Activity Of Green Synthesized Silver Nanoparticles Research Articles

In vitro and in vivo comparative analysis of antibacterial activity of green-synthesized silver nanoparticles.

This study aims to compare antibacterial effects of green-synthesized silver nanoparticles (AgNPs) with silver nitrate (AgNO3 ). AgNPs were successfully synthesized using Eucalyptus camaldulensis leaf extract as a reducing and stabilizing agent. Minimum inhibitory concentrations (MIC) of AgNPs and AgNO3 against Staphylococcus aureus and Pseudomonas aeruginosa ranged between 4.8-6.75μg/mL. Growth curves demonstrated that inhibition of P. aeruginosa occurred right after AgNPs were added and throughout the period of the study (72h). Antibacterial effects of both AgNPs and AgNO3 could be abrogated by cysteine and 2-mercaptoethanol, thiol-containing compounds. Galleria mellonella model revealed relatively low toxic effects of both AgNPs and AgNO3 . At 20MIC of AgNPs (≈137.8mg/kg), more than 80% survival of G. mellonella was observed. Unexpectedly, silver-containing agents could not rescue larvae after S. aureus infection. Further ex vivo experiments in the presence of coelomic larval fluid demonstrated the reduction of antibacterial activity of both AgNPs and AgNO3 . We speculated that anionic molecules present in the coelomic fluid might neutralize the action of Ag ions. Binding of AgNPs or AgNO3 to albumin, a major protein in human blood which transport several endogenous compounds was not detected, indicating that the silver-containing agents could be applied as an antimicrobial agent. This article is protected by copyright. All rights reserved.

Antibacterial and anticancer activities of green-synthesized silver nanoparticles using Photinia glabra fruit extract.

Aims: We prepared Photinia glabra (PG) aqueous fruit extract, utilized it to synthesize silver nanoparticles (PG-Ag NPs) and evaluated theantibacterial and anticancer activities of the nanoparticles (NPs). Materials & methods: Silver nitrate aqueous solution was reduced to PG-Ag NPs usingaqueous PGfruit extract. NP shape, size, composition and functionalization were determined using transmission electron microscopy, x-ray photoelectron spectroscopy, Fourier transform infraredand x-ray diffraction. Results & conclusions: PG-Ag NPs were spherical, approximately39-77 nm-sized, functionalized surfaces with notable antibacterial activity against both Escherichia coli and Staphylococcus aureus, with anMIC <30ug/ml and cytotoxicity toward esophageal cancer cells, with IC50 values less than20ug/ml. PG-Ag@rt NPs have been shown to bea potent antibacterial and anticancer agent, and their enriched particle surfaces can be conjugated with other compounds for multibiomedical applications.

Antibacterial and Antifungal Activity of Green-synthesized Silver Nanoparticles Using Spinacia oleracea leaves Extract

In this study, silver nanoparticles (AgNPs) were green synthesized using aqueous leaf extracts of green spinach that have been used as antimicrobial agents. The antimicrobial efficacy was evaluated against bacterial and fungal strains. The morphological structures, optical and surface properties of as-synthesized nanoparticles have been investigated via a Transmission electron microscope, X-ray diffraction, UV-Vis absorption, and Fourier transform infrared, respectively. The colloidal stability was evaluated using dynamic light scattering and zeta-potential measurements. The average size of as-synthesized particles was about 15±5nm. The green synthesized AgNPs showed significant antibacterial activity against different bacterial species via the agar well diffusion assay. The inhibition zones were varied from 27 to 34mm against 6 bacterial species (K. pneumoniae, E.coli, A. baumannii, P. aeruginosa, S. aureus, and S. haemolyticus). In such a case, the minimal inhibition concertation of AgNPs against bacterial isolates was 4μg/ml for all isolates, except E.coli was 8μg/ml. Also, the silver particles showed an antifungal behavior against 4 fungal species (A. niger, P. marneffie, C. glabrata and C. parapsilosis) with an inhibition zone from 19 to 39mm in diameter. Whereas, the MICs for fungal isolates 8μg/ml for all isolates. Treated Wi-38 cells with AgNPs demonstrated various levels of cytotoxicity dependent on the concentration of AgNPs using MTT assay with IC50  447.6. Moreover, the current study presents a facile and cost-effective synthesis of AgNPs via green chemical methods to be used as antimicrobial agents. Further in-vivo assessment is required to evaluate their therapeutic efficacy against MDR microorganisms.

Antibacterial Activity of Green-Synthesized Silver Nanoparticles Using Areca catechu Extract against Antibiotic-Resistant Bacteria.

In this work, the antibacterial activity of silver nanoparticles (AgNPs) synthesized using Areca catechu extracts against three species of antibiotic-susceptible and three species of resistant bacteria was investigated. The effects of this plant were more promising when compared with other medicinal plants tested. The hydrothermal extract of Areca catechu was mixed with silver nitrate to synthesize AgNPs. The synthesized particle characteristics were analyzed by UV–Vis spectrophotometry, scanning electron microscopy (SEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FT-IR). Minimum inhibitory concentration and minimum bactericidal concentration tests were conducted to confirm antibacterial activity and the results showed that AgNPs synthesized using Areca catechu extracts effectively inhibited the growth of bacterial species. Moreover, the SEM images of the bacterial species treated with AgNPs synthesized with Areca catechu extracts showed that clusters of AgNPs were attached to the surface of the bacterial cell wall, which could induce destruction of the cell membranes. The results suggest that AgNPs synthesized with Areca catechu extracts have the potential to treat antibiotic-resistant bacteria known as the major cause of nosocomial infections.

In vitro bactericidal, antidiabetic, cytotoxic, anticoagulant, and hemolytic effect of green-synthesized silver nanoparticles using Allium sativum clove extract incubated at various temperatures

AbstractThe current research aimed to evaluatein vitrobiological activities of green-synthesized silver nanoparticles using theAllium sativumclove extract. The stability of green-synthesized silver nanoparticles was evaluated via storage at 4°C, room temperature (37°C), and calcined at 300°C, 500°C, and 700°C. The antibacterial effect was evaluated using agar well, spread plate, biofilm reduction, and cell proliferation inhibition assays. The cytotoxic and antidiabetic effects were determined via brine shrimp lethality, protein kinase inhibition, and α-amylase inhibition assays. DPPH scavenging, iron-chelating, anticoagulant, and hemolytic effects were evaluated. The highest inhibition ofKlebsiella pneumoniaewas observed when freshly prepared, calcined (300°C), and stored nanoparticles (4°C and 37°C) were applied (9.66, 9.55, 7.33, and 6.65 mm) against freshly prepared and calcined at 700°C which showed the highest inhibition ofPseudomonas aeruginosa(8.55 and 7.66 mm). Cell viability assay, biofilm reduction assay, and spread plate method showed a significant antibacterial effect of freshly prepared silver nanoparticles. Freshly prepared and calcined nanoparticles at 300°C and 500°C possessed strong antioxidant and iron-chelating activity. Among all the synthesized silver nanoparticles, freshly prepared and calcined nanoparticles (300°C and 500°C) increases the prothrombin time. Silver nanoparticles possessed significant anticoagulant properties and less toxic at least concentration toward human RBCs. In brine shrimp lethality assay, freshly prepared nanoparticles showed a stronger toxic effect and caused high mortality of larvae. Protein kinase inhibition assay revealed that freshly prepared nanoparticles had the highest zone of inhibition (18.0 mm) at 50 µg/disc. Green-synthesized nanoparticles would be used as potential therapeutic agents to overcome both infectious and noninfectious diseases.

Biological activity of green-synthesized silver nanoparticles depends on the applied natural extracts: a comprehensive study

Due to obvious disadvantages of the classical chemical methods, green synthesis of metallic nanoparticles has attracted tremendous attention in recent years. Numerous environmentally benign synthesis methods have been developed yielding nanoparticles via low-cost, eco-friendly, and simple approaches. In this study, our aim was to determine the suitability of coffee and green tea extracts in green synthesis of silver nanoparticles as well as to compare the performance of the obtained materials in different biological systems. We successfully produced silver nanoparticles (C-AgNP and GT-AgNP) using coffee and green tea extracts; moreover, based on our comprehensive screening, we delineated major differences in the biological activity of C-AgNPs and GT-AgNPs. Our results indicate that although GT-AgNPs exhibited excellent antimicrobial activity against all the examined microbial pathogens, these particles were also highly toxic to mammalian cells, which limits their potential applications. On the contrary, C-AgNPs manifested substantial inhibitory action on the tested microbes but were nontoxic to human and mouse cells, indicating an outstanding capacity to discriminate between potential pathogens and mammalian cells. These results clearly show that the various green materials used for stabilization and for reduction of metal ions have a defining role in determining and fine-tuning the biological activity of the obtained nanoparticles.

Catalytic and antibacterial activities of green-synthesized silver nanoparticles on electrospun polystyrene nanofiber membranes using tea polyphenols

An efficient and environmentally friendly method has been developed to prepare Ag nanoparticles (AgNPs) coated tea polyphenols/polystyrene (Ag-TP/PS) nanofiber membrane, which combines electrospinning and in situ reduction of [Ag(NH3)2]+ using TP as the reductant and stabilizer. In this method, TP/Pluronic/PS nanofiber membranes are fabricated by electrospinning and then immersed in the aqueous solution of [Ag(NH3)2]+. While TP is being released from TP/Pluronic/PS nanofibers, the surface of TP/Pluronic/PS nanofibers could function as reactive sites for reduction of [Ag(NH3)2]+ without any extra reagents. XRD results indicate that AgNPs thus formed are in metallic form of Ag0. SEM images show that AgNPs can be densely and uniformly coated on the surface of TP/Pluronic/PS nanofibers. The as-prepared Ag-TP/PS nanofiber membranes exhibit excellent catalytic properties for the degradation of methylene blue. Furthermore, the effect of [Ag(NH3)2]+ concentration on the morphology and catalytic activity of the membrane is investigated. In addition, the antibacterial assays reveal that Ag-TP/PS nanofiber membrane possesses extraordinary antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms. The free-standing membrane is flexible and easy to handle, which is promising for potential applications in catalysis, antibacterial agents and water remediation fields.

Mosquitocidal and antibacterial activity of green-synthesized silver nanoparticles from Aloe vera extracts: towards an effective tool against the malaria vector Anopheles stephensi?

Mosquitoes represent an important threat for lives of millions of people worldwide, acting as vectors for devastating pathogens, such as malaria, yellow fever, dengue, and West Nile. In addition, pathogens and parasites polluting water also constitute a severe plague for populations of developing countries. Here, we investigated the mosquitocidal and antibacterial properties of Aloe vera leaf extract and silver nanoparticles synthesized using A. vera extract. Mosquitocidal properties were assessed in laboratory against larvae (I-IV instar) and pupae of the malaria vector Anopheles stephensi. Green-synthesized silver nanoparticles were tested against An. stephensi also in field conditions. Antibacterial properties of nanoparticles were evaluated against Bacillus subtilis, Klebsiella pneumoniae, and Salmonella typhi using the agar disk diffusion and minimum inhibitory concentration protocol. The synthesized silver nanoparticles were characterized by UV-vis spectrum, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In laboratory conditions, the A. vera extract was toxic against An. stephensi larvae and pupae, even at low dosages. LC50 were 48.79 ppm (I instar), 59.09 ppm (II instar), 70.88 ppm (III instar), 83.58 ppm (IV instar), and 152.55 ppm (pupae). Green-synthesized silver nanoparticles were highly toxic against An. stephensi. LC50 were 3.825 ppm (I instar), 4.119 ppm (II instar), 4.982 ppm (III instar), 5.711 ppm (IV instar), and 6.113 ppm (pupae). In field conditions, the application of A. vera-synthesized silver nanoparticles (10 × LC50) leads to An. stephensi larval reduction of 74.5, 86.6, and 97.7%, after 24, 48, and 72 h, respectively. Nanoparticles also showed antibacterial properties, and the maximum concentration tested (150 mg/L) evoked an inhibition zone wider than 80 mm in all tested bacterium species. This study adds knowledge about the use of green synthesis of nanoparticles in medical entomology and parasitology, allowing us to propose A. vera-synthesized silver nanoparticles as effective candidates to develop newer and safer mosquitocidal control tools.