As-prepared Ag Research Articles

Magnetic Silver Nanoparticles Stabilized by Superhydrophilic Polymer Brushes with Exceptional Kinetics and Catalysis.

Stimuli-responsive catalysts with exceptional kinetics and complete recoverability for efficient recyclability are essential in, for example, converting pollutants and hazardous organic compounds into less harmful chemicals. Here, we used a novel approach to stabilize silver nanoparticles (NPs) through magneto/hydro-responsive anionic polymer brushes that consist of poly (acrylic acid) (PAA) moieties at the amine functional groups of chitosan. Two types of responsive catalyst systems with variable silver loading (wt.%) of high and low (PAAgCHI/Fe3O4/Ag (H, L)) were prepared. The catalytic activity was evaluated by monitoring the reduction of organic dye compounds, 4-nitrophenol and methyl orange in the presence of NaBH4. The high dispersity and hydrophilic nature of the catalyst provided exceptional kinetics for dye reduction that surpassed previously reported nanocatalysts for organic dye reduction. Dynamic light scattering (DLS) measurements were carried out to study the colloidal stability of the nanocatalysts. The hybrid materials not only showed enhanced colloidal stability due to electrostatic repulsion among adjacent polymer brushes but also offered more rapid kinetics when compared with as-prepared Ag nanoparticles (AgNPs), which results from super-hydrophilicity and easy accumulation/diffusion of dye species within polymer brushes. Such remarkable kinetics, biodegradability, biocompatibility, low cost and facile magnetic recoverability of the Ag nanocatalysts reported here contribute to their ranking among the top catalyst systems reported in the literature. It was observed that the apparent catalytic rate constant for the reduction of methyl orange dye was enhanced, PAAgCHI/Fe3O4/Ag (H) ca. 35-fold and PAAgCHI/Fe3O4/Ag (L) ca. 23-fold, when compared against the as prepared AgNPs. Finally, the regeneration and recyclability of the nanocatalyst systems were studied over 15 consecutive cycles. It was demonstrated that the nanomaterials display excellent recyclability without a notable loss in catalytic activity.

Enhanced adsorption and degradation kinetics of methylene blue by Ag–Ag2S–CdS hybrid nanowires

In this paper, silver nanowires (Ag NWs) were initially synthesized by the polyol synthesis method. A simple hybridization of silver sulfide (Ag2S) and silver was achieved by simply mixing as-prepared Ag NWs with different concentrations of Na2S aqueous solution (0.01 and 0.001 M). To study the properties of the nanomaterials, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), Photoluminescence (PL) spectroscopy and UV–Visible (UV–Vis) spectroscopy were used. The ion exchange method was used to create Ag–Ag2S–CdS hybrid nanocatalysts. There has been no research further info on the degradation of methylene blue (MB) by an Ag– Ag2S–CdS nanocatalyst in the three environments (acid, neutral, alkaline). The MB dye was degraded for various minutes (min) in different pH degrees under the influence of sunlight using Ag–Ag2S–CdS. As a result of the experiments, the degradation efficiency of MB dye increased from 12.47 % to 57.02 % in the neutral, 40.58 %–80.08 % the in alkaline, and 91.87 %–97.92 % in the acid environment as time passed. The kinetics of the degradation process in each of the three settings was examined, and it was found that the neutral environment's photodegradation rate is a single value of 0.0029. This value varied depending on the time in a neutral and alkaline environment. As a result, the rate of degradation in the alkaline environment for the 60 min was 0.0071 (60–180 min), then 0.001 (120–300 min). The first degradation rate in an acidic environment was 0.0085 (60–120 min), then 0.0016 (120–300 min).

Synthesis of Silver Nanoparticles from Silver Closo-Dodecaborate Film for Enhanced Hydrogen Evolution.

The icosahedral closo dodecaborate cluster [B12H12]2- is gaining increasing interest due to its unique properties including the ease of functionalization, 3D aromaticity, and formation of metal salts with high ion conductivity. In this work, simple and effective preparation of silver closo dodecaborte (Ag2B12H12) films is reported by an electrochemical route. The size of the Ag2B12H12 particles in the films can be tuned from nanometers to micrometers by varying the electrochemical parameters. Ag nanoclusters with controllable sizes are successfully generated via electrochemical reduction reactions or thermal anneal of the Ag2B12H12 films. When tested for hydrogen evolution reaction (HER) in an acidic solution, the as-prepared Ag nanoparticles deliver a current density of 10mAcm-2 at 376mV overpotential. This research sheds light on a new synthesis of [B12H12]2- based thin films, the generation of metal nano-powders, and their application in HER or other applications.

Preparation of thiol-decorated Ag nanoparticles on N-doped carbon through resonant acoustic mixing for electrochemical CO2 reduction

The development of electrocatalysts with high selectivity and low overpotentials has been a prominent area of focus in electrochemical CO2 reduction (ECR) research. Supported metal nanoparticle (NP) has been received considerable interest due to the immense potential of remarkable activity, stability, and recyclability in ECR applications. However, the practical production of these supported metal NPs necessitates a facile and scalable approach. Addressing this challenge, the present study introduces a novel method for solid-state synthesis of Ag/C using resonant acoustic mixing (RAM). The RAM technique successfully facilitated the deposition of Ag nanoparticles onto n-doped carbon support, forming Ag/N-C catalysts. The as-prepared Ag electrocatalysts exhibited excellent dispersion and uniformity in terms of particle size. A thiol-decorated Ag electrocatalyst (Ag-Th/N-C) was prepared using a simple soaking method to establish an Ag-thiol interface enhancing catalytic activity caused by promoted electron transfer from Ag to CO2. Significantly, the Ag-Th/N-C catalyst demonstrated an improved Faradaic efficiency of 87.26% for the reduction of CO2 to CO at − 1.1 V versus RHE compared to the pristine Ag/C catalyst (55.45%).

One-Pot Biosynthesis of Carbon-Coated Silver Nanoparticles Using Palm Leaves as a Reductant and a Carbon Source.

In this study, carbon-coated silver nanoparticles (Ag@C NPs) were synthesized with a one-pot hydrothermal method using palm leaves as a reductant and a carbon source. SEM, TEM, XRD, Raman, and UV-vis analyses were employed to characterize the as-prepared Ag@C NPs. Results showed that the diameter of silver nanoparticles (Ag NPs) and the coating thickness could be controlled by changing the amount of biomass and the reaction temperature. The diameter ranged from 68.33 to 143.15 nm, while the coating thickness ranged from 1.74 to 4.70 nm. As the biomass amount and the reaction temperature increased, the diameter of Ag NPs and the coating thickness became larger. Thus, this work provided a green, simple, and feasible method for the preparation of metal nanocrystals.

TiO2 nanorods based self-supported electrode of 1T/2H MoS2 nanosheets decorated by Ag nano-particles for efficient hydrogen evolution reaction

Molybdenum disulfide (MoS2) has shown significant promise as an economic hydrogen evolution reaction (HER) catalyst for hydrogen generation, but its catalytic performance is still lower than noble metal-based catalysists. Herein, a silver nanoparticles (Ag NPs)-decorated 1T/2H phase layered MoS2 electrocatalyst grown on titanium dioxide nanorod arrays (Ag NPs/1T(2H) MoS2/TNRs) was prepared through acid-tunable ammonium ion intercalation. Taking advantage of MoS2 layered structure and crystal phase controllability, as-prepared Ag NPs/1T(2H) MoS2/TNRs exhibited ultrahigh HER activity. As-proposed strategy combines facile hydrogen desorption (Ag NPs) with efficient hydrogen adsorption (1T/2H MoS2) effectively circumventes the kinetic limitation of hydrogen desorption by 1T/2H MoS2. The as-prepared Ag NPs/1T(2H) MoS2/TNRs electrocatalyst exhibited excellent HER activity in 0.5 mol/L H2SO4 with low overpotential (118 mV vs. reversible hydrogen electrode (RHE)) and small Tafel slope (38.61 mV/dec). The overpotential exhibts no obvious attenuation after 10 h of constant current flow. First-principles calculation demonstrates that as-prepared 1T/2H MoS2 exhibit a large capacity to store protons. These protons can be subsequently transferred to Ag NPs, which significantly increases the hydrogen coverage on the surface of Ag NPs in HER process and thus change the rate-determining step of HER on Ag NPs from water dissociation to hydrogen recombination. This study provides a unique strategy to improve the catalytic activity and stability for MoS2-based electrocatalyst.

Elucidation of the capillarity-promoted sintering of silver nanoparticles produced by a spark ablation vapor source

Through the spark ablation method, high purity, spherical silver nanoparticles (Ag NPs) with a size of 5 ± 3 nm are prepared. A solvent-assisted sintering method is developed to modulate the sintering structure and properties of the as-prepared Ag NPs. The effects of the solvents terpineol, polyethylene glycol-200, 1,2-propanediol, and ethylene glycol are explored. The results show that treatment with ethylene glycol causes the shear strength of the sintered Ag NPs at 180, 220, 260, and 300 °C to significantly improve from 0, 3.7, 22.1, and 64.6 MPa to 37.1, 56.1, 76.6, and 93.1 MPa respectively. Additionally, the size and number of voids in the sintered structure are significantly reduced. From the perspective of the capillary pressure induced by the solvent during sintering, a correlation between low solvent wettability and small agglomerate size of the Ag NPs is revealed, which reasonably explains the structure and properties of the sintered Ag NPs that were treated with different solvents. The spark ablation and solvent-assisted sintering methods provide a new approach for the fabrication and structure–property design of metal NPs for electronic applications.

One-Step Exfoliation Method for Plasmonic Activation of Large-Area 2D Crystals.

Advanced exfoliation techniques are crucial for exploring the intrinsic properties and applications of 2D materials. Though the recently discovered Au-enhanced exfoliation technique provides an effective strategy for the preparation of large-scale 2D crystals, the high cost of gold hinders this method from being widely adopted in industrial applications. In addition, direct Au contact could significantly quench photoluminescence (PL) emission in 2D semiconductors. It is therefore crucial to find alternative metals that can replace gold to achieve efficient exfoliation of 2D materials. Here, the authors present a one-step Ag-assisted method that can efficiently exfoliate many large-area 2D monolayers, where the yield ratio is comparable to Au-enhanced exfoliation method. Differing from Au film, however, the surface roughness of as-prepared Ag films on SiO2 /Si substrate is much higher, which facilitates the generation of surface plasmons resulting from the nanostructures formed on the rough Ag surface. More interestingly, the strong coupling between 2D semiconductor crystals (e.g., MoS2 , MoSe2 ) and Ag film leads to a unique PL enhancement that has not been observed in other mechanical exfoliation techniques, which can be mainly attributed to enhanced light-matter interaction as a result of extended propagation of surface plasmonic polariton (SPP). This work provides a lower-cost and universal Ag-assisted exfoliation method, while at the same time offering enhanced SPP-matter interactions.

Constructing Ag modified NiCoSe2 hybrid nanosheet on 3D-nickel foam as a robust oxygen evolution reaction electrocatalyst

Transition metal selenides are promising oxygen evolution reaction (OER) catalysts, and element doping is a strategy to further enhance their catalytic performance. However, the choice of doping elements and methods needs further study. In this work for cobalt selenide, Ni is has been selected for isomorphic doping to NiCoSe2 with silver doped in bulk to obtain Ag–NiCoSe2 nanosheet on NF. The addition of nickel can form a eutectic phase with cobalt to obtain an effective synergistic catalytic effect. The addition of Ag can regulate the adsorption energy of the active site and conductivity. The as-prepared Ag–NiCoSe2/NF has good catalytic performance for OER, and a current density of 100 mA cm−2 can be achieved with only 270 mV. Its catalytic ability is far superior to that of non-Ag-doped NiCoSe2, which is due to the fact that the sheet structure provides more active sites, and the metal doping modulates the electronic configuration, which effectively improves the intrinsic activity. Moreover, Ag–NiCoSe2/NF can maintain a long-term high-efficiency catalytic process for more than 20 h at a current density of 100 mA cm−2. Therefore, this work proves that metal doping is of great significance for improving the catalytic activity of transition metal selenides.

Biosynthesis and antibacterial activity of silver nanoparticles using Flos Sophorae Immaturus extract

The current study proposes a green synthesis method for silver nanoparticles (Ag NPs) using various concentrations of Flos Sophorae Immaturus extract as reducing and capping agents. The UV-Visible (UV-Vis) spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) were used to characterize resulting brown nanopowder. The as-prepared Ag NPs had a high negative zeta potential value of ∼ -38 mv, indicating the existence of electrostatic stabilization. The average sizes of ∼27.8 nm, 28.5 nm, 34.3 nm and 36.5 nm were measured by TEM. Moreover, FTIR and XPS analyses validated the production and chemical composition of Ag NPs from silver nitrate. The antibacterial activity of Ag NPs was examined against E. coli, P. aeruginosa, and S. aureus using agar well diffusion and the minimum inhibitory concentration (MIC) method. The antibacterial activity of the as-prepared Ag NPs from 4 mL extract was excellent against E. coli, P. aeruginosa, and S. aureus and the MIC values were 31.250, 15.625, and 31.250 mg/L, respectively. Based on these results, this study proposes a practical approach for the synthesis of Ag NPs in the industry and medical fields.

In vitro toxicological assessment and biosensing potential of bioinspired chitosan nanoparticles, selenium nanoparticles, chitosan/selenium nanocomposites, silver nanoparticles and chitosan/silver nanocomposites

Hydrogen peroxide (H2O2) is widely used in various industries and biological fields. H2O2 rapidly contaminants with water resources and hence simple detection process is highly wanted in various fields. The present study was focused on the biosensing, antimicrobial and embryotoxicity of bioinspired chitosan nanoparticles (Cs NPs), selenium nanoparticles (Se NPs), chitosan/selenium nanocomposites (Cs/Se NCs), silver nanoparticles (Ag NPs) and chitosan/silver nanocomposites (Cs/Ag NCs) synthesized using the aqueous Cucurbita pepo Linn. leaves extract. The physico-chemical properties of as-synthesized nanomaterials were confirmed by various spectroscopic and microscopic techniques. Further, hydrogen peroxide (H2O2) sensing properties and their sensitivities were confirmed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) methods, in which Cs/Ag NCs showed pronounced sensing properties. In addition, the mode of antibacterial interaction results clearly demonstrated the effective inhibitory activity of as-prepared Ag NPs and Cs/Ag NCs against Gram negative pathogenic bacteria. The highest embryotoxicity was recorded at 0.19 μg/ml of Ag NPs and 1.56 μg/ml of Se NPs. Intriguingly, the embryo treated with Cs/Se NCs and Cs/Ag NCs significantly reduced the toxicity in the presence of Cs matrix. However, Cs/Se NCs did not show good response in H2O2 sensing than the Cs/Ag NCs, implying the biocompatibility of Cs/Ag NCs. Overall, the obtained results clearly suggest that Cs/Ag NCs could be suitable for dual applications such as for the detection of environmental pollutant biosensors and for biomedical research.

Wood-based multi-layered porous imprinted membranes with dual-metal composite nanostructures: Synergistic promotion of rebinding capacity, selectivity and permeability

Herein the Ag&TiO2-based propranolol-imprinted layers had been prepared onto basswood membrane surface based on a polydopamine (PDA)-induced self-polymerization/composite strategy. The as-prepared PDA-induced Ag&TiO2-based molecularly imprinted nanocomposite membranes (PAT-MIMs) showed superb specific recognition capability and permselectivity toward the template molecule of propranolol. Thereinto, the natural curved channel of basswood could efficiently promote the diffusion process of propranolol and improve the contact efficiency with surface recognition sites. Describing the entire synthetic strategy, the as-prepared PDA-induced Ag&TiO2-modified basswood-based membrane structure had been regarded as a threefold sol-gel imprinted-initiated system, thus constructing the propranolol-imprinted sites with key properties of high selectivity and rapid specific-recognizability. Therefore, enhanced adsorption performance of 118.6 mg/g, fast adsorption rate (within 30 min) and high permselectivity rates (more than 3.0) had been successfully harvested, which clearly illustrated the successful preparation of high-intensitive recognizability and permeability toward propranolol from complex separation system.

Low-temperature-fabrication and the preferred growth mechanism of Ag nanowires for stabling SnO2 film

A low-temperature-fabrication of Ag nanowires (NWs) was introduced for cost cutting and safety. Nucleating at room temperature (RT) for about 6 h and growing at 50–70 ℃ favored the formation of Ag NWs with the aspect ratio of more than 1000. The preferred growth mechanism of Ag NWs was the stacking of (220) or (2 2¯ 0) planes, which were the twinning planes of high-density twin crystals. Coating the as-prepared Ag NWs on the surface of SnO2 transparent semiconductor film and heat treating the bilayer film at 200–300 °C, the adhesion property and conductive performance of SnO2 film were significantly enhanced.

Effect of ultra-trace Ag doping on the antibacterial performance of carbon quantum dots

Ag,N co‐doping carbon quantum dots (Ag,N‐CQDs) were synthesized by applying a facile hydrothermal method with green and cheap precursors of ultra‐trace silver nitrate, citric acid, and ammonia solution. The as-prepared Ag,N‐CQDs deliver effective antimicrobial performance against Gram‐negative bacteria of Escherichia coli (E. coli) and Gram‐positive bacteria of Staphylococcus aureus (S. aureus). The microstructure of the Ag,N‐CQDs was analyzed by applying TEM, AFM, Raman spectra, and XPS spectra. Observations show that the Ag,N‐CQDs have a good crystallization structure with sizes of 5–9 nm and are assembled into nanoclusters with sizes of 10–80 nm. Antibacterial activities were determined on the basis of the colonies of E. coli and S. aureus, and the morphologies of the bacteria were observed by scanning electron microscopy. Spread plate tests show that the inhibition effect is sequenced as follows: Ag,N‐CQDs > Ag-CQDs > N‐CQDs > Ag solution. Thus, the doping of Ag in N-CQDs is a more effective way to enhance the antibacterial performance than the N-CQD and Ag solution. Furthermore, Ag,N‐CQDs display significant antibacterial activities against both bacteria colonies, while the N‐CQDs counterpart presents inhibitory effect against E. coli only. The lowest prevention concentrations of Ag,N‐CQDs are 250 and 200 μg mL−1 toward E. coli and S. aureus, respectively. The enhanced antibacterial performances of the Ag,N‐CQDs nanoclusters, especially to the S. aureus, are discussed and can be attributed to the strong adsorption of the polar chemical groups and the perforation effect of Ag atoms to disrupt bacterial membranes.

Ultrasound assisted synthesis of silver titanate for the differential pulse voltammetric determination of antibiotic drug metronidazole

Highly electroactive transition metal oxides have been received great potential in antibiotic drug electrochemical sensors due to excellent features including ease of preparation, a large number of active sites, good conductivity , high stability, and selectivity . In this work, the perovskite-type silver titanate (Ag 2 TiO 3 ) was synthesized by ultrasound-assisted coprecipitation method. The structural and morphology were examined using typical analytical techniques such as X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FT-IR), Raman spectrometry , field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) analyzes confirmed the purity and the chemical composition of as-prepared Ag 2 TiO 3 . The Brunauer−Emmett−Teller analysis (BET) of as-synthesized Ag 2 TiO 3 displayed a specific surface area of 48.485 m 2 g −1 resulted in improved charge transfer resistance (R ct ) of 695 Ω. The cyclic voltammetry (CV) analysis revealed the superior electrochemical performance of Ag 2 TiO 3 than other electrodes towards metronidazole (MTZ) detection. Under optimized differential pulse voltammetric (DPV) studies, the modified electrode exhibits a wide linear range of 0.1–104.3 μM with the lowest detection limit of 0.011 μM and a sensitivity of 0.371 μA μM −1 cm −2 . Furthermore, the fabricated sensor displayed excellent cyclic stability, reproducibility, repeatability, and noticeable selectivity in potentially effective interfering compounds for the detection of MTZ. The constructed electrode delivered good sensitivity to MTZ in urine and tablet with acceptable recoveries. Schematic diagram of as-synthesized Ag 2 TiO 3 towards electrochemical sensing of MTZ. • Perovskite-type Ag 2 TiO 3 was prepared by a simple ultrasonication method. • The as-synthesized Ag 2 TiO 3 modified electrode was optimized for the loading catalyst, pH, scan rate, peak current, and peak potential at the electrochemical determination of MTZ. • The fabricated sensor shows an extensive linear response from 0.1 to 104.3 μM with a low detection limit of 0.011 μM. • MTZ was successfully applied in real samples with good sensitivity and appropriate results.

Green Synthesis of Fluorescent Ag Nanoclusters for Detecting Cu2+ Ions and Its “Switch-On” Sensing Application for GSH

Herein, we prepared the L-histidine- (His-) protected silver nanoclusters (Ag NCs) by the microwave synthesis method. The synthesis process was rapid, facile, and environmentally friendly. Under 356 nm excitation, the as-prepared Ag NCs exhibited the blue fluorescence, and the fluorescence emission peak was located at 440 nm. The Ag NCs could successfully detect trace copper (Cu2+) ions in the aqueous solution and the limit of detection (LOD) was as low as 0.6 pM. Interestingly, the Ag NCs showed a different pH-dependent selectivity for both Cu2+ and iron (Fe3+) ions with no responses to other heavy metal ions. Furthermore, the as-fabricated fluorescent sensing system was utilized to detect glutathione (GSH, the LOD was 0.8 nM) by using the “switch-on” fluorescence recovery of Ag NCs through adding glutathione (GSH) to the Cu2+-Ag NCs solution.

Generation of Nanodroplet Reactors and Their Applications in In Situ Controllable Synthesis and Transportation of Ag Nanoparticles.

Nanodroplets have been paid great attention as they are crucial for a wide range of physical, chemical, and biological applications. In this paper, monodispersed nanodroplets are prepared and their directed motions are realized through conducting the formation of nonuniform structures via altering the ionic distribution within; all these dynamics have been observed by using in situ transmission electron microscopy liquid cell technology. It has been found that their transformation from random motion to directed motion is reversible. Moreover, combining multiple directed motions enables long‐distance travel with directed motion taking up 95% of the total time. The results here also prove that aqueous nanodroplets can slide directionally on the hydrophilic surface like droplets sliding on hydrophobic surface. Furthermore, the authors successfully achieve the unidirectional transportation of in situ prepared Ag nanoparticles by using the nanodroplets as nanoreactor, carrier, and transporter. The size and number of as‐prepared Ag nanoparticles can be quantitatively controlled. In summary, this research provides a new strategy for real‐time generation and precise manipulation of aqueous nanodroplets. Together with the quantitatively controllable in situ synthesis of Ag nanoparticles within the nanodroplets, this work can prove their promising applications in many fields.

Phytogenic Fabrication of Ag-Fe Bimetallic Nanoparticles for Cell Cycle Arrest and Apoptosis Signaling Pathways in Candida auris by Generating Oxidative Stress.

Novel green synthetic nanomedicines have been recognized as alternative therapies with the potential to be antifungal agents. Apoptosis induction, cell cycle arrest and activation of the antioxidant defense system in fungal cells have also gained attention as emerging drug targets. In this study, a facile and biodegradable synthetic route was developed to prepare Ag–Fe bimetallic nanoparticles using aqueous extract of Beta vulgaris L. Surface plasmon resonance of Beta vulgaris-assisted AgNPs nanoparticles was not observed in the UV-visible region of Ag–Fe bimetallic NPs, which confirms the formation of Ag–Fe nanoparticles. Beta vulgaris-assisted Ag–Fe NPs were characterized by FTIR spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and TGA-DTG analysis for their structural and morphological properties. The as-prepared Ag–Fe NPs were well dispersed and spherical with the average particle size of 15 nm. The antifungal activity of these Ag–Fe NPs against clinical isolates of Candida auris was determined by broth microdilution and cell viability assays. For insights into mechanisms, induction of apoptosis and triggering cell cycle arrest were studied following standard protocols. Furthermore, analysis of antioxidant defense enzymes was determined spectrophotometrically. Antifungal susceptibility results revealed high antifungal activity with MIC values ranging from 0.19 to 0.39 µg/mL. Further studies showed that Ag–Fe NPs were able to induce apoptosis, cell cycle arrest in G2/M phase and disturbances in primary and secondary antioxidant enzymes. This study presents the potential of Ag–Fe NPs to inhibit and potentially eradicate C. auris by inducing apoptosis, cell cycle arrest and increased levels of oxidative stress.

Synthesis and Characterization of Silver Nanoparticles with Ultrasound-Assisted Reverse Micelles Method and Their Antibacterial Effects on Methicillin-Resistant Staphylococcus aureus Isolates

Background: Serious infections are associated with methicillin-resistant Staphylococcus aureus (MRSA) bacteria and this can lead to many deaths in the world. The aim of the present study was to evaluate the antibacterial effect of silver nanoparticles (AgNPs) against MRSA isolates from clinical samples. Methods: Ag nanoparticles were synthesized by ultrasound-assisted reverse micelles method. The as-prepared Ag nanoparticles were characterized by X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The antibacterial effect of AgNPs was investigated using agar well diffusion assay and minimum inhibitory concentration (MIC) was determined. Results: The XRD studies showed that pure Ag nanoparticles have been produced after calcination. Synthesized AgNPs showed favorable effects on the bacteria used. MIC and minimum bactericidal concentration (MBC) values were determined to be 0.015 and 0.07 mg/mL, respectively. All MRSA isolates were susceptible to AgNPs. In contrast, they showed high resistance to multiple classes of antibiotics. Conclusions: AgNPs had high inhibitory activity against MRSA; therefore, they can be proposed as an alternative or adjuvant to antibiotics for the treatment of MRSA infections. Further investigations are required to assess the safety and efficacy of AgNPs in the body.

Ecofriendly Synthesis of Silver Nanoparticles Using Aqueous Extracts of Zingiber officinale (Ginger) and Nigella sativa L. Seeds (Black Cumin) and Comparison of Their Antibacterial Potential

Applications of chemical synthetic methods for the preparation of metal nanoparticles involve toxic reagents, which are hazardous to both humans and the environment. On the other hand, ecofriendly plant-based techniques offer rapid, non-toxic, and suitable alternatives to the traditional methods. Herein, we report an eco-friendly method for the preparation of silver nanoparticles (Ag NPs) using two different aqueous extracts of Zingiber officinale (ginger) and Nigella sativa L. seeds (black cumin). Successful preparation of Ag NPs was confirmed by X-ray diffraction, ultraviolet–visible (UV-Vis) spectroscopy, and energy dispersive spectroscopy (EDX). Transmission electron microscopy (TEM) analysis revealed that Nigella sativa L. seed extract (NSE) produced a smaller size of NPs (~8 nm), whereas the ginger extract (GE) led to the formation of slightly larger Ag NPs (~12 nm). In addition, to study the effect of concentration of the extract on the quality of resulting NPs, two different samples were prepared from each extract by increasing the concentrations of the extracts while using a fixed amount of precursor (AgNO3). In both cases, a high concentration of extract delivered less agglomerated and smaller-sized Ag NPs. Furthermore, the antibacterial properties of as-prepared Ag NPs were tested against different bacterial strains. Notably, despite the slightly better quality of Ag NPs obtained from NSE (NSE-Ag), NPs prepared by using GE (GE-Ag) demonstrated superior antibacterial properties. In case of the plant-extract-based synthesis of nanoparticles, it is widely reported that during the preparation, the residual phytomolecules remain on the surface of resulting NPs as stabilizing agents. Therefore, in this case, the high antibacterial properties of GE-Ag can be attributed to the contributing or synergetic effect of residual phytomolecules of GE extract on the surface of Ag NPs, since the aqueous extract of GE has been known to possess higher intrinsic bactericidal properties when compared to the aqueous NSE extract.