Evolution Analysis of Silver Nanoparticles Synthesised by Lactam Reduction: A Case Study of ϵ-Caprolactam

2018 ◽  
Vol 71 (8) ◽  
pp. 587 ◽  
Author(s):  
Na Zhang ◽  
Jianping Duan ◽  
Dajiang Zhao ◽  
Guisheng Yang
Keyword(s):  
Silver Nanoparticles ◽  
Size Distribution ◽  
Ostwald Ripening ◽  
Silver Ions ◽  
Reducing Agents ◽  
Ag Nps ◽  
Second Stage ◽  
Evolution Analysis ◽  
Ostwald Ripening Mechanism

Without using protecting agent and solvent, silver nanoparticles (Ag NPs) were synthesised by using lactams as reducing agents. Being the most commercially available lactam, ϵ-caprolactam (CL) was taken as a model to illustrate the evolution of Ag NPs in the medium of lactams. The results showed that there were two different stages involved in the Ag NP evolution process. In the first stage, particles were stabilised against further coalescence at a smaller size (< 5 nm) because of face-bound CL. In the second stage, the Ostwald ripening mechanism cooperated with continuous reduction of residual silver ions, which resulted in the resultant particles being distributed with different size distribution. The participation of CL in the reducing and protecting procedures raised a complex evolution of Ag NPs.

Preparation of Triangular Silver Nanoparticles Using Polyvinyl Pyrrolidone with Different Concentration

2013 ◽  
Vol 873 ◽  
pp. 206-210
Author(s):  
Kai Li ◽  
Rao Fu ◽  
Qing Ran Gao ◽  
Ai Wei Tang ◽  
Ying Feng Wang
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Silver Nanoparticles ◽  
Driving Force ◽  
Ostwald Ripening ◽  
Polyvinyl Pyrrolidone ◽  
Protective Agent ◽  
Ag Nps ◽  
Transmission Electron ◽  
Uv Visible

This paper continues our previous work on preparation of triangular silver nanoparticles. The method proceeds with reaction of silver nitrate with hydrazine hydrate in the presence of polyvinyl pyrrolidone in aqueous solution. Effects of the concentration of PVP on the morphologies of Ag NPs were systematically investigated. The obtained Ag NPs were characterized by transmission electron microscopy and UV-visible spectrophotometer. The results showed that, triangular Ag NPs with edge lengths in the range of 50-200 nm were obtained using PVP as protective agent with lower concentration. As the concentration of PVP increased, spherical Ag NPs with their sizes about 6.2 nm were prepared and triangular Ag NPs were not obtained. The formation mechanism of triangular Ag NPs has been studied. Ostwald ripening is the driving force on the conversion of spherical Ag NPs to triangular Ag NPs in the presence of PVP.

Silver nanoparticles used to counter Monilinia fructicola fungicide-resistance and reduce fungicide environmental footprint 

2021 ◽  
Author(s):  
Constantinos Chrysikopoulos ◽  
Anastasios A. Malandrakis ◽  
Nektarios Kavroulakis ◽  
Anthi Stefanarou
Keyword(s):  
Silver Nanoparticles ◽  
Control Plant ◽  
Resistance Mutation ◽  
Silver Ions ◽  
Apple Fruit ◽  
Ag Nps ◽  
Gene Target ◽  
Benzimidazole Fungicides

&lt;div&gt;&lt;span&gt;The potential of silver nanoparticles (Ag-NPs) to control plant pathogen &lt;em&gt;Monilia&lt;/em&gt;&lt;em&gt;fructicola &lt;/em&gt;and to deter environmental contamination by reducing fungicide doses was evaluated &lt;em&gt;in vitro &lt;/em&gt;and &lt;em&gt;in vivo. &lt;/em&gt;&amp;#160;&lt;/span&gt;F&lt;span&gt;ungitoxicity screening &lt;/span&gt;of&amp;#160;&lt;em&gt;&lt;span&gt;M. fructicola&amp;#160;&lt;/span&gt;&lt;/em&gt;&lt;span&gt;isolates resulted in the detection of 18 benzimidazole-resistant (BEN-R) isolates with reduced sensitivity to fungicides &amp;#160;thiophanate methyl (TM)&amp;#160; and carbendazim. All resistant isolates caried the E198A resistance mutation in their &lt;/span&gt;&lt;em&gt;&lt;span&gt;&amp;#946;&lt;/span&gt;-&lt;/em&gt;tubulin gene, target site of the benzimidazole fungicides.&amp;#160;&lt;span&gt;Ag-NPs could effectively control both sensitive (BEN-S) and resistant isolates while the combination of Ag-NPs with TM significantly enhanced their fungitoxic effect both &lt;em&gt;in vitro&amp;#160;&lt;/em&gt;and in apple fruit tests. The positive correlation observed between Ag-NPs and TM+Ag-NPs treatments indicates a mixture-enhanced Ag-NPs activity/availability as a possible mechanism of synergy. No correlation between Ag-NPs&amp;#160; and AgNO&lt;sub&gt;3&amp;#160;&lt;/sub&gt;could&amp;#160; be found suggesting difference(s) in the fungitoxic mechanism of action between Nps and their bulk/ionic counterparts. Indications of the involvement of energy (ATP) metabolism in the mode of action of Ag-NPs were also evident by the synergy observed between Ag-NPs and the &lt;/span&gt;oxidative phosphorylation&lt;span&gt;-uncoupler fluazinam (FM) against both BEN-R and BEN-S phenotypes. The role of silver ions release on the inhibitory action of Ag-NPs against the fungusis probably limited since the AgNPs/NaCl combination enhanced fungitoxicity, a fact that could not be justified by the expected binding of silver with chlorine ions. Concluding, Ag-NPs can be effectively used as a means of controlling both BEN-S and BEN-R &lt;em&gt;M.&amp;#160;&lt;/em&gt;&lt;em&gt;fructicola&amp;#160;&lt;/em&gt;isolates &lt;/span&gt;while&amp;#160;&lt;span&gt;their combination with conventional fungicides should aid anti-resistant strategies and reduce the environmental impact of synthetic fungicides by reducing effective doses to the control the pathogen.&lt;/span&gt;&lt;/div&gt;

scholarly journals Silver Nanoparticles Stimulates Spermatogenesis Impairments and Hematological Alterations in Testis and Epididymis of Male Rats

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1063 ◽  
Author(s):  
Janet Olayemi Olugbodi ◽  
Oladipupo David ◽  
Ene Naomi Oketa ◽  
Bashir Lawal ◽  
Bamidele Joseph Okoli ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Hematological Parameters ◽  
Silver Ions ◽  
Thiol Group ◽  
Sperm Parameters ◽  
Male Rats ◽  
Ag Nps ◽  
Hematological Indices ◽  
Electron Microscopies ◽  
Pharmaceutical Application

The potential pharmaceutical application of nanoparticles has led to the toxicity within the male reproductive system. In the present study, the effects of silver nanoparticles (Ag-NPs) on hematological parameters, free radical generation, antioxidant system, sperm parameters, and organ histo-morphometry in male rats were investigated. Ag-NPs were produced by the reduction of silver ions, while the formation of which was monitored by UV–visible spectrophotometry. Zeta potential, transmission, and scanning electron microscopies were applied for the characterization of AgNPs. A total of 30 rats were divided into 6 groups and were sub-dermally exposed to Ag-NPs at the dosage of 0 (control), 10, and 50 mg/kg bodyweight (bw) doses for either 7 or 28 days. Ag-NP administration altered hematological indices and caused dose-dependent decreases in sperm motility, velocity, kinematic parameters, concentrations of luteinizing hormone, follicle-stimulating hormone, and testosterone. In the epididymis and testis, the concentrations of malondialdehyde and peroxide increases while superoxide dismutase, catalase, reduced glutathione, and total thiol group decreases. These findings suggest that Ag-NP triggered hormonal imbalance and induce oxidative stress in testis and epididymis; which negatively affect sperm parameters of male rats.

Core–Shell γ-Fe2O3/SiO2/PCA/Ag-NPs Hybrid Nanomaterials as a New Candidate for Future Cancer Therapy

2014 ◽  
Vol 13 (01) ◽  
pp. 1450008 ◽  
Author(s):  
R. Soleyman ◽  
A. Pourjavadi ◽  
N. Masoud ◽  
A. Varamesh
Keyword(s):  
Silver Nanoparticles ◽  
Cancer Therapy ◽  
Silver Ions ◽  
Core Shell ◽  
Capping Agent ◽  
Hybrid Nanomaterials ◽  
Ag Nps ◽  
Core Nanoparticles ◽  
Size And Structure

In the current study, γ- Fe 2 O 3/ SiO 2/ PCA / Ag -NPs hybrid nanomaterials were successfully synthesized and characterized. At first, prepared γ- Fe 2 O 3 core nanoparticles were modified by SiO 2 layer. Then they were covered by poly citric acid (PCA) via melting esterification method as well. PCA shell acts as an effective linker, and provides vacancies for conveying drugs. Moreover, this shell as an effective capping agent directs synthesis of silver nanoparticles ( Ag -NPs) via in situ photo-reduction of silver ions by sunlight-UV irradiation. This system has several benefits as a suitable cancer therapy nanomaterial. Magnetic nanoparticles (MNPs) can guide Ag -NPs and drugs to cancer cells and then Ag -NPs can affect those cells via Ag -NPs anti-angiogenesis effect. Size and structure of the prepared magnetic hybrid nanomaterials were characterized using FTIR and UV-Vis spectra, AFM and TEM pictures and XRD data.

scholarly journals Copolymerization of Quinazolinone Derivatives With Styrene, Methyl Methacrylate and Their Silver Nanocomposites for Biological Applications

2021 ◽  
Author(s):  
Karim Samy El-Said ◽  
Ahmed Ahmed El-Barbary ◽  
Hazem M. ElKholy ◽  
Ahmed S. Haidyrah ◽  
Mohamed Betiha ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Methyl Methacrylate ◽  
Silver Ions ◽  
Xrd Analysis ◽  
Antibacterial Activities ◽  
Mice Model ◽  
Ag Nps ◽  
Silver Nanocomposites ◽  
Amorphous Structures

Reaction of 2-mercapto-3-phenylquinazolin-4(3H)-one (MPQ) with both 4-vinyl benzyl chloride and allyl bromide furnished the reactive heterocyclic monomers 3-phenyl-2-((4-vinylbenzyl) thio) quinazolin-4(3H)-one (PVTQ) and 2-(allylthio)-3-phenylquinazolin-4(3H)-one (APQ), respectively. Copolymerization of PVTQ monomer with styrene and methyl methacrylate in the presence of 2,2&prime;-azobisisobutyronitrile (AIBN) afforded the copolymers PS-co-PPVTQ and PMMA-co-PPVTQ, respectively. Similarly, copolymerization of monomer APQ with styrene and methyl methacrylate (MMA) afforded the copolymers PS-co-PAPQ and PMMA-co-PAPQ, respectively. The resulted copolymers were characterized by using FT-IR, 1H-NMR and GPC techniques. Silver nanocomposites of PS, PMMA, PS-co-PPVTQ, PMMA-co-PPVTQ, PS-co-PAPQ and PMMA-co-PAPQ were synthesized by the addition of silver nitrate into the polymer solution. The reduction of silver ions into silver nanoparticles was performed in DMF and water. Thermogravimetric (TGA) analysis was used to determine the thermal stability of the copolymers and their silver nanocomposites. The X-ray diffraction (XRD) analysis indicated the amorphous structures of the co-polymers and confirmed the formation of silver nanoparticles. The antitumor and antibacterial activities were screened for the copolymers and enhanced by the formation of their silver nanocomposites. In vivo antitumor activity in Ehrlich Ascitic Carcinoma (EAC) mice model showed that PS-co-PPVTQ/Ag NPs, PMMA-co-PPVTQ/Ag NPs, and PMMA-co-PAPQ/Ag NPs displayed promising inhibitory effects against EAC and induce apoptosis against MCF-7 cells.

Effect of pH on the Green Synthesis of Silver Nanoparticles through Reduction with Pistiastratiotes L. Extract

2015 ◽  
Vol 1131 ◽  
pp. 223-226 ◽  
Author(s):  
Pranlekha Traiwatcharanon ◽  
Kriengkri Timsorn ◽  
Chatchawal Wongchoosuk
Keyword(s):  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Spherical Shape ◽  
Silver Ions ◽  
Basic Medium ◽  
Metallic Silver ◽  
Visible Spectroscopy ◽  
Ag Nps ◽  
Transmission Electron ◽  
Effects Of Ph

In this work, we have presented the green synthesis of silver nanoparticles (Ag-NPs) using extracts of Pistiastratiotes L. as reducing agent. The silver nitrate (AgNO3) solutions were used as precursor. The experiments were performed under irradiation with a light that can help to increase the activation for reduction of silver ions (Ag+) to metallic silver (Ag0). The effects of pH on the nature of Ag-NPs have been systematically studied by using ultraviolet-visible spectroscopy (UV-Vis) and transmission electron microscopy (TEM). The results show that the synthesis of Ag-NPs in acidic medium gives smaller size than that in basic medium. A number of synthesized Ag-NPs increase with increasing the concentrations of acidic/basic medium. All synthesized Ag-NPs have spherical shape.

scholarly journals Synthesis and Application of Silver Nanoparticles (Ag NPs) for the Prevention of Infection in Healthcare Workers

2019 ◽  
Vol 20 (15) ◽  
pp. 3620 ◽  
Author(s):  
Shingo Nakamura ◽  
Masahiro Sato ◽  
Yoko Sato ◽  
Naoko Ando ◽  
Tomohiro Takayama ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Healthcare Workers ◽  
High Efficiency ◽  
Particle Surface ◽  
Silver Ions ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Medical Field ◽  
Ag Nps ◽  
Environment Friendly

Silver is easily available and is known to have microbicidal effect; moreover, it does not impose any adverse effects on the human body. The microbicidal effect is mainly due to silver ions, which have a wide antibacterial spectrum. Furthermore, the development of multidrug-resistant bacteria, as in the case of antibiotics, is less likely. Silver ions bind to halide ions, such as chloride, and precipitate; therefore, when used directly, their microbicidal activity is shortened. To overcome this issue, silver nanoparticles (Ag NPs) have been recently synthesized and frequently used as microbicidal agents that release silver ions from particle surface. Depending on the specific surface area of the nanoparticles, silver ions are released with high efficiency. In addition to their bactericidal activity, small Ag NPs (<10 nm in diameter) affect viruses although the microbicidal effect of silver mass is weak. Because of their characteristics, Ag NPs are useful countermeasures against infectious diseases, which constitute a major issue in the medical field. Thus, medical tools coated with Ag NPs are being developed. This review outlines the synthesis and utilization of Ag NPs in the medical field, focusing on environment-friendly synthesis and the suppression of infections in healthcare workers (HCWs).

scholarly journals A Facile Method for the Fabrication of Silver Nanoparticles Surface Decorated Polyvinyl Alcohol Electrospun Nanofibers and Controllable Antibacterial Activities

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2486 ◽  
Author(s):  
Yan Yang ◽  
Zhijie Zhang ◽  
Menghui Wan ◽  
Zhihua Wang ◽  
Xueyan Zou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Silver Nanoparticles ◽  
Polyvinyl Alcohol ◽  
Size Distribution ◽  
Antibacterial Properties ◽  
Electrospun Nanofibers ◽  
Antibacterial Activities ◽  
Antimicrobial Activities ◽  
Ag Nps ◽  
Particles Size Distribution

Polyvinyl alcohol (PVA) electrospun nanofibers (NFs) are ideal carriers for loading silver nanoparticles (Ag NPs) serving as antibacterial materials. However, it is still a challenge to adjust the particles size, distribution, and loading density via a convenient and facile method in order to obtain tunable structure and antimicrobial activities. In this study, Ag NPs surface decorated PVA composite nanofibers (Ag/PVA CNFs) were fabricated by the solvothermal method in ethylene glycol, which plays the roles of both reductant and solvent. The morphology and structure of the as-fabricated Ag/PVA CNFs were characterized by scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, X-ray diffraction, UV-visible spectroscopy, and Fourier transform infrared spectroscopy. Ag NPs had an average diameter of 30 nm, the narrowest size distribution and the highest loading density were successfully decorated on the surfaces of PVA NFs, at the AgNO3 concentration of 0.066 mol/L. The antibacterial properties were evaluated by the methods of absorption, turbidity, and growth curves. The as-fabricated Ag/PVA hybrid CNFs exhibit excellent antimicrobial activities with antibacterial rates over 98%, especially for the sample prepared with AgNO3 concentration of 0.066 mol/L. Meanwhile, the antibacterial effects are more significant in the Gram-positive bacteria of Staphylococcus aureus (S. aureus) than the Gram-negative bacteria of Escherichia coli (E. coli), since PVA is more susceptive to S. aureus. In summary, the most important contribution of this paper is the discovery that the particles size, distribution, and loading density of Ag NPs on PVA NFs can be easily controlled by adjusting AgNO3 concentrations, which has a significant impact on the antibacterial activities of Ag/PVA CNFs.

scholarly journals Plant Extract Induced Biogenic Preparation of Silver Nanoparticles and Their Potential as Catalyst for Degradation of Toxic Dyes

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1235
Author(s):  
Khalida Naseem ◽  
Muhammad Zia Ur Rehman ◽  
Awais Ahmad ◽  
Deepak Dubal ◽  
Tahani Saad AlGarni
Keyword(s):  
Silver Nanoparticles ◽  
Catalytic Reduction ◽  
Catalyst Activity ◽  
Citrus Fruit ◽  
Silver Ions ◽  
Order Kinetic ◽  
Citrus Paradisi ◽  
Ag Nps ◽  
Toxic Dyes ◽  
Order Kinetic Model

This study focusses on the synthesis of silver nanoparticles (Ag-nPs) by citrus fruit (Citrus paradisi) peel extract as reductant while using AgNO3 salt as source of silver ions. Successful preparation of biogenic CAg-nPs catalyst was confirmed by turning the colorless reaction mixture to light brown. The appearance of surface Plasmon resonance (SPR) band in UV-Vis spectra further assured the successful fabrication of nPs. Different techniques such as FTIR, TGA and DLS were adopted to characterize the CAg-nPs. CAg-nPs particles were found to excellent catalysts for reduction of Congo red (CR), methylene blue (MB), malachite green (MG), Rhodamine B (RhB) and 4-nitrophenol (4-NP). Reduction of CR was also performed by varying the contents of NaBH4, CR and catalyst to optimize the catalyst activity. The pseudo first order kinetic model was used to explore the value of rate constants for reduction reactions. Results also interpret that the catalytic reduction of dyes followed the Langmuir–Hinshelwood (LH) mechanism. According to the LH mechanism, the CAg-nPs role in catalysis was explained by way of electrons transfer from donor (NaBH4) to acceptor (dyes). Due to reusability and green synthesis of the CAg-nPs catalyst, it can be a promising candidate for the treatment of water sources contaminated with toxic dyes.

scholarly journals Silver nanoparticles: Green Synthesis and Their Antibacterial efficiency

2021 ◽  
Vol 59 (2) ◽  
pp. 214
Author(s):  
Dung Ngo Thanh ◽  
Nguyet Ha Minh ◽  
Tam Le Thi Thanh ◽  
Lu Le Trong
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Green Synthesis ◽  
Silver Nitrate ◽  
Tannic Acid ◽  
Ag Nanoparticles ◽  
Sodium Citrate ◽  
Reducing Agents ◽  
Ag Nps ◽  
Silver Nps

In this study, silver nanoparticles were synthesized from aqueous silver nitrate through a simple and eco-friendly route using a combination of two reducing agents: sodium citrate and tannic acid. By this method, the obtained Ag nanoparticles (NPs) were stable within the studied period of six months. Besides, both TEM images and UV-Vis results showed that the size of silver NPs could be controlled by changing the concentration of tannic acid. The antibacterial ability of Ag NPs with different sizes were also examined. In detail, the smaller the Ag NPs were, the more efficient their antibacterial activity was.

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