scholarly journals Green Synthesis of Silver Nanoparticles Using Hypericum perforatum L. Extract and Evaluation of Their Antibacterial Activity

2020 ◽  
Vol 71 (2) ◽  
pp. 273-279
Author(s):  
Daniela Gitea ◽  
Andrei Teodorescu ◽  
Carmen Pantis ◽  
Delia Mirela Tit ◽  
Alexa Florina Bungau ◽  
...  

Silver nanoparticles (AgNPs) ranging in size from 1-100 nm show good application potential in many medical fields (therapies, medical devices, molecular diagnostics) due to their antimicrobial properties. The purpose of this study is to characterize from physicochemical perspective the colloidal dispersion obtained through phyto-synthesis. The existence of colloidal silver particles was visually highlighted through Thyndall effect. The bio-reduction of silver ions was analyzed through modern techniques, UV-VIS spectrophotometry and Hyperspectral Microscopy. After getting the colloidal dispersion, its antibacterial activity was proved by sowing on different plates the following types of pathogenic agents: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa. The UV-VIS spectrum for the methanolic extract with 10% H. perforatum L. and for the silver colloidal dispersions was achieved, observing a max at 455 nm. The hyperspectral images were achieved observing the shape, conformation, and the size of the obtained particles. During the antibacterial efficacy testing on those three strains of pathological agents, in all situations, the colloidal dispersion had a promising antimicrobial effect.

2010 ◽  
Vol 10 ◽  
pp. 29-37 ◽  
Author(s):  
Maryam Jokar ◽  
Russly Abdul Rahman ◽  
Nor Azowa Ibrahim ◽  
Luqman Chuah Abdullah ◽  
Tan Chin Ping

Silver nanoparticles are of interest due to their unique physicochemical and antimicrobial properties. The nanoparticles were produced by chemical reduction using short chain polyethylene glycol (PEG) as reducing agent, solvent and stabilizer in absence of other chemicals. Silver nanoparticles were separated from colloidal dispersion by ultra centrifuge at 14000 rpm. The reduction of silver ion (Ag+) to silver nanoparticles (Agº) was monitored by pH measurement and UV-visible spectroscopy of colloidal dispersion at fixed intervals. Silver nanoparticles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and diphenyl-picrylhydrazyl (DPPH) radical scavenging method. Antimicrobial activity of silver nanoparticles was investigated against Escherichia coli, Staphylococcus aureus and Vibrio parahaemolyticus by agar plate test. Results indicated 51.5% conversion efficiency of silver ions to silver nanoparticles. Colloidal dispersion containing 4.12 mg/ml silver nanoparticles showed uniform size of 5.5 ± 1.1 nm with a typical visible spectra band at 447 nm. Silver nanoparticles showed significant (p < 0.05) antimicrobial efficiency and with concentration of 100 ppm resulted in 46.22%, 66.51% and 69.06% inhibition against S. aureus, E. coli and V. parahaemolyticus, respectively. The nanoparticles were also found to reduce DPPH free radical up to 88.9%. Results of this study proved that the silver nanoparticles produced by polyethylene glycol possess antimicrobial and antioxidant activity.


2007 ◽  
Vol 15 (5) ◽  
pp. 357-363 ◽  
Author(s):  
Dirk Pohle ◽  
Cornelia Damm ◽  
Johanna Neuhof ◽  
Alfons Rösch ◽  
Helmut Münstedt

Materials exhibiting an antimicrobial effect are especially advantageous for medical textiles which are in very close and long-term contact with human skin. Orthopaedic stockings made of terry cotton and polyamide were coated with silver nanoparticles by a simple dip coating process under mild conditions. Both textiles released silver ions over at least 28 days. The silver ion release for both materials is governed by diffusion. The amount of silver ions released by the cotton textile was higher than by the nylon stockings by about a factor of 4. The reason was a larger silver reservoir in the cotton sample, because it contains much more silver than the nylon fabric. As expected from the results of the Ag+ release tests, both these silver coated textiles were active against Escherichia coli.


Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 978 ◽  
Author(s):  
Lian-Hua Fu ◽  
Qing-Long Gao ◽  
Chao Qi ◽  
Ming-Guo Ma ◽  
Jun-Feng Li

Silver-based antimicrobial nanomaterials are considered as the most promising antibacterial agents owing to their outstanding antimicrobial efficacy and their relatively low toxicity to human beings. In this work, we report on a facile and environment-friendly microwave-hydrothermal method to prepare cellulose/Ag nanocomposites using hemicellulose as the reductant. The influences of the microwave-hydrothermal heating time and temperature, as well as the hemicellulose concentration on the formation of cellulose nanocomposites, were investigated in detail. Experimental results indicated that the hemicellulose was an effective reductant for silver ions, with higher temperature and longer heating time favoring the formation of silver with higher crystallinity and mass content in the nanocomposites. Moreover, the antimicrobial properties of the as-prepared cellulose/Ag nanocomposites were explored using Gram-positive S. aureus ATCC 6538 and Gram-negative E. coli HB 101 by both disc diffusion method and agar dilution method, and the nanocomposites showed excellent antibacterial activity. These results demonstrate that the as-prepared cellulose/Ag nanocomposites, as a kind of antibacterial material, are promising for applications in a wide range of biomedical fields.


Author(s):  
Shyla Marjorie Haqq ◽  
Amit Chattree

  This review is based on the synthesis of silver nanoparticles (AgNPs) using a green approach which is biofabricated from various medicinal plants. AgNPs were prepared from the various parts of the plants such as the flowers, stems, leaves, and fruits. Various physiochemical characterizations were performed using the ultraviolet (UV)-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, transmission electron microscopy, and energy dispersive spectroscopy. AgNPs were also used to inhibit the growth of bacterial pathogens and were found to be effective against both the Gram-positive and Gram-negative bacteria. For the silver to have antimicrobial properties, it must be present in the ionized form. All the forms of silver-containing compounds with the observed antimicrobial properties are in one way or another source of silver ions. Although the antimicrobial properties of silver have been known, it is thought that the silver atoms bind to the thiol groups in enzymes and subsequently leads to the deactivation of enzymes. For the silver to have antimicrobial properties, it must be present in the ionized form. The study suggested that the action of the AgNPs on the microbial cells resulted into cell lysis and DNA damage. AgNPs have proved their candidature as a potential antibacterial against the multidrug-resistant microbes. The biological agents for synthesizing AgNPs cover compounds produced naturally in microbes and plants. Reaction parameters under which the AgNPs were being synthesized hold prominent impact on their size, shape, and application. Silver nanoparticle synthesis and their application are summarized and critically discussed in this review.


2019 ◽  
Vol 31 (12) ◽  
pp. 2804-2810
Author(s):  
Anti Kolonial Prodjosantoso ◽  
Oktanio Sigit Prawoko ◽  
Maximus Pranjoto Utomo ◽  
Lis Permana Sari

In this article, the synthesis of silver nanoparticles through a reduction reaction process using Salacca zalacca extract is reported. The AgNPs were characterized using X-ray diffraction, transmission electron microscopy, Fourier transform infrared and UV-visible spectrophotometry methods. The AgNPs antibacterial activity was determined against of Gram-positive bacteria (Staphylococcus epidermidis) and Gram-negative bacteria (Escherichia coli). The main functional groups contained in Salacca zalacca extract are carbonyl, hydroxyl and nitrile groups, which are believed to reduce the silver ions to metal. The surface plasmon resonance values of brownish red AgNPs are in the range of 410 nm to 460 nm. The structure of AgNPs is face centered cubic (FCC). The diameter of silver nanoparticles crystallite is 14.2 ± 2.6 nm. The AgNPs growth inhibition zones of Escherichia coli and Staphylococcus epidermidis are 9.6 mm and 9.2 mm, respectively.


2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Siraj Shaik ◽  
Madhusudana Rao Kummara ◽  
Sudhakar Poluru ◽  
Chandrababu Allu ◽  
Jaffer Mohiddin Gooty ◽  
...  

A series of starch-co-poly(acrylamide) (starch-co-PAAm) hydrogels were synthesized by employing free radical redox polymerization. A novel green approach, Tridax procumbens (TD) leaf extract, was used for reduction of silver ions (Ag+) into silver nanoparticles in the starch-co-PAAm hydrogel network. The formation of silver nanoparticles was confirmed by UV-visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (X-RD) studies. 22% of weight loss difference between hydrogel and silver nanocomposite hydrogel (SNCH) clearly indicates the formation of silver nanoparticles by TGA. TEM images indicate the successful incorporation of silver nanoparticles ranging from 5 to 10 nm in size and spherical in shape with a narrow size distribution. These developed SNCHs were used to study the antibacterial activity by inhibition zone method against gram-positive and gram-negative bacteria such as Bacillus and Escherichia coli. The results indicated that these SNCHs can be used potentially for biomedical applications.


2021 ◽  
Author(s):  
Parvaneh Mohamadinia ◽  
Navideh Anarjan

Abstract Hydrogels are specific groups of polymers that are highly swellable in aqueous solutions, despite their water-in-soluble structures. Thus, they are promising drug delivery systems attributable to their unique characteristics such as high hydrophilicity, high controllability, facile production routines and, good biocompatibility. The aim of this research was the preparation of sodium alginate/acrylic acid composite hydrogels conjugated to silver nanoparticles to deliver the cephalexin as a model antibiotic compound. The reduction of silver ions into silver nanoparticles as well as the stabilization of created nanoparticles ensued simultaneously with hydrogel backbone formulation during microwave irradiation and monomer cross-linking processes. The impact of acrylic acid and silver ions concentrations and also the radiation time of microwave were then investigated on the main characteristics of hydrogels, namely, swelling ratio, gel fraction, cephalexin load and, antibacterial activity. The results indicated that the hydrogels’ characteristics could be significantly predicted by studied all independent parameters, through various second-order polynomial models. The multiple optimization analysis suggested that the prepared hydrogels using 7.8 g acrylic acid and 1.5 g silver nitrate and 1 min microwave radiation could give the best hydrogels with the highest swelling degree, gel fraction, cephalexin absorption and, antibacterial activity. The morphology and either absorption or release kinetics of cephalexin by/from the optimum prepared hydrogels were also investigated. No significant differences between the experimental and predicted data was confirmed the suitability of the suggested models.


2020 ◽  
Vol 234 (3) ◽  
pp. 531-540
Author(s):  
Saba Ghamipoor ◽  
Faeze Fayyazi ◽  
Saeed Bahadorikhalili

AbstractIn this work, green synthesis of silver nanoparticles is described by phytochemical reducing silver nitrate aqueous solution using Anthemis nobilis. For this purpose, Anthemis nobilis extract was used for the synthesis of silver nanoparticles as both surfactant and reducing agent. Green synthesis method is a good alternative to physical and chemical methods, since it is fast, simple, environmentally-friendly and economic. The produced nanoparticles are identified using FE-SEM, EDX, and FT-IR and Uv/Vis techniques. Formation of silver nanoparticles is verified in 430–420 nm range. Reduction of silver ions by hydroxyl functional group is also confirmed by FT-IR device. EDX device confirms the presence of a peak for Ag element without any impurity peak. Silver nanoparticles are identified by FE-SEM device and found to have average size between 17 and 42 nm. Also, the antibacterial activity of the synthesized nanoparticles is compared with that of staphyloccusaureus and pseudomonasa aeruginosa and the maximum inhibitory activity against the bacteria is obtained using 1 mM nitrate solution.


2014 ◽  
Vol 264 ◽  
pp. 418-422 ◽  
Author(s):  
Duangkamon Jiraroj ◽  
Sukkaneste Tungasmita ◽  
Duangamol N. Tungasmita

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