scholarly journals DETERMINATION OF OPTIMAL PARAMETERS FOR SYNTHESIS OF SILVER NANOPARTICLES STABILIZED WITH POLYETHYLENE GLYCOL

2021 ◽  
pp. 32-43
Author(s):  
Андрей Владимирович Блинов ◽  
Алексей Алексеевич Гвозденко ◽  
Анастасия Александровна Блинова ◽  
Анна Витальевна Кобина ◽  
Алексей Борисович Голик ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Polyethylene Glycol ◽  
Silver Nitrate ◽  
Chemical Reduction ◽  
Reaction System ◽  
Correlation Spectroscopy ◽  
Metallic Silver ◽  
Chemical Hardness ◽  
Optimal Parameters ◽  
Characteristic Absorption Band

В рамках данной работы представлены результаты исследования влияния концентраций стабилизатора и прекурсора на процесс синтеза наночастиц серебра. В качестве прекурсора использован нитрат серебра, а в качестве стабилизатора -полиэтиленгликоль с молекулярной массой от 200 до 600 Да. Синтез осуществляли методом химического восстановления в водной среде. Полученные образцы исследовали фотонно-корреляционной спектроскопией и спектрофотометрией. Установлено наличие характеристической полосы поглощения на 400 нм в спектрах поглощения всех образцов наноразмерного серебра, стабилизированного полиэтиленгликолем, что обусловлено возникновением поверхностного плазмонного резонанса у металлических наночастиц серебра. Также установлено, что при наибольшей и наименьшей концентрации стабилизатора, равных, соответственно, 0. 005 и 0,1 мас. %, в реакционной системе наблюдается формирование крупных частиц серебра со средним гидродинамическим радиусом от 132 до 1900 нм. В результате определены оптимальные параметры синтеза агрегативно устойчивых наночастиц серебра: концентрация нитрата серебра С (AgNO) = 0,05 M и концентрация полиэтиленгликоля, равная 0,01 - 0,05 %. Проведено компьютерное квантовохимическое моделирование. Установлено, что энергетически выгодным является взаимодействие атома серебра с концевой гидроксогруппой в молекуле полиэтиленгликоля в элементарном акте взаимодействия при стабилизации наночастиц серебра данным полимером. Данный тип взаимодействия характеризуется абсолютной химической жесткостью, равной ƞ = 0,146 эВ, и внутренней энергией E = -2048,34 ккал / моль. Within the framework of this work, the results are presented of a study of the effect of the concentrations of the stabilizer and precursor on the synthesis of silver nanoparticles. Silver nitrate was used as a precursor, and polyethylene glycol with a molecular weight from 200 to 600 Da was used as a stabilizer. The synthesis was carried out by the method of chemical reduction in an aqueous medium. The obtained samples were investigated by photon correlation spectroscopy and spectrophotometry. The presence of a characteristic absorption band at 400 nm in the absorption spectra of all samples of nanosized silver stabilized with polyethylene glycol was established, which is due to the appearance of surface plasmon resonance in metallic silver nanoparticles. It was also found that at the highest and lowest concentration of the stabilizer, equal, respectively, 0,005 and 0,1 mass. %, the formation of large silver particles with an average hydrodynamic radius from 132 to 1900 nm is observed in the reaction system. As a result, the optimal parameters for the synthesis of aggregatively stable silver nanoparticles were determined: the concentration of silver nitrate C(AgNO) = 0,05 M and the concentration of polyethylene glycol equal to 0,01 - 0,05 %. Computer quantum-chemical modeling is carried out. It is found that the interaction of the silver atom with the terminal hydroxogroup in the polyethylene glycol molecule in the elementary act of interaction during the stabilization of silver nanoparticles by this polymer is energetically advantageous. This type of interaction is characterized by an absolute chemical hardness equal to ƞ = 0,146, and an internal energy of E = -2048,34 kcal / mol.

scholarly journals Subinhibitory concentrations of silver nanoparticles and silver nitrate on the adaptative and cross-resistance to antibiotics on bovine mastitis pathogens

2021 ◽  
Vol 51 (12) ◽  
Author(s):  
Patrícia Érica Fernandes ◽  
Roberta Barbosa Teodoro Alves ◽  
Natan de Jesus Pimentel-Filho ◽  
João Paulo Natalino de Sá ◽  
Hilário Cuquetto Mantovani ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Chemical Reduction ◽  
Bovine Mastitis ◽  
Cross Resistance ◽  
Ag Nps ◽  
Adaptive Resistance ◽  
Subinhibitory Concentrations ◽  
Mastitis Pathogens ◽  
Sensitivity Profile

ABSTRACT: Biocides and/or antibiotics used in subinhibitory concentrations can promote the development of adaptive resistance or even cross-resistance in microorganisms. However, studies on these responses following silver treatments are scarce in the literature. Silver-based compounds, including silver nanoparticles (Ag-NPs), can be an alternative in the prevention and treatment of bovine mastitis. Thus, this research evaluated the effect of subinhibitory dosages of Ag-NPs and Ag+ ions from silver nitrate (AgNO3) on Staphylococcus aureus and Escherichia coli isolated from milk of cows with mastitis. Ag-NPs were synthesized by chemical reduction using AgNO3 and sodium citrate and the minimum inhibitory concentration (MIC) of Ag-NPs and Ag+ ions on the mastitis pathogens were determined. Isolates were exposed to subinhibitory concentrations of Ag-NPs or AgNO3 for 10 consecutive days to verify the development of adaptive resistance evaluated by changes in the MIC values. The development of cross-resistance with antibiotics was also studied, being verified by comparing the sensitivity profile of treated cells with non-treated cells. AgNO3 was more effective against all isolates. There was no change in the MIC values or in the antibiotic sensitivity profile for both bacteria following consecutive exposure to subinhibitory dosages of Ag-NPs or AgNO3, indicating that silver was not able to select adaptive resistance or cross resistance to the tested antibiotics. The potential of silver presented by these results is favorable to the continuity of studies aiming to elaborate silver-based therapies for the treatment of bovine mastitis.

Green Synthesis and Characterization of Silver Nanoparticles by Using Aloe Vera Leaf Extract to Study the Effects of Synthesis Parameters

2016 ◽  
Vol 860 ◽  
pp. 179-184
Author(s):  
Asif Rahman ◽  
A.K.M. Bazlur Rashid ◽  
Md Abdul Aziz Antor ◽  
Md Ashif Anwar ◽  
Roisul Hasan Galib
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Leaf Extract ◽  
Nitrate Solution ◽  
Aloe Vera ◽  
Bath Temperature ◽  
Heating Time ◽  
Water Bath ◽  
Metallic Silver ◽  
Nanoparticle Suspension

In this research silver nanoparticles were synthesized by reducing silver nitrate solution using aloe vera leaf extract as reducing agent. The synthesized nanoparticles had been characterized and the effects of different parameters of synthesis had been evaluated. Silver nanoparticles began to form just after reaction and the whole reduction reaction was completed within 3 hours. The color changed from transparent to dark brown of the aqueous salt solution. Later the nanoparticles were separated out from the mixture by ultra-centrifugation. Here the effects of water bath temperature, the effects of heating time at that certain temperature and the effects of changing concentration of silver nitrate on the size of the synthesized nanoparticles was studied. The particle size and morphology of the synthesized silver nanoparticles were identified by SEM analysis. It was found to be 12-200 nm in different parameters (12-25 nm at the best condition) and spherical in shape. It was also found that the size of silver nanoparticles increased with increasing water bath temperature, increasing heating time and increasing silver nitrate concentration. Energy dispersive X-ray spectroscopy was used to confirm that the nanoparticle suspension contains nothing but metallic silver. It was found that 70% of elemental silver nanoparticles were present.

scholarly journals Characterization and Biocompatibility Properties of Silver Nanoparticles Produced Using Short Chain Polyethylene Glycol

2010 ◽  
Vol 10 ◽  
pp. 29-37 ◽  
Author(s):  
Maryam Jokar ◽  
Russly Abdul Rahman ◽  
Nor Azowa Ibrahim ◽  
Luqman Chuah Abdullah ◽  
Tan Chin Ping
Keyword(s):  
Silver Nanoparticles ◽  
Polyethylene Glycol ◽  
Chemical Reduction ◽  
Radical Scavenging ◽  
Agar Plate ◽  
Antimicrobial Properties ◽  
Silver Ions ◽  
Colloidal Dispersion ◽  
Short Chain ◽  
Uniform Size

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.

Silver Nanoparticles/Montmorillonite Composites Prepared Using Nitrating Reagent at Water and Glycerol

2008 ◽  
Vol 8 (6) ◽  
pp. 3050-3058 ◽  
Author(s):  
Marta Valášková ◽  
Gražyna Simha Martynková ◽  
Jana Lešková ◽  
Pavla Čapková ◽  
Volker Klemm ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Interlayer Space ◽  
Exchangeable Cations ◽  
Metallic Silver ◽  
Transmission Electron ◽  
Modeled Structure ◽  
Silicate Layers ◽  
20 Nm ◽  
Nanoparticles Of Silver

Three procedures (P) were applied to prepare silver nanoparticles on natural Ca-montmorillonite (MT). The intercalation of the montmorillonite with silver nitrate in aqueous solution (P1), the intercalation of the montmorillonite with silver nitrate in glycerol (P2) and the successive combination of both P1 and P2methods resulted to P3 method. X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier Transform Infrared (FTIR) spectroscopy and the molecular modeling were employed to characterize silver nanoparticles and montmorillonite nanocomposite. The P1 produced MT-1 composite with 2.3 wt% Ag and the partially collapsed layered structure. Nanoparticles of silver larger than 20 nm with a lot of planar defects were randomly distributed on the MT-1 surface; nanoparticles smaller than 20 nm were oriented to the montmorillonite substrate. The MT-2 composite from P2 contained only 1 wt% of Ag. The molecular simulation model of MT-2 showed the interlayer space with the exchangeable cations and metallic silver atoms arrangement within the glycerol bilayer. The P3 produced composite MT-3 that contained 2.4 wt% Ag. The nanoparticles > 20 nm size had a well-defined geometry, very small nanoparticles were amorphous. The modeled structure showed the exchangeable cations, Ag+ and Ag0 located close to the silicate layers and monolayer of glycerol molecules in the interlayer space.

scholarly journals A New Method for the Deposition of Metallic Silver on Porous Ceramic Water Filters

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Kathryn N. Jackson ◽  
James A. Smith
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Removal Rate ◽  
Aqueous Suspension ◽  
Porous Ceramic ◽  
New Method ◽  
Metallic Silver ◽  
E Coli ◽  
Filter Performance ◽  
Continuous Feed

A new method of silver application to a porous ceramic water filter used for point-of-use water treatment is developed. We evaluated filter performance for filters manufactured by the conventional method of painting an aqueous suspension of silver nanoparticles onto the filter and filters manufactured with a new method that applies silver nitrate to the clay-water-sawdust mixture prior to pressing and firing the filter. Filters were evaluated using miscible displacement flow-through experiments with pulse and continuous-feed injections of E. coli. Flow characteristics were quantified by tracer experiments using [3H]H2O. Experiments using pulse injections of E. coli showed similar performance in breakthrough curves between the two application methods. Long-term challenge tests performed with a continuous feed of E. coli and growth medium resulted in similar log removal rates, but the removal rate by nanosilver filters decreased over time. Silver nitrate filters provided consistent removal with lower silver levels in the effluent and effective bacterial disinfection. Results from continued use with synthetic groundwater over 4 weeks, with a pulse injection of E. coli at 2 and 4 weeks, support similar conclusions—nanosilver filters perform better initially, but after 4 weeks of use, nanosilver filters suffer larger decreases in performance. Results show that including silver nitrate in the mixing step may effectively reduce costs, improve silver retention in the filter, increase effective lifespan, and maintain effective pathogen removal while also eliminating the risk of exposure to inhalation of silver nanoparticles by workers in developing-world filter production facilities.

Antibacterial Potential of Silver Nanoparticles Capped with Poly(4-styrenesulfonic acid-co-maleic acid) Polymer

2015 ◽  
Vol 1088 ◽  
pp. 64-68 ◽  
Author(s):  
Hathaichanok Tamiyakul ◽  
Somboon Tanasupawat ◽  
Stephan Thierry Dubas ◽  
Warangkana Warisnoicharoen
Keyword(s):  
Staphylococcus Aureus ◽  
Silver Nanoparticles ◽  
Maleic Acid ◽  
Chemical Reduction ◽  
Spherical Particles ◽  
Metallic Silver ◽  
Gram Negative Bacteria ◽  
Bacterial Strains ◽  
Gram Negative ◽  
Antibacterial Potential

Antibacterial potential of metallic silver nanoparticles (AgNPs) is considered to be influenced by their size and stability. In this study, the stable AgNPs capped with poly (4-styrenesulfonic acid-co-maleic acid) or PSSMA were successfully synthesized by using a chemical reduction method. The PSSMA-stabilized AgNPs (PSSMA-AgNPs) were characterized and tested for antibacterial activity against eight bacterial strains. Transmission electron microscopic studies showed that PSSMA-AgNPs were monodisperse spherical particles with an average size of 5.21 nm. From bacterial growth curve studies, PSSMA-AgNPs exhibited an antibacterial effect on Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 6538p, Staphylococcus aureus ATCC 43300, Staphylococcus epidermidis ATCC 12228 and Bacillus subtilis ATCC 6633) and Gram-negative bacteria (Escherichia coli ATCC 25922, Enterobacter aerogenes ATCC 13048 and Pseudomonas aeruginosa ATCC 27853). Moreover, the Gram-negative bacteria were found to be more susceptible to the AgNPs.

Synthesis of Monodispersed Lauric Acid Capped Silver Nanoparticles by Wet-Chemical Reduction Method

2013 ◽  
Vol 477-478 ◽  
pp. 1246-1252 ◽  
Author(s):  
Chun Fa Dong ◽  
Xiang Lin Zhang ◽  
Chuan Liang Cao ◽  
Hao Cai
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Reaction Temperature ◽  
Lauric Acid ◽  
Chemical Reduction ◽  
Mass Ratio ◽  
Chemical Reduction Method ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical

Silver nanoparticles with narrow distribution were prepared by a simple route in water in presence of lauric acid as the capping agents. The morphology and crystal structure of as-synthesized silver nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The mass ratio of lauric acid and silver nitrate, the reaction temperature play important roles on the morphology and size of the silver nanoparticles. Well-dispersed silver nanopartilces with diameter of 8 nm were obtained when the mass ratio of lauric acid and silver nitrate was 1.2:1 and the reaction temperature was room temperature. It is also confirmed that the sol system was monodisperse nanosilver sol.

scholarly journals Synthesis of silver nanoparticles from electronic scrap by chemical reduction

2021 ◽  
Author(s):  
Abolhassan Najafi ◽  
Mahdi Khoeini ◽  
Gholamreza Khalaj ◽  
Amirhossein Sahebgharan
Keyword(s):  
Silver Nanoparticles ◽  
Silver Nitrate ◽  
Chemical Reduction ◽  
Electronic Waste ◽  
Nitrate Solution ◽  
Silver Nitrate Solution ◽  
Main Peak ◽  
Fcc Structure ◽  
Uniform Particle Size

Abstract In the present research, the use of electronic waste in the synthesis of silver nanoparticles was investigated. For this purpose, electronic scraps were used as a consumable part to synthesize silver nanoparticles. The results revealed that by optimizing the time and temperature of the dissolution process using nitric acid solution up to 90%, silver can be extracted from these parts. The temperature of 60°C and the duration of one hour were determined as the optimum conditions for this phase. Afterward, the synthesis of silver nanoparticles was checked using silver nitrate solution. The results indicated that the concentration of initial silver nitrate had a significant impact on the quality of the final product so that the best conditions for the synthesis of silver nanoparticles with suitable properties were provided at 1 molar concentration. Phase studies indicated that the main phase of the synthesized silver particles had an FCC structure and no unwanted phase was observed. Ultraviolet-visible analysis of the synthesized powder revealed that the main peak for the silver nanoparticles appeared in the wavelength range of 400 to 450 nm. DLS analysis revealed that precursor's particles inside the sol were below 15 nm. Based on AFM and TEM investigations, the particles synthesized under these conditions had nanometric spherical morphology with uniform particle size distribution.

Synthesis and Characterization of Silver Nanoplates by a Seed-mediated Method

2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Mai Ngọc Tuan Anh
Keyword(s):  
Hydrogen Peroxide ◽  
Silver Nanoparticles ◽  
Ascorbic Acid ◽  
Silver Nitrate ◽  
Sodium Borohydride ◽  
Trisodium Citrate ◽  
Synthesis And Characterization ◽  
Silver Nanoplates ◽  
Seed Mediated

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag\(^+\) ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods.

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