare and Co-Pi-modified photocatalysts. AgCat can sustain current densities comparable with other water oxidation catalysts. Dark bulk electrolysis demonstrated that AgCat is stable and can sustain high turnover number in operative conditions. Oxygen evolution from water occurs in mild conditions: pH = 2-13, room temperature and pressure, and moderate overpotentials (600 mV) compatible with the coupling with semiconducting oxides as sensitizers. Using hematite in sustained electrolysis O₂ production is significant, both in the dark and under irradiation, after an initial slow induction time in which modification of surface species occurs.

Synthesis of Diverse Ag2O Crystals and Their Facet-Dependent Photocatalytic Activity Examination

Sub- to micrometer-sized Ag2O cubes, great rhombicuboctahedra, cuboctahedra, corner-truncated octahedra, octahedra, and rhombic dodecahedra have been synthesized at room temperature using simple molar ratios of NH4NO3, NaOH, and AgNO3 solutions with a short reaction time. In addition, tuning the concentration of NH3 in the solution can provide more particle morphologies including edge- and corner-truncated cubes, small rhombicuboctahedra, and edge-truncated octahedra to enrich Ag2O shape diversity. X-ray photoelectron spectroscopy (XPS) spectra indicate surface composition of various crystals as pure Ag2O. Diffuse reflectance spectra have been used to determine the band gap of Ag2O cubes. Ag2O cubes, octahedra, and rhombic dodecahedra having the same total particle surface area were used for facet-dependent photocatalytic activity comparison in the degradation of methyl orange. Cubes are comparably highly active for this reaction, while octahedra and rhombic dodecahedra give moderate and low catalytic activities, respectively. Electron paramagnetic resonance (EPR) measurements confirm this reactivity order. Although all Ag2O samples show significant etching during photocatalysis, metallic silver is not produced.

Dielectric Barrier Discharge (DBD) Plasma Assisted Synthesis of Ag₂O Nanomaterials and Ag₂O/RuO₂ Nanocomposites

Silver oxide, ruthenium oxide nanomaterials and its composites are widely used in a variety of applications. Plasma-mediated synthesis is one of the emerging technologies to prepare nanomaterials with desired physicochemical properties. In this study, dielectric barrier discharge (DBD) plasma was used to synthesize Ag₂O and Ag₂O/RuO₂ nanocomposite materials. The prepared materials showed good crystallinity. The surface morphology of the Ag₂O exhibited “garland-like” features, and it changed to “flower-like” and “leaf-like” at different NaOH concentrations. The Ag₂O/RuO₂ composite showed mixed structures of aggregated Ag₂O and sheet-like RuO₂. Mechanisms governing the material’s growth under atmospheric pressure plasma were proposed. Chemical analysis was performed using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) showed the thermal decomposition behavior and the oxygen release pattern.

Silver Oxide Based Nanoparticle Assisted Laser Desorption/Ionization Mass Spectrometry for the Detection of Low Molecular Weight Compounds

A specific property of silver oxide-based nanoparticles permits the ionization of an analyte, giving rise to various applications of a smart analytical methodology. The nanoparticles (d=6.7 nm) contained an Ag2O core. The detection of several model componds (a nucleobase and two hair growth promoters) via the use of silver oxide nanoparticles is described. Adducts were produced between the target molecules and the two silver stable isotopes (Ag(107) and Ag(109)), resulting in the formation of specific signals as well as a protonated signal. Thus, it was possible to easily determine whether the given signals were correlated with the target molecule or not.

Plasmonic ZnO/Ag embedded structures as collecting layers for photogenerating electrons in solar hydrogen generation photoelectrodes

A new fabrication strategy in which Ag plasmonics are embedded in the interface between ZnO nanorods and a conducting substrate is experimentally demonstrated using a femtosecond-laser (fs-laser)-induced plasmonic ZnO/Ag photoelectrodes. This fs-laser fabrication technique can be applied to generate patternable plasmonic nanostructures for improving their effectiveness in hydrogen generation. Plasmonic ZnO/Ag nanostructure photoelectrodes show an increase in the photocurrent of a ZnO nanorod photoelectrodes by higher than 85% at 0.5 V. Both localized surface plasmon resonance in metal nanoparticles and plasmon polaritons propagating at the metal/semiconductor interface are available for improving the capture of sunlight and collecting charge carriers. Furthermore, in-situ X-ray absorption spectroscopy is performed to monitor the plasmonic-generating electromagnetic field upon the interface between ZnO/Ag nanostructures. This can reveal induced vacancies on the conduction band of ZnO, which allow effective separation of charge carriers and improves the efficiency of hydrogen generation. Plasmon-induced effects enhance the photoresponse simultaneously, by improving optical absorbance and facilitating the separation of charge carriers.

Silver-mediated fluorination of aryl silanes

A regiospecific silver-mediated fluorination of aryl silanes is reported. The reaction is operationally simple, and employs Ag(2)O as readily available, inexpensive silver source, which can be recovered.

Model free approach for non-isothermal decomposition of un-irradiated and γ-irradiated silver acetate: new route for synthesis of Ag(2)O nanoparticles

Kinetic studies for the non-isothermal decomposition of unirradiated and γ-irradiated silver acetate with 10(3) kGy total γ-ray doses were carried out in air. The results showed that the decomposition proceeds in one major step in the temperature range of (180-270 °C) with the formation of Ag(2)O as solid residue. The non-isothermal data for un-irradiated and γ-irradiated silver acetate were analyzed using Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ) iso-conversional methods. These free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes in the thermal decomposition behavior of silver acetate were recorded as a result of γ-irradiation. Calcinations of γ-irradiated silver acetate (CH(3)COOAg) at 200 °C for 2 hours only led to the formation of pure Ag(2)O mono-dispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesized nanoparticles.