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This study presents a novel approach for regulating the properties of lignin‐based silver nanoparticles (AgNPs), which was UV‐induced Tetrahydrofuran (THF) to form peroxide for the etching of these nanoparticles. The lignin coating was first degraded by oxidation, and the properties of the exposed AgNPs changed under etching. Notably, water can greatly regulate the oxidation capacity of the THF medium, thereby controlling the degradation degree of lignin coating and obtaining dissolution, aggregation, precipitation, and color‐variable phenomena of AgNPs under the synergistic effect of UV irradiation and peroxide etching. By adjusting UV irradiation time, various functional products of silver nanowires (AgNWs), color‐variable AgNPs, lignin‐based AgNPs aggregates, and composite solution of Ag particles and Ag+ were obtained. The transformation of these product properties is closely related to the oxidation capacity of H2O/THF medium. In addition, Multi‐functional Lignin‐based AgNPs show excellent application potential in conductive coating, antibacterial enhancement, and product separation, providing a promising avenue for the targeted utilization of lignin‐based AgNPs. [ABSTRACT FROM AUTHOR]

The present work shows the synthesis of Ag nanoparticles in a two-phase system (organic/aqueous), in which the amphiphilic properties of naphthenic acid are used for the formation of reverse micelles that act as micro reactors. Therefore, the appropriate energy conditions are given for the precipitation of metallic Ag nanoparticles, using AgNO3 as a precursor. Likewise, the effect of the synthesis reaction time was studied to know its relationship with the final morphology of the material. X-Ray Diffraction and Scanning Electron Microscopy, coupled with Energy Dispersive Spectroscopy, were used to characterize the solids. The results show that in the Ag+-Ag° reduction reaction carried out at t = 1.5 h and T = 200 °C, metallic silver nanoparticles precipitate of FCC structure, with homogeneous globular morphology and average diameter of 50 nm. By prolonging the residence time of the system at 200 °C (artificial aging), the material undergoes a series of transformations both in size and morphology, causing partial oxidation of the silver. At TEA of 0.5 h, the particles grow without evident structural change; by increasing TEA to 1 h, the transformation in solid state is observed, obtaining a mixture of phases, AgO, Ag3O4 and Ag2O, coming from the partial oxidation of silver, with monoclinic and hexagonal structures and the dimensions nano and micrometric. Finally, increasing the aging time to 1.5 h only causes an increase in particle size, without modification in the structures obtained at shorter times. [ABSTRACT FROM AUTHOR]

Combining the Hg2+-induced oxidization of silver nanoparticles with the cation exchange reaction between Ag+ and CuS nanoparticles for cascade signal amplification, a sensitive, universal and label-free ICP-MS bioassay for nucleic acids and proteins was developed. By replacing the loop sequence of the T–Hg–T hairpin structure with specific sequences or aptamers to different biomarkers, it has great promise for the early detection of biomarkers potentially for diagnosis of cancerous diseases. [ABSTRACT FROM AUTHOR]

The colorimetric detection of dopamine was investigated to enhance the dopamine detection sensitivity. The detection was through the oxidation of AgNPs by hydrogen peroxide converted from dopamine along with dihydroxyphenylacetaldehyde. The conversion was facilitated by monoamine oxidase-Bs (MAO-Bs) bound to biomimetic membranes. The absorbance at 410 nm decreased with the increase in dopamine concentration. The limit of detection was determined to be 0.013 μM for 0.01 to 3.5 μM dopamine in the linear range of absorbance. The absorbance change corresponded to the conversion of Ag to Ag2O, which occurred with the hydrogen peroxide released through MAO-Bs from dopamine. These results indicate that the AgNP degradation based on the immobilized MAO-Bs is sufficiently appropriate for the high-sensitivity absorbance detection of dopamine with a wide linear range. [ABSTRACT FROM AUTHOR]

Epithelial integrity and function must be maintained in a dynamic healthy equilibrium, keeping unaltered the oxidative and inflammatory conditions and the microbiome of the cutaneous layers. Beside the skin, other mucous membranes can be injured, such as the nasal and anal ones, because of the contact with the external environment. Here, we detected the effects of RIPACUT®, a combination of Iceland lichen extract, silver salt and sodium hyaluronate that individually act in diverse biological ways. The findings we obtained on keratinocytes, nasal and intestinal epithelial cells reveal that this combination showed a marked antioxidant activity, further assessed by the DPPH assay. Additionally, by analyzing the release of the IL-1β, TNF-α and IL-6 cytokines, we proved the anti-inflammatory effect of RIPACUT®. In both cases, the main preserving action was due to Iceland lichen. We also observed a notable antimicrobial activity mediated by the silver compound. These data suggest that RIPACUT® could signify the basis for an attractive pharmacological approach to maintaining healthy epithelial conditions. Interestingly, this may be extended to the nasal and anal areas where it protects against oxidative, inflammatory and infectious insults. Thus, these outcomes encourage the creation of sprays or creams for which sodium hyaluronate can guarantee a surface film-forming effect. [ABSTRACT FROM AUTHOR]

The water oxidation of bimetallic Al/Ag nanoparticles has been shown to yield nanoscale structures whose morphology, phase composition and textural characteristics are determined by the synthesis conditions. Flower-like nanoscale structures with silver nanoparticles, with an average size of 17 nm, are formed in water at 60 °C. Under hydrothermal conditions at temperatures of 200 °C and a pressure of 16 MPa, boehmite nanoplatelets with silver nanoparticles, with an average size of 22 nm, are formed. The oxidation of Al/Ag nanoparticles using humid air at 60 °C and 80% relative humidity results in the formation of rod-shaped bayerite nanoparticles and Ag nanoparticles with an average size of 19 nm. The thermal treatment of nanoscale structures obtained at a temperature of 500 °C has been shown to lead to a phase transition into γ-Al2O3, while maintaining the original morphology, and to a decrease in the average size of the silver nanoparticles to 12 nm and their migration to the surface of nanoscale structures. The migration of silver to the nanoparticle surface influences the formation of a double electric layer of particles, and leads to a shift in the pH of the zero-charge point by approximately one, with the nanostructures acquiring pronounced antimicrobial properties. [ABSTRACT FROM AUTHOR]

Herein, we present a facile and convenient method for the preparation of silver nanoparticles (AgNPs) in the presence of quercetagetin, a unique plant flavonoid, as a reducing and stabilizing agent. The nanoparticles (Que-AgNPs) were characterized using UV–vis spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and dynamic light scattering techniques. Que-AgNPs display a spherical shape and a crystalline structure. The size of Que-AgNPs was calculated to be 93 ± 0.4 nm in diameter with polydispersity index value of 0.3. Que-AgNPs were evaluated as nanocatalysts in the oxidative degradation of morin with hydrogen peroxide (H2O2). The catalytic degradation of morin was completed within 20 min, demonstrating excellent catalytic properties for Que-AgNPs. Kinetic studies revealed that the reaction follows pseudo-first-order kinetics and the apparent rate constant (kapp) is positively correlated with the concentration of Que-AgNPs; however, kapp is inversely associated with the morin concentration. Moreover, the cytotoxicity of Que-AgNPs was evaluated by the cell viability test considering two cell lines, i.e., HeLa and MCF-7. The results show that Que-AgNPs possess dose-dependent cytotoxic activity. [ABSTRACT FROM AUTHOR]

In this paper, the Ti6Al4V alloy surface was modified via ceramic conversion treatment (CCT) with or without a pre-deposited silver layer. After characterizing the surface morphologies, microstructure and phase constituents of the ceramic oxide layer formed at 620 °C, we investigated the surface hardness and the cross-sectional nano-hardness profile under the oxide layer. The static load-bearing capacity of the oxide layers was examined by applying discrete loads via a Vickers indenter and observing the indentations. A scratch test was used to evaluate the load-bearing capacity and the adhesion/cohesion of the oxide layers. The wettability of the surface changed due to the incorporation of silver and the change of surface morphology. Reciprocating friction and wear test was used to assess the tribological properties. Small and dispersed silver nanoparticles and clusters were found in the oxide layer of the Ag pre-deposited Ti6Al4V samples, and they had much better tribological properties in terms of reduced coefficient of friction and wear volume. With the assistance of silver, the efficiency of the CCT was significantly improved. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu/ZSM-5 core enveloped by S-1 shell with confined Ag0 nanoparticles. • Core-shell architecture fosters the generation of abundant active Ag0 nanoparticles. • Silicalite-1 shell hinders Ag0 migration and preserves active Cu2+ sites. • Discretely distributed Cu2+ and Ag0 centers underpin a catalytically robust system. • Cu/ZSM-5@Ag/S-1 exhibits superior hydrothermal stability and NH 3 -SCO activity. A judiciously devised core–shell NH 3 -SCO catalyst featuring a Cu/ZSM-5 core enveloped by an Ag/silicalite-1 shell (Cu/ZSM-5@Ag/S-1) was rationally constructed. Integrating the silicalite-1 shell effectively suppresses the migration of Ag into Cu/ZSM-5 core, conserving the active Cu2+ sites for the catalytical conversion of byproducts NO x. Concurrently, the shell averts the formation of positively charged Ag species, facilitating the generation of abundant Ag0 nanoparticles encapsulated in the S-1 shell. Comprehensive characterizations reveal abundant Ag0 species within the core–shell Cu/ZSM-5@Ag/S-1 catalyst, boosting O 2 activation and NH 3 dehydrogenation and thereby contributing to superior low-temperature activity in NH 3 -SCO reactions. Furthermore, the hydrophobic S-1 shell effectively reinforces the hydrothermal stability of the core–shell Cu/ZSM-5@Ag/S-1. DRIFTS coupled with DFT studies elucidate that the core–shell sample follows the imide mechanism, while the shell-free sample adheres to the hydrazine mechanism. This work advances our understanding of catalyst design and presents a promising solution with practical implications for ammonia oxidation processes. [ABSTRACT FROM AUTHOR]

Straight silver nanowires were synthesized by accelerated oxidization and then aligned into ordered arrays by off-center spin-coating. Seesaw-like behavior was observed in the polarized transmission spectra of the arrays. With the increment of polarization angle (θP, defined as the angle between axis of nanowires and direction of electric field of light), transmission changed repeatedly with a period of 180°, but it moved to opposite directions between the two regions separated by supporting points locating at 494 nm. The behavior is ascribed to the competition between the extinction behaviors of the two modes of surface plasma polaritons on silver nanowires. One is the longitudinal mode which is excited by long wavelengths and tuned by function of cos2( θ p ) and the other is the transverse mode that is excited by short wavelengths and tuned by function of sin2( θ p ). Simulation was performed based on the finite-difference time domain method. The effect of the nanowire diameter and length (aspect ratio) on the position of the supporting point was studied. As nanowire width increased from 20 nm to 350 nm, the supporting point moved from 400 to 500 nm. While it changed slightly when the nanowire length increased from 3 μm to infinitely long (width fixed at 260 nm). In current study, the position of the supporting point is mainly determined by the nanowire width. [ABSTRACT FROM AUTHOR]

Methods for preparing stable colloidal solutions containing bimetallic copper–silver nanoparticles via reduction due to the difference of oxidation potentials of the pairs Ag+/Ag0 and Cu2+/Cu0 and via synthesis in polymeric materials, namely polyamide and viscose fabrics and cellophane and polyamide films, are discussed. [ABSTRACT FROM AUTHOR]

In this work, we obtained silver nanoparticles stabilized with polyvinylpyrrolidone, ranging in size from 70 to 110 nm, which exhibits good crystallinity and anisotropic structure. For the first time, we studied the influence of the molar ratio of silver between silver and peroxide on the oxidation process of the nanoparticles and determined the regularities of this process by analyzing changes in absorption spectra. Our results showed that at molar ratios of Ag:H2O2 = 1:1 and 1:5, dependences of changes in the intensity, position and half-width of the absorption band of the plasmon resonance are rectilinear. In vivo studies of silver nanoparticles have shown that silver nanoparticles belong to the toxicity class III (moderately hazardous substance) and to the third group according to the degree of accumulation. We established that silver nanoparticles and oxidized silver nanoparticles form a uniform layer on the surface of the suture material. We found that the use of the suture material with silver nanoparticles and oxidized silver nanoparticles does not cause allergic reactions in the organisms of laboratory animals. [ABSTRACT FROM AUTHOR]

A new type of nitrogen and chloride co‐doped carbon dots (N/Cl‐CDs) based on choline chloride–urea–glycine ternary deep eutectic solvents (DESs) was synthesized using a one‐step hydrothermal method. The prepared N/Cl‐CDs exhibited oxidase‐like activity and excellent antibacterial activity against Escherichia coli, Staphylococcus aureus and methicillin‐resistant Staphylococcus aureus (MRSA). The addition of silver nanoparticles (Ag NPs) (i.e. N/Cl‐CDs + Ag NPs) to the N/Cl‐CDs also significantly enhanced the oxidase and antibacterial activities. The nanocomposite (1·8 mg ml−1) completely inactivated 105 CFU per ml of MRSA in 90 min. E. coli and S. aureus were labelled with the N/Cl‐CDs, enabling multicolour fluorescence imaging at different excitation wavelengths. The nanocomposites have high antibacterial efficiency as a new bactericidal agent, as well as application potential with good biocompatibility and low toxicity. [ABSTRACT FROM AUTHOR]

Single particle electrochemical oxidation of polyvinylpyrrolidone-capped silver nanoparticles at a microdisk electrode is investigated as a function of particle shape (spheres, cubes, and plates) in potassium nitrate and potassium hydroxide solutions. In potassium nitrate, extreme anodic potentials (1500 mV vs Ag/AgCl (3 M KCl)) are necessary to achieve oxidation, while lower anodic potentials are required in potassium hydroxide (900 mV vs Ag/AgCl (saturated KCl)). Upon oxidation, silver oxide is formed, readily catalyzing water oxidation, producing a spike-step current response. The spike duration for each particle is used to probe effects of particle shape on the oxidation mechanism, and is substantially shorter in nitrate solution at the large overpotentials than in hydroxide solution. The integration of current spikes indicates oxidation to a mixed-valence complex. In both electrolytes, the rate of silver oxidation strongly depends on silver content of the nanoparticles, rather than the shape-dependent variable-surface area. The step height, which reflects rate of water oxidation, also tracks the silver content more so than shape. The reactivity of less-protected citrate-capped particles toward silver oxidation is also compared with that of the polymer-capped particles under these anodic conditions in the nitrate and hydroxide solutions. [ABSTRACT FROM AUTHOR]

MnO 2 –based catalysts have been widely used in the removal of short–chain volatile organic compounds (VOCs), such as propane. In this study pre–synthesized shape and size selective silver nanoparticles (AgNPs) decorated on shape dependent MnO 2 nanorods (MnO 2 NR) and nanosphere (MnO 2 NS) supports to investigate the effect of MnO 2 morphology on the complete oxidation of propane. The introduction of well–defined AgNPs on MnO 2 is greatly enabled strong metal support interactions (SMSI), reducibility, creation of oxygen vacancies and higher propane adsorption binding energy (by DFT calculation). Various analysis including HRTEM–STEM, XPS, P–XRD, FT–IR, Raman, BET, O 2 –TPD, H 2 –TPR and in–situ DRIFT–IR has been carried out in an effort to establish the mechanistic pathway, and it could be concluded that the 1Ag/MnO 2 NS has substantiated impressive catalytic activity. Further, DFT calculations supported the propane adsorption is more favorable over Ag/MnO 2 than bare MnO 2 support. The propane oxidation performance over Ag/MnO 2 NS system is remarkably higher than bare MnO 2 NR support, probably due to SMSI effect, crystal defects, increased reducibility and oxygen vacancies. Overall, it was concluded that over 1Ag/MnO 2 NS has displayed excellent catalytic activity via Mars–van–Krevelen mechanism. [Display omitted] • Synthesized different MnO 2 nanocrystal shapes & the AgNPs loaded catalysts. • Shape dependent of MnO 2 crystals are correlated with total oxidation of propane. • MnO 2 nanospheres exhibited superior activity than nanorods in propane oxidation owing to its higher O ads , enhanced O v and surface O species. • Ag NPs incorporation over MnO 2 are active than bare support due to enhanced SMSI [ABSTRACT FROM AUTHOR]

A series of porphyrin-based porous organic polymer-supported Ag nanoparticle, Ag(0)@POP -x were prepared by the reaction pathway of ion coordination followed by hydrogen reduction. The resulting composite Ag(0)@POP -6.52 shows excellent catalytic performance toward the selective oxidation of HMF to HMFCA, and an impressive HMFCA yield of 97.2% (Na 2 CO 3 2 eq, O 2 2.0 MPa 90 min, 100 °C). Analysis techniques such as ICP-OES, XRD, TEM, SEM, N 2 adsorption-desorption, and XPS was employed to characterize the structure and properties of Ag(0)@POP -6.52. The reaction conditions including the type of base and solvent, base and catalyst dosage, oxygen pressure, reaction temperature and time were studied in detail to improve the yield of HMFCA. Furthermore, the catalytic stability of the Ag(0)@POP -6.52 was evaluated by leaching and reusing tests, the results shows that the catalyst has good stability and robustness structure. Finally, the other aldehydes oxidation over Ag(0)@POP -6.52 was tested for investigation the substrate scope of Ag(0)@POP -6.52. [Display omitted] • A novel heterogeneous silver catalysts, Ag(0)@POP -6.52 was prepared. • An impressive HMFCA yield of 97.2% can be achieved over the catalysis of Ag(0)@POP -6.52 • Over-oxidation of HMF is unfavoured over Ag(0)@POP -6.52. • High reusability and structural stability are observed during synthesis of HMFCA. • Ag(0)@POP -6.52 shows high activity in the oxidation of other aromatic aldehydes. [ABSTRACT FROM AUTHOR]

The fate and toxicity of silver nanoparticles (AgNPs) and ions in water bodies is largely determined by the natural organic matter (NOM)-mediated redox cycling. However, the process of NOM-mediated redox cycling in the day/night cycles remains elusive. In this study, the inter-transformation between AgNPs and Ag+ ion caused by humic acid (HA) was investigated under controlled light and dark conditions. It was shown that HA induced the reduction of Ag+ into AgNPs in simulated sunlight, and also oxidize AgNPs to release Ag+ in darkness. Kinetics data demonstrated that the rates of AgNPs formation and dissolution increased along with the increment of HA concentrations. Along with the pH increase, the reduction of Ag+ accelerated, but the oxidative dissolution of AgNPs was inhibited. In day-night cycles, the AgNPs and Ag+ concentrations exhibited similar wave-shaped change curves. The peaks of AgNPs and Ag+ ion appeared at 7 p.m. and 7 a.m., respectively. The toxicity of AgNPs/Ag+ to Escherichia coli was determined primarily by the concentration of dissolved Ag+, but also affected by the particle-specific toxicity. The dual role of HA implied that previous reports about the photo-reduction of Ag+ to AgNPs by NOM should be reconsidered, and the oxidizability of HA in darkness strongly affect the transformation and toxicity of AgNPs in water. [ABSTRACT FROM AUTHOR]

In this work, we obtained silver nanoparticles stabilized with polyvinylpyrrolidone, ranging in size from 70 to 110 nm, which exhibits good crystallinity and anisotropic structure. For the first time, we studied the influence of the molar ratio of silver between silver and peroxide on the oxidation process of the nanoparticles and determined the regularities of this process by analyzing changes in absorption spectra. Our results showed that at molar ratios of Ag:H2O2 = 1:1 and 1:5, dependences of changes in the intensity, position and half-width of the absorption band of the plasmon resonance are rectilinear. In vivo studies of silver nanoparticles have shown that silver nanoparticles belong to the toxicity class III (moderately hazardous substance) and to the third group according to the degree of accumulation. We established that silver nanoparticles and oxidized silver nanoparticles form a uniform layer on the surface of the suture material. We found that the use of the suture material with silver nanoparticles and oxidized silver nanoparticles does not cause allergic reactions in the organisms of laboratory animals.

Antibacterial gauze is commonly used to prevent wound inflammation and infection. In this study, a novel antibacterial gauze was prepared using antimicrobial peptides and silver nanoparticles, achieving a wide antimicrobial spectrum and increased antimicrobial properties. The properties of the antibacterial gauze were analyzed by scanning electron microscopy, energy-dispersive spectrometry, weight gain rate test, Fourier transform infrared spectroscopy, antibacterial test, and cell activity test. The results of energy-dispersive spectrometry and Fourier transform infrared spectroscopy suggested that the antimicrobial peptides and silver nanoparticles were loaded on the surface of the gauze. The prepared gauze exhibited excellent antibacterial properties against Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, and Bacillus cereus due to the synergistic antibacterial effect of the antimicrobial peptides and silver nanoparticles. Compared with antibacterial gauze loaded with high concentrations of silver nanoparticles, the gauze prepared here has better antimicrobial properties and no obvious cytotoxicity to cells. These results indicate that this antibacterial gauze, with good compatibility, is an attractive candidate for application in wound care and wound healing. [ABSTRACT FROM AUTHOR]

The results of X-ray photoelectron spectra (XPS) characterization of the surface of Ag-Au colloidal nanoparticles (Ag-Au NPs), prepared by laser ablation in water before and after interaction with linear carbon chains (LCC), are presented. No additional features appear in high-energy resolved XPS core level spectra of Ag-Au NPs which indicates that surface is not oxidized. The measurements of XPS Ag 3d-spectrum of (Ag-Au)@LCC manifests the additional low-energy structure that is associated with the formation of Ag–C bonds. The charge transfer between Au atoms on the NPs surface and LCC was established. Additionally, some oxidation of the Ag atoms on the surface of (Ag-Au)@LCC is observed which arises during laser ablation in water. We assume that oxidative species will preferably interact with the areas outside the LCC instead of oxidizing the carbon chains which was confirmed by XPS C 1s spectra. [ABSTRACT FROM AUTHOR]

The selective catalytic oxidation of cyclohexane has important theoretical and practical application value. However, high conversion rate and high selectivity are difficult to achieve simultaneously by conventional catalytic system. In this work, blue molybdenum trioxide (MoO 3) nanorods with oxygen vacancies were prepared by hydrothermal method using hydrated molybdic acid as a precursor under the reduction of formic acid, and in-situ produced MoO 3 -silver (MoO 3 -Ag) composites were further used in the photothermal catalytic oxidation of cyclohexane with high conversion and high selectivity using dry air as oxidant. The results showed that the best conversion rate of cyclohexanone and cyclohexanol (KA oil) could reach 8.6% with the selectivity of 99.0%. The excellent catalytic performance of MoO 3 -Ag composites can be attributed to the significantly increased visible and near-infrared light absorption caused by the plasma resonance effect of Ag nanoparticles and oxygen vacancies, and the prevented charge recombination by MoO 3 -Ag Schottky heterojunction. This work provides new reference solutions for the design and preparation of high-performance photothermal catalysts for the selective oxidation of hydrocarbons. [ABSTRACT FROM AUTHOR]

The two-step decoration of the Ag nanoparticles supported on carbon black (Ag/C) with Au and Pt, the electrooxidation of glycerol on the Pt/Au/Ag/C catalysts in alkaline solution, and the effect of the amounts of Au and Pt on the catalytic activity of Pt/Au/Ag/C are investigated. The decoration of Ag/C is performed by electrochemically depositing a small amount of Au and then Pt on Ag/C, and the Pt x /Au y /Ag 100 /C catalysts with different x : y :100 ratios (0.15 ≤ x ≤ 1.9 and 0.2 ≤ y ≤ 1.5) are obtained. Physical and electrochemical characterizations reveal that small parts of the Ag surfaces are covered by the deposited Au and Pt. Pt x /Au y /Ag 100 /C mainly shows Pt-relevant behaviors in glycerol oxidation, and Pt 1.3 /Au y /Ag 100 /C exhibits high catalytic activities. The results reveal that the surface decoration is a useful method of fabricating efficient ternary catalysts at low cost. • Pt/Au/Ag/C is prepared by decorating Ag/C with small amounts of Au and Pt. • Activity of Pt/Au/Ag/C depends on the decoration sequence and masses of Au and Pt. • Pt 1.3 /Au y /Ag 100 /C (y ≤ 1.5) shows high catalytic activity for glycerol oxidation. [ABSTRACT FROM AUTHOR]

Steady developments made in nanotechnology-based products have facilitated new perspectives for combating drug-resistant fungi. Silver nanoparticles represent one of the most attractive nanomaterials in biomedicine due to their exclusive optical, electromagnetic, and catalytic properties and antifungal potency compared with other metal nanoparticles. Most studies show that the physicochemical parameters affecting the antifungal potential of AgNPs include the shape, size, surface charge, and concentration and colloidal state. For the present study, pullulan (P) and its oxidized counterpart (PO) have been selected as matrices for the silver nanoparticles’ generation and stabilization (AgNPs). The TEMPO (2,2,6,6-tetramethylpiperidin-1-yl radical)–sodium hypochlorite–sodium bromide system was used for the C6 selective oxidation of pullulan in order to introduce negatively charged carboxylic groups in its structure. The structure and morphology of the synthesized AgNPs were analyzed using FTIR and EDX. The main objective of this study was to elucidate the antifungal activity of AgNPs on the clinical yeasts isolates and compare the performance of AgNPs with the conventional antifungals. In this study, different concentrations of AgNPs were tested to examine antifungal activity on various clinical isolates.

The influence of different types of plasmonic gold (Au-NPs) and silver (Ag-NPs) nanoparticles as well as aging on the performance of Surface-Enhanced Raman Scattering (SERS) sensors were studied. The average diameters of Au-NPs and Ag- NPs were about 23 nm and 15 nm, respectively, with a number of laser pulses of about 200. plasmonic nanoparticles were synthesized by laser ablation process in distilled water using a fixed energy laser fluence of about 14 J/cm2 of Nd-YAG laser, with 1060 nm wavelength and 1 Hz pulse repetition rate. The SERS sensor was carried out by quick drop casting process of plasmonicplasmonic nanoparticles on glass substrates. The morphological aspects and the performance of SERS sensors were investigated by high resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. All the results indicated the significant dependence of the performance of the sensor on the types of the plasmonic nanoparticles . The obtained Raman signal intensity of Ag-NPs was about 105a.u. compared with 105a.u. for Au-NPs. While, the stability of Au-NPs was much higher than that of Ag-NPs based on SERS sensors due to the normal oxidation process of Ag-NPs. [ABSTRACT FROM AUTHOR]

Manufacturing a flexible, light, large-area, and high-efficiency electromagnetic shielding materials in a straightforward and cost-effective manner presently remains a significant challenge. In this work, we propose a conductive network design and verify its electromagnetic interference (EMI) shielding effectiveness (SE) by simulation. Using the structure and parameters obtained by simulation, we prepare a flexible EMI shielding material using silver nanowires (AgNWs)/polyvinyl butyral (PVB) ethanol solution and textile substructure via a facile immersing method. In the frequency range of 5–18 GHz, the AgNWs/PVB textile with 1.4 mm thickness achieves an EMI SE of 59 dB, which exceeds the requirements for commercial applications. Due to the low density of 56 mg/cm3, specific shielding effectiveness (SSE) of this material reaches 1053 dB m3/g. It is found that the AgNWs/PVB textile is more resistant to washing with water and oxidation than AgNWs textile without a PVB protector. As a result, the conductivity of AgNWs/PVB textile exhibits no change after washing with water and varies slightly after being kept in hot air. We find that a signal monitor is unable to detect a signal emitted by a mobile phone from a jacket lined with AgNWs/PVB textile. AgNWs/PVB textile with these properties can be mass-produced as high-efficiency EMI shielding material for commercial applications. [ABSTRACT FROM AUTHOR]

Aromatic amines such as 4-nitroaniline (4-NA) are commonly released into the environment by wastewaters containing azo colors. In the present study, silver nanoparticles were synthesized using the extract of Damask rose. Then, its physicochemical properties were determined. The effects of parameters such as pH, contact time, persulfate (PS) concentration, and nanosilver (NS) concentration on 4-NA removal were studied by a cylindrical reactor placed in ultrasound (US) device. The results showed that the efficiency of 4-NA removal by the US/PS/NS process increased with increasing the dose of NS and PS, as well as the contact time. pH had no significant effect on the removal efficiency even though in acidic pHs the removal efficiency was 5% higher. Also, over time, the pH of the reactor decreased due to the reactions occurring; this caused the same efficiency at different pHs. In the US/PS/NS process, increasing the initial 4-NA concentration also reduced the efficiency slightly. Under the optimal conditions, including pH = 5, contact time = 90 min, US power = 60 W, NS concentration = 300 mg/L, and PS concentration = 1.68 mM, the US/PS/NS process could reduce 4-NA up to 93%. [ABSTRACT FROM AUTHOR]

One of the possible ways for using silver nanoparticles (AgNPs) in spectrophotometry is their application for the determination of oxidizing agents, based on oxidative destruction of these nanoobjects. This process depends on the structure of AgNPs surface layer, which is essentially affected by the chosen stabilizer. To assess influence of the nanoparticle stabilizer and the nature of the analyte, possibilities of AgNPs covered with stabilizers of three types (citrate, polyvinylpyrrolidone, and polyhexamethylene guanidinium) for the spectrophotometric determination of hydrogen peroxide and differently substituted organic peroxides were studied. The approach is based on AgNPs oxidation leading to discoloration of the solution monitored spectrophotometrically. Different selectivity of the oxidation depending on the stabilizer was shown. Effects of various factors (time of interaction, pH, concentration of AgNPs) on the oxidation and analytical performance of the procedure were investigated. The method allows for the determination of hydrogen peroxide, peracetic acid, m -chloroperbenzoic acid, and t -butylhydroperoxide in the range of 0.3–1.5, 0.1–0.8, 1.0–7.5, and 1–7 μg mL−1 and with the limits of detection of 0.1, 0.04, 0.3, and 0.3 μg mL−1, respectively. The analysis can be performed using either spectrophotometry or naked-eye detection. Image 1 • Oxidation of AgNPs covered with stabilizers of three types by peroxides were studied. • The type of an AgNPs stabilizer plays an important role in their oxidation. • Hydrogen peroxide and differently substituted organic peroxides are considered. • Best strategies for the determination of peroxides using AgNPs are proposed. [ABSTRACT FROM AUTHOR]

Highlights • Preparation of nano-Ag/TiO 2 catalyst from silver nitrate and Tulsi leaf extract. • Characterisation and application of Ag/TiO 2 catalyst in thiophene oxidation. • Both pseudo-homogeneous and heterogeneous rate models are proposed. • Endothermicity of the reaction was established by thermodynamic analysis. • Surface reaction is found to be the rate limiting step following L-H kinetic model. Abstract The present research work describes the preparation of silver nanoparticles from silver nitrate, and Tulsi (Ocimum tenuiflorum) leaf extract, impregnation on titanium dioxide (TiO 2) and evaluation of the catalytic activity of this nano silver impregnated TiO 2 in the oxidation reaction of thiophene. Tertiary-butyl hydroperoxide was used as an oxidant in the reaction. The catalyst was characterized by BET, SEM, XRF, TEM, UV–Vis spectroscopy, XPS and TPR. The effect of process parameters such as speed of agitation, catalyst weight, oxidant to sulfur mole ratio, silver loading in the catalyst and temperature on the oxidation reaction was studied. Both pseudo-homogeneous and heterogeneous kinetic models were considered and applied for the result. The pseudo-homogeneous form of rate equation shows the reaction follows second order kinetics and is endothermic. Langmuir-Hinshelwood kinetic model is proposed, considering the reaction as a heterogeneous one with solid catalyst and found that surface reaction is the rate controlling step. This model is well fitted with experimental data. [ABSTRACT FROM AUTHOR]

Abstract Ratiometric sensing suffers from less interference and can obtain more accurate results than single-signal assay. Here, a new ratiometric optical sensing strategy for H 2 O 2 detection is developed by etching silver nanoparticles (AgNPs) to deactivate fluorescence resonance energy transfer (FRET) and reduce Rayleigh scattering based on a hyphenated technique of fluorescence and second-order Rayleigh scattering (SRS). The ratiometric detection of H 2 O 2 is achieved through exploiting a hybrid system fabricated by fluorescent carbon dots and silver nanoparticles (CDs/AgNPs). In the CDs/AgNPs system, the fluorescence of CDs is quenched because of FRET, and the scattering is strong due to the intrinsic high light-scattering power of AgNPs. With the introduction of H 2 O 2 , the AgNPs are etched and the CDs are released from the AgNP surface, resulting in the fluorescence enhancement and scattering decline. As a result, ratiometric sensing of H 2 O 2 can be achieved based on the CDs/AgNPs system by simultaneous collection of fluorescence and SRS signals. The sensing system is further used for H 2 O 2 -generation bioanalysis, and as a proof-of-concept, ratiometric assay of glucose and evaluation of glucose oxidase activity are performed successfully. This work provides a new perspective for sensing applications of plasmonic nanoparticles. Graphical abstract Image 1 Highlights • A ratiometric sensor of H 2 O 2 was fabricated by Ag nanoparticles (AgNPs) and carbon dots (CDs). • The sensor was developed by combining fluorescence and second-order Rayleigh scattering. • The CDs/AgNPs system was endowed with weak fluorescence and strong scattering. • Fluorescence increased and scattering declined after AgNPs were etched by H 2 O 2. • The sensor was extended to ratiometric assay of glucose and glucose oxidase activity. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, silver nanoparticles (AgNPs) are the most widely used nanoparticles (NPs) in the industry due to their peculiar biocidal features. However, the use of these NPs still runs into limitations mainly because of the low efficiency of environmental friendly synthesis methods and lack of size standardization. When NPs are release in the environment, they can be transformed by oxidation, adsorption or aggregation. These modification shows a dual role in toxic response of AgNPs. The adsorption of natural organic matter from environment on AgNPs, for example, can decrease their toxicity. Otherwise oxidation occurred in the environment is also able to increase the release of toxic Ag+ from NPs. Thus, the current review proposes an integrated approach of AgNP synthetic methods using bacteria, fungi, and plants, AgNP cytotoxic and genotoxic effects as well as their potential therapeutic applications are also presented. Graphical abstract fx1 Highlights • The AgNPs cytotoxicity can be used for therapeutic applications. • AgNPs released into the environment may react with various compounds found in aquatic organic matter • There are environmental friendly AgNP synthetic methods using bacteria, fungi, and plants. • The improvement of green synthesis methods will allow a better modeling of the AgNPs physicochemical characteristics. • The development of efficient green synthetic methods will contribute to potentiate AgNPs therapeutic effect. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Graphene oxide (GO) has gained popularity in scientific research and industry due to its superior properties, which can be controlled by the synthesis method and graphite feedstock. Despite the availability of different graphite sources, most of the reported studies used natural graphite flake (NGF) as a source of oxidation for GO synthesis. The effect of various alternative graphite feedstocks on the GO properties has not been investigated systematically. This study investigated the influence of graphite feedstock (natural and synthetic) on the characteristics and properties of GO via modified Hummer's method. Natural graphite flake (NGF), natural graphite powder (NGP), and synthetic graphite powder (SGP) were used as graphite feedstock in the study. Energy-dispersive X-ray analysis revealed that the GO produced using NGP (NGP-GO) has higher oxygen to carbon ratio in comparison to GO made from NGF (NGF-GO) and GO made from SGP (SGP-GO) (35.4, 32.7, and 32.2%, respectively), indicating higher oxidation degree for NGP-GO. Zeta potential analysis for NGP-GO, NGF-GO and SGP-GO were −47.8, −42.6 and −39.4 mV, respectively. Morphological analysis revealed that the structures of GO varied according to graphite feedstock, in which (NGP-GO) and (NGF-GO) were highly exfoliated (single-layered structure) while (SGP-GO) showed a multi-layered structure. Further testing was conducted by decorating silver (Ag) nanoparticles on the GO. The results showed that Ag could be uniformly decorated (no agglomeration) on the surface of GO-NGP, due to the presence of more functional groups. Subsequently, the antimicrobial property of Ag-NGP was the highest with an inhibition diameter of 14.7 ± 1.2 mm (30% higher than the other samples). In conclusion, the properties of GO can be tuned by selecting the suitable graphite feedstock and this might pave the way to new developments in the GO-based applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ag/BN nanohybrids produced via AgNO 3 decomposition under UV irradiation in polyethylene glycol. • Ag/BN nanohybrids and Ag polymer-based metallogels formed simultaneously during the synthesis. • Catalysts obtained in PEG showed higher concentration and uniform distribution of Ag nanoparticles. • Ag/BN nanohybrids demonstrated a pronounced catalytic activity toward CO oxidation. Abstract Nanohybrid materials made of h -BN nanoparticles (BNNPs) with Ag nanoparticles (AgNPs), covering their surfaces, were employed as catalysts in CO oxidation reaction. Ag/BN nanohybrids (NHs) were produced via AgNO 3 decomposition under UV irradiation in polyethylene glycol (PEG) and its solutions at room temperature. Influence of the synthetic media composition on the synthesis process and resultant NHs structures were investigated. Two different structural types (Ag/BN and polymer-based structure) formed during the synthesis were studied. It was demonstrated that Ag/BN NHs synthesized in a PEG media had possessed the highest Ag concentration and uniform distribution of AgNPs. Catalytic activity tests revealed that the lowest temperature of full CO conversion (194 °C) had been attained to the sample with the highest Ag content. CO oxidation mechanism on the surface of AgNPs was finally proposed based on DFT calculations. [ABSTRACT FROM AUTHOR]

Extracted microcrystalline cellulose from Carthamus tinctorius plant was oxidized by sodium metaperiodate and a novel molybdenum schiff base complex was supported on this natural cellulose (MoSMC@MC). Then, micro biopolymer silver/ immobilized molybenum complex on natural cellulose (Ag/MoSMC@MC) was synthesized at the presence of Sesbania sesba plant and charaterized by SEM, FT-IR, TGA, and EDAX. The catalytic efficiency of Ag/MoSMC@MC was exploited as a heterogenous bio-catalyst in the selective oxidation of alcohols. The reactions were conducted using catalytic amounts of Ag/MoSMC@MC and t-BuOOH under solvent free conidtion to obtain desired aldehydes and ketones in high yields and excellent selectivity. Long-term stability and reproducibility in consecutive runs were feature of this microcomposite. At second part of this work, a novel strategy was reported to obtain green nanocomposites. Herein, addition of silver nitrate to plant solution led to the decomposition of the organic to inorganic polymer. As results, MoO 3 /Ag nanocomposite was prepared and its characteristics were investigated using TEM, and XRD to confirm the shape and structure. [ABSTRACT FROM AUTHOR]

Abstract: A silver‐promoted oxidative benzylic C−H trifluoromethoxylation has been reported for the first time. With trifluoromethyl arylsulfonate as the trifluoromethoxylation reagent, various arenes, having diverse functional groups, undergo trifluoromethoxylation of their benzylic C−H bonds to form trifluoromethyl ethers under mild reaction conditions. In addition, the trifluoromethoxylation and the fluorination of methyl groups of electron‐rich arenes have been achieved to prepare α‐fluorobenzyl trifluoromethyl ethers in one step. [ABSTRACT FROM AUTHOR]

[Display omitted] • Prepared a morphology and shape controlled AgNPs/α–MnO 2 NRs catalysts. • Ag NPs with MnO 2 nanorods interface created higher oxygen vacancies. • AgNPs/α–MnO 2 NRs had strong metal support interactions. • Introduction of Ag NPs over MnO 2 enhanced the BnOH adsorption rate. • Over 1 wt% AgNPs/ α–MnO 2 NRs shown higher activity than bare MnO 2. Vapor phase benzyl alcohol (BnOH) oxidation reaction is investigated over a pre–synthesised morphologically designed shape controlled spherical silver nanoparticles (AgNPs) decorated on manganese oxide nanorods (α–MnO 2 NRs) in the presence of air. The combination of silver nanoparticles and the α–MnO 2 NRs interface enabled the increased oxygen vacancies (O v) and exhibited the strong metal–support interactions (SMSI) in surface oxygen activation. The effect of Ag loadings is significant and the optimal 1 wt% Ag loaded catalyst (1Ag/MnO 2 NRs) showed excellent performance in benzyl alcohol oxidation due to high adsorption capacity, enhanced oxygen vacancies and red–ox properties. The DFT calculations confirmed that the high BnOH surface adsorption was exhibited over Ag modified MnO 2 NRs than the bare α–MnO 2 NRs. The optimized 1Ag/α–MnO 2 NRs catalytic system achieved 2.6 fold higher activity compared to bare α–MnO 2 NRs. These results provided novel insights on the rational design of shape dependent metal/metal oxide based heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Carey Lea silver hydrosol is a rare example of very concentrated colloidal solutions produced with citrate as only protective ligands, and prospective for a wide range of applications, whose properties have been insufficiently studied up to now. Herein, the reactivity of the immobilized silver nanoparticles toward oxidation, sulfidation, and sintering upon their interaction with hydrogen peroxide, sulfide ions, and chlorocomplexes of Au(III), Pd(II), and Pt(IV) was investigated using SEM and X-ray photoelectron spectroscopy (XPS). The reactions decreased the number of carboxylic groups of the citrate-derived capping and promoted coalescence of 7 nm Ag NPs into about 40 nm ones, excluding the interaction with hydrogen peroxide. The increased nanoparticles form loose submicrometer aggregates in the case of sulfide treatment, raspberry-like micrometer porous particles in the media containing Pd(II) chloride, and densely sintered particles in the reaction with inert H2PtCl6 complexes, probably via the formation of surface Ag-Pt alloys. The exposure of Ag NPs to HAuCl4 solution produced compact Ag films along with nanocrystals of Au metal and minor Ag and AgCl. The results are promising for chemical ambient temperature sintering and rendering silver-based nanomaterials, for example, for flexible electronics, catalysis, and other applications.

The physical and chemical properties of materials are greatly influenced by the state of their surface layers. In turn, the characteristics of the surface depend, for example, on the processes of absorption from a gas medium. In this study, by in situ measurements, the surface layers of polycrystalline silver exposed to external activated oxygen from different sources are investigated. For sources of activated oxygen, water vapor at a temperature of 1073 K and an ion source that makes it possible to obtain an oxygen ion beam with the energy 100–300 eV (5 μA/cm2) are used. It is established that, after treatment, the composition of AgO and Ag2O in the surface layers of silver includes, apart from atomic oxygen, molecular oxygen and silver in the zero-valence state. From estimates of the ratio between the intensities of spectroscopy peaks related to silver and oxygen components, it can be concluded that there exist associative forms of oxygen in the surface layers of silver. An increase in Ag 3d5/2–Ag 3d3/2 spin–orbit splitting is detected, which suggests that there are oxidized silver nanoparticles on the surface. [ABSTRACT FROM AUTHOR]

Zeolites with Rho, Beta, and paulingite structures, modified with silver nanoparticles and clusters, are prepared, and their catalytic performances in hydrogen and carbon monoxide oxidation reactions are investiagted. The prepared zeolite samples have different silver loads (up to 25 wt %), and the loaded silver exists in the form of nanoparticles and clusters having a different nuclearity (Ag8+,Ag42+,Ag4+). Silver clusters were detected and identified using UV−Vis spectroscopy. It is established that the catalytic performance of our silver-modified zeolites varies with the silver load, the form the loaded silver assumes (nanoparticles and/or clusters of a different nuclearity, and their ratio), and the structural type of zeolite matrix. [ABSTRACT FROM AUTHOR]

In an effort to verify a previous striking report that ethanol could be oxidized selectively to ethylene oxide, ethanol oxidation on Ag, Cu, or Au nanoparticles supported on Li 2 O/γ-Al 2 O 3 or γ-Al 2 O 3 was examined between 100 and 400 °C. Ag and Cu catalysts were found to be highly selective to acetaldehyde (>95% on Ag below 325 °C and on Cu below 250 °C). On Au, selectivities to acetaldehyde were lower, with higher selectivity to ethyl acetate and acetic acid. No ethylene oxide was observed under any conditions. Our results, including selectivity variations among these metals, are consistent with previous studies of ethanol oxidation over coinage metals supported on γ-Al 2 O 3 , with no changes in primary product identity and minor changes in selectivity upon addition of Li 2 O. Unfortunately, these results are in direct contradiction to previous work reporting the desirable direct conversion of ethanol to ethylene oxide on Ag, Cu, and Au on Li 2 O/γ-Al 2 O 3 . [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) were prepared by a green method using Cordia myxa leaf extract. They were characterised by UV–vis spectroscopy, Fourier transform infrared spectroscopy and their X‐ray diffraction pattern. Their sizes were determined by scanning electron micrographs, transmission electron micrographs imaging and dynamic light scattering analysis. The shapes of nanoparticles were spherical or truncated triangular and their average size was determined to be 51.6 nm. Their solution was stable at least for one month. The prepared AgNPs were used as a selective chemical sensor for determination of iron(III) (only when Cl− ions were present in the medium) and mercury(II) ions with detection limits of 0.084 and 0.037 nM, respectively. It was shown that the mechanism of these detections is through oxidation of Ag atoms by Fe3+ and Hg2+ ions. [ABSTRACT FROM AUTHOR]

Present work covers the state-of-art progress in the advanced nanoarchitecture of organic-inorganic hybrid material; a starting material for the antimicrobial filter. TEMPO-mediated oxidation of microfiber cellulose was carried out to introduce the surface active carboxyl groups. Accordingly, qualitative and quantitative substitution of a functional group was investigated using FTIR, Solid state 13 C CP/MAS NMR , and potentiometric titration; the reaction resulted to about 21.06% increase in carboxylate content. Further, the microwave irradiated (600 W) in-situ synthesis of AgBr and AgCl nanocubes were prepared and doped on carboxylated microfiber. The prepared AgBr@TO-MF and AgCl@TO-MF were tested using XRD, XPS, SEM and FTIR. With an average size of AgBr and AgCl nanocubes of around 200 ± 28 nm and 116 ± 10.73 nm. Whereas, AgBr@TO-MF and AgCl@TO-MF shown excellent antimicrobial activity against E. Coli and B. Subtilis , with MIC at around 200 μg/mL and 150 μg/mL, respectively. Fascinatingly, ICP-OES analysis estimated the silver leached was around 0.1 ppm. [ABSTRACT FROM AUTHOR]

The physicochemical properties of silver nanoparticles (AgNPs) in human whole saliva are investigated herein. In authentic saliva samples, AgNPs exhibit a great stability with over 70% of the nanomaterial remaining intact after a 24-h incubation in the presence of ∼0.3 mM dissolved oxygen. The small loss of AgNPs from the saliva sample has been demonstrated to be a result of two processes: agglomeration/aggregation (not involving oxygen) and oxidative dissolution of AgNPs (assisted by oxygen). In authentic saliva, AgNPs are also shown to be more inert both chemically (silver oxidative dissolution) and electrochemically (electron transfer at an electrode) than in synthetic saliva or aqueous electrolytes. The results thus predict based on the chemical persistence (over a 24-h study) of AgNPs in saliva and hence the minimal release of hazardous Ag+ and reactive oxygen species that the AgNPs are less likely to cause serious harm to the oral cavity but this persistence may enable their transport to other environments. [ABSTRACT FROM AUTHOR]

The biological method for synthesis of silver nanoparticles (AgNPs) using Bacopa monneri leaves and its anti‐proliferation against human lung adenocarcinoma cell line (A549) was studied. The AgNPs synthesis was determined by an ultraviolet–visible spectrum and was confirmed primarily by the colour change and surface plasmon resonance was observed at 450 nm and its reduction of functional groups stretched in AgNPs was identified by Fourier transform infrared and the crystalline nature of AgNPs was confirmed by X‐ray diffraction. The structural morphology of the AgNPs was found to be spherical and polygonal shape and size (> 35 nm) were determined by field emission scanning electron microscopy analysis and its purity was identified by energy dispersive analysis of X‐rays (EDAX). A further, antibacterial activity of biosynthesised AgNPs against Gram negative and Gram positive bacteria was assessed. The cytotoxic effect of synthesised AgNPs was analysed against human lung adenocarcinoma cells by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. The GI50 was found to be 20 µg/ml at 24 h incubation. The apoptosis cells containing condensate and marginalised chromatin stages were analysed by propidium iodide staining and DNA damage was observed in A549 treated cells. The present study strongly emphasised that the bioactive molecule‐coated AgNPs could have potential for biomedical applications and significant anticancer effects against human lung adenocarcinoma cells. [ABSTRACT FROM AUTHOR]

A portable electrophoresis device based on the SU-8/Pyrex microfluidic chip with integrated three 100 µm platinum (Pt) thin-film electrodes (working, reference, and auxiliary) was adapted for the analysis of silver nanoparticles (AgNPs). The microfluidic platform includes the main electrophoresis instrument, reusable holder, and microfluidic chip with integrated Pt electrodes. The electrochemical oxidation behaviours of AgNPs on Pt thin-film electrode were investigated by using cyclic voltammetry, while the electrophoresis behaviours of AgNPs were studied on the 'Lab-on-a-chip' platform. The influences of parameters including running buffer, separation voltage, and detection potential on the electrophoresis behaviours of AgNPs were all investigated. The results showed that AgNPs could be oxidised at 0.2-0.4 V [phosphate buffer solution buffer, pH 7.0] on the Pt thin-film electrode. The peak current enhanced with the increase of separation voltage, while the retention time decreased. The peak current varied with the detection potential and reached the highest value at 0.4 V. This microfluidic platform could be a fast and portable detection system for the analysis of total AgNPs. [ABSTRACT FROM AUTHOR]

By immobilizing Ag nanoparticles to UiO-66, a series of nanocatalysts (Ag/UiO-66) were synthesized and used as catalysts for oxidation of styrene. The catalytic efficiency could be optimized by altering Ag loadings of Ag/UiO-66, solvents, the molar ratios of styrene to tert-butyl hydroperoxide (TBHP) and reaction temperatures. Interestingly, the Ag loadings 1.86 wt% of Ag/UiO-66 exhibited high conversion, selectivity and recyclability in the selective oxidation of styrene. [ABSTRACT FROM AUTHOR]

One-step synthesis of wet chemical method is proposed for the preparation of core-shell nanostructures of copper and silver. This facile and environment friendly fabrication simplifies the surface treatment of copper particles to avoid copper core to be oxidised before coating silver. The thermal stability against oxidation and electrical properties of Cu@Ag core-shell nanoparticles are investigated. The results show that Cu@Ag core-shell nanoparticles possess high spherical degree, and the silver is evenly coated on the surface of copper nanoparticles. The synthesised spherical Cu@Ag core-shell nanoparticles exhibit excellent thermal stability at the high temperature of 300°C. After annealing at 200°C for 30 min, the sheet resistance of the spherical Cu@Ag core-shell nanoparticles (Ag content 7.68 wt%) is extremely low (69.82 μΩ cm). [ABSTRACT FROM AUTHOR]

The mixed silver-copper oxide Ag 2 Cu 2 O 3 with a paramelaconite crystal structure is a promising material for catalytic applications. The as-prepared sample of Ag 2 Cu 2 O 3 consisted of brick-like particles extended along the [001] direction. A combination of physicochemical techniques such as TEM, XPS and XRD was applied to investigate the structural features of this mixed silver-copper oxide. The thermal stability of Ag 2 Cu 2 O 3 was investigated using in situ XRD under different reaction conditions, including a catalytic CO + O 2 mixture. The first step of Ag 2 Cu 2 O 3 decomposition was accompanied by the appearance of ensembles consisting of silver nanoparticles with sizes of 5–15 nm. Silver nanoparticles were strongly oriented to each other and to the surface of the initial Ag 2 Cu 2 O 3 bricks. Based on the XRD data, it was shown that the release of silver occurred along the a and b axes of the paramelaconite structure. Partial decomposition of Ag 2 Cu 2 O 3 accompanied by the formation of silver nanoparticles was observed during prolonged air storage under ambient conditions. The high reactivity is discussed as a reason for spontaneous decomposition during Ag 2 Cu 2 O 3 storage. The full decomposition of the mixed oxide into metallic silver and copper (II) oxide took place at temperatures higher than 300 °C regardless of the nature of the reaction medium (helium, air, CO + O 2 ). Catalytic properties of partially and fully decomposed samples of mixed silver-copper oxide were measured in low-temperature CO oxidation and C 2 H 4 epoxidation reactions. [ABSTRACT FROM AUTHOR]

P(AA)-Ag heterogeneous catalyst system comprised of Ag nanoparticles embedded within hydrogel matrices has been described for the selective aerobic oxidation of alcohols and reduction of nitro phenols in water. P(AA)-Ag nanocomposite was characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), X-Ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectrometer (ICP). Catalytic activity of p(AA)-Ag catalyst was investigated in the aerobic oxidation of primary alcohols and reduction of nitro compounds by emphasizing the effect of different parameters such as temperature, catalyst amount, substituent effect, etc. The catalyst was easily recovered from the reaction medium and it could be re-used for other three runs without significant loss of activity. [ABSTRACT FROM AUTHOR]

A novel, selective and sensitive colorimetric detection method for Hg2+is developed using Bismarck brown R (BBR) reductive products-immobilised silver nanoparticles (BBR products-AgNPs) as a sensing probe. In this research, the BBR reductive products were synthesisedin situand immediately immobilised on the surface of AgNPs. A surface plasmon resonance band of BBR products-AgNPs was observed at 396 nm. The absorbance at 396 nm gradually decreased, and a remarkable blue shift from 396 to 368 nm and a colour change from yellow to colourless by increasing the Hg2+concentration were observed. This observation is due to the oxidation of Ag° to Ag+and the reduction of Hg2+to Hg° during the process, and thus Ag–Hg nanoalloy is formed. In addition, an exploratory study of the designed system is done by chemometrics approaches with the aim of making a clear perspective from the reaction system. The effective parameters for detection of Hg2+based on the BBR products-AgNPs as optical probe were optimised. Under optimal conditions, the sensor exhibited a high selectivity and sensitivity with limit of detection of 6.1 nM (1.66 µg L−1) and the linear range from 0.01–19.0 µM (2.72–5160 µg L−1). The proposed method was simple, rapid and cost-effective without any complicated operation. Finally, it was successfully used for detection of Hg2+in water samples with recoveries ranges of 86.7–103.6% and relative standard deviation slower than 10.1%. [ABSTRACT FROM PUBLISHER]

The oxidative dissolution of citrate-capped silver nanoparticles (AgNPs, ∼50 nm diameter) is investigated herein by two electrochemical techniques: nano-impacts and anodic stripping voltammetry. Nano-impacts or single nanoparticle-electrode collisions allow the detection of individual nanoparticles. The technique offers an advantage over surface-immobilized methods such as anodic stripping voltammetry as it eliminates the effects of particle agglomeration/aggregation. The electrochemical studies are performed in different electrolytes (KNO3, KCl, KBr and KI) at varied concentrations (≤20 m m). In nano-impact measurements, the AgNP undergoes complete oxidation upon impact at a suitably potentiostated electrode. The frequency of the nanoparticle-electrode collisions observed as current-transient spikes depends on the electrolyte identity, its concentration and the potential applied at the working electrode. The frequencies of the spikes are significantly higher in the presence of halide ions and increase with increasing potentials. From the frequency, the rate of AgNP oxidation as compared with the timescale the AgNP is in electrical contact with the electrode can be inferred, and hence is indicative of the relative kinetics of the oxidation process. Primarily based on these results, we propose the initial formation of the silver (I) nucleus (Ag+, AgCl, AgBr or AgI) as the rate-determining process of silver oxidation on the nanoparticle. [ABSTRACT FROM AUTHOR]