Amounts Of Ag Nanoparticles Research Articles

Cellular uptake of metal oxide-based nanocomposites and targeting of chikungunya virus replication protein nsP3

Emergence of new pathogenic viruses along with adaptive potential of RNA viruses has become a major public health concern. Therefore, it is increasingly crucial to investigate and assess the antiviral potential of nanocomposites, which is constantly advancing area of medical biology. In this study, two types of nanocomposites: Ag/NiO and Ag2O/NiO/ZnO with varying molar ratios of silver and silver oxide, respectively have been synthesised and characterised. Three metal/metal oxide (Ag/NiO) composites having different amounts of Ag nanoparticles (NPs) anchored on NiO octahedrons are AN-5 % (5 % Ag), AN-10 % (10 % Ag) and AN-15 % (15 % Ag)) and three ternary metal oxide nanocomposites (Ag2O/NiO/ZnO) i.e., A/N/Z-1, A/N/Z-2, and A/N/Z-3 with different molar ratios of silver oxide (10 %, 20 % and 30 %, respectively) were evaluated for their antiviral potential. Cellular uptake of nanocomposites was confirmed by ICP-MS. Intriguingly, molecular docking of metal oxides in the active site of nsP3 validated the binding of nanocomposites to chikungunya virus replication protein nsP3. In vitro antiviral potential of nanocomposites was tested by performing plaque reduction assay, cytopathic effect (CPE) analysis and qRT-PCR. The nanocomposites showed significant reduction in virus titre. Half-maximal inhibitory concentration (IC50) for A/N/Z-3 and AN-5 % were determined to be 2.828 and 3.277 µg/mL, respectively. CPE observation and qRT-PCR results were consistent with the data obtained from plaque reduction assay for A/N/Z-3 and AN-5 %. These results have opened new avenues for development of nanocomposites based antiviral therapies.

Ag nanoparticles anchored on NiO octahedrons (Ag/NiO composite): An efficient catalyst for reduction of nitro substituted phenols and colouring dyes

The development of an efficient sustainable catalyst for effective removal of hazardous chemicals, viz. nitrophenols and organic dyes, from wastewater is a challenging task. Herein, facile synthesis of Ag/NiO composites by anchoring Ag nanoparticles (NPs) on NiO octahedrons with different amounts of Ag NPs (AN-5% (5% Ag), AN-10% (10% Ag) and AN-15% (15% Ag)) has been demonstrated. SEM (scanning electron microscopic) and TEM (transmission electron spectroscopic) images ensured the proper anchoring of spherical Ag NPs (particle size = 16.54 ± 1.88 nm) on octahedron particles of NiO, which was also ensured by XPS (X-ray photoelectron spectroscopy) analysis. Moreover, the resulting composites have an average surface area (49–52 m2g‒1) and pore size (2.39–2.26 nm). All three synthesized Ag/NiO composites (100 μL) catalyzed the complete reduction of para-np (4-nitrophenol: 0.1587 mM) within 2–3 min in the presence of 0.04 M NaBH4. Among them, AN-5% has been chosen because of the lowest anchored Ag (5%) to obtain the optimized catalyst's amount (50 μL) and concentration of para-np (0.1587 mM). AN-5% also exhibited excellent catalytic activity towards different nitro substituted phenols, viz. ortho-np (2-nitrophenol), meta-np (3-nitrophenol), para-np (4-nitrophenol) and tri-np (2,4,6-trinitrophenol). AN-5% displayed ∼100% catalytic efficiency for reducing meta-np in 2 min with the apparent first order rate constant (kapp) and normalized rate constant (Knor) as 1.99 s−1 and 398.14 s−1 g−1, respectively. Additionally, AN-5% (29.41 μg mL−1) reduced >95% of the colouring dyes (10 ppm) such as CONG-R (congo red: 95% in 6 min), METH-O (methyl orange: 97.5% in 7 min), METH-B (methylene blue: 98.3% in 10 min) and RHOD-B (rhodamine B: 99.2% in 5 min). AN-5% not only demonstrated catalytic reduction towards individual pollutants, but also showed excellent activity for reduction of the mixtures of nitrophenols/dyes and for treatment of simulated industrial effluent samples (EFF1, EFF2) and a real industrial sample (textile dye-bath effluent). AN-5% can also be reused up to several cycles with almost same efficiency and followed the Langmuir-Hinshelwood apparent first order kinetics model.

Room Temperature Methanol Sensors Based on Rod-Shaped Nanostructures of MoS2 Functionalized With Ag Nanoparticles

In this work, molybdenum sulfide (MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) nanostructures were prepared by a hydrothermal method to detect methanol vapor. The effect of adding different amounts of Ag nanoparticles (0.5wt%, 1wt%, 2wt%, 2.5wt%, and 5wt%) to MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> on the response of sensors was investigated. All sensors could suitably detect methanol at room temperature. The response of sensors based on pure MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and MoS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /Ag (2wt%) to 100 ppm of methanol was 7.1% (lowest response) and 21.6% (highest response), respectively. It was found that adding Ag nanoparticles greatly increases both sensitivity and selectivity. The structural, morphological, and composition properties of the prepared materials were approved by XRD, SEM, TEM, and EDX techniques. As another advantage, the proposed sensors can be easily recovered in the air at room temperature without the need for additional energy. By exposing the sensors to three successive cycles of methanol/air as well as testing them within 6 weeks, it was found that the sensors have good repeatability and chemical stability. By examining the response to different analytes, it was found that the sensors can selectively detect methanol with high sensitivity. Therefore, our low-cost (PCB-based) sensors are suitable options for the preferable detection of methanol in different industries.

Facile fabrication of Ag decorated TiO2 nanorices: Highly efficient visible-light-responsive photocatalyst in degradation of contaminants

In this report, TiO2 nanorices were synthesized by solvothermal method and the effect of deposition of silver nanoparticles on the photocatalytic behaviour of synthesized TiO2 was investigated carefully. XRD pattern showed that the dominant phase of synthesized TiO2 is Rutile. SEM images and EDX analysis illustrated nanorice structure of TiO2 as well as the existence of silver nanoparticles. TEM images displayed that the AgNPs are just uniformly located on the surface of TiO2 nanorices. Diffuse Reflectance Spectroscopy (DRS) demonstrated the obvious plasmonic effect of silver nanoparticles and Photoluminescence Spectroscopy proved the increasing of recombination time caused by silver nanoparticles deposition. Photocatalytic activity of the prepared samples with various amounts of Ag nanoparticles was extensively investigated. TiO2 sample with 0.125% Ag showed the best photocatalytic activity to degradation of Acid Blue 92 and Crystal Violet as pollutant model materials. Using this photocatalyst, degradation amount of Acid Blue 92 and Crystal Violet are 72% and 53.16% after 90 min with 0.0139 min−1 and 0.008 min−1 rate constant, respectively. The as-synthesized nanostructure showed appropriate stability due to the results of recycling tests and TEM images.

Plasmonic effects of quantum size metal nanoparticles on dye-sensitized solar cell

Gel polymer electrolytes (GPEs) based on poly(ethylene oxide) (PEO) and phthaloyl chitosan (PhCh) for dye-sensitized solar cells (DSSCs) have been synthesized and characterized. The GPEs have been prepared using different weight fractions of PEO and PhCh that have been added to a fixed composition solution of tetrapropylammonium iodide (TPAI), dimethylformamide (DMF) and iodine (I-2) crystals. The ionic conductivity behavior of prepared GPEs was studied using impedance spectroscopy. The sample having 70 wt.% PEO and 30 wt.% PhCh showed the highest ionic conductivity of 7.36 mS cm(-1) at room temperature. The photoanode of the DSSC consists of two TiO2 layers. The first or compact layer has a thickness of similar to 5 mu m and the TiO2 nanoparticles have an average size of 14 nm. The second layer of TiO2 nanoparticles has an average size of 21 nm. In order to adsorb dye molecules, the TiO2 photoanodes were soaked in anthocyanin and ruthenium 535 (N3) dye solutions. The GPE has been deposited between the dye/ TiO2 photoanode and platinum (Pt) counter electrode in a sandwich-like structure. Results showed that the fabricated DSSC with an electrolyte containing 70 wt.% PEO: 30 wt.% PhCh exhibited the highest efficiency for both anthocyanin and N3 dyes and the efficiency and ionic conductivity trend versus PEO content are similar. On addition of different amounts of Ag nanoparticles (0, 10, 20, 30, 40 mu L), with average size of 10 nm to the second TiO2 layer, the performance of DSSCs with anthocyanin sensitizer and N3 dye improved. The cell with anthocyanin/(TiO2 + 10 mu L Ag nanoparticles) showed a 21%, 17.2% and 39.6% increase in short circuit current density (J(sc)), fill factor (FF), and light to electricity conversion efficiency (.) respectively compared to the cell without Ag nanoparticle. The DSSC fabricated with TiO2 photoanode containing 20 mu L Ag nanoparticles soaked in N3 dye exhibits Jsc, FF, and. of 15.24 mA cm(-2), 57% and 5.21% respectively. The incorporation of Ag nanoparticles has resulted in a 17% and 13% increase in Jsc, and., respectively, for N3 based cells. This performance enhancement with the addition of Ag nanoparticles can be attributed to improvement of light scattering and charge transport as a result of plasmonic resonance.

Toughening of Alumina Ceramics with Silver Nanoparticles

In this study ceramic materials with an Al 2O3-matrix toughened with different amounts of Ag nanoparticles (0.0, 0.5, 1.0, 2.0 and 3.0 wt. %) were fabricated. High energy milling was used to mix the materials in a planetary mill t ype, in which powder particles with sizes of ~300nm were obtained. With the milled powders, they were fabricated cylindrical samples by uniaxial pressing. Then, compacted samples were sintered in an electrical furnace at different temperatures (1400°C, 1500°C a nd 1600°C) and during different times (1, 2 and 3h). Microstructure observations were mad e with optical microscopy and scanning electron microscopy, observing in both cas es dense composites with very fine microstructures. Concerning the measurement results of fracture toughness, which were estimated by the indentation fracture method, it wa s shown that the composites made by mean procedure present higher values than the avera ge of the monolithic alumina, up to 400%. It was determined that the reinforcement mechanism of these materials is due to the deflection of cracks owing to metallic bridges form ed by the silver used as alumina strengthener.

Enhanced ferroelectric photoelectrochemical properties of polycrystalline BiFeO3 film by decorating with Ag nanoparticles

Polycrystalline BiFeO3 (BFO) films are fabricated on Pt/Ti/SiO2/Si(100) substrate as photoelectrode using sol-gel method. The microstructure, optical, and photoelectrochemical (PEC) properties of the films are characterized and optimized by controlling the film thickness. Moreover, the PEC properties of the BFO films are dependent on ferroelectric polarization, which is mainly ascribed to the modulation of band structure at the BFO/electrolyte interface by the polarization. Further enhancement of PEC properties is obtained by decorating the samples with appropriate amounts of Ag nanoparticles, which is attributed to the reduced electron-hole recombination, and localized surface plasmon resonance effect of Ag nanoparticles.

Synthesis of Ag–ZnO with multiple rods (multipods) morphology and its application in the simultaneous photo-catalytic degradation of methyl orange and methylene blue

In this study, the photo-decolorization of a mixture of methylene blue (MB) and methyl orange (MO) was investigated using Ag–ZnO multipods. The photo-catalyst used, ZnO multipods, was successfully synthesized. The surface of ZnO microstructure was modified by deposition of different amounts of Ag nanoparticles (Ag NPs) using the photo-reduction method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis and atomic absorption spectroscopy. The photo-catalytic efficiency of Ag–ZnO is mainly controlled by the amount of Ag NPs deposited on the ZnO surface. The results obtained suggest that Ag–ZnO containing 6.5% Ag NPs, has the highest photo-catalytic performance in the simultaneous photo-degradation of dyes at a shorter time.

A general method to diverse silver/mesoporous–metal–oxide nanocomposites with plasmon-enhanced photocatalytic activity

Incorporating plasmonic Ag nanoparticles into mesoporous metal–oxide (MMO) semiconductors will achieve collective effect to greatly increase the photocatalysis. This work demonstrated a general two-step method to obtain diverse Ag/MMO composite photocatalysts with plasmon-enhanced photocatalytic activity. Several typical MMO (TiO2, ZnO, and CeO2) semiconductors were synthesized by integrating evaporation-induced self-assembly and in situ pyrolysis of metal precursors. Different amounts of Ag nanoparticles were then loaded in these MMO semiconductors through a facile photodeposition process. The Ag nanocrystals with sizes of 50–100nm were embedded in MMO semiconductors, endowing the Ag/MMO composites notable visible light absorption. The photocatalytic activities of the as-prepared diverse photocatalysts were studied systematically. The influencing factors including MMO species, mesoporous structure, and Ag loading amount on the photocatalytic activity were discussed in detail. The Ag/MMO composites exhibited much improved photocatalytic activity than their pure MMO semiconductors. The mesoporous TiO2 with the Ag-loading amount of 5wt.% exhibited the best photocatalytic performance for photodegrading both methylene blue and phenol under a simulated sunlight. The enhancement in photocatalysis is attributed to the synergistic effect of the mesoporous structures for efficient mass transfer as well as the Ag nanoparticles providing plasmonic enhanced light absorption.

Enhanced noble gas adsorption in Ag@MOF-74Ni

Various amounts of Ag nanoparticles were successfully deposited in porous MOF-74Ni (or Ni/DOBDC) by an auto-reduction method. An optimized silver-loaded MOF-74Ni was shown to have an improved Xe adsorption capacity (15% more) at STP compared to the MOF without silver nanoparticles. The silver-loaded sample also has a higher Xe/Kr selectivity. These results are explained by the stronger interactions between polarizable Xe molecules and the well-dispersed Ag nanoparticles.

Increasing the effective work function of multilayer graphene films using silver nanoparticles

The authors report a practical method to increase the effective work functions of multilayer graphene (MLG) films for high work function transparent electrodes. MLG films were prepared using a chemical vapor deposition and transfer process. The effective work functions of MLG films covered with different amounts of silver (Ag) nanoparticles were measured using ultraviolet photoelectron spectroscopy (UPS). The formation of Ag nanoparticles on the MLG surface was investigated using scanning electron microcopy. The sheet resistance and transmittance of the MLG films were also measured with different amounts of Ag nanoparticles on the MLG surfaces. The UPS measurements revealed that the effective work function of an MLG film could be increased from 4.39 to 4.55 eV by adding Ag nanoparticles onto the MLG surface with minimal changes in the sheet resistance and transmittance.

Ethanol Sensing Properties of Tin Oxide Doped Using Silver Nanoparticles

Composite powders of SnO2 with different amounts of Ag nanoparticles (0.3 wt%, 0.5 wt%, 0.8 wt% and 1.5 wt%) were prepared by reducing an aqueous silver nitrate solution with NaBH4 followed by washing and heating treatments. Gas sensors, based on both pure SnO2 and the prepared composite powders were fabricated by simple, reproducible and low cost method of powder pressing followed by sintering in air at 500oC for 2 hours. The morphology of the materials was characterized by XRD and SEM methods. The gas sensing performance of all sensors were examined in an ethanol vapor atmosphere. Both pure SnO2 and Ag/ SnO2 based sensors showed high responses to the ethanol vapor. However, in terms of response time and working temperature the Ag/SnO2 based sensors showed better performances, i.e. they worked at lower temperatures and responded at shorter times. The response time of all sensors was less than 6s; however, optimized performance was observed for the sensor with 1.5% Ag concentration, showing 99% responses at 260oC with a response time of 3s. The results showed that Ag nanoparticles doped in SnO2, effectively can increase sensor performance for ethanol detection.

Polydopamine as an intermediate layer for silver and hydroxyapatite immobilisation on metallic biomaterials surface

Hydroxyapatite (HA) coated implant is more susceptible to bacterial infection as the micro-structure surface which is beneficial for osseointegration, could also become a reservoir for bacterial colonisation. The aim of this study was to introduce the antibacterial effect of silver (Ag) to the biomineralised HA by utilising a polydopamine film as an intermediate layer for Ag and HA immobilisation. Sufficient catechol groups in polydopamine were required to bind chemically stainless steel 316L, Ag and HA elements. Different amounts of Ag nanoparticles were metallised on the polydopamine grafted stainless steel by varying the immersion time in silver nitrate solution from 12 to 24h. Another polydopamine layer was then formed on the metallised film, followed by surface biomineralisation in 1.5 Simulated Body Fluid (SBF) solution for 3days. Several characterisation techniques including X-Ray Photoelectron Spectroscopy, Atomic Force Microscopy, Scanning Electron Microscopy and Contact Angle showed that Ag nanoparticles and HA agglomerations were successfully immobilised on the polydopamine film through an element reduction process. The Ag metallisation at 24h has killed the viable bacteria with 97.88% of bactericidal ratio. The Ag was ionised up to 7days which is crucial to prevent bacterial infection during the first stage of implant restoration. The aged functionalised films were considered stable due to less alteration of its chemical composition, surface roughness and wettability properties. The ability of the functionalised film to coat complex and micro scale metal make it suitable for dental and orthopaedic implants application.

Plasma-assisted synthesis of Ag/ZnO nanocomposites: First example of photo-induced H 2 production and sensing

Ag/ZnO nanocomposites were developed by a plasma-assisted approach. The adopted strategy exploits the advantages of Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) for the growth of columnar ZnO arrays on Si(100) and Al 2O 3 substrates, in synergy with the infiltration power of the Radio Frequency (RF)-sputtering technique for the subsequent dispersion of different amounts of Ag nanoparticles (NPs). The resulting composites, both as-prepared and after annealing in air, were thoroughly characterized with particular attention on their morphological organization, structure and composition. For the first time, the above systems have been used as catalysts in the production of hydrogen by photo-reforming of alcoholic solutions, yielding a stable H 2 evolution even by the sole use of simulated solar radiation. In addition, Ag/ZnO nanocomposites presented an excellent response in the gas-phase detection of H 2, opening attractive perspectives for advanced technological applications.