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Synthesis of silver nanoparticles by γ-ray irradiation in acetic water solution containing chitosan

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Abstract

Silver nanoparticles were synthesized by gamma-ray irradiation of acetic water solutions containing AgNO3 and chitosan. The resulting particles with the average diameter of 4 5 nm were densely dispersed in the solution due to the protection of chitosan chains. UV vis spectra showed that the irradiation dose would affect the size distribution of nanoparticles.

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... The dark brownish black color of the hydrogel disks indicated the formation of silver nanoparticles within the swollen hydrogel [26]. Silver nanoparticles was tested by UV-Vis spectral analysis in the range of 300-600 nm wavelength that are assigned to silver nanoparticles which arose from the surface plasmon resonance (SPR) [27]. The absorption peaks of silver nanoparticle extracted from P(NVP/Dextran)-Ag nanocomposites at different silver ion concentrations is illustrated in Fig. 5. From the figure it can be showed that, by increasing the concentration of silver nitrate the peak intensities become higher which due to the increase of silver nanoparticles entrapped inside the hydrogel network. ...
... From the figure it is important to notice that by increasing of the silver ion contents in the P(NVP/Dextran), the silver nanoparticles was found to be increased. This increase of the Ag nanoparticles size may be due to the increase of the chance of aggregations to form larger particle size [27]. The formention results obtained by X-ray diffraction are in good agreement with that of the DLS. ...
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The preparation of interpenetrating hydrogel networks (IPN) based on cross-linked poly (N-vinyl pyrrolidone/Dextran) P(NVP/Dex) and poly (N-vinyl pyrrolidone/Dextran)-Ag nanocomposites P(NVP/Dex)-Ag prepared by gamma radiation. Highly stable and uniformly distributed silver nanoparticles have been obtained within hydrogel networks as nanoreactors via in situ reduction of silver nitrate (AgNO3) using sodium borohydride (NaBH4) as reducing agent. The formation of P(NVP/Dex)-Ag has been confirmed by fourier transform infrared (FT-IR) spectroscopy. The ultraviolet visible (UV–vis) spectroscopy measurements show a distinct characteristic absorption peaks around 420 nm indicating the formation of silver nanoparticles. The thermogravimetric analysis (TGA) results confirm the increase in thermal stability by incorporation of silver nanoparticles. X-ray diffraction (XRD) analysis and dynamic light scattering (DLS) results demonstrate that the hydrogels have regulated the silver nanoparticles size to a nanoscale with a range between 9.9–15.1 nm and 47.1–73.7 nm respectivelly. The combination of silver nanoparticles with Doxorubicin (DOX) as a model of antitumor drug forms a new biocompatible nano-drug. Our results show that, the mixing of silver nanoparticles with Doxorubicin can effectively increase the antitumor activity and enhance the cytotoxicity. Graphic Abstract
... Gamma radiation was used to induce the reduction of Ag ? into metallic Ag in different aqueous solutions; acetic water solution containing chitosan (Chen et al. 2007), aqueous silk fibroin (SF) solution (Madhukumar et al. 2017), and poly (N-vinylpyrrolidone) solution (Dhayagude et al. 2018). Also, Bacterial synthesis of AgNPs has gained tremendous significance over chemical methods due to the use of green, biocompatible, and hazard-free reducing and stabilizing agents (Singh et al. 2015;Gudikandula and Maringanti et al. 2016). ...
... Recently, Musino et al. (2021) showed that the hydroxyl groups on the surface of BC act as nucleation points for AgNPs through ion-dipole interaction, and OH groups represent the effective nucleation point for AgNPs synthesis on a BC solid surface. Gamma-ray has been used to induce the reduction process and create primary radicals in many studies (Chen et al. 2007;Park et al. 2012;Van Phu et al. 2014;Madhukumar et al. 2017;Dhayagude et al. 2018). ...
Article
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Antibacterial coatings based on bacterial cellulose (BC) have been widely used in many fields including food packaging and wound dressing. In this study, we aimed to synthesis of colloidal AgNPs and BC/ AgNP composite by using two green, facile methods, the first one by using BC produced by K. rhaeticus N1 MW322708 as a reducing agent in one step reaction induced by gamma-ray. The second approach was achieved by using K. rhaeticus N1 MW322708 cell-free filtrate (CFF) as a reducing agent under the induction action of sunlight. The optical spectra of synthesized AgNPs revealed that the surface Plasmon resonance was localized around 420 and 415 nm for method 1 and method 2, respectively. DLS analysis showed that the Z-Average (nm) of synthesized AgNPs was 42.23 and 36.36 nm for method 1 and method 2 respectively, while the zeta potential was − 27.7 and − 32.7 mV for the first and second method, respectively. TEM images revealed the spherical shape of synthesized AgNPs for two methods. The results of FESEM, FTIR, and XRD confirmed the formation of BC/AgNP composite for two methods. BC/AgNP composite (1 and 2) and AgNPs produced by the two methods, exhibited antibacterial potency against both Gram-positive and Gram-negative bacteria. We concluded that the two green, non-toxic, economical, and novel two methods presented in this paper offer promising routes for both AgNPs and BC/AgNP composite synthesis and have the potential to be applied in the future development of food packing, biomedical instruments, and therapeutics. Graphical abstract
... Numerous approaches like physical, chemical and biological schemes are used for the synthesis of nanoparticles (NPs). Physical methods include laser ablation [10], lithography [11] and high energy irradiation [12]. Chemical approaches include chemical, electrochemical and phytochemical reduction processes [12][13][14]. ...
... Physical methods include laser ablation [10], lithography [11] and high energy irradiation [12]. Chemical approaches include chemical, electrochemical and phytochemical reduction processes [12][13][14]. Chemical methods have the important advantage of being less time-consuming, but these protocols demand the use of toxic chemicals in the synthesis of the NPs, resulting with the formation of non-ecofriendly by-products [15]. ...
Chapter
Nanotechnology is a cutting-edge technology nowadays. Nanoparticles have diversified applications due to their unique properties. Numerous physico-chemical procedures have been developed for the preparation of nanoparticles. Different protocols have different specific limitations. In order to overcome these limitations and in the search for cleaner and less toxic methodologies, biosynthesis of nanoparticles has emerged as an advanced branch of nanotechnology, which has brought out the fascinating role of microorganisms in the green synthesis of nanoparticles. The bacteria and the fungi from both the terrestrial habitat and marine habitat are well-known for their important role in the biosynthesis of nanoparticles. This chapter discusses the role of bacteria and fungi from terrestrial habitat in the synthesis of nanoparticles. Biosynthesized nanoparticles have been investigated by the scientific community for gaining knowledge on their interactions with plants. The plant–nanoparticles interactions is a newly emerged area which calls for more extensive studies as the said interactions may lead to both positive and negative impacts on the plants, with respect to their development, growth and toxicity. Interactions between plants and various biosynthesized nanoparticles have been reviewed in the text.
... In general, the radiolysis process involves producing a large number of homogenously distributed hydrated radicals [21,[30][31][32][33]. Hydrated electrons and primary radicals and molecules appeared when the AgNO3/PL aqueous suspensions were exposed to γrays, as shown in Equation (1). ...
... In general, the radiolysis process involves producing a large number of homogenously distributed hydrated radicals [21,[30][31][32][33]. Hydrated electrons and primary radicals and molecules appeared when the AgNO 3 /PL aqueous suspensions were exposed to γ-rays, as shown in Equation (1). ...
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The production of pure silver nanoparticles (Ag-NPs) with unique properties remains a challenge even today. In the present study, the synthesis of silver nanoparticles (Ag-NPs) from natural pullulan (PL) was carried out using a radiation-induced method. It is known that pullulan is regarded as a microbial polysaccharide, which renders it suitable to act as a reducing and stabilizing agent during the production of Ag-NPs. Pullulan-assisted synthesis under gamma irradiation was successfully developed to obtain Ag-NPs, which was characterized by UV-Vis, XRD, TEM, and Zeta potential analysis. Pullulan was used as a stabilizer and template for the growth of silver nanoparticles, while gamma radiation was modified to be selective to reduce silver ions. The formation of Ag-NPs was confirmed using UV–Vis spectra by showing a surface plasmon resonance (SPR) band in the region of 420–435 nm. As observed by TEM images, it can be said that by increasing the radiation dose, the particle size decreases, resulting in a mean diameter of Ag-NPs ranging from 40.97 to 3.98 nm. The XRD analysis confirmed that silver metal structures with a face-centered cubic (FCC) crystal were present, while TEM images showed a spherical shape with smooth edges. XRD also demonstrated that increasing the dose of gamma radiation increases the crystallinity at a high purity of Ag-NPs. As examined by zeta potential, the synthesized Ag-NP/PL was negatively charged with high stability. Ag-NP/PL was then analysed for antimicrobial activity against Staphylococcus aureus, and it was found that it had high antibacterial activity. It is found that the adoption of radiation doses results in a stable and green reduction process for silver nanoparticles.
... 28 Increased SPR peak intensity corresponds to increased synthesis of Ag NPs, which is in turn due to an increase in the oxidation of hydroxyl groups of chitosan by silver ions. 31 In addition, Chen et al. 24 reported that reduction of silver using γ irradiation can be possible and found that an irradiation dose of 100 kGy was suitable to obtain evenly and densely dispersed silver nanoparticles. Lately, Affes et al. reported that Ag NPs synthesized using low-MW chitosan derivatives exhibited a maximum SPR absorption band with narrow spectra indicating the presence of less polydisperse nanoparticles. ...
... 27 The more the polymer degradation, the more the interaction between Ag and the NH 2 group, and as a result, production of Ag NPs will be more. 24 In the present study, NL-CSN + AgNO 3 showed a yellowish color, indicating that a very small fraction of Ag NPs formed because only the chitosan has a role in the reduction of AgNO 3 ; there was no involvement of hydrated radicals in the absence of γ-irradiation. As the Ag + ions and the ions from chitosan reduced, the ζ potential was observed to be decreased in both of the cases of NL-CSN + AgNO 3 and IR-CSN + AgNO 3 . ...
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Chitosan (CSN) and its derivatives are being exploited for their potential role in agriculture in mitigating environmental stress factors. The present study was aimed to enhance the synthesis of chitosan (CSN)-based silver nanoparticles (Ag NPs) using γ-irradiated chitosan (IR-CSN) and to study the antimicrobial activity of IR-CSN–Ag NPs. The chitosan–silver nanocomposites (CSN–Ag NPs) were prepared by employing the green synthesis method using normal chitosan (high molecular weight (MW), NL-CSN) and oligochitosans (low MW, IR-CSN). The latter was derived by irradiation with γ rays (⁶⁰Co) at 100 kGy dose to obtain a lower MW (approximately 25 kDa). NL-CSN and IR-CSN (0.0–2.5% w/v) were amalgamated with different concentrations of silver nitrate (0.0–2.5% w/v) and vice versa. The UV–visible spectra displayed a single peak in the range of 419–423 nm, which is the characteristic surface plasmon resonance (SPR) for Ag NPs. The physicochemical properties were assessed using different methods such as transmission electron microscopy (TEM), Fourier transform infrared (FTIR), zetasizer, elemental (CHNS) analysis, etc. The degree of Ag NP synthesis was more in IR-CSN than NL-CSN. The in vitro disc diffusion assay with IR-CSN–Ag NPs exhibited a significantly higher antimicrobial activity against Escherichia coli. Further evaluation of the antifungal activity of IR-CSN and Ag NPs showed a synergistic effect against chickpea wilt (Fusarium oxysporum f. sp. ciceris). The study has provided a novel approach for the improved synthesis of CSN–Ag nanoparticle composites using γ-irradiated chitosan. This study also opens up new options for the development and deployment of γ-irradiated chitosan–silver nanocomposites for the control of phytopathogens in sustainable agriculture.
... Gamma radiation was used to induce the reduction of Ag ? into metallic Ag in different aqueous solutions; acetic water solution containing chitosan (Chen et al. 2007), aqueous silk fibroin (SF) solution (Madhukumar et al. 2017), and poly (N-vinylpyrrolidone) solution (Dhayagude et al. 2018). Also, Bacterial synthesis of AgNPs has gained tremendous significance over chemical methods due to the use of green, biocompatible, and hazard-free reducing and stabilizing agents (Singh et al. 2015;Gudikandula and Maringanti et al. 2016). ...
... Recently, Musino et al. (2021) showed that the hydroxyl groups on the surface of BC act as nucleation points for AgNPs through ion-dipole interaction, and OH groups represent the effective nucleation point for AgNPs synthesis on a BC solid surface. Gamma-ray has been used to induce the reduction process and create primary radicals in many studies (Chen et al. 2007;Park et al. 2012;Van Phu et al. 2014;Madhukumar et al. 2017;Dhayagude et al. 2018). ...
Article
Full-text available
Antibacterial coatings based on bacterial cellulose (BC) have been widely used in many fields including food packaging and wound dressing. In this study, we aimed to synthesis of colloidal AgNPs and BC/ AgNP composite by using two green, facile methods, the first one by using BC produced by K. rhaeticus N1 MW322708 as a reducing agent in one step reaction induced by gamma-ray. The second approach was achieved by using K. rhaeticus N1 MW322708 cell-free filtrate (CFF) as a reducing agent under the induction action of sunlight. The optical spectra of synthesized AgNPs revealed that the surface Plasmon resonance was localized around 420 and 415 nm for method 1 and method 2, respectively. DLS analysis showed that the Z-Average (nm) of synthesized AgNPs was 42.23 and 36.36 nm for method 1 and method 2 respectively, while the zeta potential was-27.7 and-32.7 mV for the first and second method, respectively. TEM images revealed the spherical shape of synthesized AgNPs for two methods. The results of FESEM, FTIR, and XRD confirmed the formation of BC/AgNP composite for two methods. BC/AgNP composite (1 and 2) and AgNPs produced by the two methods, exhibited antibacterial potency against both Gram-positive and Gram-negative bacteria. We concluded that the two green, non-toxic, economical, and novel two methods presented in this paper offer promising routes for both AgNPs and BC/AgNP composite synthesis and have the potential to be applied in the future development of food packing, biomedical instruments, and therapeutics.
... The XRD patterns of the chitosan-AgNPs and chitosan-AuNPs are shown in Figure 3. The XRD pattern of the chitosan-AgNPs exhibited a strong characteristic peak for chitosan at about 20 • (Figure 4a), while the XRD showed another peak at about 64 • and 77 • corresponding to Ag nanoparticles in addition to the chitosan at 20 • [23][24][25]. Additionally, the XRD pattern for chitosan-AuNPs showed a characteristic peak at about 20 • , and for gold nanoparticles at 38 • , and 66 • . ...
... Several reports have mentioned that silver nanoparticles have a stronger antimicrobial activity than gold nanoparticles; this may be due to a stronger plasmon resonance in the silver nanoparticle. chitosan at about 20° (Figure 4a), while the XRD showed another peak at about 64° and 77° corresponding to Ag nanoparticles in addition to the chitosan at 20° [23][24][25]. Additionally, the XRD pattern for chitosan-AuNPs showed a characteristic peak at about 20°, and for gold nanoparticles at 38°, and 66°. Figure 4 illustrates the FTIR spectra of chitosan, chitosan-AgNPs, and chitosan-AuNP conjugates synthesized with Aspergillus sp. ...
Article
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Nanotechnology is emerging as a new technology with encouraging innovations. Global antibiotic use has grown enormously, with antibiotic resistance increasing by about 80 percent. In view of this alarming situation, intensive research has been carried out into biogenic nanoparticles and their antibacterial, antifungal, and antitumor activities. Many methods are available to enhance stability and dispersion via peroration of conjugate with a polymer, such as chitosan, and other bioactive natural products. Two marine fungi were isolated and identified as Aspergillus sp. and Alternaria sp. via sequencing of the 16S rRNA gene. In this work, these strains were used to form the conjugation of biogenic silver nanoparticles (AgNPs) from Aspergillus sp. Silv2 extract and gold nanoparticles (AuNPs) from Alternaria sp. Gol2 extracts with chitosan to prepare chitosan–AgNPs and chitosan–AuNP conjugates. A variety of imaging and analytical methods, such as UV–vis, X-ray powder diffraction (XRD), FTIR spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were utilized to characterize biogenic nanoparticles and conjugates. The biosynthesized Ag and Au nanoparticles along with the prepared conjugates were evaluated for their antimicrobial effects on Gram-negative and Gram-positive bacterial isolates, including Escherichia coli and Staphylococcus aureus. Both chitosan–AgNP and AuNP showed powerful antimicrobial activities compared to the control. On the other hand, chitosan–AgNP conjugation had better antibacterial ctivity than chitosan–AuNPs, which exhibited moderate activity against S. aureus and very low activity against E. coli. Furthermore, the antibiofilm potentials of the prepared conjugates were tested against four biofilm-forming bacteria, including P. aeruginosa, B. subtilis, E. coli, and S. aureus. The obtained results indicate that the chitosan–AgNP showed a promising anti-biofilm activities on all strains, especially S. aureus, while chitosan–AuNP conjugates showed moderate anti-biofilm against B. subtilis and weak activities against the other three strains. These results showed the superiority of chitosan–AgNP as a promising antibacterial as well as biofilm formation inhibitors.
... Further, Sanpui et al. [50] observed the surface plasmon resonance (SPR) peak of Cs-AgNPs at 410 nm, whereas Murugan et al. [51] reported the confirmation peak for Cs-AgNPs at 441 nm. In addition, Chen et al. [52] studied the UV absorption pattern against various dose of γ-ray irradiation on chitosan nanoparticles. They reported that a single narrow peak is produced at low irradiation dose (27 kGy) thereby indicating narrow size distribution pattern of chitosan nanoparticles. ...
Article
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: Mosquito-borne diseases are causing serious damage to public health worldwide, and control of these deadly mosquito vectors is a major thrust area for epidemiologists and public health workers. Therefore, the present research reports an eco-friendly solution with multipotency of silver nanoparticle fabricated from shrimp shell biowaste in controlling mosquitoes and bacterial pathogens. The biofabricated chitosan silver nanoparticles (CsAgNPs) were confirmed by UV-visible spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction and zeta potential analysis. The TEM studies showed that the obtained Cs-AgNPs were mostly spherical in shape. Low doses of chitosan and Cs-AgNPs showed high mosquitocidal properties against both larvae and adult of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The LC50 (lethal concentration 50%) of CsAgNPs was 10.240 ppm (fourth instar larvae) and 9.671 ppm (adult) for An. stephensi; 11.349 ppm (fourth instar) and 12.015 ppm (adult) for Ae. aegypti and 12.426 ppm (fourth instar) and 12.965 ppm (adult) for Cx. quinquefasciatus. The concerning part of antibacterial studies showed that CsAgNP had significant inhibition on tested bacterial pathogens. Overall, this study shows that chitosan extracted from the shrimp shell wastes can be used as a potential source for controlling major mosquito vectors.
... Ionizing radiation can also reduce silver ions for AgNPs preparation. Different ionized irradiation such as γ and UV irradiations have been used for AgNPs synthesis (Mafuné et (Chen et al., 2007) have also been used. Synthesis procedures using microwave irradiation has also been employed using glutathione (Kharissova et al., 2013) and a combination of culture supernatanant of Bacillus subtilis (Saifuddin et al., 2009). ...
... Additionally, past research has been focused on the fine manipulation of the crystallinity, shape, size, and stability of AgNPs to achieve various physicochemical characteristics. Although green biological synthesis methods at present are mostly preferred over chemical and physical techniques (e.g., photochemical, electrochemical, thermal, radiation, lithographic, and laser ablation processes) to tailor nanoparticle qualities toward specific applications, any inevitable use of hazardous materials during the synthesis or structuring of AgNPs should not be overlooked in terms of usage and environmental safety [167][168][169][170]. Other gaps in AgNP research should also be pinpointed to attain more comprehensive insight in this field. ...
Article
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Nanobiotechnology has undoubtedly influenced major breakthroughs in medical sciences. Application of nanosized materials has made it possible for researchers to investigate a broad spectrum of treatments for diseases with minimally invasive procedures. Silver nanoparticles (AgNPs) have been a subject of investigation for numerous applications in agriculture, water treatment, biosensors, textiles, and the food industry as well as in the medical field, mainly due to their antimicrobial properties and nanoparticle nature. In general, AgNPs are known for their superior physical, chemical, and biological properties. The properties of AgNPs differ based on their methods of synthesis and to date, the biological method has been preferred because it is rapid, nontoxic, and can produce well-defined size and morphology under optimized conditions. Nevertheless, the common issue concerning biological or biobased production is its sustainability. Researchers have employed various strategies in addressing this shortcoming, such as recently testing agricultural biowastes such as fruit peels for the synthesis of AgNPs. The use of biowastes is definitely cost-effective and eco-friendly; moreover, it has been reported that the reduction process is simple and rapid with reasonably high yield. This review aims to address the developments in using fruit- and vegetable-based biowastes for biologically producing AgNPs to be applied as antimicrobial coatings in biomedical applications.
... The silver nitrate dosimeter features a linear response and good measurements reproducibility [10]. The influence of γ-rays on silver nitrate was examined [6,[16][17][18][19][20]. It is actually suggested as a liquid detector based on precursors of Ag nanoparticles and 1% sodium citrate, where the ionizing radiation induces the formation of spherical AgNPs, recognized by the appearance of a sharp peak around 410 nm in the absorbance spectrum of the colloidal solution [21]. ...
Article
Radiation-induced Ag° nanoparticles (NPs) in silver nitrate gel dosimeter incorporating various components was investigated in the dose range of 0–100 Gy. The gel responses were analyzed at 450 nm, a Surface Plasmon Resonance band of AgNPs. The radiation sensitivity of the gel increases with increasing Ag+ concentrations and isopropanol, % and decreases with boosting gelatin content and H+ ions. This gel features good water equivalency in energies from 0.3 to 20 MeV and has potential applications in the dose range of 5–100 Gy based on the selected compositions. Thus, it can cover blood irradiation and radiotherapy dosimetry applications.
... Among these nanomaterials silver nanoparticles (AgNPs) with unique properties of high antimicrobial activity have attracted much interest from scientists and technologies to develop nanosilver based disinfectant products [5,6]. AgNPs have been synthesized by physiochemical techniques such as chemical reduction [7], gamma ray radiation [8], micro emulsion [9], electrochemical method [10], laser ablation [11], autoclave [12], microwave [13] and photochemical reduction [14]. These methods have effective yield but they are associated with some limitations like use of toxic chemicals and high operational cost and energy needs [15,16]. ...
Article
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Silver nano particles (AgNPs) were green synthesized using Adansonia digitata leaf extract. The synthesized silver nano particles were characterized in terms of synthesis, size, shape, morphology and capping functionalities by UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Antimicrobial activity of the synthesized silver nano particles was investigated by well diffusion method. The antibacterial activity of the nano particle was studied against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pseudomonas aeurigunosa, Salmonella typhi and Klebsiella pneumonae while the antifungal activity was studied against Candida albicans, Aspergillus niger, Penicillum notatum and Rhizopus stolomifer. The synthesized AgNPs was active against all the studied microorganisms. Staphylococcus aureus was the most susceptible bacterium (inhibition zones ranging from 12.00 to 28.00 mm, MIC: 30 µl, MBC: 50 µl) while Aspergillus niger was the most susceptible fungi (inhibition zones ranging from 10.00 to 18.00 mm, MIC: 90 µl, MFC: 120 µl. In conclusion the synthesized silver nanoparticles was found to have antimicrobial activity against the pathogenic bacteria and fungi tested and hence has a great potential in biomedical application for the treatment of microbial infections.
... Synthesis of nanoparticles using phytochemicals is most trending in the present scenario due to their unique properties. Nanoparticles can be synthesized using the various physiochemical methods like gamma-ray irradiation 6 , micro-emulsion 31 , microwave irradiation 16 , laser ablation 1 , electrochemical reduction 22 , autoclaving 30 , chemical reduction 15 and photochemical reduction 3 . Among these, green synthesis is a better technique for synthesizing the nanoparticles because it is cost-effective and environmentfriendly 5 . ...
Article
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This study reports an investigation of the microwave-assisted synthesis of silver nanoparticles (AgNPs) using an extract of Ficus racemosa leaves. The formation of AgNPs was established by various techniques such as UV-Visible Spectroscopy (UV-Vis) analysis, Scanning electron microscopy (SEM) for shape and size analysis and Fourier Transformed Infrared spectroscopy (FTIR) for phytochemical analysis involved in reduction of silver ions. Further antibacterial activity was tested against P. aeruginosa, B. cereus, C. jejuni, B. subtilis, L. Monocytogenes, and C. perfringenes. The results indicated the rapid formation of AgNPs during microwave irradiation with improved properties to those obtained by the heating method. The use of microwaves resulted in the smaller size of particles approximately 30 to 60nm. Prepared nanoparticles demonstrated antibacterial property against some bacterial strain and dye degradation.
... was, the weaker the AgNPs adsorption peak (at ~ 400 nm) was. This result could be explained that at high doses of γ-irradiation, PEG molecules were degraded and lost the protective effect on silver nanoparticles, caused them to aggregate and form larger particles, with different UV-Vis adsorption properties. Similar trend was observed in the study of Chen et. al. (2007). The signal of TNTs at ~ 270 nm became stronger as the irradiation dose augmented, due to the higher crystallization of TiO 2 nanotubes under γ-ray exposure. Together with obtained FTIR spectra, these results indicated that GO, AgNPs and TNTs actually interacted with each other to form the nanocomposite products under γ-ray irradiation. ...
Article
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In this study, graphene oxide (GO)-TiO2 nanotubes (TNTs)-silver nanoparticles (AgNPs) nanocomposites were synthesized under γ-ray irradiation at different doses (5, 10, 15, 20 and 25 kGy) from formerly synthesized GO, TNTs and AgNPs. They were then characterized by Fourier-transformed infrared (FTIR) and ultra-violet-visible (UV-Vis) spectroscopies, as well as by scanning electron (SEM) and transmission electron (TEM) microscopes. The spectral data indicated the assemblage of silver nanoparticles on both GO sheets and TiO2 nanotubes, as well as the assemblage of TiO2 nanotubes on GO sheets. In addition, their antibacterial activity against Escherichia coli and post-harvest preservation were investigated. Fresh bunches of green grapes were used for this study. AATCC 100-2012 and ISO 21527-1:2008 standards were used for all experiments. The obtained results indicated that all nanocomposite samples exhibited very high antibacterial activity against E. coli. Among which, the 20 kGy sample showed the highest value. Moreover, two samples (5 kGy and 25 kGy) possessed the lower number of yeasts and molds than that of control sample, indicating that the nanocomposites had partial contribution to the preservation of post-harvest crops. We have also found in this study that the dose range affected the antibacterial activity and preservation; and the highest dose range, however, was not always ideal for that purpose. With such fascinating properties, GO-TNTs-AgNPs will be the promising material for antibacterial and agricultural applications.
... The neutral atom Ag 0 reacts with Ag + to form quite stabilized Ag clusters. Finally, such clusters arrange together or absorb neutral Ag 0 in order to form the Ag NPs (Van Phu et al. 2014;Chen et al. 2007). ...
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Practically, 12% of used dyes are excluded as waste in the mobile aqueous environment. Methyl orange (MO), an industrial azo dye, is known to be carcinogenic. Accordingly, this work was engaged to fabrication of a high-efficiency visible light photocatalysts based on Ag-Alginate/Chitosan-coated MgO nanocomposite beads. MgO and Ag were prepared via precipitation and γ-radiation reduction technique as a green physical one, respectively. The degradation mechanisms depended on catalytic reduction by means of sodium borohydride/Ag and photooxidative degradation. XRD proved the periclase crystalline form of MgO of size 20 nm and the formation of face-centered cubic silver crystals of size 15 nm. The degradation yield varied directly with time, MgO, and dye concentration until certain limit. Five and twenty minutes were enough to get clear solution of MO (30 and 15 ppm, respectively) while 60 min was required to achieve the same target for 60 ppm MO solution. The catalysts showed high efficiency for MO of high concentration. The incorporation of Ag into catalytic beads could support both mechanisms as it could elevate the degradation efficiency up to 50% and save the time to a great extent. Thus, this carrier fruitfully converted wastewater into an effluent that can be repaid to the water cycle with minimal strike on the ecosystem. Graphical abstract
... Nanoparticle agglomeration of radiochemically synthesized nanoparticles is avoided by different socalled stabilizing agents, such as polyvinyl alcohol (PVA) [13,16,18], polyvinylpyrrolidone (PVP) [11], gelatine [19], chitosan [20,21], a.s.o. These polymers can create fine coatings onto the particles resulting in a repulsive sterical force which keeps the nanoparticles away from each other -sterical stabilization [22,23]. ...
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Composites of Silver nanoparticles/chitosan were obtained in aqueous solution, in-one step and eco-friendly synthesis, under ambiental conditions, using gamma irradiation. The radiochemical synthesis enabled obtaining of controlled size, monodisperse and high stability Silver nanoparticles. The obtained composites presented UV-Vis surface plasmon resonance comprised between 406-414 nm, depending on composition of the reactant system, spherical shape and narrow particle size distributions, with mean dimensions between 3-55 nm, and good antibacterial properties proven against Staphylococcus aureus and Escherichia coli. The influence of the Silver ions/chitosan ratio and of the pH of the initial solution on the final Ag Np properties is also discussed.
... Due to this change, silver nanoparticles became easier to aggregate and changed their UV-Vis adsorption property. Similar trend was observed in the study of Chen et al. (2007). The signal of TNTs at ~270 nm became stronger as the irradiation dose increased, because of the higher crystallization of TNTs under γ-ray exposure. ...
Article
In this study, graphene oxide (GO) sheets were assembled with silver nanoparticles (AgNPs) and then combined with TiO2 nanotubes (TNTs) by γ-ray irradiation at different doses (5, 10, 15, 20, and 25 kGy), to form GO–AgNPs–TNTs nanocomposites. Their physical and chemical properties were investigated using Fourier-transformed infrared, ultraviolet–visible (UV–Vis) adsorption, Raman and X-ray diffraction (XRD) spectroscopies. Field emission scanning electron and transmission electron (TEM) microscopies were applied for their morphology and structure observation. The obtained results indicated successful assemblage of silver nanoparticles on both GO sheets and TNTs, as well as significant effects of irradiation dose on nanocomposites’ characteristics. Photocatalytic activity of the material was determined by the photodegradation efficiency on rhodamine B dye solution. All nanocomposite samples were revealed to possess good photocatalytic activity, with the highest obtained decoloration efficiency value of 81.21%. Noticeably, the photocatalytic activity of all nanocomposite samples was higher than that of their sole components. With all obtained results, γ-ray irradiation was demonstrated to be a good technique for the synthesis of nanocomposite materials and GO–AgNPs–TNTs nanocomposite proclaimed high potential for pollutants removal and wastewater purification.
... As shown in the gure, diffraction peaks appeared at positions of 10.8°, 25.9°, 31.8°, 32.2°, 32.9°, 39.8°, 46.7°, 49.4°, 53.1°, and 64.1°, which were consistent with characteristic diffraction peaks of hydroxyapatite standards proving the successful preparation of hydroxyapatite.Figure 2brevealed that the XRD pattern of pure CS powder showed characteristic diffraction peaks at only 10.7° and 20° at 2Θ[44,45].From Fig. 2b, the characteristic diffraction peaks of CS and n-HA appeared in the spectrum of CS/n-HA composite microspheres, and the intensity of the characteristic diffraction peak of CS uplift was weakened which were ascribed to the Schiff base reaction reducing the crystallinity of CS during cross-linking[46]. Comparing the diffraction peaks of n-HA (a), the peak shape of the characteristic diffraction peak of n-HA was still obvious in the XRD pattern of CS/n-HA composite microspheres (eg 2Θ = 25.9°, ...
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In this paper, chitosan/hydroxyapatite (CS/n-HA) were synthesized by ultrasound-assisted precipitation combined with inverse crosslinking-emulsion method. In order to obtain a scaffold material with excellent properties, Calcium sulfate hemihydrate (CSH) were combined with CS-HA obtained CSH/CS/n-HA composite scaffold via setting citric acid as solidifying liquid, which possessed better biodegradability, bioactivity, mechanical properties. The physicochemical, morphological properties of scaffolds were characterized by FTIR, XRD and TFSEM. In addition, explored were the mechanical, degradable, biocompatibility and iron release properties. The mechanical strength study indicated that the compressive strength of the porous composite scaffold was influenced by adding an appropriate amount of CS/n-HA composite microspheres. It was proved that the composite scaffold with 6% CS/n-HA content obtained the highest mechanical strength (17.46±1.29 MPa). The results illustrated that the composite scaffold possessed biodegradability and can form hydroxyapatite by dynamic balance of Ca and P elements. The hemolysis tests demonstrate that materials are non-hemolytic and have good blood compatibility. Therefore, the developed composite scaffolds are safe medical inorganic materials, which can potentially be applied in bone tissue engineering.
... The resulting image is an amorphous structure. However, it is seen in the literature that the severe broad peak between 20 and 30 thetas is attributed to chitosan (Chen et al., 2007;Akmaz et al., 2013). Additionally, the peaks of AgN are unfortunately not visible. ...
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Diabetes-related wounds are a significant problem with serious consequences for both patients and health care systems. The aim of this study is to produce healing films that will expedite the healing of diabetic wounds in order to minimize the negative effects experienced by diabetic patients. For this purpose, films were produced by combining chitosan, which possesses the ability to accelerate wound healing, silver nanoparticles, well-known for their superior properties such as preventing the occurrence of microbiological activity and providing thermal stability, and ascorbic acid, also referred to as vitamin C, which the body requires during the treatment process. The films were evaluated by applying a series of characterization analyzes (XRD, FTIR, Transmission Electron Microscopy, DSC-TGA) to the produced films. In addition, the films were subjected to microbiological tests. Following that, the films’ swelling and ascorbic acid release behaviors were investigated in deionized water and a phosphate buffered saline solution with pH 7.4, respectively.
... There are various method includes chemical reduction, gamma ray radiation, microwave assistant vapour deposition, thermal reduction [4,5,6] Wide range of methods including physical, chemical and biological methods have been used for the fabrication of NPs. Physical and chemical methods are popular because they have generated large number of NPs within short time [7][8] Recently nature`s most elegant creators living organism and their parts are used for the synthesis of NPs. ...
Article
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Plants are enormous, easily available natural sources of biomolecules for the synthesis of nanoparticles. Until now about 2000 plants are used for the green synthesis of Nanoparticles. The secondary metabolites present in the plant are a source of capping and stabilizing agents more than 100 different biological sources for synthesizing Silver Nanoparticles are reported till date. It is found out by various reports that the reaction condition and the physiological condition of plant extract are the major factors for the synthesis of Silver Nanoparticles. The other physical factors which affect the size, shape, of Silver Nanoparticles include temperature, stirring the reaction mixture, the concentration of plant extract, and ph of the plant extract. In this review article various aspects of Nanobiotechnology, the reaction of Nanoparticles synthesis, applications of Silver Nanoparticles are summarized and it is critically reviewed.
... Recently gamma radiation gains more attention in AgNPs synthesis. Gamma radiation was used to induces the reduction of Ag + into metallic Ag in different aqueous solutions; acetic water solution containing chitosan (Chen et al., 2007), aqueous silk broin (SF) solution (Madhukumar et al., 2017), and poly (N-vinylpyrrolidone) solution (Dhayagude et al., 2018). The main objective of this work is to synthesis of colloidal AgNPs and BC /AgNP composite by green, eco-friendly, free of toxic approach, characterization, and evolution of the antibacterial activity against some pathogenic bacteria. ...
Preprint
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Antibacterial coatings based on bacterial cellulose (BC) have been widely used in many fields including food packaging and wound dressing. In this study, we aimed to synthesis of colloidal AgNPs and BC/ AgNP composite by using BC as a reducing and capping agent in one step reaction induced by gamma-ray. Bacterial strain Komagataeibacter rhaeticus N1 MW322708 was used for biosynthesis BC by inoculation on Hestrin and Schramm medium and incubated statically at 35 °C for 10 days. BC sheet was formed, harvested, purified, and dried, then used for the synthesis of AgNPs and BC/AgNP by soaked 0.05 g of dried BC in 10ml of 1mM aqueous AgNO 3 solution for 2h and then irradiated by gamma-ray under different doses. Color change from yellow to deep brown indicated the synthesis of AgNPs and BC/AgNP. The optical spectra of synthesized AgNPs revealed that the surface plasmon resonance was localized around 420 nm. DLS analysis showed that the mean diameter of AgNPs was 49.5 nm with a -19.36-mV value of zeta potential. TEM images revealed the spherical shape of synthesized AgNPs. The results of FESEM, FTIR, and XRD confirmed the formation of BC/AgNO 3 composite. The highly crystalline nature of the BC membrane and BC/AgNP composite was observed in XRD measurements with a crystal size of 5.416 and 5.409 nm, respectively. The antibacterial activity of BC and BC/AgNP against pathogenic bacterial isolated from Pastirma food samples revealed that BC does not show antibacterial activity, while BC/AgNP composite showed antibacterial potency against Staphylococcus aureus, Enterococcus faecalis, Listeria monocytogenes, Proteus mirabilis, and Escherichia coli , with an inhibition zone of (mm) 9±1, 9±0.57, 10±1.15, 8±0.5 and 7±0.28, respectively. We concluded that this novel method presented in this paper offers a promising route for both AgNPs and BC/AgNP composites synthesis using a green, renewable biopolymer as a multifunctional agent and potential to be applied in the future development of food packing, biomedical instruments, and therapeutics.
... Moreover, the first review dedicated to antimicrobial CS/AgNPs nanocomposites was publishes in 2015 [126]. The facile method of in situ synthesis in acetic water solution by both chemical [127] and Y-radiation [1,128] resulted in long-lived CS-stabilized AgNPs with sizes less than 6 nm, and antibacterial tests observed a decrease in colonies for E. coli and Bacillus. Swelling capacity of polymer matrix has a great importance on overall antimicrobial performance, as it was shown in several studies [87,129]. ...
Article
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The emerging problem of the antibiotic resistance development and the consequences that the health, food and other sectors face stimulate researchers to find safe and effective alternative methods to fight antimicrobial resistance (AMR) and biofilm formation. One of the most promising and efficient groups of materials known for robust antimicrobial performance is noble metal nanoparticles. Notably, silver nanoparticles (AgNPs) have been already widely investigated and applied as antimicrobial agents. However, it has been proposed to create synergistic composites, because pathogens can find their way to develop resistance against metal nanophases; therefore, it could be important to strengthen and secure their antipathogen potency. These complex materials are comprised of individual components with intrinsic antimicrobial action against a wide range of pathogens. One part consists of inorganic AgNPs, and the other, of active organic molecules with pronounced germicidal effects: both phases complement each other, and the effect might just be the sum of the individual effects, or it can be reinforced by the simultaneous application. Many organic molecules have been proposed as potential candidates and successfully united with inorganic counterparts: polysaccharides, with chitosan being the most used component; phenols and organic acids; and peptides and other agents of animal and synthetic origin. In this review, we overview the available literature and critically discuss the findings, including the mechanisms of action, efficacy and application of the silver-based synergistic antimicrobial composites. Hence, we provide a structured summary of the current state of the research direction and give an opinion on perspectives on the development of hybrid Ag-based nanoantimicrobials (NAMs).
... Since the synthesis of nanoparticles are carried out using various approaches like gamma-ray radiations, use of microemulsions, autoclaving, electrochemical methods, laser ablation, chemical reduction, photochemical reductions, hydrothermal, coprecipitation solvothermal and sonochemical [214][215][216][217][218][219]. These approaches have a low yield and bearing limitations such as high functional cost, use of toxic chemicals and high energy supplies. ...
Article
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Currently green synthesis of nanoparticles has attained much interest because of their safe nature, environmentally benign, ease in manufacturing, and low production cost. It is a reliable process for developing a wide array of nanostructures such as metal salts from plants/fungal/bacterial extract and hybrid materials. Green synthesis of nanoparticles provided promising and sustainable alternative approach to conventional synthesis approaches. Recent studies demonstrated that nanoparticles are highly promising for antiviral and antimicrobial properties. Here in, the advancement in green synthesis of nanoparticles using natural compounds such as plant extracts, fruit juices and other relevant sources have been highlighted. A deep insight into antiviral and antimicrobial activities of these nanoparticles provided. These nanoparticles offer diverse opportunity to counter life threating viral and other antimicrobial infections. This review offers understanding of the recent data that provide the readers various strategies to design and develop advance nanomaterials via greener approach. Current challenges, critical overview and future outlook of the green synthesis of nanoparticles and possibilities of their effective and exotic exploration for antimicrobial and antiviral applications are summarized.
... Since the synthesis of nanoparticles are carried out using various approaches like gamma-ray radiations, use of microemulsions, autoclaving, electrochemical methods, laser ablation, chemical reduction, photochemical reductions, hydrothermal, coprecipitation solvothermal and sonochemical [214][215][216][217][218][219]. These approaches have a low yield and bearing limitations such as high functional cost, use of toxic chemicals and high energy supplies. ...
Article
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In this review, we summarised the different methods for copper nanoparticle synthesis, including green methods. We highlighted that the synthesis of the copper nanoparticles from green sources is preferable as they serve as stable and reducing entities. Furthermore, we critically reviewed the effectiveness of copper-based nanoparticles in oncogenic treatments emphasizing breast, lung, colorectal, and skin cancers. Finally, we have summarised the recent progress made in copper-based nanoparticles and their applications to amplify and rectify present cancer treatment options. The synthesis, characterization, stabilization, and functionalization techniques of various copper-based nanoparticles have also been highlighted in each section. In conclusion, the review provides the outlook of copper nanoparticles in cancer diagnostics and therapeutics.
... The UV-visible (UV-vis) spectra of the resultant AuNP colloidal solutions diluted to 0.1 mM, calculated as the [Au 3+ ] concentration using deionized water, were determined on a UV-Vis spectrophotometer (model UV-2401PC, Shimazu, Japan) [14,25,26]. ...
Article
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Gold nanoparticles capped by carboxymethyl chitosan (AuNPs/CM-chitosan) with particle sizes of 5.2–7.3 nm were successfully synthesized by the γ-irradiation of Au3+ solutions. Their characteristics were analysed by transmission electron microscope images, powder X-ray diffraction patterns, UV-visible spectroscopy, and Fourier transform infrared spectra. The antioxidant activity of AuNP/CM-chitosan was time dependent and much higher than that of ascorbic acid at the same concentration. On the other hand, the results of tail vein injection of AuNP/CM-chitosan in mice indicated that this product was not toxic to mice and that AuNPs were mainly distributed in liver tissue, at approximately 77.5%, 6 h after injection. The hepatoprotective activity of AuNP/CM-chitosan was also tested in acetaminophen-induced hepatotoxic mice by oral administration at daily doses of 0.5–2 mg/head. The results indicated that compared to the control, supplementation with 2 mg of AuNPs/head strongly reduced the aspartate aminotransferase and alanine aminotransferase indexes in the blood of the tested mice by approximately 66.5 and 69.3%, respectively. Furthermore, the MTT (3[4,5 dimetylthiazol-2-yl]-2,5-diphenyltetrazol bromide) assay on a liver cancer cell line (HepG2) clearly confirmed strong anticancer activity on HepG2 cells treated with 0.05–0.5 mM AuNPs and the tested cells did not survive after treatment with 0.5 mM AuNPs, while the growth of the normal cell line (L929) has no significant effect at the same treated concentration of AuNPs. The AuNP/CM-chitosan in the present study was synthesized by the γ-irradiation method without using any toxic-reducing chemical and stabilized in a natural biocompatible polymer. The strong antioxidant, hepatoprotective, and anticancer effects of this product may be supported to be used in the biomedical field.
... Ag np were employed successfully in various devices like opto-eletronic devices [1] due to their high conductivity and well known for their antibacterial [2], anti-microbial and anti-fungal properties [3]. Synthesis of Ag np have been in practice since long time from past to present, utilizing physical [4]and chemical processes [5]. However, these conventional methods of synthesizing nanoparticles known for effective yield, has some limitations such as use of some highly toxic chemicals, high energy requirements and high production cost. ...
Conference Paper
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In the present study, Ag nanoparticles were synthesized by using leaves extract of plant Melia azedarach. Green method was followed in the synthesis of Ag nanoparticles. By this method, Ag nanoparticles have been synthesized in the size range 19 nm-28 nm with maximum absorbance at 325 nm of wavelength. The prepared Ag nanoparticles were found to exhibit fcc structure. Morphological study of the Ag nanoparticles was carried out through FESEM and TEM. FTIR and XPS investigations of prepared nanoparticles revealed the presence of plant components in the prepared nanoparticles and the chemical state of elements present in the synthesized nanoparticles, respectively. Antibacterial activity of Ag nanoparticles was also investigated against pathogens, Escherichia coli and Staphylococcus aureus.
... 1480 Additionally, different chemical methods have been proposed for the synthesis of nanoparticles. They include microemulsion (Richard et al., 2017), microwave wave synthesis (Seku et al., 2018), template methods (Liu et al., 2013), chemical regeneration methods (Kataria, and Garg, 2018), electrochemical reduction (Virginia Roldán et al., 2013), irradiation reduction (Chen et al., 2007), chemical reduction in aqueous solutions (Leopold and Lendl, 2003) and biochemical methods (Ashraf Sabri et al., 2016). ...
Article
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Among metal nanoparticles, silver due to its high electrical and thermal conductivity and being profoundly anti-bacterial and inexpensive has more importance in comparison with other metals such as gold and platinum. Many acidophilic bacteria can be effective in regenerating many of the nanoparticles due to their metabolism. Experimental samples were collected from Faraman Dairy Factory in Rasht industrial town in May 2019. After isolation and molecular identification to investigate the possibility of biosynthesis of silver nanoparticles, isolates were cultured in liquid medium including Nutrient Broth (NB), Luria-Bertani (LB) and De Man, Rogosa and Sharpe (MRS) to compare their yield. After incubation time for 24 hours, the silver nitrate salt was added separately to supernatant and material that dissolves in liquid. Characteristics of silver nanoparticles determined using Transmission Electron Microscopy, XRD and ultraviolet spectrophotometer (UV-Vis) were investigated. The results gained from the study displayed that the isolated Acetobacter and Pediococcus bacterial strain could produce silver nanoparticles in LB medium. It was also found that the Acetobacter and Pediococcus bacteria could not produce silver nanoparticles in NB and MRS culture media. The study showed that the Acetobacter bacteria in the supernatant phase and the precipitate phase of LB culture medium could produce silver nanoparticles. It was also found that the Acetobacter bacteria could produce silver nanoparticles with sizes of 50 nm and 30 nm. Also, the study showed that the Pediococcus bacteria just in the supernatant phase of LB culture medium could produce silver nanoparticles. It was also found that the Pediococcus bacteria could produce silver nanoparticles with sizes of 100 nm and 50 nm.
... The silver nitrate dosimeter features a linear response and good measurements reproducibility [22]. The influence of γ-rays on AgNO 3 solution had been examined [29][30][31][32][33][34]. A liquid detector based on silver nitrate and 1% sodium citrate is introduced, where the ionizing radiation induces the formation of spherical AgNPs as recognized by the appearance of a sharp peak around 410 nm in the absorbance spectrum of the colloidal solution [35]. ...
Article
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The dosimetric characteristics of hydrogel dosimeters based on polyacrylamide (PAC) as a capping agent incorporating silver nitrate as a radiation-sensitive material are investigated using UV-Vis spectrophotometry within the dose range 0–100 Gy. Glycerol was used in the hydrogel matrix to promote the dosimetric response and increase the radiation sensitivity. Upon exposing the PAC hydrogel to γ-ray, it exhibits a Surface Plasmon Resonance (SPR) band at 453 nm, and its intensity increases linearly with absorbed doses up to 100 Gy. The results are compared with the silver nitrate gel dosimeter. Glycerol of 15% in the hydrogel matrix enhances the radiation sensitivity by about 30%. PAC hydrogel dosimeter can be considered a near water equivalent material in the 400 keV–20 MeV photon energy range. At doses less than 15 Gy, the PAC hydrogel dosimeter retains higher radiation sensitivity than the gel dosimeter. The total uncertainty (2σ) of the dose estimated using this hydrogel is about 4%. These results may support the validity of using this hydrogel as a dosimeter to verify radiotherapy techniques and dose monitoring during blood irradiation.
... Vật liệu nano bạc (AgNPs) có nhiều đặc điểm nổi bật đã khiến chúng được ứng dụng rộng rãi trong các lĩnh vực khác nhau như: y sinh [2], dẫn thuốc [3], xử lý nước [4], nông nghiệp [5]… AgNPs cũng được áp dụng trong mực in, chất kết dính, thiết bị điện tử, bột nhão… do độ dẫn cao [6]. AgNPs thường được tổng hợp bằng các kỹ thuật hóa lý như: khử hóa học [7], bức xạ tia gamma [8], vi nhũ tương [9], điện hóa [10], laser [11], thủy nhiệt [12], ...
Article
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Trong nghiên cứu này, vật liệu nano bạc (AgNPs) được tổng hợp bằng phương pháp khử hóa học với chất khử là natri citrate và chất bảo vệ là alginate. Các thông số ảnh hưởng tới quá trình tổng hợp nano bạc gồm nồng độ natri citrate, nồng độ bạc nitrate, nồng độ alginate và nhiệt độ của hệ phản ứng đã được nghiên cứu. Sự hình thành AgNPs, hình thái và cấu trúc của vật liệu sau khi tổng hợp được phân tích bằng quang phổ hấp thụ phân tử, hiển vi điện tử quét, hiển vi điện tử truyền qua và nhiễu xạ tia X. AgNPs có hiệu lực ức chế cao đối với nấm Pyricularia oryzae gây bệnh đạo ôn trên cây lúa.
... Zinc nanoparticles have wide application; various synthetic methods have been employed to produce ZnNps [6] . Zinc nanoparticles can produced from zinc oxide and zinc sulphate. ...
Article
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Soil borne diseases which are caused to various plants include a wide variety of soil microbes like fungi and bacteria, among which Fusarium wilt is one such disease caused by Fusarium oxysporum cubense in banana plants. Wilt disease or the panama disease of plant is among the most destructive disease of banana in the tropics and even the control methods like field sanitation, soil treatments and crop rotations have not been a long term control for this disease. An alternative method of treating Fusarium oxysporum was adopted by using various natural plant leaves of Glycosmis pentaphylla and Azadirachta indica. Nanoparticles are small particles with a dimension of 10-9 and 10-10. Green synthesis is a new method developed for the synthesis of nanoparticles which is small in size, large surface area and eco- friendly. Leaf extracts of these plants were used for synthesis of copper and zinc nanoparticles, as nanoparticles are powerful antimicrobial agents. The extract is prepared with a stock solution of 100mM copper sulphate and 100mM zinc sulphate. The leaf extracts were prepared with 5 solvents (Distilled water, Propane, Hexane, Acetone and Methanol). The action of plant leaves were observed by the zone of inhibition obtained with a concentration of 50, 100 and 150µl respectively. The result was more in copper nanoparticles of leaf extract as compared to the zinc nanoparticles of particular leaf extracts but the zinc particles with methanol and propane showed good result with particular leaves. In dried condition of leaves copper nanoparticles with propane as solvent exhibited a greater zone of inhibition. Moreover the solvent, methanol showed good results with both zinc and copper nanoparticles. The synthesized nanoparticle were characterized by UV-VIS spectrophotometry to confirm the formation of nanoparticles. Green synthesis is used namely because of low cost, simple, use of less toxic materials, most important is eco-friendly.
... In the 1-Ir route samples, as the irradiation dose increased, AgNPs' absorption peak at 400 nm diminished and became absent at the highest dose. This result could be explained that the high irradiation dose induced the PEG molecule degradation, hence their loss of protective ability on silver nanoparticles [1,57]. In addition, absorption signal of TNTs became more obvious as the dose augmented, indicating their higher crystallization. ...
Article
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In this work, silver nanoparticle- (AgNP-) embedded graphene oxide- (GO-) TiO2 nanotube (TNT) nanocomposite (labelled GAT) was successfully synthesized by gamma ray radiolysis. The influence of irradiation process, including one-step and two-step assistances and at different irradiation doses (5, 10, 15, 20, and 25 kGy), on the GAT’s physicochemical properties was achieved. Structure and properties of irradiated materials were analyzed by Fourier-transformed infrared (FT-IR), ultraviolet-visible absorption (UV-Vis), and Raman spectroscopies; X-ray diffraction (XRD); and scanning electron (SEM) and transmission electron (TEM) microscopies. In addition, selective scavengers of e⁻aq and ⋅OH radicals were used to investigate the radiolytic synthesis of GAT nanocomposite. It was revealed that gamma ray irradiation could strongly support the relation of the composite synthesis. Furthermore, the synthesized GAT nanocomposites showed a significant effect for Rhodamine B (RhB) photodecomposition after 60 minutes of natural sunlight exposure and evaluation by UV-Vis absorption spectroscopy. Briefly, the obtained results highlighted the potential of gamma irradiation as a “clean” and controllable way for synthesizing beneficial nanocomposite materials for wastewater purification and other environmental aspects.
Article
Silver nanoparticles (AgNPs) immobilized on polymer/silica hybrid nanoparticle is a model of functional, stable and dispersible additive for coating applications. The aim of this work is to modify silica nanoparticles (SiO2NPs) with poly 2-(dimethyl amino) ethyl methacrylate (PDMAEMA) brushes for template synthesis and immobilization of AgNPs using electron beam assisted grafting and reduction reactions. The PDMAEMA moieties were grafted onto vinyltrimethoxysilane (VTMS) modified SiO2NPs using pre-irradiation and peroxidation grafting approach. Several grafting parameters, i.e., pre-irradiation doses, DMAEMA monomer concentrations, reaction times and temperatures, were studied to optimize degree of grafting (DG). AgNPs were constructed on the SiO2NPs through the grafted PDMAEMA brushes as polymer shell template. AgNPs were successfully created on SiO2NPs-VTMS-PDMAEMA by electron-induced reduction reaction. DG of the PDMAEMA on SiO2NPs-VTMS was confirmed by gravimetric measurement, FTIR, TGA, TEM, FE-SEM. The nanostructure information and AgNPs immobilization were revealed by UV–Vis, TEM, SEM-EDX and XRD. The desirable grafting degree to obtain desirable appearance was 190%. The AgNPs on SiO2NPs-VTMS-PDMAEMA exhibited the characteristic absorbance of spherical Ag nanoarchitecture around 418 nm. The AgNPs immobilized SiO2NPs-VTMS-PDMAEMA efficiently inhibited the growth of fungi, i.e., Aspergillus niger and Syncephalatrum racemosum found on building materials.
Article
In this study, alternative transparent amorphous borosilicate glass systems incorporating metal oxides comprising PbO, BaO, and SrO at different concentrations were tested as gamma ray shielding materials. The mass attenuation coefficients (μm) and other shielding parameters were determined experimentally for the prepared samples at a photon energy of 662 keV (¹³⁷Cs source). X-ray diffraction analysis confirmed the amorphous nature of the prepared glass samples. The morphological structures of the glasses were characterized by scanning electron microscopy. Ultraviolet–visible spectroscopy was performed to determine the optical properties. The structural changes induced by the addition of metal oxides (PbO, SrO, and BaO) to the borosilicate glass were examined based on density measurements and Fourier transform-infrared spectroscopy. Finally, the results obtained for the prepared samples were compared in terms of the half value layer and density for some glass matrices used in industry comprising RD-30 and LX-57B, where the aim was to determine the effectiveness of the glass matrices at protecting against gamma radiations. The results showed that the shielding efficiencies of the borosilicate-based glasses containing high concentrations of BaO, PbO, and SrO were better than those of the glass matrices used in industry at present.
Article
The kinetic studies of preparation silver nanosquare (AgNS) and silver nanohexagon (AgNH) were made by rapid and green synthesis route using ziziphus spina-christi leaf powder with silver nitrate solution. The growth kinetics of silver nanoparticles as a function of time or pH were investigated. The optimal pH was studied by measuring the absorption maxima at different pH intervals (2-8) after treating the reducing agent with the silver nitrate solution. Moreover, the zeta potential was measured at different pHs for detecting the surface charge of Ag nanoparticles in its colloidal solution. The overall available silver ions after 2-25 min and the optimum Ag ion concentration were measured using inductively coupled plasma- optical emission spectroscopy (ICP-OES) technique. Furthermore, the time-dependent growth of crystalline was studied by measuring the increase in size along with the full width at half maximum (FWHM) that was taken from x-ray diffraction. The changes in the oxidation and reduction potentials of the Ag nanoparticles with time were studied to determine the optimum time. The prepared silver nanostructures at optimum conditions were characterized using electronic spectrum (UV-vis), infrared spectrum (IR), x-ray diffraction studies (XRD), zeta sizer, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive x-ray spectroscopy (EDX).
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We report a facile route for the green synthesis of trimethylchitosan nitrate-capped silver nanoparticles (TMCN-AgNPs) with positive surface charge. In this synthesis, silver nitrate, glucose, and trimethyl chitosan nitrate (TMCN) were used as silver precursor, reducing agent, and stabilizer, respectively. The reaction was carried out in a stirred basic aqueous medium at room temperature without the use of energy-consuming or expensive equipment. We investigated the effects of the concentrations of NaOH, glucose, and TMCN on the particle size, zeta potential, and formation yield. The AgNPs were characterized by UV-visible spectroscopy, photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of the TMCN-AgNPs was studied by the reduction of 4-nitrophenol using NaBH4 as a reducing agent. We evaluated the antibacterial effects of the TMCN-AgNPs on Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the broth microdilution method. The results showed that both gram-positive and gram-negative bacteria were killed by the TMCN-AgNPs at very low concentration (< 6.13 μg/mL). Moreover, the TMCN-AgNPs also showed high antibacterial activity against clinically isolated multidrug-resistant A. baumannii strains, and the minimum inhibitory concentration (MIC) was ≤ 12.25 μg/mL.
Article
We reported a simple, high yield and large-scale preparation method for silver nanoparticles. Silver nanoparticles with 8–13 nm in diameter were successfully synthesized by silver nitrate as raw material, sodium borohydride as reducing agent, dispersan-5040 (polycarboxylate sodium salt) as surface modifier in aqueous solution. The effects of sodium borohydride and dispersan-5040 on the morphologies of silver nanoparticles were investigated. Further, the conductive inks were prepared with as-synthesized silver nanoparticles as conductive fillers in the presence of deionized (DI) water and additives. The effects of conductive fillers and additives on the pH, conductivity, surface tension and viscosity of the inks were investigated. The conductive patterns were fabricated by inkjet printer and their performances were studied. The sheet resistances of the printed pattern with seven-layer was 1.2 [Formula: see text] when the printed pattern was heat-treated at 120[Formula: see text]C for 60 min. We succeeded in printing a simple conductive circuit on photographic paper, which can light three 0.06 W LED beads. The successful fabrication of the functional circuit proves the feasibility of the ink and provides some ideas for future paper-based circuits.
Article
In the present work, copper/chitosan nanocomposites (Cu/CS) were prepared in an aqueous solution in the presence of CS as stabilizer and CuSO4·5H2O precursor. The Cu/CS NPs formation was proved through transmission electron microscopy (TEM), Dynamic light scattering (DLS), Fourier Transform infrared (FT-IR) spectroscopy and XRD diffraction. Cotton and cotton/polyester fabrics were gamma-radiation grafted by padding to pickup of 100%, in nanocomposites based on Cu/CS NPs loaded in polymer blends of poly(vinyl alcohol) (PVA) and plasticized starch (PLST). The grafted fabrics were characterized in terms of tensile mechanical, crease recovery and water absorption properties. The results showed that cotton fabrics displayed higher water absorption (%) than cotton/polyester fabrics for all PVA/PLST compositions and water absorption was found to decrease with increasing the ratio of PVA in the PVA/PLST blends. Cotton/polyester fabrics displays crease recovery angle (CRA) value of 147.6 upon treated with PVA/PLST (80/20%) and gamma irradiated to 30 kGy compared to CRA value of 125.0 for cotton fabrics treated under the same conditions. For cotton fabrics, the tensile strength was largely depends on the irradiation dose, in which the tensile strength of the treated fabric with the different formulations is higher than the untreated fabric. The antimicrobial activity of the fabrics against gram-positive bacteria (Staphylococcus aurous) and gram-negative bacteria (Escherichia coli) was investigated. In case of gram-positive bacteria cotton fabric showed the highest impact, for both 50/50 and 20/80 PVA/PLST of 14 and 14.5 mm inhibition zone, whilst, cotton/polyester fabric recorded 6 and 5 mm inhibition zone against gram-negative bacteria for 50/50 and 20/80 PVA/PLST, respectively.
Chapter
Nanoparticles, ranging in the size from 1 to 100 nm possess novel or enhanced properties compared with larger particles of bulk materials, based on their specific characteristics such as size, distribution and morphology. Noble metal nanoparticles are widely used in the nano-medicinal application; especially silver nanoparticles, which exhibit antifungal, antibacterial, anti-plasmodial and anti-mosquito properties due to the unique properties such as chemical stability, good conductivity and catalytic activity. Nanoparticles are largely synthesized by a variety of chemical and physical approaches. These techniques being expensive and potentially hazardous to the environment, can pose various biological risks. This has necessitated for the alternate eco-friendly and innocuous approaches. In recent years, the convergence between the two fields; nanotechnology and biology; has evolved a new field of nanobiotechnology that encompasses a number of biochemical and biophysical processes employing biological entities such as algae, bacteria, fungi, viruses, yeasts, and plants. Focus on green synthesis of nanoparticles without employing toxic and expensive chemicals frequently used in conventional chemical and physical processes, has augmented their applications and safe usage. This chapter describes the different methods to synthesize silver nanoparticles with a major focus on synthesizing nanoparticles via green route i.e., by utilizing biological entities for the facile, eco-friendly and cost-effective synthesis.
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Practically, 12% of used dyes are excluded as waste in the mobile aqueous environment. Methyl orange (MO), an industrial azo dye, is known to be carcinogenic. Accordingly, this work was engaged to fabrication of a high-efficiency visible light photocatalysts based on Ag-Alginate/Chitosan-coated MgO nanocomposite beads. MgO and Ag were prepared via precipitation and γ-radiation reduction technique as a green physical one, respectively. The degradation mechanisms depended on catalytic reduction by means of sodium borohydride/Ag and photo oxidative degradation. XRD proved the periclase crystalline form of MgO of size 20 nm and the formation of face centered cubic silver crystals of size 15 nm. The degradation yield varied directly with time, MgO and dye concentration until certain limit. Five and twenty minutes were enough to get clear solution of MO (30 and 15 ppm, respectively) while 60 min was required to achieve the same target for 60 ppm MO solution. The catalysts showed high efficiency for MO of high concentration. The incorporation of Ag into catalytic beads could support both mechanisms as it could elevate the degradation efficiency up to 50% and save the time to a great extent. Thus, this carrier fruitfully converted wastewater into an effluent that can be repaid to the water cycle with minimal strike on the ecosystem.
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Replacing packaging plastics with biodegradable active materials is an emerging concern. In this context, thermoplastic starch (TPS) films and nanocomposites containing different concentrations of silver nanoparticles synthetized with starch and yerba mate (TPS-AgNP1: 0.006 wt.% and TPS-AgNP2: 0.015 wt.%) were developed by extrusion and compression molding. Spherical AgNP of 20-130 nm were obtained after the green synthesis and excellent adhesion between AgNP and the matrix was observed. Consequently, both composites exhibited higher stiffness and tensile strength values than TPS, indicating a reinforcing effect of AgNP. TPS-AgNP1 showed the highest strain at break and toughness values, and TPS-AgNP2 presented the lowest moisture content and ability to delay E. coli growth. Additionally, all materials disintegrated after 4 weeks of burial and resulted thermally stable up to 240 °C. This investigation provides a convenient and inexpensive way to develop starch-based nanocomposites with improved properties which appear to be promising as active packaging materials.
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Extensive research has been conducted on a variety of processes for abating the increasing CO2 emissions which have been causing adverse effects on the environment. Among these, gas separation membranes have the potential to overcome a number of limitations of existing technologies by reducing the cost of operations and providing an efficient, compact module which can be employed for separating CO2 from natural gas and post‐combustion flue gas streams. Recently, chitosan and its derivatives have proven their ability to form CO2‐selective facilitated transport membranes through the utilization of the amino group fixed site carriers present in the polymer. Later, the performance of chitosan membrane can be substantially improved by carrier enrichment. This review aims to cover the structure‐property relations of chitosan and its film‐forming derivatives, with a brief discussion of the advantages and challenges in using these polymers. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.
Article
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Nanomaterials with antimicrobial activity are promising alternatives to overcome microbial resistance in medical devices. Catheters, probes, and wound dressings are among the medical devices mostly affected by microbial contamination and the formation of polymicrobial biofilms. Nanoparticles (NPs) derived from natural sources, such as chitosan nanoparticles (CsNPs), and metal‐based nanoparticles, including silver nanoparticles (AgNPs), are receiving increased interest in nanomedicine. CsNPs have been widely explored as a coating material and antimicrobial agent. AgNPs have a strong antimicrobial effect against bacteria and fungi. The nanocomposite chitosan–silver nanoparticles (Cs‐AgNPs) can be more effective against several microorganisms, including multidrug‐resistant bacteria, due to the synergistic effect between chitosan and silver. This review addresses the most used synthesis methods, including green routes, to produce CsNPs, AgNPs, and Cs–AgNPs. It also discusses physicochemical characteristics and antimicrobial properties of these NPs in medical, pharmaceutical, and biotechnological areas.
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In recent years, bionanotechnology and green chemistry are received more attention among the researchers as they are eco-friendly and cost-effective techniques to prepare nanomaterials. Herein we report the synthesis of silver nanoparticles (AgNPs) using Biophytum Sensitivum (B. Sensitivum) leaf extract. Synthesized AgNPs were primarily confirmed by UV–visible spectroscopy. It shows the surface plasmon resonance at 460 nm. The size and morphology of synthesized B. Sensitivum capped AgNPs was confirmed by transmission electron microscopy (TEM). It shows the prepared AgNPs were well dispersed and spherical in shape with average diameter of 8 nm. Further, B. Sensitivum capped AgNPs were modified on glassy carbon electrode (GCE) surface and the electrochemical characterization was carried out using cyclic voltammogram. It shows the anodic peak at 0.27 V which corresponds to the formation of silver into silver oxide. Further, the electrocatalytic behavior of B. Sensitivum capped AgNPs were examined by dioxygen reduction. It was found that the B. Sensitivum capped AgNPs modified GCE exhibits enhanced electrocatalytic activity towards dioxygen reduction when compared to bare GCE.
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Soil borne diseases which are caused to various plants include a wide variety of soil microbes like fungi and bacteria, among which Fusarium wilt is one such disease caused by Fusarium oxysporum cubense in banana plants. Wilt disease or the panama disease of plant is among the most destructive disease of banana in the tropics and even the control methods like field sanitation, soil treatments and crop rotations have not been a long term control for this disease. An alternative method of treating Fusarium oxysporum was adopted by using various natural plant leaves of Ocimum tenuiflorum and Tabernaemontana divaricate. Nanoparticles are small particles with a dimension of 10-9 and 10-10. Green synthesis is a new method developed for the synthesis of nanoparticles which is small in size, large surface area and eco- friendly. Leaf extracts of these plants were used for synthesis of copper and zinc nanoparticles, as nanoparticles are powerful antimicrobial agents. The extract is prepared with a stock solution of 100mM copper sulphate and 100mM zinc sulphate. The leaf extracts were prepared with 5 solvents (Distilled water, Propane, Hexane, Acetone and Methanol). The action of plant leaves were observed by the zone of inhibition obtained with a concentration of 50, 100 and 150µl respectively. The result was more in copper nanoparticles of leaf extract as compared to the zinc nanoparticles of particular leaf extracts but the zinc particles with methanol and propane showed good result with particular leaves. In dried condition of leaves copper nanoparticles with propane as solvent exhibited a greater zone of inhibition. Moreover the solvent, methanol showed good results with both zinc and copper nanoparticles. The synthesized nanoparticle were characterized by UV-VIS spectrophotometry to confirm the formation of nanoparticles. Green synthesis is used namely because of low cost, simple, use of less toxic materials, most important is eco-friendly.
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The modification of medical devices is an area that has attracted a lot of attention in recent years; particularly, those developments which search to modify existing devices to render them antimicrobial. Most of these modifications involve at least two stages (modification of the base material with a polymer graft and immobilization of an antimicrobial agent) which are both time-consuming and complicate synthetic procedures; therefore, as an improvement, this project sought to produce antimicrobial silicone (PDMS) in a single step. Using gamma radiation as both an energy source for polymerization initiation and as a source of reducing agents in solution, PDMS was simultaneously grafted with acrylic acid and ethylene glycol dimethacrylate (AAc:EGDMA) while producing antimicrobial silver nanoparticles (AgNPs) onto the surface of the material. To obtain reproducible materials, experimental variables such as the effect of the dose, the intensity of radiation, and the concentration of the silver salt were evaluated, finding the optimal reaction conditions to obtain materials with valuable properties. The characterization of the material was performed using electronic microscopy and spectroscopic techniques such as 13C-CPMAS-SS-NMR and FTIR. Finally, these materials demonstrated good antimicrobial activity against S. aureus while retaining good cell viabilities (above 90%) for fibroblasts BALB/3T3.
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The present study focuses on utilising gamma irradiation to prepare Poly (PVP/acrylamide/glycerol/bentonite clay) nanocomposite film poly(PVP/AAm/Glyc/BNTN) with composition (40/60/5/0.25 wt %) at different doses of 10, 20, 30 and,40 kGy. The FTIR analysis shows the successful preparation and modification of the different irradiated poly(PVP/AAm/Glyc/BNTN) nanocomposite film at different doses. The film irradiated at 40 kGy is a stable film that has higher water resistance properties than other prepared films as shown in the swelling study. The bentonite nano clay was found to be homogeneously and well distributed in the surface of the nanocomposite film modified at 40 kGy, which led to the chemical stability of the synthesised poly(PVP/AAm/Glyc/BNTN) with composition (40/60/5/0.25 wt %) as shown in the swelling study, and field emission scan electron microscope (FESEM). Also, the bentonite nanoparticles have an average particle size of 76.5 nm. The impacts of the different factors which include pH, contact time (h.), and temperature (k) on the uptake of Acid red 37 (AR 37) dye from its aqueous solution were investigated. The Langmuir model was established as the suitable model for this work and the uptake of AR 37 dye was designated by the pseudo-second-order kinetic model to be spontaneous and endothermic. Furthermore, the adsorption capacity was enhanced with the temperature and time and reduced with increasing the pH of the dye solution. The maximum adsorption capacity of Poly(PVP/AAm/Glyc/BNTN) samples to the anionic AR 37 dye was found to be 136.13 mg/g at pH 4, contact time 8 hrs, and amount of adsorbent 0.3 g/100 ml of the dye solution.
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An effective method for reducing silver ions using gelatin (Gel) and 2-hydroxypropyl-β-cyclodextrin (HPCD) hydrogels, which stabilize silver at various concentrations is described. The formation of AgNPs in solution, as well as Gel-HPCD nanogels, is confirmed by the surface plasmon resonance (SPR) band at 420–440 nm in the UV–Vis spectrum. The resulting Gel-HPCD and Gel-HPCD/AgNPs composites are characterized using various techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and thermogravimetric analysis (TGA). SEM images showed that the porous structure and the AgNPs are homogeneously dispersed throughout the Gel-HPCD/AgNP composites network. The AgNPs in the Gel-HPCD/AgNPs composite is crystalline, with spherical particles having an average size of 7.0 ± 2.5 nm, as determined by TEM. The Gel-HPCD/AgNPs composites are strongly effective against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The assembled antibacterial Gel-HPCD/AgNPs composites are also assessed for their cytotoxic and anticancer activities using HCT-116 cancer cells. The results suggest that Gel-HPCD/AgNPs composites could be used as effective therapeutics in the future in tissue engineering applications, as their bactericidal properties and low toxicity make them ideal for clinical use.
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In this project, a bio-based heterogeneous catalyst is synthesized via multi steps process. First, nano-rod hydroxyapatite modified by silica compound is prepared, functionalized with of some nitrogen sources linkages such as, 4-aminoacetanilide and consequent immobilization of Ag nanoparticles by Sorbus aucuparia extract. The as-prepared catalyst, [email protected]@SiO2-TAA, was successfully characterized by using FTIR, XRD, BET, SEM/EDX, TGA, TEM, ICP-AES and elemental mapping analysis. Furthermore, metal-ligand interactions in [email protected]@SiO2-TAA complex models were assessed to interpret the immobilization behavior of Ag-NPs on the surface of nano-rod hydroxyapatite through quantum chemistry computations. The catalytic activity of the [email protected]@SiO2-TAA was investigated in multi-component Hantzcsh reactions under mild conditions to furnish the corresponding products in high yields and short reaction times. Moreover, the recyclability study and Ag leaching of the [email protected]@SiO2-TAA verified that the catalyst could be easily recovered and also recycled up to six runs with only slight loss of activity.
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Soil borne diseases which are caused to various plants include a wide variety of soil microbes like fungi and bacteria, among which Fusarium wilt is one such disease caused by Fusarium oxysporum cubense in banana plants. Wilt disease or the panama disease of plant is among the most destructive disease of banana in the tropics and even the control methods like field sanitation, soil treatments and crop rotations have not been a long term control for this disease. An alternative method of treating Fusarium oxysporum was adopted by using various natural plant leaves of Gliricidia sepium and Piper nigrum. Nanoparticles are small particles with a dimension of 10-9 and 10-10. Green synthesis is a new method developed for the synthesis of nanoparticles which is small in size, large surface area and eco- friendly. Leaf extracts of these plants were used for synthesis of copper and zinc nanoparticles, as nanoparticles are powerful antimicrobial agents. The extract is prepared with a stock solution of 100mM copper sulphate and 100mM zinc sulphate. The leaf extracts were prepared with 5 solvents (Distilled water, Propane, Hexane, Acetone and Methanol). The action of plant leaves were observed by the zone of inhibition obtained with a concentration of 50, 100 and 150µl respectively. The result was more in copper nanoparticles of leaf extract as compared to the zinc nanoparticles of particular leaf extracts but the zinc particles with methanol and propane showed good result with particular leaves. In dried condition of leaves copper nanoparticles with propane as solvent exhibited a greater zone of inhibition. Moreover the solvent, methanol showed good results with both zinc and copper nanoparticles. The synthesized nanoparticle were characterized by UV-VIS spectrophotometry to confirm the formation of nanoparticles. Green synthesis is used namely because of low cost, simple, use of less toxic materials, most important is eco-friendly.
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This work provide a new method for the preparation of nanofibers act as bifunctional photocatalytic nano-materials to degrade organic pollutants in water and soil systems effectively. Using PLA fibers as the carrier of Cu2O nanoparticles, Cu2O/PLA composite nanofibers were fabricated by surface modification induced via electron beam irradiation. During this treatment, carbonyl groups and hydroxyl groups from the surface of PLA and Cu2O were conjugated by strong hydrogen bonding effect, while the Cu2O nanoparticles was evenly distributed without agglomeration. Thus obtained composite nanofibers exhibited excellent photocatalytic performance and enhanced antibacterial activities against Staphylococcus aureus and Escherichia coli.
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We present a simple method for the optical manipulation and spectroscopy of colloidal silver nanoparticles in aqueous solution using optical tweezers combined with dark-field microscopy. Because of their localized plasmon resonances, single trapped metal nanoparticles can be used as efficient near-field optical probes, with potential applicability in surface-enhanced spectroscopy, near-field microscopy, and biochemical sensing schemes. As a proof of principle, we study the near-field optical interaction between a trapped and an immobilized Ag nanoparticle.
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Several differently prepared silver sols and a gold sol were examined using electron microscopy optical absorption and microelectrophoresis techniques. The effects of 4-dimethyl-amino-pyridine and pyridine addition to the sols were also studied. In all cases of amine adsorption onto the sol particles, an accompanying decrease in the magnitude of the electrophoretic mobility of the particles was observed, and a long wavelength (>500 nm) absorption band was formed. The solution species responsible for these changes is an aggregate composed of the primary sol.
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The nanocomposites of stable nanosilver particles embedded in polyacrylonitrile matrix were synthesized by /gamma-irradiation, in which the monomer acrylonitrile was polymerized and the silver ions were reduced simultaneously by /gamma-irradiation to form composites in situ. The strong interactions between silver ions with -CN groups of polyacrylonitrile are found, which were confirmed by X-ray powder diffraction, IR spectrum and absorption spectra.
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Poly(acrylic acid)–metal nanocomposites were synthesized by irradiating the solutions of metal ions (Ag+, Cu2+, Ni2+) in acrylic acid monomer with γ-ray. The products are characterized by XRD and TEM. It was found that the nanometer metal particles are well dispersed in poly(acrylic acid) with a narrow-size distribution.
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Polyacrylamide–silver nanocomposites with a silver particle size distribution ranging from 2 to 20 nm in a polyacrylamide matrix are synthesized by γ-irradiation at room temperature.
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Electron-transfer processes between simple 1-hydroxyalkyl, 1-ethoxyethyl, and 2-hydroxycyclohexadienyl radicals and metal ions at the surface of colloidal silver are described. C6H6OH radicals are oxidized by Ag+ to yield phenol. In the absence of Ag+, no electron exchange between C6H6OH and the silver particles takes place. When the silver particles carry a tiny deposit of thallium metal, the C6H6OH radicals are reduced. Cu+ (and Cu2+) ions adsorbed on the silver particles oxidize C6H6OH radicals. However, reduction of C6H6OH by Cu+ occurs, if the silver particles are covered with copper metal. 1-Hydroxyalkyl and 2-ethoxyethyl radicals reduce Tl+ ions in the presence of colloidal silver, but oxidize Tl atoms in homogeneous solution. Water can be decomposed to yield H2 by 1-hydroxy-1-methyl and 1-hydroxyethyl, but not by 1-hydroxymethyl, 1-ethoxyethyl, and 2-hydroxycyclohexadienyl radicals. These findings are discussed in terms of standard potentials for the oxidation and reduction of the radicals and in terms of distributions of occupied and unoccupied electronic redox levels in the radicals and the colloidal metal. In these experiments γ radiolysis was used to produce the radicals at a controlled rate.
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Ag+ ions, in aqueous polyvinyl alcohol (PVA) solution and in PVA hydrogel matrix have been gamma radiolytically reduced to produce Ag clusters. UV-visible absorption spectral characteristics of Ag clusters obtained under different gamma dose, Ag+ concentration, PVA concentration and crosslinking density of the gel used have been studied. The effect of Ag+ ions on the radiation crosslinking of the PVA chains, have also been investigated by viscosity measurements. The radiation-induced Ag+ ion reduction was followed by crosslinking of the PVA chains. PVA was found to be a very efficient stabilizer to prevent aggregation of Ag clusters. The clusters produced in the hydrogel matrix were expected to be smaller than the pore size (∼2–20nm) of the gels used in the study. These Ag clusters were unable to reduce methyl viologen (MV2+) chloride and were stable in air.
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A report on the structure of trimer silver crystal Ag32+ was presented in the article. During the growth of small colloidal silver clusters in aqueous solution, the trimer silver ion exhibits a remarkable behavior in that this species represents the changeover from pseudo-first-order reaction mechanisms to second-order mechanisms. This model explained experimental observations such as the relative stability of trimer clusters and also the formation of silver clusters of a specific number of atoms i.e., the 'magic' clusters.
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The nanocomposites of stable nanosilver particles embedded in polyacrylonitrile matrix were synthesized by γ-irradiation, in which the monomer acrylonitrile was polymerized and the silver ions were reduced simultaneously by γ-irradiation to form composites in situ. The strong interactions between silver ions with –CN groups of polyacrylonitrile are found, which were confirmed by X-ray powder diffraction, IR spectrum and absorption spectra.
Article
Colloidal silver has been formed either by irradiation with 253.7 nm light or by chemical reduction of AgClO4 in the presence of protective agents such as poly(vinylpyrrolidone), carboxy methyl cellulose, and gelatin. The particles were characterized by their absorption maximum and transmission electron micrographs. Peptization effect was observed in the presence of photosensitive benzophenone. Surface modification studies of silver particles in the presence of various complexing agents, viz., N-(hydoxyethyl)ethylenediaminetriacetic acid, iminodiacetic acid, nitrilotriacetic acid, 2-mercaptobenzimidazole, benzotriazole, 5-aminotetrazole, imidazole, and sanazole were carried out and it was shown that the reactivity of silver particles increases in their presence. However, in the presence of stabilizers, due to competitve reactions, partial recovery of the surface plasmon absorption band was observed. The Fermi potential of surface modified silver particles seems to lie in the range of −0.40 ± 0.05 V.
Article
Ag(CN)2- is reduced at a low rate by radiolytically generated hydroxymethyl radicals. The reduction occurs on tiny nuclei in solution formed by hydrolysis. When colloidal silver seed particles are present in the solution, the reduction of Ag(CN)2- is much faster, and larger silver particles with a narrow size distribution are produced. A mechanism is proposed, in which the •CH2OH radicals transfer electrons to the seed particles, and the stored electrons finally reduce Ag(CN)2- directly on the surface of the seeds. The limitations of this kind of radiolytic particle enlargement are discussed. In the presence of colloidal platinum, Ag(CN)2- is also rapidly reduced by the organic radicals. Bimetallic particles of the PtcoreAgshell type with a rather nonsymmetric shape of the shell are formed; despite this irregular structure, the optical spectra agree fairly well with literature spectra calculated for symmetric bimetallic particles.
Article
Organic free radicals of high negative redox potential such as ..cap alpha..-alcohol radicals were found to transfer electrons to colloidal silver particles stabilized by sodium dodecyl sulfate in aqueous solution. The colloidal particles thus became a pool of stored electrons that could reduce water to form hydrogen or react with suitable acceptors in solution. The organic radicals were produced by irradiation, using suitable scavengers for the primary radicals from the radiolysis of the aqueous solvent. The solutions initially contained silver ions at 1 x 10⁻⁴ - 2 x 10⁻³ M. At doses below 10⁵ rd, the silver ions were completely reduced to form the colloidal catalyst. In this dose range, the corresponding hydrogen yield amounted to 1 molecule per 100 eV. It increased steeply at higher doses up to 3 molecules per 100 eV. The Hâ yield decreased with increasing dose rate and with increasing pH in alkaline solutions. It was highest at a concentration of sodium dodecyl sulfate of 1 x 10⁻³ M, i.e., far below the critical micelle concentration of this surfactant. Changes in the absorption spectrum of the colloid are attributed to changes in the size of the silver particles upon charging up with electrons. The competition of radical-colloid reactions with radical-radical deactivation in the bulk of solution or at the surface of the colloidal particles is also discussed. 11 figures.
Article
Ag+ ions are reduced in aqueous solutions by a short pulse of high-energy radiation. At the low radiation dose applied, second-order reactions of the early intermediates are negligible. Three elementary processes occur during microseconds after the pulse, in each of which Ag+ is a reactant: e(aq)(-) + Ag+ --> Ag-0 (k = 4.8 x 10(10) M(-1) s(-1)); Ag-0 + Ag+ --> Ag-2(+) (k = 8.5 x 10(9) M(-1) s(-1)); Ag-2(+) + Ag+ --> Ag-3(2+) (k = 2.0 X 10(9) M(-1) s(-1)). The reactions overlap temporally. Computer simulation is used to obtain the rate constants and the absorption spectra of the three species involved. Ag-3(2+) has not yet been detected in water at ambient temperature; it was known to exist only in zeolite cages and frozen organic glasses.
Article
Silver nanoparticles were synthesized by irradiating solutions, prepared by mixing AgNO3 and poly-vinyl alcohol (PVA), with 6 MeV electrons. The electron-irradiated solutions and the thin coatings cast from them were characterized using the ultraviolet–visible (UV–vis), x-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. During electron irradiation, the process of formation of the silver nanoparticles appeared to be initiated at an electron fluence of ~2 × 1013 e cm−2. This was evidenced from the solution, which turned yellow and exhibited the characteristic plasmon absorption peak around 455 nm. Silver nanoparticles of different sizes in the range 60–10 nm, with a narrow size distribution, could be synthesized by varying the electron fluence from 2 × 1013 to 3 × 1015 e cm−2. Silver nanoparticles of sizes in the range 100–200 nm were also synthesized by irradiating an aqueous AgNO3 solution with 6 MeV electrons.
Article
Ag/cross-linked poly(vinyl alcohol) (PVA) cable-like nanostructures were synthesized with control in an aqueous solution of a hydrolysable amphiphilic block polymer, poly(vinyl acetone) (PVKA) (ketalization degree DH = 0.533) under γ-ray irradiation, via one-step in situ reduction of Ag+ and cross-linking of alcohol units. In the present approach, we try to control the speed of the cross-linking reaction of PVA chains (alcohol units), which are yielded from the hydrolysed PVKA, utilizing the low hydrolysis rate of the PVKA in dilute acidic solution.
Article
Ag nanoparticles were synthetized in the interlamellar space of a layered kaolinite clay mineral. Disaggregation of the lamellae of non-swelling kaolinite was achieved by intercalation of dimethyl sulfoxide. The kaolinite was suspended in aqueous AgNO3 solution and, after adsorption of Ag+, the ions were reduced with NaBH4. The interlamellar space limits particle growth (dave=3.8–4.2 nm); however, larger silver particles may be formed on the exterior surface of kaolinite with dave=5.6–10.5 nm diameter. The diameter of the particles prepared in this way is depending on the initial AgNO3 concentration. The silver nanoparticles prepared were characterized by UV–vis spectroscopy, X-ray diffraction (XRD), Small angle X-ray scattering (SAXS), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM).
Article
The elucidation of the long range distance dependence of the localized surface plasmon resonance (LSPR) of surface-confined noble metal nanoparticles is the aim of this work. It was suspected that the linear distance dependence found in CH 3 (CH 2) x SH self-assembled monolayer (SAM) formation was the thin shell limit of a longer range, nonlinear dependence. To verify this, multilayer SAM shells based on the interaction of HOOC-(CH 2) 10 SH and Cu 2+ were assembled onto surface-confined noble metal nanoparticles and were monitored using UV-visible spectroscopy. Measurement of the LSPR extinction peak shift versus number of layers and adsorbate thickness is nonlinear and has a sensing range that is dependent on the composition, shape, in-plane width, and out-of-plane height of the nanoparticles. Theoretical calculations based on an accurate electrodynamics description of the metal nanoparticle plus surrounding layered material indicate plasmon resonance wavelength shifts that are in excellent agreement with the measurements. The calculations show that the sensing range is determined by falloff of the average induced electric field around the nanoparticle. This detailed set of experiments coupled with an excellent theory versus experiment comparison prove that the sensing capabilities of noble metal nanoparticles can be size tuned to match the dimensions of biological and chemical analytes by adjusting the aforementioned properties. The optimization of the LSPR nanosensor for a specific analyte will significantly improve an already sensitive nanoparticle-based sensor.
Article
Silver and gold nanotriangles were fabricated by nanosphere lithography (NSL) and their localized surface plasmon resonance (LSPR) spectra were measured by UV-vis extinction spectroscopy. It is demonstrated that the short range (viz., 0-2 nm) distance dependence of the electromagnetic fields that surround these nanoparticles when resonantly excited can be systematically tuned by changing their size, structure, and composition. This is accomplished by measuring the shift in the peak wavelength, λ max , of their LSPR spectra caused by the adsorption of hexadecanethiol as a function of nanoparticle size (in-plane width, out-of-plane height, and aspect ratio), shape (truncated tetrahedron versus hemisphere), and composition (silver versus gold). We find that the hexadecanethiol-induced LSPR shift for Ag triangles decreases when in-plane width is increased at fixed out-of-plane height or when height is increased at fixed width. These trends are the opposite to what was seen in an earlier study of the long range distance dependence in which 30 nm thick layers were examined (Haes et al. J. Phys. Chem. B 2004, 108, 109), but both the long and short range results are confirmed by a theoretical analysis based on finite element electrodynamics. The theory results also indicate that the short range results are primarily sensitive to hot spots (regions of high induced electric field) near the tips of the triangles, so this provides an example where enhanced local fields play an important role in extinction spectra. Our measurements further show that the hexadecanethiol-induced LSPR peak shift is larger for nanotriangles than for hemispheres with equal volumes and is larger for Ag nanotriangles than for Au nanotriangles with the same in-plane widths and out-of-plane heights. The dependence of the alkanethiol-induced LSPR peak shift on chain length for Ag nanotriangles is approximately size-independent. We anticipate that the improved understanding of the short range dependence of the adsorbate-induced LSPR peak shift on nanoparticle structure and composition reported here will translate to significant improvements in the sensitivity of refractive-index-based nanoparticle nanosensors.
Article
Gamma radiolysis method was used to prepare polyvinyl alcohol (PVA) capped silver nanoparticles by optimizing various conditions like metal ion concentration and polymer (PVA) of different molecular weights. The role of different scavengers was also studied. The decrease in particle size was observed with increase in the molecular weight of capping agent. γ-radiolytic method provides silver nanoparticles in fully reduced and highly pure state. XRD (X-ray diffraction) technique confirmed the zero valent state of silver. Optical studies were done using UV-visible spectrophotometer to see the variation of electronic structure of the metal sol. Transmission Electron Microscopic (TEM) studies reveal the fcc geometry. The TEM show clearly split Debye-Scherrer rings. The d values calculated from the diffraction ring pattern are in perfect agreement with the ASTM data. Ag particles less than 10 nm are spherical in shape, whereas the particles above 30 nm have structure of pentagonal biprisms or decahedra, referred to as multiply twinned particles.
Article
The labeling of biological species using dyes has become common practice to aid in their detection, and immediate positive identification of specific dyes in high dilution is a key requirement. Here the detection by surface-enhanced resonance Raman scattering (SERRS) of eight commercially available dye labels (ROX, rhodamine 6G, HEX, FAM, TET, Cy3, Cy5, TAMRA) attached to oligonucleotide strands is reported. Each of the eight labels was easily detected by using the SERRS from silver nanoparticles to produce a unique, molecularly specific spectrum. The conditions were optimized to obtain the best signal enhancement, and linear concentration graphs at low oligonucleotide concentrations were obtained. At higher concentrations (above approximately 10(-)(8) mol dm(-)(3)), curvature was introduced into the concentration graphs with the exception of rhodamine 6G, TET, and FAM, which gave linearity over the entire concentration range studied. Detection limits as low as 0.5 fmol were obtained, with lower possible if a smaller sample was analyzed. Investigation was also carried out into the effect of a Tris-HCl buffer containing the surfactant Tween 20 to aid in the prevention of surface adhesion of the oligonucleotides to the sample vessels at ultralow concentrations. The Tween 20 allowed lower detection limits to be obtained for each of the labels studied. This study shows that the different dyes commonly used with oligonucleotides can give quantitative SERRS at concentration levels not possible when the same dyes are used with fluorescence detection.
Article
Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and gamma-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution, but increases with increasing its molecular weight. Further, TEM showed that the silver nanoparticles become disassembled into smaller nanoparticles after dilution with distilled water and sonication. Since the processes of dilution and sonication are not expected to result in chemical reactions or to split the silver nanoparticles, we conclude that each silver nanoparticle prepared by [Formula: see text] -irradiation consists of several smaller nanoparticles surrounded by PVP. Thus, based on these observations, we propose a three-step mechanism for the growth of the silver nanoparticles under the conditions considered here. In the first step, the silver ions interact with PVP, then in the second step the silver ions that are exposed to gamma-irradiation are reduced to silver atoms; nearby silver atoms then aggregate at close range. These aggregates are the primary nanoparticles. Finally, these primary nanoparticles coalesce with other nearby primary nanoparticles or interact with PVP to form larger aggregates which are the secondary (final) nanoparticles.