Ag Source Research Articles

Monitoring of clinical drug osimertinib based on red phosphorus@silver composite SERS substrate synthesized by a photo-induced in-situ reduction method

Surface enhanced Raman scattering (SERS) with high detection sensitivity has emerged as a fascinating protocol for monitoring trace amount of drugs in clinical serum sample. Herein, a simple and environmentally friendly photo-induced in-situ reduction strategy was proposed to synthesize RP@Ag composites with both SERS and photocatalytic activities. By carefully adjusting the concentration of the Ag source in the precursor solution, the amount and diameter of the decorated Ag nanoparticles were precisely tuned. The resulting optimal RP@Ag composites exhibited reliable SERS enhancement ability (enhancement factor: 1.76 × 107) and the highest degradation efficiency (degradation ratio: 95.04 %, irradiation time: 120 mins) in recyclable detection of Rhodamine B. After further confirming the reliable accuracy, sensitivity, homogeneity, and durability of the RP@Ag composites, they were used to monitor osimertinib and enabled an extremely low limit of detection as 1.63 × 10−7 mg/mL. In particular, such a recyclable SERS platform achieved perfect recovery rates, the obtained deviations were all within 10 % in the monitoring of clinical samples from patients taking medicine for different durations.

Mixing behaviour and sources of Ag, Pd, and other trace elements in the Estuary and Gulf of St. Lawrence under winter conditions

The marine chemistry of platinum group elements is poorly documented despite robust evidence of their widespread emissions and deposition around the globe. Here, we report the concentrations and discuss the geochemical behaviours of Ag, Pd and other trace and ultra-trace elements in the Estuary and Gulf of St. Lawrence (EGSL). We highlight the contrasting mixing behaviours of these elements, i.e., conservative (Cd, Re) vs. non-conservative (Ag, Pd), in samples collected during the winter and under ice-covered conditions. We ascribe the contrasting geochemical behaviour of these elements to their differential affinity for reactive surfaces carried into the estuary from the frozen watersheds. We also report an increase of the concentrations of Ag (up to 40 pmol L−1), Pd (up to 10 pmol L−1) and Pt (up to 0.4 pmol L−1) in the bottom and oxygen-depleted waters of the Gulf of St. Lawrence (GSL). A strong correlation between dissolved Pt concentrations and the stable carbon isotopic composition of the dissolved inorganic carbon (δ13C-DIC) suggests that the increased mobility of Pt may result from the aerobic mineralization of organic carbon or the oxidation of Pt-bearing organic complexes. Molar Pt/Pd ratios in the three water masses that compose the water column in the EGSL highlight a potential influence of anthropogenic sources near urban centers. The signature of continental end-members will be required to confirm the impacts of road traffic on the estuarine geochemistry of these elements.

Wastewater Treatment Using High-Performance In Situ Formed Double-Heterojunction Janus Photocatalyst Microparticles Shaped via a Microfluidic Device.

In this work, a heterogeneous photocatalysis system is fabricated for treating wastewater containing organic dyes and pharmaceutical substances. Double-heterojunction Janus photocatalysts are formed on the surface of size-tunable polydimethylsiloxane (PDMS) microparticles shaped via simple and low-cost coflow microfluidic devices. Ag0/Ag0-TiO2/TiO2 Janus-like photocatalysts are synthesized on the surface of porous PDMS microparticles as the support in which the metal-semiconductor heterojunction of Ag0/Ag0-TiO2 and the second heterojunction of Ag0-TiO2/TiO2 are created in situ, leading to the formation of Ag0/Ag0-TiO2/TiO2@PDMS photocatalysis systems. To form the heterojunctions on the PDMS surface, the polymer chain etching method is employed as a desired strategy to have half of the TiO2 nanoparticles on the surface of microparticles, which are treated by a Ag source. Using salt additives and the etching method, PDMS microparticles are made porous, providing more surface area for photoreactions. Surprisingly, the highest decomposition efficiencies of 94.4 and 91.1% are achieved for rhodamine B(RhB) and tetracycline (TC), respectively, under visible light for 60 min pH 11, a light source at a distance of 2 cm, 5 mM AgNO3, 10 wt % TiO2, 7 wt % NaCl, and 20 gm/L photocatalyst, which are conditions that result in the best performance for RhB degradation. Regarding the stability of the photocatalysts, no significant change is observed in the performance after five cycles.

Synthesize and characterization of silver coated Ti powders from waste titanium chips by mechanical milling assisted electroless plating method

This study used an electroless silver (Ag) coating method on Ti powders obtained from waste turnings using mechanical milling, a recycling technique. Various parameters of Ag source and reducing agent ratios were utilized in the Ag coating processes. The results demonstrated that increasing the silver source and reducing agent ratios resulted in a more homogeneous and thicker Ag coating layer on Ti powders. The rise in the reduced silver ratio resulted in an increase in crystallite size compared to untreated particles, which was attributed to the reduction of residual dislocations in Ti through the presence of Ag. The amount of silver on silver-coated Ti powders ranged from 12.49 wt% to 24.4 wt%. Furthermore, an increase in the silver ratio significantly enhanced the oxidation resistance properties. The mass change with oxidation obtained from TGA analysis reduced from 26.31 wt% to 14.88 wt% with increasing silver coating layer on Ti powders.

Mantis shrimp appendages-inspired Ag-CuO contact: Synergistically enhancing the erosion and impact resistance via gradient-layered scatter-island/chain-skeleton structure

Materials degradation induced by repeated arc erosion and impact poses a considerable challenge for Ag-based contacts. Fortunately, nature has evolved efficient strategies to construct complex gradient-layered structure that exhibit exceptional erosion and impact resistance. Drawing inspiration by the mantis shrimp appendages, a chain-like CuO nanofibre-reinforced Ag-CuO contact material with a gradient-layered scatter-island/chain-skeleton structure was designed and fabricated. Employing a combined experimental and simulation approach, the evolution of the microstructure during the erosion process was investigated. Results indicated that the interaction between the mantis shrimp appendage-like structure and the chain-like CuO nanofibres effectively suppressed the formation of cracks and pores on the contact surface. Particularly, the scatter-island layer not only played a crucial role in maintaining the viscosity of the molten pool and establishing stable electrical and thermal pathways, but also functioned as a “supplement” to continuously supply a steady source of Ag onto the molten pool surface, effectively promoting CuO skeleton restructuring. Meanwhile, the CuO skeleton diffusive-continuous restructuring of the chain-skeleton layer restricted molten pool flow, significantly enhancing contact erosion resistance. Furthermore, the strong synergistic effect between the gradient-layered structures dispersed stress and deformation concentration on the contact surface. It effectively delayed the defects formation and suppressed interfacial debonding, thereby endowing the contact with excellent impact resistance. Our work presents a fascinated route for designing novel biomimetic Ag-based contacts.

Development of super nanoantimicrobials combining AgCl, tetracycline and benzalkonium chloride

In this work, we demonstrate that a simple argentometric titration is a scalable, fast, green and robust approach for producing AgCl/antibiotic hybrid antimicrobial materials. We titrated AgNO3 into tetracycline hydrochloride (TCH) aqueous solution, thus forming AgCl/TCH in a one-step procedure. Furthermore, we investigated the one-pot synthesis of triply synergistic super-nanoantimicrobials, combining an inorganic source of Ag+ ions (AgCl), a disinfecting agent (benzyl-dimethyl-hexadecyl-ammonium chloride, BAC) and a molecular antibiotic (tetracycline hydrochloride, TCH). Conventional antimicrobial tests, industrial biofilm detection protocols, and in situ IR-ATR microbial biofilm monitoring, have been adapted to understand the performance of the synthesized super-nanoantimicrobial. The resulting hybrid AgCl/BAC/TCH nanoantimicrobials are found to be synergistically active in eradicating Salmonella enterica and Lentilactobacillus parabuchneri bacteria and biofilms. This study paves the way for the development of a new class of super-efficient nanoantimicrobials that combine relatively low amounts of multiple active species into a single (nano)formulation, thus preventing the development of antimicrobial resistance towards a single active principle.

Removal of iodide from aqueous solutions using a silver-modified ZnAl layered double hydroxide

The removal of radioactive iodine from aqueous solutions is of great concern due to its high environmental mobility and toxicity. To improve the removal ability of layer double hydroxide (LDH) for iodide (I−), Ag-modified Zn3Al1-LDH (Ag@Zn3Al1-LDH) was prepared, characterized, and applied as an adsorbent for I−. Results indicated that the silver was included in Zn3Al1-LDH hybrid materials in the form of Ag2CO3, Ag2O, and Ag (0) nanoparticles and that the Ag contents in the Ag@Zn3Al1-LDH could be easily controlled by the amounts of Ag source added in the synthesis process. The Ag@Zn3Al1-LDH exhibited high adsorption capacity to iodide, and the adsorption capacity of the sample containing 12.2 wt% Ag was as high as 256.0 mg/g, which is 35.6 times higher than that of Zn3Al1-LDH. Furthermore, the Ag@Zn3Al1-LDH exhibited high selectivity for iodide and could function in a wide range of pH. Iodide was removed through cooperative effects mechanisms including the chemical adsorption of Ag2O and Ag2CO3, ion exchange of Zn3Al1-LDH, and the surface complexation of Zn3Al1-LDH for iodide. This work indicated that Ag@Zn3Al1-LDH could be a potentially efficient material for the removal of iodide from wastewater.

Intense pulsed light annealing of solution-based indium–gallium–zinc–oxide semiconductors with printed Ag source and drain electrodes for bottom gate thin film transistors

In this study, an intense pulsed light (IPL) annealing process for a printed multi-layered indium–gallium–zinc–oxide (IGZO) and silver (Ag) electrode structure was developed for a high performance all-printed inorganic thin film transistor (TFT). Through a solution process using IGZO precursor and Ag ink, the bottom gate structure TFT was fabricated. The spin coating method was used to form the IGZO semiconductor layer on a heavily-doped silicon wafer covered with thermally grown silicon dioxide. The annealing process of the IGZO layer utilized an optimized IPL irradiation process. The Ag inks were printed on the IGZO layer by screen printing to form the source and drain (S/D) pattern. This S/D pattern was dried by near infrared radiation (NIR) and the dried S/D pattern was sintered with intense pulsed light by varying the irradiation energy. The performances of the all-printed TFT such as the field effect mobility and on–off ratio electrical transfer properties were measured by a parameter analyzer. The interfacial analysis including the contact resistance and cross-sectional microstructure analysis is essential because diffusion phenomenon can occur during the annealing and sintering process. Consequently, this TFT device showed noteworthy performance (field effect mobility: 7.96 cm2/V s, on/off ratio: 107). This is similar performance compared to a conventional TFT, which is expected to open a new path in the printed metal oxide-based TFT field.

Electrosynthesis and Characterizations of Aluminum Silver Selenide (Alagse2), Thin Films for Possible Device Applications

The semiconductor thin films of Aluminum Silver selenide (AlAgSe2) have been successfully deposited onto FTO glass substrate using electrodeposition method. AgNO3, AlCl3.6H2O and Selenium powder were the precursors used for sources of Ag, Al and Se ions respectively. Prototype of the films were again made and subjected to annealing at temperature of 150°C for 5 minutes to remove the element of moisture content in the as deposited films. The properties of the films such as optical, structural and compositional were investigated using UV-VIS Spectrophotometry, X-ray diffractometry and Rutherford Backscattering Spectroscopy (RBS) analysis respectively to determine the possible areas of applications of the films. Optical analysis revealed that the films have high absorbance in the UV region but decreased in the visible and near infrared regions. The increase in the concentration of selenide ions however decrease the absorbance of the films but annealing tends to increases the absorbance. The films also exhibited very high values of refractive index with minimum value in the order of 2.0 for both the annealed and as deposited samples. The bandgap energies of the films were found to be 1.7 eV, 1.8 eV, 2.2 eV, 2.8 eV and 2.9 eV for as deposited, but decreased to the values of 1.5 eV, 1.6 eV, 1.92 eV, 2.15 eV and 2.5 eV after annealing for the films deposited with 0.1 M, 0.2 M, 0.3 M, 0.4 M and 0.5 M Se ions respectively. The structural analysis indicates that AlAgSe2 films are crystalline in nature with most preferential crystalline plane of (112). The RBS compositional analysis showed that the deposited thin films are rich in silver content. These properties exhibited by the deposited thin films of AlAgSe2 are desirable for photovoltaic devices and for many other optical and optoelectronic applications.

Silver Behavior During Magmatic and Magmatic-Hydrothermal Evolution of a Highly Evolved Reduced Granitic System Related to the Giant Shuangjianzishan Ag-Pb-Zn-(Sn) Epithermal Deposit, Northeast China

Abstract Magmatic-related epithermal silver-rich polymetallic deposits are among the most important sources of Ag in the world, and they are found associated with magmatic systems with striking differences. Most of the time, they are associated either with I-type oxidized (magnetite-series granite) intermediate to evolved intrusions or with S-type/A-type reduced (ilmenite-series granite) highly evolved intrusions. To better understand these associations, the Ag evolution has been tracked during the magmatic differentiation and the magmatic-hydrothermal transition stage of A-type highly evolved porphyritic granites associated with the giant Shuangjianzishan Ag-Pb-Zn-(Sn) epithermal deposit, the largest known Ag deposit of Asia (145 million tonnes at 128.5 g/t Ag and 2.2 wt % Pb + Zn) located in the largest known metallogenic province for Ag in China (the southern Great Xing’an Range). At the Shuangjianzishan deposit, the porphyritic granite complex consists of three temporally distinct intrusions—a coarse-grained monzogranite porphyry, a fine-grained syenogranite porphyry, and a fine-grained syenogranite—having crystallized at ~2 kbar and ~750°C and recording a continuous magmatic differentiation trend. The silicate melt that generated the last highly differentiated intrusion (fine-grained syenogranite) is interpreted as the source of the mineralizing fluids forming the Shuangjianzishan Ag-Pb-Zn-(Sn) epithermal deposit, as it is the only intrusive unit that reached fluid saturation, as indicated by cotrapped fluid and melt inclusions in quartz phenocrysts and by the occurrences of unidirectional solidification textures (USTs). Silver evolution in the different porphyritic granite facies was reconstructed with laser ablation-inductively coupled plasma-mass spectrometry analyses of quartz-hosted silicate melt inclusions, amphibole-hosted magmatic sulfide inclusions, and chemical modeling. The silicate melt forming the porphyritic granite complex was sulfide saturated during the first crystallization stage, as shown by the occurrence of Ag-rich monosulfide solid solution (MSS) inclusions hosted in amphibole phenocrysts from the coarse-grained monzogranite porphyry and from mafic microgranular enclaves hosted in the coarse-grained monzogranite porphyry. However, these Ag-rich MSSs had only a minimal impact on the Ag budget of the magmatic system, as shown by the increase of the Ag concentration (~100–1,000 ppb) in quartz-hosted silicate melt inclusions during the further evolution of the system until fluid exsolution was reached. These results combined with mass balance modeling suggest that Ag and Sn are efficiently transferred to the evolving residual melt during crystallization and crystal-melt segregation. The results of this study indicate that highly Ag endowed epithermal polymetallic deposits can be formed from the exsolution of Ag-rich mineralizing fluids from relatively low volume, highly evolved, reduced melts, similar to those responsible for the formation of Sn-rich greisen deposits.

Extracellular biosynthesis and characterization of silver and zinc oxide nanoparticles using Pseudomonas aeruginosa and Escherichia coli

Abstract Background: The development of dependable and environmentally friendly nanomaterial resources is an essential aspect of recent nanotechnology research and application. Microorganisms have recently been investigated as a potential biofactor for the synthesis of many nanoparticles (NPs). Objectives: The aim of this article is to evaluate the extracellular biosynthesis capabilities of metallic NPs such as silver (Ag) and zinc oxide (ZnO) by screening common bacteria. Materials and Methods: Silver nitrate and zinc nitrate were used as a source of Ag and ZnO NPs, by means of Escherichia coli and Pseudomonas aeruginosa as potential candidates for the rapid synthesis of NPs. Ag and ZnO NPs were synthesized using a reduction of aqueous solutions with cell-free filtrates of bacteria. Characterization of synthesized NPs was conducted by UV–Vis spectroscopy. Results: Transmission electron microscopy (TEM) was used to examine the particle size of (Ag, ZnO) NPs. The maximum absorbance was around (425, 450 nm) for Ag and (300, 380 nm) for ZnO by E. coli and P. aeruginosa, respectively. We found that particle size of Ag NP obtained from P. aeruginosa was smaller than that of NP obtained from E. coli. The range of particle size was 24–32 nm with an average of 29.5 nm for Ag P. aeruginosa and was 25–37 nm with an average of 32 nm for Ag E. coli. The particle size range of ZnO of P. aeruginosa was 23–28 nm with an average of 25 nm and was 25–34 nm with an average of 29.7 nm for E. coli. Conclusion: E. coli and P. aeruginosa are good candidates for biosynthesis of NPs. As a result, obliged characteristics and green synthesis and the potential issue for various environmental and health-related applications may exist.

Demonstration of Feasibility Using Ionic Liquid as Electrolyte for Electrochemical Deposition and Recovery of Silver from Silver Oxide

Silver oxide (Ag₂O) is soluble in the hydrophobic protic amide-type ionic liquid (IL), protonated-betaine bis((trifluoromethyl)sulfonyl)amide ([Hbet][TFSA]). Cyclic voltammetric behavior of Ag(I) showed a single redox couple, and NMR spectra implied that Ag⁺ might be coordinated with the [TFSA] anions in more extent than with the deprotonated [Hbet] ions (i.e. [bet]; a Zwitterion). By changing the scan rates and cycle numbers of potential scan utilized for the cyclic voltammetric electrodeposition, different particle sizes and distribution densities of silver nanoparticles (AgNPs) could be electrodeposited on glassy carbon disc electrode (GCE), which showed activities towards the electrochemical reduction of nitrate and oxidation of hydrazine, respectively, in alkaline solutions. The high faradic efficiencies (F.E.) of Ag electrodeposition using the contents of Ag₂O coin batteries as the Ag source implied that it may be possible to develop a process for recovering Ag from spent Ag₂O coin batteries based on the electrochemical system reported here.

Bright Red Luminescence from Ag–In–Ga–S-Based Quantum Dots with the Introduction of Copper

Abstract This study presents cadmium-free, red-emission quantum dots (QDs) synthesized by incorporating Cu into silver indium gallium sulfide/gallium sulfide (Ag–In–Ga–S/Ga–S) core/shell QDs. By using a previous technique, in which the original Ag–In–Ga–S/Ga–S core/shell QDs exhibiting band-edge photoluminescence (PL) were improved to achieve a narrower emission and facile synthesis, we injected a mixture of Cu and Ag sources into a heated solution containing In, Ga, and S sources. This resulted in the formation of Ag–Cu–In–Ga–S quinary QDs without any precipitation. After being coated with a Ga–S shell, these QDs exhibit a red PL with a spectral full-width at half maximum of 55–60 nm. Although the PL wavelength was responsive to changes in In/Ga ratios, it was unaffected by variations in Cu/Ag ratios due to the transition between conduction band electrons and holes localized at Cu cites. Notably, the electroluminescence device exhibited high-purity red light that satisfies the recommendation ITU-R BT.2020 standard.

Silver isotopes: A tool to trace smelter-derived contamination

Here, for the first time, we report the concentrations and isotopic data of Ag in a variety of ore and metallurgical samples and forest soils that have been polluted due to Ag–Pb smelter emissions. Similar to the Ag concentrations, we identified a large range of δ109Ag values (from −0.8 to +2.4‰), a ∼3‰ spread, within the primary and secondary materials (i.e., galena, fly ash, slag and matte). This phenomenon, however, is evidently unrelated to Ag isotopic fractionation during the smelting process, but it reflects the starting 109Ag/107Ag signal in ore mineral and/or the specific type of ore genesis. The two studied soil profiles differed in Ag isotopic composition, but on the other hand, they consistently showed significantly lighter Ag (≤+0.8‰) of metallurgical origin in the upper horizons compared to the bottom horizons and bedrocks, with low Ag amounts depleted of 107Ag (≤+2.9‰). This isotopic pattern can be attributed to a ternary mixing relationship involving two major anthropogenic Ag components and a minor contribution from geogenic Ag. Accordingly, we did not observe any post-depositional isotopic fractionation in our soils, since Ag was geochemically stable and it was not subjected to leaching. In summary, the Ag isotopes have a potential to trace variations in anthropogenic phases, to monitor specific geochemical processes, and are clearly applicable as anthropogenic Ag source and Ag load proxies.

Analysis of polyisoprene oligomers via in situ silver nanoparticle formation on thin-layer chromatography plate using matrix-assisted laser-induced desorption/ionization mass spectrometry.

The direct mass spectrometry (MS) detection of polyisoprene (PI) oligomers on a thin-layer chromatography (TLC) plate using matrix-assisted laser-induced desorption/ionization (MALDI) with silver trifluoroacetate as the cationization reagent was investigated. The spots of PI oligomers and silver trifluoroacetate on the TLC plate resulted in brown materials after UV laser irradiation. It was suggested that silver trifluoroacetate yielded Ag nanoparticles as brown materials after heating via laser irradiation. The nanoparticles behaved as an inorganic matrix and a source of Ag+ adduct in the analysis of PI oligomers. The use of organic matrices together with silver trifluoroacetate reduced the signal intensity of PI oligomers on MALDI-MS on a TLC plate. The separation of PI oligomers (polymerization degree, n = 5-11) by TLC resulted in a single elliptical spot without a clear separation after the chromatographic procedure. However, in MS imaging, differences in migration lengths based on degrees of polymerization were clearly observed and the degrees of polymerization were identified without comparison with standards.

Comparative study of conventional and synchrotron X-ray electron densities on molecular crystals.

Five different electron density datasets obtained from conventional and synchrotron single crystal X-ray diffraction experiments are compared. The general aim of the study is to investigate the quality of data for electron density analysis from current state-of-the-art conventional sources, and to see how the data perform in comparison with high-quality synchrotron data. A molecular crystal of melamine was selected as the test compound due to its ability to form excellent single crystals, the light atom content, and an advantageous suitability factor of 3.6 for electron density modeling. These features make melamine an optimal system for conventional X-ray diffractometers since the inherent advantages of synchrotron sources such as short wavelength and high intensity are less critical in this case. Data were obtained at 100 K from new in-house diffractometers Rigaku Synergy-S (Mo and Ag source, HyPix100 detector) and Stoe Stadivari (Mo source, EIGER2 1M CdTe detector), and an older Oxford Diffraction Supernova (Mo source, Atlas CCD detector). The synchrotron data were obtained at 25 K from BL02B1 beamline at SPring-8 in Japan (λ = 0.2480 Å, Pilatus3 X 1M CdTe detector). The five datasets were compared on general quality parameters such as resolution, ⟨I/σ⟩, redundancy and R factors, as well as the more model specific fractal dimension plot and residual density maps. Comparison of the extracted electron densities reveals that all datasets can provide reliable multipole models, which overall convey similar chemical information. However, the new laboratory X-ray diffractometers with advanced pixel detector technology clearly measure data with significantly less noise and much higher reliability giving densities of higher quality, compared to the older instrument. The synchrotron data have higher resolution and lower measurement temperature, and they allow for finer details to be modeled (e.g. hydrogen κ parameters).

Distribution and sources of Ag, Au, Bi, Cu and Mo in surface soils. Case study: Mitrovica region, Republic of Kosovo

The objective of this study was to investigate the spatial distribution and content of a specificanthropogenic group of trace metals (Ag, Au, Bi, Cu and Mo) in surface soils (0 - 5 cm) of the Mitrovicaregion, Republic of Kosovo. The content of metals was determined by inductively coupled plasma - massspectrometry (ICP-MS). The average content of Cu (42 mg/kg), Bi (1.5 mg/kg), Ag (0.44 mg/kg) and Au(2.7 μg/kg) exceeded the average content of metals in European and world soils by 3.4 and 1.4 times, 3.0and 7.5 times, 1.62 and 8.8 times and 2.7 and 1.8 times, respectively. The average Mo content of 0.68 mg/kgexceeded the mean Mo content in European soil by 1.09 times, while the mean content in world soils wasnot exceeded. Copper levels were also found to exceed the Dutch target value of 36 mg/kg in 152 km2 andthe Dutch action value of 190 mg/kg on 6.2 km2 of the 301.5 km2of the study area. The values of theenrichment factor (EF) for the analyzed elements are all above 1.5, indicating that their higher content is ofanthropogenic origin, mainly due to lead and zinc mining and metallurgical activities in the study area. Thequality of the soils in the Mitrovica region varies from heavily contaminated with copper and bismuth, withextremely high enrichment of Cu, Bi and Ag in the soils of the central zone (Zone I) and the urban soils ofthe cities of Zveçan and Mitrovica.

Nanoscale Whole-Body Expansion Microscopy Revealed the Early Skeletal Developmental Malformation Induced by Silver Nanoparticles

The widely used silver nanoparticles (AgNPs) can cause damage to skeletal development in aquatic organisms, which has a significant impact on their survival and reproduction. We hypothesized that the biological toxicity of AgNPs itself may be the culprit for early skeletal developmental malformation. In this study, we achieved the first nanoscale visualization of the notochord and skeletal muscle anatomy affected by exposure to AgNPs through a novel whole-body expansion microscopy technique (whole-ExM). This technique allows the whole zebrafish to be expanded equally in three dimensions by ∼4.5 times, enabling nanoscale resolution imaging without complex and expensive equipment. Our results suggested that AgNPs caused curvature deformation of the notochord as well as reduced and loosely arranged skeletal muscle. In addition, we demonstrated that the main source of Ag+ was the dissolution of AgNPs in vivo. Compared with that of the released Ag+, the developmental toxicity caused by AgNPs themselves was non-negligible. This work achieved cellular-level visualization of living animals and overcame the limitations of previous macroscopic or microscopic consideration of the toxicity of AgNPs. The study provided a new perspective for assessing the toxicity of nanomaterials by using whole-ExM to achieve ultraclear nanoscale imaging of biological organs.

Dielectric barrier discharge plasma synthesis of Ag/γ-Al2O3 catalysts for catalytic oxidation of CO

In this study, Ag/γ-Al2O3 catalysts were synthesized by an Ar dielectric barrier discharge plasma using silver nitrate as the Ag source and γ-alumina (γ-Al2O3) as the support. It is revealed that plasma can reduce silver ions to generate crystalline silver nanoparticles (AgNPs) of good dispersion and uniformity on the alumina surface, leading to the formation of Ag/γ-Al2O3 catalysts in a green manner without traditional chemical reductants. Ag/γ-Al2O3 exhibited good catalytic activity and stability in CO oxidation reactions, and the activity increased with increase in the Ag content. For catalysts with more than 2 wt% Ag, 100% CO conversion can be achieved at 300 °C. The catalytic activity of the Ag/γ-Al2O3 catalysts is also closely related to the size of the γ-alumina, where Ag/nano-γ-Al2O3 catalysts demonstrate better performance than Ag/micro-γ-Al2O3 catalysts with the same Ag content. In addition, the catalytic properties of plasma-generated Ag/nano-γ-Al2O3 (Ag/γ-Al2O3-P) catalysts were compared with those of Ag/nano-γ-Al2O3 catalysts prepared by the traditional calcination approach (Ag/γ-Al2O3-C), with the plasma-generated samples demonstrating better overall performance. This simple, rapid and green plasma process is considered to be applicable for the synthesis of diverse noble metal-based catalysts.

Facile High-Yield Synthesis of Ag–In–Ga–S Quaternary Quantum Dots and Coating with Gallium Sulfide Shells for Narrow Band-Edge Emission

Among cadmium-free quantum dots (QDs), ternary or quaternary chalcogenide semiconductor QDs composed of groups 11, 13, and 16 elements have extensively been studied. Herein, monodispersed quaternary nanoparticles of silver indium gallium sulfide (AgInxGa1–xS2) are synthesized by a new route that specifically produces the target product without solid byproducts. The difference in the reactivity between groups 11 and 13 metals with chalcogen is a common issue in synthesizing the groups 11, 13, and 16 ternary or quaternary semiconductor QDs. Instead of a common approach to suppress the reactivity of group 11 metals, this study utilizes their high reactivity; rapid injection of a Ag source into the solution containing a thiocarboxylate produced small Ag2S nanoparticles. These Ag2S nanoparticles are then exposed to indium-, gallium-, and sulfur-containing species in situ and then converted into quaternary nanoparticles comprising AgInxGa1–xS2. Due to the well-controlled reaction steps, the product yield based on Ag was increased to 60%, which significantly exceeds that obtained using our previous approach of heating all-mixed raw materials (5–15%). After coating with gallium sulfide (GaSy) shells, the core/shell QDs exhibited an intense, green-colored band-edge emission with a tunable peak wavelength between 499 and 543 nm. The excellent uniformity of the core nanoparticles in terms of size and composition demonstrated a quite narrow band-edge emission with the full width at half maximum of 31 nm, which is equal to the record-narrow values of green-emitting cadmium-free QDs. Additionally, a near-unity photoluminescence quantum yield was achieved after postsynthetic surface treatment by alkylphosphines, indicating the defect-free nature of the prepared AgInxGa1–xS2/GaSy core/shell QD system.