Synthesis Of Antimicrobial Silver Nanoparticles Research Articles

Green Synthesis of Antimicrobial Silver Nanoparticles using Green Tea Extract: The Role of Concentration and pH

ABSTRACTGreen synthesis for silver nanoparticles (AgNPs) is the process of reducing Ag+ ions to Ag0 by using plant bioactive compounds. Green synthesis is safer, environmentally friendly and cost-effective. Plant bioactive compounds from Camellia sinensis L. (green tea) extract containing polyphenols can be used as a reducer in the formation of silver nanoparticles. This study aims to determine the effect of pH (8, 9, and 10), at 1,5mM AgNO3 concentration and 0,75% green tea extract concentration on the physical characteristics and antibacterial activity of silver nanoparticles prepared by green synthesis method. The synthesized results were evaluated by UV-Vis Spectrophotometer, Dynamic Light Scattering (DLS), SEM, and FTIR. The optimal AgNP synthesis process resulted from the AgNO3 concentration of 1.5 mM with 0.75% green tea extract at pH 10 which showed an absorbance value of 4,420 at λ 435,3 nm, with a particle size of 47,1 nm and a PDI of 0,243. The formation of AgNPs was observed by a change in color to brownish yellow. Antibacterial activity of AgNPs using liquid diffusion method. The results obtained AgNPs for Staphylococcus aureus bacteria has had inhibition at a concentration of 0,187mM and Escherichia coli at a concentration of 0,375mM.Keywords: Silver nanoparticles; green synthesis; green tea extract; pH; antibacterial activity

Green synthesis of antimicrobial silver nanoparticles using fruit extract of Glycosmis pentaphylla and its theoretical explanations

The present study reports a novel, one-pot, cost-effective, green synthesis route of silver nanoparticles (AgNPs) from the fruit epicarp extract of Glycosmis pentaphylla (FGP). The UV–Vis spectroscopy (UV-Vis), dynamic light scattering (DLS), and transmission electron microscopy (TEM) studies confirmed that the synthesis produces stable, monodispersed AgNPs with an average size of 17 nm. Fourier transform infrared spectroscopy (FTIR) studies suggested that the carbonyl group of the different compounds of FGP made significant interaction with AgNPs. With this indication, a theoretical simulation using density functional theory (DFT) was performed, which established that among the different compounds of FGP, arborine was mainly responsible for the stabilization of AgNPs with a binding energy of 58.45 kJ/mol. Synthesized AgNPs showed strong antifungal (against Alternaria alternata, Colletotrichum lindemuthianum, Fusarium moniliforme, and Candida glabrata) and antibacterial (against Bacillus subtilis, Streptococcus mutans, Escherichia coli, and Salmonella enterica serovar Typhimurium) activity. Synthesized AgNPs showed the highest antifungal activity against Fusarium moniliforme and the highest antibacterial activity against Salmonella enterica serovar Typhimurium. A remarkable synergistic activity of AgNPs was observed with fungicide Bavistin (∼25% increased activity against Alternaria alternata) and antibiotic Streptomycin (∼33.3% increased activity against Bacillus subtilis), which indicated that AgNPs could be applied to control crop and human pathogens with a lower dose of synthetic antimicrobial compounds (e.g., Bavistin, Streptomycin, etc.). Hence, green synthesized AgNPs by this method can be a blessing for crop productivity and hospital management as an effective alternative to conventional fungicides and antibiotics, respectively.

Green synthesis of antimicrobial silver nanoparticles with Brassicaceae seeds

Herein, we demonstrate a facile and green route for the synthesis of silver nanoparticles (AgNPs) from silver nitrate and seed extracts of different vegetable seeds of Brassicaceae family. All the nanocomposites were fully characterized in the solid-state via various techniques such UV–vis spectrophotometer (UV–Vis); x-ray diffraction (XRD), High-resolution transmission electron microscopy (HR-TEM), energy-dispersive x-ray spectroscopy (EDS), and Fourier transform infrared (FTIR) spectrometry. The experimental parameters such as variation in seeds extract concentration, temperature, stirring time and pH were noted and optimum condition of concentration (20 ml), temperature (80 °C) and pH 8.5 was selected for the synthesis of NPs. Optical absorbance of AgNPs at ≈425 nm indicated the formation of metallic silver through surface plasmon resonance. The successful capping of biological macromolecules was confirmed by FTIR spectroscopy. XRD pattern depicted the formation of face-centered cubic silver nano-composite with average crystal size ranges from ≈14–20 nm. Bio-synthesized Ag nanoparticles showed enhanced antibacterial potential against gram-positive (B. safensis, B. subtilis, B. pumilis and S. aureus) and negative gram (E. coli and S.typhi) strains by disc diffusion method. Highest antimicrobial activity was given by sample S3 (17 mm) against B. pumilis whereas, sample S2 and S5 also showed significant bactericidal potential against B. pumilis that is 15 mm. While highest zone of inhibition for sample S1 and S4 is 14 mm.

Retraction: Analysis of antimicrobial silver nanoparticles synthesized by coastal strains of Escherichia coli and Aspergillus niger

The present study investigated the extracellular biosynthesis of antimicrobial silver nanoparticles by Escherichia coli AUCAS 112 and Aspergillus niger AUCAS 237 derived from coastal mangrove sediment of southeast India. Both microbial species were able to produce silver nanoparticles, as confirmed by X-ray diffraction spectrum. The nanoparticles synthesized were mostly spherical, ranging in size from 5 to 20 nm for E. coli and from 5 to 35 nm for A. niger, as evident by transmission electron microscopy. Fourier transform spectroscopy revealed prominent peaks corresponding to amides I and II, indicating the presence of a protein for stabilizing the nanoparticles. Electrophoretic analysis revealed the presence of a prominent protein band with a molecular mass of 45 kDa for E. coli and 70 kDa for A. niger. The silver nanoparticles inhibited certain clinical pathogens, with antibacterial activity being more distinct than antifungal activity. The antimicrobial activity of E. coli was more pronounced than that of A. niger and was enhanced with the addition of polyvinyl alcohol as a stabilizing agent. This work highlighted the possibility of using microbes of coastal origin for synthesis of antimicrobial silver nanoparticles.

Antimicrobial Applications of Silver Nanoparticles to E. coli Colony Biofilms.

Bacterial biofilms can cause problems in various arenas, from the fouling of water processing equipment to persistent in vivo infections. Silver nanoparticles are promising antimicrobial agents with activity against biofilm bacteria. Here we describe the synthesis of antimicrobial silver nanoparticles and the measurement of their antimicrobial activity against E. coli colony biofilms, which is a popular in vitro biofilm model for antibiotic assays.

Solvent-free production of phthalated cashew gum for green synthesis of antimicrobial silver nanoparticles

This work describes a solvent-free method for the chemical modification of cashew gum (Anacardium occidentale L.) using phthalic anhydride in different proportions with different reaction times. Four biopolymers were synthesized and characterized by FTIR, NMR, and elemental analysis. A computational chemistry study was conducted to understand better the reaction. Phthalated cashew gum was used in preparation of silver nanoparticles (AgNPs) by a conventional route, using sodium borohydride (NaBH4) as reducing agent, and for green route. AgNPs were evaluated for antimicrobial activity and characterized by UV-Vis spectroscopy, FTIR, nanoparticle tracking analysis, Zeta Potential analysis, and atomic force microscopy. AgNPs produced by the green route had an average size of 51.9 nm and Zeta Potential of -55.8 mV, and AgNPs produced by the conventional method had an average size of 47.7 nm and Zeta Potential of -39.3 mV. AgNPs synthesized using phthalated cashew gum showed antimicrobial activity against Staphylococcus aureus and Escherichia coli.

One-Pot Green Synthesis of Silver Nanoparticles Using the Orchid Leaf Extracts of Anoectochilus elatus: Growth Inhibition Activity on Seven Microbial Pathogens

The development of reliable antibiotics in the fight against multidrug resistant bacteria is a crucial challenge nowadays. Here, we describe a green chemistry approach for the synthesis of antimicrobial silver nanoparticles (AgNPs) employing the leaf extract of the orchid Anoectochilus elatus. Synthesized Ag NPs were studied by UV–visible and ATR-FT-IR spectroscopy, as well as by XRD, SEM and TEM. The UV–Visible spectra of AgNPs exhibited a surface plasmon resonance peak at 420 nm. XRD analysis showed that peaks at 38.09°, 44.59°, 64.67° and 77.54° confirmed the crystalline nature of AgNPs. TEM revealed spherical shapes with an average particle size of 20 nm. Synthesized AgNPs were screened to evaluate their antimicrobial activity against five Gram-negative and two Gram-positive human bacterial pathogens. AgNPs showed effective antibacterial activity against all tested bacterial strains at the concentration of 30–50 μL. Furthermore, the bactericidal efficacy of AgNPs can be useful to develop new eco-friendly antibacterial products to be used for photocatalytic, textile fabric applications, as well as to co-formulate detergents.

Plant Mediated Green Synthesis of Anti-Microbial Silver Nanoparticles—A Review on Recent Trends

Plant Mediated Green Synthesis of Anti-Microbial Silver Nanoparticles—A Review on Recent Trends

Converting a Natural Protein Compartment into a Nanofactory for the Size-Constrained Synthesis of Antimicrobial Silver Nanoparticles.

Engineered biological systems are used extensively for the production of high value and commodity organics. On the other hand, most inorganic nanomaterials are still synthesized via chemical routes. By engineering cellular compartments, functional nanoarchitectures can be produced under environmentally sustainable conditions. Encapsulins are a new class of microbial nanocompartments with promising applications in nanobiotechnology. Here, we engineer the Thermotoga maritima encapsulin EncTm to yield a designed compartment for the size-constrained synthesis of silver nanoparticles (Ag NPs). These Ag NPs exhibit uniform shape and size distributions as well as long-term stability. Ambient aqueous conditions can be used for Ag NP synthesis, while no reducing agents or solvents need to be added. The antimicrobial activity of the synthesized protein-coated or shell-free Ag NPs is superior to that of silver nitrate and citrate-capped Ag NPs. This study establishes encapsulins as an engineerable platform for the synthesis of biogenic functional nanomaterials.

Biomimetic synthesis of antimicrobial silver nanoparticles using in vitro-propagated plantlets of a medicinally important endangered species: Phlomis bracteosa.

In vitro-derived cultures of plants offer a great potential for rapid biosynthesis of chemical-free antimicrobial silver nanoparticles (AgNPs) by enhancing their phytochemical reducing potential. Here, we developed an efficient protocol for in vitro micropropagation of a high-value endangered medicinal plant species, Phlomis bracteosa, in order to explore its biogenic potential in biomimetic synthesis of antimicrobial AgNPs. Murashige and Skoog medium supplemented with 2.0 mg/L thidiazuron was found to be more efficient in inducing optimum in vitro shoot regeneration (78%±4.09%), and 2.0 mg/L indole-3-butyric acid was used for maximum root induction (86%±4.457%). Antimicrobial AgNPs were successfully synthesized by using aqueous extract (rich in total phenolics and flavonoids content) of in vitro derived plantlets of P. bracteosa. Ultraviolet–visible spectroscopy of synthesized AgNPs showed characteristic surface plasmon band in the range of 420–429 nm. The crystallinity, size, and shape of the AgNPs were characterized by X-ray diffraction and scanning electron microscopy. Face-centered cubic AgNPs of almost uniform spherical size (22.41 nm) were synthesized within a short time (1 hour) at room temperature. Fourier-transform infrared spectroscopy revealed that the polyphenols were mainly responsible for reduction and capping of synthesized AgNPs. Energy dispersive X-ray analysis further endorsed the presence of elemental silver in synthesized AgNPs. These biosynthesized AgNPs displayed significantly higher bactericidal activity against multiple drug-resistant human pathogens. The present work highlighted the potent role of in vitro-derived plantlets of P. bracteosa for feasible biosynthesis of antimicrobial AgNPs, which can be used as nanomedicines in many biomedical applications.

In Situ Synthesis of Antimicrobial Silver Nanoparticles within Antifouling Zwitterionic Hydrogels by Catecholic Redox Chemistry for Wound Healing Application.

A multifunctional hydrogel that combines the dual functionality of both antifouling and antimicrobial capacities holds great potential for many bioapplications. Many approaches and different materials have been employed to synthesize such a material. However, a systematic study, including in vitro and in vivo evaluation, on such a material as wound dressings is highly scarce at present. Herein, we report on a new strategy that uses catecholic chemistry to synthesize antimicrobial silver nanoparticles impregnated into antifouling zwitterionic hydrogels. For this purpose, hydrophobic dopamine methacrylamide monomer (DMA) was mixed in an aqueous solution of sodium tetraborate decahydrate and DMA monomer became soluble after increasing pH to 9 due to the complexation between catechol groups and boron. Then, cross-linking polymerization of zwitterionic monomer was carried out with the solution of the protected dopamine monomer to produce a new hydrogel. When this new hydrogel comes in contact with a silver nitrate solution, silver nanoparticles (AgNPs) are formed in its structure as a result of the redox property of the catechol groups and in the absence of any other external reducing agent. The results obtained from TEM and XRD measurements indicate that AgNPs with diameters of around 20 nm had formed within the networks. FESEM images confirmed that the silver nanoparticles were homogeneously incorporated throughout the hydrogel network, and FTIR spectroscopy demonstrated that the catechol moiety in the polymeric backbone of the hydrogel is responsible for the reduction of silver ions into the AgNPs. Finally, the in vitro and in vivo experiments suggest that these mussel-inspired, antifouling, antibacterial hydrogels have great potential for use in wound healing applications.

A comparative antimicrobial activity of Annona Squamosa aqueous leaves extract and its mediated synthesized silver nanoparticles

The synthesis of nanoparticles using plants is a newly evolving research interest in the field of nanotechnology. Medically important plants have high photochemical which is involved in the reduction of silver ions to silver nanoparticles. In this present investigation we explore the environmental benign synthesis of antimicrobial silver nanoparticles using Annona squamosa leaves extract. The fabricated silver nanoparticles were confirmed by colour change from pale yellow to brown colour. UV-vis spectrophotometer shows the surface Plasmon resonance at 460 nm for synthesized silver nanoparticles in the reaction mixture. Scanning Electron Microscope analysis showed that the silver nanoparticles renged in the size from 40-50 nm with spherical shapes. Energy dispersive X-ray spectroscopy elucidates the chemical nature of the synthesized silver nanoparticles which showed a strong peak at the energy of 3 keV for silver. Further, the antimicrobial activities of silver nanoparticles were carried out against pathogenic bacteria and fungi by using agar well diffusion method. The antimicrobial property show high toxicity and inhibition against microbes.

Synthesis of antimicrobial silver nanoparticles through a photomediated reaction in an aqueous environment.

A fast, economical, and reproducible method for nanoparticle synthesis has been developed in our laboratory. The reaction is performed in an aqueous environment and utilizes light emitted by commercially available 1 W light-emitting diodes (λ =420 nm) as the catalyst. This method does not require nanoparticle seeds or toxic chemicals. The irradiation process is carried out for a period of up to 10 minutes, significantly reducing the time required for synthesis as well as environmental impact. By modulating various reaction parameters silver nanoparticles were obtained, which were predominantly either spherical or cubic. The produced nanoparticles demonstrated strong antimicrobial activity toward the examined bacterial strains. Additionally, testing the effect of silver nanoparticles on the human keratinocyte cell line and human peripheral blood mononuclear cells revealed that their cytotoxicity may be limited by modulating the employed concentrations of nanoparticles.

A Novel ‘Green’ Synthesis of Antimicrobial Silver Nanoparticles (AgNPs) by using Garcinia morella (Gaertn) Desr. Fruit Extract

A Novel ‘Green’ Synthesis of Antimicrobial Silver Nanoparticles (AgNPs) by using Garcinia morella (Gaertn) Desr. Fruit Extract

Biological Synthesis of Antimicrobial Silver Nanoparticles by Phaseolus vulgaris Seed Extract

Biological synthesis of silver nanoparticles is generally a time-consuming process in comparison to chemical process. Despite voluminous reports on biological synthesis of silver nano particles, there is still a challenge to develop fast syn thesis of nanoparticles in the range of minutes/seconds through biological route. Several disadvantages are generally being posed by slow biological synthesis of silver nanoparticles including cost of operation. To overcome this difficulty, fast and simple method has been developed for the synthesis of silver nanoparticles, using Phaseolus vulgaris seed extract simply by increasing the temperature. The method is very quick and the color change of the reaction can be observed within 20 seconds. This process was able to synthesize silver nanoparticles within 80 seconds at 100oC which was confirmed by absorption peak at 413.79 nm in UV-visible spectrum. Initially, it was observed that P. vulgaris seed extract was unable to synthesize silver nanoparticles at 37oC even after 24 hours. The silver nanoparticles generated by this method were predominantly spherical in shape and in the range of approximately 4 to 30 nm in size, as characterized by transmission electron microscopy (TEM). On FTIR analysis, it was found that the nanoparticles possessed definite surface exposed groups. Generated silver nanoparticles showed antimicrobial activity against clinical isolates, Escherichia coli and Candida albicans. Thus, this biological process offers a simple, ecofriendly and very fast synthesis of antimicrobial silver nanoparticles.

Biogenic synthesis of antimicrobial silver nanoparticles capped with l-cysteine

The number of medical applications of silver nanoparticles is constantly expanding due to their high bactericidal properties coupled with low toxicity towards mammalian cells. Because of this expanding use of silver nanoparticles, novel methods of synthesis have been developed in order to achieve nanoparticles preparation through inexpensive and environmentally friendly processes; biogenic synthesis of silver nanoparticles is an approach that meets those requirements.In this work, Escherichia coli cultures centrigugates were used to synthesis l-cysteine capped silver nanoparticles. The ratio between AgNO3 and l-cysteine has been proven to affect the size of the nanoparticles: higher amount of l-cysteine returns smaller nanoparticles, but does not affect the percentage of organic matter in the nanoparticles as determined through TGA.The silver nanoparticles prepared had antimicrobial activity against E. coli and Staphylococcus aureus with Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) independent of the nanoparticles size; for both bacterial species the values of MIC and MBC were the same, 0.0432mg/ml for E. coli and 0.0216mg/ml for S. aureus.

Psychrotrophic yeast Yarrowia lipolytica NCYC 789 mediates the synthesis of antimicrobial silver nanoparticles via cell-associated melanin

A psychrotrophic marine strain of the ascomycetous yeast Yarrowia lipolytica (NCYC 789) synthesized silver nanoparticles (AgNPs) in a cell-associated manner. These nanostructures were characterized by UV-Visible spectroscopy and scanning electron microscope-energy dispersive spectrometer (SEM-EDS) analysis. The brown pigment (melanin) involved in metal-interactions was obtained from the cells. This extracted pigment also mediated the synthesis of silver nanoparticles that were characterized by a variety of analytical techniques. The melanin-derived nanoparticles displayed antibiofilm activity. This paper thus reports the synthesis of AgNPs by the biotechnologically important yeast Y. lipolytica; proposes a possible mechanism involved in the synthetic process and describes the use of the bio-inspired nanoparticles as antibiofilm agents.

Evaluation of antibacterial efficacy of phyto fabricated silver nanoparticles using Mukia scabrella (Musumusukkai) against drug resistance nosocomial gram negative bacterial pathogens

Given the fact in the limitation of the therapeutic options for emerging multidrug resistance gram-negative bacteria (MDR-GNB) of respiratory tract infections, the present study was focused on green synthesis of antimicrobial silver nanoparticles (AgNPs) using leaf extract of Mukia scabrella. An obvious color change to brown color and surface plasmon resonance by UV–visible spectroscopy (UV–vis) indicated a well observable peak at 440nm confirming the synthesis of AgNPs. Fourier transform infra-red spectroscopy (FTIR) analysis indicates protein as possible capping agents. Energy dispersive X-ray (EDAX) spectroscopy results showed major signal for elemental silver. X-ray diffraction (XRD) analysis indicates the formation of metallic silver nanomaterials. Transmission electron microscopic (TEM) study showed the nanoparticles in the size range of 18–21nm with spherical shape. Zeta potential analysis showed −21.7mV characteristic for stable AgNPs. The biosynthesized AgNPs exhibited significant antimicrobial activity against MDR-GNB nosocomial pathogens of Acinetobacter sp., Klebsiella pneumoniae and Pseudomonas aeruginosa. Results from the current study suggested that M. scabrella material could be exploited for the fabrication of AgNPs with potential therapeutic applications in nanomedicine especially for nosocomial bacterial infections.

In vitro synthesis of antimicrobial silver nanoparticles by mangroves, saltmarshes and plants of coastal origin

A total of 13 leaf extracts of coastal plants were used for the synthesis of silver nanoparticles and to test the antimicrobial potential of nanoparticles. The highest amount of nanoparticles was obtained by Sesuvium portulacastrum followed by Prosopis chilensis, Hibiscus rosasinensis and Clerodendrum inerme. The synthesised nanoparticles were spherical with variable size ranging from 5 to 20 nm, as evident by transmission electron microscopy. The synthesis of silver nanoparticles was confirmed with X-ray diffraction spectrum. Fourier transform infrared spectroscopy identified the presence of amide I, II and III, aromatic rings, geminal methyls and ether linkages indicating the presence of biomolecules responsible for stabilisation of the silver nanoparticles. Protein bands with molecular weight in a range of 35 to 100 kDa were detected. The nanoparticles inhibited clinical strains of bacteria and fungi with more distinct antifungal activity, which was enhanced when polyvinyl alcohol was added as a stabilising agent.

Analysis of antimicrobial silver nanoparticles synthesized by coastal strains of Escherichia coli and Aspergillus niger

The present study investigated the extracellular biosynthesis of antimicrobial silver nanoparticles by Escherichia coli AUCAS 112 and Aspergillus niger AUCAS 237 derived from coastal mangrove sediment of southeast India. Both microbial species were able to produce silver nanoparticles, as confirmed by X-ray diffraction spectrum. The nanoparticles synthesized were mostly spherical, ranging in size from 5 to 20 nm for E. coli and from 5 to 35 nm for A. niger, as evident by transmission electron microscopy. Fourier transform spectroscopy revealed prominent peaks corresponding to amides I and II, indicating the presence of a protein for stabilizing the nanoparticles. Electrophoretic analysis revealed the presence of a prominent protein band with a molecular mass of 45 kDa for E. coli and 70 kDa for A. niger. The silver nanoparticles inhibited certain clinical pathogens, with antibacterial activity being more distinct than antifungal activity. The antimicrobial activity of E. coli was more pronounced than that of A. niger and was enhanced with the addition of polyvinyl alcohol as a stabilizing agent. This work highlighted the possibility of using microbes of coastal origin for synthesis of antimicrobial silver nanoparticles.