Mixture Of Silver Nanoparticles Research Articles

Separate and Simultaneous Effects of Silver Nanoparticles and Arsenic on the Taxonomic Diversity of Free-Living Marine Nematodes

The effects of silver nanoparticles and arsenic at community levels have rarely been assessed in laboratory experiments, despite their obvious advantage in reflecting better the natural conditions compared to traditionally single species-focused toxicological experiments. In the current study, the multifaceted effects of these xenobiotics, acting alone or combined, on meiobenthic nematodes were tested in a laboratory experiment carried out in microcosms. The nematofauna was exposed to two concentrations (0.1 and 1 mg·L−1) of silver nanoparticles (Ag1/Ag2) and arsenic (As1/As2), as well as to a mixture of both compounds, for 30 days. The results particularly highlighted a significant decrease in the abundance and taxonomic diversity of nematodes directly with increasing dosages of these compounds when added alone at the highest concentration. The addition of these levels of xenobiotics seems to make the sediment matrix gluey, hence inducing greater mortality among microvores and diatoms feeders. Moreover, the nematofauna went through a strong restructuring phase following the exposure to both compounds when added alone, leading to the disappearance of sensitive taxa and their replacement with more tolerant ones. However, the similarity in nematofauna composition between control and mixtures of silver nanoparticles and arsenic (except for Ag1As2) suggests that the toxicity of the latter pollutant could be attenuated by its physical bonding to the former.

Rapid Communication: oxidative stress induced by mixed exposure to glyphosate and silver nanoparticles

ABSTRACT The aim of this study was to examine oxidative stress induced by the binary mixture of silver nanoparticles (AgNP) and glyphosate (Gly) in Daphnia magna by measurement of reactive oxygen species (ROS) production, glutathione (GSH) levels, enzyme activities of catalase (CAT) and superoxide dismutase (SOD) as well as malondialdehyde (MDA) content. Acute exposure of Daphnia magna to binary mixture of AgNP and Gly resulted in significant biochemical responses indicative of oxidative damage. This response seemed to be related to imbalance in enzymatic/non-enzymatic antioxidant enzymes associated with intracellular overproduction of ROS and significant increase in MDA levels, indicating that the integrity and function of the cell membrane was damaged. These changes adversely affected the fitness and survival of Daphnia magna and negatively influenced offspring growth and reproduction.

The Effects of Oral Silver Nanoparticles and Propolis on the Level of Lipid Peroxidation in Male Wistar Rats

Background: Oxidative stress is a leading factor in developing silver nanoparticle-induced toxicity. Objective: This study evaluated the effects of oral prescription of different doses of silver nanoparticles and propolis on lipid peroxidation in male Wistar rats. Methods: The male Wistar rats were randomly divided into four groups. Control group and three different treatment groups with oral prescription of 30 ppm, 60 ppm, and 60 ppm of silver nanoparticles with 200 mg/kg of propolis. The serum level of Malondialdehyde (MDA) was measured by Thiobarbituric Acid Reactive Substances (TBARS) assay using Thiobarbituric Acid (TBA). Results: The serum level of MDA as a marker of lipid peroxidation in the control group was 1.92 mM/mL, and in other groups that received silver nanoparticles (30 ppm, 60 ppm, 60 ppm with 200 mg/kg propolis) were respectively 2.82, 3.83 and 2.62 mM/mL. MDA level also increased at the doses of 30 ppm and 60 ppm compared to the control group and decreased when propolis was prescribed with silver nanoparticles in the third group; however, its value did not reach the level of the control group. Minimal levels of serum lipid peroxidation were observed when silver and propolis nanoparticles were administered to male rats. Conclusion: The mixture of silver nanoparticles and propolis reduces the toxic effects of silver nanoparticles; it preserves and increases the efficiency of this compound in medical applications.

Removal of Cadmium and Chromium by Mixture of Silver Nanoparticles and Nano-Fibrillated Cellulose Isolated from Waste Peels of Citrus Sinensis.

Nano-fibrillated cellulose (NFC) was extracted by a chemical method involving alkali and acid hydrolysis. The characterisation of the citrus sinensis fruit peel bran and nano-fibrillated cellulose was performed by XRD, FTIR, TEM, and FESEM. XRD confirmed the phase of NFC which showed monoclinic crystal with spherical to rod shape morphology with a size of 44–50 nm. The crystallinity index of treated NFC increased from 39% to 75%. FTIR showed the removal of lignin and hemicellulose from waste peels due to the alkaline treatment. Silver nanoparticles were also synthesised by utilizing extract of citrus sinensis skins as a reducing agent. Pharmaceutical effluent samples from an industrial area were tested by Atomic Absorption Spectrometry. Out of the four metals obtained, cadmium and chromium were remediated by silver nanoparticles with nano-fibrillated cellulose via simulated method in 100 mg/L metal-salt concentrations over a time period of 160 min. The highest removal efficiency was found for cadmium, i.e., 83%, by using silver and NFC together as adsorbents. The second highest was for chromium, i.e., 47%, but by using only NFC. The Langmuir and Freundlich isotherms were well fitted for the sorption of Cd (II) and Cr (II) with suitable high R2 values during kinetic simulation. Thus, the isolation of NFC and synthesis of silver nanoparticles proved efficient for heavy metal sorption by the reuse of waste skins.

Improved antimicrobial properties of methylene blue attached to silver nanoparticles.

Photosensitizing agents are the cornerstone of Photodynamic Therapy (PDT). They play an essential role in deactivation process of multidrug resistant pathogens and tumor treatments. In this work, we studied a photosensitizing agent made from mixture of Silver Nanoparticles (Ag NPs) and Methylene Blue (MB) which possess improved important characteristics like high photostability and high singlet oxygen yield. Ag NPs were synthesized by pulsed laser ablation technique in different aqueous solutions like polyvinylpyrrolidone (PVP), citrate and Deionized (DI) water. The synthesized AgNPs were characterized in depth using with transmission electron microscopy (TEM), UV-vis (UV-vis), and photoluminescence (PL) spectra. These Ag NPs were combined with MB and used to eradicate the Gram-negative bacteria, Escherichia coli (E. coli), and Gram-positive bacteria, Staphylococcus aureus (S. aureus). MB and Ag NPs mixture was found to possess higher antimicrobial activity and thus were more effective in killing both Gram -positive and Gram-negative bacteria in comparison to individual exposure of MB and Ag NPs. Additionally, the antimicrobial effects varied with respect to the size of nanoparticles as well as the medium used for their synthesis. The data from this study supports the potential use of the proposed method in PDT where standard photosensitizers have limitations.

Biofabrication of AgNPs Nanoparticles and Their Loading with Sevoflurane, a Volatile Anesthetic Drug for Therapeutic Treatment of Focal Cerebral Ischemia-In-Vivo Studies in Rats

The process of green reduction was used to prepare the colloidal mixture of silver nanoparticles (AgNPs) with the help of silver nitrate (AgNO3), which is used as a precursor along with the existence of Bischofia javanica leaf extract that plays both as a reducing as well as capping agent. An aesthetic drug which is volatile in nature and is used to form nano-drug complex (SF-AgNPs), Sevoflurane (SF) was used to functionalize the fabricated AgNPs. The interaction and loading of the drug with AgNPs is studied with the help of several analytical mechanisms such as dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet–visible (UV–Vis) absorption spectra. Several reflections in the XRD spectra and the shift observed in the SPR peak of UV–Vis is accredited to the loading of SF on the surface of AgNPs. When related with the bare NPs, the growth in the size of SF-loaded NPs confirms the loading of drug. Further investigation disclosed that the SF-AgNPs of 20 nm increased the fabrication of anti-inflammatory cytokines, along with the inhibition of ischemia–reperfusion induced microglias and astrocytes activation. In addition, the molecules of pro-apoptotic were down regulated and the expressions of anti-apoptotic proteins were up regulated in the post-ischemic brains. When examining the group treated with 15 nm AgNPs, these effects were noticed to be conflicting. These responses exposed that the neuroprotection of SF-AgNPs 20 nm was ascribable to its anti-apoptotic as well as anti-inflammatory effects. The present work can deliver a unique approach for the healing of cerebral ischemia–reperfusion injury. Owing to the above results, this work provided modernized understandings into the self-treatment of SF-AgNPs for cerebral ischemic stroke (IS).

Low temperature synthesis and SERS application of silver molybdenum oxides

AgxMoyOz (Ag/α-MoO3, Ag/h-MoO3, Ag/β-MoO3, Ag2Mo2O7, and Ag2MoO4) nanomaterials are synthesized at relatively low temperature (80 °C) and with a short hydrothermal treatment time (3 h) using glucose (Glc) as a catalyst. Contrary to previous studies, it is possible to synthesize one of the AgxMoyOz binaries at 80 °C by altering the pH of the reaction media in the presence of glucose. In addition, further experiments indicate that Ag/h-MoO3, Ag2Mo2O7 and Ag/β-MoO3 can be converted to Ag/α-MoO3 which can also be synthesized from a reaction involving ammonium heptamolybdate tetrahydrate and AgNO3 at room temperature using cysteamine in both methods. Characterization with UV-Vis, XRD and Raman spectroscopy reveals high purity of as-synthesized product. These synthesized products are finally used to fabricate SERS substrates by coating a silicon wafer with a mixture of silver nanoparticles (Ag NPs) and AgxMoyOz (Si@Ag/AgxMoyOz). The results show a good sensitivity and stability. In addition, it is also found that the SERS activity of Si@Ag/AgxMoyOz is higher than that of Si@Ag.

Large-scale synthesis of silver nanowires via a solvothermal method

Silver nanostructures have been synthesized through a simple solvothermal method by reducing silver nitrate (AgNO3) with ethylene glycol (EG) and using poly(vinylpyrrolidone) (PVP) as an adsorption agent. Different concentrations of ferric chloride (FeCl3) are added into the solution. It is found that AgCl colloids formed in the initial stage greatly influence the final morphologies of the products. When a low-concentration FeCl3 solution is used, there is a mixture of silver nanoparticles and nanowires. However, when a high-concentration FeCl3 solution (100 μM) is used, large amounts of AgCl colloids appear, resulting in decreasing free Ag+ during initial formation of silver seeds and slowly releasing of Ag+ to the solution in the subsequent reaction. This leads to the formation of silver nanowires. Furthermore, an increase in the concentration of FeCl3 from 100 to 300 μM results in the synthesis of silver nanowires with larger sizes. In addition, Fe(III) is reduced to Fe(II) form which in turn reacts with and removes adsorbed atomic oxygen from the surface of silver seeds. In this case, uniform silver nanowires can be obtained.

Separation and Quantitation of Silver Nanoparticles using Sedimentation Field‐Flow Fractionation

Sedimentation field‐flow fractionation (SdFFF) provides a mass based separation, and, thus, a size based separation for particles of uniform density. In this study, SdFFF was employed for separation and determination of size distributions of silver nanoparticles of about 100 nm in diameter. The relative abundances of each population in binary mixtures of silver nanoparticles were determined by mathematically deconvoluting the SdFFF fractograms. Various experimental parameters, including the field strength (channel rotation rate), flow rate, and the carrier composition, were varied to find an optimum SdFFF condition for separation and analysis of silver nanoparticles. The field and/or flow programming were also tested to improve the resolution. The silver nanoparticles were not resolved well when pure water was used as the carrier, due to charge interactions among the particles and between the particles and the channel wall. Water with 0.1% FL‐70 was chosen as the dispersing medium and also as the carrier for SdFFF analysis of silver nanoparticles.

Rapid bioparticle concentration and detection by combining a discharge driven vortex with surface enhanced Raman scattering.

Rapid concentration and detection of bacteria in integrated chips and microfluidic devices is needed for the advancement of lab-on-a-chip devices because current detection methods require high concentrations of bacteria which render them impractical. We present a new chip-scale rapid bacteria concentration technique combined with surface-enhanced Raman scattering (SERS) to enhance the detection of low bacteria count samples. This concentration technique relies on convection by a long-range converging vortex to concentrate the bacteria into a packed mound of 200 mum in diameter within 15 min. Concentration of bioparticle samples as low as 10(4) colony forming units (CFU)ml are presented using batch volumes as large as 150 mul. Mixtures of silver nanoparticles with Saccharomyces cerevisiae, Escherichia coli F-amp, and Bacillus subtilis produce distinct and noticeably different Raman spectra, illustrating that this technique can be used as a detection and identification tool.