Sample records for nanoparticles ag nps

  1. Comparative Study of Antimicrobial Activity of AgBr and Ag Nanoparticles (NPs)

    PubMed Central

    Suchomel, Petr; Kvitek, Libor; Panacek, Ales; Prucek, Robert; Hrbac, Jan; Vecerova, Renata; Zboril, Radek

    2015-01-01

    The diverse mechanism of antimicrobial activity of Ag and AgBr nanoparticles against gram-positive and gram-negative bacteria and also against several strains of candida was explored in this study. The AgBr nanoparticles (NPs) were prepared by simple precipitation of silver nitrate by potassium bromide in the presence of stabilizing polymers. The used polymers (PEG, PVP, PVA, and HEC) influence significantly the size of the prepared AgBr NPs dependently on the mode of interaction of polymer with Ag+ ions. Small NPs (diameter of about 60–70 nm) were formed in the presence of the polymer with low interaction as are PEG and HEC, the polymers which interact with Ag+ strongly produce nearly two times bigger NPs (120–130 nm). The prepared AgBr NPs were transformed to Ag NPs by the reduction using NaBH4. The sizes of the produced Ag NPs followed the same trends – the smallest NPs were produced in the presence of PEG and HEC polymers. Prepared AgBr and Ag NPs dispersions were tested for their biological activity. The obtained results of antimicrobial activity of AgBr and Ag NPs are discussed in terms of possible mechanism of the action of these NPs against tested microbial strains. The AgBr NPs are more effective against gram-negative bacteria and tested yeast strains while Ag NPs show the best antibacterial action against gram-positive bacteria strains. PMID:25781988

  2. Antifungal Effects of Silver Nanoparticles (AgNPs) against Various Plant Pathogenic Fungi.

    PubMed

    Kim, Sang Woo; Jung, Jin Hee; Lamsal, Kabir; Kim, Yun Seok; Min, Ji Seon; Lee, Youn Su

    2012-03-01

    This research is concerned with the fungicidal properties of nano-size silver colloidal solution used as an agent for antifungal treatment of various plant pathogens. We used WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R silver nanoparticles (AgNPs) at concentrations of 10, 25, 50, and 100 ppm. Eighteen different plant pathogenic fungi were treated with these AgNPs on potato dextrose agar (PDA), malt extract agar, and corn meal agar plates. We calculated fungal inhibition in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. The results indicated that AgNPs possess antifungal properties against these plant pathogens at various levels. Treatment with WA-CV-WB13R AgNPs resulted in maximum inhibition of most fungi. Results also showed that the most significant inhibition of plant pathogenic fungi was observed on PDA and 100 ppm of AgNPs.

  3. Differential Phytotoxic Impact of Plant Mediated Silver Nanoparticles (AgNPs) and Silver Nitrate (AgNO3) on Brassica sp.

    PubMed Central

    Vishwakarma, Kanchan; Shweta; Upadhyay, Neha; Singh, Jaspreet; Liu, Shiliang; Singh, Vijay P.; Prasad, Sheo M.; Chauhan, Devendra K.; Tripathi, Durgesh K.; Sharma, Shivesh

    2017-01-01

    Continuous formation and utilization of nanoparticles (NPs) have resulted into significant discharge of nanosized particles into the environment. NPs find applications in numerous products and agriculture sector, and gaining importance in recent years. In the present study, silver nanoparticles (AgNPs) were biosynthesized from silver nitrate (AgNO3) by green synthesis approach using Aloe vera extract. Mustard (Brassica sp.) seedlings were grown hydroponically and toxicity of both AgNP and AgNO3 (as ionic Ag+) was assessed at various concentrations (1 and 3 mM) by analyzing shoot and root length, fresh mass, protein content, photosynthetic pigments and performance, cell viability, oxidative damage, DNA degradation and enzyme activities. The results revealed that both AgNPs and AgNO3 declined growth of Brassica seedlings due to enhanced accumulation of AgNPs and AgNO3 that subsequently caused severe inhibition in photosynthesis. Further, the results showed that both AgNPs and AgNO3 induced oxidative stress as indicated by histochemical staining of superoxide radical and hydrogen peroxide that was manifested in terms of DNA degradation and cell death. Activities of antioxidants, i.e., ascorbate peroxidase (APX) and catalase (CAT) were inhibited by AgNPs and AgNO3. Interestingly, damaging impact of AgNPs was lesser than AgNO3 on Brassica seedlings which was due to lesser accumulation of AgNPs and better activities of APX and CAT, which resulted in lesser oxidative stress, DNA degradation and cell death. The results of the present study showed differential impact of AgNPs and AgNO3 on Brassica seedlings, their mode of action, and reasons for their differential impact. The results of the present study could be implied in toxicological research for designing strategies to reduce adverse impact of AgNPs and AgNO3 on crop plants. PMID:29075270

  4. Influence of particle coating and matrix constituents on the cloud point extraction efficiency of silver nanoparticles (Ag-NPs) and application for monitoring the formation of Ag-NPs from Ag(+).

    PubMed

    Hartmann, Georg; Baumgartner, Tanja; Schuster, Michael

    2014-01-07

    For the quantification of silver nanoparticles (Ag-NPs) in environmental samples using cloud point extraction (CPE) for selective enrichment, surface modification of the Ag-NPs and matrix effects can play a key role. In this work we validate CPE with respect to the influence of different coatings and naturally occurring matrix components. The Ag-NPs tested were functionalized with inorganic and organic compounds as well as with biomolecules. Commercially available NPs and NPs synthesized according to methods published in the literature were used. We found that CPE can extract almost all Ag-NPs tested with very good efficiencies (82-105%). Only Ag-NPs functionalized with BSA (bovine serum albumin), which is a protein with the function to keep colloids in solution, cannot be extracted. No or little effect of environmentally relevant salts, organic matter, and inorganic colloids on the CPE of AgNPs was found. Additionally we used CPE to observe the in situ formation of Ag-NPs produced by the reduction of Ag(+) with natural organic matter (NOM).

  5. Role of silver nanoparticles (AgNPs) on the cardiovascular system.

    PubMed

    Gonzalez, Carmen; Rosas-Hernandez, Hector; Ramirez-Lee, Manuel Alejandro; Salazar-García, Samuel; Ali, Syed F

    2016-03-01

    With the advent of nanotechnology, the use and applications of silver nanoparticles (AgNPs) have increased, both in consumer products as well as in medical devices. However, little is known about the effects of these nanoparticles on human health, more specific in the cardiovascular system, since this system represents an important route of action in terms of distribution, bioaccumulation and bioavailability of the different circulating substances in the bloodstream. A collection of studies have addressed the effects and applications of different kinds of AgNPs (shaped, sized, coated and functionalized) in several components of the cardiovascular system, such as endothelial cells, isolated vessels and organs as well as integrative animal models, trying to identify the underlying mechanisms involved in their actions, to understand their implication in the field of biomedicine. The purpose of the present review is to summarize the most relevant studies to date of AgNPs effects in the cardiovascular system and provide a broader picture of the potential toxic effects and exposure risks, which in turn will allow pointing out the directions of further research as well as new applications of these versatile nanomaterials.

  6. Synthesis of Silver nanoparticles (AgNPs) with Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Campillo Gloria, E.; Ederley, Vélez; Gladis, Morales; César, Hincapié; Jaime, Osorio; Oscar, Arnache; Uribe José, Ignacio; Franklin, Jaramillo

    2017-06-01

    The synthesis of nanomaterials is currently one of the most active in nanoscience branches; especially those help improve the human quality life. Silver nanoparticles (AgNPs) are an example of this as it is known to have inhibitory and bactericidal effects. In this work, we report the synthesis of silver nanoparticles by chemical reduction method of silver nitrate (AgNO3) from aqueous solution, using a mix of polivinyl pyrrolidone (PVP) - Aloe Vera as reducing agent and for stabilization and control of particle size. Silver nanoparticles obtained were characterized by Scanning Electron Microscopy (SEM), UV-visible spectroscopy and measurements using Zetasizer Nano ZS were applied to size estimation. The existence of surface plasmon resonance peak at λmax ~ 420 nm is evidence of silver nanoparticles formation. It was possible to standardize an appropriate protocol for the evaluation of bactericidal activity of the nanoparticles, for mesophilic microorganisms. Bactericidal activity above 90% against these kinds of bacteria was demonstrated.

  7. A perspective of mitochondrial dysfunction in rats treated with silver and titanium nanoparticles (AgNPs and TiNPs).

    PubMed

    Pereira, Lilian Cristina; Pazin, Murilo; Franco-Bernardes, Mariana Furio; Martins, Airton da Cunha; Barcelos, Gustavo Rafael Mazzaron; Pereira, Márcio Cesar; Mesquita, João Paulo; Rodrigues, Jairo Lisboa; Barbosa, Fernando; Dorta, Daniel Junqueira

    2018-05-01

    Nanotechnology is a growing branch of science that deals with the development of structural features bearing at least one dimension in the nano range. More specifically, nanomaterials are defined as objects with dimensions that range from 1 to 100 nm, which give rise to interesting properties. In particular, silver and titanium nanoparticles (AgNPs and TiNPs, respectively) are known for their biological and biomedical properties and are often used in consumer products such as cosmetics, food additives, kitchen utensils, and toys. This situation has increased environmental and occupational exposure to AgNPs and TiNPs, which has placed demand for the risk assessment of NPs. Indeed, the same properties that make nanomaterials so attractive could also prove deleterious to biological systems. Of particular concern is the effect of NPs on mitochondria because these organelles play an essential role in cellular homeostasis. In this scenario, this work aimed to study how AgNPs and TiNPs interact with the mitochondrial respiration chain and to analyze how this interaction interferes in the bioenergetics and oxidative state of the organelles after sub-chronic exposure. Mitochondria were exposed to the NPs by gavage treatment for 21 days to check whether co-exposure of the organelles to the two types of NPs elicited any mitochondrion-NP interaction. More specifically, male Wistar rats were randomly assigned to four groups. Groups I, II, III, and IV received mineral oil, TiNPs (100 μg/kg/day), AgNPs (100 μg/kg/day), and TiNPs + AgNPs (100 μg/kg/day), respectively, by gavage. The liver was immediately removed, and the mitochondria were isolated and used within 3 h. Exposure of mitochondria to TiNPs + AgNPs lowered the respiratory control ratio, causing an uncoupling effect in the oxidative phosphorylation system. Moreover, both types of NPs induced mitochondrial swelling. Extended exposure of mitochondria to the NPs maintained increased ROS levels and

  8. Mimetic Ag nanoparticle/Zn-based MOF nanocomposite (AgNPs@ZnMOF) capped with molecularly imprinted polymer for the selective detection of patulin.

    PubMed

    Bagheri, Nafiseh; Khataee, Alireza; Habibi, Biuck; Hassanzadeh, Javad

    2018-03-01

    Here, Ag nanoparticle/flake-like Zn-based MOF nanocomposite (AgNPs@ZnMOF) with great peroxidase-like activity was applied as an efficient support for molecularly imprinted polymer (MIP) and successfully used for selective determination of patulin. AgNPs@ZnMOF was simply synthesized by creating Ag nanoparticles (Ag NPs) inside the nano-pores of flake-like (Zn)MOF. The high surface area of MOF remarkably improved the catalytic activity of Ag NPs which was assessed by fluorometric, colorimetric and electrochemical techniques. Furthermore, it was observed that patulin could strangely reduce the catalytic activity of AgNPs@ZnMOF, probably due to its electron capturing features. This outcome was the motivation to design an assay for patulin detection. In order to make a selective interaction with patulin molecules, MIP layer was created on the surface of AgNPs@ZnMOF by co-polymerization reaction of 3-aminopropyl triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) monomers wherein patulin was applied as template agent. Combination between the selective identifying feature of MIP and outstanding peroxidase-like activity of novel AgNPs@ZnMOF nanocomposite as well as the sensitive fluorescence detection system was led to the design of a reliable probe for patulin. The prepared MIP-capped AgNPs@ZnMOF catalyzed the H 2 O 2 -terephthalic acid reaction which produced a high florescent product. In the presence of patulin, the fluorescence intensity was decreased proportional to its concentration in the range of 0.1-10µmolL -1 with a detection limit of 0.06µmolL -1 . The proposed method was able to selectively measure patulin in a complex media without significant interfering effects from analogue compounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. The effect of biologically and chemically synthesized silver nanoparticles (AgNPs) on biofilm formation

    NASA Astrophysics Data System (ADS)

    Chojniak, Joanna; Biedroń, Izabela; Mendrek, Barbara; Płaza, Grażyna

    2017-11-01

    Bionanotechnology has emerged up as integration between biotechnology and nanotechnology for developing biosynthetic and environmental-friendly technology for synthesis of nanomaterials. Different types of nanomaterials like copper, zinc, titanium, magnesium, gold, and silver have applied in the various industries but silver nanoparticles have proved to be most effective against bacteria, viruses and eukaryotic microorganisms. The antimicrobial property of silver nanoparticles are widely known. Due to strong antibacterial property silver nanoparticles are used, e.g. in clothing, food industry, sunscreens, cosmetics and many household and environmental appliances. The aim of the study was to compare the effect of silver nanoparticles (AgNPs) synthesized biologically and chemically on the biofilm formation. The biofilm was formed by the bacteria isolated from the water supply network. The commonly used crystal violet assay (CV) was applied for biofilm analysis. In this study effect of biologically synthesized Ag-NPs on the biofilm formation was evaluated.

  10. Study of energy transfer between riboflavin (vitamin B2) and AgNPs

    NASA Astrophysics Data System (ADS)

    Mokashi, Vidya V.; Walekar, Laxman S.; Anbhule, Prashant V.; Lee, Sang Hak; Patil, Shivajirao R.; Kolekar, Govind B.

    2014-03-01

    Here, we report the studies on the interaction and formation of nanobiocomplex between silver nanoparticle (AgNPs) and vitamin B2, i.e., riboflavin (RF). The binding study of AgNP to RF was studied by fluorescence, UV-Vis, and TEM techniques. AgNPs were prepared by reducing AgNO3 with trisodium citrate. Prepared nanoparticles size obtained at 20 nm having surface Plasmon resonance band at 426 nm. The absorbance band of RF at 264, 374, and 444 nm changes significantly in the presence of AgNPs suggests that there is change in the chemical environment surrounding AgNPs. A fluorescence spectral change for a solution of RF upon the addition of AgNPs and rapid quenching is suggestive of a rapid adsorption of RF on AgNPs.

  11. Development of polyethersulfone (PES)/silver nanoparticles (AgNPs)/polyethylene glycol (PEG) nanofiltration membrane

    NASA Astrophysics Data System (ADS)

    Johary, Fasihah; Jamaluddin, Nur Adibah; Rohani, Rosiah; Hassan, Abdul Rahman; Sharifuddin, Syazrin Syima; Isa, Mohd Hafez Mohd

    2018-06-01

    Nanofiltration is a membrane-based separation process that has been used widely in the separation and purification fields for various applications such as dye desalting, applications of water softening, pharmaceuticals and wastewater treatment. In this research, polyethersulfone (PES), polyethylene glycol (PEG), Pluronic F108 and silver nanoparticles (AgNPs) nanofiltration membrane was prepared using casting solution technique with N-methyl-2-pyrrolidone (NMP) was used as a solvent. The effects of Pluronic F108 and silver nanoparticles (AgNPs) concentrations in the casting solutions on the membrane performance/properties were also studied. The membrane pure water permeation (PWP) and salt rejection tests were carried out for membrane performance analysis. Scanning electron microscopy (SEM) was used for the membrane morphology characterization. Fourier transform infrared spectroscopy was utilized to identify functional groups in the membrane. Membrane with 2.0 wt.% of Pluronic F108 and 0.05 wt.% of AgNPs showed the best performances for both PWP (40.89 L/m2h) as well as permeation flux of salts solution of NaCl (43.95 L/m2h), Na2SO4 (21.16 L/m2h), MgCl2 (26.46 L/m2h) and MgSO4 (20.41 L/m2h). All fabricated membranes with different formulation of dope composition obtained high salts rejection in the range of 79% to 91%. SEM images showed addition of AgNPs has improved fabricated membrane morphology with higher pore density and larger macro-void structure.

  12. Influence of salinity on the toxicity of silver nanoparticles (AgNPs) and silver nitrate (AgNO3) in halophilic microalgae, Dunaliella salina.

    PubMed

    Johari, Seyed Ali; Sarkheil, Mehrdad; Behzadi Tayemeh, Mohammad; Veisi, Shakila

    2018-06-13

    This study aim to evaluate the potential toxic effects of citrate coated silver nanoparticles (AgNPs) and ionic silver (AgNO 3 ) on marine microalgae Dunaliella salina under three different salinities (35, 70, and 140 g/L). The toxicity was investigated according to modified OECD guideline (No. 201) by 72 h exposure of microalgae to various concentrations of each of the chemicals in Walne's saline media. According to the results, the growth inhibitory effects of AgNPs and AgNO 3 increased significantly coincidence with increasing time and concentration compared to control (P < 0.05). The values of median inhibitory concentrations (IC 50 ) of AgNPs and AgNO 3 based on average specific growth rate and yield for D. salina increased significantly with elevation of water salinity from 35 to 140 g/L (P < 0.05). Toxicity of AgNO 3 based on IC 50 to D. salina was significantly higher than AgNPs at all salinities (P < 0.05). In conclusion, both AgNPs and AgNO 3 inhibited the growth of D. salina at different saltwater medium. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. The effect of silver nanoparticles (AgNPs) on proliferation and apoptosis of in ovo cultured glioblastoma multiforme (GBM) cells.

    PubMed

    Urbańska, Kaja; Pająk, Beata; Orzechowski, Arkadiusz; Sokołowska, Justyna; Grodzik, Marta; Sawosz, Ewa; Szmidt, Maciej; Sysa, Paweł

    2015-01-01

    Recently, it has been shown that silver nanoparticles (AgNPs) provide a unique approach to the treatment of tumors, especially those of neuroepithelial origin. Thus, the aim of this study was to evaluate the impact of AgNPs on proliferation and activation of the intrinsic apoptotic pathway of glioblastoma multiforme (GBM) cells cultured in an in ovo model. Human GBM cells, line U-87, were placed on chicken embryo chorioallantoic membrane. After 8 days, the tumors were divided into three groups: control (non-treated), treated with colloidal AgNPs (40 μg/ml), and placebo (tumors supplemented with vehicle only). At the end of the experiment, all tumors were isolated. Assessment of cell proliferation and cell apoptosis was estimated by histological, immunohistochemical, and Western blot analyses. The results show that AgNPs can influence GBM growth. AgNPs inhibit proliferation of GBM cells and seem to have proapoptotic properties. Although there were statistically significant differences between control and AgNP groups in the AI and the levels of active caspase 9 and active caspase 3, the level of these proteins in GBM cells treated with AgNPs seems to be on the border between the spontaneous apoptosis and the induced. Our results indicate that the antiproliferative properties of silver nanoparticles overwhelm proapoptotic ones. Further research focused on the cytotoxic effect of AgNPs on tumor and normal cells should be conducted.

  14. Dose-dependent effect of silver nanoparticles (AgNPs) on fertility and survival of Drosophila: An in-vivo study

    PubMed Central

    Raj, Akanksha; Shah, Prasanna

    2017-01-01

    Silver nanoparticles (AgNPs) containing consumer products have been proliferating in the market due to its unique antimicrobial property, however, lack of in-depth knowledge about their potential effect on human health in a longer run is of great concern. Therefore, we investigated dose-dependent in vivo effect of AgNPs using Drosophila as a model system. Drosophila, a genetically tractable organism with distinct developmental stages, short life cycle and significant homology with human serves as an ideal organism to study nanomaterial-mediated toxicity. Our studies suggest that ingestion of AgNPs in Drosophila during adult stage for short and long duration significantly affects egg laying capability along with impaired growth of ovary. Additionally, dietary intake of AgNPs from larval stage has more deleterious effects that result in reduced survival, longevity, ovary size and egg laying capability at a further lower dosage. Interestingly, the trans-generational effect of AgNPs was also observed without feeding progeny with AgNPs, thereby suggesting its impact from previous generation. Our results strongly imply that higher doses of AgNPs and its administration early during development is detrimental to the reproductive health and survival of Drosophila that follows in generations to come without feeding them to AgNPs. PMID:28542630

  15. Dose-dependent effect of silver nanoparticles (AgNPs) on fertility and survival of Drosophila: An in-vivo study.

    PubMed

    Raj, Akanksha; Shah, Prasanna; Agrawal, Namita

    2017-01-01

    Silver nanoparticles (AgNPs) containing consumer products have been proliferating in the market due to its unique antimicrobial property, however, lack of in-depth knowledge about their potential effect on human health in a longer run is of great concern. Therefore, we investigated dose-dependent in vivo effect of AgNPs using Drosophila as a model system. Drosophila, a genetically tractable organism with distinct developmental stages, short life cycle and significant homology with human serves as an ideal organism to study nanomaterial-mediated toxicity. Our studies suggest that ingestion of AgNPs in Drosophila during adult stage for short and long duration significantly affects egg laying capability along with impaired growth of ovary. Additionally, dietary intake of AgNPs from larval stage has more deleterious effects that result in reduced survival, longevity, ovary size and egg laying capability at a further lower dosage. Interestingly, the trans-generational effect of AgNPs was also observed without feeding progeny with AgNPs, thereby suggesting its impact from previous generation. Our results strongly imply that higher doses of AgNPs and its administration early during development is detrimental to the reproductive health and survival of Drosophila that follows in generations to come without feeding them to AgNPs.

  16. Multifunctional AgNPs@Wool: colored, UV-protective and antioxidant functional textiles

    NASA Astrophysics Data System (ADS)

    Shabbir, Mohd; Mohammad, Faqeer

    2018-02-01

    Nanomaterials have great impact on textile industry for multifunctional and smart clothing as per the need of present, and further, green nanotechnology is the current hotspot of research and industrial developments. Silver nanoparticles (AgNPs) are synthesized (in situ) by using natural compounds of plant extracts (naphthoquinones, phenolics/flavonoids, polyphenols) as reducing or stabilizing agents, and simultaneously deposited on wool fabric for coloration, UV protection and antioxidant properties. UV-visible spectroscopy is used to monitor the route of biosynthesis of nanoparticles and transmission electron microscopy for morphological characteristics of synthesized AgNPs. Spherical and almost oval-shaped AgNPs were synthesized by naphthoquinones, polyphenols and flavonoids, respectively. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction pattern (XRD) and Fourier transform infrared spectroscopy were used for the AgNPs@Wool fabrics characterization. SEM-EDX analysis and XRD patterns confirmed the successful deposition of silver nanoparticles on wool. Coloration characteristics in terms of color strength (K/S) and CIEL*a*b*c*h° values, UV protection abilities in terms of UV transmittance and UV protection factor, and % antioxidant activity of AgNPs@Wool are suggestive of good-to-excellent results.

  17. Biochar alleviates the toxicity of imidacloprid and silver nanoparticles (AgNPs) to Enchytraeus albidus (Oligochaeta).

    PubMed

    Nyoka, Ngitheni Winnie-Kate; Kanyile, Sthandiwe Nomthandazo; Bredenhand, Emile; Prinsloo, Godfried Jacob; Voua Otomo, Patricks

    2018-04-01

    The present study investigated the use of biochar for the alleviation of the toxic effects of a nanosilver colloidal dispersion and a chloronicotinyl insecticide. The survival and reproduction of the potworm Enchytraeus albidus were assessed after exposure to imidacloprid and silver nanoparticles (AgNPs). E. albidus was exposed to 0, 25, 50, 100, 200, and 400 mg imidacloprid/kg and 0, 5, 25, 125, and 625 mg Ag/kg for 21 days in 10% biochar amended and non-biochar amended OECD artificial soil. In both exposure substrates, the effects of imidacloprid on survival were significant in the two highest treatments (p < 0.01). No biochar effect was observed as survival was statistically similar in both soils after exposure to imidacloprid. In the case of AgNPs, significant mortality was only observed in the highest AgNP treatments in both the amended and non-amended soils (p < 0.05). Nevertheless, statistically greater survival occurred in the biochar-amended treatment (p < 0.05). Reproduction results showed a more pronounced biochar effect with an EC 50  = 22.27 mg imidacloprid/kg in the non-amended soil and a higher EC 50  = 46.23 mg imidacloprid/kg in the biochar-amended soil. This indicated a 2-fold decrease in imidacloprid toxicity due to biochar amendment. A similar observation was made in the case of AgNPs where a reproduction EC 50  = 166.70 mg Ag/kg soil in the non-amended soil increased to an EC 50  > 625 mg Ag/kg soil (the highest AgNP treatment) in the amended soil. This indicated at least a 3.7-fold decrease in AgNPs toxicity due to biochar amendment. Although more studies may be needed to optimize the easing effects of biochar on the toxicity of these chemicals, the present results show that biochar could be useful for the alleviation of the toxic effects of imidacloprid and silver nanoparticles in the soil.

  18. Rapid visual detection of quaternary ammonium surfactants using citrate-capped silver nanoparticles (Ag NPs) based on hydrophobic effect.

    PubMed

    Zheng, Li-Qing; Yu, Xiao-Dong; Xu, Jing-Juan; Chen, Hong-Yuan

    2014-01-01

    In this work, a rapid, sensitive and low-cost colorimetric method for detection of quaternary ammonium surfactants using citrate-capped silver nanoparticles (Ag NPs) was developed. The quaternary ammonium surfactants induce the aggregation of Ag NPs through the hydrophobic effect, which is a novel aggregation mechanism of Ag NPs. The addition of cationic surfactant results in color change of Ag NPs solution from yellow to red and finally to colorless, which is due to the broadening of the surface plasmon band. The color change was monitored using a UV-vis spectrophotometer. The LOD of different cationic surfactants was in the range of 0.5-5 µM. More importantly, this detection method was successfully utilized to the disinfectant residual sample. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

  19. Promising biocidal activity of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) as anti-infective agents against perilous pathogens.

    PubMed

    Manukumar, H M; Umesha, S; Kumar, H N Naveen

    2017-09-01

    The advent of biodegradable polymer-encapsulated drug nanoparticles has made an exciting area of drug delivery research. The present study investigated novel and simple route for synthesis of thymol loaded chitosan silver nanoparticles (T-C@AgNPs) using chitosan and thymol as reducing, capping agent respectively to understand the therapeutic efficacy. The UV-vis spectroscopy, DLS, FT-IR, SEM, EDS, XRD used for characterization and radical scavenging activity, anti-microbial and biocompatibility was taken to ascertain an efficacy of novel T-C@AgNPs. The T-C@AgNPs intense peak at 490nm indicates the formation of nanoparticles and had average particle size of 28.94nm with spherical shape, monodisperse state in water, also exhibited excellent biocompatibility of cubic shaped pure silver element containing T-C@AgNPs. The antibacterial activity was studied for gram positive and gram negative food-borne pathogens and effective inhibition at 100μgmL -1 to S. aureus, S. epidermidis, S. haemolyticus (10.08, 10.00, 11.23mm) and S. typhimurium, P. aeruginosa and S. flexneri (9.28, 9.33, 12.03mm) compared to antibiotic Streptomycin. This study revealed the efficacy against multiple food-borne pathogens and therapeutic efficacy of T-C@AgNPs offers a valuable contribution in the area of nanotechnology. This proved to be a first-class novel antimicrobial material for the first time in this study. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Silver nanoparticles (AgNPs) as a contrast agent for imaging of animal tissue using swept-source optical coherence tomography (SSOCT)

    NASA Astrophysics Data System (ADS)

    Mondal, Indranil; Raj, Shipra; Roy, Poulomi; Poddar, Raju

    2018-01-01

    We present noninvasive three-dimensional depth-resolved imaging of animal tissue with a swept-source optical coherence tomography system at 1064 nm center wavelength and silver nanoparticles (AgNPs) as a potential contrast agent. A swept-source laser light source is used to enable an imaging rate of 100 kHz (100 000 A-scans s-1). Swept-source optical coherence tomography is a new variant of the optical coherence tomography (OCT) technique, offering unique advantages in terms of sensitivity, reduction of motion artifacts, etc. To enhance the contrast of an OCT image, AgNPs are utilized as an exogeneous contrast agent. AgNPs are synthesized using a modified Tollens method and characterization is done by UV-vis spectroscopy, dynamic light scattering, scanning electron microscopy and energy dispersive x-ray spectroscopy. In vitro imaging of chicken breast tissue, with and without the application of AgNPs, is performed. The effect of AgNPs is studied with different exposure times. A mathematical model is also built to calculate changes in the local scattering coefficient of tissue from OCT images. A quantitative estimation of scattering coefficient and contrast is performed for tissues with and without application of AgNPs. Significant improvement in contrast and increase in scattering coefficient with time is observed.

  1. Enhanced wound healing activity of Ag-ZnO composite NPs in Wistar Albino rats.

    PubMed

    Kantipudi, Sravani; Sunkara, Jhansi Rani; Rallabhandi, Muralikrishna; Thonangi, Chandi Vishala; Cholla, Raga Deepthi; Kollu, Pratap; Parvathaneni, Madhu Kiran; Pammi, Sri Venkata Narayana

    2018-06-01

    In the present study, silver (Ag) and Ag-zinc oxide (ZnO) composite nanoparticles (NPs) were synthesised and studied their wound-healing efficacy on rat model. Ultraviolet-visible spectroscopy of AgNPs displayed an intense surface plasmon (SP) resonance absorption at 450 nm. After the addition of aqueous Zn acetate solution, SP resonance band has shown at 413.2 nm indicating a distinct blue shift of about 37 nm. X-ray diffraction analysis Ag-ZnO composite NPs displayed existence of two mixed sets of diffraction peaks, i.e. both Ag and ZnO, whereas AgNPs exhibited face-centred cubic structures of metallic Ag. Scanning electron microscope (EM) and transmission EM analyses of Ag-ZnO composite NPs revealed the morphology to be monodispersed hexagonal and quasi-hexagonal NPs with distribution of particle size of 20-40 nm. Furthermore, the authors investigated the wound-healing properties of Ag-ZnO composite NPs in an animal model and found that rapid healing within 10 days when compared with pure AgNPs and standard drug dermazin.

  2. Photoconversion of 4-nitrophenol in the presence of hydrazine with AgNPs-TiO2 nanoparticles prepared by the sol-gel method.

    PubMed

    Hernández-Gordillo, Agileo; Arroyo, Missael; Zanella, R; Rodríguez-González, V

    2014-03-15

    The photocatalytic properties of functionalized TiO2 with silver nanoparticles (AgNPs) for the conversion of 4-nitrophenol to 4-aminophenol in the presence of hydrazine were investigated. The TiO2 semiconductor synthesized by the sol-gel method was functionalized with AgNPs at different loadings, and their structural and optical properties were characterized by several techniques. The functionalized TiO2 with 1.5wt% AgNPs presented the highest photocatalytic activity for the conversion of 4-nitrophenol with appropriate hydrazine concentrations (0.5M). The photoefficiency enhancement under UV light irradiation was attributed to the electron transfer from the TiO2 semiconductor surface to the adsorbed acceptor reactant (4-nitrophenol) through the deposited AgNPs. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Halloysite Nanotubes Supported Ag and ZnO Nanoparticles with Synergistically Enhanced Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Shu, Zhan; Zhang, Yi; Yang, Qian; Yang, Huaming

    2017-02-01

    Novel antimicrobial nanocomposite incorporating halloysite nanotubes (HNTs) and silver (Ag) into zinc oxide (ZnO) nanoparticles is prepared by integrating HNTs and decorating Ag nanoparticles. ZnO nanoparticles (ZnO NPs) and Ag nanoparticles (Ag NPs) with a size of about 100 and 8 nm, respectively, are dispersively anchored onto HNTs. The synergistic effects of ZnO NPs, Ag NPs, and HNTs led to the superior antibacterial activity of the Ag-ZnO/HNTs antibacterial nanocomposites. HNTs facilitated the dispersion and stability of ZnO NPs and brought them in close contact with bacteria, while Ag NPs could promote the separation of photogenerated electron-hole pairs and enhanced the antibacterial activity of ZnO NPs. The close contact with cell membrane enabled the nanoparticles to produce the increased concentration of reactive oxygen species and the metal ions to permeate into the cytoplasm, thus induced quick death of bacteria, indicating that Ag-ZnO/HNTs antibacterial nanocomposite is a promising candidate in the antibacterial fields.

  4. Effect of AgCl NPs: Physical, thermal, absorption and luminescence properties

    NASA Astrophysics Data System (ADS)

    Nurhafizah, H.; Rohani, M. S.

    2017-06-01

    Silver nanoparticles (AgCl NPs) are embedded in Er3+/Nd3+ co-doped lithium niobate tellurite glasses of the form (68-x)TeO2-15Li2CO3-15Nb2O5-1Er2O3-1Nd2O3-(x)AgCl with x = 1,2 and 3 mol% via conventional melt-quenching technique. The physical properties such as density, ionic packing density, refractive index and electronic polarizability are computed utilizing the usual method. The existence of AgCl NPs with an average size of 3.7 nm is confirmed using TEM analysis. Moreover, the thermal stability and Hruby criterion of the glass decreases as the AgCl NPs content increases. The direct optical band gap are found decrease as the AgCl NPs content increase, but both indirect optical band gap and Urbach energy are found increases as AgCl NPs content increases. The luminescence spectra shows two strong emission which is the purple emission at 436 nm and red emission at 724 nm which also been observed has strong quenching due to the AgCl NPs, Er3+/Nd3+ dopant and modifier, lithium niobate which possessed magnetic penetration. These glass compositions may be potential for various applications such as solid state devices including laser.

  5. Effect of chemically and biologically synthesized Ag nanoparticles on the algae growth inhibition

    NASA Astrophysics Data System (ADS)

    Anna, Mražiková; Oksana, Velgosová; Jana, Kavuličová

    2017-12-01

    Over the past few years green methods for preparation of silver nanoparticles has become necessary due to its friendly influence on ecosystem. In the present work antimicrobial properties of biologically synthesized silver nanoparticles (Bio-AgNPs) using green algae extract and chemically synthesized silver nanoparticles (Chem-AgNPs) using sodium citrate against algae Parachlorella kessleri is investigated. Both used Bio-AgNPs and Chem-AgNPs exhibit long-term stability as demonstrated by UV-vis spectroscopy measurements. The results revealed stronger toxic effects of Bio-AgNPs on agar plates what was confirmed clear inhibition zone around wells impregnated with Bio-AgNPs. On the other hand Bio-AgNPs were confirmed to be less toxic in aquatic environments for the growths of green algae P. kessleri comparing to Chem-AgNPs.

  6. Biosynthesis and Characterization of AgNPs-Silk/PVA Film for Potential Packaging Application.

    PubMed

    Tao, Gang; Cai, Rui; Wang, Yejing; Song, Kai; Guo, Pengchao; Zhao, Ping; Zuo, Hua; He, Huawei

    2017-06-17

    Bionanocomposite packaging materials have a bright future for a broad range of applications in the food and biomedical industries. Antimicrobial packaging is one of the bionanocomposite packaging materials. Silver nanoparticle (AgNP) is one of the most attractive antimicrobial agents for its broad spectrum of antimicrobial activity against microorganisms. However, the traditional method of preparing AgNPs-functionalized packaging material is cumbersome and not environmentally friendly. To develop an efficient and convenient biosynthesis method to prepare AgNPs-modified bionanocomposite material for packaging applications, we synthesized AgNPs in situ in a silk fibroin solution via the reduction of Ag⁺ by the tyrosine residue of fibroin, and then prepared AgNPs-silk/poly(vinyl alcohol) (PVA) composite film by blending with PVA. AgNPs were synthesized evenly on the surface or embedded in the interior of silk/PVA film. The prepared AgNPs-silk/PVA film exhibited excellent mechanical performance and stability, as well as good antibacterial activity against both Gram-negative and Gram-positive bacteria. AgNPs-silk/PVA film offers more choices to be potentially applied in the active packaging field.

  7. The impact of anticancer activity upon Beta vulgaris extract mediated biosynthesized silver nanoparticles (ag-NPs) against human breast (MCF-7), lung (A549) and pharynx (Hep-2) cancer cell lines.

    PubMed

    Venugopal, K; Ahmad, H; Manikandan, E; Thanigai Arul, K; Kavitha, K; Moodley, M K; Rajagopal, K; Balabhaskar, R; Bhaskar, M

    2017-08-01

    The present study tried for a phyto-synthetic method of producing silver nanoparticles (Ag-NPs) with size controlled as and eco-friendly route that can lead to their advanced production with decorative tranquil morphology. By inducing temperature fluctuation of the reaction mixture from 25 to 80°C the plasmon resonance band raised slowly which had an ultimate effect on size and shape of Ag-NPs as shown by UV-visible spectroscopy and TEM results. The biosynthesized nanoparticles showed good cytotoxic impact against MCF-7, A549 and Hep2 cells compared to normal cell lines. Compared to control plates, the percentage of cell growth inhibition was found to be high with as concentrations of Ag-NPs becomes more as determined by MTT assay. The AO/EtBr staining observations demonstrated that the mechanism of cell death induced by Ag-NPs was due to apoptosis in cancer cells. These present results propose that the silver nanoparticles (Ag-NPs) may be utilized as anticancer agents for the treatment of various cancer types. However, there is a need for study of in vivo examination of these nanoparticles to find their role and mechanism inside human body. Further, studies we plan to do biomarker fabrication from the green synthesized plant extract nanoparticles like silver, gold and copper nanoparticles with optimized shape and sizes and their enhancement of these noble nanoparticles. Copyright © 2017. Published by Elsevier B.V.

  8. Effect of cysteine and humic acids on bioavailability of Ag from Ag nanoparticles to a freshwater snail

    USGS Publications Warehouse

    Luoma, Samuel N.; Tasha Stoiber,; Croteau, Marie-Noele; Isabelle Romer,; Ruth Merrifeild,; Lead, Jamie

    2016-01-01

    Metal-based engineered nanoparticles (NPs) will undergo transformations that will affect their bioavailability, toxicity and ecological risk when released to the environment, including interactions with dissolved organic material. The purpose of this paper is to determine how interactions with two different types of organic material affect the bioavailability of silver nanoparticles (AgNPs). Silver uptake rates by the pond snail Lymnaea stagnalis were determined after exposure to 25 nmol l-1 of Ag as PVP AgNPs, PEG AgNPs or AgNO3, in the presence of either Suwannee River humic acid or cysteine, a high-affinity thiol-rich organic ligand. Total uptake rate of Ag from the two NPs was either increased or not strongly affected in the presence of 1 – 10 mg 1-1 humic acid. Humic substances contain relatively few strong ligands for Ag explaining their limited effects on Ag uptake rate. In contrast, Ag uptake rate was substantially reduced by cysteine. Three components of uptake from the AgNPs were quantified in the presence of cysteine using a biodynamic modeling approach: uptake of dissolved Ag released by the AgNPs, uptake of a polymer or large (>3kD) Ag-cysteine complex and uptake of the nanoparticle itself. Addition of 1:1 Ag:cysteine reduced concentrations of dissolved Ag, which contributed to, but did not fully explain the reductions in uptake. A bioavailable Ag-cysteine complex (> 3kD) appeared to be the dominant avenue of uptake from both PVP AgNPs and PEG AgNPs in the presence of cysteine. Quantifying the different avenues of uptake sets the stage for studies to assess toxicity unique to NPs.

  9. Aggregation-based colorimetric sensor for determination of prothioconazole fungicide using colloidal silver nanoparticles (AgNPs)

    NASA Astrophysics Data System (ADS)

    Ivrigh, Zahra Jafar-Nezhad; Fahimi-Kashani, Nafiseh; Hormozi-Nezhad, M. Reza

    2017-12-01

    There is a growing interest in developing high-performance sensors monitoring fungicides, due to their broadly usage and their adverse effects on humans and wildlife. In the present study, a colorimetric probe has been proposed for detection of prothioconazole based on aggregation of unmodified silver nanoparticles (AgNPs). Under optimized condition, linear relationships between the concentration of prothioconazole and the absorbance ratio of A500/A395 were found over the range of 0.01 μg·mL- 1 to 0.4 μg·mL- 1 with quantification limit as low as 1.7 ng·mL- 1. Furthermore, AgNPs color change from yellow to pink-orange in presence of prothioconazole, indicates highly sensitive naked-eye colorimetric assay for quantifying prothioconazole in real applications. The proposed approach was successfully used for the determination of prothioconazole in wheat flour and paddy water sample.

  10. Rapid Biosynthesis of AgNPs Using Soil Bacterium Azotobacter vinelandii With Promising Antioxidant and Antibacterial Activities for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Karunakaran, Gopalu; Jagathambal, Matheswaran; Gusev, Alexander; Torres, Juan Antonio Lopez; Kolesnikov, Evgeny; Kuznetsov, Denis

    2017-07-01

    Silver nanoparticles (AgNPs) are applied in various fields from electronics to biomedical applications as a result of their high surface-to-volume ratio. Even though different approaches are available for synthesis of AgNPs, a nontoxic method for the synthesis has not yet been developed. Thus, this study focused on developing an easy and ecofriendly approach to synthesize AgNPs using Azotobacter vinelandii culture extracts. The biosynthesized nanoparticles were further characterized by ultraviolet-visible (UV-Vis) spectroscopy, x-ray diffraction (XRD), Fourier transform infrared (FTIR), energy-dispersive spectrum, particle size distribution (PSD), and transmission electron microscopy (TEM). UV absorption noticed at 435 nm showed formation of AgNPs. The XRD pattern showed a face-centered cubic structure with broad peaks of 28.2°, 32.6°, 46.6°, 55.2°, 57.9°, and 67.8°. The FTIR confirmed the involvement of various functional groups in the biosynthesis of AgNPs. The PSD and TEM analyses showed spherical, well-distributed nanoparticles with an average size of 20-70 nm. The elemental studies confirmed the existence of pure AgNPs. The bacterial extract containing extracellular enzyme nitrate reductase converted silver nitrate into AgNPs. AgNPs significantly inhibited the growth of pathogenic bacteria such as Streptomyces fradiae (National Collection of Industrial Microorganisms (NCIM) 2419), Staphylococcus aureus (NCIM 2127), Escherichia coli (NCIM 2065), and Serratia marcescens (NCIM 2919). In addition, biosynthesized AgNPs were found to possess strong antioxidant activity. Thus, the results of this study revealed that biosynthesized AgNPs could serve as a lead in the development of nanomedicine.

  11. Loading Ag nanoparticles on Cd(II) boron imidazolate framework for photocatalysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Min; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002; Zhang, De-Xiang

    2016-05-15

    An amine-functionalized Cd(II) boron imidazolate framework (BIF-77) with three-dimensional open structure has been successfully synthesized, which can load Ag nanoparticles (NPs) for photocatalytic degradation of methylene blue (MB). - Graphical abstract: An amine-functionalized neutral Cd(II) boron imidazolate framework can load Ag NPs and show excellent photocatalytic degradation behavious for MB. - Highlights: • Amine-functionalization. • Neutral boron imidazolate framework. • Loading Ag nanoparticles (NPs). • Photocatalytic degradation of methylene blue.

  12. Preparation and antibacterial performance testing of Ag nanoparticles embedded biological materials

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyun; Gao, Guanhui; Sun, Chengjun; Zhu, Yaoyao; Qu, Lingyun; Jiang, Fenghua; Ding, Haibing

    2015-03-01

    In this study, we developed an environmentally friendly chemistry strategy to synthesize Ag nanoparticles (Ag-NPs) embedded biological material, powdered mussel shell (PMS). With the PMS as scaffolds and surfactant, Ag nanoparticles of controllable size dispersed uniformly on it via liquid chemical reduction approach. Morphologies and characteristics of synthesized Ag-NPs/PMS hybrids were analyzed with TEM, SEM and XPS. Antibacterial properties were investigated with Gram-positive bacteria (Arthrobacter sulfureus (A. sulfureus) YACS14, Staphylococcus aureus (S. aureus)) and Gram-negative bacteria (Vibrio anguillarum (V. anguillarum) MVM425, Escherichia coli (E. coli)). The antimicrobial results illustrated that Ag-NPs/PMS composites have antibacterial effect on both sea water and fresh water bacteria with a better effect on sea water bacteria. The degree of antibacterial effect is directly related to the amount of Ag released from Ag-NPs/PMS.

  13. A biodynamic understanding of dietborne and waterborne Ag uptake from Ag NPs in the sediment-dwelling oligochaete, Tubifex tubifex

    USGS Publications Warehouse

    Tangaa, Stine Rosendal; Winther-Nielsen, Margrethe; Selck, Henriette; Croteau, Marie-Noele

    2018-01-01

    Metal nanoparticles (Me-NPs) are increasingly used in various products, such as inks and cosmetics, enhancing the likelihood of their release into aquatic environments. An understanding of the mechanisms controlling their bioaccumulation and ecotoxicity in aquatic biota will help support environmental risk assessment. Here we characterized unidirectional parameters for uptake and elimination of silver (Ag) in the sediment-dwelling oligochaete Tubifex tubifex after waterborne (0.01–47 nmol Ag/L) and dietborne (0.4–482 nmol Ag/g dw sed.) exposures to Ag NPs and AgNO3, respectively. Worms accumulated Ag from AgNO3more efficiently than from Ag NPs during waterborne exposure. The Ag uptake rate constants from water were 8.2 L/g/d for AgNO3 and 0.34 L/g/d for Ag NPs. Silver accumulated from both forms was efficiently retained in tissues, as no significant loss of Ag was detected after up to 20 days of depuration in clean media. High mortality (~50%) during depuration (i.e. after 17 days) was only observed for worms exposed to waterborne AgNO3 (3 nmol/L). Sediment exposures to both Ag forms resulted in low accumulation, i.e., the uptake rate constants were 0.002 and 0.005 g/g/d for AgNO3 and Ag NPs, respectively. Avoidance was only observed for worms exposed to sediment amended with AgNO3. Incorporation of the estimated rate constants into a biodynamic model predicted that sediment is likely the most important route of uptake for Ag in both forms in ecologically relevant aquatic environments. However, inference of bioavailability from our estimations of Ag assimilation efficiencies (AE) suggests that Ag (AE: 3–12% for AgNO3 and 0.1–0.8% for Ag NPs) is weakly bioavailable from sediment for this species. Thus, Ag amended to sediment as NPs might not pose greater problems than 'conventional' Ag for benthic organisms such as T. tubifex.

  14. Effect of toxicity of Ag nanoparticles on SERS spectral variance of bacteria

    NASA Astrophysics Data System (ADS)

    Cui, Li; Chen, Shaode; Zhang, Kaisong

    2015-02-01

    Ag nanoparticles (NPs) have been extensively utilized in surface-enhanced Raman scattering (SERS) spectroscopy for bacterial identification. However, Ag NPs are toxic to bacteria. Whether such toxicity can affect SERS features of bacteria and interfere with bacterial identification is still unknown and needed to explore. Here, by carrying out a comparative study on non-toxic Au NPs with that on toxic Ag NPs, we investigated the influence of nanoparticle concentration and incubation time on bacterial SERS spectral variance, both of which were demonstrated to be closely related to the toxicity of Ag NPs. Sensitive spectral alterations were observed on Ag NPs with increase of NPs concentration or incubation time, accompanied with an obvious decrease in number of viable bacteria. In contrast, SERS spectra and viable bacterial number on Au NPs were rather constant under the same conditions. A further analysis on spectral changes demonstrated that it was cell response (i.e. metabolic activity or death) to the toxicity of Ag NPs causing spectral variance. However, biochemical responses to the toxicity of Ag were very different in different bacteria, indicating the complex toxic mechanism of Ag NPs. Ag NPs are toxic to a great variety of organisms, including bacteria, fungi, algae, protozoa etc., therefore, this work will be helpful in guiding the future application of SERS technique in various complex biological systems.

  15. Synthesis of silver nanoparticles (Ag NPs) for anticancer activities (MCF 7 breast and A549 lung cell lines) of the crude extract of Syzygium aromaticum.

    PubMed

    Venugopal, K; Rather, H A; Rajagopal, K; Shanthi, M P; Sheriff, K; Illiyas, M; Rather, R A; Manikandan, E; Uvarajan, S; Bhaskar, M; Maaza, M

    2017-02-01

    In the present report, silver nanoparticles were synthesized using Piper nigrum extract for in vitro cytotoxicity efficacy against MCF-7 and HEP-2 cells. The silver nanoparticles (AgNPs) were formed within 20min and after preliminarily confirmation by UV-Visible spectroscopy (strong peak observed at ~441nm), they were characterized by using FT-IR and HR-TEM. The TEM images show spherical shape of biosynthesized AgNPs with particle size in the range 5-40nm while as compositional analysis were observed by EDAX. MTT assays were carried out for cytotoxicity of various concentrations of biosynthesized silver nanoparticles and Piper nigrum extract ranging from 10 to 100μg. The biosynthesized silver nanoparticles showed a significant anticancer activity against both MCF-7 and Hep-2 cells compared to Piper nigrum extract which was dose dependent. Our study thus revealed an excellent application of greenly synthesized silver nanoparticles using Piper nigrum. The study further suggested the potential therapeutic use of these nanoparticles in cancer study. Copyright © 2016. Published by Elsevier B.V.

  16. Comparative effects on rat primary astrocytes and C6 rat glioma cells cultures after 24-h exposure to silver nanoparticles (AgNPs)

    NASA Astrophysics Data System (ADS)

    Salazar-García, Samuel; Silva-Ramírez, Ana Sonia; Ramirez-Lee, Manuel A.; Rosas-Hernandez, Hector; Rangel-López, Edgar; Castillo, Claudia G.; Santamaría, Abel; Martinez-Castañon, Gabriel A.; Gonzalez, Carmen

    2015-11-01

    The aim of this work was to compare the effects of 24-h exposure of rat primary astrocytes and C6 rat glioma cells to 7.8 nm AgNPs. Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor and current treatments lead to diverse side-effects; for this reason, it is imperative to investigate new approaches, including those alternatives provided by nanotechnology, like nanomaterials (NMs) such as silver nanoparticles. Herein, we found that C6 rat glioma cells, but no primary astrocytes, decreased cell viability after AgNPs treatment; however, both cell types diminished their proliferation. The decrease of glioma C6 cells proliferation was related with necrosis, while in primary astrocytes, the decreased proliferation was associated with the induction of apoptosis. The ionic control (AgNO3) exerted a different profile than AgNPs; the bulk form did not modify the basal effect in each determination, whereas cisplatin, a well-known antitumoral drug used as a comparative control, promoted cytotoxicity in both cell types at specific concentrations. Our findings prompt the need to determine the fine molecular and cellular mechanisms involved in the differential biological responses to AgNPs in order to develop new tools or alternatives based on nanotechnology that may contribute to the understanding, impact and use of NMs in specific targets, like glioblastoma cells.

  17. Hollow Au-Ag Nanoparticles Labeled Immunochromatography Strip for Highly Sensitive Detection of Clenbuterol

    NASA Astrophysics Data System (ADS)

    Wang, Jingyun; Zhang, Lei; Huang, Youju; Dandapat, Anirban; Dai, Liwei; Zhang, Ganggang; Lu, Xuefei; Zhang, Jiawei; Lai, Weihua; Chen, Tao

    2017-01-01

    The probe materials play a significant role in improving the detection efficiency and sensitivity of lateral-flow immunochromatographic test strip (ICTS). Unlike conventional ICTS assay usually uses single-component, solid gold nanoparticles as labeled probes, in our present study, a bimetallic, hollow Au-Ag nanoparticles (NPs) labeled ICTS was successfully developed for the detection of clenbuterol (CLE). The hollow Au-Ag NPs with different Au/Ag mole ratio and tunable size were synthesized by varying the volume ratio of [HAuCl4]:[Ag NPs] via the galvanic replacement reaction. The surface of hollow Ag-Au NPs was functionalized with 11-mercaptoundecanoic acid (MUA) for further covalently bonded with anti-CLE monoclonal antibody. Overall size of the Au-Ag NPs, size of the holes within individual NPs and also Au/Ag mole ratio have been systematically optimized to amplify both the visual inspection signals and the quantitative data. The sensitivity of optimized hollow Au-Ag NPs probes has been achieved even as low as 2 ppb in a short time (within 15 min), which is superior over the detection performance of conventional test strip using Au NPs. The optimized hollow Au-Ag NPs labeled test strip can be used as an ideal candidate for the rapid screening of CLE in food samples.

  18. Organic memory capacitor device fabricated with Ag nanoparticles.

    PubMed

    Kim, Yo-Han; Jung, Sung Mok; Hu, Quanli; Kim, Yong-Sang; Yoon, Tae-Sik; Lee, Hyun Ho

    2011-07-01

    In this study, it is demonstrated that an organic memory structure using pentacene and citrate-stabilized silver nanoparticles (Ag NPs) as charge storage elements on dielectric SiO2 layer and silicon substrate. The Ag NPs were synthesized by thermal reduction method of silver trifluoroacetate with oleic acid. The synthesized Ag NPs were analyzed with high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) for their crystalline structure. The capacitance versus voltage (C-V) curves obtained for the Ag NPs embedded capacitor exhibited flat-band voltage shifts, which demonstrated the presence of charge storages. The citrate-capping of the Ag NPs was confirmed by ultraviolet-visible (UV-VIS) and Fourier transformed infrared (FTIR) spectroscopy. With voltage sweeping of +/-7 V, a hysteresis loop having flatband voltage shift of 7.1 V was obtained. The hysteresis loop showed a counter-clockwise direction. In addition, electrical performance test for charge storage showed more than 10,000 second charge retention time. The device with Ag NPs can be applied to an organic memory device for flexible electronics.

  19. Antimicrobial kinetics of Alstonia scholaris bark extract-mediated AgNPs

    NASA Astrophysics Data System (ADS)

    Supraja, N.; Prasad, T. N. V. K. V.; David, E.; Giridhara Krishna, T.

    2016-06-01

    Nanobiotechnology is considered as one of the important branches of nanotechnology, and research on synthesis of nanoscale materials, silver in particular, using plant and plant parts has been progressing rapidly. Herein, we used bark extract of Alstonia scholaris one of the most important medicinal plants to synthesize silver nanoparticles (AgNPs) which exhibited excellent antimicrobial properties against biofilm formed in drinking water PVC pipes. The biosynthesis of silver nanoparticles was done by treating 90 mL of 1 mM AgNO3 aqueous solution with 10 mL of 5 % bark extract. As-prepared silver nanoparticles were characterized using the biophysical techniques such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, and dynamic light scattering for the measurement of hydrodynamic diameter and zeta potential. The kinetics of the antimicrobial activity against PVC biofilm of prepared silver nanoparticles were done using comparative solution suspension time-killing assessments and which are evidenced in Epi-fluorescent microscopic observations.

  20. Influence of silver content on rifampicin adsorptivity for magnetite/Ag/rifampicin nanoparticles

    NASA Astrophysics Data System (ADS)

    Ivashchenko, Olena; Coy, Emerson; Peplinska, Barbara; Jarek, Marcin; Lewandowski, Mikołaj; Załęski, Karol; Warowicka, Alicja; Wozniak, Anna; Babutina, Tatiana; Jurga-Stopa, Justyna; Dolinsek, Janez; Jurga, Stefan

    2017-02-01

    Magnetite nanoparticles (NPs) decorated with silver (magnetite/Ag) are intensively investigated due to their application in the biomedical field. We demonstrate that the increase of silver content on the surface of nanoparticles improves the adsorptivity of antibiotic rifampicin as well as antibacterial properties. The use of ginger extract allowed to improve the silver nucleation on the magnetite surface that resulted in an increase of silver content. Physicochemical and functional characterization of magnetite/Ag NPs was performed. Our results show that 5%-10% of silver content in magnetite/Ag NPs is already sufficient for antimicrobial properties against Streptococcus salivarius and Staphylococcus aureus. The rifampicin molecules on the magnetite/Ag NPs surface made the spectrum of antimicrobial activity wider. Cytotoxicity evaluation of the magnetite/Ag/rifampicin NPs showed no harmful action towards normal human fibroblasts, whereas the effect on human embryonic kidney cell viability was time and dose dependent.

  1. Limitations and possibilities of green synthesis and long-term stability of colloidal Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Velgosová, Oksana; Mražíková, Anna

    2017-12-01

    In this paper the influence of algae life cycle and the solutions pH on the green synthesis of colloidal Ag nanoparticles (AgNPs) as well as effect of different storage conditions on AgNPs long-term stability was investigated. Silver nanoparticles were biologically synthesized using extracts of Parachlorella kessleri algae cultivated 1, 2, 3 and 4 weeks. The formation of AgNPs was monitored using a UV-vis spectrophotometer and verified by TEM observation. The results confirmed formation of polyhedron and/or near polyhedron AgNPs, ranging between 5 and 60 nm in diameter. The age of algae influenced the synthesis rate and an amount of AgNPs in solution. The best results were obtained using tree weeks old algae. UV-vis analysis and TEM observation also revealed that the size and the stability of AgNPs depend on the pH of solution. AgNPs formed in solutions of higher pH (8 and 10) are polyhedron, fine, with narrow size interval and stabile. Nanoparticles formed in solutions of low pH (2, 4 and 6) started to lose their stability on 10th day of experiment, and the particle size interval was wide. The long-term stability of AgNPs can be influenced by light and temperature conditions. The most significant stability loss was observed at day light and room temperature (21°C). After 200-days significant amount of agglomerated particles settled on the bottom of the Erlenmeyer flask. AgNPs stored at dark and room temperature showed better long-term stability, weak particles agglomeration was observed. AgNPs stored at dark and at temperature 5°C showed the best long-term stability. Such AgNPs remained spherical, fine (5-20 nm), with narrow size interval and stable (no agglomeration) even after more than six months.

  2. High-performance SERS substrate based on hybrid structure of graphene oxide/AgNPs/Cu film@pyramid Si

    PubMed Central

    Li, Zhe; Xu, Shi Cai; Zhang, Chao; Liu, Xiao Yun; Gao, Sai Sai; Hu, Li Tao; Guo, Jia; Ma, Yong; Jiang, Shou Zhen; Si, Hai Peng

    2016-01-01

    We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays (GO/AgNPs/PCu@Si) by a low-cost and simple method. The GO/AgNPs/PCu@Si substrate presents high sensitivity, good homogeneity and well stability with R6G molecules as a probe. The detected concentration of Rhodamine 6 G (R6G) is as low as 10−15 M. These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software, the electric field enhancement is not only formed between the AgNPs, but also formed between the AgNPs and Cu film. And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue (MB) and crystal violet (CV). This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine, food safety and biotechnology. PMID:27924863

  3. High-performance SERS substrate based on hybrid structure of graphene oxide/AgNPs/Cu film@pyramid Si

    NASA Astrophysics Data System (ADS)

    Li, Zhe; Xu, Shi Cai; Zhang, Chao; Liu, Xiao Yun; Gao, Sai Sai; Hu, Li Tao; Guo, Jia; Ma, Yong; Jiang, Shou Zhen; Si, Hai Peng

    2016-12-01

    We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays (GO/AgNPs/PCu@Si) by a low-cost and simple method. The GO/AgNPs/PCu@Si substrate presents high sensitivity, good homogeneity and well stability with R6G molecules as a probe. The detected concentration of Rhodamine 6 G (R6G) is as low as 10-15 M. These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software, the electric field enhancement is not only formed between the AgNPs, but also formed between the AgNPs and Cu film. And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue (MB) and crystal violet (CV). This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine, food safety and biotechnology.

  4. High-performance SERS substrate based on hybrid structure of graphene oxide/AgNPs/Cu film@pyramid Si.

    PubMed

    Li, Zhe; Xu, Shi Cai; Zhang, Chao; Liu, Xiao Yun; Gao, Sai Sai; Hu, Li Tao; Guo, Jia; Ma, Yong; Jiang, Shou Zhen; Si, Hai Peng

    2016-12-07

    We present a novel surface-enhanced Raman scattering (SERS) substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays (GO/AgNPs/PCu@Si) by a low-cost and simple method. The GO/AgNPs/PCu@Si substrate presents high sensitivity, good homogeneity and well stability with R6G molecules as a probe. The detected concentration of Rhodamine 6 G (R6G) is as low as 10 -15 M. These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software, the electric field enhancement is not only formed between the AgNPs, but also formed between the AgNPs and Cu film. And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue (MB) and crystal violet (CV). This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine, food safety and biotechnology.

  5. Plumbago auriculata leaf extract-mediated AgNPs and its activities as antioxidant, anti-TB and dye degrading agents.

    PubMed

    Jaryal, Neeraj; Kaur, Harpreet

    2017-11-01

    In the present work, silver nanoparticles have been biosynthesized by utilizing the alcoholic extract of Plumbago auriculata. The optimization of reaction conditions was carried out by monitoring the reactions with the help of UV-Visible absorption spectroscopy. The characterization of AgNP was carried out by infrared spectroscopy, transmission electron microscopy and X-Ray diffraction (XRD) studies. The biogenic AgNPs were tested against Mycobacterium tuberculosis using Microplate Almar Blue assay (MABA) and their antioxidant activity was also evaluated. The silver nanoparticles were also assessed for their reducing activity against organic dyes. The AgNPs were spherical in shape with size ranging from 15 to 45 nm with face centered cubic geometry as revealed by XRD analysis. The AgNPs possessed good antitubercular activity with MIC value of 1.6 μg/ml and these also exhibited promising antioxidant activity with IC 50 value of 28.2. Furthermore, AgNPs also reduced congo red within 2 h and malachite green was degraded within 40 min. The present work demonstrated the utilization of P. auriculata for biosynthesis of AgNP which could be a potential candidate for antitubercular drug development and it could also be used as an antioxidant agent. The application of AgNP in reducing agent can be further extended and evaluated for purification of effluent water from textile industries.

  6. Synthesis of Ag-NPs impregnated cellulose composite material: its possible role in wound healing and photocatalysis.

    PubMed

    Ali, Attarad; Haq, Ihsan Ul; Akhtar, Javeed; Sher, Muhammad; Ahmed, Naveed; Zia, Muhammad

    2017-06-01

    Cellulose is the natural biopolymer normally used as supporting agent with enhanced applicability and properties. In present study, cellulose isolated from citrus waste is used for silver nanoparticles (Ag-NPs) impregnation by a simple and reproducible method. The Ag-NPs fabricated cellulose (Ag-Cel) was characterised by powder X-rays diffraction, Fortier transform infrared spectroscopy and scanning electron microscopy. The thermal stability was studied by thermo-gravimetric analysis. The antibacterial activity performed by disc diffusion assay reveals good zone of inhibition against Staphylococcus aureus and Escherichia coli by Ag-Cel as compared Ag-NPs. The discs also displayed more than 90% reduction of S. aureus culture in broth within 150 min. The Ag-Cel discs also demonstrated minor 2,2-diphenyl 1-picryl-hydrazyl radical scavenging activity and total reducing power ability while moderate total antioxidant potential was observed. Ag-Cel effectively degrades methylene-blue dye up to 63.16% under sunlight irradiation in limited exposure time of 60 min. The Ag-NPs impregnated cellulose can be effectively used in wound dressing to prevent bacterial attack and scavenger of free radicals at wound site, and also as filters for bioremediation and wastewater purification.

  7. Synthesis, kinetics and photocatalytic study of "ultra-small" Ag-NPs obtained by a green chemistry method using an extract of Rosa 'Andeli' double delight petals.

    PubMed

    Suárez-Cerda, Javier; Alonso-Nuñez, Gabriel; Espinoza-Gómez, Heriberto; Flores-López, Lucía Z

    2015-11-15

    This paper reports the effect of different concentrations of Rosa 'Andeli' double delight petals aqueous extract (PERA) in the synthesis of silver nanoparticles (Ag-NPs), using an easy green chemistry method. Its kinetics study and photocatalytic activity were also evaluated. The Ag-NPs were obtained using an aqueous silver nitrate solution (AgNO3) with 9.66% w/v, 7.25% w/v, and 4.20% w/v PERA as both reducing-stabilizing agent. The formation of the Ag-NPs was demonstrated by analysis of UV-vis spectroscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). TEM analysis shows spherical nanoparticles in shape and size between ∼0.5 and 1.4nm. A comparative study was done to determine which concentration was the best reducing-stabilizing agent, and we found out that "ultra-small" nanoparticles (0.5-1.1nm) were obtained with 9.66% w/v of PERA. The size of the Ag-NPs depends on the concentration of PERA and Ag(I). The reaction of formation of "ultra-small" Ag-NPs, proved to be first order for metallic precursor (silver) and second order for reducing-stabilizing agent (PERA). The Ag-NPs showed photocatalytic activity, in degradation of commercial dye with an efficiency of 95%. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Facile and eco-friendly fabrication of AgNPs coated silk for antibacterial and antioxidant textiles using honeysuckle extract.

    PubMed

    Zhou, Yuyang; Tang, Ren-Cheng

    2018-01-01

    Recently, there is a growing trend towards the functionalization of silk through nanotechnology for the prevention of fiber damage from microbial attack and the enhancement of hygienic aspects. Considering sustainable development and environmental protection, the eco-friendly fabrication of silver nanoparticles (AgNPs)-modified silk using natural extracts has currently become a hot research area. This study presents a facile strategy for the fabrication of colorful and multifunctional silk fabric using biogenic AgNPs prepared by honeysuckle extract as natural reductant and stabilizing agents. The influences of pH and reactant concentrations on the AgNPs synthesis were investigated. The color characteristics and functionalities of AgNPs treated silk were evaluated. The results revealed that the particle size of AgNPs decreased with increasing pH. The diameter of AgNPs decreased with increasing amount of honeysuckle extract and reducing amount of silver nitrate. The transmission electron microscopy image showed that the AgNPs were spherical in shape with a narrow size distribution. The treated silk showed excellent antibacterial activities against E. coli and S. aureus, and certain antioxidant activity. Both of the antibacterial and antioxidant activities were well maintained even after 30 washing cycles. This work provides a sustainable and eco-friendly approach to the fabrication of AgNPs coated silk for colorful and long-term multifunctional textiles using honeysuckle extract. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Synthesis and characterization of PVK/AgNPs nanocomposites prepared by laser ablation.

    PubMed

    Abd El-Kader, F H; Hakeem, N A; Elashmawi, I S; Menazea, A A

    2015-03-05

    Nanocomposites of Poly (n-vinylcarbazole) PVK/Ag nanoparticles were prepared by laser ablation of a silver plate in aqueous solution of chlorobenzene. The influences of laser parameters such as; time of irradiation, source power and wavelength (photon energy) on structural, morphological and optical properties have been investigated using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet-visible (UV-Vis) and Photoluminescence (PL). A correlation between the investigated properties has been discussed. XRD, TEM and PL indicated that the complexation between AgNPs and PVK in the composite system is possible. Only the reflection peak at 2θ=38° of AgNPs appeared in the composite nanoparticles while the other reflection peaks were destroyed. The nanoparticles shape and size distribution were evaluated from TEM images. TEM analysis revealed a lower average particle size at long laser irradiation time 40min and short laser wavelength 532nm together with high laser power 570mW. From UV-Visible spectra the values of absorption coefficient, absorption edge and energy tail were calculated. The reduction of band tail value with increasing the laser ablation parameters confirms the decrease of the disorder in such composite system. The PL and UV-Vis. spectra confirm that nanocomposite samples showed quantum confinement effect. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Strong damping of the localized surface plasmon resonance of Ag nanoparticles by Ag2O.

    PubMed

    Wu, Qingmen; Si, Mengting; Zhang, Bing; Zhang, Kang; Li, Huanhuan; Mi, Longfei; Jiang, Yang; Rong, Yan; Chen, Junling; Fang, Yingcui

    2018-07-20

    By studying oxidation of AgNPs (Ag nanoparticles) and decomposition of the produced silver oxide, we demonstrate that the localized surface plasmon resonance (LSPR) of AgNPs was damped by Ag 2 O produced during oxygen plasma irradiation (OPI). The AgNPs were fabricated by evaporation of high pure silver under high vacuum. The oxidation was conducted in oxygen plasma generated by radio frequency glow discharging in vacuum, and the decomposition was performed by annealing the silver oxide in nitrogen ambient at temperatures ranging from room temperature to 450 °C. Samples were characterized by color, absorption spectra, surface enhanced Raman scattering, x-ray photoelectron spectroscopy, and field emission scanning electron microscopy. The bandgap of the silver oxide was calculated. We propose that AgNPs are only partially oxidized into silver oxide during OPI, and the LSPR of the AgNPs left without being oxidation is strongly damped by the produced silver oxide. This LSPR damping is responsible for the transparency of the sample after OPI for 2 s.

  11. Strong damping of the localized surface plasmon resonance of Ag nanoparticles by Ag2O

    NASA Astrophysics Data System (ADS)

    Wu, Qingmen; Si, Mengting; Zhang, Bing; Zhang, Kang; Li, Huanhuan; Mi, Longfei; Jiang, Yang; Rong, Yan; Chen, Junling; Fang, Yingcui

    2018-07-01

    By studying oxidation of AgNPs (Ag nanoparticles) and decomposition of the produced silver oxide, we demonstrate that the localized surface plasmon resonance (LSPR) of AgNPs was damped by Ag2O produced during oxygen plasma irradiation (OPI). The AgNPs were fabricated by evaporation of high pure silver under high vacuum. The oxidation was conducted in oxygen plasma generated by radio frequency glow discharging in vacuum, and the decomposition was performed by annealing the silver oxide in nitrogen ambient at temperatures ranging from room temperature to 450 °C. Samples were characterized by color, absorption spectra, surface enhanced Raman scattering, x-ray photoelectron spectroscopy, and field emission scanning electron microscopy. The bandgap of the silver oxide was calculated. We propose that AgNPs are only partially oxidized into silver oxide during OPI, and the LSPR of the AgNPs left without being oxidation is strongly damped by the produced silver oxide. This LSPR damping is responsible for the transparency of the sample after OPI for 2 s.

  12. Antimicrobial activity of tantalum oxide coatings decorated with Ag nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cao, Huiliang, E-mail: hlc@mail.sic.ac.cn; Meng, Fanhao; Liu, Xuanyong, E-mail: xyliu@mail.sic.ac.cn

    Silver plasma immersion ion implantation was used to decorate silver nanoparticles (Ag NPs) on tantalum oxide (TO) coatings. The coatings acted against bacterial cells (Staphylococcus epidermidis) in the dark by disrupting their integrity. The action was independent of silver release and likely driven by the electron storage capability of the Schottky barriers established at the interfaces between Ag NPs and the TO support. Moreover, no apparent side effect on the adhesion and differentiation of rat bone mesenchymal stem cells was detected when using Ag NPs-modified TO coatings. These results demonstrate that decoration of tantalum oxide using Ag NPs could bemore » a promising procedure for improving the antibacterial properties for orthopedic and dental implants.« less

  13. Silver nanoparticles (AgNPs) biosynthesized using pod extract of Cola nitida enhances antioxidant activity and phytochemical composition of Amaranthus caudatus Linn

    NASA Astrophysics Data System (ADS)

    Azeez, Luqmon; Lateef, Agbaje; Adebisi, Segun A.

    2017-02-01

    This study investigates the influence of different concentrations of AgNPs biologically synthesized using pod extract of Cola nitida on antioxidant activity, phenolic contents, flavonoid contents and compositions of Amaranthus caudatus L. AgNPs of 25, 50, 75, 100 and 150 ppm were utilized in growing A. caudatus while water was used as control. Delayed germination for two days was observed for A. caudatus grown with 150 ppm of AgNPs, while others showed no difference. There were 43.3, 38.7, 26.7 and 6.48% improvements in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant activity of A. caudatus grown with 25, 50, 75 and 100 ppm of AgNPs, respectively, compared to control. Antioxidant activity of A. caudatus grown with AgNPs reduced with increase in the concentrations of AgNPs. A. caudatus grown with 50 ppm of AgNPs was the most potent with the least IC50 of 0.67 mg/ml. Significant improvements obtained for phenolic and flavonoid contents grown with AgNPs were concentration dependent. Enhancements of 21.9, 68.19, and 1.98% in phenolic contents were achieved in treatments with 25, 50 and 75 ppm AgNPs, respectively, while 32.58, 35.80, and 7.20% improvement in flavonoids were obtained for 25, 50 and 100 ppm treatments, respectively. Kaempferol and quercetin were the most abundant flavonoids in A. caudatus treated with 50 ppm of AgNPs, showing the highest flavonoid composition. This further confirms A. caudatus grown with 50 ppm of AgNPs as the most potent. This study has shown that concentration-dependent AgNPs can be used to boost antioxidant activity and phytochemical contents of vegetables.

  14. Bio-inspired sustainable and green synthesis of plasmonic Ag/AgCl nanoparticles for enhanced degradation of organic compound from aqueous phase.

    PubMed

    Devi, Th Babita; Ahmaruzzaman, M

    2016-09-01

    In the current study, we report the utilization of the biogenic potential of Benincasa hispida (ash gourd) peel extract for the synthesis of Ag embedded AgCl nanoparticles nanoparticles (Ag/AgCl NPs) without the use of any external organic solvents. The appearance of dark brown color from the pale yellow color confirmed the formation of Ag/AgCl nanoparticles which was further validated by absorbance peak using UV-visible spectroscopy. The phytochemicals (flavones) present in the B. hispida peel extract acts as a reducing/stabilizing agents. The morphology and size of the synthesized NPs were characterized by transmission electron microscope (TEM), selected area electron microscope (SAED) and high resolution transmission electron microscope (HR-TEM). FT-IR spectra of the B. hispida peel extract and after the development of nanoparticles are determined to identify the functional groups responsible for the conversion of metal ions to metal nanoparticles. The synthesized nanoparticles showed an excellent photocatalytic property in the degradation of toxic dye like malachite green oxalate under sunlight irradiation. For the first time, malachite green oxalate dye was degraded by Ag/AgCl nanoparticles under sunlight irradiation.

  15. Development of HA/Ag-NPs Composite Coating from Green Process for Hip Applications.

    PubMed

    Lozoya-Rodríguez, Denisse A; de Lima, Renata; Fraceto, Leonardo F; Ledezma Pérez, Antonio; Bazaldua Domínguez, Mercedes; Gómez Batres, Roberto; Reyes Rojas, Armando; Orozco Carmona, Víctor

    2017-08-08

    In the present study, biological hydroxyapatite (HA) was obtained from bovine bones through a thermal process. A total of 0% and 1% of silver nanoparticles (Ag-NPs) synthesized from Opuntia ficus (nopal) were added to the biological hydroxyapatite coatings using an atmospheric plasma spray (APS) on a Ti6Al4V substrate. Following this, its antimicrobial efficiency was evaluated against the following bacterial strains: Escherichia coli , Staphylococcus aureus , and Pseudomonas aeruginosa . This was conducted according to the Japanese Industrial Standard (JIS) Z2801:2000 "Antimicrobial Product-Test for Antimicrobial Activity and Efficacy". Scanning electron microscopy (SEM) showed that the silver nanoparticles (Ag-NPs) were evenly distributed on the coating surface. Energy dispersive X-ray spectroscopy (EDX) shows that apatite deposition occurs on a daily basis, maintaining a Ca/P rate between 2.12 and 1.45. Biocompatibility properties were evaluated with osteoblast-like cells (MC3T3-E1) by single-cell gel electrophoresis assay and Tali image cytometry.

  16. Preparation of SiO2@Ag Composite Nanoparticles and Their Antimicrobial Activity.

    PubMed

    Qin, Rui; Li, Guian; Pan, Liping; Han, Qingyan; Sun, Yan; He, Qiao

    2017-04-01

    At normal atmospheric temperature, the modified sol–gel method was employed to synthesize SiO2 nanospheres (SiO2 NSs) whose average size was about 352 nm. Silver nanoparticles (Ag NPs) were uniformly distributed on the surface of SiO2 nanospheres (SiO2 NSs) by applying chemical reduction method at 95 °C and the size of silver nanoparticles (Ag NPs) could be controlled by simply tuning the reaction time and the concentration of sodium citrate. Besides, the size, morphology, structure and optical absorption properties of SiO2@Ag composite nanoparticles were measured and characterized by laser particle size analyzer (LPSA), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) and ultraviolet visible absorption spectrometer (UV-Vis), respectively. Furthermore, antimicrobial effect experiments that against gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus) were carried out to characterize the antibacterial activity of synthesized SiO2@Ag composite nanoparticles. The results show that the prepared SiO2@Ag composite nanoparticles have strong antimicrobial activity, which is associated with the size of silver nanoparticles.

  17. Revelation of susceptibility differences due to Hg(II) accumulation in Streptococcus pyogenes against CX-AgNPs and Cefixime by atomic force microscopy.

    PubMed

    Rasheed, Wasia; Shah, Muhammad Raza; Perveen, Samina; Ahmed, Shakil; Uzzaman, Sami

    2018-01-01

    Solution based method for the formation of chemically modified silver nanoparticles (CX-AgNPs) using Cefixime as stabilizing and reducing agent was developed. The CX-AgNPs were characterized by AFM, UV-visible, FT-IR and MALDI-TOF MS. Bactericidal efficiency of CX-AgNPs and Cefixime against Streptococcus pyogenes was evaluated. Afterwards, susceptibility differences of Streptococcus pyogenes due to accumulation of Hg(II) against CX-AgNPs and Cefixime were estimated and validated through Atomic force microscopy. Selectivity and sensitivity of CX-AgNPs against Hg(II) was evaluated in a systematic manner. The CX-AgNPs was titrated against optically silent Hg(II) which induced enhancement in the SPR band of CX-AgNPs. The increase in intensity of SPR band of CX-AgNPs was determined to be proportionate to the concentration of Hg(II) in the range of 33.3-700µM obeying linear regression equation of y = 0.125x + 8.962 with the detection limit of 0.10µM and the coefficient of determination equals to 0.985 (n = 3). The association constant Ka of CX-AgNPs-Hg(II) was found to be 386.0095mol -1 dm 3 by using the Benesi Hildebrand plot. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Enhancement of Ag nanoparticles concentration by prior ion implantation

    NASA Astrophysics Data System (ADS)

    Mu, Xiaoyu; Wang, Jun; Liu, Changlong

    2017-09-01

    Thermally grown SiO2 layer on Si substrates were singly or sequentially implanted with Zn or Cu and Ag ions at the same fluence of 2 × 1016/cm2. The profiles of implanted species, structure, and spatial distribution of the formed nanoparticles (NPs) have been characterized by the cross-sectional transmission electron microscope (XTEM) and Rutherford backscattering spectrometry (RBS). It is found that pre-implantation of Zn or Cu ions could suppress the self sputtering of Ag atoms during post Ag ion implantation, which gives rise to fabrication of Ag NPs with a high density. Moreover, it has also been demonstrated that the suppressing effect strongly depends on the applied energy and mobility of pre-implanted ions. The possible mechanism for the enhanced Ag NPs concentration has been discussed in combination with SRIM simulations. Both vacancy-like defects acting as the increased nucleation sites for Ag NPs and a high diffusivity of prior implanted ions in SiO2 play key roles in enhancing the deposition of Ag implants.

  19. Rapid colorimetric sensing of gadolinium by EGCG-derived AgNPs: the development of a nanohybrid bioimaging probe.

    PubMed

    Singh, Rohit Kumar; Mishra, Sourav; Jena, Satyapriya; Panigrahi, Bijayananda; Das, Bhaskar; Jayabalan, Rasu; Parhi, Pankaj Kumar; Mandal, Dindyal

    2018-04-17

    Polyphenol functionalized silver nanoparticles (AgNPs) have been developed and demonstrated as colorimetric sensors for the selective detection of gadolinium. The newly obtained AgNP-Gd3+ conjugates exhibit high aqueous dispersibility and excitation dependent fluorescence emission. The conjugates offer multicolor bioimaging potential owing to their excellent luminescence properties.

  20. Synthesis of novel cellulose- based antibacterial composites of Ag nanoparticles@ metal-organic frameworks@ carboxymethylated fibers.

    PubMed

    Duan, Chao; Meng, Jingru; Wang, Xinqi; Meng, Xin; Sun, Xiaole; Xu, Yongjian; Zhao, Wei; Ni, Yonghao

    2018-08-01

    A novel cellulose-based antibacterial material, namely silver nanoparticles@ metal-organic frameworks@ carboxymethylated fibers composites (Ag NPs@ HKUST-1@ CFs), was synthesized. The results showed that the metal-organic frameworks (HKUST-1) were uniformly anchored on the fiber's surfaces by virtue of complexation between copper ions in HKUST-1 and carboxyl groups on the carboxymethylated fibers (CFs). The silver nanoparticles (Ag NPs) were immobilized and well-dispersed into the pores and/or onto the surfaces of HKUST-1 via in situ microwave reduction, resulting in the formation of novel Ag NPs@ HKUST-1@ CFs composites. The antibacterial assays showed that the as-prepared composites exhibited a much higher antibacterial activity than Ag NPs@ CFs or HKUST-1@ CFs samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Monocrystalline solar cells performance coated by silver nanoparticles: Effect of NPs sizes from point of view Mie theory

    NASA Astrophysics Data System (ADS)

    Elnoby, Rasha M.; Mourad, M. Hussein; Elnaby, Salah L. Hassab; Abou Kana, Maram T. H.

    2018-05-01

    Solar based cells coated by nanoparticles (NPs) acknowledge potential utilizing as a part of photovoltaic innovation. The acquired silicon solar cells (Si-SCs) coated with different sizes of silver nanoparticles (Ag NPs) as well as uncoated were fabricated in our lab. The sizes and optical properties of prepared NPs were characterized by spectroscopic techniques and Mie theory respectively. The reflectivity of Si-SCs showed reduction of this property as the size of NPs increased. Electrical properties as open circuit current, fill factor and output power density were assessed and discussed depending on point of view of Mie theory for the optical properties of NPs. Also, photostabilities of SCs were assessed using diode laser of wavelength 450 nm and power 300 mW. Coated SCs with the largest Ag NPs size showed the highest Photostability due to its highest scattering efficiency according to Mie theory concept.

  2. Succinic acid functionalized silver nanoparticles (Suc-Ag NPs) for colorimetric sensing of melamine

    NASA Astrophysics Data System (ADS)

    Rajar, Kausar; Sirajuddin; Balouch, Aamna; Bhanger, M. I.; Shah, Muhammad Tariq; Shaikh, Tayyaba; Siddiqui, Samia

    2018-03-01

    In this study, a quantitative colorimetric sensing strategy is developed for the rapid, sensitive and selective determination of melamine. The sensing system relies on the application of succinic acid as a selective recognition probe functionalized over Ag NPs. The synthesized Ag NPs were modified with cysteamine to induce positively charged atmosphere which allowed easy and favorable functionalization of succinic acid. The di-carboxyl nature of succinic acid enabled its binding to both cysteamine and melamine. The strong and favorable linkage between succinic acids carbonyl and amine moieties of melamine triggered aggregation of silver NPs producing a significant shift in the measured absorption excitation. This change in the excitation along with the colorimetric response was found linearly proportional to the melamine concentration in the range of 0.1-1.2 μM. The developed sensor system is simple and unlike electrostatic attraction based sensor system utilize selective linkage for the recognition of melamine. In addition to this, the developed optical probe can efficiently be used for the determination of melamine in milk samples.

  3. Hydrodynamic chromatography coupled to single-particle ICP-MS for the simultaneous characterization of AgNPs and determination of dissolved Ag in plasma and blood of burn patients.

    PubMed

    Roman, Marco; Rigo, Chiara; Castillo-Michel, Hiram; Munivrana, Ivan; Vindigni, Vincenzo; Mičetić, Ivan; Benetti, Federico; Manodori, Laura; Cairns, Warren R L

    2016-07-01

    Silver nanoparticles (AgNPs) are increasingly used in medical devices as innovative antibacterial agents, but no data are currently available on their chemical transformations and fate in vivo in the human body, particularly on their potential to reach the circulatory system. To study the processes involving AgNPs in human plasma and blood, we developed an analytical method based on hydrodynamic chromatography (HDC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) in single-particle detection mode. An innovative algorithm was implemented to deconvolute the signals of dissolved Ag and AgNPs and to extrapolate a multiparametric characterization of the particles in the same chromatogram. From a single injection, the method provides the concentration of dissolved Ag and the distribution of AgNPs in terms of hydrodynamic diameter, mass-derived diameter, number and mass concentration. This analytical approach is robust and suitable to study quantitatively the dynamics and kinetics of AgNPs in complex biological fluids, including processes such as agglomeration, dissolution and formation of protein coronas. The method was applied to study the transformations of AgNP standards and an AgNP-coated dressing in human plasma, supported by micro X-ray fluorescence (μXRF) and micro X-ray absorption near-edge spectroscopy (μXANES) speciation analysis and imaging, and to investigate, for the first time, the possible presence of AgNPs in the blood of three burn patients treated with the same dressing. Together with our previous studies, the results strongly support the hypothesis that the systemic mobilization of the metal after topical administration of AgNPs is driven by their dissolution in situ. Graphical Abstract Simplified scheme of the combined analytical approach adopted for studying the chemical dynamics of AgNPs in human plasma/blood.

  4. Reactive oxygen species acts as executor in radiation enhancement and autophagy inducing by AgNPs.

    PubMed

    Wu, Hao; Lin, Jun; Liu, Peidang; Huang, Zhihai; Zhao, Peng; Jin, Haizhen; Ma, Jun; Wen, Longping; Gu, Ning

    2016-09-01

    Malignant glioma is one of the most common intracranial tumor with a dismal prognosis. The radiosensitizing effect of silver nanoparticles (AgNPs) on glioma both in vitro and in vivo were demonstrated in the previous studies of our group. However, the underlying mechanism is still unclear. In this present study, the use of antioxidants is employed for the regulating of reactive oxygen species (ROS) in U251 cells treated with various agents, and the results shows that ROS played an essential role in the autophagy inducing and radiosensitization effect of AgNPs. Moreover, the inhibition of protective autophagy with 3-MA is another way to increase ROS, resulting in the increasing of cell death and apoptosis. Taken together, understanding the relationship between the elevated ROS and autophagy and the effect of ROS should be useful to the clinical applications of AgNPs. These findings could potentially be exploited for new therapeutic strategies in glioma radiotherapy. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Chromatographic analysis of phytochemicals components present in mangifera indica leaves for the synthesis of silver nanoparticles by AgNO3 reduction

    NASA Astrophysics Data System (ADS)

    Martínez-Bernett, D.; Silva-Granados, A.; Correa-Torres, S. N.; Herrera, A.

    2016-02-01

    It was studied the green synthesis of silver nanoparticles (AgNPs) from the reduction of a silver nitrate solution (1 and 10mM) in the presence of an extract of mangifera indica leaves. Phytochemicals components present in extracts of mango leaves were determined using a GC-MS chromatograph. The results showed the presence of the phenolic compound pyrogallol (26.9% wt/5mL of extract) and oleic acid (29.1% wt/5mL of extract), which are useful for the reduction of the metallic salt AgNO3 and the stabilization of silver nanoparticles. The synthesized nanoparticles were characterized by UV visible spectroscopy (UV-vis), evidencing absorbances at wavelengths of 417nm (AgNPs-1) and 414nm (AgNPs- 10), which are characteristic peaks of this metallic nanoparticles. Scanning Electron Microscopy (SEM) was used to determine the size of the synthesized nanoparticles. A particle size of about 28±7nm was observed for the AgNPs-1 sample and 26±5nm for the AgNPs-10. This suggests the advantages of green chemistry to obtain silver nanoparticles with a narrow size distribution.

  6. Antitumor Activity of Alloy and Core-Shell-Type Bimetallic AgAu Nanoparticles

    NASA Astrophysics Data System (ADS)

    Shmarakov, Igor; Mukha, Iuliia; Vityuk, Nadiia; Borschovetska, Vira; Zhyshchynska, Nelya; Grodzyuk, Galyna; Eremenko, Anna

    2017-05-01

    Nanoparticles (NPs) of noble metals, namely gold and silver, remain promising anticancer agents capable of enhancing current surgery- and chemotherapeutic-based approaches in cancer treatment. Bimetallic AgAu composition can be used as a more effective agent due to the synergetic effect. Among the physicochemical parameters affecting gold and silver nanoparticle biological activity, a primary concern relates to their size, shape, composition, charge, etc. However, the impact of metal components/composition as well as metal topological distribution within NPs is incompletely characterized and remains to be further elucidated and clarified. In the present work, we tested a series of colloidal solutions of AgAu NPs of alloy and core-shell type for an antitumor activity depending on metal molar ratios (Ag:Au = 1:1; 1:3; 3:1) and topological distribution of gold and silver within NPs (AucoreAgshell; AgcoreAushell). The efficacy at which an administration of the gold and silver NPs inhibits mouse Lewis lung carcinoma (LLC) growth in vivo was compared. The data suggest that in vivo antitumor activity of the studied NPs strongly depends on gold and silver interaction arising from their ordered topological distribution. NPs with Ag core covered by Au shell were the most effective among the NPs tested towards LLC tumor growth and metastasizing inhibition. Our data show that among the NPs tested in this study, AgcoreAushell NPs may serve as a suitable anticancerous prototype.

  7. Biosynthesis of AgNPs using Carica Papaya peel extract and evaluation of its antioxidant and antimicrobial activities.

    PubMed

    Kokila, T; Ramesh, P S; Geetha, D

    2016-12-01

    Waste fruit peel mediated synthesis of silver nanoparticles (AgNPs) is a green chemistry approach that links nanotechnology and biotechnology. Using biological medium such as peel extract for the biosynthesis of nanoparticles is an ecofriendly and emerging scientific trend. With this back drop the present study focused on the biosynthesis of AgNPs using Carica Papaya peel extract (CPPE) and evaluation of its antimicrobial potentials of the nanoparticles against different human pathogens and to investigate the free radical scavenging activity. Water soluble antioxidant constituents present in Carica Papaya peel extract were mainly responsible for the reduction of silver ions to nanosized Ag particles. UV-vis spectral analysis shows surface plasmon resonance band at 430nm. The presence of active proteins and phenolic groups present in the biomass before and after reduction was identified by Fourier transform infrared spectroscopy. X-ray diffraction study shows the average size of the silver nanoparticles is in the range of 28nm, as well as revealed their face centered cubic structure. Atomic force microscope image gives the 3D topological characteristic of silver nanoparticles and the particle size ranges from 10 to 30nm. The average particle size distribution of silver nanoparticles is 161nm (Dynamic light scattering) and the corresponding average zeta potential value is -20.5mV, suggesting higher stability of silver nanoparticles. Biologically synthesized nanoparticles efficiently inhibited pathogenic organisms both gram-positive and gram-negative bacteria. The biosynthesized nanoparticles might serve as a potent antioxidant as revealed by DPPH and ABT S+ assay. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Preparation and antibacterial activities of Ag/Ag+/Ag3+ nanoparticle composites made by pomegranate (Punica granatum) rind extract

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Ren, Yan-yu; Wang, Tao; Wang, Chuang

    Nano-silver and its composite materials are widely used in medicine, food and other industries due to their strong conductivity, size effect and other special performances. So far, more microbial researches have been applied, but a plant method is rarely reported. In order to open up a new way to prepare AgNP composites, pomegranate peel extract was used in this work to reduce Ag+ to prepare Ag/Ag+/Ag3+ nanoparticle composites. UV-Vis was employed to detect and track the reduction of Ag+ and the forming process of AgNPs. The composition, structure and size of the crystal were analyzed by XRD and TEM. Results showed that, under mild conditions, pomegranate peel extract reacted with dilute AgNO3 solution to produce Ag/Ag+/Ag3+ nanoparticle composites. At pH = 8 and 10 mmol/L of AgNO3 concentration, the size of the achieved composites ranged between 15 and 35 nm with spherical shapes and good crystallinity. The bactericidal experiment indicated that the prepared Ag/Ag+/Ag3+ nanoparticles had strong antibacterial activity against gram positive bacteria and gram negative bacteria. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the newly synthesized Ag/Ag+/Ag3+ nanoparticles. This provided a useful clue to further study the AgNP biosynthesis mechanism.

  9. An eco-benign synthesis of AgNPs using aqueous extract of Longan fruit peel: Antiproliferative response against human breast cancer cell line MCF-7, antioxidant and photocatalytic deprivation of methylene blue.

    PubMed

    Khan, Arif Ullah; Yuan, Qipeng; Khan, Zia Ul Haq; Ahmad, Aftab; Khan, Faheem Ullah; Tahir, Kamran; Shakeel, Muhammad; Ullah, Sadeeq

    2018-05-07

    Plants mediated synthesis of noble metal nanoparticles is encountered as a clean, environment friendly, lucrative and benign loom. The current study consists of clean and green synthesis of Silver nanoparticles (AgNPs). Phytoconstituents from Longan (Euphorbia longana Lam.) fruit peel were used to reduce Ag + into AgNPs. Different analytical techniques i.e. UV-vis Spectroscopy, X-ray diffraction spectroscopy (XRD), electron dispersive X-ray (EDX), High-resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) were used to analyze the synthesized AgNPs. AgNPs have localized surface plasmon resonance (LSPR) peak at 445 nm which is confirmed by UV-vis spectroscopy. HRTEM showed that the prepared AgNPs are spheroid in shape and well dispersed while XRD results showed that the AgNPs are face centered cubic crystalline. EDX confirmed the elemental composition of AgNPs. The antiproliferative response of AgNPs was assayed by an exhaustive MTT assay. AgNPs showed potent anticancer activity (88%) against breast cancer cells MCF-7. Moreover, the green produced AgNPs effectively scavenged 91% of the stable and harmful 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical which confirms its' efficient antioxidant nature. AgNPs have profound photocatalytic degradation (99%) of methylene blue in a short period of time (7 min). The noteworthy biological and photocatalytic responses of the green and cleanly produced AgNPs are encountered to their well dispersion, petite volume and round shaped structure. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Picosecond laser fabricated Ag, Au and Ag-Au nanoparticles for detecting ammonium perchlorate using a portable Raman spectrometer

    NASA Astrophysics Data System (ADS)

    Byram, Chandu; Moram, Sree Sathya Bharathi; Soma, Venugopal Rao

    2018-04-01

    In this paper, we present the results from fabrication studies of Ag, Au, and Ag-Au alloy nanoparticles (NPs) using picosecond laser ablation technique in the presence of liquid media. The alloy formation in the NPs was confirmed from UV-Visible measurements. The shape and crystallinity of NPs were investigated by using high resolution transmission electron microscopy (HRTEM), selected area diffraction pattern (SAED) and energy dispersive spectroscopy (EDS). The SERS effect of fabricated NPs was tested with methylene blue and an explosive molecule (ammonium perchlorate) using a portable Raman spectrometer and achieved EFs of ˜106.

  11. Fabrication of high aspect ratio nanogrid transparent electrodes via capillary assembly of Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, Juhoon; Park, Chang-Goo; Lee, Su-Han; Cho, Changsoon; Choi, Dae-Geun; Lee, Jung-Yong

    2016-05-01

    In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq-1 and an optical transmittance of 85.4%.In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq-1 and an optical transmittance of 85.4%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01896c

  12. Tailoring the light absorption of Ag-PZT thin films by controlling the growth of hexagonal- and cubic-phase Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Hu, Tao; Wang, Zongrong; Ma, Ning; Du, Piyi

    2017-12-01

    PbZr0.52Ti0.48O3 thin films containing hexagonal and cubic Ag nanoparticles (Ag NPs) of various sizes were prepared using the sol-gel technique. During the aging process, Ag ions were photo-reduced to form hexagonal Ag NPs. These NPs were uniform in size, and their uniformity was maintained in the thin films during the heat treatment process. Both the total volume and average size of the hexagonal Ag NPs increased with an increasing Ag ion concentration from 0.02 to 0.08 mol l-1. Meanwhile, the remaining Ag ions were reduced to form unstable Ag-Pb alloy particles with Pb ions during the early heating stage. During subsequent heat treatment, these alloys decomposed to form cubic Ag NPs in the thin films. The absorption range of the thin films, quantified as the full width at half maximum in the ultraviolet-visible absorption spectrum, expanded from 6.3 × 1013 Hz (390-425 nm) to 8.4 × 1013 Hz (383-429 nm) as the Ag NPs/PZT ratio increased from 0.2 to 0.8. This work provides an effective way to broaden the absorption range and enhance the optical properties of such films.

  13. Synthesis of silver nanoparticles by solar irradiation of cell-free Bacillus amyloliquefaciens extracts and AgNO3.

    PubMed

    Wei, Xuetuan; Luo, Mingfang; Li, Wei; Yang, Liangrong; Liang, Xiangfeng; Xu, Lin; Kong, Peng; Liu, Huizhou

    2012-01-01

    Silver nanoparticles (AgNPs) were obtained by solar irradiation of cell-free extracts of Bacillusamyloliquefaciens and AgNO3. Light intensity, extract concentration, and NaCl addition influenced the synthesis of AgNPs. Under optimized conditions (solar intensity 70,000 lx, extract concentration 3 mg/mL, and NaCl content 2 mM), 98.23±0.06% of the Ag+ (1 mM) was reduced to AgNPs within 80 min, and the ζ-potential of AgNPs reached -70.84±0.66 mV. TEM (Transmission electron microscopy) and XRD (X-ray diffraction) analysis confirmed that circular and triangular crystalline AgNPs with mean diameter of 14.6 nm were synthesized. Since heat-inactivated extracts also mediated the formation of AgNPs, enzymatic reactions are likely not involved in AgNPs formation. A high absolute ζ-potential value of the AgNPs, possibly caused by interaction with proteins likely explains the high stability of AgNPs suspensions. AgNPs showed antimicrobial activity against Bacillussubtilis and Escherichiacoli in liquid and solid medium. Copyright © 2011 Elsevier Ltd. All rights reserved.

  14. Reducing Strength Prevailing at Root Surface of Plants Promotes Reduction of Ag+ and Generation of Ag0/Ag2O Nanoparticles Exogenously in Aqueous Phase

    PubMed Central

    Pardha-Saradhi, Peddisetty; Yamal, Gupta; Peddisetty, Tanuj; Sharmila, Peddisetty; Nagar, Shilpi; Singh, Jyoti; Nagarajan, Rajamani; Rao, Kottapalli S.

    2014-01-01

    Potential of root system of plants from wide range of families to effectively reduce membrane impermeable ferricyanide to ferrocyanide and blue coloured 2,6-dichlorophenol indophenol (DCPIP) to colourless DCPIPH2 both under non-sterile and sterile conditions, revealed prevalence of immense reducing strength at root surface. As generation of silver nanoparticles (NPs) from Ag+ involves reduction, present investigations were carried to evaluate if reducing strength prevailing at surface of root system can be exploited for reduction of Ag+ and exogenous generation of silver-NPs. Root system of intact plants of 16 species from 11 diverse families of angiosperms turned clear colorless AgNO3 solutions, turbid brown. Absorption spectra of these turbid brown solutions showed silver-NPs specific surface plasmon resonance peak. Transmission electron microscope coupled with energy dispersive X-ray confirmed the presence of distinct NPs in the range of 5–50 nm containing Ag. Selected area electron diffraction and powder X-ray diffraction patterns of the silver NPs showed Bragg reflections, characteristic of crystalline face-centered cubic structure of Ag0 and cubic structure of Ag2O. Root system of intact plants raised under sterile conditions also generated Ag0/Ag2O-NPs under strict sterile conditions in a manner similar to that recorded under non-sterile conditions. This revealed the inbuilt potential of root system to generate Ag0/Ag2O-NPs independent of any microorganism. Roots of intact plants reduced triphenyltetrazolium to triphenylformazon and impermeable ferricyanide to ferrocyanide, suggesting involvement of plasma membrane bound dehydrogenases in reduction of Ag+ and formation of Ag0/Ag2O-NPs. Root enzyme extract reduced triphenyltetrazolium to triphenylformazon and Ag+ to Ag0 in presence of NADH, clearly establishing potential of dehydrogenases to reduce Ag+ to Ag0, which generate Ag0/Ag2O-NPs. Findings presented in this manuscript put forth a novel, simple

  15. Ag/AgO Nanoparticles Grown via Time Dependent Double Mechanism in a 2D Layered Ni-PCP and Their Antibacterial Efficacy

    NASA Astrophysics Data System (ADS)

    Agarwal, Rashmi A.; Gupta, Neeraj K.; Singh, Rajan; Nigam, Shivansh; Ateeq, Bushra

    2017-03-01

    A simple synthesis route for growth of Ag/AgO nanoparticles (NPs) in large quantitative yields with narrow size distribution from a functional, non-activated, Ni (II) based highly flexible porous coordination polymer (PCP) as a template has been demonstrated. This template is a stable storage media for the NPs larger than the pore diameters of the PCP. From EPR study it was concluded that NPs were synthesized via two mechanisms i.e. acid formation and the redox activity of the framework. Size range of Ag/AgO NPs is sensitive to choice of solvent and reaction time. Direct use of Ag/AgO@Ni-PCP shows influential growth inhibition towards Escherichia coli and the pathogen Salmonella typhimurium at extremely low concentrations. The pristine template shows no cytotoxic activity, even though it contains Ni nodes in the framework.

  16. Comparative Cytotoxicity Study of Silver Nanoparticles (AgNPs) in a Variety of Rainbow Trout Cell Lines (RTL-W1, RTH-149, RTG-2) and Primary Hepatocytes

    PubMed Central

    Connolly, Mona; Fernandez-Cruz, Maria-Luisa; Quesada-Garcia, Alba; Alte, Luis; Segner, Helmut; Navas, Jose M.

    2015-01-01

    Among all classes of nanomaterials, silver nanoparticles (AgNPs) have potentially an important ecotoxicological impact, especially in freshwater environments. Fish are particularly susceptible to the toxic effects of silver ions and, with knowledge gaps regarding the contribution of dissolution and unique particle effects to AgNP toxicity, they represent a group of vulnerable organisms. Using cell lines (RTL-W1, RTH-149, RTG-2) and primary hepatocytes of rainbow trout (Oncorhynchus mykiss) as in vitro test systems, we assessed the cytotoxicity of the representative AgNP, NM-300K, and AgNO3 as an Ag+ ion source. Lack of AgNP interference with the cytotoxicity assays (AlamarBlue, CFDA-AM, NRU assay) and their simultaneous application point to the compatibility and usefulness of such a battery of assays. The RTH-149 and RTL-W1 liver cell lines exhibited similar sensitivity as primary hepatocytes towards AgNP toxicity. Leibovitz’s L-15 culture medium composition (high amino acid content) had an important influence on the behaviour and toxicity of AgNPs towards the RTL-W1 cell line. The obtained results demonstrate that, with careful consideration, such an in vitro approach can provide valuable toxicological data to be used in an integrated testing strategy for NM-300K risk assessment. PMID:26006119

  17. Electrical response from nanocomposite PDMS-Ag NPs generated by in situ laser ablation in solution

    NASA Astrophysics Data System (ADS)

    Kalyva, Maria; Kumar, Susmit; Brescia, Rosaria; Petroni, Simona; La Tegola, Carola; Bertoni, Giovanni; De Vittorio, Massimo; Cingolani, Roberto; Athanassiou, Athanassia

    2013-01-01

    Laser ablation technique is employed in order to generate polydimethylsiloxane (PDMS)/Ag NPs in situ, starting from a silver target in a solution of PDMS prepolymer and toluene. The produced surfactant-free nanoparticles are characterized by high resolution transmission electron microscopy (HRTEM) and scanning TEM-high angle annular dark field (STEM-HAADF) imaging modes, showing the majority of them to be of the order of 4 nm in diameter with a small percentage of larger Ag-AgCl multidomain NPs, embedded into a PDMS matrix. Low concentrations of carbon onion-like nanoparticles or larger fibers are also formed in the toluene-PDMS prepolymer solution. In accordance with this, UV-vis spectra shows no peak from silver NPs; their small size and their coverage by the PDMS matrix suppresses the signal of surface plasmon absorption. Inductively coupled plasma measurements reveal that the concentration of silver in the polymer is characteristically low, ˜0.001% by weight. The electrical properties of the PDMS nanocomposite films are modified, with current versus voltage (I-V) measurements showing a low current of up to a few tenths of a pA at 5 V. The surface resistivity of the films is found to be up to ˜1010 Ω/sq. Under pressure (e.g. stress) applied by a dynamic mechanical analyzer (DMA), the I-V measurements demonstrate the current decreasing during the elastic deformation, and increasing during the plastic deformation.

  18. The role of exopolymeric substances in the bioaccumulation and toxicity of Ag nanoparticles to algae

    NASA Astrophysics Data System (ADS)

    Zhou, Kaijun; Hu, Yi; Zhang, Luqing; Yang, Kun; Lin, Daohui

    2016-09-01

    Exopolymeric substances (EPS) have an important role in bioaccumulation and toxicity of nanoparticles (NPs) to algae, which warrants specific studies. The interaction of EPS with citrate and polyvinyl pyrrolidone (PVP) coated AgNPs (C-AgNPs and P-AgNPs, respectively) and its roles in bioaccumulation and toxicity of the AgNPs to Chlorella pyrenoidosa were investigated. The amino and aromatic carboxylic groups in the EPS were involved in the EPS-AgNP interactions. Compared with Ag+, C-AgNPs had comparable total bioaccumulation but greater absorption by intact algae with EPS; P-AgNPs had the smallest total bioaccumulation and were mainly adsorbed on algal surfaces. With EPS removed, the total bioaccumulations and surface adsorptions for the three Ag species decreased but the cell internalizations increased; the 96 h half growth inhibition concentrations decreased, indicating EPS alleviated the algal toxicity of Ag. The cell-internalized but not the adsorbed AgNPs could contribute to the nanotoxicity. The EPS could bind both AgNPs and Ag+, and thus inhibited the cell internalization and the nanotoxicity. However, the EPS-bound Ag on the cell surfaces would migrate along with the algae and be biologically amplified in the aquatic food chains, presenting ecological risks. These results are helpful for understanding the fate and ecological effects of NPs.

  19. A novel strategy for water disinfection with a AgNPs/gelatin sponge filter.

    PubMed

    Wei, Feng; Zhao, Xiaole; Li, Chao; Han, Xiaojun

    2018-05-05

    Disinfection of bacteria in water with sustainable and energy-efficient methods is still a great challenge. Herein, a novel gelatin sponge with embedded AgNPs is fabricated via freeze-drying using gelatin as the reducing agent to synthesize AgNPs in situ. UV-vis spectroscopy, HRTEM, XRD, and XPS characterization prove the formation of AgNPs with an average size of 8.55 ± 0.35 nm. TEM and SEM images confirm the even distribution of AgNPs throughout the AgNPs/gelatin sponges. The composite sponge has a low bulk density of 20 ± 3.5 mg/cm 3 and a pore size of 6.2 ± 1.5 μm. The AgNPs/gelatin sponges exhibit excellent antibacterial performance to E. coli in water, probably by destroying their cell membranes. The porous AgNPs/gelatin composite sponges are promising filter materials for water disinfection. The removal rate of AgNPs/gelatin composite sponges on E. coli reached almost 100%. Graphical abstract ᅟ.

  20. Antibacterial Activity Of ternary semiconductor compounds AgInSe2 Nanoparticles Synthesized by Simple Chemical Method

    NASA Astrophysics Data System (ADS)

    Shehab, A. A.; Fadaam, S. A.; Abd, A. N.; Mustafa, M. H.

    2018-05-01

    In this objective AgInSe2Nanoparticles (AgInSe2 NPs) were prepared by a simple chemical method (SCM). The optica structural l and morphological properties of the synthesized AgInSe2 NPs swere investigated by using UVVI absorption atomic force microscopy AFMmf, Fourier Transform Infrared Spectroscopy and x-ray diffraction. The resistance of bacteria represents a trouble and the outlook for the use of antibiotics in the future until now uncertain. Measures must be taken to decrease this problem. Antibacterial activity of the AgInSe2 nanoparticles were exposed against several pathogenic bacteriaa including Klebsiella pneumonia KPa, Staphylococcus aureus, Bacillus subtili, Enterobacter Cloacae and Esherichia Coliby. Using a good spread method the results showed that AgInSe2 NPs had inhibitory effect versus some pathogenic bacteria with suppression area 18, 14 and 17 mm for SAgInSe2 NPs had an inhibitory effect against S Bacillus Subtilis 11 mm K EnterobactercCloacae 12 mm.

  1. Speciation and Lability of Ag-, AgCl- and Ag2S-Nanoparticles in Soil Determined by X-ray Absorption Spectroscopy and Diffusive Gradients in Thin Films

    EPA Science Inventory

    Long-term speciation and lability of silver (Ag-), silver chloride (AgCl-) and silver sulfide nanoparticles (Ag2S-NPs) in soil were studied by X-ray absorption spectroscopy (XAS), and newly developed "nano" Diffusive Gradients in Thin Films (DGT) devices. These nano-D...

  2. Formation of Ag nanoparticles and enhancement of Tb3+ luminescence in Tb and Ag co-doped lithium-lanthanum-aluminosilicate glass

    NASA Astrophysics Data System (ADS)

    Piasecki, Patryk; Piasecki, Ashley; Pan, Zhengda; Mu, Richard; Morgan, Steven H.

    2010-12-01

    Tb3+ and Ag co-doped glass nano-composites were synthesized in a glass matrix Li2O-LaF3-Al2O3-SiO2 (LLAS) by a melt-quench technique. The growth of Ag nanoparticles (NPs) was controlled by a thermal annealing process. A broad absorption band peaking at about 420 nm was observed due to surface plasmon resonance (SPR) of Ag NPs. The intensity of this band grows with increasing annealing time. The transmission electron microscopic image (TEM) reveals the formation of Ag NPs in glass matrix. Photoluminescence (PL) emission and excitation spectra were measured for glass samples with different Ag concentrations and different annealing times. Plasmon enhanced Tb3+ luminescence was observed at certain excitation wavelength regions. Luminescence quenching was also observed for samples with high Ag concentration and longer annealing time. Our luminescence results suggest that there are two competitive effects, enhancement and quenching, acting on Tb3+ luminescence in the presence of Ag NPs. The enhancement of Tb3+ luminescence is mainly attributed to local field effects due to SPR. The quenching of luminescence suggests an energy transfer from Tb3+ ions to Ag NPs.

  3. Enhancing the photoelectrochemical response of TiO2 nanotubes through their nanodecoration by pulsed-laser-deposited Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Trabelsi, K.; Hajjaji, A.; Gaidi, M.; Bessais, B.; El Khakani, M. A.

    2017-08-01

    We report on the pulsed laser deposition (PLD) based nanodecoration of titanium dioxide (TiO2) nanotube arrays (NTAs) by Ag nanoparticles (NPs). We focus here on the investigation of the effect of the number of laser ablation pulses (NLP) of the silver target on both the average size of the Ag-NPs and the photoelectrochemical conversion efficiency of the Ag-NP decorated TiO2-NT based photoanodes. By varying the NLP, we were able to not only control the size of the PLD-deposited Ag nanoparticles from 20 to ˜50 nm, but also to increase concomitantly the surface coverage of the TiO2 NTAs by Ag-NPs. The red-shifting of the surface plasmon resonance peak of the PLD-deposited Ag-NPs deposited onto quartz substrates confirmed the increase of their size as the NLP is increased from 500 to 10 000. By investigating the photo-electrochemical properties of Ag-NP decorated TiO2-NTAs, by means of linear sweep cyclic voltammetry under UV-Vis illumination, we found that the generated photocurrent is sensitive to the size of the Ag-NPs and reaches a maximum value at NLP =500 (i.e.,; Ag-NP size of ˜20 nm). For NLP = 500, the photoconversion efficiency of the Ag-NP decorated TiO2-NTAs is shown to reach a maximum of 4.5% (at 0.5 V vs Ag/AgCl). The photocurrent enhancement of Ag-NP decorated TiO2-NTAs is believed to result from the additional light harvesting enabled by the ability of Ag-NPs to absorb visible irradiation caused by various localized surface plasmon resonances, which in turn depend on the size and interdistance of the Ag nanoparticles.

  4. Comparison of antibacterial activities of Ag@TiO2 and Ag@SiO2 core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Dhanalekshmi, K. I.; Meena, K. S.

    2014-07-01

    Core-shell type Ag@TiO2 nanoparticles were prepared by one pot simultaneous reduction of AgNO3 and hydrolysis of Ti (IV) isopropoxide and Ag@SiO2 core-shell nanoparticles were prepared by Stober's method. They were characterized by absorption, XRD, and HR-TEM techniques. XRD patterns show the presence of anatase form of TiO2 and amorphous form of SiO2 and the noble metal (Ag). High resolution transmission electron microscopy measurements revealed that their size is below 50 nm. The antibacterial properties of Ag@TiO2 and Ag@SiO2 core-shell nanoparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were examined by the agar diffusion method. As a result E. coli and S. aureus were shown to be substantially inhibited by Ag@TiO2 and Ag@SiO2 core-shell nanoparticles. These results demonstrated that TiO2 and SiO2 supported on the surface of Ag NPs without aggregation was proved to have enhanced antibacterial activity.

  5. Comparison of antibacterial activities of Ag@TiO2 and Ag@SiO2 core-shell nanoparticles.

    PubMed

    Dhanalekshmi, K I; Meena, K S

    2014-07-15

    Core-shell type Ag@TiO2 nanoparticles were prepared by one pot simultaneous reduction of AgNO3 and hydrolysis of Ti (IV) isopropoxide and Ag@SiO2 core-shell nanoparticles were prepared by Stober's method. They were characterized by absorption, XRD, and HR-TEM techniques. XRD patterns show the presence of anatase form of TiO2 and amorphous form of SiO2 and the noble metal (Ag). High resolution transmission electron microscopy measurements revealed that their size is below 50 nm. The antibacterial properties of Ag@TiO2 and Ag@SiO2 core-shell nanoparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were examined by the agar diffusion method. As a result E. coli and S. aureus were shown to be substantially inhibited by Ag@TiO2 and Ag@SiO2 core-shell nanoparticles. These results demonstrated that TiO2 and SiO2 supported on the surface of Ag NPs without aggregation was proved to have enhanced antibacterial activity. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Kinetic trapping through coalescence and the formation of patterned Ag-Cu nanoparticles

    NASA Astrophysics Data System (ADS)

    Grammatikopoulos, Panagiotis; Kioseoglou, Joseph; Galea, Antony; Vernieres, Jerome; Benelmekki, Maria; Diaz, Rosa E.; Sowwan, Mukhles

    2016-05-01

    In recent years, due to its inherent flexibility, magnetron-sputtering has been widely used to synthesise bi-metallic nanoparticles (NPs) via subsequent inert-gas cooling and gas-phase condensation of the sputtered atomic vapour. Utilising two separate sputter targets allows for good control over composition. Simultaneously, it involves fast kinetics and non-equilibrium processes, which can trap the nascent NPs into metastable configurations. In this study, we observed such configurations in immiscible, bi-metallic Ag-Cu NPs by scanning transmission electron microscopy (S/TEM) and electron energy-loss spectroscopy (EELS), and noticed a marked difference in the shape of NPs belonging to Ag- and Cu-rich samples. We explained the formation of Janus or Ag@Cu core/shell metastable structures on the grounds of in-flight mixed NP coalescence. We utilised molecular dynamics (MD) and Monte Carlo (MC) computer simulations to demonstrate that such configurations cannot occur as a result of nanoalloy segregation. Instead, sintering at relatively low temperatures can give rise to metastable structures, which eventually can be stabilised by subsequent quenching. Furthermore, we compared the heteroepitaxial diffusivities along various surfaces of both Ag and Cu NPs, and emphasised the differences between the sintering mechanisms of Ag- and Cu-rich NP compositions: small Cu NPs deform as coherent objects on large Ag NPs, whereas small Ag NPs dissolve into large Cu NPs, with their atoms diffusing along specific directions. Taking advantage of this observation, we propose controlled NP coalescence as a method to engineer mixed NPs of a unique, patterned core@partial-shell structure, which we refer to as a ``glass-float'' (ukidama) structure.In recent years, due to its inherent flexibility, magnetron-sputtering has been widely used to synthesise bi-metallic nanoparticles (NPs) via subsequent inert-gas cooling and gas-phase condensation of the sputtered atomic vapour. Utilising two

  7. A novel surface plasmon resonance biosensor based on the PDA-AgNPs-PDA-Au film sensing platform for horse IgG detection

    NASA Astrophysics Data System (ADS)

    Wang, Ning; Zhang, Di; Deng, Xinyu; Sun, Ying; Wang, Xinghua; Ma, Pinyi; Song, Daqian

    2018-02-01

    Herein we report a novel polydopamine-silver nanoparticle-polydopamine-gold (PDA-AgNPs-PDA-Au) film based surface plasmon resonance (SPR) biosensor for horse IgG detection. The PDA-AgNPs-PDA-Au film sensing platform was built on Au-film via layer-by-layer self-assembly. Ag ion was reduced in situ to AgNPs in presence of PDA. The top PDA layer can prevent AgNPs from being oxidized and connect with antibody via Schiff alkali reaction directly. The morphology and thickness of the modified gold film were characterized using scanning electron microscope and Talystep. Experimental results show that the PDA-AgNPs-PDA-Au film sensing platform is stable, regenerative and sensitive for horse IgG detection. The detection limit of horse IgG obtained with the present biosensor is 0.625 μg mL- 1, which is 2-fold and 4-fold lower than that obtained with biosensor based on PDA modified Au film and conventional biosensor based on MPA, respectively. Furthermore, when challenged to real serum samples, our sensor exhibited excellent specificity to horse IgG, suggesting its potential for industrial application.

  8. Fabrication of Ag nanoparticle catalyst supported on graphene for effective H2O2 nonenzymatic detection powered by chemical energy

    NASA Astrophysics Data System (ADS)

    Zhang, Hulin; Xie, Yuhang; Zhang, Shangjie; Wen, Yige; Chen, Changyong; Ye, Wenhao; Lin, Yuan

    2017-06-01

    Ag nanoparticles/graphene nanosheets (Ag NPs/GNs) have been fabricated using graphene nanosheets (GNs) as frames for the growth of Ag nanoparticles (Ag NPs). The graphene nanostructures adsorbed with a large number of Ag NPs and were synthesized via a facile redox reaction. The prepared nanocatalysts were characterized using x-ray diffraction, Raman spectroscopy, field electron scanning electron microscopy and transmission electron microscopy. The electrochemical activity of the Ag NPs/GNs for the detection of H2O2 was explored using cyclic voltammetry and chronoamperometry, indicating that the Ag NPs/GNs can remarkably facilitate H2O2 redox in phosphate buffer solution. Further comparative investigations show that the as-prepared Ag nanocatalysts exhibit a wide linear range, a high response, and a short response time for H2O2 detection. To further exploit the practical applications in H2O2 detection, the homemade electrochemical cells were employed to power the Ag NPs/GNs electrode sensor by chemical energy without external power sources. The results expand the applications of the graphene-based sensors and propose a feasible self-powered biochemical sensing approach independent of conventional power sources.

  9. Effects of Ag Nanoparticles on Growth and Fat Body Proteins in Silkworms (Bombyx mori).

    PubMed

    Meng, Xu; Abdlli, Nouara; Wang, Niannian; Lü, Peng; Nie, Zhichao; Dong, Xin; Lu, Shuang; Chen, Keping

    2017-12-01

    Ag nanoparticles (AgNPs), a widely used non-antibiotic, antibacterial material, have shown toxic and other potentially harmful effects in mammals. However, the deleterious effects of AgNPs on insects are still unknown. Here, we studied the effects of AgNPs on the model invertebrate organism Bombyx mori. After feeding silkworm larvae different concentrations of AgNPs, we evaluated the changes of B. mori body weights, survival rates, and proteomic differences. The results showed that low concentrations (<400 mg/L) of AgNPs promoted the growth and cocoon weights of B. mori. Although high concentrations (≥800 mg/L) of AgNPs also improved B. mori growth, they resulted in silkworm death. An analysis of fat body proteomic differences revealed 13 significant differences in fat body protein spots, nine of which exhibited significantly downregulated expression, while four showed significantly upregulated expression. Reverse transcription-polymerase chain reaction results showed that at an AgNP concentration of 1600 mg/L, the expression levels of seven proteins were similar to the transcription levels of their corresponding genes. Our results suggest that AgNPs lowered the resistance to oxidative stress, affected cell apoptosis, and induced cell necrosis by regulating related protein metabolism and metabolic pathways in B. mori.

  10. Simple and Sensitive Colorimetric Assay for Pb2+ Based on Glutathione Protected Ag Nanoparticles by Salt Amplification.

    PubMed

    Chen, Zhang; Li, Huidong; Chu, Lin; Liu, Chenbin; Luo, Shenglian

    2015-02-01

    A simple and sensitive colorimetric assay for Pb2+ detection has been reported using glutathione protected silver nanoparticles (AgNPs) by salt amplification. The naked AgNPs aggregate under the influence of salt. Glutathione (GSH) can bind to AgNPs via Ag-S bond, helping AgNPs to against salt-induced aggregation. However, GSH binding to AgNPs can be compromised by the interaction between Pb2+ and GSH. As a result, Pb2+-mediated aggregation of AgNPs under the influence of salt is reflected by the UV-Visible spectrum, and the qualitative and quantitative detection for Pb2+ is accomplished, with the detection range 0.5-4 µM and a detection limit of 0.5 µM. At the same time, Pb2+ in real water sample is detected. Furthermore, the high selectivity and low cost of the assay means it is promising for enviromental applications.

  11. E-beam deposited Ag-nanoparticles plasmonic organic solar cell and its absorption enhancement analysis using FDTD-based cylindrical nano-particle optical model.

    PubMed

    Kim, Richard S; Zhu, Jinfeng; Park, Jeung Hun; Li, Lu; Yu, Zhibin; Shen, Huajun; Xue, Mei; Wang, Kang L; Park, Gyechoon; Anderson, Timothy J; Pei, Qibing

    2012-06-04

    We report the plasmon-assisted photocurrent enhancement in Ag-nanoparticles (Ag-NPs) embedded PEDOT:PSS/P3HT:PCBM organic solar cells, and systematically investigate the causes of the improved optical absorption based on a cylindrical Ag-NPs optical model which is simulated with a 3-Dimensional finite difference time domain (FDTD) method. The proposed cylindrical Ag-NPs optical model is able to explain the optical absorption enhancement by the localized surface plasmon resonance (LSPR) modes, and to provide a further understanding of Ag-NPs shape parameters which play an important role to determine the broadband absorption phenomena in plasmonic organic solar cells. A significant increase in the power conversion efficiency (PCE) of the plasmonic solar cell was experimentally observed and compared with that of the solar cells without Ag-NPs. Finally, our conclusion was made after briefly discussing the electrical effects of the fabricated plasmonic organic solar cells.

  12. Biological studies and electrical conductivity of paper sheet based on PANI/PS/Ag-NPs nanocomposite.

    PubMed

    Youssef, A M; Mohamed, S A; Abdel-Aziz, M S; Abdel-Aziz, M E; Turky, G; Kamel, S

    2016-08-20

    Polyaniline (PANI) with/without polystyrene (PS), was successfully manufactured in the occurrence of dispersed pulp fibers via the oxidative polymerization reaction of aniline monomer to produce conductive paper sheets containing PANI, PANI/PS composites. Additionally, sliver nitrate (Ag-NO3) was added by varied loadings to the oxidative polymerization of aniline monomer to provide sliver nanoparticles (Ag-NPs) emptied into the prepared paper sheets. The prepared paper sheets were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD) and infrared spectroscopy (IR), the mechanical properties of the prepared paper sheets were evaluated. Moreover, the electrical conductivity and biological studies such as cellulases assay, Microorganism & culture condition and detection of the released of Ag-NPs were evaluated. Furthermore, the prepared paper sheets were displayed good antibacterial properties contrary to gram positive and gram negative bacteria. Consequently, the prepared paper sheet may be used as novel materials for packaging applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Antifungal mechanisms of ZnO and Ag nanoparticles to Sclerotinia homoeocarpa

    NASA Astrophysics Data System (ADS)

    Li, Junli; Sang, Hyunkyu; Guo, Huiyuan; Popko, James T.; He, Lili; White, Jason C.; Parkash Dhankher, Om; Jung, Geunhwa; Xing, Baoshan

    2017-04-01

    Fungicides have extensively been used to effectively combat fungal diseases on a range of plant species, but resistance to multiple active ingredients has developed in pathogens such as Sclerotinia homoeocarpa, the causal agent of dollar spot on cool-season turfgrasses. Recently, ZnO and Ag nanoparticles (NPs) have received increased attention due to their antimicrobial activities. In this study, the NPs’ toxicity and mechanisms of action were investigated as alternative antifungal agents against S. homoeocarpa isolates that varied in their resistance to demethylation inhibitor (DMI) fungicides. S. homoeocarpa isolates were treated with ZnO NPs and ZnCl2 (25-400 μg ml-1) and Ag NPs and AgNO3 (5-100 μg ml-1) to test antifungal activity of the NPs and ions. The mycelial growth of S. homoeocarpa isolates regardless of their DMI sensitivity was significantly inhibited on ZnO NPs (≥200 μg ml-1), Ag NPs (≥25 μg ml-1), Zn2+ ions (≥200 μg ml-1), and Ag+ ions (≥10 μg ml-1) amended media. Expression of stress response genes, glutathione S-transferase (Shgst1) and superoxide dismutase 2 (ShSOD2), was significantly induced in the isolates by exposure to the NPs and ions. In addition, a significant increase in the nucleic acid contents of fungal hyphae, which may be due to stress response, was observed upon treatment with Ag NPs using Raman spectroscopy. We further observed that a zinc transporter (Shzrt1) might play an important role in accumulating ZnO and Ag NPs into the cells of S. homoeocarpa due to overexpression of Shzrt1 significantly induced by ZnO or Ag NPs within 3 h of exposure. Yeast mutants complemented with Shzrt1 became more sensitive to ZnO and Ag NPs as well as Zn2+ and Ag+ ions than the control strain and resulted in increased Zn or Ag content after exposure. This is the first report of involvement of the zinc transporter in the accumulation of Zn and Ag from NP exposure in filamentous plant pathogenic fungi. Understanding the molecular

  14. Photocatalytic activity of Ag/ZnO core-shell nanoparticles with shell thickness as controlling parameter under green environment

    NASA Astrophysics Data System (ADS)

    Rajbongshi, Himanshu; Bhattacharjee, Suparna; Datta, Pranayee

    2017-02-01

    Plasmonic Ag/ZnO core-shell nanoparticles have been synthesized via a simple two-step wet chemical method for application in Photocatalysis. The morphology, size, crystal structure, composition and optical properties of the nanoparticles are investigated by x-ray diffraction, transmission electron microscopy (TEM), FTIR spectroscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy and photoluminescence (PL) spectroscopy. The shell thicknesses are varied by varying the concentration of zinc nitrate hexa-hydrate and triethanolamine. The ZnO shell coating over Ag core enhances the charge separation, whereas the larger shell thickness and increased refractive index of surrounding medium cause red shifts of surface Plasmon resonance (SPR) peak of Ag core. The photoluminescence (PL) spectra of Ag/ZnO core-shell show that the larger shell thickness quenches the near band edge UV emission of ZnO. The electrochemical impedance spectra (EIS) i.e. Nyquist plots also confirm the higher charge transfer efficiency of the Ag/ZnO core-shell nanoparticles. The Photocatalytic activities of Ag/ZnO core-shell nanoparticles are investigated by the degradation of methylene blue (MB) dye under direct sunlight irradiation. Compared to pure ZnO nanoparticles (NPs), Ag/ZnO core-shell NPs display efficient sunlight plasmonic photocatalytic activity because of the influence of SPR of Ag core and the electron sink effect. The photocatalytic activity of Ag/ZnO core-shell NPs is found to be enhanced with increase in shell thickness.

  15. Pt@Ag and Pd@Ag core/shell nanoparticles for catalytic degradation of Congo red in aqueous solution

    NASA Astrophysics Data System (ADS)

    Salem, Mohamed A.; Bakr, Eman A.; El-Attar, Heba G.

    2018-01-01

    Platinum/silver (Pt@Ag) and palladium/silver (Pd@Ag) core/shell NPs have been synthesized in two steps reaction using the citrate method. The progress of nanoparticle formation was followed by the UV/Vis spectroscopy. Transmission electron microscopy revealed spherical shaped core/shell nanoparticles with average particle diameter 32.17 nm for Pt@Ag and 8.8 nm for Pd@Ag. The core/shell NPs were further characterized by FT-IR and XRD. Reductive degradation of the Congo red dye was chosen to demonstrate the excellent catalytic activity of these core/shell nanostructures. The nanocatalysts act as electron mediators for the transfer of electrons from the reducing agent (NaBH4) to the dye molecules. Effect of reaction parameters such as nanocatalyst dose, dye and NaBH4 concentrations on the dye degradation was investigated. A comparison between the catalytic activities of both nanocatalysts was made to realize which of them the best in catalytic performance. Pd@Ag was the higher in catalytic activity over Pt@Ag. Such greater activity is originated from the smaller particle size and larger surface area. Pd@Ag nanocatalyst was catalytically stable through four subsequent reaction runs under the utilized reaction conditions. These findings can thus be considered as possible economical alternative for environmental safety against water pollution by dyes.

  16. Antimicrobial and anticancer activity of AgNPs coated with Alphonsea sclerocarpa extract.

    PubMed

    Doddapaneni, Suman Joshi D S; Amgoth, Chander; Kalle, Arunasree M; Suryadevara, Surya Narayana; Alapati, Krishna Satya

    2018-03-01

    The synthesis and characterization of an aggregate of AgNPs coated with plant extract (PE) from Alphonsea sclerocarpa and its significant antimicrobial activity and inhibition on K562 (blood cancer) cells have been appended in the article. Synthesis of aggregate [(AgNPs)-(PE)] has been followed by a facile eco-friendly approach without using any harmful chemicals. The morphology of an aggregate [(AgNPs)-(PE)] was confirmed by TEM and SEM microscopic characterizations. Properties like solid state, the presence of functional groups, and elemental composition have been characterized through the XRD, FTIR, and EDAX. The biocompatibility of synthesized aggregate of [(AgNPs)-(PE)] was confirmed by the MTT assay. An in vitro cell (HEK293)-based studies were performed for the biocompatibility tests and it is found that the aggregate [(AgNPs)-(PE)] is not harmful to normal/healthy cells. Even though A. sclerocarpa show the antimicrobial (antibacterial and antifungal) activity, it has been further enhanced with the developed aggregate of [(AgNPs)-(PE)]. Furthermore, it has been extended to examine the cellular inhibition on K562 cells and obtained > 75% cell inhibition for 24 h treated cells.

  17. Simplifying the growth of hybrid single-crystals by using nanoparticle precursors: the case of AgI

    NASA Astrophysics Data System (ADS)

    Xu, Biao; Wang, Ruji; Wang, Xun

    2012-03-01

    We report the synthesis of a series of AAgmIn single-crystals within 24 h, at room temperature, utilizing AgI nanoparticles (NPs) as the precursor. The AgI NPs impart high reactivity under mild conditions and favor the growth kinetics. 0D, 1D and 2D iodoargentate crystals can be obtained. This work represents the first application of NPs in the field of organo-metal-halide crystals and will inspire the design of other AMmXn crystals.We report the synthesis of a series of AAgmIn single-crystals within 24 h, at room temperature, utilizing AgI nanoparticles (NPs) as the precursor. The AgI NPs impart high reactivity under mild conditions and favor the growth kinetics. 0D, 1D and 2D iodoargentate crystals can be obtained. This work represents the first application of NPs in the field of organo-metal-halide crystals and will inspire the design of other AMmXn crystals. Electronic supplementary information (ESI) available: XPS spectra of AgI NPs, schematic representation of the formation process of [Ag4I8]4- in 2, UV-Vis spectra of the DTMA-Ag-I clusters, analysis of force balance of a crystal at the interface between H2O and CH2Cl2 and crystal structure depiction of 1-4. CIF files of 1-4 are also provided. CCDC reference numbers 863848, 863849, 863850 and 863851. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2nr30139c

  18. Fabrication of Ag-Au bimetallic nanoparticles by laser-induced dewetting of bilayer films

    NASA Astrophysics Data System (ADS)

    Oh, Yoonseok; Lee, Jeeyoung; Lee, Myeongkyu

    2018-03-01

    We here show that Ag-Au bimetallic nanoparticles (NPs) can be produced by dewetting an Ag/Au bilayer film coated on glass using a nanosecond-pulsed laser beam. Elemental analysis revealed that the obtained bimetallic NPs are Ag-Au alloys, with two elements well mixed over the whole volume of the particle. The composition of the produced particles was controllable by changing the relative thickness of each layer. The localized surface plasmon resonance (LSPR) peak was red-shifted with an increasing Au content and the LSPR wavelength could be tuned from 415 to 525 nm by varying the alloy composition. A film area of several square centimeters could be transformed into Ag-Au NPs by a single laser pulse of 6 ns duration. This study provides a facile and scalable route to prepare bimetallic NPs for plasmonic and other applications.

  19. Structural mechanical and antibacterial properties of HPMC/SF-AgNPs nanocomposite films

    NASA Astrophysics Data System (ADS)

    Harish, K. V.; Rao, B. Lakshmeesha; Asha, S.; Vipin, C.; Sangappa, Y.

    2018-04-01

    In the present study, Hydroxypropyl Methylcellulose (HPMC) pure and HPMC/SF-AgNPs biopolymer nanocomposite films were prepared by simple solution casting method. The prepared nanocomposite films were characterized using UV-Visible spectroscopy(UV-Vis), X-ray diffraction (XRD) measurements. The mechanical properties of HPMC/SF-AgNPs nanocomposites were found to be decrease with increase in the AgNP's concentrations. The HPMC/SF-AgNPs nanocomposites showed very good antibacterial activity against human pathogens P. aeruginosa, E.coli, and S.aureus.

  20. Improved diode performance of Ag nanoparticle dispersed Er doped In2O3 film

    NASA Astrophysics Data System (ADS)

    Ghosh, Anupam; Dwivedi, Shyam Murli Manohar Dhar; Chakrabartty, Shubhro; Mondal, Aniruddha

    2018-04-01

    Ag nanoparticle(NP) dispersedEr doped In2O3 film was prepared by sol-gel method followed by thermal evaporation cum glancing angle deposition technique. The Schottky contact based devicecontaining Ag NPs shows ideality factor of ˜180 at 10 K and ˜5 at 300 K, which is lesser as compared to the device that does not contain Ag NPs. The lower ideality factor value all over the temperature range makes the diode more reliable.

  1. Internally dispersed synthesis of uniform silver nanoparticles via in situ reduction of [Ag(NH3)2]+ along natural microfibrillar substructures of cotton fiber

    USDA-ARS?s Scientific Manuscript database

    Silver nanoparticles (Ag NPs) are known to have efficient antimicrobial properties, but the direct application of Ag NPs onto the surface of textiles has shown to be ineffective and raise environmental concerns because Ag NPs leach out during washing. In this study, non-leaching and stable Agcotton ...

  2. Structural and biological evaluation of a multifunctional SWCNT-AgNPs-DNA/PVA bio-nanofilm.

    PubMed

    Subbiah, Ramesh P; Lee, Haisung; Veerapandian, Murugan; Sadhasivam, Sathya; Seo, Soo-Won; Yun, Kyusik

    2011-04-01

    A bio-nanofilm consisting of a tetrad nanomaterial (nanotubes, nanoparticles, DNA, polymer) was fabricated utilizing in situ reduction and noncovalent interactions and it displayed effective antibacterial activity and biocompatibility. This bio-nanofilm was composed of homogenous silver nanoparticles (AgNPs) coated on single-walled carbon nanotubes (SWCNTs), which were later hybridized with DNA and stabilized in poly(vinyl alcohol) (PVA) in the presence of a surfactant with the aid of ultrasonication. Electron microscopy and bio-AFM (atomic force microscopy) images were used to assess the morphology of the nanocomposite (NC) structure. Functionalization and fabrication were examined using FT-Raman spectroscopy by analyzing the functional changes in the bio-nanofilm before and after fabrication. UV-visible spectroscopy and X-ray powder diffraction (XRD) confirmed that AgNPs were present in the final NC on the basis of its surface plasmon resonance (370 nm) and crystal planes. Thermal gravimetric analysis was used to measure the percentage weight loss of SWCNT (17.5%) and final SWCNT-AgNPs-DNA/PVA (47.7%). The antimicrobial efficiency of the bio-nanofilm was evaluated against major pathogenic organisms. Bactericidal ratios, zone of inhibition, and minimum inhibitory concentration were examined against gram positive and gram negative bacteria. A preliminary cytotoxicity analysis was conducted using A549 lung cancer cells and IMR-90 fibroblast cells. Confocal laser microscopy, bio-AFM, and field emission scanning electron microscopy (FE-SEM) images demonstrated that the NCs were successfully taken up by the cells. These combined results indicate that this bio-nanofilm was biocompatible and displayed antimicrobial activity. Thus, this novel bio-nanofilm holds great promise for use as a multifunctional tool in burn therapy, tissue engineering, and other biomedical applications.

  3. Bioaccumulation of Zn and Ag Nanoparticles in the Earthworms (Eisenia fetida)

    NASA Astrophysics Data System (ADS)

    Ha, Lee Seung; Sung-Dae, Kim; Yi, Yang Song; Byeong-Gweon, Lee

    2014-05-01

    Many studies are carried out to evaluate environmental effects of engineered nanoparticles (ENPs). Most of the previous studies primarily focused on the effects of nanoparticles into the aquatic environment and human. Model studies predict that ENPs released into environment would transferred primarily to the soil of the terrestrial environment. Despite this prediction, biogeochemical behavior of ENPs in soil environment as well as bioavailability of ENPs to soil-dwelling organisms such as earthworm, springtail, isopod and nematodes are poorly understood. The main goal of this study was to compare the bioaccumulation factor (BAFs) and subcellular partitioning of nanoparticles in the soil-dwelling earthworm (Eisenia fetida) from ENP (ZnO and Ag nanoparticles) or ionic metal (Zn2+, Ag+) contaminated soil. And the sequential extraction was also used to determine the mobility of metals in soil which could be used as to predict bioavailability and compare that with bioaccumulation factor. The radiotracer method was employed to trace the transfer of ENPs and ionic metal among different environmental media and animals. Radiolabeled 65ZnO, 110mAgNPs coated with PVP or citrate were synthesized in the laboratory and their chemical and biological behavior was compared to ionic 65Zn and 110mAg. The BAFs of Zn and Ag in the earthworms were determined after animals exposed to the contaminated soils. After the 7 days of elimination phase, subcellular partitioning of metals were also obtained. BAF for ZnO(0.06) was 31 times lower than that for Zn ion (1.86), suggesting that ZnO was less bioavailable than its ionic form from contaminated soil. On the other hands, BAFs for AgNPs coated with PVP (0.12) or with citrate (0.11) were comparable to those for Ag ion (0.17), indicating that Ag from contaminated soil was bioavailable in a similar rate regardless of chemical forms. The subcellular partitioning results showed that bioaccumulated Zn from Zn ion and ZnO contaminated soil were

  4. Nanoscale coupling of photons to vibrational excitation of Ag nanoparticle 2D array studied by scanning tunneling microscope light emission spectroscopy.

    PubMed

    Katano, Satoshi; Toma, Koji; Toma, Mana; Tamada, Kaoru; Uehara, Yoichi

    2010-11-28

    Scanning tunneling microscope light emission (STM-LE) spectroscopy has been utilized to elucidate the luminescence phenomena of Ag nanoparticles capped with myristate (myristate-capped AgNP) and 2-methyl-1-propanethiolate (C(4)S-capped AgNP) on the dodecanethiol-precovered Au substrate. The STM imaging revealed that myristate-capped AgNPs form an ordered hexagonal array whereas C(4)S-capped AgNPs show imperfect ordering, indicating that a shorter alkyl chain of C(4)S-capped AgNP is not sufficient to form rigid interdigitation. It should be noted that such a nanoparticle ordering affects the luminescence properties of the Ag nanoparticle. We found that the STM-LE is only detected from the Ag nanoparticles forming the two-dimensional superlattice. This indicates that the STM-LE of the Ag nanoparticle is radiated via the collective excitation of the local surface plasmon resonance (LSPR) spread over the Ag nanoparticles. Note that the STM-LE spectra of the Ag nanoparticles exhibit spike-like peaks superimposed on the broad light emission peak. Using Raman spectroscopy, we concluded that the spike-like structure appearing in the STM-LE spectra is associated with the vibrational excitation of the molecule embedded between Ag nanoparticles.

  5. Insights into the proteomic response of soybean towards Al₂O₃, ZnO, and Ag nanoparticles stress.

    PubMed

    Hossain, Zahed; Mustafa, Ghazala; Sakata, Katsumi; Komatsu, Setsuko

    2016-03-05

    Understanding the complex mechanisms involved in plant response to nanoparticles is indispensable in assessing the impact of nano-pollutants on environment. The present study compares the phytotoxicity of three different metal-based nanoparticles (Al2O3, ZnO, and Ag) in soybean seedling at proteome level. Plant growth, rigidity of roots, and root cell viability were markedly affected by ZnO- and Ag-NPs stress; while, Al2O3-NPs challenged soybean maintained normal seedling growth like control. Moreover, severe oxidative burst was evident in ZnO-NPs and Ag-NPs treatments. Gel-free proteomic analysis of NPs stressed soybean roots revealed 104 commonly changed proteins primarily associated with secondary metabolism, cell organization, and hormone metabolism. Oxidation-reduction cascade related genes, such as GDSL motif lipase 5, SKU5 similar 4, galactose oxidase, and quinone reductase were up-regulated in Al2O3-NPs challenged roots and down-regulated in ZnO- and Ag-NPs treatments. In comparison to root, 16 common proteins were found to be significantly changed in leaves of NPs exposed soybean that were predominantly associated to photosystem and protein degradation. The proteomic findings suggest that high abundance of proteins involved in oxidation-reduction, stress signaling, hormonal pathways related to growth and development might be the principal key for optimum growth of soybean under Al2O3-NPs stress. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Guazuma ulmifolia bark-synthesized Ag, Au and Ag/Au alloy nanoparticles: Photocatalytic potential, DNA/protein interactions, anticancer activity and toxicity against 14 species of microbial pathogens.

    PubMed

    Karthika, Viswanathan; Arumugam, Ayyakannu; Gopinath, Kasi; Kaleeswarran, Periyannan; Govindarajan, Marimuthu; Alharbi, Naiyf S; Kadaikunnan, Shine; Khaled, Jamal M; Benelli, Giovanni

    2017-02-01

    In the present study, we focused on a quick and green method to fabricate Ag, Au and Ag/Au alloy nanoparticles (NPs) using the bark extract of Guazuma ulmifolia L. Green synthesized metal NPs were characterized using different techniques, including UV-Vis spectroscopy, FT-IR, XRD, AFM and HR-TEM analyses. The production of Ag, Au and Ag/Au alloy NPs was observed monitoring color change from colorless to brown, followed by pink and dark brown, as confirmed by UV-Vis spectroscopy characteristic peaks at 436, 522 and 510nm, respectively. TEM shed light on the spherical shapes of NPs with size ranges of 10-15, 20-25 and 10-20nm. Biosynthesized NPs showed good catalytic activity reducing two organic dyes, 4-nitrophenol (4-NP) and Congo red (CR). UV-vis spectroscopy, fluorescence, circular dichroism spectroscopy and viscosity analyses were used to investigate the NP binding with calf thymus DNA. The binding constant of NPs with DNA calculated in UV-Vis absorption studies were 1.18×10 4 , 1.83×10 4 and 2.91×10 4 M -1 , respectively, indicating that NPs were able to bind DNA with variable binding affinity: Ag/Au alloy NPs>Ag NPs>Au NPs. Ag/Au alloy NPs also showed binding activity to bovine serum albumin (BSA) over the other NPs. Ag and Ag/Au alloy NPs exhibited good antimicrobial activity on 14 species of microbial pathogens. In addition, the cytotoxic effects of Ag/Au alloy NPs were studied on human cervical cancer cells (HeLa) using MTT assay. Overall, our work showed the promising potential of bark-synthesized Ag and Ag/Au alloy NPs as cheap sources to develop novel and safer photocatalytic, antimicrobial and anticancer agents. Copyright © 2017. Published by Elsevier B.V.

  7. Continuous-flow biosynthesis of Au-Ag bimetallic nanoparticles in a microreactor

    NASA Astrophysics Data System (ADS)

    Liu, Hongyu; Huang, Jiale; Sun, Daohua; Odoom-Wubah, Tareque; Li, Jun; Li, Qingbiao

    2014-11-01

    Herein, a microfluidic biosynthesis of Au-Ag bimetallic nanoparticle (NP) in a tubular microreactor, based on simultaneous reduction of HAuCl4 and AgNO3 precursors in the presence of Cacumen Platycladi ( C. Platycladi) extract was studied. The flow velocity profile was numerically analyzed with computational fluid dynamics. Au-Ag bimetallic NPs with Ag/Au molar ratios of 1:1 and 2:1 were synthesized, respectively. The alloy formation, morphology, structure, and size were investigated by UV-Vis spectra analysis, transmission electron microscopy (TEM), high resolution TEM, scanning TEM, and energy-dispersive X-ray analysis. In addition, the effects of volumetric flow rate, reaction temperature, and concentration of C. Platycladi extract and NaOH on the properties of the as-synthesized Au-Ag bimetallic NPs were investigated. The results indicated that these factors could not only affect the molar ratios of the two elements in the Au-Ag bimetallic NPs, but also affect particle size which can be adjusted from 3.3 to 5.6 nm. The process was very rapid and green, since a microreactor was employed with no additional synthetic reagents used. This work is anticipated to provide useful parameters for continuous-flow biosynthesis of bimetallic NPs in microreactors.

  8. Pt@Ag and Pd@Ag core/shell nanoparticles for catalytic degradation of Congo red in aqueous solution.

    PubMed

    Salem, Mohamed A; Bakr, Eman A; El-Attar, Heba G

    2018-01-05

    Platinum/silver (Pt@Ag) and palladium/silver (Pd@Ag) core/shell NPs have been synthesized in two steps reaction using the citrate method. The progress of nanoparticle formation was followed by the UV/Vis spectroscopy. Transmission electron microscopy revealed spherical shaped core/shell nanoparticles with average particle diameter 32.17nm for Pt@Ag and 8.8nm for Pd@Ag. The core/shell NPs were further characterized by FT-IR and XRD. Reductive degradation of the Congo red dye was chosen to demonstrate the excellent catalytic activity of these core/shell nanostructures. The nanocatalysts act as electron mediators for the transfer of electrons from the reducing agent (NaBH 4 ) to the dye molecules. Effect of reaction parameters such as nanocatalyst dose, dye and NaBH 4 concentrations on the dye degradation was investigated. A comparison between the catalytic activities of both nanocatalysts was made to realize which of them the best in catalytic performance. Pd@Ag was the higher in catalytic activity over Pt@Ag. Such greater activity is originated from the smaller particle size and larger surface area. Pd@Ag nanocatalyst was catalytically stable through four subsequent reaction runs under the utilized reaction conditions. These findings can thus be considered as possible economical alternative for environmental safety against water pollution by dyes. Copyright © 2017. Published by Elsevier B.V.

  9. Ag Nanoparticles-enhanced Fluorescence of Terbium-Deferasirox Complexes for the Highly Sensitive Determination of Deferasirox.

    PubMed

    Abolhasani, Jafar; Naderali, Roza; Hassanzadeh, Javad

    2016-01-01

    We describe the effect of different sized gold and silver nanoparticles on the terbium sensitized fluorescence of deferasirox. It is indicated that silver nanostructures, especially 18 nm Ag nanoparticles (AgNPs), have a remarkable amplifying effect compared to Au nanoparticles. Based on this observation, a highly sensitive and selective method was developed for the determination of deferasirox. Effects of various parameters like AgNPs and Tb(3+) concentration and pH of media were investigated. Under the optimal conditions, a calibration curve was plotted as the fluorescence intensities versus the concentration of deferasirox in the range of 0.1 to 200 nmol L(-1), and detection limit of 0.03 nmol L(-1) was obtained. The method has good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of deferasirox in urine and pharmaceutical samples.

  10. Interactions of aqueous Ag+ with fulvic acids: mechanisms of silver nanoparticle formation and investigation of stability.

    PubMed

    Adegboyega, Nathaniel F; Sharma, Virender K; Siskova, Karolina; Zbořil, Radek; Sohn, Mary; Schultz, Brian J; Banerjee, Sarbajit

    2013-01-15

    This study investigated the possible natural formation of silver nanoparticles (AgNPs) in Ag(+)-fulvic acid (FA) solutions under various environmentally relevant conditions (temperature, pH, and UV light). Increase in temperature (24-90 °C) and pH (6.1-9.0) of Ag(+)-Suwannee River fulvic acid (SRFA) solutions accelerated the appearance of the characteristic surface plasmon resonance (SPR) of AgNPs. The rate of AgNP formation via reduction of Ag(+) in the presence of different FAs (SRFA, Pahokee Peat fulvic acid, PPFA, Nordic lake fulvic acid, NLFA) and Suwannee River humic acid (SRHA) followed the order NLFA > SRHA > PPFA > SRFA. This order was found to be related to the free radical content of the acids, which was consistent with the proposed mechanism. The same order of AgNP growth was seen upon UV light illumination of Ag(+)-FA and Ag(+)-HA mixtures in moderately hard reconstituted water (MHRW). Stability studies of AgNPs, formed from the interactions of Ag(+)-SRFA, over a period of several months showed that these AgNPs were highly stable with SPR peak reductions of only ~15%. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements revealed bimodal particle size distributions of aged AgNPs. The stable AgNPs formed through the reduction of Ag(+) by fulvic and humic acid fractions of natural organic matter in the environment may be transported over significant distances and might also influence the overall bioavailability and ecotoxicity of AgNPs.

  11. High-efficient catalytic reduction of 4-nitrophenol based on reusable Ag nanoparticles/graphene-loading loofah sponge hybrid.

    PubMed

    Liu, Y Y; Zhao, Y H; Zhou, Y; Guo, X L; Chen, Z T; Zhang, W J; Zhang, Y; Chen, J; Wang, Z M; Sun, L T; Zhang, T

    2018-08-03

    Noble metal nanoparticles (NPs) such as Au and Ag have shown many applications in the field of catalysis, sensing etc. due to their excellent photoelectric properties. But agglomeration and a low recovery rate are big problems for their applications. In this research, a novel Ag NPs/graphene (reduced graphene oxide)-loading loofah sponge (Ag NPs/RGO-LS) was synthesized through a one-step reduction method. Where the RGO is used as a nano-support with the high specific surface area and the high conductivity to prevent the agglomeration of Ag NPs and provide a conductive layer. The natural, green, low-cost and high-yield LS is designed as a macro-support to reduce the loss of Ag NPs during recycling. The as-prepared Ag NPs/RGO-LS is stable, uniform, and exhibits high efficiency and reusability in the catalytic reduction of 4-nitrophenol (4-NP) with a high rate constant of 1.893 min -1 as well as an average conversion of 98% in 6 min during five cycles. The results have not only paved the way for the wide application of Ag NPs but also provide a new road for the application of other metal NPs.

  12. Antimicrobial and cell viability measurement of bovine serum albumin capped silver nanoparticles (Ag/BSA) loaded collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film.

    PubMed

    Bakare, Rotimi; Hawthrone, Samantha; Vails, Carmen; Gugssa, Ayele; Karim, Alamgir; Stubbs, John; Raghavan, Dharmaraj

    2016-03-01

    Bacterial infection of orthopedic devices has been a major concern in joint replacement procedures. Therefore, this study is aimed at formulating collagen immobilized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) film loaded with bovine serum albumin capped silver nanoparticles (Ag/BSA NPs) to inhibit bacterial growth while retaining/promoting osteoblast cells viability. The nanoparticles loaded collagen immobilized PHBV film was characterized for its composition by X-ray Photoelectron Spectroscopy and Anodic Stripping Voltammetry. The extent of loading of Ag/BSA NPs on collagen immobilized PHBV film was found to depend on the chemistry of the functionalized PHBV film and the concentration of Ag/BSA NPs solution used for loading nanoparticles. Our results showed that more Ag/BSA NPs were loaded on higher molecular weight collagen immobilized PHEMA-g-PHBV film. Maximum loading of Ag/BSA NPs on collagen immobilized PHBV film was observed when 16ppm solution was used for adsorption studies. Colony forming unit and optical density measurements showed broad antimicrobial activity towards Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa at significantly lower concentration i.e., 0.19 and 0.31μg/disc, compared to gentamicin and sulfamethoxazole trimethoprim while MTT assay showed that released nanoparticles from Ag/BSA NPs loaded collagen immobilized PHBV film has no impact on MCTC3-E1 cells viability. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Green Synthesis of AgNPs Stabilized with biowaste and their antimicrobial activities

    PubMed Central

    Jasuja, Nakuleshwar Dut; Gupta, Deepak Kumar; Reza, Mohtashim; Joshi, Suresh C.

    2014-01-01

    In the present study, rapid reduction and stabilization of Ag+ ions with different NaOH molar concentration (0.5 mM, 1.0 mM and 1.5 mM) has been carried out in the aqueous solution of silver nitrate by the bio waste peel extract of P.granatum. Generally, chemical methods used for the synthesis of AgNPs are quite toxic, flammable and have adverse effect in medical application but green synthesis is a better option due to eco-friendliness, non-toxicity and safe for human. Stable AgNPs were synthesized by treating 90 mL aqueous solution of 2 mM AgNO3 with the 5 mL plant peels extract (0.4% w/v) at different NaOH concentration (5 mL). The synthesized AgNPs were characterized by UV-Vis spectroscopy, TEM and SEM. Further, antimicrobial activities of AgNPs were performed on Gram positive i.e. Staphylococcus aureus, Bacillus subtilius and Gram negative i.e. E. coli, Pseudomonas aeruginosa bacteria. The AgNPs synthesized at 1.5 mM NaOH concentration had shown maximum zone of inhibition (ZOI) i.e. 49 ± 0.64 in E. coli, whereas Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilius had shown 40 ± 0.29 mm, 28 ± 0.13 and 42 ± 0.49 mm ZOI respectively. The MIC value of 30 μg/mL observed for E. coli Whereas, Staphylococcus aureus, Bacillus subtilius and Pseudomonas aeruginosa had shown 45 μg/mL, 38 μg/mL, 35 μg/mL respectively. The study revealed that AgNPs had shown significant antimicrobial activity as compared to Streptomycin. PMID:25763037

  14. Green Synthesis of AgNPs Stabilized with biowaste and their antimicrobial activities.

    PubMed

    Jasuja, Nakuleshwar Dut; Gupta, Deepak Kumar; Reza, Mohtashim; Joshi, Suresh C

    2014-01-01

    In the present study, rapid reduction and stabilization of Ag+ ions with different NaOH molar concentration (0.5 mM, 1.0 mM and 1.5 mM) has been carried out in the aqueous solution of silver nitrate by the bio waste peel extract of P.granatum. Generally, chemical methods used for the synthesis of AgNPs are quite toxic, flammable and have adverse effect in medical application but green synthesis is a better option due to eco-friendliness, non-toxicity and safe for human. Stable AgNPs were synthesized by treating 90 mL aqueous solution of 2 mM AgNO₃ with the 5 mL plant peels extract (0.4% w/v) at different NaOH concentration (5 mL). The synthesized AgNPs were characterized by UV-Vis spectroscopy, TEM and SEM. Further, antimicrobial activities of AgNPs were performed on Gram positive i.e. Staphylococcus aureus, Bacillus subtilius and Gram negative i.e. E. coli, Pseudomonas aeruginosa bacteria. The AgNPs synthesized at 1.5 mM NaOH concentration had shown maximum zone of inhibition (ZOI) i.e. 49 ± 0.64 in E. coli, whereas Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilius had shown 40 ± 0.29 mm, 28 ± 0.13 and 42 ± 0.49 mm ZOI respectively. The MIC value of 30 μg/mL observed for E. coli Whereas, Staphylococcus aureus, Bacillus subtilius and Pseudomonas aeruginosa had shown 45 μg/mL, 38 μg/mL, 35 μg/mL respectively. The study revealed that AgNPs had shown significant antimicrobial activity as compared to Streptomycin.

  15. Piezoresistive Sensor with High Elasticity Based on 3D Hybrid Network of Sponge@CNTs@Ag NPs.

    PubMed

    Zhang, Hui; Liu, Nishuang; Shi, Yuling; Liu, Weijie; Yue, Yang; Wang, Siliang; Ma, Yanan; Wen, Li; Li, Luying; Long, Fei; Zou, Zhengguang; Gao, Yihua

    2016-08-31

    Pressure sensors with high elasticity are in great demand for the realization of intelligent sensing, but there is a need to develope a simple, inexpensive, and scalable method for the manufacture of the sensors. Here, we reported an efficient, simple, facile, and repeatable "dipping and coating" process to manufacture a piezoresistive sensor with high elasticity, based on homogeneous 3D hybrid network of carbon nanotubes@silver nanoparticles (CNTs@Ag NPs) anchored on a skeleton sponge. Highly elastic, sensitive, and wearable sensors are obtained using the porous structure of sponge and the synergy effect of CNTs/Ag NPs. Our sensor was also tested for over 2000 compression-release cycles, exhibiting excellent elasticity and cycling stability. Sensors with high performance and a simple fabrication process are promising devices for commercial production in various electronic devices, for example, sport performance monitoring and man-machine interfaces.

  16. Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Daima, Hemant K.; Selvakannan, P. R.; Kandjani, Ahmad E.; Shukla, Ravi; Bhargava, Suresh K.; Bansal, Vipul

    2013-12-01

    We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPsY) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation

  17. Mildly reduced graphene oxide-Ag nanoparticle hybrid films for surface-enhanced Raman scattering

    PubMed Central

    2012-01-01

    Large-area mildly reduced graphene oxide (MR-GO) monolayer films were self-assembled on SiO2/Si surfaces via an amidation reaction strategy. With the MR-GO as templates, MR-GO-Ag nanoparticle (MR-GO-Ag NP) hybrid films were synthesized by immersing the MR-GO monolayer into a silver salt solution with sodium citrate as a reducing agent under UV illumination. SEM image indicated that Ag NPs with small interparticle gap are uniformly distributed on the MR-GO monolayer. Raman spectra demonstrated that the MR-GO monolayer beneath the Ag NPs can effectively quench the fluorescence signal emitted from the Ag films and dye molecules under laser excitation, resulting in a chemical enhancement (CM). The Ag NPs with narrow gap provided numerous hot spots, which are closely related with electromagnetic mechanism (EM), and were believed to remarkably enhance the Raman signal of the molecules. Due to the co-contribution of the CM and EM effects as well as the coordination mechanism between the MR-GO and Ag NPs, the MR-GO-Ag NP hybrid films showed more excellent Raman signal enhancement performance than that of either Ag films or MR-GO monolayer alone. This will further enrich the application of surface-enhanced Raman scattering in molecule detection. PMID:22471923

  18. Electroactive Au@Ag nanoparticles driven electrochemical sensor for endogenous H2S detection.

    PubMed

    Zhao, Yuan; Yang, Yaxin; Cui, Linyan; Zheng, Fangjie; Song, Qijun

    2018-05-26

    In this work, a novel and facile electrochemical sensor is reported for the highly selective and sensitive detection of dissolved hydrogen sulfide (H 2 S), attributing to the redox reaction between Au@Ag core-shell nanoparticles (Au@Ag NPs) and H 2 S. Electroactive Au@Ag NPs not only possess excellent conductivity, but exhibit great electrochemical reactivity at 0.26 V due to the electrochemical oxidation from Ag° to Ag + . In the presence of H 2 S, the Ag shell of Au@Ag NPs can be oxidized to Ag 2 S, resulting in the decrease of differential pulse voltammetry (DPV) peak at 0.26 V. The electrochemical sensor exhibits a wide linear response range from 0.1 nM to 500 nM. The limit of detection (LOD) for H 2 S is as low as 0.04 nM. The developed sensor shows significant prospects in the study of pathological processes related to the mechanism of H 2 S production. Copyright © 2018. Published by Elsevier B.V.

  19. Nanoparticle fouling and its combination with organic fouling during forward osmosis process for silver nanoparticles removal from simulated wastewater

    NASA Astrophysics Data System (ADS)

    Zhao, Yanxiao; Wang, Xinhua; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-05-01

    The increasing and wide application of silver nanoparticles (Ag NPs) has resulted in their appearance in wastewater. In consideration of their potential toxicity and environmental impacts, it is necessary to find effective technology for their removal from wastewater. Here, forward osmosis (FO) membrane was applied for Ag NPs removal from wastewater, and single and combined fouling of nanoparticles and organic macromolecules were further investigated during the FO process. The findings demonstrated that FO membrane can effectively remove Ag NPs from wastewater due to its high rejection performance. Fouling tests indicated that water flux declined appreciably even at the beginning of the single Ag NPs fouling test, and more remarkable flux decline and larger amounts of deposited Ag NPs were observed with an increase of Ag NPs concentration. However, the addition of bovine serum albumin (BSA) could effectively alleviate the FO membrane fouling induced by Ag NPs. The interaction between Ag NPs and BSA was responsible for this phenomenon. BSA can easily form a nanoparticle-protein corona surrounded nanoparticles, which prevented nanoparticles from aggregation due to the steric stabilization mechanism. Furthermore, the interaction between BSA and Ag NPs occurred not only in wastewater but also on FO membrane surface.

  20. Ag nanoparticles loading of polypyrrole-coated superwetting mesh for on-demand separation of oil-water mixtures and catalytic reduction of aromatic dyes.

    PubMed

    Yihan, Sun; Mingming, Liu; Guo, Zhiguang

    2018-05-19

    Herein, a catalytic mesh with unique wettability, high oil-water separation efficiency and excellent catalytic performance towards aromatic dyes was fabricated. Polypyrrole (PPy) was firstly pre-coated on pristine stainless-steel mesh (SSM) surface via cyclic voltammetry approach. Subsequently, a simple electrodeposition process was performed to prepare and anchor Ag nanoparticles (AgNPs) onto the PPy-coated SSM surface. The PPy-coated mesh with anchored AgNPs was denoted as PPy/AgNPs-coated SSM. The obtained PPy/AgNPs-coated SSM exhibited dual superlyophobic properties and were able to achieve on-demand separation to deal with various of light oil (ρ oil  < ρ water ) and heavy oil (ρ oil  > ρ water )-water mixtures. Importantly, benefitting from AgNPs on mesh surface, the obtained PPy/AgNPs-coated SSM exhibits exceptional catalytic activity. As proof-of-concept three typical aromatic dye molecules (methylene blue, rhodamine B and Congo red) can be effectivity degraded. Additionally, the degradation of aromatic dyes and oil-water separation were achieved simultaneously when the PPy/AgNPs-coated SSM was converted to water-removing mode. Therefore, the present work is of great significance to the development of novel oil-water filtration membranes and can open a new avenue towards the practicability of metal nanoparticle catalysts in wastewater treatment. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. Preparation of Rh/Ag bimetallic nanoparticles as effective catalyst for hydrogen generation from hydrolysis of KBH4

    NASA Astrophysics Data System (ADS)

    Huang, Liang; Jiao, Chengpeng; Wang, Liqiong; Huang, Zili; Liang, Feng; Liu, Simin; Wang, Yuhua; Zhang, Haijun; Zhang, Shaowei

    2018-01-01

    ISOBAM-104 protected Rh/Ag bimetallic nanoparticles (NPs) with average diameter less than 3.0 nm were synthesized by a co-reduction method. Ultraviolet-visible spectroscopy, transmission electron microscopy (TEM), high-resolution TEM and x-ray photoelectron spectroscopy (XPS) were employed to characterize the structure, particle size, and electronic structure of the prepared bimetallic NPs. The catalytic activities of prepared bimetallic NPs for hydrogen generation from hydrolysis of a basic KBH4 solution were evaluated in detail. The results indicated that as-prepared Rh/Ag bimetallic NPs showed a higher catalytic activity than corresponding monometallic NPs. Among all the monometallic NPs and bimetallic NPs, Rh80Ag20 bimetallic NPs exhibited the highest catalytic activity with a value of 6010 mol-H2·h-1·mol-catalyst-1 at pH = 12 and 303 K. The high catalytic activities of Rh/Ag bimetallic NPs could be attributed to presence of negatively charged Rh atoms and positively charged Ag atoms, which is supported by the results of XPS and density functional theory calculation. Based on the kinetic study, the apparent activation energy for the hydrolysis reaction of the basic KBH4 solution catalyzed by Rh80Ag20 bimetallic NPs was about 47.0 ± 3.9 kJ mol-1.

  2. Red light emitting nano-PVP fibers that hybrid with Ag@SiO2@Eu(tta)3phen-NPs by electrostatic spinning method

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaolin; Tang, Jianguo; Li, Haidong; Wang, Yao; Wang, Xinzhi; Wang, Yanxin; Huang, Linjun; Belfiore, Laurence A.

    2018-04-01

    This work demonstrated red light emitting nano-PVP fibers that incorporated with novel three-layer nanostructure of Ag@SiO2@Eu(tta)3phen nanoparticles (Ag@SiO2@Eu(tta)3phen-NPs), and the hybrid nano-PVP fibers were fabricated via a remarkably simple electrostatic spinning method. For Ag@SiO2@Eu(tta)3phen-NPs, the thickness of SiO2 is optimized to obtain the maximum luminescent intensity, as results, the optimized thickness of SiO2 is 20 nm. And the corresponding luminescent intensity (612 nm) of the Ag@SiO2@Eu(tta)3phen-NPs is enhanced up to 10 times compared with the pure Eu(tta)3phen complex, which indicates that with 20 nm SiO2 thickness, the localized surface plasmon resonance (LSPR) effect of Ag@SiO2 exhibits highest performance for enhancing luminescence. Moreover, the luminescent PVP fibers emit bright red light under the fluorescence microscope, which definitely confirms that the microenvironment provided by PVP polymer is absolutely suitable for the fluorescent composites.

  3. Size-dependent melting modes and behaviors of Ag nanoparticles: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Liang, Tianshou; Zhou, Dejian; Wu, Zhaohua; Shi, Pengpeng

    2017-12-01

    The size-dependent melting behaviors and mechanisms of Ag nanoparticles (NPs) with diameters of 3.5-16 nm were investigated by molecular dynamics (MD). Two distinct melting modes, non-premelting and premelting with transition ranges of about 7-8 nm, for Ag NPs were demonstrated via the evolution of distribution and transition of atomic physical states during annealing. The small Ag NPs (3.5-7 nm) melt abruptly without a stable liquid shell before the melting point, which is characterized as non-premelting. A solid-solid crystal transformation is conducted through the migration of adatoms on the surface of Ag NPs with diameters of 3.5-6 nm before the initial melting, which is mainly responsible for slightly increasing the melting point of Ag NPs. On the other hand, surface premelting of Ag NPs with diameters of 8-16 nm propagates from the outer shell to the inner core with initial anisotropy and late isotropy as the temperature increases, and the close-packed facets {111} melt by a side-consumed way which is responsible for facets {111} melting in advance relative to the crystallographic plane {111}. Once a stable liquid shell is formed, its size-independent minimum thickness is obtained, and a three-layer structure of atomic physical states is set up. Lastly, the theory of point defect-pair (vacancy-interstitial) severing as the mechanism of formation and movement of the solid-liquid interface was also confirmed. Our study provides a basic understanding and theoretical guidance for the research, production and application of Ag NPs.

  4. Synergistic influence of polyoxometalate surface corona towards enhancing the antibacterial performance of tyrosine-capped Ag nanoparticles.

    PubMed

    Daima, Hemant K; Selvakannan, P R; Kandjani, Ahmad E; Shukla, Ravi; Bhargava, Suresh K; Bansal, Vipul

    2014-01-21

    We illustrate a new strategy to improve the antibacterial potential of silver nanoparticles (AgNPs) by their surface modification with the surface corona of biologically active polyoxometalates (POMs). The stable POM surface corona was achieved by utilising zwitterionic tyrosine amino acid as a pH-switchable reducing and capping agent of AgNPs. The general applicability of this approach was demonstrated by developing surface coronas of phosphotungstic acid (PTA) and phosphomolybdic acid (PMA) around AgNPs. Our investigations on Gram negative bacterium Escherichia coli demonstrate that in conjugation with AgNPs, the surface corona of POMs enhances the physical damage to the bacterial cells due to synergistic antibacterial action of AgNPs and POMs, and the ability of tyrosine-reduced AgNPs (AgNPs(Y)) to act as an excellent carrier and stabiliser for the POMs. The further extension of this study towards Gram positive bacterium Staphylococcus albus showed a similar toxicity pattern, whereas these nanomaterials were found to be biocompatible for PC3 epithelial mammalian cells, suggesting the potential of these materials towards specific antimicrobial targeting for topical wound healing applications. The outcomes of this work show that facile tailorability of nanostructured surfaces may play a considerable role in controlling the biological activities of different nanomaterials.

  5. Pathway and mechanism of nitrogen transformation during composting: Functional enzymes and genes under different concentrations of PVP-AgNPs.

    PubMed

    Zeng, Guangming; Zhang, Lihua; Dong, Haoran; Chen, Yaoning; Zhang, Jiachao; Zhu, Yuan; Yuan, Yujie; Xie, Yankai; Fang, Wei

    2018-04-01

    Polyvinylpyrrolidone coated silver nanoparticles (PVP-AgNPs) were applied at different concentrations to reduce total nitrogen (TN) losses and the mechanisms of nitrogen bio-transformation were investigated in terms of the nitrogen functional enzymes and genes. Results showed that mineral N in pile 3 which was treated with AgNPs at a concentration of 10 mg/kg compost was the highest (6.58 g/kg dry weight (DW) compost) and the TN loss (47.07%) was the lowest at the end of composting. Correlation analysis indicated that TN loss was significantly correlated with amoA abundance. High throughput sequencing showed that the dominant family of ammonia-oxidizing bacteria (AOB) was Nitrosomonadaceae, and the number of Operational Taxonomic Units (OTUs) reduced after the beginning of composting when compared with day 1. In summary, treatment with AgNPs at a concentration of 10 mg/kg compost was considerable to reduce TN losses and reserve more mineral N during composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Large enhancement of UV luminescence emission of ZnO nanoparticles by coupling excitons with Ag surface plasmons

    NASA Astrophysics Data System (ADS)

    Kuiri, Probodh K.; Pramanik, Subhamay

    2018-04-01

    For an emitter based on bandgap emission, defect mediated emission has always been considered as the most important loss. Here, a novel approach which can overcome such emission loss is proposed using films of ZnO nanoparticles (NPs) on Ag NPs embedded in silica. The effects of the size of Ag NPs on the enhancement of ultra-violet (UV) photoluminescence (PL) of ZnO NPs for such a system have been studied. For the ZnO NPs without Ag NPs, two emission bands have been seen: one in the UV region and the other one in the visible region. This UV PL emission intensity has been seen to increase significantly with a drastic reduction of the visible PL emission intensity in the case of the sample containing ZnO NPs on silica embedded Ag NPs. A linear increase in UV emission with increase in the size of Ag NPs has been found. For the largest size of Ag NPs (˜10 nm, considered in the present study), the PL emission enhancement becomes about 4 times higher than that of sample without Ag NPs. The observed enhancement of the UV PL emission was caused by coupling between spontaneous emission in ZnO and surface plasmons of Ag. The larger Ag NPs provided a larger scattering cross section in coupling surface plasmons to light leading to an increase in UV emission. Thus, it is possible to convert the useless defect emission to the useful excitonic emission with a large enhancement factor.

  7. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

    PubMed Central

    Hsueh, Yi-Huang; Lin, Kuen-Song; Ke, Wan-Ju; Hsieh, Chien-Te; Chiang, Chao-Lung; Tzou, Dong-Ying; Liu, Shih-Tung

    2015-01-01

    The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation. PMID:26669836

  8. FRET based integrated pyrene-AgNPs system for detection of Hg (II) and pyrene dimer: Applications to environmental analysis

    NASA Astrophysics Data System (ADS)

    Walekar, Laxman S.; Hu, Peidong; Vafaei Molamahmood, Hamed; Long, Mingce

    2018-06-01

    The integrated system of pyrene and cetyltrimethyl ammonium bromide (CTAB) capped silver nanoparticles (AgNPs) with a distance (r) of 2.78 nm has been developed for the detection of Hg (II) and pyrene dimer. The interaction between pyrene and AgNPs results in the fluorescence quenching of pyrene due to the energy transfer, whose mechanism can be attributed to the Forster Resonance Energy Transfer (FRET) supported by experimental observation and theoretical calculations. The developed probe shows a highly selective and sensitive response towards Hg (II) probably due to the amalgam formation, which results in the fluorescence recovery (90%) of pyrene and color change of solution from yellowish brown to colorless. The addition of Hg (II) may increase the distance between pyrene and AgNPs undergoes the 'FRET OFF' process. This system gives a selective response towards Hg (II) over other competing metal ions. Under the optimal condition, the system offers good linearity between 0.1 and 0.6 μg mL-1 with a detection limit of 62 ng mL-1. In addition, the system also provides an effective platform for detection of pyrene in its dimer form even at very low concentrations (10 ng mL-1) on the surface of AgNPs. Therefore, it could be used as effective alternatives for the detection of Hg (II) as well as pyrene simultaneously.

  9. Autoclave mediated one-pot-one-minute synthesis of AgNPs and Au-Ag nanocomposite from Melia azedarach bark extract with antimicrobial activity against food pathogens.

    PubMed

    Pani, Alok; Lee, Joong Hee; Yun, Soon-Ii

    2016-01-01

    The increasing use of nanoparticles and nanocomposite in pharmaceutical and processed food industry have increased the demand for nontoxic and inert metallic nanostructures. Chemical and physical method of synthesis of nanostructures is most popular in industrial production, despite the fact that these methods are labor intensive and/or generate toxic effluents. There has been an increasing demand for rapid, ecofriendly and relatively cheaper synthesis of nanostructures. Here, we propose a strategy, for one-minute green synthesis of AgNPs and a one-pot one-minute green synthesis of Au-Ag nanocomposite, using Melia azedarach bark aqueous extract as reducing agent. The hydrothermal mechanism of the autoclave technology has been successfully used in this study to accelerate the nucleation and growth of nano-crystals. The study also presents high antimicrobial potential of the synthesized nano solutions against common food and water born pathogens. The multistep characterization and analysis of the synthesized nanomaterial samples, using UV-visible spectroscopy, ICP-MS, FT-IR, EDX, XRD, HR-TEM and FE-SEM, also reveal the reaction dynamics of AgNO3, AuCl3 and plant extract in synthesis of the nanoparticles and nanocomposite. The antimicrobial effectiveness of the synthesized Au-Ag nanocomposite, with high gold to silver ratio, reduces the dependency on the AgNPs, which is considered to be environmentally more toxic than the gold counterpart. We hope that this new strategy will change the present course of green synthesis. The rapidity of synthesis will also help in industrial scale green production of nanostructures using Melia azedarach.

  10. Antimicrobial activity of silver nanoparticles encapsulated in poly-N-isopropylacrylamide-based polymeric nanoparticles.

    PubMed

    Qasim, Muhammad; Udomluck, Nopphadol; Chang, Jihyun; Park, Hansoo; Kim, Kyobum

    2018-01-01

    In this study, we analyzed the antimicrobial activities of poly- N -isopropylacrylamide (pNIPAM)-based polymeric nanoparticles encapsulating silver nanoparticles (AgNPs). Three sizes of AgNP-encapsulating pNIPAM- and pNIPAM-NH 2 -based polymeric nanoparticles were fabricated. Highly stable and uniformly distributed AgNPs were encapsulated within polymeric nanoparticles via in situ reduction of AgNO 3 using NaBH 4 as the reducing agent. The formation and distribution of AgNPs was confirmed by UV-visible spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometry, respectively. Both polymeric nanoparticles showed significant bacteriostatic activities against Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria depending on the nanoparticle size and amount of AgNO 3 used during fabrication.

  11. Antimicrobial activity of silver nanoparticles encapsulated in poly-N-isopropylacrylamide-based polymeric nanoparticles

    PubMed Central

    Qasim, Muhammad; Udomluck, Nopphadol; Chang, Jihyun; Park, Hansoo; Kim, Kyobum

    2018-01-01

    In this study, we analyzed the antimicrobial activities of poly-N-isopropylacrylamide (pNIPAM)-based polymeric nanoparticles encapsulating silver nanoparticles (AgNPs). Three sizes of AgNP-encapsulating pNIPAM- and pNIPAM-NH2-based polymeric nanoparticles were fabricated. Highly stable and uniformly distributed AgNPs were encapsulated within polymeric nanoparticles via in situ reduction of AgNO3 using NaBH4 as the reducing agent. The formation and distribution of AgNPs was confirmed by UV-visible spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometry, respectively. Both polymeric nanoparticles showed significant bacteriostatic activities against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria depending on the nanoparticle size and amount of AgNO3 used during fabrication. PMID:29379284

  12. As-synthesis of nanostructure AgCl/Ag/MCM-41 composite

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Pourahmad, A.

    2012-02-01

    In this work, we present the simple synthetic route for silver chloride/silver nanoparticles (AgCl/Ag-NPs) using as-synthesis method. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed that when AgNO 3 content is below 0.1 wt.% in synthetic gel, the guest AgCl/Ag-NPs is formed on the silica channel wall, and lower exists in the crystalline state. When AgNO 3 content exceeds this value, AgCl/Ag nanoparticles can be observed in high crystalline state. The absorption at 327 nm ascribed to the characteristic absorption of the AgCl semiconductor. Ag nanoparticles have been shown to exist in the nanocomposite at 375 nm. When AgNO 3 content is above 0.1 wt.% in synthetic gel, spectra exhibited stronger absorption at 450-700 nm that was attributed to the surface plasmonic resonance of silver nanoparticles. The obtained AgCl/Ag/MCM-41 sample exhibit enhanced photocatalytic activity for the degradation of methylene blue under visible-light irradiation.

  13. Immobilized Pd-Ag bimetallic nanoparticles on polymeric nanofibers as an effective catalyst: effective loading of Ag with bimetallic functionality through Pd nucleated nanofibers.

    PubMed

    Ranjith, Kugalur Shanmugam; Celebioglu, Asli; Uyar, Tamer

    2018-06-15

    Here, we present a precise process for synthesizing Pd-Ag bimetallic nanoparticles (NPs) onto polymeric nanofibers by decorating Pd-NPs through atomic layer deposition followed by a chemical reduction process for tagging Ag nanostructures with bimetallic functionality. The results show that Pd-NPs act as a nucleation platform for tagging Ag and form Pd-Ag bimetallic NPs with a monodisperse nature with significant catalytic enhancement to the reaction rate over the bimetallic nature of the Pd-Ag ratio. A Pd-NP decorated polymeric nanofibrous web acts as an excellent platform for the encapsulation or interaction of Ag, which prevents agglomeration and promotes the interaction of Ag ions only on the surface of the Pd-NPs. We observed an effective reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH 4 ) to access the catalytic activity of Pd-Ag bimetallic NPs on a free-standing flexible polymeric nanofibrous web as a support. The captive formation of the polymeric nanofibrous web with Pd-Ag bimetallic functionality exhibited superior and stable catalytic performance with reduction rates of 0.0719, 0.1520, and 0.0871 min -1 for different loadings of Ag on Pd decorated nanofibrous webs such as Pd/Ag(0.01), Pd/Ag(0.03), and Pd/Ag(0.05), respectively. The highly faceted Pd-Ag NPs with an immobilized nature improves the catalytic functionality by enhancing the binding energy of the 4-NP adsorbate to the surface of the NPs. With the aid of bimetallic functionality, the nanofibrous web was demonstrated as a hybrid heterogeneous photocatalyst with a 3.16-fold enhancement in the reaction rate as compared with the monometallic decorative nature of NaBH 4 as a reducing agent. The effective role of the monodisperse nature of Pd ions with an ultralow content as low as 3 wt% and the tunable ratio of Ag on the nanofibrous web induced effective catalytic activity over multiple cycles.

  14. Immobilized Pd-Ag bimetallic nanoparticles on polymeric nanofibers as an effective catalyst: effective loading of Ag with bimetallic functionality through Pd nucleated nanofibers

    NASA Astrophysics Data System (ADS)

    Shanmugam Ranjith, Kugalur; Celebioglu, Asli; Uyar, Tamer

    2018-06-01

    Here, we present a precise process for synthesizing Pd-Ag bimetallic nanoparticles (NPs) onto polymeric nanofibers by decorating Pd-NPs through atomic layer deposition followed by a chemical reduction process for tagging Ag nanostructures with bimetallic functionality. The results show that Pd-NPs act as a nucleation platform for tagging Ag and form Pd-Ag bimetallic NPs with a monodisperse nature with significant catalytic enhancement to the reaction rate over the bimetallic nature of the Pd-Ag ratio. A Pd-NP decorated polymeric nanofibrous web acts as an excellent platform for the encapsulation or interaction of Ag, which prevents agglomeration and promotes the interaction of Ag ions only on the surface of the Pd-NPs. We observed an effective reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4) to access the catalytic activity of Pd-Ag bimetallic NPs on a free-standing flexible polymeric nanofibrous web as a support. The captive formation of the polymeric nanofibrous web with Pd-Ag bimetallic functionality exhibited superior and stable catalytic performance with reduction rates of 0.0719, 0.1520, and 0.0871 min‑1 for different loadings of Ag on Pd decorated nanofibrous webs such as Pd/Ag(0.01), Pd/Ag(0.03), and Pd/Ag(0.05), respectively. The highly faceted Pd-Ag NPs with an immobilized nature improves the catalytic functionality by enhancing the binding energy of the 4-NP adsorbate to the surface of the NPs. With the aid of bimetallic functionality, the nanofibrous web was demonstrated as a hybrid heterogeneous photocatalyst with a 3.16-fold enhancement in the reaction rate as compared with the monometallic decorative nature of NaBH4 as a reducing agent. The effective role of the monodisperse nature of Pd ions with an ultralow content as low as 3 wt% and the tunable ratio of Ag on the nanofibrous web induced effective catalytic activity over multiple cycles.

  15. Green synthesis of Pt and Ag nanoparticles and their use towards nitric oxide abatement

    NASA Astrophysics Data System (ADS)

    Castegnaro, Marcus V.; Alexandre, Jéssica; Baibich, Ione M.; Alves, Maria C. M.; Morais, Jonder

    2014-12-01

    Pt and Ag nanoparticles (NPs) were synthesized by eco-friendly room-temperature chemical reduction routes based on trisodium citrate and L-ascorbic acid (for Pt NPs) and on gelatin and trisodium citrate (for Ag NPs). The as-prepared NPs were characterized by UV-visible absorption spectroscopy and transmission electron microscopy analyses, which confirmed the formation of sub-10 nm metal particles. Then, the colloidal solutions were used to obtain activated carbon-supported catalysts (metal/AC) for direct NO decomposition. X-ray photoelectron spectroscopy and x-ray diffraction measurements proved that the NPs hosted on the support surface were present in the metallic chemical state. In situ infrared absorption spectroscopy investigations during NO reduction catalytic reactions showed that the Pt/AC and Ag/AC catalysts were highly active at 373 K. At 573 K, we observed different behaviors for each catalyst. While Ag/AC performed similarly to the reaction at 373 K, Pt/AC was found to participate in a redox mechanism, where the catalyst’s active sites were oxidized by NO and reduced by carbon, thus emitting CO2 and enhancing its catalytic activity, an effect that we have also observed in carbon-supported Pd NPs.

  16. Homogeneous synthesis of Ag nanoparticles-doped water-soluble cellulose acetate for versatile applications.

    PubMed

    Cao, Jie; Sun, Xunwen; Zhang, Xinxing; Lu, Canhui

    2016-11-01

    We report a facile and efficient approach for synthesis of well-dispersed and stable silver nanoparticles (Ag NPs) using water-soluble cellulose acetate (CA) as both reductant and stabilizer. Partially substituted CA with highly active hydroxyl groups and excellent water-solubility is able to reduce silver ions in homogeneous aqueous medium effectively. The synthesized Ag NPs were characterized by UV-vis spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and energy dispersive X-ray spectroscope analysis. The as-prepared Ag NPs were well-dispersed, showing a surface plasmon resonance peak at 426nm. The resulted Ag NPs@CA nanohybrids exhibit high catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH 4 . Meanwhile, the nanohybrids are also effective in inhibiting the growth of bacterial. This environmentally friendly method promotes the use of renewable natural resources to prepare a variety of inorganic-organic materials for catalysis, antibacterial, sensors and other applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Anaerobic Toxicity of Cationic Silver Nanoparticles | Science ...

    EPA Pesticide Factsheets

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNps) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10-15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L-1, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L-1 as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag+. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L-1 as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. The current

  18. Frequency upconversion in Er3+ doped tungsten tellurite glass containing Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Mahajan, S. K.; Parashar, J.

    2018-05-01

    The frequency upconversion emission in Er3+ doped TeO2-WO3-Li2O containing Ag nanoparticle (TWLEOAG) glasses at 980nm excitation is reported. The absorption spectra reveal not only the peaks due to Er3+ ions, but also the surface plasmon resonance band of silver NPs located around 525nm and 650 nm. The spherical AgNPs with average size ˜38 nm in the glassy matrix is evidenced from the TEM measurement. Under 980nm laser excitation upconversion emission spectra show two major emission at 550nm and 638nm originating from 4S3/2 and 4F9/2 energy levels of the Er3+ ions, respectively was observed. Upconversion emission enhancement factor 7 fold has been measured for sample heat treated during 40h. However for 18h heat treated TWLEOAG sample under 980 nm flash lamp excitation produced Intense green compare to red emission. Since the 980nm frequency is far from the AgNPs surface plasmon resonance frequency, visible emission ehancement is attributed to local field increase in proximity of the Ag NPs and not energy tranfer from NPs to emitters. Possible energy transfer upconversion mechanism has been also discussed.

  19. Graphene oxide-Ag nanoparticles-pyramidal silicon hybrid system for homogeneous, long-term stable and sensitive SERS activity

    NASA Astrophysics Data System (ADS)

    Guo, Jia; Xu, Shicai; Liu, Xiaoyun; Li, Zhe; Hu, Litao; Li, Zhen; Chen, Peixi; Ma, Yong; Jiang, Shouzhen; Ning, Tingyin

    2017-02-01

    In our work, few layers graphene oxide (GO) were directly synthesized on Ag nanoparticles (AgNPs) by spin-coating method to fabricate a GO-AgNPs hybrid structure on a pyramidal silicon (PSi) substrate for surface-enhanced Raman scattering (SERS). The GO-AgNPs-PSi substrate showed excellent Raman enhancement effect, the minimum detected concentration for Rhodamine 6G (R6G) can reach 10-12 M, which is one order of magnitude lower than the AgNPs-PSi substrate and two order of magnitude lower than the GO-AgNPs-flat-Si substrate. The linear fit calibration curve with error bars is presented and the value of R2 of 612 and 773 cm-1 can reach 0.986 and 0.980, respectively. The excellent linear response between the Raman intensity and R6G concentrations prove that the prepared GO-AgNPs-PSi substrates can serve as good SERS substrate for molecule detection. The maximum deviations of SERS intensities from 20 positions of the GO-AgNPs-PSi substrate are less than 8%, revealing the high homogeneity of the SERS substrate. The excellent homogeneity of the enhanced Raman signals can be attributed to well-separated pyramid arrays of PSi, the uniform morphology of AgNPs and multi-functions of GO layer. Besides, the uniform GO film can effectively protect AgNPs from oxidation and endow the hybrid system a good stability and long lifetime. This GO-AgNPs-PSi substrate may provide a new way toward practical applications for the ultrasensitive and label-free SERS detection in areas of medicine, food safety and biotechnology.

  20. Core-shell AgSiO2-protoporphyrin IX nanoparticle: Effect of the Ag core on reactive oxygen species generation

    NASA Astrophysics Data System (ADS)

    Lismont, M.; Pá; ez-Martinez, C.; Dreesen, L.

    2015-03-01

    Photodynamic therapy (PDT) for cancer is based on the use of a light sensitive molecule to produce, under specific irradiation, toxic reactive oxygen species (ROS). A way to improve the therapy efficiency is to increase the amount of produced ROS near cancer cells. This aim can be achieved by using a metal enhanced process arising when an optically active molecule is located near a metallic nanoparticle (NP). Here, the coupling effect between silver (Ag) NPs and protoporphyrin IX (PpIX) molecules, a clinically approved photosensitizer, is studied compared first, to PpIX fluorescence yield and second, to ROS production efficiency. By applying a modified Stöber process, PpIX was encapsulated into a silica (SiO2) shell, surrounding a 60 nm sized Ag core. We showed that, compared to SiO2-PpIX NPs, Ag coated SiO2-PpIX NPs dramatically decreased PpIX fluorescence together with singlet oxygen production efficiency. However, after incubation time in the dark, the amount of superoxide anions generated by the Ag doped sample was higher than the control sample one.

  1. Modification of the internal surface of photonic crystal fibers with Ag and Au nanoparticles for application as sensor elements

    NASA Astrophysics Data System (ADS)

    Pidenko, Pavel S.; Borzov, Victor M.; Savenko, Olga A.; Skaptsov, Alexander A.; Skibina, Yulia S.; Goryacheva, Irina Yu.; Rusanova, Tatiana Yu.

    2017-03-01

    Photonic crystal fibers (PCFs) are one of the most promising materials for biosensors construction due to their unique optical properties. The modification of PCF by noble metal nanoparticles (NPs) provides the SPR and SERS signal detection where as the application amino group-containing compounds allows efficient binding of biomolecules. In this work the internal surface of glass hollow core photonic crystal fibers (HC-PCFs) has been modified Ag and Au nanoparticles using three different approaches. PCFs were treated by: 1) mixture of NPs and precursors for silanization (tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES)); 2) alternately deposition of polyelectrolytes and NPs, 3) mixture of chitosan with NPs. The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of NPs on the HC-PCF inner surface. The most efficient techniques were the chitosan application for Ag NPs and silanization for Au NPs. The obtaining PCFs could be useful for creating biosensitive elements.

  2. Biosynthesis of Ag nanoparticles using Salicornia bigelovii and its antibacterial activity.

    PubMed

    Khatami, Mehrdad; Noor, Fatemeh Golshan; Ahmadi, Saeed; Aflatoonian, Mohammadreza

    2018-04-01

    In recent years, the field of nanotechnology has become the most active area of research in modern material science. While many chemical- as well as physical methods are also used, green synthesis of nanoparticles is becoming the most evolved method of synthesis. In this study, we synthesized silver nanoparticles from the seed extract of Salicornia bigelovii. This experimental study was conducted from December 2017 to January 2018 in Kerman University of Medical Sciences, Kerman, Iran. The effects of two concentrations (1m M and 4mM) on the synthesis of nanoparticles were studied. Characterizations were done using different methods including ultraviolet (UV) visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Antibacterial activity of Ag nanoparticles against Staphylococcus aureus and Escherichia coli was studied using microdilution method. The data were analyzed using Probit test in SPSS (Version 20, USA). Formation of the AgNPs was confirmed by surface plasmon spectra using UV-Vis spectrophotometer and absorbance peaks at 434 nm. The FTIR spectra showed the possible role of the functional group like carbonyl groups in reduction of silver ions to silver nanoparticles. The XRD analysis showed that the synthesized silver nanoparticles are of face-centered cubic structure. The TEM showed the formation of silver nanoparticles ranging in diameter from 1 to 50 nm. The minimal inhibitory concentration and minimal bactericidal concentration of AgNPs were determined for both S. aureus and E. coli 6.25 and 12.5 μg/mL, respectively. An environmentally friendly approach is more affordable than chemical methods. Physicochemical approaches can be harmful to the environment and to human health. Thus, the green synthesis methods are simple, less expensive, and can cut consumption of energy; they can be used for synthesis of fixed nanoparticles with preferred shape and size, without the use of

  3. Phytosynthesis of stable Au, Ag and Au-Ag alloy nanoparticles using J. Sambac leaves extract, and their enhanced antimicrobial activity in presence of organic antimicrobials

    NASA Astrophysics Data System (ADS)

    Yallappa, S.; Manjanna, J.; Dhananjaya, B. L.

    2015-02-01

    A green chemistry approach for the synthesis of Au, Ag and Au-Ag alloy nanoparticles (NPs) using the corresponding metal precursors and Jasminum sambac leaves extract as both reducing and capping media, under microwave irradiation, is reported. During the formation, as expected, the reaction mixture shows marginal decrease in pH and an increase in solution potential. The formation of NPs is evident from their surface plasmon resonance (SPR) peak observed at ∼555 nm for Au, ∼435 nm for Ag and ∼510 nm for Au-Ag alloy. The XRD pattern shows fcc structure while the FTIR spectra indicate the presence of plant residues adsorbed on these NPs. Such a bio-capping of NPs is characterized by their weight loss, ∼35% due to thermal degradation of biomass, as observed in TG analysis. The colloidal dispersion of NPs is stable for about 6 weeks. The near spherical shape of NPs (ϕ20-50 nm) is observed by FE-SEM/TEM images and EDAX gives the expected elemental composition. Furthermore, these NPs showed enhanced antimicrobial activity (∼1-4-fold increase in zone of inhibition) in combination with antimicrobials against test strains. Thus, the phytosynthesized NPs could be used as effective growth inhibitors for various microorganisms.

  4. Ag/CuO nanoparticles prepared from a novel trinuclear compound [Cu(Imdz)4(Ag(CN)2)2] (Imdz = imidazole) by a pyrolysis display excellent antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Adhikary, Jaydeep; Das, Balaram; Chatterjee, Sourav; Dash, Sandeep Kumar; Chattopadhyay, Sourav; Roy, Somenath; Chen, Jeng-Wei; Chattopadhyay, Tanmay

    2016-06-01

    One copper and two silver containing one hetero tri-nuclear precursor compound [Cu(Imdz)4(Ag(CN)2)2] (1) (Imdz = Imidazole) has been synthesized and characterized by single crystal X-ray diffraction. Simple pyrolysis of the complex at 550 °C for 4 h afforded Ag/CuO nanoparticles (NPs). The synthesized nanoparticles were characterized by ultraviolet-visible (UV-Vis), Fourier transform infrared (FT-IR), X-ray powder diffraction (XRPD), dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and X-ray photo electron spectroscopy (XPS). Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) have been employed as model microbial species to study the anti-microbial activity of the synthesized NPs. The NPs showed potent anti-microbial activity evidenced from the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values. Very high level of cell uptake and then generation of reactive oxygen species (ROS) are the origin of such strong antimicrobial activity for the NPs. However, the cytotoxicity level of the NPs towards normal human cell is very low.

  5. Synthesis of gold and silver nanoparticles using purified URAK.

    PubMed

    Deepak, Venkataraman; Umamaheshwaran, Paneer Selvam; Guhan, Kandasamy; Nanthini, Raja Amrisa; Krithiga, Bhaskar; Jaithoon, Nagoor Meeran Hasika; Gurunathan, Sangiliyandi

    2011-09-01

    This study aims at developing a new eco-friendly process for the synthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using purified URAK. URAK is a fibrinolytic enzyme produced by Bacillus cereus NK1. The enzyme was purified and used for the synthesis of AuNPs and AgNPs. The enzyme produced AgNPs when incubated with 1 mM AgNO3 for 24 h and AuNPs when incubated with 1 mM HAuCl4 for 60 h. But when NaOH was added, the synthesis was rapid and occurred within 5 min for AgNPs and 12 h for AuNPs. The synthesized nanoparticles were characterized by a peak at 440 nm and 550 nm in the UV-visible spectrum. TEM analysis showed that AgNPs of the size 60 nm and AuNPs of size 20 nm were synthesized. XRD confirmed the crystalline nature of the nanoparticles and AFM showed the morphology of the nanoparticle to be spherical. FT-IR showed that protein was responsible for the synthesis of the nanoparticles. This process is highly simple, versatile and produces AgNPs and AuNPs in environmental friendly manner. Moreover, the synthesized nanoparticles were found to contain immobilized enzyme. Also, URAK was tested on RAW 264.7 macrophage cell line and was found to be non-cytotoxic until 100 μg/ml. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Role of catalytic protein and stabilising agents in the transformation of Ag ions to nanoparticles by Pseudomonas aeruginosa.

    PubMed

    Ali, Jafar; Hameed, Abdul; Ahmed, Safia; Ali, Muhammad Ishtiaq; Zainab, Shama; Ali, Naeem

    2016-10-01

    Biological routes of synthesising metal nanoparticles (NPs) using microbes have been gaining much attention due to their low toxicity and eco-friendly nature. Pseudomonas aeruginosa JP2 isolated from metal contaminated soil was evaluated towards extracellular synthesis of silver NPs (AgNPs). Cell-free extract (24 h) of the bacterial isolate was reacted with AgNO 3 for 24 h in order to fabricate AgNPs. Preliminary observations were recorded in terms of colour change of the reaction mixture from yellow to greyish black. UV-visible spectroscopy of the reaction mixture has shown a progressive increase in optical densities that correspond to peaks near 430 nm, depicting reduction of ionic silver (Ag + ) to atomic silver (Ag 0 ) thereby synthesising NPs. X-ray diffraction spectra exhibited the 2θ values to be 38.4577° confirming the crystalline and spherical nature of NPs [9.6 - 26.7 (Ave. = 17.2 nm)]. Transmission electron microscopy finally confirmed the size of the particles varying from 5 to 60 nm. Moreover, rhamnolipids and proteins were identified as stabilising molecules for the AgNPs through Fourier transform-infrared spectroscopy. Characterisation of bacterial crude and purified protein fractions confirmed the involvement of nitrate reductase (molecular weight 66 kDa and specific activity = 3.8 U/mg) in the Synthesis of AgNPs.

  7. Facile synthesis of dispersed Ag nanoparticles on chitosan-TiO2 composites as recyclable nanocatalysts for 4-nitrophenol reduction

    NASA Astrophysics Data System (ADS)

    Xiao, Gang; Zhao, Yilin; Li, Linghui; Pratt, Jonathan O.; Su, Haijia; Tan, Tianwei

    2018-04-01

    This paper presents a facile, rapid, and controllable procedure for the recovery of trace Ag+ ions and in situ assembly of well dispersed Ag nanoparticles on chitosan-TiO2 composites through bioaffinity adsorption followed by photocatalytic reduction. The prepared Ag nanoparticles are proven to be efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. Well dispersed quasi-spherical Ag NPs are synthesized in 20 min in the designed inner-irradiated photocatalytic system under a wide range of Ag+ concentrations (50-200 mg l-1), temperatures (10 °C-25 °C) conditions, and UV or visible light irradiation. The synthesized Ag NPs can catalyze the reduction of 4-nitrophenol by NaBH4 at 100% conversion in 120 min and preserve the catalytic activity in five successive cycles. This procedure for trace Ag+ ions recovery and Ag NPs assembly has the potential to be scaled up for the mass production of recyclable Ag nanocatalysts. The present work provides a green and efficient procedure for the conversion of hazardous 4-nitrophenol to industrially important 4-aminophenol and also sheds a light on designing scaled-up procedures for treating high volumes of wastewater with dilute heavy metals to produce recyclable metallic nanocatalysts in aqueous systems.

  8. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Science Inventory

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged p...

  9. On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Mikhlin, Yuri L.; Vorobyev, Sergey A.; Saikova, Svetlana V.; Vishnyakova, Elena A.; Romanchenko, Alexander S.; Zharkov, Sergey M.; Larichev, Yurii V.

    2018-01-01

    Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

  10. Synthesis of Ag and Au nanoparticles embedded in carbon film: Optical, crystalline and topography analysis

    NASA Astrophysics Data System (ADS)

    Gholamali, Hediyeh; Shafiekhani, Azizollah; Darabi, Elham; Elahi, Seyed Mohammad

    2018-03-01

    Atomic force microscopy (AFM) images give valuable information about surface roughness of thin films based on the results of power spectral density (PSD) through the fast Fourier transform (FFT) algorithms. In the present work, AFM data are studied for silver and gold nanoparticles (Ag NPs a-C: H and Au NPs a-C: H) embedded in amorphous hydrogenated carbon films and co-deposited on glass substrate via of RF-Sputtering and RF-Plasma Enhanced Chemical Vapor Deposition methods. Here, the working gas is acetylene and the targets are Ag and Au. While time and power are constant, the only variable parameter in this study is initial pressure. In addition, the crystalline structure of Ag NPs a-C: H and Au NPs a-C: H are studied using X-ray diffraction (XRD). UV-visible spectrophotometry will also investigate optical properties and localized surface plasmon resonance (LSPR) of samples.

  11. Eco-friendly biosynthesis, anticancer drug loading and cytotoxic effect of capped Ag-nanoparticles against breast cancer

    NASA Astrophysics Data System (ADS)

    Naz, M.; Nasiri, N.; Ikram, M.; Nafees, M.; Qureshi, M. Z.; Ali, S.; Tricoli, A.

    2017-11-01

    The work aimed to prepare silver nanoparticles (Ag-NPs) from silver nitrate and various concentrations of the seed extract ( Setaria verticillata) by a green synthetic route. The chemical and physical properties of the resulting Ag-NPs were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry and ultraviolet-visible (UV-Vis) spectrophotometry. Anticancer activity of Ag-NPs (5-20 nm) had dose-dependent cytotoxic effect against breast cancer (MCF7-FLV) cells. The in vitro toxicity was studied on adult earthworms (Lumbricina) resulting in statistically significant ( P < 0.05) inhibition. The prepared NPs were loaded with hydrophilic anticancer drugs (ACD), doxorubicin (DOX) and daunorubicin (DNR), for developing a novel drug delivery carrier having significant adsorption capacity and efficiency to remove the side effects of the medicines effective for leukemia chemotherapy.

  12. A colorimetric assay for measuring iodide using Au@Ag core-shell nanoparticles coupled with Cu(2+).

    PubMed

    Zeng, Jingbin; Cao, Yingying; Lu, Chun-Hua; Wang, Xu-Dong; Wang, Qianru; Wen, Cong-Ying; Qu, Jian-Bo; Yuan, Cunguang; Yan, Zi-Feng; Chen, Xi

    2015-09-03

    Au@Ag core-shell nanoparticles (NPs) were synthesized and coupled with copper ion (Cu(2+)) for the colorimetric sensing of iodide ion (I(-)). This assay relies on the fact that the absorption spectra and the color of metallic core-shell NPs are sensitive to their chemical ingredient and dimensional core-to-shell ratio. When I(-) was added to the Au@Ag core-shell NPs-Cu(2+) system/solution, Cu(2+) can oxidize I(-) into iodine (I2), which can further oxidize silver shells to form silver iodide (AgI). The generated Au@AgI core-shell NPs led to color changes from yellow to purple, which was utilized for the colorimetric sensing of I(-). The assay only took 10 min with a lowest detectable concentration of 0.5 μM, and it exhibited excellent selectivity for I(-) over other common anions tested. Furthermore, Au@Ag core-shell NPs-Cu(2+) was embedded into agarose gels as inexpensive and portable "test strips", which were successfully used for the semi-quantitation of I(-) in dried kelps. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. LSPR Tuning from 470 to 800 nm and Improved Stability of Au-Ag Nanoparticles Formed by Gold Deposition and Rebuilding in the Presence of Poly(styrenesulfonate).

    PubMed

    Cathcart, Nicole; Chen, Jennifer I L; Kitaev, Vladimir

    2018-01-16

    Stability and precise control over functional properties of metal nanoparticles remain a challenge for the realization of prospective applications. Our described process of shell formation and rebuilding can address both these challenges. Template silver nanoparticles (AgNPs) stabilized by poly(styrenesulfonate) are first transformed with gold deposition, after which the resulting shell rebuilds with the replaced silver. The shell formation and rebuilding are accompanied by large shifts in localized surface plasmon resonance (LSPR) peak position, which enables LSPR tuning in a range from 470 to 800 nm. Furthermore, chemical stability of Au-AgNPs is significantly improved compared to AgNPs due to gold stability. Silver templates of different shapes and sizes were demonstrated to transform to AuAg composite NPs to further extend the accessible LSPR range tuning. Stabilization of template AgNPs with poly(styrenesulfonate), in contrast to commonly used poly(vinylpyrrolidone), was found to be a key factor for shell rebuilding. The developed Au-AgNPs were shown to be advantageous for surface plasmon resonance (SPR) detection and surface-enhanced Raman spectroscopy (SERS) owing to their tunable LSPR and enhanced stability.

  14. Infrared light-assisted preparation of Ag nanoparticles-reduced graphene oxide nanocomposites for non-enzymatic H{sub 2}O{sub 2} sensing

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ji, Ye; State Key Laboratory of Transducer Technology, Chinese Academy of Sciences; Zhang, Yong

    2015-12-15

    Graphical abstract: An infrared light irradiation method has been developed for preparation of AgNPs/rGO nanocomposites for electrochemical detection of H{sub 2}O{sub 2}. - Highlights: • AgNPs/rGO nanocomposites have been prepared by photochemical method. • AgNPs/rGO nanocomposites exhibit good sensing performances for detection of H{sub 2}O{sub 2}. • The present work provides a simple and green method for preparation of rGO-based materials. - Abstract: A green method has been developed for preparation of Ag nanoparticles/reduced graphene oxide (AgNPs/rGO) nanocomposites by infrared light irradiation. The characterizations indicate the successful preparation of AgNPs/rGO nanocomposites. Most importantly, AgNPs/rGO nanocomposites exhibit excellent electrocatalytic activity formore » reduction of H{sub 2}O{sub 2}, leading to a high-performance non-enzymatic H{sub 2}O{sub 2} sensor with linear detection range and detection limit about 0.1 mM to 140 mM (r = 0.9896) and 3.0 μM, respectively.« less

  15. Green synthesis and characterization of Ag nanoparticles from Mangifera indica leaves for dental restoration and antibacterial applications.

    PubMed

    Sundeep, Dola; Vijaya Kumar, T; Rao, P S Subba; Ravikumar, R V S S N; Gopala Krishna, A

    2017-05-01

    Green synthesis has gained a wide recognition as clean synthesis technique in the recent years. In the present investigation, silver nanoparticles were prepared by a novel green synthesis technique using Mangifera indica (Mango leaves) and found to be successfully used in dental applications. The prepared samples were spectroscopically characterized by XRD, PSA, SEM with EDS, and UV-Vis spectroscopy. The crystalline size and lattice strain were analyzed from the XRD data which were counter-verified by W-H plots and particle size analyzer. The XRD peaks revealed that average crystalline size of the as-synthesized Ag nanoparticles was of 32.4 nm with face-centered cubic structure. This was counter-verified by particle size analyzer and Williamson-Hall plots and found to be 31.7 and 33.21 nm in the former and latter, and the crystalline size of Ag NPs could be concluded as 32 ± 2 nm. The morphological structure of the prepared sample was studied through SEM images and the chemical composition was analyzed by the EDS data. The band energy was calculated as 393 nm from UV-Vis, which confirmed the synthesized sample as Ag nanoparticles. To improve the mechanical bonding and hardness of the dentally used glass ionomer cement (GIC), the synthesized silver nanoparticles were incorporated into GIC in 2% weight ratio. The morphology of the prepared specimens was studied using optical microscope images. Vickers microhardness and Monsanto hardness tests were performed on GIC, GIC reinforced with microsilver particles and GIC reinforced with nanosilver particles and the latter derived a promising results. The results of the Monsanto tests confirmed the increase in hardness of the GIC reinforced with AgNps as 14.2 kg/cm 2 compared to conventional GIC and GIC reinforced with silver microparticle as 11.7 and 9.5 kg/cm 2 . Similarly the Vickers hardness results exhibited the enhanced hardness of GIC-reinforced AgNps as 82 VHN compared to GIC as 54 and GIC-reinforced silver

  16. Ag-NPs embedded in two novel Zn3/Zn5-cluster-based metal-organic frameworks for catalytic reduction of 2/3/4-nitrophenol.

    PubMed

    Wu, Xue-Qian; Huang, Dan-Dan; Zhou, Zhi-Hang; Dong, Wen-Wen; Wu, Ya-Pan; Zhao, Jun; Li, Dong-Sheng; Zhang, Qichun; Bu, Xianhui

    2017-02-21

    By utilizing symmetrical pentacarboxylate ligands, 3,5-di(2',5'-dicarboxylphenyl)benzoic acid (H 5 L1) and 3,5-di(2',4'-dicarboxylphenyl)benzoic acid (H 5 L2), two novel porous Zn-MOFs, [Zn 5 (μ 3 -H 2 O) 2 (L1) 2 ]·3DMA·4H 2 O (CTGU-3) and [Zn 3 (μ 3 -OH)L2(H 2 O) 3 ]·H 2 O (CTGU-4) have been synthesized under solvothermal conditions. CTGU-3 and CTGU-4 exhibit 3D microporous frameworks with flu and dia topologies and possess unique secondary building units [Zn 5 (μ 3 -H 2 O) 2 (RCO 2 ) 6 ] and [Zn 3 (μ 3 -OH)(RCO 2 ) 3 ], respectively. Such porous systems create a unique space or surface to accommodate Ag nanoparticles (Ag NPs), which could efficiently prevent Ag NPs from aggregation and leaching. In this work, two new Ag@Zn-MOF composites, denoted as Ag@CTGU, have been successfully fabricated through solution infiltration, for the reduction of nitrophenol. Compared with CTGU-4, CTGU-3 shows enhanced catalytic efficiency toward the reaction when it is used as a catalyst support of Ag NPs. Moreover, gas sorption and luminescence properties of two compounds were also investigated.

  17. Enhancement in volatile organic compound sensitivity of aged Ag nanoparticle aggregates by plasma exposure

    NASA Astrophysics Data System (ADS)

    Hosomi, Kei; Ozaki, Koichi; Nishiyama, Fumitaka; Takahiro, Katsumi

    2018-01-01

    Silver nanoparticles (Ag NPs) tarnish easily upon exposure to ambient air, and eventually lose their ability as a plasmonic sensor via weakened localized surface plasmon resonance (LSPR). We have demonstrated the enhancement in plasmonic sensitivity of tarnished Ag NP aggregates to vapors of volatile organic compounds (VOCs) such as ethanol and butanol by Ar plasma exposure. The response of Ag NP aggregates to the VOC vapors was examined by measuring the change in optical extinction spectra before and after exposure to the vapors. The sensitivity of Ag NP aggregates decreased gradually when stored in ambient air. The performance of tarnished Ag NPs for ethanol sensing was recovered by exposure to argon (Ar) plasma for 15 s. The reduction from oxidized Ag to metallic one was recognized, while morphological change was hardly noticeable after the plasma exposure. We conclude, therefore, that a compositional change rather than a morphological change occurred on Ag NP surfaces enhances the sensing ability of tarnished Ag NP aggregates to the VOC vapors.

  18. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-07-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs.

  19. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles.

    PubMed

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-01-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs.

  20. Broadband light absorption enhancement in dye-sensitized solar cells with Au-Ag alloy popcorn nanoparticles

    PubMed Central

    Xu, Qi; Liu, Fang; Liu, Yuxiang; Cui, Kaiyu; Feng, Xue; Zhang, Wei; Huang, Yidong

    2013-01-01

    In this paper, we present an investigation on the use of Au-Ag alloy popcorn-shaped nanoparticles (NPs) to realise the broadband optical absorption enhancement of dye-sensitized solar cells (DSCs). Both simulation and experimental results indicate that compared with regular plasmonic NPs, such as nano-spheres, irregular popcorn-shaped alloy NPs exhibit absorption enhancement over a broad wavelength range due to the excitation of localized surface plasmons (LSPs) at different wavelengths. The power conversion efficiency (PCE) of DSCs is enhanced by 16% from 5.26% to 6.09% by incorporating 2.38 wt% Au-Ag alloy popcorn NPs. Moreover, by adding a scattering layer on the exterior of the counter electrode, the popcorn NPs demonstrate an even stronger ability to increase the PCE by 32% from 5.94% to 7.85%, which results from the more efficient excitation of the LSP mode on the popcorn NPs. PMID:23817586

  1. Synthesis, characterization, and evaluation of antibacterial effect of Ag nanoparticles against Escherichia coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA)

    PubMed Central

    Paredes, Daissy; Ortiz, Claudia; Torres, Rodrigo

    2014-01-01

    Silver nanoparticles (AgNPs) have been shown great interest because of their potential antibacterial effect. Recently, this has been increased due to resistance in some pathogenic bacteria strains to conventional antibiotics, which has initiated new studies to search for more effective treatments against resistant microorganisms. For these reasons, AgNPs have become an important approach for applications in nanobiotechnology in the development of antibiotic treatment of different bacterial infections. This study was aimed at synthesizing AgNPs using cysteine as a reducer agent and cetyl-tri-methyl-ammonium bromide as a stabilizer in order to obtain more efficient treatment against the pathogen bacteria Escherichia coli O157:H7. These AgNPs were characterized through UV-Vis spectroscopy, transmission electron microscopy, and dynamic light scattering. From these analyses, formation of spherical nanoparticles with an average size of 55 nm was confirmed. Finally, minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) of these AgNPs against pathogenic strains E. coli O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) were determined in both solid and liquid media. MIC and MBC values were around 0.25 μg/mL and 1 μg/mL, respectively. These parameters were comparable to those reported in the literature and were even more effective than other synthesized AgNPs. PMID:24729707

  2. Demonstrating approaches to chemically modify the surface of Ag nanoparticles in order to influence their cytotoxicity and biodistribution after single dose acute intravenous administration.

    PubMed

    Pang, Chengfang; Brunelli, Andrea; Zhu, Conghui; Hristozov, Danail; Liu, Ying; Semenzin, Elena; Wang, Wenwen; Tao, Wuqun; Liang, Jingnan; Marcomini, Antonio; Chen, Chunying; Zhao, Bin

    2016-01-01

    With the advance in material science and the need to diversify market applications, silver nanoparticles (AgNPs) are modified by different surface coatings. However, how these surface modifications influence the effects of AgNPs on human health is still largely unknown. We have evaluated the uptake, toxicity and pharmacokinetics of AgNPs coated with citrate, polyethylene glycol, polyvinyl pyrolidone and branched polyethyleneimine (Citrate AgNPs, PEG AgNPs, PVP AgNPs and BPEI AgNPs, respectively). Our results demonstrated that the toxicity of AgNPs depends on the intracellular localization that was highly dependent on the surface charge. BPEI AgNPs (ζ potential = +46.5 mV) induced the highest cytotoxicity and DNA fragmentation in Hepa1c1c7. In addition, it showed the highest damage to the nucleus of liver cells in the exposed mice, which is associated with a high accumulation in liver tissues. The PEG AgNPs (ζ potential = -16.2 mV) showed the cytotoxicity, a long blood circulation, as well as bioaccumulation in spleen (34.33 µg/g), which suggest better biocompatibility compared to the other chemically modified AgNPs. Moreover, the adsorption ability with bovine serum albumin revealed that the PEG surface of AgNPs has an optimal biological inertia and can effectively resist opsonization or non-specific binding to protein in mice. The overall results indicated that the biodistribution of AgNPs was significantly dependent on surface chemistry: BPEI AgNPs > Citrate AgNPs = PVP AgNPs > PEG AgNPs. This toxicological data could be useful in supporting the development of safe AgNPs for consumer products and drug delivery applications.

  3. Graphene-supported Ag-based core-shell nanoparticles for hydrogen generation in hydrolysis of ammonia borane and methylamine borane.

    PubMed

    Yang, Lan; Luo, Wei; Cheng, Gongzhen

    2013-08-28

    Well-dispersed magnetically recyclable core-shell Ag@M (M = Co, Ni, Fe) nanoparticles (NPs) supported on graphene have been synthesized via a facile in situ one-step procedure, using methylamine borane (MeAB) as a reducing agent under ambient condition. Their catalytic activity toward hydrolysis of ammonia borane (AB) were studied. Although the Ag@Fe/graphene NPs are almost inactive, the as-prepared Ag@Co/graphene NPs are the most reactive catalysts, followed by Ag@Ni/graphene NPs. Compared with AB and NaBH4, the as-synthesized Ag@Co/graphene catalysts which reduced by MeAB exert the highest catalytic activity. Additionally, the Ag@Co NPs supported on graphene exhibit higher catalytic activity than the catalysts with other conventional supports, such as the SiO2, carbon black, and γ-Al2O3. The as-synthesized Ag@Co/graphene NPs exert satisfied catalytic activity, with the turnover frequency (TOF) value of 102.4 (mol H2 min(-1) (mol Ag)(-1)), and the activation energy Ea value of 20.03 kJ/mol. Furthermore, the as-synthesized Ag@Co/graphene NPs show good recyclability and magnetically reusability for the hydrolytic dehydrogenation of AB and MeAB, which make the practical reusing application of the catalysts more convenient. Moreover, this simple synthetic method indicates that MeAB could be used as not only a potential hydrogen storage material but also an efficient reducing agent. It can be easily extended to facile preparation of other graphene supported metal NPs.

  4. Solid-state voltammetry-based electrochemical immunosensor for Escherichia coli using graphene oxide-Ag nanoparticle composites as labels.

    PubMed

    Jiang, Xiaochun; Chen, Kun; Wang, Jing; Shao, Kang; Fu, Tao; Shao, Feng; Lu, Donglian; Liang, Jiangong; Foda, M Frahat; Han, Heyou

    2013-06-21

    A new electrochemical immunosensor based on solid-state voltammetry was fabricated for the detection of Escherichia coli (E. coli) by using graphene oxide-Ag nanoparticle composites (P-GO-Ag) as labels. To construct the platform, Au nanoparticles (AuNPs) were first self-assembled on an Au electrode surface through cysteamine and served as an effective matrix for antibody (Ab) attachment. Under a sandwich-type immunoassay format, the analyte and the probe (P-GO-Ag-Ab) were successively captured onto the immunosensor. Finally, the bonded AgNPs were detected through a solid-state redox process in 0.2 M of KCl solution. Combining the advantages of the high-loading capability of graphene oxide with promoted electron-transfer rate of AuNPs, this immunosensor produced a 26.92-fold signal enhancement compared with the unamplified protocol. Under the optimal conditions, the immunosensor exhibited a wide linear dependence on the logarithm of the concentration of E. coli ranging from 50 to 1.0 × 10(6) cfu mL(-1) with a detection limit of 10 cfu mL(-1). Moreover, as a practical application, the proposed immunosensor was used to monitor E. coli in lake water with satisfactory results.

  5. Laminarin based AgNPs using brown seaweed Turbinaria ornata and its induction of apoptosis in human retinoblastoma Y79 cancer cell lines

    NASA Astrophysics Data System (ADS)

    Remya, R. R.; Radhika Rajasree, S. R.; Suman, T. Y.; Aranganathan, L.; Gayathri, S.; Gobalakrishnan, M.; Karthih, M. G.

    2018-03-01

    Biosynthesis of nanoparticles using isolated compounds from various sources is accepting interest due to their broad array of biological activities and biocompatibility. This paper presents a simple; cost effective and green synthesis of silver nanoparticles (AgNPs) using the polysaccharide, laminarin a storage compound obtained from the brown algae Turbinaria ornata (T. ornata). Initially, the water soluble polysaccharide, laminarin was extracted, purified and analyzed using Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectroscopy (MALDI-TOF MS) and Proton Nuclear Magnetic Resonance (1H NMR). Further, the silver nanoparticles (AgNPs) were synthesized using the isolated laminarin and were characterized by Ultraviolet - visible (UV-vis) spectrophotometer, colour value analysis, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HR-TEM). The free radical scavenging activities were performed and the effect of cytotoxicity against retinoblastoma Y79 cell lines was also evaluated by in vitro studies. Induction of apoptosis was evident by the percentage of cells arrested in G2/M phase using flow cytometry analysis and was further confirmed by DNA fragmentation study which identified the presence of double strand break.

  6. One-step fabrication of recycled Ag nanoparticles/graphene aerogel with high mechanical property for disinfection and catalytic reduction of 4-nitrophonel.

    PubMed

    Zhang, Yi; Yang, Jia-Cheng E; Fu, Ming-Lai; Yuan, Baoling; Gupta, Kiran

    2018-05-15

    Fabrication of smart composites with expected removal property and excellent recycle performance for micro-pollutants including microbes and organic contaminants without formation of second-pollutants is highly desired. In this work, Ag nanoparticles (Ag NPs) homogenously loaded on graphene aerogel (GA) as Ag NPs/GA was facilely fabricated by a one-step process and the composite was characterized in detail. The bactericidal performance of the composite towards escherichia coli (E. coli) was evaluated and the catalytic activity was probed for the reduction of 4-nitrophenol (4-NP). Results showed that the composite contains about 44.4 wt% of well-dispersed Ag NPs with diameters ranging from 10 to 100 nm. Compared with the bare Ag particles or GA, Ag NPs/GA exhibited an enhanced bactericidal performance for 8-lg of E. coli cells with 100% inactivation rate and catalytic activity for 4-NP with 96.6% degradation rate, respectively. Impressively, the 100% inactivation rates for 8-lg of E. coli remained after 7 recycles and the releasing silver was negligible compared with the loaded Ag NPs. Moreover, the used Ag NPs/GA for the catalytic reduction of 4-NP can be regenerated easily by calcination in inert atmosphere. Hence, Ag NPs/GA can be regarded as a promising and cost-efficient composite for environmental remediation.

  7. Bacteriagenic silver nanoparticles: synthesis, mechanism, and applications.

    PubMed

    Singh, Richa; Shedbalkar, Utkarsha U; Wadhwani, Sweety A; Chopade, Balu A

    2015-06-01

    Silver nanoparticles (AgNPs) have received tremendous attention due to their significant antimicrobial properties. Large numbers of reports are available on the physical, chemical, and biological syntheses of colloidal AgNPs. Since there is a great need to develop ecofriendly and sustainable methods, biological systems like bacteria, fungi, and plants are being employed to synthesize these nanoparticles. The present review focuses specifically on bacteria-mediated synthesis of AgNPs, its mechanism, and applications. Bacterial synthesis of extra- and intracellular AgNPs has been reported using biomass, supernatant, cell-free extract, and derived components. The extracellular mode of synthesis is preferred over the intracellular mode owing to easy recovery of nanoparticles. Silver-resistant genes, c-type cytochromes, peptides, cellular enzymes like nitrate reductase, and reducing cofactors play significant roles in AgNP synthesis in bacteria. Organic materials released by bacteria act as natural capping and stabilizing agents for AgNPs, thereby preventing their aggregation and providing stability for a longer time. Regulation over reaction conditions has been suggested to control the morphology, dispersion, and yield of nanoparticles. Bacterial AgNPs have anticancer and antioxidant properties. Moreover, the antimicrobial activity of AgNPs in combination with antibiotics signifies their importance in combating the multidrug-resistant pathogenic microorganisms. Multiple microbicidal mechanisms exhibited by AgNPs, depending upon their size and shape, make them very promising as novel nanoantibiotics.

  8. High-value utilization of lignin to synthesize Ag nanoparticles with detection capacity for Hg²⁺.

    PubMed

    Shen, Zuguang; Luo, Yuqiong; Wang, Qun; Wang, Xiaoying; Sun, Runcang

    2014-09-24

    This study reports the rapid preparation of silver nanoparticles (AgNPs) from Tollens' reagent under microwave irradiation. In the synthesis, lignin with reducing groups and spatial three-dimensional structure was used as reducing and stabilizing agents without other chemical reagents, and the effects of the ratio of lignin to Ag(+), reaction temperature, and heating time on the synthesis of AgNPs were investigated. The obtained AgNPs were further characterized by UV-vis, Malvern particle size, TEM, XRD, and XPS analyses. The structural changes of lignin before and after reaction were also studied by FT-IR, (1)H NMR, (13)C NMR, and GC-MS. The results revealed that the obtained AgNPs were mostly spherical with diameters of around 24 nm. The optimum reaction conditions were a ratio 50 mg of lignin to 0.3 mM of Ag(+), a microwave irradiation temperature of 60 °C, and a heating time of 10 min. Moreover, AgNPs redispersed well in water and ethanol after centrifugation for the removal of lignin. During the formation of AgNPs, lignin was oxidized, and the side chains of lignin were partly disrupted into small molecules, such as hydrocarbon and alcohol. The resultant lignin-AgNPs showed highly selective sensing detection for Hg(2+), and the color of the lignin-AgNP solution containing Hg(2+) decreased gradually with increasing amounts of Hg(2+) within seconds, but the other 19 metal ions had little effect on the color and surface plasmon absorption band of the lignin-AgNPs. Also, there was a linear relationship between the absorbance and Hg(2+) concentration, with a limit of detection concentration of 23 nM. This study provides not only a new way to take advantage of agricultural and forestry residues, but also a green and rapid method for the synthesis of AgNPs to detect the toxic ion Hg(2+) selectively and sensitively.

  9. The effect of nanoparticles size on photocatalytic and antimicrobial properties of Ag-Pt/TiO2 photocatalysts

    NASA Astrophysics Data System (ADS)

    Zielińska-Jurek, Anna; Wei, Zhishun; Wysocka, Izabela; Szweda, Piotr; Kowalska, Ewa

    2015-10-01

    Ag-Pt-modified TiO2 nanocomposites were synthesized using the sol-gel method. Bimetallic modified TiO2 nanoparticles exhibited improved photocatalytic activity under visible-light irradiation, better than monometallic Ag/TiO2 and Pt/TiO2 nanoparticles (NPs). All modified powders showed localized surface plasmon resonance (LSPR) in visible region. The photocatalysts' characteristics by X-ray diffractometry (XRD), scanning transmission electron microscopy (STEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption (BET method for specific surface area) showed that sample with the highest photocatalytic activity had anatase structure, about 93 m2/g specific surface area, maximum plasmon absorption at ca. 420 nm and contained small NPs of silver of 6 nm and very fine platinum NPs of 3 nm. The photocatalytic activity was estimated by measuring the decomposition rate of phenol in 0.2 mM aqueous solution under Vis and UV/vis light irradiation. It was found that size of platinum was decisive for the photocatalytic activity under visible light irradiation, i.e., the smaller Pt NPs were, the higher was photocatalytic activity. While, antimicrobial activities, estimated for bacteria Escherichia coli and Staphylococcus aureus, and pathogenic fungi belonging to Candida family, were only observed for photocatalysts containing silver, i.e., Ag/TiO2 and Ag-Pt/TiO2 nanocomposites.

  10. Synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles and nanowires

    NASA Astrophysics Data System (ADS)

    Xie, Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh

    2010-01-01

    We present the synthesis and visible-light-induced catalytic activity of Ag2S-coupled TiO2 nanoparticles (NPs) and TiO2 nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag2S NPs and TiO2 NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag2S NPs on TiO2 NWs was created. Due to the coupling with such a low bandgap material as Ag2S, the TiO2 nanocomposites could have a visible-light absorption capability much higher than that of pure TiO2. As a result, the synthesized Ag2S/TiO2 nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO2 (Degussa P25, Germany) under visible light.

  11. Bactericidal impact of Ag, ZnO and mixed AgZnO colloidal nanoparticles on H37Rv Mycobacterium tuberculosis phagocytized by THP-1 cell lines.

    PubMed

    Jafari, Alireza; Mosavari, Nader; Movahedzadeh, Farahnaz; Nodooshan, Saeedeh Jafari; Safarkar, Roya; Moro, Rossella; Kamalzadeh, Morteza; Majidpour, Ali; Boustanshenas, Mina; Mosavi, Tahereh

    2017-09-01

    The purpose of this research project was to infection of human macrophages (THP-1) cell lines by H 37 Rv strain of Mycobacterium tuberculosis (H 37 RvMTB) and find out the ratio/dilution of mixture silver (Ag NPs) and zinc oxide nanoparticles (ZnO NPs) whose ability to eliminate phagocytized bacteria compared to rifampicin. The colloidal Ag NPs and ZnO NPs were synthesized and their characteristics were evaluated. The THP-1 cell lines were infected with different concentration of H 37 RvMTB. Next, the infected cells were treated with different ratios/dilutions of Ag NPs, ZnO NPs and rifampicin. The THP-1 were lysed and were cultured in Lowenstein-Jensen agar medium, for eight weeks. The TEM and AFM images of NPs and H 37 RvMTB were supplied. It is observed that Ag NPs, 2 Ag :8 ZnO and 8 Ag :2 ZnO did not have any anti-tubercular effects on phagocytized H 37 RvMTB. Conversely, ZnO NPs somehow eliminated 18.7 × 10 4  CFU ml -1 of H 37 RvMTB in concentration of ∼ 0.468 ppm. To compare with 40 ppm of rifampicin, ∼ 0.663 ppm of 5 Ag :5 ZnO had the ability to kill of H 37 RvMTB, too. Based on previous research, ZnO NPs had strong anti-tubercular impact against H 37 RvMTB to in-vitro condition, but it was toxic in concentration of ∼ 0.468 ppm to both of THP-1 and normal lung (MRC-5) cell lines. It also seems that 5 Ag :5 ZnO is justified because in concentration of ∼ 0.663 ppm of 5 Ag :5 ZnO , phagocytized H 37 RvMTB into the THP-1 had died without any toxicity effects against THP-1 and also MRC-5 cell lines. It is obvious that the mixture of colloidal silver and zinc oxide NPs with ratio of 5 Ag :5 ZnO would be trustworthy options as anti-tubercular nano-drugs in future researches. Copyright © 2017. Published by Elsevier Ltd.

  12. On the Effect of Native SiO2 on Si over the SPR-mediated Photocatalytic Activities of Au and Ag Nanoparticles.

    PubMed

    Wang, Jiale; de Freitas, Isabel C; Alves, Tiago V; Ando, Romulo A; Fang, Zebo; Camargo, Pedro H C

    2017-05-29

    In hybrid materials containing plasmonic nanoparticles such as Au and Ag, charge-transfer processes from and to Au or Ag can affect both activities and selectivity in plasmonic catalysis. Inspired by the widespread utilization of commercial Si wafers in surface-enhanced Raman spectroscopy (SERS) studies, we investigated herein the effect of the native SiO 2 layer on Si wafers over the surface plasmon resonance (SPR)-mediated activities of the Au and Ag nanoparticles (NPs). We prepared SERS-active plasmonic comprised of Au and Ag NPs deposited onto a Si wafer. Here, two kinds of Si wafers were employed: Si with a native oxide surface layer (Si/SiO 2 ) and Si without a native oxide surface layer (Si). This led to Si/SiO 2 /Au, Si/SiO 2 /Ag, Si/Au, and Si/Ag NPs. The SPR-mediated oxidation of p-aminothiophenol (PATP) to p,p'-dimercaptoazobenzene (DMAB) was employed as a model transformation. By comparing the performances and band structures for the Si/Au and Si/Ag relative to Si/SiO 2 /Au and Si/SiO 2 /Ag NPs, it was found that the presence of a SiO 2 layer was crucial to enable higher SPR-mediated PATP to DMAB conversions. The SiO 2 layer acts to prevent the charge transfer of SPR-excited hot electrons from Au or Ag nanoparticles to the Si substrate. This enabled SPR-excited hot electrons to be transferred to adsorbed O 2 molecules, which then participate in the selective oxidation of PATP to DMAB. In the absence of a SiO 2 layer, SPR-excited hot electrons are preferentially transferred to Si instead of adsorbed O 2 molecules, leading to much lower PATP oxidation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Low-dose AgNPs reduce lung mechanical function and innate immune defense in the absence of cellular toxicity.

    PubMed

    Botelho, Danielle J; Leo, Bey Fen; Massa, Christopher B; Sarkar, Srijata; Tetley, Terry D; Chung, Kian Fan; Chen, Shu; Ryan, Mary P; Porter, Alexandra E; Zhang, Junfeng; Schwander, Stephan K; Gow, Andrew J

    2016-01-01

    Multiple studies have examined the direct cellular toxicity of silver nanoparticles (AgNPs). However, the lung is a complex biological system with multiple cell types and a lipid-rich surface fluid; therefore, organ level responses may not depend on direct cellular toxicity. We hypothesized that interaction with the lung lining is a critical determinant of organ level responses. Here, we have examined the effects of low dose intratracheal instillation of AgNPs (0.05 μg/g body weight) 20 and 110 nm diameter in size, and functionalized with citrate or polyvinylpyrrolidone. Both size and functionalization were significant factors in particle aggregation and lipid interaction in vitro. One day post-intratracheal instillation lung function was assessed, and bronchoalveolar lavage (BAL) and lung tissue collected. There were no signs of overt inflammation. There was no change in surfactant protein-B content in the BAL but there was loss of surfactant protein-D with polyvinylpyrrolidone (PVP)-stabilized particles. Mechanical impedance data demonstrated a significant increase in pulmonary elastance as compared to control, greatest with 110 nm PVP-stabilized particles. Seven days post-instillation of PVP-stabilized particles increased BAL cell counts, and reduced lung function was observed. These changes resolved by 21 days. Hence, AgNP-mediated alterations in the lung lining and mechanical function resolve by 21 days. Larger particles and PVP stabilization produce the largest disruptions. These studies demonstrate that low dose AgNPs elicit deficits in both mechanical and innate immune defense function, suggesting that organ level toxicity should be considered.

  14. Enhanced and Facet-specific Electrocatalytic Properties of Ag/Bi2Fe4O9 Composite Nanoparticles.

    PubMed

    Wang, Kai; Xu, Xiaoguang; Lu, Liying; Wang, Haicheng; Li, Yan; Wu, Yong; Miao, Jun; Zhang, Jin Zhong; Jiang, Yong

    2018-04-18

    Ag/Bi 2 Fe 4 O 9 nanoparticles (BFO NPs) have been synthesized using a two-step approach involving glycine combustion and visible light irradiation. Their structures were characterized in detail using X-ray diffraction, transmission electron microscope, scanning electron microscopy, and scanning transmission electron microscopy techniques. Their electrocatalytic properties were studied through enzymatic glucose detection with an amperometric biosensor. The Ag deposited on selective crystal facets of BFO NPs significantly enhanced their electrocatalytic activity. To gain insights into the origin of the enhanced electrocatalytic activities, we have carried out studies of Ag + reduction and Mn 2+ oxidation reaction at the {200} and {001} facets, respectively. The results suggest effective charge separation on the BFO NP surfaces, which is likely responsible for the enhanced electrocatalytic properties. Furthermore, enhanced ferromagnetism was observed after the Ag deposition on BFO NPs, which may be related to the improved electrocatalytic properties through spin-dependent charge transport. The facet-specific electrocatalytic properties are highly interesting and desired for chemical reactions. This study demonstrates that Ag/BFO NPs are potentially useful for electrocatalytic applications including biosensing and chemical synthesis with high product selectivity.

  15. Fabrication of uniformly dispersed Ag nanoparticles loaded TiO{sub 2} nanotube arrays for enhancing photoelectrochemical and photocatalytic performances under visible light irradiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yi, Junhui; Zhang, Shengsen; Wang, Hongjuan

    2014-12-15

    Graphical abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method, which exhibited the enhanced photoelectrochemical and photocatalytic performances under visible-light irradiation due to the more effective separation of photo-generated electron–hole pairs and faster interfacial charge transfer. - Highlights: • Highly dispersed Ag nanoparticles (NPs) are successfully prepared by polyol method. • Ag NPs are uniformly loaded on the surface of the TiO{sub 2} nanotube arrays (NTs). • Ag/TiO{sub 2}-NTs exhibit the enhanced photocatalytic activity under visible-light. • The enhanced photocurrent ismore » explained by electrochemical impedance spectroscopy. - Abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method. The as-prepared Ag/TiO{sub 2}-NTs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV–vis diffusion reflectance spectroscopy. Photoelectrochemical behaviors were investigated via photocurrent response and electrochemical impedance spectroscopy (EIS). Photocatalytic activity of Ag/TiO{sub 2}-NTs was evaluated by degradation of acid orange II under visible light irradiation. The results showed that photocatalytic efficiency of Ag/TiO{sub 2}-NTs is more than 5 times higher than that of pure TiO{sub 2} NTs. Comparing with the electrochemical deposition method, the photocatalytic activity of Ag/TiO{sub 2}-NTs prepared by polyol method has been obviously increased.« less

  16. Ag Nanoparticles (Ag NM300K) in the Terrestrial Environment: Effects at Population and Cellular Level in Folsomia candida (Collembola)

    PubMed Central

    Mendes, Luís André; Maria, Vera L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The effects of nanomaterials have been primarily assessed based on standard ecotoxicity guidelines. However, by adapting alternative measures the information gained could be enhanced considerably, e.g., studies should focus on more mechanistic approaches. Here, the environmental risk posed by the presence of silver nanoparticles (Ag NM300K) in soil was investigated, anchoring population and cellular level effects, i.e., survival, reproduction (28 days) and oxidative stress markers (0, 2, 4, 6, 10 days). The standard species Folsomia candida was used. Measured markers included catalase (CAT), glutathione reductase (GR), glutathione S-transferase (GST), total glutathione (TG), metallothionein (MT) and lipid peroxidation (LPO). Results showed that AgNO3 was more toxic than AgNPs at the population level: reproduction EC20 and EC50 was ca. 2 and 4 times lower, respectively. At the cellular level Correspondence Analysis showed a clear separation between AgNO3 and AgNP throughout time. Results showed differences in the mechanisms, indicating a combined effect of released Ag+ (MT and GST) and of AgNPs (CAT, GR, TG, LPO). Hence, clear advantages from mechanistic approaches are shown, but also that time is of importance when measuring such responses. PMID:26473892

  17. A New Smart Surface-Enhanced Raman Scattering Sensor Based on pH-Responsive Polyacryloyl Hydrazine Capped Ag Nanoparticles.

    PubMed

    Yuan, Shuai; Ge, Fengyan; Zhou, Man; Cai, Zaisheng; Guang, Shanyi

    2017-08-14

    A novel pH-responsive Ag@polyacryloyl hydrazide (Ag@PAH) nanoparticle for the first time as a surface-enhanced Raman scattering (SERS) substrate was prepared without reducing agent and end-capping reagent. Ag@PAH nanoparticles exhibited an excellent tunable detecting performance in the range from pH = 4 to pH = 9. This is explained that the swelling-shrinking behavior of responsive PAH can control the distance between Ag NPs and the target molecules under external pH stimuli, resulting in the tunable LSPR and further controlled SERS. Furthermore, Ag@PAH nanoparticles possessed an ultra-sensitive detecting ability and the detection limit of Rhodamine 6G reduced to 10 -12  M. These advantages qualified Ag@PAH NP as a promising smart SERS substrate in the field of trace analysis and sensors.

  18. A New Smart Surface-Enhanced Raman Scattering Sensor Based on pH-Responsive Polyacryloyl Hydrazine Capped Ag Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yuan, Shuai; Ge, Fengyan; Zhou, Man; Cai, Zaisheng; Guang, Shanyi

    2017-08-01

    A novel pH-responsive Ag@polyacryloyl hydrazide (Ag@PAH) nanoparticle for the first time as a surface-enhanced Raman scattering (SERS) substrate was prepared without reducing agent and end-capping reagent. Ag@PAH nanoparticles exhibited an excellent tunable detecting performance in the range from pH = 4 to pH = 9. This is explained that the swelling-shrinking behavior of responsive PAH can control the distance between Ag NPs and the target molecules under external pH stimuli, resulting in the tunable LSPR and further controlled SERS. Furthermore, Ag@PAH nanoparticles possessed an ultra-sensitive detecting ability and the detection limit of Rhodamine 6G reduced to 10-12 M. These advantages qualified Ag@PAH NP as a promising smart SERS substrate in the field of trace analysis and sensors.

  19. Preparation of an agar-silver nanoparticles (A-AgNp) film for increasing the shelf-life of fruits.

    PubMed

    Gudadhe, Janhavi A; Yadav, Alka; Gade, Aniket; Marcato, Priscyla D; Durán, Nelson; Rai, Mahendra

    2014-12-01

    Preparation of protective coating possessing antimicrobial properties is present day need as they increase the shelf life of fruits and vegetables. In the present study, preparation of agar-silver nanoparticle film for increasing the shelf life of fruits is reported. Silver nanoparticles (Ag-NPs) biosynthesised using an extract of Ocimum sanctum leaves, were mixed with agar-agar to prepare an agar-silver nanoparticles (A-AgNp) film. This film was surface-coated over the fruits, Citrus aurantifolium (Thornless lime) and Pyrus malus (Apple), and evaluated for the determination of antimicrobial activity of A-AgNp films using disc diffusion method, weight loss and shelf life of fruits. This study demonstrates that these A-AgNp films possess antimicrobial activity and also increase the shelf life of fruits.

  20. Fungicidal activity of silver nanoparticles against Alternaria brassicicola

    NASA Astrophysics Data System (ADS)

    Gupta, Deepika; Chauhan, Pratima

    2016-04-01

    This work highlighted the fungicidal properties of silver nanoparticles against Alternaria brassicicola. Alternaria brassicicola causes Black spot of Cauliflower, radish, cabbage, kale which results in sever agricultural loss. We treat the synthesised silver nanoparticles (AgNPs) of 10, 25, 50, 100 and 110 ppm concentrations against Alternaria brassicicola on PDA containing Petri dish. We calculated inhibitory rate (%) in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. Treatment with 100ppm AgNPs resulted in maximum inhibition of Alternaria brassicicola i.e.92.2%. 110ppm of AgNPS also shows the same result, therefore 100ppm AgNPs was treated as optimize concentration. AgNPs effectively inhibited the growth of a Alternaria brassicicola, which suggests that AgNPs could be used as fungicide in plant disease management. Further research and development are necessary to translate this technology into plant disease management strategies.

  1. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles. Part 1. Aggregation and dissolution.

    PubMed

    Unrine, Jason M; Colman, Benjamin P; Bone, Audrey J; Gondikas, Andreas P; Matson, Cole W

    2012-07-03

    To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet-visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22-28% of the particulate Ag was associated with thiols and 5-14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.

  2. Biosynthesis of Gold and Silver Nanoparticles Using Extracts of Callus Cultures of Pumpkin (Cucurbita maxima).

    PubMed

    Iyer, R Indira; Panda, Tapobrata

    2018-08-01

    The potential of callus cultures and field-grown organs of pumpkin (Cucurbita maxima) for the biosynthesis of nanoparticles of the noble metals gold and silver has been investigated. Biosynthesis of AuNPs (gold nanoparticles) and AgNPs (silver nanoparticles) was obtained with flowers of C. maxima but not with pulp and seeds. With callus cultures established in MS-based medium the biogenesis of both AuNPs and AgNPs could be obtained. At 65 °C the biogenesis of AuNPs and AgNPs by callus extracts was enhanced. The AuNPs and AgNPs have been characterized by UV-visible spectroscopy, TEM, DLS and XRD. Well-dispersed nanoparticles, which exhibited a remarkable diversity in size and shape, could be visualized by TEM. Gold nanoparticles were found to be of various shapes, viz., rods, triangles, star-shaped particles, spheres, hexagons, bipyramids, discoid particles, nanotrapezoids, prisms, cuboids. Silver nanoparticles were also of diverse shapes, viz., discoid, spherical, elliptical, triangle-like, belt-like, rod-shaped forms and cuboids. EDX analysis indicated that the AuNPs and AgNPs had a high degree of purity. The surface charges of the generated AuNPs and AgNPs were highly negative as indicated by zeta potential measurements. The AuNPs and AgNPs exhibited remarkable stability in solution for more than four months. FTIR studies indicated that biomolecules in the callus extracts were associated with the biosynthesis and stabilisation of the nanoparticles. The synthesized AgNPs could catalyse degradation of methylene blue and exhibited anti-bacterial activity against E. coli DH5α. There is no earlier report of the biosynthesis of nanoparticles by this plant species. Callus cultures of Cucurbita maxima are effective alternative resources of biomass for synthesis of nanoparticles.

  3. Antibacterial activity of nitric oxide releasing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Seabra, Amedea B.; Manosalva, Nixson; de Araujo Lima, Bruna; Pelegrino, Milena T.; Brocchi, Marcelo; Rubilar, Olga; Duran, Nelson

    2017-06-01

    Silver nanoparticles (AgNPs) are well known potent antimicrobial agents. Similarly, the free radical nitric oxide (NO) has important antibacterial activity, and due to its instability, the combination of NO and nanomaterials has been applied in several biomedical applications. The aim of this work was to synthesize, characterize and evaluate the antibacterial activity of a new NO-releasing AgNPs. Herein, AgNPs were synthesized by the reduction of silver ions (Ag+) by catechin, a natural polyphenol and potent antioxidant agent, derived from green tea extract. Catechin acts as a reducing agent and as a capping molecule on the surface of AgNPs, minimizing particle agglomeration. The as-synthesized nanoparticles were characterized by different techniques. The results showed the formation of AgNPs with average hydrodynamic size of 44 nm, polydispersity index of 0.21, and zeta potential of -35.9 mV. X-ray diffraction and Fourier transform infrared spectroscopy revealed the presence of the AgNP core and cathecin as capping agent. The low molecular weight mercaptosuccinic acid (MSA), which contain free thiol group, was added on the surface of catechin-AgNPs, leading to the formation of MSA-catechin-AgNPs (the NO precursor nanoparticle). Free thiol groups of MSA-catechin-AgNPs were nitrosated leading to the formation of S-nitroso-mercaptosuccinic acid (S-nitroso-MSA), the NO donor. The amount of 342 ± 16 µmol of NO was released per gram of S-nitroso-MSA-catechin-AgNPs. The antibacterial activities of catechin-AgNPs, MSA-catechin-AgNPs, and S-nitroso-MSA-catechin-AgNPs were evaluated towards different resistant bacterial strains. The results demonstrated an enhanced antibacterial activity of the NO-releasing AgNP. For instance, the minimal inhibitory concentration values for Pseudomonas aeruginosa (ATCC 27853) incubated with AgNPs-catechin, AgNPs-catechin-MSA, and AgNPs-catechin-S-nitroso-MSA were found to be 62, 125 and 3 µg/mL, respectively. While in the case of

  4. γ-Irradiation assisted synthesis of graphene oxide sheets supported Ag nanoparticles with single crystalline structure and parabolic distribution from interlamellar limitation

    NASA Astrophysics Data System (ADS)

    Yue, Yunhao; Zhou, Baoming; Shi, Jie; Chen, Cheng; Li, Nan; Xu, Zhiwei; Liu, Liangsen; Kuang, Liyun; Ma, Meijun; Fu, Hongjun

    2017-05-01

    This paper reported a method to fabricate graphene oxide sheets supported Ag nanoparticles (AgNPs/GOS) with single crystalline structure and parabolic distribution without surfactant or functional agent. We used imidazole silver nitrate as intercalation precursor into the layers of graphite oxide, and subsequently reduction and growth of interlamellar AgNPs were induced via γ-irradiation. The results illustrated that the synergism of interlamellar limitation of graphite oxide and fragmentation ability of γ-irradiation could prevent coalescent reaction of AgNPs with other oligomeric clusters, and the single crystalline and small-sized (below 13.9 nm) AgNPs were prepared. Moreover, the content and size of AgNPs exhibited parabolic distribution on GOS surface because the graphite oxide exfoliated to GOS from the edge to the central area of layers. In addition, complete exfoliation degree of GOS and large-sized AgNPs were obtained simultaneously under suitable silver ions concentration. Optimized composites exhibited outstanding surface-enhanced Raman scattering properties for crystal violet with enhancement factor of 1.3 × 106 and detection limit of 1.0 × 10-7 M, indicating that the AgNPs/GOS composites could be applied to trace detection of organic dyes molecules. Therefore, this study presented a strategy for developing GOS supported nanometal with single crystalline structure and parabolic distribution based on γ-irradiation.

  5. Novel method for synthesis of silver nanoparticles and their application on wool

    NASA Astrophysics Data System (ADS)

    Boroumand, Majid Nasiri; Montazer, Majid; Simon, Frank; Liesiene, Jolanta; Šaponjic, Zoran; Dutschk, Victoria

    2015-08-01

    In this study, a new method for the synthesis of silver nanoparticles (AgNPs) suitable to impart antibacterial properties of wool fabric is proposed. AgNPs were synthesized by a biochemical reduction method. An aqueous solution of extracted dye from Pomegranate peel was used as a reducing agent for the synthesis of AgNPs from silver nitrate. The ratio of dye to silver nitrate concentration (RDye/Ag = [Dye]/[AgNO3]) is the influencing factor in the synthesis of silver nanoparticles. The nanoparticles formation was followed by UV/Vis absorption spectroscopy. The size and shape of AgNPs were studied by transmission electron microscopy (TEM). The size distribution and Zetapotential of nanoparticles were evaluated using diffraction light scattering (DLS) measurements. The antibacterial potential of biosynthesized silver nanoparticles against Escherichia coli (E. coli) was examined qualitatively and quantitatively. Kinetic analysis of the bacteria reduction using AgNPs synthesized in different way was performed. AgNPs were applied on wool fabrics by exhaustion. The changes in surface morphology of wool fibers after AgNPs loading were studied using scanning electron microscopy (SEM). The amounts of silver deposited on wool fabrics at different pH and temperature were compared applying energy-dispersive X-ray spectroscopy (EDX). AgNPs loaded fabrics showed excellent antibacterial efficiency even after five washing cycles. To investigate the nature of interaction and bonding between the AgNPs and the wool substrate XPS measurements were performed.

  6. Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles.

    PubMed

    Dzimitrowicz, Anna; Jamroz, Piotr; Nyk, Marcin; Pohl, Pawel

    2016-04-06

    A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO₃ solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system.

  7. Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles

    PubMed Central

    Dzimitrowicz, Anna; Jamroz, Piotr; Nyk, Marcin; Pohl, Pawel

    2016-01-01

    A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO3 solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system. PMID:28773393

  8. Graphene Oxide/Ag Nanoparticles Cooperated with Simvastatin as a High Sensitive X-Ray Computed Tomography Imaging Agent for Diagnosis of Renal Dysfunctions.

    PubMed

    Li, Zhan; Tian, Longlong; Liu, Jianli; Qi, Wei; Wu, Qiang; Wang, Haijing; Ali, Mohammad Chand; Wu, Wangsuo; Qiu, Hongdeng

    2017-09-01

    Graphene oxides (GO) are attracting much attention in the diagnosis and therapy of the subcutaneous tumor as a novel biomaterial, but its diagnosis to tissue dysfunction is yet to be found. Here, a novel application of GO for diagnosis of renal dysfunction via contrast-enhanced computed tomography (CT) is proposed. In order to serve as contrast-enhanced agent, Ag nanoparticles (AgNPs) are composited on the surface of GO to promote its X-ray absorption, and then simvastatin is coinjected for eliminating in vivo toxicity induced by AgNPs. It is found that GO/AgNPs can enhance the imaging of CT into the lung, liver, and kidney of mice for a long circulation time (≈24 h) and a safety profile in vivo in the presence of simvastatin. Interestingly, the lower dose of GO/AgNPs (≈0.5 mg per kg bw) shows an excellent performance for CT imaging of renal perfusion, and visually exhibits the right renal dysfunction in model mice. Hence, this work suggests that graphene nanoparticles will play a vital role for the future medical translational development including drug carrier, biosensing, and disease therapy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Highly sensitive colorimetric detection of glucose in a serum based on DNA-embeded Au@Ag core-shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Kang, Fei; Hou, Xiangshu; Xu, Kun

    2015-10-01

    Glucose is a key energy substance in diverse biology and closely related to the life activities of the organism. To develop a simple and sensitive method for glucose detection is extremely urgent but still remains a key challenge. Herein, we report a colorimetric glucose sensor in a homogeneous system based on DNA-embedded core-shell Au@Ag nanoparticles. In this assay, a glucose substrate was first catalytically oxidized by glucose oxidase to produce H2O2 which would further oxidize and gradually etch the outer silver shell of Au@Ag nanoparticles. Afterwards, the solution color changed from yellow to red and the surface plasmon resonance (SPR) band of Au@Ag nanoparticles declined and red-shifted from 430 to 516 nm. Compared with previous silver-based glucose colorimetric detection strategies, the distinctive SPR band change is superior to the color variation, which is critical to the high sensitivity of this assay. Benefiting from the outstanding optical property, robust stability and well-dispersion of the core-shell Au@AgNPs hybrid, this colorimetric assay obtained a detection limit of glucose as low as 10 nM, which is at least a 10-fold improvement over other AgNPs-based procedures. Moreover, this optical biosensor was successfully employed to the determination of glucose in fetal bovine serum.

  10. No evidence of the genotoxic potential of gold, silver, zinc oxide and titanium dioxide nanoparticles in the SOS chromotest.

    PubMed

    Nam, Sun-Hwa; Kim, Shin Woong; An, Youn-Joo

    2013-10-01

    Gold nanoparticles (Au NPs), silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs) and titanium dioxide nanoparticles (TiO2 NPs) are widely used in cosmetic products such as preservatives, colorants and sunscreens. This study investigated the genotoxicity of Au NPs, Ag NPs, ZnO NPs and TiO2 NPs using the SOS chromotest with Escherichia coli PQ37. The maximum exposure concentrations for each nanoparticle were 3.23 mg l(-1) for Au NPs, 32.3 mg l(-1) for Ag NPs and 100 mg l(-1) for ZnO NPs and TiO2 NPs. Additionally, in order to compare the genotoxicity of nanoparticles and corresponding dissolved ions, the ions were assessed in the same way as nanoparticles. The genotoxicity of the titanium ion was not assessed because of the extremely low solubility of TiO2 NPs. Au NPs, Ag NPs, ZnO NPs, TiO2 NPs and ions of Au, Ag and Zn, in a range of tested concentrations, exerted no effects in the SOS chromotest, evidenced by maximum IF (IFmax) values of below 1.5 for all chemicals. Owing to the results, nanosized Au NPs, Ag NPs, ZnO NPs, TiO2 NPs and ions of Au, Ag and Zn are classified as non-genotoxic on the basis of the SOS chromotest used in this study. To the best of our knowledge, this is the first study to evaluate the genotoxicity of Au NPs, Ag NPs, ZnO NPs and TiO2 NPs using the SOS chromotest. Copyright © 2012 John Wiley & Sons, Ltd.

  11. Invoking Direct Exciton-Plasmon Interactions by Catalytic Ag Deposition on Au Nanoparticles: Photoelectrochemical Bioanalysis with High Efficiency.

    PubMed

    Ma, Zheng-Yuan; Xu, Fei; Qin, Yu; Zhao, Wei-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-04-19

    In this work, direct exciton-plasmon interactions (EPI) between CdS quantum dots (QDs) and Ag nanoparticles (NPs) were invoked ingeniously by catalytic Ag deposition on Au NPs for the stimulation of high efficient damping effect toward the excitonic responses in CdS QDs, on the basis of which a novel photoelectrochemical (PEC) bioanalytical format was achieved for sensitive microRNA detection. Specifically, upon the configurational change from the hairpin probe DNA to the "Y"-shaped ternary conjugate consisting of the original probe DNA, assistant DNA, and the target microRNA, the alkaline phosphatase (ALP) catalytic chemistry would then trigger the transition of the interparticle interplay from the CdS QDs-Au NPs to the CdS QDs-Ag NPs systems for the microRNA detection due to the dependence of the photocurrent quenching on the target concentration. This work not only provided a unique method for EPI generation among the PEC nanosystems but also offered a versatile and general protocol for future PEC bioanalysis development.

  12. Substrates coated with silver nanoparticles as a neuronal regenerative material

    PubMed Central

    Alon, Noa; Miroshnikov, Yana; Perkas, Nina; Nissan, Ifat; Gedanken, Aharon; Shefi, Orit

    2014-01-01

    Much effort has been devoted to the design of effective biomaterials for nerve regeneration. Here, we report the novel use of silver nanoparticles (AgNPs) as regenerative agents to promote neuronal growth. We grew neuroblastoma cells on surfaces coated with AgNPs and studied the effect on the development of the neurites during the initiation and the elongation growth phases. We find that the AgNPs function as favorable anchoring sites, and the growth on the AgNP-coated substrates leads to a significantly enhanced neurite outgrowth. Cells grown on substrates coated with AgNPs have initiated three times more neurites than cells grown on uncoated substrates, and two times more than cells grown on substrates sputtered with a plain homogenous layer of silver. The growth of neurites on AgNPs in the elongation phase was enhanced as well. A comparison with substrates coated with gold nanoparticles (AuNPs) and zinc oxide nanoparticles (ZnONPs) demonstrated a clear silver material-driven promoting effect, in addition to the nanotopography. The growth on substrates coated with AgNPs has led to a significantly higher number of initiating neurites when compared to substrates coated with AuNPs or ZnONPs. All nanoparticle-coated substrates affected and promoted the elongation of neurites, with a significant positive maximal effect for the AgNPs. Our results, combined with the well-known antibacterial effect of AgNPs, suggest the use of AgNPs as an attractive nanomaterial – with dual activity – for neuronal repair studies. PMID:24872701

  13. Spherical LDH-Ag°-montmorillonite heterocoagulated system with a pH-dependent sol-gel structure for controlled accessibility of AgNPs immobilized on the clay lamellae.

    PubMed

    Deák, Ágota; Janovák, László; Tallósy, Szabolcs Péter; Bitó, Tamás; Sebők, Dániel; Buzás, Norbert; Pálinkó, István; Dékány, Imre

    2015-02-17

    Aqueous suspensions of spherical ZnMgAl-layered double hydroxides [LDH(sph)] and antibacterial silver nanoparticles (AgNPs) deposited on the lamellae of montmorillonite were used for the synthesis of composites, which behave like coherent gels at low pH (≲4.5) and incoherent sols at higher pH (≳4.5). The composition of the composite was chosen as LDH(sph)/Ag°-montm. = 25:75 wt % in order to ensure a sol-gel transition that can also be characterized by viscometry. This pH-sensitive heterocoagulated system consisting of oppositely charged colloid particles was suitable for the release of antimicrobial AgNPs immobilized on the clay lamellae via a pH-controlled gel-sol transition. The heterocoagulation process was also characterized by surface charge titration measurements. Spherical LDH/Ag°-montmorillonite composite samples were identified by X-ray diffraction (XRD) measurements. The morphological properties of the composites were studied, and the presence of the heterocoagulated structure was confirmed by scanning electron microscopy (SEM). The nanoscale structure of the LDH(sph)-Ag°-montmorillonite composite obtained was also verified by small-angle X-ray scattering (SAXS), and the rheological characteristics were studied at various pH values. The viscosity and yield value of the composite decreased by an order of magnitude upon increasing the pH from 3.0 to 5.5. The sol-gel transition of the composite suspension was reversible in the previously mentioned pH range.

  14. The Green Synthesis and Evaluation of Silver Nanoparticles and Zinc Oxide Nanoparticles

    NASA Astrophysics Data System (ADS)

    Gebear-Eigzabher, Bellsabel

    Nanoparticle (NP) research has received exceptional attention as the field of study that contributes to transforming the world of materials science. When implementing NPs in consumer and industrial products, their unique properties improve technologies to the extent of significant game-changing breakthroughs. Conversely, the increased production of NPs, their use, their disposal or inadvertent release in the environment drove the need for processes and policies that ensures consumer and environmental safety. Mitigation of any harmful effects that NPs could potentially have combines methods of safe preparation, safe handling and safe disposal as well as containment of any inadvertent release. Our focus is in safe preparation of nanomaterials and we report green and energy efficient synthesis methods for metal NPs and metal oxide NPs of two popular materials: silver (Ag) and zinc oxide (ZnO). The thesis explained: 1) The impact of NPs in nowadays' world; 2) Synthesis methods that were designed to include environmentally-friendly staring materials and energy-saving fabrication processes, with emphasis on maintaining NPs final size and morphology when compared with existing methods; and 3) Nanoparticles characterization and data collection which allowed us to determine and/or validate their properties. Nanoparticles were studied using transmission electron microscope (TEM), X-Ray powder diffraction (XRD), low-voltage (5 keV) transmission electron microscopy (LV EM 5), Fourier-Transform Infrared Spectroscopy (FT-IR), and Ultraviolet-Visible (UV-Vis) spectroscopy. We developed an aqueous-based preparation of zinc oxide nanoparticles (ZnO NPs) using microwave-assisted chemistry to render a well-controlled particle size distribution within each set of reaction conditions in the range of 15 nm to 75 nm. We developed a scalable silver nanoparticles synthesis by chemical reduction methods. The NPs could be used in consumer products. The measurement tools for consumer products

  15. Bioactive compound synthesis of Ag nanoparticles from leaves of Melia azedarach and its control for mosquito larvae.

    PubMed

    Ramanibai, R; Velayutham, K

    2015-02-01

    Larvicidal activity of synthesized Ag nanoparticles using 2,7.bis[2-[diethylamino]-ethoxy]fluorence isolate from the Melia azedarach leaves against Aedes aegypti and Culex quinquefasciatus. Six fractions were collected and concentrated, fraction three showed a single spot on TLC which was found to be a pure compound. The structures were elucidated by analyses of UV, MS, and NMR spectral data. The maximum mortality was fluorence against A. aegypti and C. quinquefasciatus (LC50 = 7.94, LC90 = 23.82 ppm and LC50 = 13.58 and LC90 = 40.03 ppm). The synthesized nanoparticles were characterized and confirmed as Ag nanoparticles by using UV-visible spectroscopy, XRD and HRTEM analysis. The maximum activity was observed in synthesized AgNPs against A. aegypti and C. quinquefasciatus (LC50 = 4.27 and 3.43 µg/mL; LC90 = 12.61 and 10.29 µg/mL). Rephrase test was studied to analyze the toxicological effects of Mesocyclops pehpeiensis for 24 h at synthesized AgNPs. This method is considered as an innovative alternative approach that can be used to control mosquitoes. Copyright © 2014. Published by Elsevier Ltd.

  16. Green Nanoparticles for Mosquito Control

    PubMed Central

    Soni, Namita; Prakash, Soam

    2014-01-01

    Here, we have used the green method for synthesis of silver and gold nanoparticles. In the present study the silver (Ag) and gold (Au) nanoparticles (NPs) were synthesized by using the aqueous bark extract of Indian spice dalchini (Cinnamomum zeylanicum) (C. zyelanicum or C. verum J. Presl). Additionally, we have used these synthesized nanoparticles for mosquito control. The larvicidal activity has been tested against the malaria vector Anopheles stephensi and filariasis vector Culex quinquefasciatus. The results were obtained using UV-visible spectrophotometer and the images were recorded with a transmission electron microscope (TEM). The efficacy tests were then performed at different concentrations and varying numbers of hours by probit analysis. The synthesized AgNPs were in spherical shape and average sizes (11.77 nm AgNPs and 46.48 nm AuNPs). The larvae of An. stephensi were found highly susceptible to the synthesized AgNPs and AuNPs than the Cx. quinquefasciatus. These results suggest that the C. zeylanicum synthesized silver and gold nanoparticles have the potential to be used as an ideal ecofriendly approach for the control of mosquito. PMID:25243210

  17. Biopolymer mediated nanoparticles synthesized from Adenia hondala for enhanced tamoxifen drug delivery in breast cancer cell line

    NASA Astrophysics Data System (ADS)

    Varadharajaperumal, Pradeepa; Subramanian, Balakumar; Santhanam, Amutha

    2017-09-01

    Silver nanoparticles (AgNPs) are an important class of nanomaterials, which have used as antimicrobial and disinfectant agents due to their detrimental effect on target cells. In the present study it was explored to deliver a novel tamoxifen drug system that can be used in breast cancer treatment, based on chitosan coated silver nanoparticles on MCF-7 human breast cancer cells. AgNPs synthesized from Adenia hondala tuber extract were used to make the chitosan coated AgNPs (Ch-AgNPs), in which the drug tamoxifen was loaded on chitosan coated silver nanoparticles (Tam-Ch-AgNPs) to construct drug loaded nanoparticles as drug delivery system. The morphology and characteristics of the Ch-AgNPs were investigated by UV, FTIR, zeta potential and FESEM. Furthermore, the toxicity of AgNPs, Ch-AgNPs, Tam-Ch-AgNPs was evaluated through cell viability, lactate dehydrogenase leakage, reactive oxygen species generation, caspase-3, DNA laddering, and TUNEL assay in human breast cancer cells (MCF-7) and HBL-100 continuous cell line as a control. Treatment of cancer cells with various concentrations of AgNPs, Ch-AgNPs, Tam-Ch-AgNPs for 24 h revealed that Tam-Ch-AgNPs could inhibit cell viability and induce significant membrane leakage in a dose-dependent manner. Cells exposed to Tam-Ch-AgNPs showed increased reactive oxygen species and hydroxyl radical production when compared to AgNPs, Ch-AgNPs. Furthermore, the apoptotic effects of AgNPs, Ch-AgNPs, Tam-Ch-AgNPs were confirmed by activation of caspase-3 and DNA nuclear fragmentation. The present findings suggest that Tam-Ch-AgNPs could contribute to the development of a suitable anticancer drug delivery.

  18. Ag nanoparticle-filled TiO2 nanotube arrays prepared by anodization and electrophoretic deposition for dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wei, Xing; Sugri Nbelayim, Pascal; Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

    2017-03-01

    A layer of TiO2 nanotube (TNT) arrays with a thickness of 13 μm is synthesized by a two-step anodic oxidation from Ti metal foil. Surface charged Ag nanoparticles (NPs) are prepared by chemical reduction. After a pretreatment of the TNT arrays by acetone vapor, Ag NP filled TNT arrays can be achieved by electrophoretic deposition (EPD). Effects of the applied voltage during EPD such as DC-AC difference, frequency and waveform are investigated by quantitative analysis using atomic absorption spectroscopy. The results show that the best EPD condition is using DC 2 V + AC 4 V and a square wave of 1 Hz as the applied voltage. Back illuminated dye-sensitized solar cells are fabricated from TNT arrays with and without Ag NPs. The efficiency increased from 3.70% to 5.01% by the deposition of Ag NPs.

  19. Preparation and characterization of biocompatible silver nanoparticles using pomegranate peel extract.

    PubMed

    Nasiriboroumand, Majid; Montazer, Majid; Barani, Hossein

    2018-02-01

    The potential application of any nanoparticles, including silver nanoparticles (AgNPs), strongly depends on their stability against aggregation. In the current study, an aqueous extract of pomegranate peel was used as a stabilizer during synthesis of AgNPs. Nanoparticles have been prepared by the chemical reduction method from an aqueous solution of silver nitrate in the presence of sodium borohydride as a reducing agent. The AgNPs were characterized by dynamic light scattering (DLS), zeta-potential measurements, UV-Vis spectroscopy and transmission electron microscopy (TEM). The antibacterial efficiency of AgNPs against Escherichia coli was investigated. The size, polydispersity index, FWHM, and colloidal stability of nanoparticles in dispersion depends on the extract concentrations. In the presence of pomegranate peel extract, the nanoparticles suspension shows colloidal stability at least for a week. Our studies show that synthesized AgNPs with the above described procedure were stable at pH = 3-12 and in the temperature range of 25-85 °C. Additionally, AgNPs exhibit antibacterial properties, especially at the lowest amount of extract to silver ratio (K Extract/Ag ). Copyright © 2018. Published by Elsevier B.V.

  20. Multi-Shaped Ag Nanoparticles in the Plasmonic Layer of Dye-Sensitized Solar Cells for Increased Power Conversion Efficiency.

    PubMed

    Song, Da Hyun; Kim, Ho-Sub; Suh, Jung Sang; Jun, Bong-Hyun; Rho, Won-Yeop

    2017-06-04

    The use of dye-sensitized solar cells (DSSCs) is widespread owing to their high power conversion efficiency (PCE) and low cost of manufacturing. We prepared multi-shaped Ag nanoparticles (NPs) and introduced them into DSSCs to further enhance their PCE. The maximum absorption wavelength of the multi-shaped Ag NPs is 420 nm, including the shoulder with a full width at half maximum (FWHM) of 121 nm. This is a broad absorption wavelength compared to spherical Ag NPs, which have a maximum absorption wavelength of 400 nm without the shoulder of 61 nm FWHM. Therefore, when multi-shaped Ag NPs with a broader plasmon-enhanced absorption were coated on a mesoporous TiO₂ layer on a layer-by-layer structure in DSSCs, the PCE increased from 8.44% to 10.22%, equivalent to an improvement of 21.09% compared to DSSCs without a plasmonic layer. To confirm the plasmon-enhanced effect on the composite film structure in DSSCs, the PCE of DSSCs based on the composite film structure with multi-shaped Ag NPs increased from 8.58% to 10.34%, equivalent to an improvement of 20.51% compared to DSSCs without a plasmonic layer. This concept can be applied to perovskite solar cells, hybrid solar cells, and other solar cells devices.

  1. Studies of antibacterial efficacy of different biopolymer protected silver nanoparticles synthesized under reflux condition

    NASA Astrophysics Data System (ADS)

    Su, Chia Hung; Velusamy, Palaniyandi; Kumar, Govindarajan Venkat; Adhikary, Shritama; Pandian, Kannaiyan; Anbu, Periyasamy

    2017-01-01

    In the present study, a simple method to impregnate silver nanoparticles (AgNPs) into carboxymethyl cellulose (CMC) and sodium alginate (SA) is reported for the first time. Single step synthesis of carboxymethyl cellulose (CMC) and sodium alginate (SA) biopolymer protected silver nanoparticles (AgNPs) using aniline as a reducing agent under reflux conditions was investigated. The synthesized nanoparticles were characterized by UV-Vis spectrophotometry, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The FESEM results of CMC@AgNPs and SA@AgNPs showed the formation of spherical nanoparticles sized 30-60 nm. Testing of the antibiofilm efficacy of the polymer protected AgNPs against different bacterial strains such as Klebsiella pneumoniae MTCC 4032 and Streptococcus pyogenes MTCC 1924 revealed that the biopolymer protected AgNPs had excellent antibiofilm activity.

  2. Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Im, A.-Rang; Kim, Jee Young; Kim, Hyun-Seok; Cho, Seonho; Park, Youmie; Kim, Yeong Shik

    2013-10-01

    For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

  3. Ag@AgHPW as a plasmonic catalyst for visible-light photocatalytic degradation of environmentally harmful organic pollutants

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, Wenhui; Cao, Minhua, E-mail: caomh@bit.edu.cn; Li, Na

    2013-06-01

    Graphical abstract: Ag@Ag{sub x}H{sub 3−x}PW12O40 (Ag@AgHPW) nanoparticles (NPs), a new visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant, which show a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation. - Highlights: • A new visible-light driven photocatalyst Ag@Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} was designed. • The photocatalyst shows a high activity for the degradation of methyl blue. • The high activity can be ascribed to the synergy of photoexcited AgHPW and Ag. - Abstract: Ag@Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} (Ag@AgHPW) nanoparticles (NPs), a newmore » visible-light driven plasmonic photocatalyst, are prepared by a green photoreduction strategy without the addition of any surfactant. They show strong absorption in the visible region because of the localized surface plasmon resonance (LSPR) of Ag NPs. This plasmonic photocatalyst shows a high activity and stability for the degradation of methyl blue (MB) under visible light irradiation, which could be attributed to the highly synergy of photoexcited Ag{sub x}H{sub 3−x}PW{sub 12}O{sub 40} (AgHPW) and plasmon-excited Ag NPs and the confinement effects at interfaces between polyoxometalates (POMs) and silver. POM anions have redox ability and high photocatalytic activity, whereas Ag NPs could effectively accelerate the separation of electrons and holes, both of which contribute to their high activity.« less

  4. Ag Nanoparticle-Functionalized Open-Ended Freestanding TiO₂ Nanotube Arrays with a Scattering Layer for Improved Energy Conversion Efficiency in Dye-Sensitized Solar Cells.

    PubMed

    Rho, Won-Yeop; Chun, Myeung-Hwan; Kim, Ho-Sub; Kim, Hyung-Mo; Suh, Jung Sang; Jun, Bong-Hyun

    2016-06-15

    Dye-sensitized solar cells (DSSCs) were fabricated using open-ended freestanding TiO₂ nanotube arrays functionalized with Ag nanoparticles (NPs) in the channel to create a plasmonic effect, and then coated with large TiO₂ NPs to create a scattering effect in order to improve energy conversion efficiency. Compared to closed-ended freestanding TiO₂ nanotube array-based DSSCs without Ag or large TiO₂ NPs, the energy conversion efficiency of closed-ended DSSCs improved by 9.21% (actual efficiency, from 5.86% to 6.40%) with Ag NPs, 6.48% (actual efficiency, from 5.86% to 6.24%) with TiO₂ NPs, and 14.50% (actual efficiency, from 5.86% to 6.71%) with both Ag NPs and TiO₂ NPs. By introducing Ag NPs and/or large TiO₂ NPs to open-ended freestanding TiO₂ nanotube array-based DSSCs, the energy conversion efficiency was improved by 9.15% (actual efficiency, from 6.12% to 6.68%) with Ag NPs and 8.17% (actual efficiency, from 6.12% to 6.62%) with TiO₂ NPs, and by 15.20% (actual efficiency, from 6.12% to 7.05%) with both Ag NPs and TiO₂ NPs. Moreover, compared to closed-ended freestanding TiO₂ nanotube arrays, the energy conversion efficiency of open-ended freestanding TiO₂ nanotube arrays increased from 6.71% to 7.05%. We demonstrate that each component-Ag NPs, TiO₂ NPs, and open-ended freestanding TiO₂ nanotube arrays-enhanced the energy conversion efficiency, and the use of a combination of all components in DSSCs resulted in the highest energy conversion efficiency.

  5. Phytofabrication of bioinduced silver nanoparticles for biomedical applications.

    PubMed

    Ahmad, Nabeel; Bhatnagar, Sharad; Ali, Syed Salman; Dutta, Rajiv

    2015-01-01

    Synthesis of nanomaterials holds infinite possibilities as nanotechnology is revolutionizing the field of medicine by its myriad applications. Green synthesis of nanoparticles has become the need of the hour because of its eco-friendly, nontoxic, and economic nature. In this study, leaf extract of Rosa damascena was used as a bioreductant to reduce silver nitrate, leading to synthesis of silver nanoparticles (AgNPs) in a single step, without the use of any additional reducing or capping agents. The synthesized nanoparticles were characterized by the use of UV-visible spectroscopy, fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy. Time-dependent synthesis of AgNPs was studied spectrophotometrically. Synthesized AgNPs were found to possess flower-like spherical structure where individual nanoparticles were of 16 nm in diameter, whereas the agglomerated AgNPs were in the range of 60-80 nm. These biologically synthesized AgNPs exhibited significant antibacterial activity against Gram-negative bacterial species but not against Gram-positive ones (Escherichia coli and Bacillus cereus). Anti-inflammatory and analgesic activities were studied on a Wistar rat model to gauge the impact of AgNPs for a probable role in these applications. AgNPs tested positive for both these activities, although the potency was less as compared to the standard drugs.

  6. Phytofabrication of bioinduced silver nanoparticles for biomedical applications

    PubMed Central

    Ahmad, Nabeel; Bhatnagar, Sharad; Ali, Syed Salman; Dutta, Rajiv

    2015-01-01

    Synthesis of nanomaterials holds infinite possibilities as nanotechnology is revolutionizing the field of medicine by its myriad applications. Green synthesis of nanoparticles has become the need of the hour because of its eco-friendly, nontoxic, and economic nature. In this study, leaf extract of Rosa damascena was used as a bioreductant to reduce silver nitrate, leading to synthesis of silver nanoparticles (AgNPs) in a single step, without the use of any additional reducing or capping agents. The synthesized nanoparticles were characterized by the use of UV-visible spectroscopy, fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy. Time-dependent synthesis of AgNPs was studied spectrophotometrically. Synthesized AgNPs were found to possess flower-like spherical structure where individual nanoparticles were of 16 nm in diameter, whereas the agglomerated AgNPs were in the range of 60–80 nm. These biologically synthesized AgNPs exhibited significant antibacterial activity against Gram-negative bacterial species but not against Gram-positive ones (Escherichia coli and Bacillus cereus). Anti-inflammatory and analgesic activities were studied on a Wistar rat model to gauge the impact of AgNPs for a probable role in these applications. AgNPs tested positive for both these activities, although the potency was less as compared to the standard drugs. PMID:26648715

  7. Silver Nanoparticles: Synthesis, Characterization, Properties, Applications, and Therapeutic Approaches.

    PubMed

    Zhang, Xi-Feng; Liu, Zhi-Guo; Shen, Wei; Gurunathan, Sangiliyandi

    2016-09-13

    Recent advances in nanoscience and nanotechnology radically changed the way we diagnose, treat, and prevent various diseases in all aspects of human life. Silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. AgNPs play an important role in nanoscience and nanotechnology, particularly in nanomedicine. Although several noble metals have been used for various purposes, AgNPs have been focused on potential applications in cancer diagnosis and therapy. In this review, we discuss the synthesis of AgNPs using physical, chemical, and biological methods. We also discuss the properties of AgNPs and methods for their characterization. More importantly, we extensively discuss the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti-cancer activity of AgNPs. In addition, we discuss therapeutic approaches and challenges for cancer therapy using AgNPs. Finally, we conclude by discussing the future perspective of AgNPs.

  8. Silver Nanoparticles: Synthesis, Characterization, Properties, Applications, and Therapeutic Approaches

    PubMed Central

    Zhang, Xi-Feng; Liu, Zhi-Guo; Shen, Wei; Gurunathan, Sangiliyandi

    2016-01-01

    Recent advances in nanoscience and nanotechnology radically changed the way we diagnose, treat, and prevent various diseases in all aspects of human life. Silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. AgNPs play an important role in nanoscience and nanotechnology, particularly in nanomedicine. Although several noble metals have been used for various purposes, AgNPs have been focused on potential applications in cancer diagnosis and therapy. In this review, we discuss the synthesis of AgNPs using physical, chemical, and biological methods. We also discuss the properties of AgNPs and methods for their characterization. More importantly, we extensively discuss the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti-cancer activity of AgNPs. In addition, we discuss therapeutic approaches and challenges for cancer therapy using AgNPs. Finally, we conclude by discussing the future perspective of AgNPs. PMID:27649147

  9. Green synthesis of silver nanoparticles as antibacterial agent using Rhodomyrtus tomentosa acetone extract

    NASA Astrophysics Data System (ADS)

    Voravuthikunchai, Supayang P.; Chorachoo, Julalak; Jaiswal, Lily; Shankar, Shiv

    2013-12-01

    The capability of Rhodomyrtus tomentosa acetone extract (RAE) for the production of silver nanoparticles (AgNPs) has been explored for the first time. Silver nanoparticles with a surface plasmon resonance band centered at 420-430 nm were synthesized by reacting RAE with AgNO3. Reaction time, temperature, concentration of AgNO3 and RAE could accelerate the reduction rate of Ag+ and affect AgNPs size. The nanoparticles were found to be 10-30 nm in size and spherical in shape. XRD data demonstrated crystalline nature of AgNPs dominated by (200) facets. FTIR results showed decrease in intensity of peaks at 3394, 1716 and 1618 cm-1 indicating the involvement of O-H, carbonyl group and C=C stretching with the formation of AgNPs with RAE, respectively. The C-O-C and C-N stretching suggested the presence of many phytochemicals on the surface of the nanoparticles. High negative zeta potential values confirmed the stability of AgNPs in water. In vitro antibacterial activity of AgNPs was tested against Staphylococcus aureus using broth microdilution method. AgNPs capped with RAE demonstrated profound antibacterial activity against the organisms with minimum inhibitory concentration and minimum bactericidal concentration in the range between 3.1-6.2 and 6.2-50 μgmL-1, respectively. The synthesized nanoparticles could be applied as an effective antimicrobial agent against staphylococcal infections.

  10. Low-cost fabrication and polar-dependent switching uniformity of memory devices using alumina interfacial layer and Ag nanoparticle monolayer

    NASA Astrophysics Data System (ADS)

    Xia, Peng; Li, Luman; Wang, Pengfei; Gan, Ying; Xu, Wei

    2017-11-01

    A facile and low-cost process was developed for fabricating write-once-read-many-times (WORM) Cu/Ag NPs/Alumina/Al memory devices, where the alumina passivation layer formed naturally in air at room temperature, whereas the Ag nanoparticle monolayer was in situ prepared through thermal annealing of a 4.5 nm Ag film in air at 150°C. The devices exhibit irreversible transition from initial high resistance (OFF) state to low resistance (ON) state, with ON/OFF ratio of 107, indicating the introduction of Ag nanoparticle monolayer greatly improves ON/OFF ratio by four orders of magnitude. The uniformity of threshold voltages exhibits a polar-dependent behavior, and a narrow range of threshold voltages of 0.40 V among individual devices was achieved upon the forward voltage. The memory device can be regarded as two switching units connected in series. The uniform alumina interfacial layer and the non-uniform distribution of local electric fields originated from Ag nanoparticles might be responsible for excellent switching uniformity. Since silver ions in active layer can act as fast ion conductor, a plausible mechanism relating to the formation of filaments sequentially among the two switching units connected in series is suggested for the polar-dependent switching behavior. Furthermore, we demonstrate both alumina layer and Ag NPs monolayer play essential roles in improving switching parameters based on comparative experiments.

  11. Ag nanoparticle-ZnO nanowire hybrid nanostructures as enhanced and robust antimicrobial textiles via a green chemical approach

    NASA Astrophysics Data System (ADS)

    Li, Zhou; Tang, Haoying; Yuan, Weiwei; Song, Wei; Niu, Yongshan; Yan, Ling; Yu, Min; Dai, Ming; Feng, Siyu; Wang, Menghang; Liu, Tengjiao; Jiang, Peng; Fan, Yubo; Wang, Zhong Lin

    2014-04-01

    A new approach for fabrication of a long-term and recoverable antimicrobial nanostructure/textile hybrid without increasing the antimicrobial resistance is demonstrated. Using in situ synthesized Ag nanoparticles (NPs) anchored on ZnO nanowires (NWs) grown on textiles by a ‘dip-in and light-irradiation’ green chemical method, we obtained ZnONW@AgNP nanocomposites with small-size and uniform Ag NPs, which have shown superior performance for antibacterial applications. These new Ag/ZnO/textile antimicrobial composites can be used for wound dressings and medical textiles for topical and prophylactic antibacterial treatments, point-of-use water treatment to improve the cleanliness of water and antimicrobial air filters to prevent bioaerosols accumulating in ventilation, heating, and air-conditioning systems.

  12. Antibacterial activity of silver nanoparticle-coated fabric and leather against odor and skin infection causing bacteria.

    PubMed

    Velmurugan, Palanivel; Lee, Sang-Myeong; Cho, Min; Park, Jung-Hee; Seo, Sang-Ki; Myung, Hyun; Bang, Keuk-Soo; Oh, Byung-Taek

    2014-10-01

    We present a simple, eco-friendly synthesis of silver and gold nanoparticles using a natural polymer pine gum solution as the reducing and capping agent. The pine gum solution was combined with silver nitrate (AgNO3) or a chloroauric acid (HAuCl4) solution to produce silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs), respectively. The reaction process was simple; formation of the nanoparticles was achieved by autoclaving the silver and gold ions with the pine gum. UV-Vis spectra showed surface plasmon resonance (SPR) for silver and gold nanoparticles at 432 and 539 nm, respectively. The elemental forms of AgNPs and AuNPs were confirmed by energy-dispersive X-ray spectroscopy (EDX). Fourier transform infrared spectroscopy (FTIR) showed the biomolecules present in the pine gum, AgNPs, and AuNPs. Transmission electron microscopy (TEM) images showed the shape and size of AgNPs and AuNPs. The crystalline nature of synthesized AgNPs and AuNPs was confirmed by X-ray crystallography [X-ray diffraction (XRD)]. Application of synthesized AgNPs onto cotton fabrics and leather, in order to evaluate their antibacterial properties against odor- or skin infection-causing bacteria, is also discussed. Among the four tested bacteria, AgNP-coated cotton fabric and leather samples displayed excellent antibacterial activity against Brevibacterium linens.

  13. Anthelmintic activity of silver-extract nanoparticles synthesized from the combination of silver nanoparticles and M. charantia fruit extract.

    PubMed

    Rashid, Md Mamun Or; Ferdous, Jannatul; Banik, Sujan; Islam, Md Rabiul; Uddin, A H M Mazbah; Robel, Fataha Nur

    2016-07-26

    Present study has been conducted to know the anthelmintic activity of polyaniline coated silver nanoparticles (AgNPs) synthesized from Momordica charantia fruit extract. By reduction of AgNO3 in presence of NaBH4, silver nanoparticles were prepared. After mixing silver nanoparticles and extracts, coating was given on nanoparticles using polyaniline. Prepared nanoparticles were characterized by Visual, UV, FTIR spectroscopy, SEM techniques, and TEM analysis. The FTIR results implied that AgNPs were successfully synthesized and capped with bio-compounds present in the extract. The result showed that death times of worm were 35.12 ± 0.5 and 59.3 ± 0.3 minutes for M. charantia extract and Ag-nanoparticles individually. But when these two combined together, paralysis and death time fall drastically which were only 6.16 ± 0.6 and 9.1 ± 0.4 minutes respectively. Albendazole tablet was used as standard, which made worms death in 3.66 ± 0.1 minutes. Ag-Extract NPs showed strong anthelmintic activity against worm. This study has paved the way for further research to design new anthelmintic drug from the combination of M. charantia and AgNPs.

  14. Bioinspired anchoring AgNPs onto micro-nanoporous TiO2 orthopedic coatings: Trap-killing of bacteria, surface-regulated osteoblast functions and host responses.

    PubMed

    Jia, Zhaojun; Xiu, Peng; Li, Ming; Xu, Xuchen; Shi, Yuying; Cheng, Yan; Wei, Shicheng; Zheng, Yufeng; Xi, Tingfei; Cai, Hong; Liu, Zhongjun

    2016-01-01

    The therapeutic applications of silver nanoparticles (AgNPs) against biomedical device-associated infections (BAI), by local delivery, are encountered with risks of detachment, instability and nanotoxicity in physiological milieus. To firmly anchor AgNPs onto modified biomaterial surfaces through tight physicochemical interactions would potentially relieve these concerns. Herein, we present a strategy for hierarchical TiO2/Ag coating, in an attempt to endow medical titanium (Ti) with anticorrosion and antibacterial properties whilst maintaining normal biological functions. In brief, by harnessing the adhesion and reactivity of bioinspired polydopamine, silver nanoparticles were easily immobilized onto peripheral surface and incorporated into interior cavity of a micro/nanoporous TiO2 ceramic coating in situ grown from template Ti. The resulting coating protected the substrate well from corrosion and gave a sustained release of Ag(+) up to 28 d. An interesting germicidal effect, termed "trap-killing", was observed against Staphylococcus aureus strain. The multiple osteoblast responses, i.e. adherence, spreading, proliferation, and differentiation, were retained normal or promoted, via a putative surface-initiated self-regulation mechanism. After subcutaneous implantation for a month, the coated specimens elicited minimal, comparable inflammatory responses relative to the control. Moreover, this simple and safe functionalization strategy manifested a good degree of flexibility towards three-dimensional sophisticated objects. Expectedly, it can become a prospective bench to bedside solution to current challenges facing orthopedics. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Combined efficacy of biologically synthesized silver nanoparticles and different antibiotics against multidrug-resistant bacteria.

    PubMed

    Naqvi, Syed Zeeshan Haider; Kiran, Urooj; Ali, Muhammad Ishtiaq; Jamal, Asif; Hameed, Abdul; Ahmed, Safia; Ali, Naeem

    2013-01-01

    Biological synthesis of nanoparticles is a growing innovative approach that is relatively cheaper and more environmentally friendly than current physicochemical processes. Among various microorganisms, fungi have been found to be comparatively more efficient in the synthesis of nanomaterials. In this research work, extracellular mycosynthesis of silver nanoparticles (AgNPs) was probed by reacting the precursor salt of silver nitrate (AgNO3) with culture filtrate of Aspergillus flavus. Initially, the mycosynthesis was regularly monitored by ultraviolet-visible spectroscopy, which showed AgNP peaks of around 400-470 nm. X-ray diffraction spectra revealed peaks of different intensities with respect to angle of diffractions (2θ) corresponding to varying configurations of AgNPs. Transmission electron micrographs further confirmed the formation of AgNPs in size ranging from 5-30 nm. Combined and individual antibacterial activities of the five conventional antibiotics and AgNPs were investigated against eight different multidrug-resistant bacterial species using the Kirby-Bauer disk-diffusion method. The decreasing order of antibacterial activity (zone of inhibition in mm) of antibiotics, AgNPs, and their conjugates against bacterial group (average) was; ciprofloxacin + AgNPs (23) . imipenem + AgNPs (21) > gentamycin + AgNPs (19) > vancomycin + AgNPs (16) > AgNPs (15) . imipenem (14) > trimethoprim + AgNPs (14) > ciprofloxacin (13) > gentamycin (11) > vancomycin (4) > trimethoprim (0). Overall, the synergistic effect of antibiotics and nanoparticles resulted in a 0.2-7.0 (average, 2.8) fold-area increase in antibacterial activity, which clearly revealed that nanoparticles can be effectively used in combination with antibiotics in order to improve their efficacy against various pathogenic microbes.

  16. Drastic nickel ion removal from aqueous solution by curcumin-capped Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Bettini, S.; Pagano, R.; Valli, L.; Giancane, G.

    2014-08-01

    A completely green synthesis protocol has been adopted to obtain silver nanoaggregates capped by the natural compound (1E, 6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-diene), also known as curcumin. The synthesis has been monitored by infrared, Raman, visible and fluorescence spectroscopies. Characterization confirms that curcumin reduces and caps the nanoparticles, and such a procedure allows its solubility in water and drastically increases curcumin stability. Silver nanoparticles (AgNPs)/curcumin complex has been dispersed in a water solution containing a known nickel ion concentration. After three days, a grey precipitate is observed and nickel concentration in the solution is reduced by about 70%.A completely green synthesis protocol has been adopted to obtain silver nanoaggregates capped by the natural compound (1E, 6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-diene), also known as curcumin. The synthesis has been monitored by infrared, Raman, visible and fluorescence spectroscopies. Characterization confirms that curcumin reduces and caps the nanoparticles, and such a procedure allows its solubility in water and drastically increases curcumin stability. Silver nanoparticles (AgNPs)/curcumin complex has been dispersed in a water solution containing a known nickel ion concentration. After three days, a grey precipitate is observed and nickel concentration in the solution is reduced by about 70%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02583k

  17. Optical, structural and nonlinear optical properties of laser ablation synthesized Ag nanoparticles and photopolymer nanocomposites based on them

    NASA Astrophysics Data System (ADS)

    Zulina, Natalia A.; Pavlovetc, Ilia M.; Baranov, Mikhail A.; Denisyuk, Igor Yu.

    2017-03-01

    In this work Ag nanoparticles (NPs) stable colloid solution were prepared by laser ablation of chemically pure silver rod in liquid monomer isodecyl acrylate (IDA). Sizes of obtained nanoparticles were determined by scanning electron microscope and vary from 27 to 120 nm. Nanocomposites films were prepared from obtained stable colloid solution of AgNPs by photocuring. For aliphatic polymer IDA long molecules cross-linking Diurethane dimethacrylate, 1,6-Hexandiol diacrylate and Tetra (ethylene glycol) diacrylate were used. Prepared nanomaterials exhibit strong third-order nonlinear optical responses, which was estimated by using z-scan technique. The third-order nonlinear optical coefficients of the studied nanocomposites were found to be up to Reχ(3)=1.31×10-5 (esu) and Imχ(3)=7.64×10-5 (esu).

  18. Enhancement of the optical, thermal and electrical properties of PEO/PAM:Li polymer electrolyte films doped with Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Morsi, M. A.; El-Khodary, Sherif A.; Rajeh, A.

    2018-06-01

    Both lithium bromide (LiBr) and biosynthesized silver nanoparticles (Ag NPs) with average size 2-30 nm have been incorporated into the polymeric matrix of polyethylene oxide and polyacrylamide (PEO/PAM) blend by the casting method. FT-IR analysis indicates the formation of hydrogen bond between the blend components. Also, LiBr and Ag NPs interact with the functional groups of PEO/PAM matrix. The results of XRD analysis depict the semi-crystalline nature of these polymer samples and the degree of crystallinity is decreased due to the addition process. The values of optical energy gap from UV-Vis. data are decreased from 3.55 eV for blend to 3.26 for the nanocomposite sample in the indirect transition. LiBr/Ag NPs assist the improvement of the thermal stability of the PEO/PAM blend, as evidenced by TGA and DTA techniques. Upon the addition of LiBr and Ag NPs, an improvement for the conductivity, dielectric permittivity (έ) and dielectric loss (ἕ) of PEO/PAM solid polymer electrolytes are observed. It's clear that the improvement of the electrical conductivity and dielectric parameters for PEO/PAM: Li+/Ag NPs polymer electrolyte system makes it as a promising candidate for solid-state Li battery applications.

  19. Coexistence of silver and titanium dioxide nanoparticles: enhancing or reducing environmental risks?

    PubMed

    Zou, Xiaoyan; Shi, Junpeng; Zhang, Hongwu

    2014-09-01

    Due to their bactericidal and photocatalytic characteristics, silver nanoparticles (Ag NPs) and titanium dioxide nanoparticles (TiO2 NPs) are widely used in the fields of environment and physiology. Once these untreated nanoparticles are released into an aquatic environment and encounter one another, there is more uncertainty about their fate and ecotoxicological risks compared with the single nanoparticles. To expand our knowledge of the health and environmental impacts of nanoparticles, we investigated the possible risk of the co-existence of TiO2 NPs and Ag NPs in an aquatic environment using ciliated protozoa (Tetrahymena pyriformis) as an aquatic animal model. In this study, silver ion (Ag(+)) release and physicochemical properties, as well as their effect on oxidative stress biomarkers, were monitored. Continuous illumination (12,000 lx) led to the 20.0% decrease in Ag(+) release in comparison with dark conditions, while TiO2 NPs and continuous illumination resulted in decreasing the Ag(+) concentration to 64.3% in contrast with Ag NPs-only suspensions. Toxicity tests indicated that different illumination modes exerted distinct effects of TiO2 NPs on the toxicity of Ag NPs: no effects, antagonism and synergism in dark, natural light and continuous light, respectively. In the presence of 1.5mg/L (18.8 μM) TiO2 NPs, the toxicity of 1.5 mg/L (13.9 μM) Ag NPs was reduced by 28.7% and increased by 6.93% in natural light and 12,000 lx of continuous light, respectively. After culturing in 12,000 lx continuous light for 24h, SOD activity of the light control surged to 1.96 times compared to the dark control (P<0.001). TiO2 NPs induced a reduction of CAT activity by an average of (36.1±1.7) % in the light. In the natural light reductions in the toxicity of Ag, NPs decrease Ag(+) concentrations via adsorption of Ag(+) onto TiO2 NPs surfaces. The enhancement of Ag NPs toxicity can contribute to the formation of activated TiO2-Ag NPs complexes in continuous light. The

  20. Eco-friendly approach for nanoparticles synthesis and mechanism behind antibacterial activity of silver and anticancer activity of gold nanoparticles.

    PubMed

    Patil, Maheshkumar Prakash; Kim, Gun-Do

    2017-01-01

    This review covers general information about the eco-friendly process for the synthesis of silver nanoparticles (AgNP) and gold nanoparticles (AuNP) and focuses on mechanism of the antibacterial activity of AgNPs and the anticancer activity of AuNPs. Biomolecules in the plant extract are involved in reduction of metal ions to nanoparticle in a one-step and eco-friendly synthesis process. Natural plant extracts contain wide range of metabolites including carbohydrates, alkaloids, terpenoids, phenolic compounds, and enzymes. A variety of plant species and plant parts have been successfully extracted and utilized for AgNP and AuNP syntheses. Green-synthesized nanoparticles eliminate the need for a stabilizing and capping agent and show shape and size-dependent biological activities. Here, we describe some of the plant extracts involved in nanoparticle synthesis, characterization methods, and biological applications. Nanoparticles are important in the field of pharmaceuticals for their strong antibacterial and anticancer activity. Considering the importance and uniqueness of this concept, the synthesis, characterization, and application of AgNPs and AuNPs are discussed in this review.

  1. Development of a novel tridentate ligand for colorimetric detection of Mn2+ based on AgNPs.

    PubMed

    Wei, Jianyu; Chen, Jinfan; Yue, Guozong; Hu, Liangsheng; Zhao, Danqing; Zhu, Jing; Yang, Luming; Huang, Deshun; Zhao, Pengxiang

    2018-05-09

    A novel tridentate ligand nitrilotris(methylene)tris(1,2,3-triazole)triacetate (NTTTA) has been synthesized by click reaction and followed with ester hydrolysis reaction. The silver nanoparticles (AgNPs) were then modified and stabilized by this ligand, and subsequently been employed for the highly selective and sensitive colorimetric detection of Mn 2+ in aqueous solution. The presence of Mn 2+ can cause the aggregation of AgNPs, which leads to the color change of the dispersion from yellow to brown, as well as the decrease and red-shift of the surface plasmon resonance absorption. The detection limit of Mn 2+ was as approximately 0.5 μM by the naked eyes. UV-vis spectroscopy analysis showed a good linear relationship between the logarithm of the ratios (A 550 /A 395 ) and the concentration of Mn 2+ over the range of 0.05 μM-10 μM, and the LOD was calculated to be 12.6 nM (S/N = 3). The present assay showed good simplicity without the need of adjusting the pH value. The feasibility of this technique was evaluated for successful detection of Mn 2+ in tap water and lake water samples, with good recoveries. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Nanoparticles alloying in liquids: Laser-ablation-generated Ag or Pd nanoparticles and laser irradiation-induced AgPd nanoparticle alloying

    NASA Astrophysics Data System (ADS)

    Semaltianos, N. G.; Chassagnon, R.; Moutarlier, V.; Blondeau-Patissier, V.; Assoul, M.; Monteil, G.

    2017-04-01

    Laser irradiation of a mixture of single-element micro/nanomaterials may lead to their alloying and fabrication of multi-element structures. In addition to the laser induced alloying of particulates in the form of micro/nanopowders in ambient atmosphere (which forms the basis of the field of additive manufacturing technology), another interesting problem is the laser-induced alloying of a mixture of single-element nanoparticles in liquids since this process may lead to the direct fabrication of alloyed-nanoparticle colloidal solutions. In this work, bare-surface ligand-free Ag and Pd nanoparticles in solution were prepared by laser ablation of the corresponding bulk target materials, separately in water. The two solutions were mixed and the mixed solution was laser irradiated for different time durations in order to investigate the laser-induced nanoparticles alloying in liquid. Nanoparticles alloying and the formation of AgPd alloyed nanoparticles takes place with a decrease of the intensity of the surface-plasmon resonance peak of the Ag nanoparticles (at ∼405 nm) with the irradiation time while the low wavelength interband absorption peaks of either Ag or Pd nanoparticles remain unaffected by the irradiation for a time duration even as long as 30 min. The nanoalloys have lattice constants with values between those of the pure metals, which indicates that they consist of Ag and Pd in an approximately 1:1 ratio similar to the atomic composition of the starting mixed-nanoparticle solution. Formation of nanoparticle networks consisting of bimetallic alloyed nanoparticles and nanoparticles that remain as single elements (even after the end of the irradiation), joining together, are also formed. The binding energies of the 3d core electrons of both Ag and Pd nanoparticles shift to lower energies with the irradiation time, which is also a typical characteristic of AgPd alloyed nanoparticles. The mechanisms of nanoparticles alloying and network formation are also

  3. Nanoparticles alloying in liquids: Laser-ablation-generated Ag or Pd nanoparticles and laser irradiation-induced AgPd nanoparticle alloying.

    PubMed

    Semaltianos, N G; Chassagnon, R; Moutarlier, V; Blondeau-Patissier, V; Assoul, M; Monteil, G

    2017-04-18

    Laser irradiation of a mixture of single-element micro/nanomaterials may lead to their alloying and fabrication of multi-element structures. In addition to the laser induced alloying of particulates in the form of micro/nanopowders in ambient atmosphere (which forms the basis of the field of additive manufacturing technology), another interesting problem is the laser-induced alloying of a mixture of single-element nanoparticles in liquids since this process may lead to the direct fabrication of alloyed-nanoparticle colloidal solutions. In this work, bare-surface ligand-free Ag and Pd nanoparticles in solution were prepared by laser ablation of the corresponding bulk target materials, separately in water. The two solutions were mixed and the mixed solution was laser irradiated for different time durations in order to investigate the laser-induced nanoparticles alloying in liquid. Nanoparticles alloying and the formation of AgPd alloyed nanoparticles takes place with a decrease of the intensity of the surface-plasmon resonance peak of the Ag nanoparticles (at ∼405 nm) with the irradiation time while the low wavelength interband absorption peaks of either Ag or Pd nanoparticles remain unaffected by the irradiation for a time duration even as long as 30 min. The nanoalloys have lattice constants with values between those of the pure metals, which indicates that they consist of Ag and Pd in an approximately 1:1 ratio similar to the atomic composition of the starting mixed-nanoparticle solution. Formation of nanoparticle networks consisting of bimetallic alloyed nanoparticles and nanoparticles that remain as single elements (even after the end of the irradiation), joining together, are also formed. The binding energies of the 3d core electrons of both Ag and Pd nanoparticles shift to lower energies with the irradiation time, which is also a typical characteristic of AgPd alloyed nanoparticles. The mechanisms of nanoparticles alloying and network formation are also

  4. A novel glucose biosensor platform based on Ag@AuNPs modified graphene oxide nanocomposite and SERS application.

    PubMed

    Gupta, Vinod Kumar; Atar, Necip; Yola, Mehmet Lütfi; Eryılmaz, Merve; Torul, Hilal; Tamer, Uğur; Boyacı, Ismail Hakkı; Ustündağ, Zafer

    2013-09-15

    This study represents a novel template demonstration of a glucose biosensor based on mercaptophenyl boronic acid (MBA) terminated Ag@AuNPs/graphene oxide (Ag@AuNPs-GO) nanomaterials. The nanocomposites were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) method. The TEM image shows that Ag@AuNPs in the nanocomposite is in the range of diameters of 10-20 nm. The nanocomposite was used for the determination of glucose through the complexation between boronic acid and diol groups of glucose. Thus, a novel glucose biosensor was further fabricated by immobilizing glucose oxidase (GOD) into MBA terminated Ag@AuNPs-GO nanocomposite film (MBA-Ag@AuNPs-GO). The linearity range of glucose was obtained as 2-6mM with detection limit of 0.33 mM. The developed biosensor was also applied successfully for the determination of glucose in blood samples. The concentration value of glucose in blood samples was calculated to be 1.97±0.002 mM from measurements repeated for six times. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Raman gas sensing of modified Ag nanoparticle SERS

    NASA Astrophysics Data System (ADS)

    Myoung, NoSoung; Yoo, Hyung Keun; Hwang, In-Wook

    2014-03-01

    Recent progress in modified Surface Enhanced Raman Scattering (SERS) using Ag nanoparticles makes them promising optical technique for direct gas sensing of interest. However, SERS has been shown to provide sub ppb level detection of the compounds in the vapor phase. The major problem with the sensitivity scaling-up was in the development of fabrication technology for stability and reproducibility of SERS substrates. We report an optimization of 1-propanethiol coated multiple Ag nanoparticle layers on SiO2 substrate as well as new records of real-time, simultaneous vapor phase detection of toluene and 1-2 dichlorobenzene by the radiation of fiber optic coupled 785 nm diode laser and spectrograph. Multiple depositions of Ag NPs were loaded on SiO2 and soaked in 1-propanethiol solution for 24 hours to modify the surface into hydrophobic due to the characteristics of vapor phase of our interests. Raman bands at 1003 cm-1 and 1130 cm-1 for toluene and 12DCB, respectively were compared to 1089 cm-1 and each gas concentration in 1000 mL flask were calculated as a function of each vapor phase ratio. The saturation of toluene and 12DCB were limited only by 800 ppm and the detectable range was 0.6-800 ppm.

  6. Improvement of polypyrrole nanowire devices by plasmonic space charge generation: high photocurrent and wide spectral response by Ag nanoparticle decoration.

    PubMed

    Lee, S-H; Bae, J; Lee, S W; Jang, J-W

    2015-11-07

    In this study, improvement of the opto-electronic properties of non-single crystallized nanowire devices with space charges generated by localized surface plasmon resonance (LSPR) is demonstrated. The photocurrent and spectral response of single polypyrrole (PPy) nanowire (NW) devices are increased by electrostatically attached Ag nanoparticles (Ag NPs). To take advantage of plasmon-exciton coupling in the photocurrent of the device, 80 nm of Ag NPs (454 nm = λmax) were chosen for matching the maximum absorption with PPy NWs (442 nm = λmax). The photocurrent density is remarkably improved, up to 25.3 times (2530%), by the Ag NP decoration onto the PPy NW (PPyAgNPs NW) under blue light (λ = 425-475 nm) illumination. In addition, the PPyAgNPs NW shows a photocurrent decay time twice that of PPy NW, as well as an improved spectral response of the photocurrent. The improved photocurrent efficiency, decay time, and spectral response resulted from the space charges generated by the LSPR of Ag NPs. Furthermore, the increasing exponent (m) of the photocurrent (JPC ∼ V(m)) and finite-differential time domain (FDTD) simulation straightforwardly indicate relatively large plasmonic space charge generation under blue light illumination. These results prove that the performance of non-single crystallized polymer nanowire devices can also be improved by plasmonic enhancement.

  7. Targeted silver nanoparticles for ratiometric cell phenotyping

    NASA Astrophysics Data System (ADS)

    Willmore, Anne-Mari A.; Simón-Gracia, Lorena; Toome, Kadri; Paiste, Päärn; Kotamraju, Venkata Ramana; Mölder, Tarmo; Sugahara, Kazuki N.; Ruoslahti, Erkki; Braun, Gary B.; Teesalu, Tambet

    2016-04-01

    Affinity targeting is used to deliver nanoparticles to cells and tissues. For efficient targeting, it is critical to consider the expression and accessibility of the relevant receptors in the target cells. Here, we describe isotopically barcoded silver nanoparticles (AgNPs) as a tool for auditing affinity ligand receptors in cells. Tumor penetrating peptide RPARPAR (receptor: NRP-1) and tumor homing peptide GKRK (receptor: p32) were used as affinity ligands on the AgNPs. The binding and uptake of the peptide-functionalized AgNPs by cultured PPC-1 prostate cancer and M21 melanoma cells was dependent on the cell surface expression of the cognate peptide receptors. Barcoded peptide-functionalized AgNPs were synthesized from silver and palladium isotopes. The cells were incubated with a cocktail of the barcoded nanoparticles [RPARPAR (R), GKRK (K), and control], and cellular binding and internalization of each type of nanoparticle was assessed by inductively coupled plasma mass spectrometry. The results of isotopic analysis were in agreement with data obtained using optical methods. Using ratiometric measurements, we were able to classify the PPC-1 cell line as mainly NRP-1-positive, with 75 +/- 5% R-AgNP uptake, and the M21 cell line as only p32-positive, with 89 +/- 9% K-AgNP uptake. The isotopically barcoded multiplexed AgNPs are useful as an in vitro ratiometric phenotyping tool and have potential uses in functional evaluation of the expression of accessible homing peptide receptors in vivo.Affinity targeting is used to deliver nanoparticles to cells and tissues. For efficient targeting, it is critical to consider the expression and accessibility of the relevant receptors in the target cells. Here, we describe isotopically barcoded silver nanoparticles (AgNPs) as a tool for auditing affinity ligand receptors in cells. Tumor penetrating peptide RPARPAR (receptor: NRP-1) and tumor homing peptide GKRK (receptor: p32) were used as affinity ligands on the AgNPs. The

  8. Detection and Quantification of Silver Nanoparticles at ...

    EPA Pesticide Factsheets

    The presence of silver nanoparticles (AgNPs) in aquatic environments could potentially cause adverse impacts on ecosystems and human health. However, current understanding of the environmental fate and transport of AgNPs is still limited because their properties in complex environmental samples cannot be accurately determined. In this study, the feasibility of using asymmetric flow field-flow fractionation (AF4) connected online with single particle inductively coupled plasma mass spectrometry (spICPMS) to detect and quantify AgNPs at environmentally relevant concentrations was investigated. The AF4 channel had a thickness of 350 μm and its accumulation wall was a 10 kDa regenerated cellulose membrane. A 0.02% FL-70 surfactant solution was used as an AF4 carrier. With 1.2 mL/min AF4 cross-flow rate, 1.5 mL/min AF4 channel flow rate, and 5 ms spICPMS dwell time, the AF4-spICPMS can detect and quantify 40–80 nm AgNPs, as well as Ag-SiO2 core−shell nanoparticles (51.0 nm diameter Ag core and 21.6 nm SiO2 shell), with good recovery within 30 min. This system was not only effective in differentiating and quantifying different types of AgNPs with similar hydrodynamic diameters, such as in mixtures containing Ag-SiO2 core–shell nanoparticles and 40–80 nm AgNPs, but also suitable for differentiating between 40 nm AgNPs and elevated Ag+ content. The study results indicate that AF4-spICPMS is capable of detecting and quantifying AgNPs and other engineered metal n

  9. Potential Theranostics Application of Bio-Synthesized Silver Nanoparticles (4-in-1 System)

    PubMed Central

    Mukherjee, Sudip; Chowdhury, Debabrata; Kotcherlakota, Rajesh; Patra, Sujata; B, Vinothkumar; Bhadra, Manika Pal; Sreedhar, Bojja; Patra, Chitta Ranjan

    2014-01-01

    In this report, we have designed a simple and efficient green chemistry approach for the synthesis of colloidal silver nanoparticles (b-AgNPs) that is formed by the reduction of silver nitrate (AgNO3) solution using Olax scandens leaf extract. The colloidal b-AgNPs, characterized by various physico-chemical techniques exhibit multifunctional biological activities (4-in-1 system). Firstly, bio-synthesized silver nanoparticles (b-AgNPs) shows enhanced antibacterial activity compared to chemically synthesize silver nanoparticles (c-AgNPs). Secondly, b-AgNPs show anti-cancer activities to different cancer cells (A549: human lung cancer cell lines, B16: mouse melanoma cell line & MCF7: human breast cancer cells) (anti-cancer). Thirdly, these nanoparticles are biocompatible to rat cardiomyoblast normal cell line (H9C2), human umbilical vein endothelial cells (HUVEC) and Chinese hamster ovary cells (CHO) which indicates the future application of b-AgNPs as drug delivery vehicle. Finally, the bio-synthesized AgNPs show bright red fluorescence inside the cells that could be utilized to detect the localization of drug molecules inside the cancer cells (a diagnostic approach). All results together demonstrate the multifunctional biological activities of bio-synthesized AgNPs (4-in-1 system) that could be applied as (i) anti-bacterial & (ii) anti-cancer agent, (iii) drug delivery vehicle, and (iv) imaging facilitator. To the best of our knowledge, there is not a single report of biosynthesized AgNPs that demonstrates the versatile applications (4-in-1 system) towards various biomedical applications. Additionally, a plausible mechanistic approach has been explored for the synthesis of b-AgNPs and its anti-bacterial as well as anti-cancer activity. We strongly believe that bio-synthesized AgNPs will open a new direction towards various biomedical applications in near future. PMID:24505239

  10. Hepatoprotective effect of engineered silver nanoparticles coated bioactive compounds against diethylnitrosamine induced hepatocarcinogenesis in experimental mice.

    PubMed

    Prasannaraj, Govindaraj; Venkatachalam, Perumal

    2017-02-01

    Nanoparticle based drug delivery can rapidly improves the therapeutic potential of anti-cancer agents. The present study focused to evaluate the hepatoprotective activity of silver nanoparticles (AgNPs) synthesized using aqueous extracts of Andrographis paniculata leaves (ApAgNPs) and Semecarpus anacardium nuts (SaAgNPs) against diethylnitrosamine (DEN) induced liver cancer in mice model. The physico-chemical properties of synthesized AgNPs were characterized by Fourier transform infrared (FTIR) spectroscopy, Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED), X-ray Diffraction (XRD), Energy Dispersive X-ray (EDX) spectrum, Zeta potential and Dynamic Light Scattering (DLS) analysis. The surface plasmon resonance (SPR) absorption spectrum revealed a strong peak at 420nm for both SaAgNPs and ApAgNPs. FTIR results exhibited the presence of possible functional groups in the synthesized AgNPs. TEM analysis determined the hexagonal, and spherical shape of the synthesized silver nanoparticles. The XRD and SAED pattern confirmed the crystalline nature and crystalline size of the AgNPs. EDX result clearly showed strong silver signals in the range between 2 and 4keV. Zeta potential measurements indicated a sharp peak at -3.93 and -13.8mV for ApAgNPs and SaAgNPs, respectively. DLS measurement expressed the particle size distribution was 70 and 60nm for ApAgNPs and SaAgNPs, respectively. DEN (20mg/kg b.wt.) was subjected to induce liver cancer in mice for 8weeks and treated with biosynthesized silver nanoparticles. Interestingly, ApAgNPs and SaAgNPs treated DEN induced animal groups show a decreased level of aspartate amino transferase (AST), alanine amino transferase (ALT), serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) activity and elevated level of catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) activity over untreated DEN control

  11. Synthesis, characterization and biocompatibility of silver nanoparticles synthesized from Nigella sativa leaf extract in comparison with chemical silver nanoparticles.

    PubMed

    Amooaghaie, Rayhaneh; Saeri, Mohammad Reza; Azizi, Morteza

    2015-10-01

    Despite the development potential in the field of nanotechnology, there is a concern about possible effects of nanoparticles on the environment and human health. In this study, silver nanoparticles (AgNPs) were synthesized by 'green' and 'chemical' methods. In the wet-chemistry method, sodium borohydrate, sodium citrate and silver nitrate were used as raw materials. Leaf extract of Nigella sativa was used as reducing as well as capping agent to reduce silver nitrate in the green synthesis method. In addition, toxic responses of both synthesized AgNPs were monitored on bone-building stem cells of mice as well as seed germination and seedling growth of six different plants (Lolium, wheat, bean and common vetch, lettuce and canola). In both synthesis methods, the colorless reaction mixtures turned brown and UV-visible spectra confirmed the presence of silver nanoparticles. Scanning electron microscope (SEM) observations revealed the predominance of silver nanosized crystallites and fourier transform infra-red spectroscopy (FTIR) indicated the role of different functional groups in the synthetic process. MTT assay showed cell viability of bone-building stem cells of mice was further in the green AgNPs synthesized using black cumin extract than chemical AgNPs. IC50 (inhibitory concentrations) values for seed germination, root and shoot length for 6 plants in green AgNPs exposures were higher than the chemical AgNPs. These results suggest that cytotoxicity and phytotoxicity of the green synthesized AgNPs were significantly less than wet-chemistry synthesized ones. This study indicated an economical, simple and efficient ecofriendly technique using leaves of N. sativa for synthesis of AgNPs and confirmed that green AgNPs are safer than chemically-synthesized AgNPs. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Low molecular weight chitosan-coated silver nanoparticles are effective for the treatment of MRSA-infected wounds.

    PubMed

    Peng, Yinbo; Song, Chenlu; Yang, Chuanfeng; Guo, Qige; Yao, Min

    2017-01-01

    Silver nanoparticles (AgNPs) are being widely applied as topical wound materials; however, accumulated deposition of silver in the liver, spleen, and other main organs may lead to organ damage and dysfunction. We report here that low molecular weight chitosan-coated silver nanoparticles (LMWC-AgNPs) are effective against methicillin-resistant Staphylococcus aureus (MRSA), have better biocompatibility, and have lower body absorption characteristics when compared with polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) and silver nanoparticles without surface stabilizer (uncoated-AgNPs) in a dorsal MRSA wound infection mouse model. LMWC-AgNPs were synthesized by reducing silver nitrate with low molecular weight chitosan as a stabilizer and reducing agent, while PVP-AgNPs were synthesized using polyvinylpyrrolidone as a stabilizer and ethanol as a reducing agent. AgNPs with different surface stabilizers were identified by UV-visible absorption spectrometry, and particle size was determined by transmission electron microscopy. UV-visible absorption spectra of LMWC-AgNPs, PVP-AgNPs and uncoated-AgNPs were similar and their sizes were in the range of 10-30 nm. In vitro experiments showed that the three types of AgNPs had similar MRSA-killing effects, with obvious effect at 4 μg/mL and 100% effect at 8 μg/mL. Bacteriostatic annulus experiments also showed that all the three types of AgNPs had similar antibacterial inhibitory effect at 10 μg/mL. Cell counting kit-8 assay and Hoechst/propidium iodide (PI) staining showed that LMWC-AgNPs were significantly less toxic to human fibroblasts than PVP-AgNPs and uncoated-AgNPs. Treatment of mice with MRSA wound infection demonstrated that the three types of AgNPs effectively controlled MRSA wound infection and promoted wound healing. After continuous application for 14 days, LMWC-AgNPs-treated mice showed significantly reduced liver dysfunction as demonstrated by the reduced alanine aminotransferase and aspartate

  13. New, rapid method to measure dissolved silver concentration in silver nanoparticle suspensions by aggregation combined with centrifugation

    NASA Astrophysics Data System (ADS)

    Dong, Feng; Valsami-Jones, Eugenia; Kreft, Jan-Ulrich

    2016-09-01

    It is unclear whether the antimicrobial activities of silver nanoparticles (AgNPs) are exclusively mediated by the release of silver ions (Ag+) or, instead, are due to combined nanoparticle and silver ion effects. Therefore, it is essential to quantify dissolved Ag in nanosilver suspensions for investigations of nanoparticle toxicity. We developed a method to measure dissolved Ag in Ag+/AgNPs mixtures by combining aggregation of AgNPs with centrifugation. We also describe the reproducible synthesis of stable, uncoated AgNPs. Uncoated AgNPs were quickly aggregated by 2 mM Ca2+, forming large clusters that could be sedimented in a low-speed centrifuge. At 20,100g, the sedimentation time of AgNPs was markedly reduced to 30 min due to Ca2+-mediated aggregation, confirmed by the measurements of Ag content in supernatants with graphite furnace atomic absorption spectrometry. No AgNPs were detected in the supernatant by UV-Vis absorption spectra after centrifuging the aggregates. Our approach provides a convenient and inexpensive way to separate dissolved Ag from AgNPs, avoiding long ultracentrifugation times or Ag+ adsorption to ultrafiltration membranes.

  14. Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Ajitha, B.; Ashok Kumar Reddy, Y.; Sreedhara Reddy, P.

    2014-07-01

    This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect.

  15. Antibacterial potential of silver nanoparticles synthesized using Madhuca longifolia flower extract as a green resource.

    PubMed

    Patil, Maheshkumar Prakash; Singh, Rahul Dheerendra; Koli, Prashant Bhimrao; Patil, Kalpesh Tumadu; Jagdale, Bapu Sonu; Tipare, Anuja Rajesh; Kim, Gun-Do

    2018-05-25

    The green and one-step synthesis of silver nanoparticles (AgNPs) has been proposed as simple and ecofriendly. In the present study, a flower extract of Madhuca longifolia was used for the reduction of silver nitrate into AgNPs, with phytochemicals from the flower extract as a reducing and stabilizing agents. The synthesized AgNPs were spherical and oval shaped and about 30-50 nm sizes. The appearance of a brown color in the reaction mixture is a primary indication of AgNPs formation, and it was confirmed by observing UV-visible spectroscopy peak at 436 nm. The Energy Dispersive X-ray spectra and X-ray diffraction analysis results together confirm that the synthesized nanoparticles contain silver and silver chloride nanoparticles. The Zeta potential analysis indicates presence of negative charges on synthesized AgNPs. The FT-IR study represents involvement of functional groups in AgNPs synthesis. Synthesized AgNPs shows potential antibacterial activity against Gram-positive and Gram-negative pathogens. M. longifolia flower is a good source for AgNPs synthesis and synthesized AgNPs are applicable as antibacterial agent in therapeutics. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Green synthesis of silver nanoparticles using Prosopis juliflora bark extract: reaction optimization, antimicrobial and catalytic activities.

    PubMed

    Arya, Geeta; Kumari, R Mankamna; Gupta, Nidhi; Kumar, Ajeet; Chandra, Ramesh; Nimesh, Surendra

    2018-08-01

    In the present study, silver nanoparticles (PJB-AgNPs) have been biosynthesized employing Prosopis juliflora bark extract. The biosynthesis of silver nanoparticles was monitored on UV-vis spectrophotometer. The size, charge and polydispersity index (PDI) of PJB-AgNPs were determined using dynamic light scattering (DLS). Different parameters dictating the size of PJB-AgNPs were explored. Nanoparticles biosynthesis optimization studies suggested efficient synthesis of highly dispersed PJB-AgNPs at 25 °C when 9.5 ml of 1 mM AgNO 3 was reduced with 0.5 ml of bark extract for 40 min. Characterization of PJB-AgNPs by SEM showed spherical-shaped nanoparticles with a size range ∼10-50 nm along with a hydrodynamic diameter of ∼55 nm as evaluated by DLS. Further, characterizations were done by FTIR and EDS to evaluate the functional groups and purity of PJB-AgNPs. The antibacterial potential of PJB-AgNPs was tested against E. coli and P. aeruginosa. The PJB-AgNPs remarkably exhibited anticancer activity against A549 cell line as evidenced by Alamar blue assay. The dye degradation activity was also evaluated against 4-nitrophenol that has carcinogenic effect. The results thus obtained suggest application of PJB-AgNPs as antimicrobial, anticancer and catalytic agents.

  17. Global gene response in Saccharomyces cerevisiae exposed to silver nanoparticles.

    PubMed

    Niazi, Javed H; Sang, Byoung-In; Kim, Yeon Seok; Gu, Man Bock

    2011-08-01

    Silver nanoparticles (AgNPs), exhibiting a broad size range and morphologies with highly reactive facets, which are widely applicable in real-life but not fully verified for biosafety and ecotoxicity, were subjected to report transcriptome profile in yeast Saccharomyces cerevisiae. A large number of genes accounted for ∼3% and ∼5% of the genome affected by AgNPs and Ag-ions, respectively. Principal component and cluster analysis suggest that the different physical forms of Ag were the major cause in differential expression profile. Among 90 genes affected by both AgNPs and Ag-ions, metalloprotein mediating high resistance to copper (CUP1-1 and CUP1-2) were strongly induced by AgNPs (∼45-folds) and Ag-ions (∼22-folds), respectively. A total of 17 genes, responsive to chemical stimuli, stress, and transport processes, were differentially induced by AgNPs. The differential expression was also seen with Ag-ions that affected 73 up- and 161 down-regulating genes, and most of these were involved in ion transport and homeostasis. This study provides new information on the knowledge for impact of nanoparticles on living microorganisms that can be extended to other nanoparticles.

  18. Photocatalytic activity of silver oxide capped Ag nanoparticles constructed by air plasma irradiation

    NASA Astrophysics Data System (ADS)

    Fang, Yingcui; Wu, Qingmeng; Li, Huanhuan; Zhang, Bing; Yan, Rong; Chen, Junling; Sun, Mengtao

    2018-04-01

    We construct a kind of structure of silver oxide capped silver nanoparticles (AgNPs) by cost-efficient air plasma irradiation, and study its visible-light driven photocatalytic activity (PA). By controlling the oxidization time, the relationship between the intensity of the localized surface plasmon resonance (LSPR) and the PA is well established. The PA reaches the maximum when the LSPR of AgNPs is nearly completely damped (according to absorption spectra); however, under this condition, the LSPR still works, confirmed with the high efficient selective transformation of p-Aminothiophenol (PATP) to p, p'-dimercaptoazobenzene (DMAB) under visible light. The mechanism of the LSPR damping induced PA improvement is discussed. We not only provide a cost-efficient approach to construct a LSPR strong damping structure but also promote the understanding of LSPR strong damping and its relationship with photocatalysis.

  19. Plant-Mediated Synthesis of Silver Nanoparticles: Their Characteristic Properties and Therapeutic Applications

    NASA Astrophysics Data System (ADS)

    Chung, Ill-Min; Park, Inmyoung; Seung-Hyun, Kim; Thiruvengadam, Muthu; Rajakumar, Govindasamy

    2016-01-01

    Interest in "green nanotechnology" in nanoparticle biosynthesis is growing among researchers. Nanotechnologies, due to their physicochemical and biological properties, have applications in diverse fields, including drug delivery, sensors, optoelectronics, and magnetic devices. This review focuses on the green synthesis of silver nanoparticles (AgNPs) using plant sources. Green synthesis of nanoparticles is an eco-friendly approach, which should be further explored for the potential of different plants to synthesize nanoparticles. The sizes of AgNPs are in the range of 1 to 100 nm. Characterization of synthesized nanoparticles is accomplished through UV spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and scanning electron microscopy. AgNPs have great potential to act as antimicrobial agents. The green synthesis of AgNPs can be efficiently applied for future engineering and medical concerns. Different types of cancers can be treated and/or controlled by phytonanotechnology. The present review provides a comprehensive survey of plant-mediated synthesis of AgNPs with specific focus on their applications, e.g., antimicrobial, antioxidant, and anticancer activities.

  20. Anisotropic silver nanoparticles as filler for the formation of hybrid nanocomposites

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vodnik, Vesna V., E-mail: vodves@vinca.rs; Šaponjić, Zoran, E-mail: saponjic@vinca.rs; Džunuzović, Jasna V., E-mail: jasnav2002@googlemail.com

    2013-01-15

    Graphical abstract: Display Omitted Highlights: ► Prismatic and plate-like Ag nanoparticles were used as a precursors for preparation Ag/poly(vinyl alcohol) nanocomposite films. ► Results showed that the degree of crystallinity of the polymer decreases with Ag nanoparticles content. ► The presence of Ag nanoparticles in PVA induces higher thermo-oxidative stability with respect to PVA. -- Abstract: Prismatic and plate-like silver nanoparticles (Ag NPs) were synthesized according to the seed-mediated method. These particles were used as precursors for preparation of homogenous, transparent and colored Ag/poly(vinyl alcohol) (PVA) nanocomposite films with different concentrations of Ag by solution-casting technique. Optical and structural characterizationmore » of these nanocomposites includes UV–visible spectroscopy, X-ray diffraction (XRD), FTIR spectroscopy and SEM measurements. Further, the effect of embedded nanoparticles on the thermal properties of the PVA matrix was studied. The value of the glass transition temperature of polymer is found to increase after embedding Ag NPs. Comparison of thermal properties of pure PVA and nanocomposite films showed that the thermo-oxidative stability of polymer slightly increased in the presence of Ag NPs. Furthermore, the effect of the Ag NPs on the crystallinity of polymer was also observed.« less

  1. Surface modification of nanoporous alumina layers by deposition of Ag nanoparticles. Effect of alumina pore diameter on the morphology of silver deposit and its influence on SERS activity

    NASA Astrophysics Data System (ADS)

    Pisarek, Marcin; Nowakowski, Robert; Kudelski, Andrzej; Holdynski, Marcin; Roguska, Agata; Janik-Czachor, Maria; Kurowska-Tabor, Elżbieta; Sulka, Grzegorz D.

    2015-12-01

    Self-organized Al2O3 nanoporous/nanotubular (Al2O3-NP) oxide layers decorated with silver nanoparticles (Ag-NPs) exhibiting specific properties may serve as attractive SERS substrates for investigating the interactions between an adsorbate and adsorbent, or as stable platforms for detecting various organic compounds. This article presents the influence of the size of the alumina nanopores with a deposit of silver nanoparticles obtained by the magnetron sputtering technique on the morphology of silver film. Moreover, the effect of pore diameter on the intensity of SERS spectra in Ag-NPs/Al2O3-NP/Al composites has also been estimated. For such investigations we used pyridine as a probe molecule, since it has a large cross-section for Raman scattering. To characterize the morphology of the composite oxide layer Ag-NPs/Al2O3-NP/Al, before and after deposition of Ag-NPs by PVD methods (Physical Vapor Deposition), we used scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface analytical technique of surface-enhanced Raman spectroscopy (SERS) was used to investigate the surface activity of the composite. The results obtained show that, for a carefully controlled amount of Ag (0.020 mg/cm2 - deposited on the top of alumina nanopores whose average size varies from ∼86 nm up to ∼320 nm) in the composites investigated, pore size significantly affects SERS enhancement. We obtained distinctly higher intensities of SERS spectra for substrates with an Ag-NPs deposit having a larger diameter of the alumina nanopores. AFM results suggest that both the lateral and perpendicular distribution of Ag-NPs within and on the top of the largest pores is responsible for the highest SERS activity of the resulting Ag-NPs/Al2O3-NP/Al composite layer, since it produces a variety of cavities and slits which function as resonators for the adsorbed molecules. The Ag-NPs/MeOx-NP/Me composite layers obtained ensure a good reproducibility of the SERS measurements.

  2. Combined use of vancomycin-modified Ag-coated magnetic nanoparticles and secondary enhanced nanoparticles for rapid surface-enhanced Raman scattering detection of bacteria.

    PubMed

    Wang, Chongwen; Gu, Bing; Liu, Qiqi; Pang, Yuanfeng; Xiao, Rui; Wang, Shengqi

    2018-01-01

    Pathogenic bacteria have always been a significant threat to human health. The detection of pathogens needs to be rapid, accurate, and convenient. We present a sensitive surface-enhanced Raman scattering (SERS) biosensor based on the combination of vancomycin-modified Ag-coated magnetic nanoparticles (Fe 3 O 4 @Ag-Van MNPs) and Au@Ag nanoparticles (NPs) that can effectively capture and discriminate bacterial pathogens from solution. The high-performance Fe 3 O 4 @Ag MNPs were modified with vancomycin and used as bacteria capturer for magnetic separation and enrichment. The modified MNPS were found to exhibit strong affinity with a broad range of Gram-positive and Gram-negative bacteria. After separating and rinsing bacteria, Fe 3 O 4 @Ag-Van MNPs and Au@Ag NPs were synergistically used to construct a very large number of hot spots on bacteria cells, leading to ultrasensitive SERS detection. The dominant merits of our dual enhanced strategy included high bacterial-capture efficiency (>65%) within a wide pH range (pH 3.0-11.0), a short assay time (<30 min), and a low detection limit (5×10 2 cells/mL). Moreover, the spiked tests show that this method is still valid in milk and blood samples. Owing to these capabilities, the combined system enabled the sensitive and specific discrimination of different pathogens in complex solution, as verified by its detection of Gram-positive bacterium Escherichia coli , Gram-positive bacterium Staphylococcus aureus , and methicillin-resistant S. aureus . This method has great potential for field applications in food safety, environmental monitoring, and infectious disease diagnosis.

  3. Green Synthesis of Silver Nanoparticles, Their Characterization, Application and Antibacterial Activity †

    PubMed Central

    Okafor, Florence; Janen, Afef; Kukhtareva, Tatiana; Edwards, Vernessa; Curley, Michael

    2013-01-01

    Our research focused on the production, characterization and application of silver nanoparticles (AgNPs), which can be utilized in biomedical research and environmental cleaning applications. We used an environmentally friendly extracellular biosynthetic technique for the production of the AgNPs. The reducing agents used to produce the nanoparticles were from aqueous extracts made from the leaves of various plants. Synthesis of colloidal AgNPs was monitored by UV-Visible spectroscopy. The UV-Visible spectrum showed a peak between 417 and 425 nm corresponding to the Plasmon absorbance of the AgNPs. The characterization of the AgNPs such as their size and shape was performed by Atom Force Microscopy (AFM), and Transmission Electron Microscopy (TEM) techniques which indicated a size range of 3 to 15 nm. The anti-bacterial activity of AgNPs was investigated at concentrations between 2 and 15 ppm for Gram-negative and Gram-positive bacteria. Staphylococcus aureus and Kocuria rhizophila, Bacillus thuringiensis (Gram-positive organisms); Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhimurium (Gram-negative organisms) were exposed to AgNPs using Bioscreen C. The results indicated that AgNPs at a concentration of 2 and 4 ppm, inhibited bacterial growth. Preliminary evaluation of cytotoxicity of biosynthesized silver nanoparticles was accomplished using the InQ™ Cell Research System instrument with HEK 293 cells. This investigation demonstrated that silver nanoparticles with a concentration of 2 ppm and 4 ppm were not toxic for human healthy cells, but inhibit bacterial growth. PMID:24157517

  4. Characterisation of biosynthesised silver nanoparticles by scanning electrochemical microscopy (SECM) and voltammetry.

    PubMed

    Battistel, Dario; Baldi, Franco; Gallo, Michele; Faleri, Claudia; Daniele, Salvatore

    2015-01-01

    Silver nanoparticles (AgNPs) were biosynthesised by a Klebsiella oxytoca strain BAS-10, which, during its growth, is known to produce a branched exopolysaccharide (EPS). Klebsiella oxytoca cultures, treated with AgNO3 and grown under either aerobic or anaerobic conditions, produced silver nanoparticles embedded in EPS (AgNPs-EPS) containing different amounts of Ag(0) and Ag(I) forms. The average size of the AgNPs-EPS was determined by transmission electron microscopy, while the relative abundance of Ag(0)- or Ag(I)-containing AgNPs-EPS was established by scanning electrochemical microscopy (SECM). Moreover, the release of silver(I) species from the various types of AgNPs-EPS was investigated by combining SECM with anodic stripping voltammetry. These measurements allowed obtaining information on the kinetic of silver ions release from AgNPs-EPS and their concentration profiles at the substrate/water interface. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Analysis of silver nanoparticles in antimicrobial products using surface-enhanced Raman spectroscopy (SERS).

    PubMed

    Guo, Huiyuan; Zhang, Zhiyun; Xing, Baoshan; Mukherjee, Arnab; Musante, Craig; White, Jason C; He, Lili

    2015-04-07

    Silver nanoparticles (AgNPs) are the most commonly used nanoparticles in consumer products. Concerns over human exposure to and risk from these particles have resulted in increased interest in novel strategies to detect AgNPs. This study investigated the feasibility of surface-enhanced Raman spectroscopy (SERS) as a method for the detection and quantification of AgNPs in antimicrobial products. By using ferbam (ferric dimethyl-dithiocarbamate) as an indicator molecule that binds strongly onto the nanoparticles, AgNPs detection and discrimination were achieved based on the signature SERS response of AgNPs-ferbam complexes. SERS response with ferbam was distinct for silver ions, silver chloride, silver bulk particles, and AgNPs. Two types of AgNPs with different coatings, citrate and polyvinylpirrolidone (PVP), both showed strong interactions with ferbam and induced strong SERS signals. SERS was effectively applicable for detecting Ag particles ranging from 20 to 200 nm, with the highest signal intensity in the 60-100 nm range. A linear relationship (R(2) = 0.9804) between Raman intensity and citrate-AgNPs concentrations (60 nm; 0-20 mg/L) indicates the potential for particle quantification. We also evaluated SERS detection of AgNPs in four commercially available antimicrobial products. Combined with ICP-MS and TEM data, the results indicated that the SERS response is primarily dependent on size, but also affected by AgNPs concentration. The findings demonstrate that SERS is a promising analytical platform for studying environmentally relevant levels of AgNPs in consumer products and related matrices.

  6. Biological Mechanism of Silver Nanoparticle Toxicity

    NASA Astrophysics Data System (ADS)

    Armstrong, Najealicka Nicole

    Silver nanoparticles (AgNPs), like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities above that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, these investigations were attempted to monitor the effects of AgNPs at a non-lethal concentration on wild type Drosophila melanogaster by exposing them to nanoparticles throughout their development. All adult flies raised in AgNP doped food indicated that of not more than 50 mg/L had no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised after AgNP feeding. The determination of the amount of free ionic silver (Ag+) indicated that the observed biological effects had resulted from the AgNPs and not from Ag+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, were decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Furthermore, copper supplementation restored the loss of AgNP induced demelanization, and the reduction of functional Ctr1 in Ctr1 heterozygous mutants caused the flies to be resistant to demelanization. Consequently, these studies proposed a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explained the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, these investigations demonstrated that Drosophila, an established genetic model system, can be well utilized for further

  7. Sampling for silver nanoparticles in aqueous media using a rotating disk electrode: evidence for selective sampling of silver nanoparticles in the presence of ionic silver.

    PubMed

    Steinberg, Spencer; Hodge, Vernon; Schumacher, Brian; Sovocool, Wayne

    2017-03-01

    Amendment of a carbon paste electrode consisting of graphite and Nujol®, with a variety of organic and inorganic materials, allows direct adsorption of silver nanoparticles (AgNPs) from aqueous solution in either open or close circuit modes. The adsorbed AgNPs are detected by stripping voltammetry. Detection limits of less than 1 ppb Ag are achievable with a rotating disk system. More than one silver peak was apparent in many of the stripping voltammograms. The appearance of multiple peaks could be due to different species of silver formed upon stripping or variation in the state of aggregation or size of nanoparticles. With most of these packing materials, dissolved Ag + was also extracted from aqueous solution, but, with a packing material made with Fe(II,III) oxide nanoparticles, only AgNPs were extracted. Therefore, it is the best candidate for determination of metallic AgNPs in aqueous environmental samples without interference from Ag + .

  8. Preparation of silver nanoparticles fabrics against multidrug-resistant bacteria

    NASA Astrophysics Data System (ADS)

    Hanh, Truong Thi; Thu, Nguyen Thi; Hien, Nguyen Quoc; An, Pham Ngoc; Loan, Truong Thi Kieu; Hoa, Phan Thi

    2016-04-01

    The silver nanoparticles (AgNPs)/peco fabrics were prepared by immobilization of AgNPs on fabrics in which AgNPs were synthesized by γ-irradiation of the 10 mM AgNO3 chitosan solution at the dose of 17.6 kGy. The AgNPs size has been estimated to be about 11 nm from TEM image. The AgNPs content onto peco fabrics was of 143±6 mg/kg at the initial AgNPs concentration of 100 ppm. The AgNPs colloidal solution was characterized by UV-vis spectroscopy and TEM image. The antibacterial activity of AgNPs/peco fabrics after 60 washings against Staphylococcus aureus and Klebsiella pneumoniae was found to be over 99%. Effects of AgNPs fabics on multidrug-resistant pathogens from the clinical specimens were also tested.

  9. Development of nitrocellulose membrane filters impregnated with different biosynthesized silver nanoparticles applied to water purification.

    PubMed

    Fernández, Jorge G; Almeida, César A; Fernández-Baldo, Martín A; Felici, Emiliano; Raba, Julio; Sanz, María I

    2016-01-01

    Bactericidal water filters were developed. For this purpose, nitrocellulose membrane filters were impregnated with different biosynthesized silver nanoparticles. Silver nanoparticles (AgNPs) from Aspergillus niger (AgNPs-Asp), Cryptococcus laurentii (AgNPs-Cry) and Rhodotorula glutinis (AgNPs-Rho) were used for impregnating nitrocellulose filters. The bactericidal properties of these nanoparticles against Escherichia coli, Enterococcus faecalis and Pseudomona aeruginosa were successfully demonstrated. The higher antimicrobial effect was observed for AgNPs-Rho. This fact would be related not only to the smallest particles, but also to polysaccharides groups that surrounding these particles. Moreover, in this study, complete inhibition of bacterial growth was observed on nitrocellulose membrane filters impregnated with 1 mg L(-1) of biosynthesized AgNPs. This concentration was able to reduce the bacteria colony count by over 5 orders of magnitude, doing suitable for a water purification device. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. In vitro evaluation of acaricidal activity of novel green silver nanoparticles against deltamethrin resistance Rhipicephalus (Boophilus) microplus.

    PubMed

    Avinash, B; Venu, R; Alpha Raj, M; Srinivasa Rao, K; Srilatha, Ch; Prasad, T N V K V

    2017-04-15

    An investigation was undertaken to study, for the first time, in vitro acaricidal activity of green silver nanoparticles on deltamethrin resistance Rhipicephalus (Boophilus) microplus. The compounds tested were neem coated silver nanoparticles (N-Ag NPs), deltamethrin neem coated silver nanoparticles (DN-Ag NPs), 2, 3 dehydrosalannol (2,3 DHS), 2, 3 DHS coated silver nanoparticles (2, 3-DHS-Ag NPs), Quercetin dihydrate (QDH) and QDH coated silver nanoparticles (QDH-Ag NPs). Also included in this study, for the purpose of comparison, were neem leaf extract (NLE), silver nitrate (AgNO 3 ) and deltamethrin (D). Acaricidal activity on larvae and adults of R. (B.) microplus was tested by larval packet test (LPT) and adult immersion test (AIT) respectively. In the LPT, 100% mortality was obtained at concentrations (ppm) of 360, 6000, 260, 200, 50, 300, 85, 600 and 200 for the compounds, D, NLE, Ag NO 3 , N-Ag NPs, DN-Ag NPs, 2, 3 DHS, 2, 3 DHS-Ag NPs, QDH, QDH-Ag NPs respectively. In AIT, the proportions of mortality and oviposition inhibition were proportionate but the reproductive index was inversely proportional to the concentration of the compounds used. The effect of DN-Ag NPs on mortality was the highest (93.33%) at 50ppm concentration. The mean reproductive index (0.01) and oviposition inhibition (99.16%) values were statistically significant when compared to control group. DN-Ag NPs showed significantly (P<0.05) lower LC 50 (3.87ppm; 21.95ppm) and LC 99 (53.05ppm; 90.06ppm) values against both the larvae and adults of R. (B.) microplus. The oviposition inhibiting ability of various compounds was determined to assess the reproductive performance of adult female ticks. The DN-Ag NPs had potent oviposition inhibitory activity with significantly lower IC 50 and IC 99 values compared to the rest of the treatments at 0.034 and 51.07ppm respectively. These results showed that the DN-Ag NPs had significant acaricidal activity against R. (B.) microplus. Copyright © 2017

  11. Speciation Matters: Bioavailability of Silver and Silver Sulfide Nanoparticles to Alfalfa (Medicago sativa).

    PubMed

    Stegemeier, John P; Schwab, Fabienne; Colman, Benjamin P; Webb, Samuel M; Newville, Matthew; Lanzirotti, Antonio; Winkler, Christopher; Wiesner, Mark R; Lowry, Gregory V

    2015-07-21

    Terrestrial crops are directly exposed to silver nanoparticles (Ag-NPs) and their environmentally transformed analog silver sulfide nanoparticles (Ag2S-NPs) when wastewater treatment biosolids are applied as fertilizer to agricultural soils. This leads to a need to understand their bioavailability to plants. In the present study, the mechanisms of uptake and distribution of silver in alfalfa (Medicago sativa) were quantified and visualized upon hydroponic exposure to Ag-NPs, Ag2S-NPs, and AgNO3 at 3 mg total Ag/L. Total silver uptake was measured in dried roots and shoots, and the spatial distribution of elements was investigated using transmission electron microscopy (TEM) and synchrotron-based X-ray imaging techniques. Despite large differences in release of Ag(+) ions from the particles, Ag-NPs, Ag2S-NPs, and Ag(+) became associated with plant roots to a similar degree, and exhibited similarly limited (<1%) amounts of translocation of silver into the shoot system. X-ray fluorescence (XRF) mapping revealed differences in the distribution of Ag into roots for each treatment. Silver nanoparticles mainly accumulated in the (columella) border cells and elongation zone, whereas Ag(+) accumulated more uniformly throughout the root. In contrast, Ag2S-NPs remained largely adhered to the root exterior, and the presence of cytoplasmic nano-SixOy aggregates was observed. Exclusively in roots exposed to particulate silver, NPs smaller than the originally dosed NPs were identified by TEM in the cell walls. The apparent accumulation of Ag in the root apoplast determined by XRF, and the presence of small NPs in root cell walls suggests uptake of partially dissolved NPs and translocation along the apoplast.

  12. Improvement of the Laser-Induced Breakdown Spectroscopy method sensitivity by the usage of combination of Ag-nanoparticles and vacuum conditions

    NASA Astrophysics Data System (ADS)

    Sládková, Lucia; Prochazka, David; Pořízka, Pavel; Škarková, Pavlína; Remešová, Michaela; Hrdlička, Aleš; Novotný, Karel; Čelko, Ladislav; Kaiser, Jozef

    2017-01-01

    In this work we studied the effect of vacuum (low pressure) conditions on the behavior of laser-induced plasma (LIP) created on a sample surface covered with silver nanoparticles (Ag-NPs), i.e. Nanoparticles-Enhanced Laser-Induced Breakdown Spectroscopy (NELIBS) experiment in a vacuum. The focus was put on the step by step optimization of the measurement parameters, such as energy of the laser pulse, temporally resolved detection, ambient pressure, and different content of Ag-NPs applied on the sample surface. The measurement parameters were optimized in order to achieve the greatest enhancement represented as the signal-to-noise ratio (SNR) of NELIBS signal to the SNR of LIBS signal. The presence of NPs involved in the ablation process enhances LIP intensity; hence the improvement in the analytical sensitivity was yielded. A leaded brass standard was analyzed with the emphasis on the signal enhancement of Pb traces. We gained enhancement by a factor of four. Although the low pressure had no significant influence on the LIP signal enhancement compared to that under ambient conditions, the SNR values were noticeably improved with the implementation of the NPs.

  13. Antimicrobial polyethyleneimine-silver nanoparticles in a stable colloidal dispersion.

    PubMed

    Lee, Hyun Ju; Lee, Se Guen; Oh, Eun Jung; Chung, Ho Yun; Han, Sang Ik; Kim, Eun Jung; Seo, Song Yi; Ghim, Han Do; Yeum, Jeong Hyun; Choi, Jin Hyun

    2011-11-01

    Excellent colloidal stability and antimicrobial activity are important parameters for silver nanoparticles (AgNPs) in a range of biomedical applications. In this study, polyethyleneimine (PEI)-capped silver nanoparticles (PEI-AgNPs) were synthesized in the presence of sodium borohydride (NaBH(4)) and PEI at room temperature. The PEI-AgNPs had a positive zeta potential of approximately +49 mV, and formed a stable nanocolloid against agglomeration due to electrostatic repulsion. The particle size and hydrodynamic cluster size showed significant correlations with the amount of PEI and NaBH(4). PEI-AgNPs and even PEI showed excellent antimicrobial activity against Staphylococus aureus and Klebsiella pneumoniae. The cytotoxic effects of PEI and PEI-AgNPs were confirmed by an evaluation of the cell viability. The results suggest that the amount of PEI should be minimized to the level that maintains the stability of PEI-AgNPs in a colloidal dispersion. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity.

    PubMed

    Ajitha, B; Ashok Kumar Reddy, Y; Sreedhara Reddy, P

    2014-07-15

    This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Silver Nanoparticle-Mediated Cellular Responses in Various Cell Lines: An in Vitro Model

    PubMed Central

    Zhang, Xi-Feng; Shen, Wei; Gurunathan, Sangiliyandi

    2016-01-01

    Silver nanoparticles (AgNPs) have attracted increased interest and are currently used in various industries including medicine, cosmetics, textiles, electronics, and pharmaceuticals, owing to their unique physical and chemical properties, particularly as antimicrobial and anticancer agents. Recently, several studies have reported both beneficial and toxic effects of AgNPs on various prokaryotic and eukaryotic systems. To develop nanoparticles for mediated therapy, several laboratories have used a variety of cell lines under in vitro conditions to evaluate the properties, mode of action, differential responses, and mechanisms of action of AgNPs. In vitro models are simple, cost-effective, rapid, and can be used to easily assess efficacy and performance. The cytotoxicity, genotoxicity, and biocompatibility of AgNPs depend on many factors such as size, shape, surface charge, surface coating, solubility, concentration, surface functionalization, distribution of particles, mode of entry, mode of action, growth media, exposure time, and cell type. Cellular responses to AgNPs are different in each cell type and depend on the physical and chemical nature of AgNPs. This review evaluates significant contributions to the literature on biological applications of AgNPs. It begins with an introduction to AgNPs, with particular attention to their overall impact on cellular effects. The main objective of this review is to elucidate the reasons for different cell types exhibiting differential responses to nanoparticles even when they possess similar size, shape, and other parameters. Firstly, we discuss the cellular effects of AgNPs on a variety of cell lines; Secondly, we discuss the mechanisms of action of AgNPs in various cellular systems, and try to elucidate how AgNPs interact with different mammalian cell lines and produce significant effects; Finally, we discuss the cellular activation of various signaling molecules in response to AgNPs, and conclude with future perspectives

  16. Green synthesis of gold and silver nanoparticles from Cannabis sativa (industrial hemp) and their capacity for biofilm inhibition

    PubMed Central

    Singh, Priyanka; Pandit, Santosh; Garnæs, Jørgen; Tunjic, Sanja; Mokkapati, Venkata RSS; Sultan, Abida; Thygesen, Anders; Mackevica, Aiga; Mateiu, Ramona Valentina; Daugaard, Anders Egede; Baun, Anders; Mijakovic, Ivan

    2018-01-01

    Background Cannabis sativa (hemp) is a source of various biologically active compounds, for instance, cannabinoids, terpenes and phenolic compounds, which exhibit antibacterial, antifungal, anti-inflammatory and anticancer properties. With the purpose of expanding the auxiliary application of C. sativa in the field of bio-nanotechnology, we explored the plant for green and efficient synthesis of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs). Methods and results The nanoparticles were synthesized by utilizing an aqueous extract of C. sativa stem separated into two different fractions (cortex and core [xylem part]) without any additional reducing, stabilizing and capping agents. In the synthesis of AuNPs using the cortex enriched in bast fibers, fiber-AuNPs (F-AuNPs) were achieved. When using the core part of the stem, which is enriched with phenolic compounds such as alkaloids and cannabinoids, core-AuNPs (C-AuNPs) and core-AgNPs (C-AgNPs) were formed. Synthesized nanoparticles were character-ized by UV–visible analysis, transmission electron microscopy, atomic force microscopy, dynamic light scattering, Fourier transform infrared, and matrix-assisted laser desorption/ionization time-of-flight. In addition, the stable nature of nanoparticles has been shown by thermogravimetric analysis and inductively coupled plasma mass spectrometry (ICP-MS). Finally, the AgNPs were explored for the inhibition of Pseudomonas aeruginosa and Escherichia coli biofilms. Conclusion The synthesized nanoparticles were crystalline with an average diameter between 12 and 18 nm for F-AuNPs and C-AuNPs and in the range of 20–40 nm for C-AgNPs. ICP-MS analysis revealed concentrations of synthesized nanoparticles as 0.7, 4.5 and 3.6 mg/mL for F-AuNPs, C-AuNPs and C-AgNPs, respectively. Fourier transform infrared spectroscopy revealed the presence of flavonoids, cannabinoids, terpenes and phenols on the nanoparticle surface, which could be responsible for reducing the salts to

  17. Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties

    NASA Astrophysics Data System (ADS)

    Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

    2015-03-01

    Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells.

  18. Ag nanoparticles-decorated ZnO nanorod array on a mechanical flexible substrate with enhanced optical and antimicrobial properties.

    PubMed

    Chen, Yi; Tse, Wai Hei; Chen, Longyan; Zhang, Jin

    2015-01-01

    Heteronanostructured zinc oxide nanorod (ZnO NR) array are vertically grown on polydimethylsiloxane (PDMS) through a hydrothermal method followed by an in situ deposition of silver nanoparticles (Ag NPs) through a photoreduction process. The Ag-ZnO heterostructured nanorods on PDMS are measured with an average diameter of 160 nm and an average length of 2 μm. ZnO NRs measured by high-resolution transmission electron microscope (HRTEM) shows highly crystalline with a lattice fringe of 0.255 nm, which corresponds to the (0002) planes in ZnO crystal lattice. The average diameter of the Ag NPs in situ deposited on the ZnO NRs is estimated at 22 ± 2 nm. As compared to the bare ZnO NRs, the heterostructured Ag-ZnO nanorod array shows enhanced ultraviolet (UV) absorption at 440 nm, and significant emission in the visible region (λem = 542 nm). In addition, the antimicrobial efficiency of Ag-ZnO heterostructured nanorod array shows obvious improvement as compared to bare ZnO nanorod array. The cytotoxicity of ZnO nanorod array with and without Ag NPs was studied by using 3 T3 mouse fibroblast cell line. No significant toxic effect is imposed on the cells.

  19. Curcumin modified silver nanoparticles for highly efficient inhibition of respiratory syncytial virus infection

    NASA Astrophysics Data System (ADS)

    Yang, Xiao Xi; Li, Chun Mei; Huang, Cheng Zhi

    2016-01-01

    Interactions between nanoparticles and viruses have attracted increasing attention due to the antiviral activity of nanoparticles and the resulting possibility to be employed as biomedical interventions. In this contribution, we developed a very simple route to prepare uniform and stable silver nanoparticles (AgNPs) with antiviral properties by using curcumin, which is a member of the ginger family isolated from rhizomes of the perennial herb Curcuma longa and has a wide range of biological activities like antioxidant, antifungal, antibacterial and anti-inflammatory effects, and acts as reducing and capping agents in this synthetic route. The tissue culture infectious dose (TCID50) assay showed that the curcumin modified silver nanoparticles (cAgNPs) have a highly efficient inhibition effect against respiratory syncytial virus (RSV) infection, giving a decrease of viral titers about two orders of magnitude at the concentration of cAgNPs under which no toxicity was found to the host cells. Mechanism investigations showed that cAgNPs could prevent RSV from infecting the host cells by inactivating the virus directly, indicating that cAgNPs are a novel promising efficient virucide for RSV.Interactions between nanoparticles and viruses have attracted increasing attention due to the antiviral activity of nanoparticles and the resulting possibility to be employed as biomedical interventions. In this contribution, we developed a very simple route to prepare uniform and stable silver nanoparticles (AgNPs) with antiviral properties by using curcumin, which is a member of the ginger family isolated from rhizomes of the perennial herb Curcuma longa and has a wide range of biological activities like antioxidant, antifungal, antibacterial and anti-inflammatory effects, and acts as reducing and capping agents in this synthetic route. The tissue culture infectious dose (TCID50) assay showed that the curcumin modified silver nanoparticles (cAgNPs) have a highly efficient inhibition

  20. The effect of nanoparticles (NPs) on sorption and suspension stability of technology critical elements (TCEs) in soil/sand solutions.

    NASA Astrophysics Data System (ADS)

    Dror, I.; Stepka, Z.; Berkowitz, B.

    2016-12-01

    As a consequence of their growing use in a range of electronic and industrial applications, increasing amounts of technology critical elements (TCEs) are being released to the environment. Currently, little is known about their fate and potential environmental impact. We report here on the adsorption of TCEs on sand and soil in the presence of selected nanoparticles (NPs). TCEs were tested within three different mixtures containing (i) rare earth elements (REEs), (ii) Ge, Pd, Ru and Ir together with Mo, Sb, Sn and Ti, and (iii) In, Sc, Th, Y and Yb together with a variety of other metals. The NPs examined for their suspending properties were: Al2O3, SiO2, CeO2, ZnO, Ag, Au, carbon dots and montmorillonite. Each NP was examined with each TCE solution mixture separately and with added humic acid. A clear difference was observed between REEs (and In, Sc), and the other TCEs. All REEs (and In, Sc) completely adsorb on soil and sand. For sand and soil, the presence of most NPs, alone, does not increase TCE concentrations in solution. For sand, addition of humic acid, with or without NPs, yields approximately the same increase in TCE concentration in solution (>80%). For soil solutions, presence of both NPs and humic acid increases TCE concentrations up to 500% more than any other combination tested, yielding 20% of added TCE amount. The other TCEs tested (mixtures (ii) and (iii)) adsorb less strongly to soil and sand, and unlike the REEs no general trend can be identified. For Al2O3, SiO2, CeO2, ZnO, carbon dots and montmorillonite, the increased concentrations of TCEs in the presence of NPs and humic acid were similar. This indicates that the observed effect depends on the presence of NPs and their surface coating rather than on the type of NP. Ag and Au NPs, however, reduce adsorption of TCEs to sand even when humic acid is absent. For example, Ag NPs reduce adsorption of REEs by >90% and Au NPs by 10%. For REEs, increased solution concentrations are correlated

  1. Plant extract: a promising biomatrix for ecofriendly, controlled synthesis of silver nanoparticles.

    PubMed

    Borase, Hemant P; Salunke, Bipinchandra K; Salunkhe, Rahul B; Patil, Chandrashekhar D; Hallsworth, John E; Kim, Beom S; Patil, Satish V

    2014-05-01

    Uses of plants extracts are found to be more advantageous over chemical, physical and microbial (bacterial, fungal, algal) methods for silver nanoparticles (AgNPs) synthesis. In phytonanosynthesis, biochemical diversity of plant extract, non-pathogenicity, low cost and flexibility in reaction parameters are accounted for high rate of AgNPs production with different shape, size and applications. At the same time, care has to be taken to select suitable phytofactory for AgNPs synthesis based on certain parameters such as easy availability, large-scale nanosynthesis potential and non-toxic nature of plant extract. This review focuses on synthesis of AgNPs with particular emphasis on biological synthesis using plant extracts. Some points have been given on selection of plant extract for AgNPs synthesis and case studies on AgNPs synthesis using different plant extracts. Reaction parameters contributing to higher yield of nanoparticles are presented here. Synthesis mechanisms and overview of present and future applications of plant-extract-synthesized AgNPs are also discussed here. Limitations associated with use of AgNPs are summarised in the present review.

  2. Amino acid mediated synthesis of silver nanoparticles and preparation of antimicrobial agar/silver nanoparticles composite films.

    PubMed

    Shankar, Shiv; Rhim, Jong-Whan

    2015-10-05

    Silver nanoparticles (AgNPs) were synthesized using amino acids (tyrosine and tryptophan) as reducing and capping agents, and they were incorporated into the agar to prepare antimicrobial composite films. The AgNPs solutions exhibited characteristic absorption peak at 420 nm that showed a red shift to ∼434 nm after forming composite with agar. XRD data demonstrated the crystalline structure of AgNPs with dominant (111) facet. Apparent surface color and transmittance of agar films were greatly influenced by the AgNPs. The incorporation of AgNPs into agar did not exhibit any change in chemical structure, thermal stability, moisture content, and water vapor permeability. The water contact angle, tensile strength, and modulus decreased slightly, but elongation at break increased after AgNPs incorporation. The agar/AgNPs nanocomposite films possessed strong antibacterial activity against Listeria monocytogenes and Escherichia coli. The agar/AgNPs film could be applied to the active food packaging by controlling the food-borne pathogens. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Synthesis and Characterization of BSA Conjugated Silver Nanoparticles (Ag/BSA Nanoparticles) and Evaluation of Biological Properties of Ag/BSA Nanoparticles and Ag/BSA Nanoparticles Loaded Poly(hydroxy butyrate valerate) PHBV Films

    NASA Astrophysics Data System (ADS)

    Ambaye, Almaz

    Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa are the etiological agents of several infectious diseases. Antibiotic resistance by these three microbes has emerged as a prevalent problem due in part to the misuse of existing antibiotics and the lack of novel antibiotics. Nanoparticles have emerged as an alternative antibacterial agents to conventional antibiotics owing to their high surface area to volume ratio and their unique chemical and physical properties. Among the nanoparticles, silver nanoparticles have gained increasing attention because silver nanoparticles exhibit antibacterial activity against a range of gram positive and gram negative bacteria. Nanoparticles of well-defined chemistry and morphology can be used in broad biomedical applications, especially in bone tissue engineering applications, where bone infection by bacteria can be acute and lethal. It is commonly noted in the literature that the activity of nanoparticles against microorganisms is dependent upon the size and concentration of the nanoparticles as well as the chemistry of stabilizing agent. To the best of our knowledge, a comprehensive study that evaluates the antibacterial activity of well characterized silver nanoparticles in particular Bovine Serum Albumin (BSA) stabilized against S. aureus and E. coli and cytotoxicity level of BSA stabilized silver nanoparticles towards osteoblast cells (MC3T3-E1) is currently lacking. Therefore, the primary objective of this study was to characterize protein conjugated silver nanoparticles prepared by chemical reduction of AgNO3 and BSA mixture. The formation of Ag/BSA nanoparticles was studied by UV-Vis spectroscopy. The molar ratio of silver to BSA in the Ag/BSA nanoparticles was established to be 27+/- 3: 1, based on Thermogravimetric Analysis and Atomic Absorption Spectroscopy. Based on atomic force microscopy, dynamic light scattering,and transmission electron microscopy(TEM) measurements, the particle size (diameter) of

  4. Fungi-assisted silver nanoparticle synthesis and their applications.

    PubMed

    Khan, Azhar U; Malik, Nazia; Khan, Masudulla; Cho, Moo Hwan; Khan, Mohammad Mansoob

    2018-01-01

    Nanotechnology is a rapidly developing field because of its wide range of applications in science, nanoscience and biotechnology. Nanobiotechnology deals with nanomaterials synthesised or modified using biotechnology. Fungi are used to synthesise metal nanoparticles and they have vast applications in wound healing, pathogen detection and control, food preservation, textiles, fabrics, etc. The present review describes the different types of fungi used for the biosyntheses of silver nanoparticles (AgNPs), along with their characterisation and possible biological applications. AgNPs synthesised by other physical and chemical methods are expensive and have toxic substances adsorbed onto them. Therefore, green, simple and effective approaches have been chosen for the biosynthesis of AgNPs, which are very important because of their lower toxicity and environmentally friendly behaviour. AgNPs synthesised using fungi have high monodispersity, specific composition and a narrow size range. In this regard, among the different biological methods used for metal nanoparticle synthesis, fungi are considered to be a superior biogenic method owing to their diversity and better size control. To further understand the biosynthesis of AgNPs using various fungi and evaluate their potential applications, this review discusses the antimicrobial, antibacterial, antifungal, antiviral, antidermatophytic, anti-inflammatory, antitumor, hepatoprotective, cytotoxic, hypotensive, and immunomodulatory activities of these AgNPs. The synthesis of AgNPs using fungi is a clean, green, inexpensive, eco-friendly, reliable, and safe method that can be used for a range of applications in real life for the benefit of human beings.

  5. Use of ZnO:Tb down-conversion phosphor for Ag nanoparticle plasmon absorption using a He-Cd ultraviolet laser.

    PubMed

    Abbass, A E; Swart, H C; Kroon, R E

    2016-09-01

    Although noble metal nanoparticles (NPs) have attracted some attention for potentially enhancing the luminescence of rare earth ions for phosphor lighting applications, the absorption of energy by NPs can also be beneficial in biological and polymer applications where local heating is desired, e.g. photothermal applications. Strong interaction between incident laser light and NPs occurs only when the laser wavelength matches the NP plasmon resonance. Although lasers with different wavelengths are available and the NP plasmon resonance can be tuned by changing its size and shape or the dielectric medium (host material), in this work, we consider exciting the plasmon resonance of Ag NPs indirectly with a He-Cd UV laser using the down-conversion properties of Tb(3+) ions in ZnO. The formation of Ag NPs was confirmed by X-ray diffraction, transmission electron microscopy and UV-vis diffuse reflectance measurements. Radiative energy transfer from the Tb(3+) ions to the Ag NPs resulted in quenching of the green luminescence of ZnO:Tb and was studied by means of spectral overlap and lifetime measurements. The use of a down-converting phosphor, possibly with other rare earth ions, to indirectly couple a laser to the plasmon resonance wavelength of metal NPs is therefore successfully demonstrated and adds to the flexibility of such systems. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  6. IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles

    PubMed Central

    Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

    2016-01-01

    Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles. PMID:27170532

  7. IgA response and protection following nasal vaccination of chickens with Newcastle disease virus DNA vaccine nanoencapsulated with Ag@SiO2 hollow nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Rong, Guangyu; Hao, Yan; Yu, Lu; Kang, Hong; Wang, Xin; Wang, Xiaohua; Jin, Zheng; Ren, Zhiyu; Li, Zejun

    2016-05-01

    Newcastle disease caused by ND virus (NDV) is a highly contagious disease of birds. Vaccine for effective protection of poultry animals from NDV infection is urgently needed. Mucosal immunity plays a very important role in the antiviral immune response. In this study, a NDV F gene-containing DNA vaccine encapsulated in Ag@SiO2 hollow nanoparticles (pFDNA-Ag@SiO2-NPs) with an average diameter of 500 nm were prepared to assess the mucosal immune response. These nanoparticles exhibited low cytotoxicity and did not destroy the bioactivity of plasmid DNA, which could be expressed in vitro. The plasmid DNA was sustainably released after an initial burst release. In vivo immunization showed that the intranasal immunization of chickens with pFDNA-Ag@SiO2-NPs induced high titers of serum antibody, significantly promoted lymphocyte proliferation and induced higher expression levels of IL-2 and IFN-γ in a dose-dependent manner. These results indicated that the Ag@SiO2 hollow nanoparticles could serve as an efficient and safe delivery carrier for NDV DNA vaccine to induce mucosal immunity. This study has provided promising results for the further development of mucosal vaccines encapsulated in inorganic nanoparticles.

  8. A green method to prepare Pd-Ag nanoparticles supported on reduced graphene oxide and their electrochemical catalysis of methanol and ethanol oxidation

    NASA Astrophysics Data System (ADS)

    Li, Lingzhi; Chen, Mingxi; Huang, Guanbo; Yang, Nian; Zhang, Li; Wang, Huan; Liu, Yu; Wang, Wei; Gao, Jianping

    2014-10-01

    Bimetallic palladium-silver nanoparticles (NPs) supported on reduced oxide graphene (RGO) with different Pd/Ag ratios (Pd-Ag/RGO) were prepared by an easy green method which did not use any additional reducing agents or a dispersing agent. During the process, simultaneous redox reactions between AgNO3, K2PdCl4 and graphene oxide (GO) led to bimetallic Pd-Ag NPs. The morphology and composition of the Pd-Ag/RGO were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis and Raman spectroscopy. Cyclic voltammetry and chronoamperometry were used to investigate the electrochemical activities and stabilities of these Pd-Ag/RGO catalysts for the electro-oxidation of methanol and ethanol in alkaline media. Among the different Pd/Ag ratios, the Pd-Ag (1:1)/RGO had the best catalytic activities and stability. So it is a promising catalyst for direct alcohol fuel cell applications.

  9. Genotoxicity of Silver Nanoparticles in Vicia faba: A Pilot Study on the Environmental Monitoring of Nanoparticles

    PubMed Central

    Patlolla, Anita K.; Berry, Ashley; May, LaBethani; Tchounwou, Paul B.

    2012-01-01

    The use of silver nanoparticles (AgNPs) in commercial products has increased significantly in recent years. Although there have been some attempts to determine the toxic effects of AgNPs in mammalian and human cell-lines, there is little information on plants which play a vital role in ecosystems. The study reports the use of Vicia faba root-tip meristem to investigate the genotoxicity of AgNPs under modified GENE-TOX test conditions. The root tip cells of V. faba were treated with four different concentrations of engineered AgNPs dispersion to study toxicological endpoints such as mitotic index (MI), chromosomal aberrations (CA) and micronucleus induction (MN). For each concentration, five sets of microscopy observations were carried out. The results demonstrated that AgNPs exposure significantly increased (p < 0.05) the number of chromosomal aberrations, micronuclei, and decreased the MI in exposed groups compared to control. From this study we infer that AgNPs might have penetrated the plant system and may have impaired mitosis causing CA and MN. The results of this study demonstrate that AgNPs are genotoxic to plant cells. Since plant assays have been integrated as a genotoxicity component in risk assessment for detection of environmental mutagens, they should be given full consideration when evaluating the overall toxicological impact of the nanoparticles in the environment. PMID:22754463

  10. Genotoxicity of silver nanoparticles in Vicia faba: a pilot study on the environmental monitoring of nanoparticles.

    PubMed

    Patlolla, Anita K; Berry, Ashley; May, LaBethani; Tchounwou, Paul B

    2012-05-01

    The use of silver nanoparticles (AgNPs) in commercial products has increased significantly in recent years. Although there have been some attempts to determine the toxic effects of AgNPs in mammalian and human cell-lines, there is little information on plants which play a vital role in ecosystems. The study reports the use of Vicia faba root-tip meristem to investigate the genotoxicity of AgNPs under modified GENE-TOX test conditions. The root tip cells of V. faba were treated with four different concentrations of engineered AgNPs dispersion to study toxicological endpoints such as mitotic index (MI), chromosomal aberrations (CA) and micronucleus induction (MN). For each concentration, five sets of microscopy observations were carried out. The results demonstrated that AgNPs exposure significantly increased (p < 0.05) the number of chromosomal aberrations, micronuclei, and decreased the MI in exposed groups compared to control. From this study we infer that AgNPs might have penetrated the plant system and may have impaired mitosis causing CA and MN. The results of this study demonstrate that AgNPs are genotoxic to plant cells. Since plant assays have been integrated as a genotoxicity component in risk assessment for detection of environmental mutagens, they should be given full consideration when evaluating the overall toxicological impact of the nanoparticles in the environment.

  11. Biofabrication of broad range antibacterial and antibiofilm silver nanoparticles.

    PubMed

    Qayyum, Shariq; Khan, Asad Ullah

    2016-10-01

    Silver nanoparticles (AgNPs) were biosynthesized via a green route using ten different plants extracts (GNP1- Caryota urens , GNP2- Pongamia glabra , GNP3- Hamelia patens , GNP4- Thevetia peruviana , GNP5- Calendula officinalis , GNP6- Tectona grandis , GNP7- Ficus petiolaris , GNP8- Ficus busking , GNP9- Juniper communis, GNP10- Bauhinia purpurea ). AgNPs were tested against drug resistant microbes and their biofilms. These nanoparticles (NPs) were characterised using UV-vis spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction and Image J software. Most of the AgNPs were distributed over a range of 1 of 60 nm size. The results indicated that AgNPs were antibacterial in nature without differentiating between resistant or susceptible strains. Moreover, the effect was more prominent on Gram negative bacteria then Gram positive bacteria and fungus. AgNPs inhibited various classes of microbes with different concentration. It was also evident from the results that the origin or nature of extract did not affect the activity of the NPs. Protein and carbohydrate leakage assays confirmed that the cells lysis is one of the main mechanisms for the killing of microbes by green AgNPs. This study suggests that the action of AgNPs on microbial cells resulted into cell lysis and DNA damage. Excellent microbial biofilm inhibition was also seen by these green AgNPs. AgNPs have proved their candidature as a potential antibacterial and antibiofilm agent against MDR microbes.

  12. Combined use of vancomycin-modified Ag-coated magnetic nanoparticles and secondary enhanced nanoparticles for rapid surface-enhanced Raman scattering detection of bacteria

    PubMed Central

    Pang, Yuanfeng; Xiao, Rui; Wang, Shengqi

    2018-01-01

    Background Pathogenic bacteria have always been a significant threat to human health. The detection of pathogens needs to be rapid, accurate, and convenient. Methods We present a sensitive surface-enhanced Raman scattering (SERS) biosensor based on the combination of vancomycin-modified Ag-coated magnetic nanoparticles (Fe3O4@Ag-Van MNPs) and Au@Ag nanoparticles (NPs) that can effectively capture and discriminate bacterial pathogens from solution. The high-performance Fe3O4@Ag MNPs were modified with vancomycin and used as bacteria capturer for magnetic separation and enrichment. The modified MNPS were found to exhibit strong affinity with a broad range of Gram-positive and Gram-negative bacteria. After separating and rinsing bacteria, Fe3O4@Ag-Van MNPs and Au@Ag NPs were synergistically used to construct a very large number of hot spots on bacteria cells, leading to ultrasensitive SERS detection. Results The dominant merits of our dual enhanced strategy included high bacterial-capture efficiency (>65%) within a wide pH range (pH 3.0–11.0), a short assay time (<30 min), and a low detection limit (5×102 cells/mL). Moreover, the spiked tests show that this method is still valid in milk and blood samples. Owing to these capabilities, the combined system enabled the sensitive and specific discrimination of different pathogens in complex solution, as verified by its detection of Gram-positive bacterium Escherichia coli, Gram-positive bacterium Staphylococcus aureus, and methicillin-resistant S. aureus. Conclusion This method has great potential for field applications in food safety, environmental monitoring, and infectious disease diagnosis. PMID:29520142

  13. Comparative toxicity of silver nanoparticles and silver ions to Escherichia coli.

    PubMed

    Choi, Yoojin; Kim, Hyun-A; Kim, Kyoung-Woong; Lee, Byung-Tae

    2018-04-01

    With the increase in silver (Ag)-based products in our lives, it is essential to test the potential toxicity of silver nanoparticles (AgNPs) and silver ions (Ag ions) on living organisms under various conditions. Here, we investigated the toxicity of AgNPs with Ag ions to Escherichia coli K-12 strain under various conditions. We observed that both AgNPs and Ag ions display antibacterial activities, and that Ag ions had higher toxicity to E. coli K-12 strain than AgNPs under the same concentrations. To understand the toxicity of AgNPs at a cellular level, reactive oxygen species (ROS) enzymes were detected for use as antioxidant enzymatic biomarkers. We have also studied the toxicity of AgNPs and Ag ions under various coexistence conditions including: fixed total concentration, with a varied the ratio of AgNPs to Ag ions; fixed the AgNPs concentration and then increased the Ag ions concentration; fixed Ag ions concentration and then increasing the AgNPs concentration. Exposure to AgNPs and Ag ions clearly had synergistic toxicity; however, decreased toxicity (for a fixed AgNPs concentration of 5mg/L, after increasing the Ag ions concentration) to E. coli K-12 strain. AgNPs and Ag ions in the presence of L-cysteine accelerated the bacterial cell growth rate, thereby reducing the bioavailability of Ag ions released from AgNPs under the single and coexistence conditions. Further works are needed to consider this potential for AgNPs and Ag ions toxicity across a range of environmental conditions. As silver nanoparticles (AgNPs)-based products are being broadly used in commercial industries, an ecotoxicological understanding of the AgNPs being released into the environment should be further considered. Here, we investigate the comparative toxicity of AgNPs and silver ions (Ag ions) to Escherichia coli K-12 strain, a representative ecotoxicological bioreporter. This study showed that toxicities of AgNPs and Ag ions to E. coli K-12 strain display different relationships

  14. Structural and optical properties of antimony-germanate-borate glass and glass fiber co-doped Eu3+ and Ag nanoparticles.

    PubMed

    Zmojda, Jacek; Kochanowicz, Marcin; Miluski, Piotr; Baranowska, Agata; Pisarski, Wojciech A; Pisarska, Joanna; Jadach, Renata; Sitarz, Maciej; Dorosz, Dominik

    2018-08-05

    In the paper analysis of structural and luminescent properties of antimony-germanate-borate glasses and glass fiber co-doped with 0.6AgNO 3 /0.2Eu 2 O 3 are presented. Heat treatment of the fabricated glass and optical fiber (400 °C, 12 h) enabled to obtain Ag nanoparticles (NPs) with average size 30-50 nm on their surface. It has been proofed that silver ions migrate to the glass surface, where they are reduced to Ag 0 nanoparticles. Simultaneously, FTIR analysis showed that heat treatment of the glass and optical fiber increases the local symmetry of the Eu 3+ site. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Environment friendly approach for size controllable synthesis of biocompatible Silver nanoparticles using diastase.

    PubMed

    Maddinedi, Sireesh Babu; Mandal, Badal Kumar; Anna, Kiran Kumar

    2017-01-01

    A green, facile method for the size selective synthesis of silver nanoparticles (AgNPs) using diastase as green reducing and stabilizing agent is reported. The thiol groups present in the diastase are mainly responsible for the rapid reaction rate of silver nanoparticles synthesis. The variation in the size and morphology of AgNPs were studied by changing the pH of diastase. The prepared silver nanoparticles were characterized by using UV-vis, XRD, FTIR, TEM and SAED. The FTIR analysis revealed the stabilization of diastase molecules on the surface of AgNPs. Additionally, in-vitro cytotoxicity experiments concluded that the cytotoxicity of the as-synthesized AgNPs towards mouse fibroblast (3T3) cell lines is dose and size dependent. Furthermore, the present method is an alternative to the traditional chemical methods of size controlled AgNPs synthesis. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Catalytic and antibacterial properties of silver nanoparticles green biosynthesized using soluble green tea powder

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Fan, Yapei; Liu, Xinfang; Luo, Denglin; Liu, Huan; Yang, Ningning

    2018-04-01

    Silver nanoparticles (Ag NPs) were green fabricated using soluble green tea powder (SGTP) as stabilizer and reducing agent. The properties and morphology of Ag NPs were investigated through UV–visible spectroscopy, field emission transmission electron microscope (FE-TEM) and fourier transform infrared (FT-IR). The spectroscopy showed surface plasmon resonance around at 420 nm revealing the synthesis of Ag NPs. FE-TEM results confirmed that the Ag NPs are spherical and face-centered cubic structure. FT-IR spectroscopy identified the role of various functional groups in the nanoparticle synthesis. The one spot biosynthesized Ag NPs showed favourable antibacterial properties on Escherichia coli and Staphyloccocus aureus, and excellent catalytic reduction of 4-nitrophenol. This work provided a feasible, green method to fabricate Ag NPs with promising photocatalytic and antimicrobial activities.

  17. The structural conversion from α-AgVO3 to β-AgVO3: Ag nanoparticle decorated nanowires with application as cathode materials for Li-ion batteries.

    PubMed

    McNulty, David; Ramasse, Quentin; O'Dwyer, Colm

    2016-09-15

    The majority of electrode materials in batteries and related electrochemical energy storage devices are fashioned into slurries via the addition of a conductive additive and a binder. However, aggregation of smaller diameter nanoparticles in current generation electrode compositions can result in non-homogeneous active materials. Inconsistent slurry formulation may lead to inconsistent electrical conductivity throughout the material, local variations in electrochemical response, and the overall cell performance. Here we demonstrate the hydrothermal preparation of Ag nanoparticle (NP) decorated α-AgVO 3 nanowires (NWs) and their conversion to tunnel structured β-AgVO 3 NWs by annealing to form a uniform blend of intercalation materials that are well connected electrically. The synthesis of nanostructures with chemically bound conductive nanoparticles is an elegant means to overcome the intrinsic issues associated with electrode slurry production, as wire-to-wire conductive pathways are formed within the overall electrode active mass of NWs. The conversion from α-AgVO 3 to β-AgVO 3 is explained in detail through a comprehensive structural characterization. Meticulous EELS analysis of β-AgVO 3 NWs offers insight into the true β-AgVO 3 structure and how the annealing process facilitates a higher surface coverage of Ag NPs directly from ionic Ag content within the α-AgVO 3 NWs. Variations in vanadium oxidation state across the surface of the nanowires indicate that the β-AgVO 3 NWs have a core-shell oxidation state structure, and that the vanadium oxidation state under the Ag NP confirms a chemically bound NP from reduction of diffused ionic silver from the α-AgVO 3 NWs core material. Electrochemical comparison of α-AgVO 3 and β-AgVO 3 NWs confirms that β-AgVO 3 offers improved electrochemical performance. An ex situ structural characterization of β-AgVO 3 NWs after the first galvanostatic discharge and charge offers new insight into the Li + reaction

  18. One-step preparation of antimicrobial silver nanoparticles in polymer matrix

    NASA Astrophysics Data System (ADS)

    Lyutakov, O.; Kalachyova, Y.; Solovyev, A.; Vytykacova, S.; Svanda, J.; Siegel, J.; Ulbrich, P.; Svorcik, V.

    2015-03-01

    Simple one-step procedure for in situ preparation of silver nanoparticles (AgNPs) in the polymer thin films is described. Nanoparticles (NPs) were prepared by reaction of N-methyl pyrrolidone with silver salt in semi-dry polymer film and characterized by transmission electron microscopy, XPS, and UV-Vis spectroscopy techniques. Direct synthesis of NPs in polymer has several advantages; even though it avoids time-consuming NPs mixing with polymer matrix, uniform silver distribution in polymethylmethacrylate (PMMA) films is achieved without necessity of additional stabilization. The influence of the silver concentration, reaction temperature and time on reaction conversion rate, and the size and size-distribution of the AgNPs was investigated. Polymer films doped with AgNPs were tested for their antibacterial activity on Gram-negative bacteria. Antimicrobial properties of AgNPs/PMMA films were found to be depended on NPs concentration, their size and distribution. Proposed one-step synthesis of functional polymer containing AgNPs is environmentally friendly, experimentally simple and extremely quick. It opens up new possibilities in development of antimicrobial coatings with medical and sanitation applications.

  19. Silver nanoparticles coated with natural polysaccharides as models to study AgNP aggregation kinetics using UV-Visible spectrophotometry upon discharge in complex environments.

    PubMed

    Lodeiro, Pablo; Achterberg, Eric P; Pampín, Joaquín; Affatati, Alice; El-Shahawi, Mohammed S

    2016-01-01

    This study provides quantitative information on the aggregation and dissolution behaviour of silver nanoparticles (AgNPs) upon discharge in fresh and sea waters, represented here as NaCl solutions of increasing ionic strength (up to 1M) and natural fjord waters. Natural polysaccharides, sodium alginate (ALG) and gum Arabic (GA), were used as coatings to stabilize the AgNPs and the compounds acted as models to study AgNP aggregation kinetics. The DLVO theory was used to quantitatively describe the interactions between the AgNPs. The stability of AgNPs was established using UV-Visible spectrophotometry, including unique information collected during the first seconds of the aggregaton process. Alginate coating resulted in a moderate stabilization of AgNPs in terms of critical coagulation concentration (~82mM NaCl) and a low dissolution of <10% total Ag in NaCl solutions up to 1M. Gum Arabic coated AgNPs were more strongly stabilized, with ~7-30% size increase up to 77mM NaCl, but only when the silver ion content initially present in solution was low (<10% total Ag). The ALG and GA coated AgNPs showed a strongly enhanced stability in natural fjord waters (ca. 5h required to reduce the area of the surface plasmon resonance band (SPRB) by two fold) compared with NaCl at an equivalent ionic strength (1-2min period for a two fold SPRB reduction). This is ascribed to a stabilizing effect from dissolved organic matter present in natural fjord waters. Interestingly, for AgNP-GA solutions with 40% of total silver present as unreacted silver ions in the NP stock solution, fast aggregation kinetics were observed in NaCl solutions (SPRB area was reduced by ca. 50% within 40-150min), with even more rapid removal in fjord waters, attributed to the high amount of silver-chloride charged species, that interact with the NP coating and/or organic matter and reduce the NPs stabilization. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Characterization and interplay of bacteriocin and exopolysaccharide-mediated silver nanoparticles as an antibacterial agent.

    PubMed

    Ansari, Asma; Pervez, Sidra; Javed, Urooj; Abro, Muhammad Ishaque; Nawaz, Muhammad Asif; Qader, Shah Ali Ul; Aman, Afsheen

    2018-04-22

    Metallic nanoparticles have a substantial scientific interest because of their distinctive physicochemical and antimicrobial properties and the emergence of multidrug resistant pathogens could unlock the potential of nanoparticles to combat infectious diseases. The aim of the current study is to enhance the antibacterial potential of purified bacteriocin by combining bacteriocin and antibacterial silver nanoparticles (AgNPs). Hence, the interaction of natural antimicrobial compounds and antibacterial nanoparticles can be used as a potential tool for combating infectious diseases. In this study, a green, simple and effective approach is used to synthesize antibacterial AgNPs using fungal exopolysaccharide as both a reducing and stabilizing agent. The AgNPs were characterized by spectroscopic analysis, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Dynamic Light Scattering (DLS). Furthermore, the synergistic effect of bacteriocin-AgNPs was determined against pathogenic strains. The histogram of AgNPs indicated well-dispersed, stabilized and negatively charged particles with variable size distribution. The combination of bacteriocin with nanoparticles found to be more effective due to broad antibacterial potential with possibly lower doses. The current study is imperative to provide an alternative for the chemical synthesis of silver nanoparticles. It showed environmental friendly and cost effective green synthesis of antibacterial nanoparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Use of carbon paste electrodes for the voltammetric detection of silver leached from the oxidative dissolution of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Mullaugh, Katherine M.; Pearce, Olivia M.

    2017-04-01

    The widespread use of silver nanoparticles (Ag NPs) in consumer goods has raised concerns about the release of silver in environmental waters. Of particular concern is the oxidative dissolution of Ag NPs to release Ag+ ions, which are highly toxic to many aquatic organisms. Here, we have investigated the application of differential pulse stripping voltammetry (DPSV) with carbon paste electrodes (CPEs) in monitoring the oxidation of Ag NPs. Using a commercially available, unmodified carbon paste and 60-s deposition times, a detection limit of 3 nM Ag+ could be achieved. We demonstrate its selectivity for free Ag+ ions over Ag nanoparticles, allowing for analysis of the oxidation of Ag NPs without the need for separation of ions and nanoparticles prior to analysis. We applied this approach to investigate the effect of pH in the oxidative dissolution of Ag NPs, demonstrating the usefulness of CPEs in studies of this type.

  2. Third-order optical nonlinearity studies of bilayer Au/Ag metallic films

    NASA Astrophysics Data System (ADS)

    Mezher, M. H.; Chong, W. Y.; Zakaria, R.

    2016-05-01

    This paper presents nonlinear optical studies of bilayer metallic films of gold (Au) and silver (Ag) on glass substrate prepared using electron beam evaporation. The preparation of Au and Ag nanoparticles (NPs) on the substrate involved the use of electron beam deposition, then thermal annealing at 600 °C and 270 °C, respectively, to produce a randomly distributed layer of Au and a layer of Ag NPs. Observation of field-effect scanning electron microscope images indicated the size of the NPs. Details of the optical properties related to peak absorption of surface plasmon resonance of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear absorption and nonlinear refraction of the fabricated NP layers. The third-order nonlinear refractive index coefficients for Au and Ag are (-9.34 and  -1.61)  ×  10-11 cm2 W-1 given lower n 2, in comparison with bilayer (Au and Ag) NPs at  -1.24  ×  10-10 cm2 W-1. The results show bilayer NPs have higher refractive index coefficients thus enhance the nonlinearity effects.

  3. The cellular responses and antibacterial activities of silver nanoparticles stabilized by different polymers

    NASA Astrophysics Data System (ADS)

    Lin, Jiang-Jen; Lin, Wen-Chun; Dong, Rui-Xuan; Hsu, Shan-hui

    2012-02-01

    Silver nanoparticles (AgNPs) are known for their excellent antibacterial activities. The possible toxicity, however, is a major concern for their applications. Three types of AgNPs were prepared in this study by chemical processes. Each was stabilized by a polymer surfactant, which was expected to reduce the exposure of cells to AgNPs and therefore their cytotoxicity. The polymer stabilizers included poly(oxyethylene)-segmented imide (POEM), poly(styrene-co-maleic anhydride)-grafting poly(oxyalkylene) (SMA) and poly(vinyl alcohol) (PVA). The cytotoxicity of these chemically produced AgNPs to mouse skin fibroblasts (L929), human hepatocarcinoma cells (HepG2), and mouse monocyte macrophages (J774A1) was compared to that of physically produced AgNPs and gold nanoparticles (AuNPs) as well as the standard reference material RM8011 AuNPs. Results showed that SMA-AgNPs were the least cytotoxic among all materials, but cytotoxicity was still observed at higher silver concentrations (>30 ppm). Macrophages demonstrated the inflammatory response with cell size increase and viability decrease upon exposure to 10 ppm of the chemically produced AgNPs. SMA-AgNPs did not induce hemolysis at a silver concentration below 1.5 ppm. Regarding the antibacterial activity, POEM-AgNPs and SMA-AgNPs at 1 ppm silver content showed 99.9% and 99.3% growth inhibition against E. coli, while PVA-AgNPs at the same silver concentration displayed 79.1% inhibition. Overall, SMA-AgNPs demonstrated better safety in vitro and greater antibacterial effects than POEM-AgNPs and PVA-AgNPs. This study suggested that polymer stabilizers may play an important role in determining the toxicity of AgNPs.

  4. In-vitro free radical scavenging activity of biosynthesized gold and silver nanoparticles using Prunus armeniaca (apricot) fruit extract

    NASA Astrophysics Data System (ADS)

    Dauthal, Preeti; Mukhopadhyay, Mausumi

    2013-01-01

    In-vitro free radical scavenging activity of biosynthesized gold (Au-NPs) and silver (Ag-NPs) nanoparticles was investigated in the present study. Natural precursor Prunus armeniaca (apricot) fruit extract was used as a reducing agent for the nanoparticle synthesis. The free radical scavenging activity of the nanoparticles were observed by modified 1,1'-diphynyl-2-picrylhydrazyl, DPPH and 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS assay. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy, and fourier transform infrared spectroscopy (FTIR). Appearance of optical absorption peak at 537 nm (2.20 keV) and 435 nm (3 keV) within 0.08 and 0.5 h of reaction time was confirmed the presence of metallic Au and Ag nanoclusters, respectively. Nearly spherical nanoparticles with majority of particle below 20 nm (TEM) for both Au-NPs and Ag-NPs were synthesized. XRD pattern confirmed the existence of pure nanocrystalline Au-NPs while few additional peaks in the vicinity of fcc silver-speculated crystallization of metalloproteins of fruit extract on the surface of the Ag-NPs and vice versa. FTIR spectra was supported the role of amino acids of protein/enzymes of fruit extract for synthesis and stabilization of nanoparticles. Dose-dependent scavenging activity was observed for Au-NPs and Ag-NPs in both DPPH and ABTS in-vitro assay. 50 % scavenging activity for DPPH were 11.27 and 16.18 mg and for ABTS 3.40 and 7.12 mg with Au-NPs and Ag-NPs, respectively.

  5. Studying the morphological features of plasma treated silver and PEGylated silver nanoparticles: antibacterial activity

    NASA Astrophysics Data System (ADS)

    Waseem, M.; Awan, T.; Yasin, H. M.; Rehman, N. U.

    2018-03-01

    A strategy to treat the silver and PEGylated silver nanoparticles with plasma was being purposed. Oil in water (o/w) microemulsion method was used for the synthesis of Ag nanoparticles (AgNPs). Polyethylene glycol (PEG) having molecular weight 600 was used to coat the surface of AgNPs. Optical emission spectroscopy (OES) was used to characterize the plasma and it is noted that plasma treatment is useful to modify the structural characteristic of silver nanoparticles. The nanoparticles were treated with helium-oxygen mixture plasma, generated in plasma needle at atmospheric pressure. Both AgNPs and PEGylated AgNPs before and after plasma treatment were characterized by x-rays diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The crystallite size of silver nanoparticles after the treatment of plasma decreases from 71 nm to 27 nm. The SEM micrographs show that the size of Ag nanoparticles was nearly 118 nm whereas the thickness of the silver needle was around 135 nm. All the characteristics IR bands associated to the silver nanoparticles were detected. The FTIR spectrum also support the accumulation of OH radicals in the plasma treated samples. The samples before and after plasma treatment were screened against Gram positive (Bacillus Subtilis and Staphylococcus Aureus) and Gram negative (Escherichia Coli and Pseudomonas Aeruginosa) bacteria. The promising response was detected when plasma treated PEGylated AgNPs was tested against bacterial strains.

  6. Natural inorganic nanoparticles--formation, fate, and toxicity in the environment.

    PubMed

    Sharma, Virender K; Filip, Jan; Zboril, Radek; Varma, Rajender S

    2015-12-07

    The synthesis, stability, and toxicity of engineered metal nanoparticles (ENPs) have been extensively studied during the past two decades. In contrast, research on the formation, fate, and ecological effects of naturally-occurring nanoparticles (NNPs) has become a focus of attention only recently. The natural existence of metal nanoparticles and their oxides/sulfides in waters, wastewaters, ore deposits, mining regions, and hydrothermal vents, as exemplified by the formation of nanoparticles containing silver and gold (AgNPs and AuNPs), Fe, Mn, pyrite (FeS2), Ag2S, CuS, CdS, and ZnS, is dictated largely by environmental conditions (temperature, pH, oxic/anoxic, light, and concentration and characteristics of natural organic matter (NOM)). Examples include the formation of nanoparticles containing pyrite, Cu and Zn-containing pyrite, and iron in hydrothermal vent black smoker emissions. Metal sulfide nanoparticles can be formed directly from their precursor ions or indirectly by sulfide ion-assisted transformation of the corresponding metal oxides under anaerobic conditions. This tutorial focuses on the formation mechanisms, fate, and toxicity of natural metal nanoparticles. Natural waters containing Ag(I) and Au(III) ions in the presence of NOM generate AgNPs and AuNPs under thermal, non-thermal, and photochemical conditions. These processes are significantly accelerated by existing redox species of iron (Fe(II)/Fe(III)). NOM, metal-NOM complexes, and reactive oxygen species (ROS) such as O2˙(-), ˙OH, and H2O2 are largely responsible for the natural occurrence of nanoparticles. AgNPs and AuNPs emanating from Ag(I)/Au(III)-NOM reactions are stable for several months, thus indicating their potential to be transported over long distances from their point of origin. However, endogenous cations present in natural waters can destabilize the nanoparticles, with divalent cations (e.g., Ca(2+), Mg(2+)) being more influential than their monovalent equivalents (e.g., Na

  7. C. elegans-on-a-chip for in situ and in vivo Ag nanoparticles’ uptake and toxicity assay

    NASA Astrophysics Data System (ADS)

    Kim, Jin Ho; Lee, Seung Hwan; Cha, Yun Jeong; Hong, Sung Jin; Chung, Sang Kug; Park, Tai Hyun; Choi, Shin Sik

    2017-01-01

    Nanomaterials are extensively used in consumer products and medical applications, but little is known about their environmental and biological toxicities. Moreover, the toxicity analysis requires sophisticated instruments and labor-intensive experiments. Here we report a microfluidic chip incorporated with the nematode Caenorhabditis elegans that rapidly displays the changes in body growth and gene expression specifically responsive to the silver nanoparticles (AgNPs). C. elegans were cultured in microfluidic chambers in the presence or absence of AgNPs and were consequently transferred to wedge-shaped channels, which immobilized the animals, allowing the evaluation of parameters such as length, moving distance, and fluorescence from the reporter gene. The AgNPs reduced the length of C. elegans body, which was easily identified in the channel of chip. In addition, the decrease of body width enabled the worm to advance the longer distance compared to the animal without nanoparticles in a wedge-shaped channel. The transgenic marker DNA, mtl-2::gfp was highly expressed upon the uptake of AgNPs, resulting in green fluorescence emission. The comparative investigation using gold nanoparticles and heavy-metal ions indicated that these parameters are specific to AgNPs. These results demonstrate that C. elegans-on-a-chip has a great potential as a rapid and specific nanoparticle detection or nanotoxicity assessment system.

  8. Generation of metal nanoparticles from silver and copper objects: nanoparticle dynamics on surfaces and potential sources of nanoparticles in the environment.

    PubMed

    Glover, Richard D; Miller, John M; Hutchison, James E

    2011-11-22

    The use of silver nanoparticles (AgNPs) in antimicrobial applications, including a wide range of consumer goods and apparel, has attracted attention because of the unknown health and environmental risks associated with these emerging materials. Of particular concern is whether there are new risks that are a direct consequence of their nanoscale size. Identifying those risks associated with nanoscale structure has been difficult due to the fundamental challenge of detecting and monitoring nanoparticles in products or the environment. Here, we introduce a new strategy to directly monitor nanoparticles and their transformations under a variety of environmental conditions. These studies reveal unprecedented dynamic behavior of AgNPs on surfaces. Most notably, under ambient conditions at relative humidities greater than 50%, new silver nanoparticles form in the vicinity of the parent particles. This humidity-dependent formation of new particles was broadly observed for a variety of AgNPs and substrate surface coatings. We hypothesize that nanoparticle production occurs through a process involving three stages: (i) oxidation and dissolution of silver from the surface of the particle, (ii) diffusion of silver ion across the surface in an adsorbed water layer, and (iii) formation of new, smaller particles by chemical and/or photoreduction. Guided by these findings, we investigated non-nanoscale sources of silver such as wire, jewelry, and eating utensils that are placed in contact with surfaces and found that they also formed new nanoparticles. Copper objects display similar reactivity, suggesting that this phenomenon may be more general. These findings challenge conventional thinking about nanoparticle reactivity and imply that the production of new nanoparticles is an intrinsic property of the material that is not strongly size dependent. The discovery that AgNPs and CuNPs are generated spontaneously from manmade objects implies that humans have long been in direct

  9. Towards Environmentally-benign Nanoengineering: Antimicrobial Nanoparticles Based on Silver-infused Lignin Cores

    NASA Astrophysics Data System (ADS)

    Richter, Alexander Philipp

    Engineered nanomaterials are capable of solving challenges in industries important to society such as energy, agriculture, and health care. Antimicrobial silver nanoparticles (AgNPs) are the most widely used nanoparticles by number of commercial products in commerce today. However, the increased introduction of AgNPs in industrial applications may lead to discharge of persistent nanoparticles in the environment and undesired impacts on living organisms. This dissertation will present a new class of antimicrobial environmentallybenign nanoparticles (EbNPs) designed with green chemistry principles, which can serve as highly efficient microbicide substitutes of the AgNPs. The EbNP core is made of biodegradable lignin, and is infused with an optimal amount of silver ions. We report on the fabrication of environmentally benign nanoparticles (EbNPs) using two types of lignin precursors with simple, inexpensive, and non-toxic processes, (i) by employing a solvent exchange precipitation method at room temperature and (ii) by applying an environmentally friendly water-based acid precipitation method. The synthesis of Organosolv (High Purity Lignin) nanoparticles via antisolvent flash precipitation method in water resulted in particles in the size range of 45 to 250 nm in diameter. We investigate the synthesis parameters of Kraft (Indulin AT) lignin nanoparticles by flash precipitation induced by pH drop in ethylene glycol. Furthermore, we evaluate the ionic strength and pH stability of both lignin nanoparticle suspensions and highlight differences in the systems. After silver ion infusion of Indulin AT nanoparticles followed by surface modification, we show that the EbNPs exhibit higher antimicrobial activity towards Gram-negative human pathogens Escherichia coli and Pseudomonas aeruginosa and Gram-positive human pathogens Staphylococcus epidermidis in direct comparison with silver nanoparticles and silver nitrate solution, and that the particles are effective against

  10. One pot light assisted green synthesis, storage and antimicrobial activity of dextran stabilized silver nanoparticles.

    PubMed

    Hussain, Muhammad Ajaz; Shah, Abdullah; Jantan, Ibrahim; Tahir, Muhammad Nawaz; Shah, Muhammad Raza; Ahmed, Riaz; Bukhari, Syed Nasir Abbas

    2014-12-03

    Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. Herein, we report green synthesis of silver nanoparticles (Ag NPs) mediated with dextran. Dextran was used as a stabilizer and capping agent to synthesize Ag NPs using silver nitrate (AgNO3) under diffused sunlight conditions. UV-vis spectra of as synthesized Ag nanoparticles showed characteristic surface plasmon band in the range from ~405-452 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies showed spherical Ag NPs in the size regime of ~50-70 nm. Face centered cubic lattice of Ag NPs was confirmed by powder X-ray diffraction (PXRD). FT-IR spectroscopy confirmed that dextran not only acts as reducing agent but also functionalizes the surfaces of Ag NPs to make very stable dispersions. Moreover, on drying, the solution of dextran stabilized Ag NPs resulted in the formation of thin films which were found stable over months with no change in the plasmon band of pristine Ag NPs. The antimicrobial assay of the as synthesized Ag NPs showed remarkable activity. Being significantly active against microbes, the Ag NPs can be explored for antimicrobial medical devices.

  11. A facile route to synthesize nanogels doped with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Coll Ferrer, M. Carme; Ferrier, Robert C.; Eckmann, David M.; Composto, Russell J.

    2013-01-01

    In this study, we describe a simple method to prepare hybrid nanogels consisting of a biocompatible core-shell polymer host containing silver nanoparticles. First, the nanogels (NG, 160 nm) containing a lysozyme rich core and a dextran rich shell, are prepared via Maillard and heat-gelation reactions. Second, silver nanoparticles (Ag NPs, 5 nm) are synthesized "in situ" in the NG solution without requiring additional reducing agents. This approach leads to stable Ag NPs located in the NG. Furthermore, we demonstrate that the amount of Ag NPs in the NG can be tuned by varying silver precursor concentration. Hybrid nanogels with silver nanoparticles have potential in antimicrobial, optical, and therapeutic applications.

  12. Silver Nanoparticles Induce HePG-2 Cells Apoptosis Through ROS-Mediated Signaling Pathways

    NASA Astrophysics Data System (ADS)

    Zhu, Bing; Li, Yinghua; Lin, Zhengfang; Zhao, Mingqi; Xu, Tiantian; Wang, Changbing; Deng, Ning

    2016-04-01

    Recently, silver nanoparticles (AgNPs) have been shown to provide a novel approach to overcome tumors, especially those of hepatocarcinoma. However, the anticancer mechanism of silver nanoparticles is unclear. Thus, the purpose of this study was to estimate the effect of AgNPs on proliferation and activation of ROS-mediated signaling pathway on human hepatocellular carcinoma HePG-2 cells. A simple chemical method for preparing AgNPs with superior anticancer activity has been showed in this study. AgNPs were detected by transmission electronic microscopy (TEM) and energy dispersive X-ray (EDX). The size distribution and zeta potential of silver nanoparticles were detected by Zetasizer Nano. The average size of AgNPs (2 nm) observably increased the cellular uptake by endocytosis. AgNPs markedly inhibited the proliferation of HePG-2 cells through induction of apoptosis with caspase-3 activation and PARP cleavage. AgNPs with dose-dependent manner significantly increased the apoptotic cell population (sub-G1). Furthermore, AgNP-induced apoptosis was found dependent on the overproduction of reactive oxygen species (ROS) and affecting of MAPKs and AKT signaling and DNA damage-mediated p53 phosphorylation to advance HePG-2 cells apoptosis. Therefore, our results show that the mechanism of ROS-mediated signaling pathways may provide useful information in AgNP-induced HePG-2 cell apoptosis.

  13. Silver nanoparticle induced cytotoxicity, oxidative stress, and DNA damage in CHO cells

    NASA Astrophysics Data System (ADS)

    Awasthi, Kumud Kant; Awasthi, Anjali; Kumar, Narender; Roy, Partha; Awasthi, Kamlendra; John, P. J.

    2013-09-01

    Silver nanoparticles (Ag NPs) are being used increasingly in wound dressings, catheters, and in various household products due to their antimicrobial activity. The present study reports the toxicity evaluation of synthesized and well characterized Ag NPs using Chinese hamster ovary (CHO) cells. The UV-Vis spectroscopy reveals the formation of silver nanoparticles by exhibiting the typical surface plasmon absorption maxima at 408-410 nm. Transmission electron microscopy (TEM) reveals that the average diameter of silver nanoparticles is about 5.0 ± 1.0 nm and that they have spherical shape. Cell visibility and cell viability percentage show dose-dependent cellular toxicity of Ag NPs. The half maximal inhibitory concentration (IC50) for CHO cells is 68.0 ± 2.65 μg/ml after 24 h Ag NPs exposure. Toxicity evaluations, including cellular morphology, mitochondrial function (MTT assay), reactive oxygen species (ROS), and DNA fragmentation assay (Ladder pattern) were assessed in unexposed CHO cells (control) and the cells exposed to Ag NPs concentrations of 15, 30, and 60 μg/ml for 24 h. The findings may assist in the designing of Ag NPs for various applications and provide insights into their toxicity.

  14. Developmental toxicity of Japanese medaka embryos by silver nanoparticles and released ions in the presence of humic acid.

    PubMed

    Kim, Jun Y; Kim, Ki-Tae; Lee, Byeong G; Lim, Byung J; Kim, Sang D

    2013-06-01

    The final destination point of nanoparticles is the environment, where they remain a long period; therefore, a deep understanding of the relationship between nanoparticles and the environmental factors is required. Japanese medaka embryos were exposed to two differently prepared AgNPs: freshly prepared AgNPs and aged AgNPs. With these two AgNP preparations, we studied the impacts of humic acid in terms of embryonic toxicity, as well as the behavior of AgNPs. Aged AgNPs exhibited a lower lethal concentration (LC50) value (1.44mg/L) compared to fresh AgNPs (3.53mg/L) through 96h acute toxicity tests, due to the release of silver ions, as confirmed by kinetic analysis. The presence of humic acids considerably reduced the toxicity of aged AgNPs due to complexation with silver ions. Agglomeration, induced by interactions with humic acid, might reduce the bioavailability of AgNPs to Japanese medaka embryos. This study demonstrates that aged AgNPs releasing more silver ions are more toxic than fresh AgNPs, and humic acids play a role in reducing the toxicity of aged AgNPs. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Lawsonia inermis-mediated synthesis of silver nanoparticles: activity against human pathogenic fungi and bacteria with special reference to formulation of an antimicrobial nanogel.

    PubMed

    Gupta, Arpita; Bonde, Shital R; Gaikwad, Swapnil; Ingle, Avinash; Gade, Aniket K; Rai, Mahendra

    2014-09-01

    Lawsonia inermis mediated synthesis of silver nanoparticles (Ag-NPs) and its efficacy against Candida albicans, Microsporum canis, Propioniabacterium acne and Trichophyton mentagrophytes is reported. A two-step mechanism has been proposed for bioreduction and formation of an intermediate complex leading to the synthesis of capped nanoparticles was developed. In addition, antimicrobial gel for M. canis and T. mentagrophytes was also formulated. Ag-NPs were synthesized by challenging the leaft extract of L. inermis with 1 mM AgNO₃. The Ag-NPs were characterized by Ultraviolet-Visible (UV-Vis) spectrophotometer and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM), nanoparticle tracking and analysis sytem (NTA) and zeta potential was measured to detect the size of Ag-NPs. The antimicrobial activity of Ag-NPs was evaluated by disc diffusion method against the test organisms. Thus these Ag-NPs may prove as a better candidate drug due to their biogenic nature. Moreover, Ag-NPs may be an answer to the drug-resistant microorganisms.

  16. Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles.

    PubMed

    Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

    2018-06-22

    Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

  17. Highly sensitive wearable strain sensor based on silver nanowires and nanoparticles

    NASA Astrophysics Data System (ADS)

    Shengbo, Sang; Lihua, Liu; Aoqun, Jian; Qianqian, Duan; Jianlong, Ji; Qiang, Zhang; Wendong, Zhang

    2018-06-01

    Here, we propose a highly sensitive and stretchable strain sensor based on silver nanoparticles and nanowires (Ag NPs and NWs), advancing the rapid development of electronic skin. To improve the sensitivity of strain sensors based on silver nanowires (Ag NWs), Ag NPs and NWs were added to polydimethylsiloxane (PDMS) as an aid filler. Silver nanoparticles (Ag NPs) increase the conductive paths for electrons, leading to the low resistance of the resulting sensor (14.9 Ω). The strain sensor based on Ag NPs and NWs showed strong piezoresistivity with a tunable gauge factor (GF) at 3766, and a change in resistance as the strain linearly increased from 0% to 28.1%. The high GF demonstrates the irreplaceable role of Ag NPs in the sensor. Moreover, the applicability of our high-performance strain sensor has been demonstrated by its ability to sense movements caused by human talking, finger bending, wrist raising and walking.

  18. 'Chocolate' silver nanoparticles: Synthesis, antibacterial activity and cytotoxicity.

    PubMed

    Chowdhury, Neelika Roy; MacGregor-Ramiasa, Melanie; Zilm, Peter; Majewski, Peter; Vasilev, Krasimir

    2016-11-15

    Silver nanoparticles (AgNPs) have emerged as a powerful weapon against antibiotic resistant microorganisms. However, most conventional AgNPs syntheses require the use of hazardous chemicals and generate toxic organic waste. Hence, in recent year's, plant derived and biomolecule based synthetics have has gained much attention. Cacao has been used for years for its medicinal benefits and contains a powerful reducing agent - oxalic acid. We hypothesized that, due to the presence of oxalic acid, cacao extract is capable of reducing silver nitrate (AgNO3) to produce AgNPs. In this study, AgNPs were synthesized by using natural cacao extract as a reducing and stabilizing agent. The reaction temperature, time and reactant molarity were varied to optimize the synthesis yield. UV-visible spectroscopy (UV-vis), dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization demonstrated that the synthesized AgNPs were spherical particles ranging in size from 35 to 42.5nm. The synthesized AgNPs showed significant antibacterial activity against clinically relevant pathogens such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis. Importantly, these green AgNPs are not cytotoxic to human dermal fibroblasts (HDFs) at concentrations below 32μg/ml. We conclude that cacao-based synthesis is a reproducible and sustainable method for the generation of stable antimicrobial silver nanoparticles with low cytotoxicity to human cells. The AgNPs synthesized in this work have promising properties for applications in the biomedical field. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Biosynthesis of silver nanoparticles using Alternanthera sessilis (Linn.) extract and their antimicrobial, antioxidant activities.

    PubMed

    Niraimathi, K L; Sudha, V; Lavanya, R; Brindha, P

    2013-02-01

    The present work focuses the use of the aqueous extract of Alternanthera sessilis Linn. (Amaranthaceae) in producing silver nanoparticles (AgNPs) from silver nitrate aqueous. Phytochemical analysis of the extract revealed the presence of alkaloid, tannins, ascorbic acid, carbohydrates and proteins and they serve as effective reducing and capping agents for converting silver nitrate into nanoparticles. The synthesized silver nanoparticles (AgNPs) were also tested for proteins and ascorbic acid. Its pH was also determined (5.63). The AgNPs obtained was characterized by UV-vis spectroscopy, FT-IR spectroscopy, SEM, Zeta sizer and TG-DSC. SEM images which revealed the presence of various shapes and sizes. FT-IR spectrum showed the AgNPs having a coating of proteins indicating a dual role of bio-molecules responsible for capping and efficient stabilization of the silver nanoparticles. Presence of impurities and melting point profile were screened by TG-DSC analyzer. AgNPs were synthesized from the silver nitrate through the reducing power of ascorbic acid present in A. sessilis leaves. In this study, we also investigated antimicrobial and antioxidant activity of green synthesized AgNPs. The antimicrobial activity is investigated by Bauer et al.'s method. Antioxidant activity was done by DPPH method. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Asymmetric dumbbell-shaped silver nanoparticles and spherical gold nanoparticles green-synthesized by mangosteen (Garcinia mangostana) pericarp waste extracts

    PubMed Central

    Park, Ji Su; Ahn, Eun-Young; Park, Youmie

    2017-01-01

    Mangosteen (Garcinia mangostana) pericarp waste extract was used to synthesize gold and silver nanoparticles by a green strategy. The extract was both a reducing and stabilizing agent during synthesis. Phytochemical screening of the extract was conducted to obtain information regarding the presence/absence of primary and secondary metabolites in the extract. The in vitro antioxidant activity results demonstrated that the extract had excellent antioxidant activity, which was comparable to a standard (butylated hydroxy toluene). Spherical gold nanoparticles (gold nanoparticles green synthesized by mangosteen pericarp extract [GM-AuNPs]) with an average size of 15.37±3.99 to 44.20±16.99 nm were observed in high-resolution transmission electron microscopy (HR-TEM) images. Most interestingly, the silver nanoparticles (silver nanoparticles green synthesized by mangosteen pericarp extract [GM-AgNPs]) had asymmetric nanodumbbell shapes where one tail grew from a spherical head. The average head size was measured to be 13.65±5.07 to 31.08±3.99 nm from HR-TEM images. The hydrodynamic size of both nanoparticles tended to increase with increasing extract concentration. Large negative zeta potentials (−18.92 to −34.77 mV) suggested that each nanoparticle solution possessed excellent colloidal stability. The reaction yields were 99.7% for GM-AuNPs and 82.8% for GM-AgNPs, which were assessed by inductively coupled plasma optical emission spectroscopy. A high-resolution X-ray diffraction pattern confirmed the face-centered cubic structure of both nanoparticles. Based on phytochemical screening and Fourier transform infrared spectra, the hydroxyl functional groups of carbohydrates, flavonoids, glycosides, and phenolic compounds were most likely involved in a reduction reaction of gold or silver salts to their corresponding nanoparticles. The in vitro cytotoxicity (based on a water-soluble tetrazolium assay) demonstrated that GM-AgNPs were toxic to both A549 (a human lung

  1. Asymmetric dumbbell-shaped silver nanoparticles and spherical gold nanoparticles green-synthesized by mangosteen (Garcinia mangostana) pericarp waste extracts.

    PubMed

    Park, Ji Su; Ahn, Eun-Young; Park, Youmie

    2017-01-01

    Mangosteen ( Garcinia mangostana ) pericarp waste extract was used to synthesize gold and silver nanoparticles by a green strategy. The extract was both a reducing and stabilizing agent during synthesis. Phytochemical screening of the extract was conducted to obtain information regarding the presence/absence of primary and secondary metabolites in the extract. The in vitro antioxidant activity results demonstrated that the extract had excellent antioxidant activity, which was comparable to a standard (butylated hydroxy toluene). Spherical gold nanoparticles (gold nanoparticles green synthesized by mangosteen pericarp extract [GM-AuNPs]) with an average size of 15.37±3.99 to 44.20±16.99 nm were observed in high-resolution transmission electron microscopy (HR-TEM) images. Most interestingly, the silver nanoparticles (silver nanoparticles green synthesized by mangosteen pericarp extract [GM-AgNPs]) had asymmetric nanodumbbell shapes where one tail grew from a spherical head. The average head size was measured to be 13.65±5.07 to 31.08±3.99 nm from HR-TEM images. The hydrodynamic size of both nanoparticles tended to increase with increasing extract concentration. Large negative zeta potentials (-18.92 to -34.77 mV) suggested that each nanoparticle solution possessed excellent colloidal stability. The reaction yields were 99.7% for GM-AuNPs and 82.8% for GM-AgNPs, which were assessed by inductively coupled plasma optical emission spectroscopy. A high-resolution X-ray diffraction pattern confirmed the face-centered cubic structure of both nanoparticles. Based on phytochemical screening and Fourier transform infrared spectra, the hydroxyl functional groups of carbohydrates, flavonoids, glycosides, and phenolic compounds were most likely involved in a reduction reaction of gold or silver salts to their corresponding nanoparticles. The in vitro cytotoxicity (based on a water-soluble tetrazolium assay) demonstrated that GM-AgNPs were toxic to both A549 (a human lung

  2. Synthesis and characterization of silver nanoparticles using Cynodon dactylon leaves and assessment of their antibacterial activity.

    PubMed

    Sahu, Nidhi; Soni, Deepika; Chandrashekhar, B; Sarangi, Bijaya Ketan; Satpute, Devanand; Pandey, Ram Avatar

    2013-07-01

    Many methods of synthesizing silver nanoparticles (Ag-NPs) by reducing Ag⁺ ions using aqueous/organic extracts of various plants have been reported in the past, but the methods are rather slow. In this investigation, silver nanoparticles were quickly synthesized from aqueous silver nitrate through a simple method using leaf extract of a plant--Cynodon dactylon which served as reducing agent, while sunlight acted as a catalyst. The formation of Ag-NPs was indicated by gradual change in colour and pH and confirmed by ultraviolet--visible spectroscopy. The Ag-NPs showed a surface plasmon resonance at 451 nm. Based on the decrease in pH, a possible mechanism of the synthesis of Ag-NPs involving hydroxyl (OH⁻) ions of polyphenols of the leaf extract is postulated. Ag-NPs having (111) and (200) crystal lattices were confirmed by X-ray diffraction. Scanning electron microscopy revealed the spherical nature of the Ag-NPs, while transmission electron microscopy showed that the nanoparticles were polydispersed with a size range of 8-10 nm. The synthesized Ag-NPs also demonstrated their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella typhimurium.

  3. Green synthesis, characterization and evaluation of biocompatibility of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahamed, Maqusood; Majeed Khan, M. A.; Siddiqui, M. K. J.; AlSalhi, Mohamad S.; Alrokayan, Salman A.

    2011-04-01

    Although green synthesis of silver nanoparticles (Ag NPs) by various plants and microorganisms has been reported, the potential of plants as biological materials for the synthesis of nanoparticles and their compatibility to biological systems is yet to be fully explored. In this study, we report a simple green method for the synthesis of Ag NPs using garlic clove extract as a reducing and stabilizing agent. In addition to green synthesis, biological response of Ag NPs in human lung epithelial A549 cells was also assessed. Ag NPs were rapidly synthesized using garlic clove extract and the formation of nanoparticles was observed within 30 min. The green synthesized Ag NPs were characterized using UV-vis spectrum, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X-ray energy-dispersive spectroscopy (EDX) and dynamic light scattering (DLS). Characterization data demonstrated that the particles were crystalline in nature and spherical shaped with an average diameter of 12 nm. Measurements of cell viability, cell membrane integrity and intracellular production of reactive oxygen species have shown that the green synthesized Ag NPs were nontoxic to human lung epithelial A549 cells. This study demonstrated a simple, cost-effective and environmentally benign synthesis of Ag NPs with excellent biocompatibility to human lung epithelial A549 cells. This preliminary in vitro investigation needs to be followed up by future studies with various biological systems.

  4. Inhibition effect of engineered silver nanoparticles to bloom forming cyanobacteria

    NASA Astrophysics Data System (ADS)

    Thuy Duong, Thi; Son Le, Thanh; Thu Huong Tran, Thi; Kien Nguyen, Trung; Ho, Cuong Tu; Hien Dao, Trong; Phuong Quynh Le, Thi; Chau Nguyen, Hoai; Dang, Dinh Kim; Thu Huong Le, Thi; Thu Ha, Phuong

    2016-09-01

    Silver nanoparticle (AgNP) has a wide range antibacterial effect and is extensively used in different aspects of medicine, food storage, household products, disinfectants, biomonitoring and environmental remediation etc. In the present study, we examined the growth inhibition effect of engineered silver nanoparticles against bloom forming cyanobacterial M. aeruginosa strain. AgNPs were synthesized by a chemical reduction method at room temperature and UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscope (TEM) showed that they presented a maximum absorption at 410 nm and size range between 10 and 18 nm. M. aeruginosa cells exposed during 10 d to AgNPs to a range of concentrations from 0 to 1 mg l-1. The changes in cell density and morphology were used to measure the responses of the M. aeruginosa to AgNPs. The control and treatment units had a significant difference in terms of cell density and growth inhibition (p < 0.05). Increasing the concentration of AgNPs, a reduction of the cell growths in all treatment was observed. The inhibition efficiency was reached 98.7% at higher concentration of AgNPs nanoparticles. The term half maximal effective concentration (EC50) based on the cell growth measured by absorbance at 680 nm (A680) was 0.0075 mg l-1. The inhibition efficiency was 98.7% at high concentration of AgNPs (1 mg l-1). Image of SEM and TEM reflected a shrunk and damaged cell wall indicating toxicity of silver nanoparticles toward M. aeruginosa.

  5. Preparation and antibacterial properties of Ag@polydopamine/graphene oxide sheet nanocomposite

    NASA Astrophysics Data System (ADS)

    Zhou, Hao; Liu, Yunfang; Chi, Weidong; Yu, Changyuan; Yu, Yingjie

    2013-10-01

    Immobilization of silver nanoparticles (Ag NPs) on poly-dopamine (PDA) functionalized graphene oxide sheets (GOSs) were carried out by an easy in situ reduction method. The PDA layer was coated on the surface of the GOSs via the self-polymerization of dopamine under atmosphere condition. The PDA layer not only works as the chemisorption and reduction sites for silver ions to form Ag NPs but also stabilizes them. High-resolution transmission electron microscopy observation shows that the average size of the Ag NPs anchored on the PDA/GOS composite is about 2.8 nm. The inhibition zone diameter of the Ag@PDA/GOS nanocomposite is about 23.7 mm, whereas said diameter of the Ag NPs is only 18.5 mm. The minimum bactericidal concentration of the Ag@PDA/GOS nanocomposite is about 25 μg/ml that is only half of said concentration of the Ag NPs. The Ag@PDA/GOS nanocomposite exhibits an excellent antibacterial property.

  6. Green synthesis of xanthan conformation-based silver nanoparticles: antibacterial and catalytic application.

    PubMed

    Xu, Wei; Jin, Weiping; Lin, Liufeng; Zhang, Chunlan; Li, Zhenshun; Li, Yan; Song, Rong; Li, Bin

    2014-01-30

    Silver nanoparticles (Ag NPs) were green synthetized using xanthan gum (XG) dissolved in water as reducing and capping agent for the first time. The structure, morphology, and size of Ag NPs in XG aqueous solutions were investigated with UV-vis spectroscopy, transmission electron microscopy and Fourier transform infrared. The results indicated Ag NPs were integrated successfully in the XG matrix and the optical properties and morphology of Ag NPs could be regulated by the synthesis condition. The aggregation of the XG-bonded Ag NPs increased with storage, whereas the size barely changed. The assemble behavior was related to the XG conformation transition of denaturation and renaturation. The one spot formed Ag NPs showed favorable antibacterial effect on Escherichia coli and Staphyloccocus aureus and excellent catalytic capability of 4-nitrophenol reduction. This work provided a feasible method to detect the biopolymer space structure transition through the intensity of metal nanoparticles labeled on the chain. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  7. One-pot facile green synthesis of biocidal silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Nudrat Hazarika, Shabiha; Gupta, Kuldeep; Shamin, Khan Naseem Ahmed Mohammed; Bhardwaj, Pushpender; Boruah, Ratan; Yadav, Kamlesh K.; Naglot, Ashok; Deb, P.; Mandal, M.; Doley, Robin; Veer, Vijay; Baruah, Indra; Namsa, Nima D.

    2016-07-01

    The plant root extract mediated green synthesis method produces monodispersed spherical shape silver nanoparticles (AgNPs) with a size range of 15-30 nm as analyzed by atomic force and transmission electron microscopy. The material showed potent antibacterial and antifungal properties. Synthesized AgNPs display a characteristic surface plasmon resonance peak at 420 nm in UV-Vis spectroscopy. X-ray diffractometer analysis revealed the crystalline and face-centered cubic geometry of in situ prepared AgNPs. Agar well diffusion and a colony forming unit assay demonstrated the potent biocidal activity of AgNPs against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas diminuta and Mycobacterium smegmatis. Intriguingly, the phytosynthesized AgNPs exhibited activity against pathogenic fungi, namely Trichophyton rubrum, Aspergillus versicolor and Candida albicans. Scanning electron microscopy observations indicated morphological changes in the bacterial cells incubated with silver nanoparticles. The genomic DNA isolated from the bacteria was incubated with an increasing concentration of AgNPs and the replication fidelity of 16S rDNA was observed by performing 18 and 35 cycles PCR. The replication efficiency of small (600 bp) and large (1500 bp) DNA fragments in the presence of AgNPs were compromised in a dose-dependent manner. The results suggest that the Thalictrum foliolosum root extract mediated synthesis of AgNPs could be used as a promising antimicrobial agent against clinical pathogens.

  8. Preparation of core-shell Ag@CeO2 nanocomposite by LSPR photothermal induced interface reaction

    NASA Astrophysics Data System (ADS)

    Zhong, H. X.; Wei, Y.; Yue, Y. Z.; Zhang, L. H.; Liu, Y.

    2016-04-01

    The core-shell structure of Ag@CeO2 was prepared by a novel and facile method, which was based on the photothermal effect of localized surface plasmon resonance (LSPR). Nanoparticles (NPs) of Ag were dispersed in a solution containing citric acid, ethylene glycol and cerium nitrate, then under irradiation, Ag NPs generated heat from LSPR and the heat-induced polymerization reaction in the interface between Ag and the sol resulted in cerium gel formation only on the surface of the Ag NPs. After calcination, Ag@CeO2 was successfully obtained, then Ag@CeO2/SiO2 was prepared by loading Ag@CeO2 on SiO2. The resultant catalyst exhibited favorable activity and stability for CO oxidation. The preparation method proposed here should be extendable to other composites with metallic cores and oxide shells in which the metallic nanoparticle possesses LSPR properties.

  9. Calix[4]arene-Functionalised Silver Nanoparticles as Hosts for Pyridinium-Loaded Gold Nanoparticles as Guests.

    PubMed

    Vita, Francesco; Boccia, Alice; Marrani, Andrea G; Zanoni, Robertino; Rossi, Francesca; Arduini, Arturo; Secchi, Andrea

    2015-10-19

    A series of lipophilic gold nanoparticles (AuNPs) circa 5 nm in diameter and having a mixed organic layer consisting of 1-dodecanethiol and 1-(11-mercaptoundecyl) pyridinium bromide was synthesised by reacting tetraoctylammonium bromide stabilised AuNPs in toluene with different mixtures of the two thiolate ligands. A bidentate ω-alkylthiolate calix[4]arene derivative was instead used as a functional protecting layer on AgNPs of approximately 3 nm. The functionalised nanoparticles were characterised by transmission electron microscopy (TEM), and by UV/Vis and X-ray photoelectron spectroscopy (XPS). Recognition of the pyridinium moieties loaded on the AuNPs by the calix[4]arene units immobilised on the AgNPs was demonstrated in solution of weakly polar solvents by UV/Vis titrations and DLS measurements. The extent of Au-AgNPs aggregation, shown through the low-energy shift of their surface plasmon bands (SPB), was strongly dependent on the loading of the pyridinium moieties present in the organic layer of the AuNPs. Extensive aggregation between dodecanethiol-capped AuNPs and the Ag calix[4]arene-functionalised NPs was also promoted by the action of a simple N-octyl pyridinium difunctional supramolecular linker. This linker can interdigitate through its long fatty tail in the organic layer of the dodecanethiol-capped AuNPs, and simultaneously interact through its pyridinium moiety with the calix[4]arene units at the surface of the modified AgNPs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Preparation and characterization of antibacterial orthodontic resin containing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Lee, Sang Jin; Heo, Min; Lee, Donghyun; Han, Seungheui; Moon, Ji-Hoi; Lim, Ho-Nam; Kwon, Il Keun

    2018-02-01

    In this study, we developed a hybrid dental resin containing silver nanoparticle (AgNPs) to eliminate periodontal disease causing bacteria such as streptococcus mutans (S. mutans) and streptococcus sobrinus (S. sobrinus). The silver nanoparticles enables the resin to prevent oral pathogen growth during orthodontic therapy. First, AgNPs were directly synthesized in dimethylformamide (DMF) solvent with a capping agent. Second, pure orthodontic primer was mixed with the synthesized AgNPs solvent-slurry followed by photocuring. The resultant material was characterized by physicochemical characterization. Finally, an in vitro antimicrobial test was carried out. The results showed that the AgNPs were fully synthesized and clearly embedded in dental resin. In the bacterial test, the dental resin containing AgNPs showed potent antimicrobial activity against two kinds of bacteria. In conclusion, our methodology may allow for the generation of a wide range of dental resin and composite products which inhibit periodontitis causing bacteria.

  11. Characterization, Antibacterial and Antioxidant Properties of Silver Nanoparticles Synthesized from Aqueous Extracts of Allium sativum, Zingiber officinale, and Capsicum frutescens.

    PubMed

    Otunola, Gloria Aderonke; Afolayan, Anthony Jide; Ajayi, Emmanuel Olusegun; Odeyemi, Samuel Wale

    2017-07-01

    Herbal drug delivery is limited by poor solubility and bioavailability which can be overcome with suitable nanomaterials that will enhance their pharmacokinetics and performance. This study aimed to analyze the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from three spices. AgNPs were prepared using 0.1 M silver nitrate and aqueous extracts of Allium sativum L. (garlic), Zingiber officinale Rosc. (ginger), and Capsicum frutescens L. (cayenne pepper). The AgNPs were characterized using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The AgNPs were formed within an hour of the reaction and showed maximum UV-Vis absorption in the 375-480 nm range. SEM and TEM revealed well-dispersed spherical particles with little agglomeration, average sizes of 3-6 nm, 3-22 nm, and 3-18 nm for garlic, ginger, and cayenne pepper, respectively. FTIR showed that amine, protein, phenolic, aromatic, and alkynes groups contributed to AgNP synthesis and XRD confirmed their crystalline and face-centered cubic nature. Antibacterial action of the AgNPs was in the following order: ginger (minimum inhibitory concentration [MIC] <25 μg/mL) > garlic> cayenne pepper (MIC 125 μg/mL). Antioxidant action showed cayenne pepper > ginger > garlic (inhibitory concentration 50% [IC50]: 40, 240, and 250 μg/mL, respectively) against 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and garlic > cayenne pepper > ginger (IC50: <31.25, 40, and 120 μg/mL, respectively) against 1,1-diphenyl-2-picrylhydrazyl. Optimization of this green synthesis would support the production of AgNPs with great therapeutic potentials. The synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from garlic, ginger and cayenne pepper were evaluatedThe AgNPs formed were characterized

  12. The effect of TiO{sub 2} and Ag nanoparticles on reproduction and development of Drosophila melanogaster and CD-1 mice

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Philbrook, Nicola A., E-mail: 3nap@queensu.ca; Department of Biomedical and Molecular Sciences, Botterell Hall, 5th Floor, Queen's University, 18 Stuart Street, Kingston, Ontario, Canada K7L 3N6; Winn, Louise M., E-mail: winnl@queensu.ca

    2011-12-15

    In the last two decades, nanoparticles (NPs) have found applications in a wide variety of consumer goods. Titanium dioxide (TiO{sub 2}) and silver (Ag) NPs are both found in cosmetics and foods, but their increasing use is of concern due to their ability to be taken up by biological systems. While there are some reports of TiO{sub 2} and Ag NPs affecting complex organisms, their effects on reproduction and development have been largely understudied. Here, the effects of orally administered TiO{sub 2} or Ag NPs on reproduction and development in two different model organisms were investigated. TiO{sub 2} NPs reducedmore » the developmental success of CD-1 mice after a single oral dose of 100 or 1000 mg/kg to dams, resulting in a statistically significant increase in fetal deformities and mortality. Similarly, TiO{sub 2} NP addition to food led to a significant progeny loss in the fruit fly, Drosophila, as shown by a decline in female fecundity. Ag NP administration resulted in an increase in the mortality of fetal mice. Similarly in Drosophila, Ag NP feeding led to a significant decrease in developmental success, but unlike TiO{sub 2} NP treatment, there was no decline in fecundity. The distinct response associated with each type of NP likely reflects differences in NP administration as well as the biology of the particular model. Taken together, however, this study warns that these common NPs could be detrimental to the reproductive and developmental health of both invertebrates and vertebrates.« less

  13. Fate of Zinc and Silver Engineered Nanoparticles in ...

    EPA Pesticide Factsheets

    Engineered zinc oxide (ZnO) and silver (Ag) nanoparticles (NPs) used in consumer products are largely released into the environment through the wastewater stream. Limited information is available regarding the transformations they undergo during their transit through sewerage systems before reaching wastewater treatment plants. To address this knowledge gap, laboratory-scale systems fed with raw wastewater were used to evaluate the transformation of ZnO- and Ag-NPs within sewerage transfer networks. Two experimental systems were established and spiked with either Ag- and ZnO-NPs or with their dissolved salts, and the wastewater influent and effluent samples from both systems were thoroughly characterised. X-ray absorption spectroscopy (XAS) was used to assess the extent of the chemical transformation of both forms of Zn and Ag during transport through the model systems. The results indicated that both ZnO- and Ag-NPs underwent significant transformation during their transport through the sewerage network. Reduced sulphur species represented the most important endpoint for these NPs in the sewer with slight differences in terms of speciation; ZnO converted largely to Zn sulfide, while Ag was also sorbed to cysteine and histidine. Importantly, both ionic Ag and Ag-NPs formed secondary Ag sulfide nanoparticles in the sewerage network as revealed by TEM analysis. Ag-cysteine was also shown to be a major species in biofilms. These results were verified in the

  14. Structural and thermal properties of silk fibroin - Silver nanoparticles composite films

    NASA Astrophysics Data System (ADS)

    Shivananda, C. S.; Rao B, B. Lakshmeesha; Shetty, G. Rajesh; Sangappa, Y.

    2018-05-01

    In this work, silk fibroin-silver nanoparticles (SF-AgNPs) composite films have been prepared by simple solution casting method. The composite films were examined for structural and thermal properties using X-ray diffraction (XRD), thermogravimatric (TGA) and differential scanning calorimetry (DSC) analysis. The XRD results showed that with the introduction of AgNPs in the silk fibroin matrix the amorphous nature of the silk fibroin decreases with increasing nanoparticles concentration. The silk fibroin films possess good thermal stability with the presence of AgNPs.

  15. An investigation of localised surface plasmon resonance (LSPR) of Ag nanoparticles produced by pulsed laser deposition (PLD) technique

    NASA Astrophysics Data System (ADS)

    Gezgin, Serap Yiǧit; Kepceoǧlu, Abdullah; Kılıç, Hamdi Şükür

    2017-02-01

    Noble metal nano-structures such as Ag, Cu, Au are used commonly to increase power conversion efficiency of the solar cell by using their surface plasmons. The plasmonic metal nanoparticles of Ag among others that have strong LSPR in near UV range. They increase photon absorbance via embedding in the active semiconductor of the solar cell. Thin films of Ag are grown in the desired particle size and interparticle distance easily and at low cost by PLD technique. Ag nanoparticle thin films were grown on micro slide glass at 25-36 mJ laser pulse energies under by PLD using ns-Nd:YAG laser. The result of this work have been presented by carrying out UV-VIS and AFM analysis. It was concluded that a laser energy increases, the density and size of Ag-NPs arriving on the substrate increases, and the interparticle distance was decreases. Therefore, LSPR wavelength shifts towards to longer wavelength region.

  16. Plasmon enhanced upconversion luminescence of NaYF4:Yb,Er@SiO2@Ag core-shell nanocomposites for cell imaging.

    PubMed

    Yuan, Peiyan; Lee, Yih Hong; Gnanasammandhan, Muthu Kumara; Guan, Zhenping; Zhang, Yong; Xu, Qing-Hua

    2012-08-21

    NaYF(4):Yb,Er@SiO(2)@Ag core-shell nanocomposites were prepared to investigate metal-enhanced upconversion luminescence. Two sizes (15 and 30 nm) of Ag nanoparticles were used. The emission intensity of the upconversion nanocrystals was found to be strongly modulated by the presence of Ag nanoparticles (NPs) on the outer shell layer of the nanocomposites. The extent of modulation depended on the separation distance between Ag NPs and upconversion nanocrystals. The optimum upconversion luminescence enhancement was observed at a separation distance of 10 nm for Ag NPs with two different sizes (15 and 30 nm). A maximum upconversion luminescence enhancement of 14.4-fold was observed when 15 nm Ag nanoparticles were used and 10.8-fold was observed when 30 nm Ag NPs were used. The separation distance dependent emission intensity is ascribed to the competition between energy transfer and enhanced radiative decay rates. The biocompatibility of the nanocomposites was significantly improved by surface modification with DNA. The biological imaging capabilities of these nanocomposites were demonstrated using B16F0 cells.

  17. Rapid chromatographic separation of dissoluble Ag(I) and silver-containing nanoparticles of 1-100 nanometer in antibacterial products and environmental waters.

    PubMed

    Zhou, Xiao-Xia; Liu, Rui; Liu, Jing-Fu

    2014-12-16

    Sensitive and rapid methods for speciation analysis of nanoparticulate Ag (NAg) and Ag(I) in complex matrices are urgently needed for understanding the environmental effects and biological toxicity of silver nanoparticles (AgNPs). Herein we report the development of a universal liquid chromatography (LC) method for rapid and high resolution separation of dissoluble Ag(I) from nanoparticles covering the entire range of 1-100 nm in 5 min. By using a 500 Å poresize amino column, and an aqueous mobile phase containing 0.1% (v/v) FL-70 (a surfactant) and 2 mM Na2S2O3 at a flow rate of 0.7 mL/min, all the nanoparticles of various species such as Ag and Ag2S were eluted in one fraction, while dissoluble Ag(I) was eluted as a baseline separated peak. The dissoluble Ag(I) was quantified by the online coupled ICP-MS with a detection limit of 0.019 μg/L. The NAg was quantified by subtracting the dissoluble Ag(I) from the total Ag content, which was determined by ICP-MS after digestion of the sample without LC separation. While the addition of FL-70 and Na2S2O3 into the mobile phase is essential to elute NAg and Ag(I) from the column, the use of 500 Å poresize column is the key to baseline separation of Ag(I) from ∼ 1 nm AgNPs. The feasibility of the proposed method was demonstrated in speciation analysis of dissoluble Ag(I) and NAg in antibacterial products and environmental waters, with very good chromatographic repeatability (relative standard deviations) in both peak area (<2%) and retention time (<0.6%), excellent spiked recoveries in the range of 84.7-102.7% for Ag(I) and 81.3-106.3% for NAg. Our work offers a novel approach to rapid and baseline separation of dissoluble metal ions from their nanoparticulate counterparts covering the whole range of 1-100 nm.

  18. Ag-graphene hybrid conductive ink for writing electronics.

    PubMed

    Xu, L Y; Yang, G Y; Jing, H Y; Wei, J; Han, Y D

    2014-02-07

    With the aim of preparing a method for the writing of electronics on paper by the use of common commercial rollerball pens loaded with conductive ink, hybrid conductive ink composed of Ag nanoparticles (15 wt%) and graphene-Ag composite nanosheets (0.15 wt%) formed by depositing Ag nanoparticles (∼10 nm) onto graphene sheets was prepared for the first time. Owing to the electrical pathway effect of graphene and the decreased contact resistance of graphene junctions by depositing Ag nanoparticles (NPs) onto graphene sheets, the concentration of Ag NPs was significantly reduced while maintaining high conductivity at a curing temperature of 100 ° C. A typical resistivity value measured was 1.9 × 10(-7) Ω m, which is 12 times the value for bulk silver. Even over thousands of bending cycles or rolling, the resistance values of writing tracks only increase slightly. The stability and flexibility of the writing circuits are good, demonstrating the promising future of this hybrid ink and direct writing method.

  19. Eco-friendly microwave-assisted green and rapid synthesis of well-stabilized gold and core-shell silver-gold nanoparticles.

    PubMed

    El-Naggar, Mehrez E; Shaheen, Tharwat I; Fouda, Moustafa M G; Hebeish, Ali A

    2016-01-20

    Herein, we present a new approach for the synthesis of gold nanoparticles (AuNPs) individually and as bimetallic core-shell nanoparticles (AgNPs-AuNPs). The novelty of the approach is further maximized by using curdlan (CRD) biopolymer to perform the dual role of reducing and capping agents and microwave-aided technology for affecting the said nanoparticles with varying concentrations in addition to those affected by precursor concentrations. Thus, for preparation of AuNPs, curdlan was solubilized in alkali solution followed by an addition of tetrachloroauric acid (HAuCl4). The curdlan solution containing HAuCl4 was then subjected to microwave radiation for up to 10 min. The optimum conditions obtained with the synthesis of AuNPs were employed for preparation of core-shell silver-gold nanoparticles by replacing definite portion of HAuCl4 with an equivalent portion of silver nitrate (AgNO3). The portion of AgNO3 was added initially and allowed to be reduced by virtue of the dual role of curdlan under microwave radiation. The corresponding portion of HAuCl4 was then added and allowed to complete the reaction. Characterization of AuNPs and AgNPs-AuNPs core-shell were made using UV-vis spectra, TEM, FTIR, XRD, zeta potential, and AFM analysis. Accordingly, strong peaks of the colloidal particles show surface plasmon resonance (SPR) at maximum wavelength of 540 nm, proving the formation of well-stabilized gold nanoparticles. TEM investigations reveal that the major size of AuNPs formed at different Au(+3)concentration lie below 20 nm with narrow size distribution. Whilst, the SPR bands of AgNPs-AuNPs core-shell differ than those obtained from original AgNPs (420 nm) and AuNPs (540 nm). Such shifting due to SPR of Au nanoshell deposited onto AgNPs core was significantly affected by the variation of bimetallic ratios applied. TEM micrographs show variation in contrast between dark silver core and the lighter gold shell. Increasing the ratio of silver ions leads to

  20. Coalescence of functional gold and monodisperse silver nanoparticles mediated by black Panax ginseng Meyer root extract

    PubMed Central

    Wang, Dandan; Markus, Josua; Kim, Yeon-Ju; Wang, Chao; Jiménez Pérez, Zuly Elizabeth; Ahn, Sungeun; Aceituno, Verónica Castro; Mathiyalagan, Ramya; Yang, Deok Chun

    2016-01-01

    A rapid biological synthesis of multifunctional gold nanoparticle (AuNp) and monodisperse silver nanoparticle (AgNp) was achieved by an aqueous extract of black Panax ginseng Meyer root. The physicochemical transformation into black ginseng (BG) greatly enhanced the pharmacological activities of white ginseng and its minor ginsenoside content. The optimal temperature conditions and kinetics of bioreduction were investigated. Formation of BG-AuNps and BG-AgNps was verified by ultraviolet–visible spectrophotometry at 548 and 412 nm, respectively. The biosynthesized BG-AgNps were spherical and monodisperse with narrow distribution, while BG-AuNps were icosahedral-shaped and moderately polydisperse. Synthesized nanoparticles exhibited long-term stability in buffers of pH 7.0–8.0 and biological media (5% bovine serum albumin) at an ambient temperature and at 37°C. BG-AgNps showed effective antibacterial activity against Escherichia coli and Staphylococcus aureus. BG-AuNps and BG-AgNps demonstrated increased scavenging activity against 2,2-diphenyl-1-picrylhydrazyl free radicals. In addition, BG-AuNps and BG-AgNps were nontoxic to HaCaT and MCF-7 cells; the latter showed no cytotoxicity at concentrations lower than 10 µg/mL. At higher concentrations, BG-AgNps exhibited apparent apoptotic activity in MCF-7 breast cancer cell line through reactive oxygen species generation and nuclear fragmentation. PMID:28008248

  1. The photovoltaic performance of Ag2S quantum dots-sensitized solar cells using plasmonic Au nanoparticles/TiO2 working electrodes

    NASA Astrophysics Data System (ADS)

    Badawi, Ali; Mostafa, Nasser Y.; Al-Hosiny, Najm M.; Merazga, Amar; Albaradi, Ateyyah M.; Abdel-Wahab, F.; Atta, A. A.

    2018-06-01

    The photovoltaic performance of silver sulfide (Ag2S) quantum dots-sensitized solar cells (QDSSCs) using different concentrations (0, 0.05, 0.1, 0.3 and 0.5 wt.%) of plasmonic Au nanoparticles (NPs)/titania (TiO2) electrodes has been investigated. Ag2S quantum dots (QDs) were adsorbed onto the Au NPs/titania electrodes using the successive ionic layer adsorption and reaction (SILAR) deposition technique. The morphological properties of the Au NPs and the prepared titania electrodes were characterized using transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. The energy-dispersive X-ray (EDX) spectra of the bare titania and Ag2S QDs-sensitized titania electrodes were recorded. The optical properties of the prepared Ag2S QDs-sensitized titania electrodes were measured using a UV-visible spectrophotometer. The estimated energy band gap of Ag2S QDs-sensitized titania electrodes is 1.96 eV. The photovoltaic performance of the assembled Ag2S QDSSCs was measured under 100 mW/cm2 solar illumination. The optimal photovoltaic parameters were obtained as follows: open circuit voltage Voc = 0.50 V, current density Jsc = 3.18 mA/cm2, fill factor (FF) = 0.35 and energy conversion efficiency η = 0.55% for 0.3 wt.% of Au NPs/titania electrode. These results are attributed to the enhancement in the absorption and decrease in the electron-hole pairs recombination rate. The open circuit voltage decay (OCVD) measurements of the assembled Ag2S QDSSCs were measured. The calculated electron lifetime (τ) in Ag2S QDSSCs with Au NPs/titania electrodes is at least one order of magnitude more than that with bare titania electrode. The cut-on-cut-off cycles of the solar illumination measurements show the rapid sensitivity and good reproducibility of the assembled Ag2S QDSSCs.

  2. Phytotoxicity, accumulation and transport of silver nanoparticles by Arabidopsis thaliana.

    PubMed

    Geisler-Lee, Jane; Wang, Qiang; Yao, Ying; Zhang, Wen; Geisler, Matt; Li, Kungang; Huang, Ying; Chen, Yongsheng; Kolmakov, Andrei; Ma, Xingmao

    2013-05-01

    The widespread availability of nano-enabled products in the global market may lead to the release of a substantial amount of engineered nanoparticles in the environment, which frequently display drastically different physiochemical properties than their bulk counterparts. The purpose of the study was to evaluate the impact of citrate-stabilised silver nanoparticles (AgNPs) on the plant Arabidopsis thaliana at three levels, physiological phytotoxicity, cellular accumulation and subcellular transport of AgNPs. The monodisperse AgNPs of three different sizes (20, 40 and 80 nm) aggregated into much larger sizes after mixing with quarter-strength Hoagland solution and became polydisperse. Immersion in AgNP suspension inhibited seedling root elongation and demonstrated a linear dose-response relationship within the tested concentration range. The phytotoxic effect of AgNPs could not be fully explained by the released silver ions. Plants exposed to AgNP suspensions bioaccumulated higher silver content than plants exposed to AgNO3 solutions (Ag(+) representative), indicating AgNP uptake by plants. AgNP toxicity was size and concentration dependent. AgNPs accumulated progressively in this sequence: border cells, root cap, columella and columella initials. AgNPs were apoplastically transported in the cell wall and found aggregated at plasmodesmata. In all the three levels studied, AgNP impacts differed from equivalent dosages of AgNO3.

  3. Synthesis and characterization of manganese diselenide nanoparticles (MnSeNPs): Determination of capsaicin by using MnSeNP-modified glassy carbon electrode.

    PubMed

    Sukanya, Ramaraj; Sakthivel, Mani; Chen, Shen-Ming; Chen, Tse-Wei; Al-Hemaid, Fahad M A; Ajmal Ali, M; Elshikh, Mohamed Soliman

    2018-06-02

    A new type of manganese diselenide nanoparticles (MnSeNPs) was synthesized by using a hydrothermal method. Their surface morphology, crystallinity and elemental distribution were characterized by using transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy which scrutinize the formation of the NPs. The NPs were coated on a glassy carbon electrode (GCE), and electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were applied to study the electroanalytical properties towards the oxidation of the food additive capsaicin. The modified GCE displays lower charge transfer resistance (R ct  = 29.52 Ω), a larger active surface area (0.089 cm 2 /g, and more efficient electrochemical oxidation of capsaicin compared to a MnS 2 /GCE and a bare GCE. The oxidation peak potential is 0.43 V (vs. Ag/AgCl) which is lower than that of previously reported GCEs. The sensor has a detection limit as low as 0.05 μM and an electrochemical sensitivity of 2.41 μA μM -1  cm -2 . The method was applied to the determination of capsaicin in pepper samples. Graphical abstract Electrochemical determination of capsaicin in pepper extract by using MnSeNPs modified electrode.

  4. Biosynthesis of silver nanoparticles using Momordica charantia leaf broth: Evaluation of their innate antimicrobial and catalytic activities.

    PubMed

    Ajitha, B; Reddy, Y Ashok Kumar; Reddy, P Sreedhara

    2015-05-01

    Silver nanoparticles (AgNPs) were prepared through green route with the aid of Momordica charantia leaf extract as both reductant and stabilizer. X-ray diffraction pattern (XRD) and selected area electron diffraction (SAED) fringes revealed the structure of AgNPs as face centered cubic (fcc). Morphological studies elucidate the nearly spherical AgNPs formation with particle size in nanoscale. Biosynthesized AgNPs were found to be photoluminescent and UV-Vis absorption spectra showed one surface plasmon resonance peak (SPR) at 424nm attesting the spherical nanoparticles formation. XPS study provides the surface chemical nature and oxidation state of the synthesized nanoparticles. FTIR spectra ascertain the reduction and capping nature of phytoconstituents of leaf extract in AgNPs synthesis. Further, these AgNPs showed effective antimicrobial activity against tested pathogens and thus applicable as potent antimicrobial agent. In addition, the synthesized AgNPs were observed to have an excellent catalytic activity on the reduction of methylene blue by M. charantia which was confirmed by the decrement in maximum absorbance values of methylene blue with respect to time and is ascribed to electron relay effect. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Ag-nanoparticles-decorated NiO-nanoflakes grafted Ni-nanorod arrays stuck out of porous AAO as effective SERS substrates.

    PubMed

    Zhou, Qitao; Meng, Guowen; Huang, Qing; Zhu, Chuhong; Tang, Haibin; Qian, Yiwu; Chen, Bin; Chen, Bensong

    2014-02-28

    NiO-nanoflakes (NiO-NFs) grafted Ni-nanorod (Ni-NR) arrays stuck out of the porous anodic aluminum oxide (AAO) template are achieved by a combinatorial process of AAO-confined electrodeposition of Ni-NRs, selectively etching part of the AAO template to expose the Ni-NRs, wet-etching the exposed Ni-NRs in ammonia to obtain Ni(OH)2-NFs grafted onto the cone-shaped Ni-NRs, and annealing to transform Ni(OH)2-NFs in situ into NiO-NFs. By top-view sputtering, Ag-nanoparticles (Ag-NPs) are decorated on each NiO-NFs grafted Ni-NR (denoted as NiO-NFs@Ni-NR). The resultant Ag-NPs-decorated NiO-NFs@Ni-NR (denoted as Ag-NPs@NiO-NFs@Ni-NR) arrays exhibit not only strong surface-enhanced Raman scattering (SERS) activity but also reproducible SERS-signals over the whole array. It is demonstrated that the strong SERS-activity is mainly ascribed to the high density of sub-10 nm gaps (hot spots) between the neighboring Ag-NPs, the semiconducting NiO-NFs induced chemical enhancement effect, and the lightning rod effect of the cone-shaped Ni-NRs. The three-level hierarchical nanostructure arrays stuck out of the AAO template can be utilized to probe polychlorinated biphenyls (PCBs, a kind of global environmental hazard) with a concentration as low as 5 × 10(-6) M, showing promising potential in SERS-based rapid detection of organic environmental pollutants.

  6. Tyrosine- and tryptophan-coated gold nanoparticles inhibit amyloid aggregation of insulin.

    PubMed

    Dubey, Kriti; Anand, Bibin G; Badhwar, Rahul; Bagler, Ganesh; Navya, P N; Daima, Hemant Kumar; Kar, Karunakar

    2015-12-01

    Here, we have strategically synthesized stable gold (AuNPs(Tyr), AuNPs(Trp)) and silver (AgNPs(Tyr)) nanoparticles which are surface functionalized with either tyrosine or tryptophan residues and have examined their potential to inhibit amyloid aggregation of insulin. Inhibition of both spontaneous and seed-induced aggregation of insulin was observed in the presence of AuNPs(Tyr), AgNPs(Tyr), and AuNPs(Trp) nanoparticles. These nanoparticles also triggered the disassembly of insulin amyloid fibrils. Surface functionalization of amino acids appears to be important for the inhibition effect since isolated tryptophan and tyrosine molecules did not prevent insulin aggregation. Bioinformatics analysis predicts involvement of tyrosine in H-bonding interactions mediated by its C=O, -NH2, and aromatic moiety. These results offer significant opportunities for developing nanoparticle-based therapeutics against diseases related to protein aggregation.

  7. Plasmid DNA linearization in the antibacterial action of a new fluorescent Ag nanoparticle-paracetamol dimer composite

    NASA Astrophysics Data System (ADS)

    Sahoo, Amaresh Kumar; Sk, Md Palashuddin; Ghosh, Siddhartha Sankar; Chattopadhyay, Arun

    2011-10-01

    Herein, we report the generation of a composite comprised of p-hydroxyacetanilide dimer and Ag nanoparticles (NPs) by reaction of AgNO3 and p-hydroxyacetanilide. The formation of the composite was established by UV-vis, FTIR and NMR spectroscopy, transmission electron microscopy and X-ray diffraction along with substantiation by mass spectrometry. Interestingly, the composite exhibited an emission spectrum with a peak at 435 nm when excited by light of wavelength 320 nm. The composite showed superior antimicrobial activity with respect to its individual components against a wide range of Gram positive and Gram negative bacteria at relatively low concentrations of Ag NPs and at which there was no apparent cytotoxicity against mammalian cells. Our results suggest that the composite strongly interacted with the bacterial cell walls leading to cell bursting. Interestingly, enhancement in the reactive oxygen species (ROS) generation in bacteria was observed in the presence of the composite. It is proposed that the ROS generation led to oxidation of the dimer to N-acetyl-p-benzoquinone imine (NAPQI). The generated NAPQI acted as a DNA gyrase inhibitor causing cell death following linearization of DNA.Herein, we report the generation of a composite comprised of p-hydroxyacetanilide dimer and Ag nanoparticles (NPs) by reaction of AgNO3 and p-hydroxyacetanilide. The formation of the composite was established by UV-vis, FTIR and NMR spectroscopy, transmission electron microscopy and X-ray diffraction along with substantiation by mass spectrometry. Interestingly, the composite exhibited an emission spectrum with a peak at 435 nm when excited by light of wavelength 320 nm. The composite showed superior antimicrobial activity with respect to its individual components against a wide range of Gram positive and Gram negative bacteria at relatively low concentrations of Ag NPs and at which there was no apparent cytotoxicity against mammalian cells. Our results suggest that the

  8. Antibacterial and Cytotoxic Efficacy of Extracellular Silver Nanoparticles Biofabricated from Chromium Reducing Novel OS4 Strain of Stenotrophomonas maltophilia

    PubMed Central

    Oves, Mohammad; Khan, Mohammad Saghir; Zaidi, Almas; Ahmed, Arham S.; Ahmed, Faheem; Ahmad, Ejaz; Sherwani, Asif; Owais, Mohammad; Azam, Ameer

    2013-01-01

    Biofabricated metal nanoparticles are generally biocompatible, inexpensive, and ecofriendly, therefore, are used preferably in industries, medical and material science research. Considering the importance of biofabricated materials, we isolated, characterized and identified a novel bacterial strain OS4 of Stenotrophomonas maltophilia (GenBank: JN247637.1). At neutral pH, this Gram negative bacterial strain significantly reduced hexavalent chromium, an important heavy metal contaminant found in the tannery effluents and minings. Subsequently, even at room temperature the supernatant of log phase grown culture of strain OS4 also reduced silver nitrate (AgNO3) to generate nanoparticles (AgNPs). These AgNPs were further characterized by UV–visible, Nanophox particle size analyzer, XRD, SEM and FTIR. As evident from the FTIR data, plausibly the protein components of supernatant caused the reduction of AgNO3. The cuboid and homogenous AgNPs showed a characteristic UV-visible peak at 428 nm with average size of ∼93 nm. The XRD spectra exhibited the characteristic Bragg peaks of 111, 200, 220 and 311 facets of the face centred cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature. From the nanoparticle release kinetics data, the rapid release of AgNPs was correlated with the particle size and increasing surface area of the nanoparticles. A highly significant antimicrobial activity against medically important bacteria by the biofabricated AgNPs was also revealed as decline in growth of Staphylococcus aureus (91%), Escherichia coli (69%) and Serratia marcescens (66%) substantially. Additionally, different cytotoxic assays showed no toxicity of AgNPs to liver function, RBCs, splenocytes and HeLa cells, hence these particles were safe to use. Therefore, this novel bacterial strain OS4 is likely to provide broad spectrum benefits for curing chromium polluted sites, for biofabrication of AgNPs and ultimately in the nanoparticle based

  9. Trichoderma koningii assisted biogenic synthesis of silver nanoparticles and evaluation of their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Tripathi, R. M.; Gupta, Rohit Kumar; Shrivastav, Archana; Singh, M. P.; Shrivastav, B. R.; Singh, Priti

    2013-09-01

    The present study demonstrates the biosynthesis of silver nanoparticles using Trichoderma koningii and evaluation of their antibacterial activity. Trichoderma koningii secretes proteins and enzymes that act as reducing and capping agent. The biosynthesized silver nanoparticles (AgNPs) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) and x-ray diffraction (XRD). UV-Vis spectra showed absorbance peak at 413 nm corresponding to the surface plasmon resonance of silver nanoparticles. DLS was used to find out the size distribution profile. The size and morphology of the AgNPs was determined by TEM, which shows the formation of spherical nanoparticles in the size range of 8-24 nm. X-ray diffraction showed intense peaks corresponding to the crystalline silver. The antibacterial activity of biosynthesized AgNPs was evaluated by growth curve and inhibition zone and it was found that the AgNPs show potential effective antibacterial activity.

  10. Green synthesis and antibacterial effects of aqueous colloidal solutions of silver nanoparticles using camomile terpenoids as a combined reducing and capping agent.

    PubMed

    Parlinska-Wojtan, Magdalena; Kus-Liskiewicz, Małgorzata; Depciuch, Joanna; Sadik, Omowunmi

    2016-08-01

    Green synthesis method using camomile extract was applied to synthesize silver nanoparticles to tune their antibacterial properties merging the synergistic effect of camomile and Ag. Scanning transmission electron microscopy revealed that camomile extract (CE) consisted of porous globular nanometer sized structures, which were a perfect support for Ag nanoparticles. The Ag nanoparticles synthesized with the camomile extract (AgNPs/CE) of 7 nm average sizes, were uniformly distributed on the CE support, contrary to the pure Ag nanoparticles synthesized with glucose (AgNPs/G), which were over 50 nm in diameter and strongly agglomerated. The energy dispersive X-ray spectroscopy chemical analysis showed that camomile terpenoids act as a capping and reducing agent being adsorbed on the surface of AgNPs/CE enabling their reduction from Ag(+) and preventing them from agglomeration. Fourier transform infrared and ultraviolet-visible spectroscopy measurements confirmed these findings, as the spectra of AgNPs/CE, compared to pure CE, did not contain the 1109 cm(-1) band, corresponding to -C-O groups of terpenoids and the peaks at 280 and 320 nm, respectively. Antibacterial tests using four bacteria strains showed that the AgNPs/CE performed five times better compared to CE AgNPs/G samples, reducing totally all the bacteria in 2 h.

  11. Coiled-coil forming peptides for the induction of silver nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Božič Abram, Sabina; Graduate School of Biomedicine, University of Ljubljana, Ljubljana 1000; Aupič, Jana

    Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at aroundmore » 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.« less

  12. Heteroassembled gold nanoparticles with sandwich-immunoassay LSPR chip format for rapid and sensitive detection of hepatitis B virus surface antigen (HBsAg).

    PubMed

    Kim, Jinwoon; Oh, Seo Yeong; Shukla, Shruti; Hong, Seok Bok; Heo, Nam Su; Bajpai, Vivek K; Chun, Hyang Sook; Jo, Cheon-Ho; Choi, Bong Gill; Huh, Yun Suk; Han, Young-Kyu

    2018-06-01

    This study aimed to develop a more sensitive method for the detection of hepatitis B surface antigen (HBsAg) using heteroassembled gold nanoparticles (AuNPs). A single layered localized surface plasmon resonance (LSPR) chip format was developed with antigen-antibody reaction-based detection symmetry using AuNPs, which detected HBsAg at 10 pg/mL. To further improve the detection limit, a modified detection format was fabricated by fixing a secondary antibody (to form a heteroassembled sandwich format) to the AuNP monolayer, which enhanced the detection sensitivity by about 100 times. The developed heteroassembled AuNPs sandwich-immunoassay LSPR chip format was able to detect as little as 100 fg/mL of HBsAg within 10-15 min. In addition, the heteroassembled AuNPs sandwich-immunoassay LSPR chip format did not show any non-specific binding to other tested antigens, including alpha fetoprotein (AFP), C-reactive protein (CRP), and prostate-specific antigen (PSA). These findings confirm that the proposed detection strategy of heteroassembled AuNPs sandwich-immunoassay LSPR chip format may provide a new platform for early diagnosis of various human diseases. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Photoreduction of carbon dioxide under visible light by ultra-small Ag nanoparticles doped into Co-ZIF-9.

    PubMed

    Chen, Mengmeng; Han, Lu; Zhou, Jie; Sun, Chunyi; Hu, Chengying; Wang, Xinlong; Su, Zhongmin

    2018-07-13

    Metal-organic frameworks (MOFs) are well-known porous materials able to adsorb CO 2 , and their performance in CO 2 reduction has attracted much attention from researchers. A classical Co-MOF, Co-ZIF-9, has been proposed as a novel photocatalyst for reducing CO 2 into chemical feedstocks. Herein, Co-ZIF-9 with a rod-like structure was obtained through reflux. Ultra-small silver nanoparticles (Ag NPs, smaller than 5 nm) were doped into Co-ZIF-9 by the photodeposition method. With the assistance of a photosensitizer, the resultant composite Ag@Co-ZIF-9 shows catalytic reactivity in converting CO 2 into CO under visible light irradiation. Compared with bare Co-ZIF-9, the photocatalytic performance of Ag@Co-ZIF-9 increases by more than twofold (around 28.4 μmol CO) and the selectivity is enhanced by about 20% (22.9 μmol H 2 ) for 0.5 h of irradiation. This demonstrates that Ag NPs doping may provide a possible way to promote the efficiency and selectivity of MOF materials in CO 2 photoreduction.

  14. Photoreduction of carbon dioxide under visible light by ultra-small Ag nanoparticles doped into Co-ZIF-9

    NASA Astrophysics Data System (ADS)

    Chen, Mengmeng; Han, Lu; Zhou, Jie; Sun, Chunyi; Hu, Chengying; Wang, Xinlong; Su, Zhongmin

    2018-07-01

    Metal–organic frameworks (MOFs) are well-known porous materials able to adsorb CO2, and their performance in CO2 reduction has attracted much attention from researchers. A classical Co-MOF, Co-ZIF-9, has been proposed as a novel photocatalyst for reducing CO2 into chemical feedstocks. Herein, Co-ZIF-9 with a rod-like structure was obtained through reflux. Ultra-small silver nanoparticles (Ag NPs, smaller than 5 nm) were doped into Co-ZIF-9 by the photodeposition method. With the assistance of a photosensitizer, the resultant composite Ag@Co-ZIF-9 shows catalytic reactivity in converting CO2 into CO under visible light irradiation. Compared with bare Co-ZIF-9, the photocatalytic performance of Ag@Co-ZIF-9 increases by more than twofold (around 28.4 μmol CO) and the selectivity is enhanced by about 20% (22.9 μmol H2) for 0.5 h of irradiation. This demonstrates that Ag NPs doping may provide a possible way to promote the efficiency and selectivity of MOF materials in CO2 photoreduction.

  15. Silver-cotton nanocomposite via in-situ synthesis of silver nanoparticles in self-controlling microfibrillar reactor

    USDA-ARS?s Scientific Manuscript database

    Silver nanoparticles (Ag NPs) are effective antimicrobial agents, but their application on the surface of a fiber renders them ineffective because Ag NPs are washable. In this study, a stable, non-leaching Ag-cotton nanocomposite was produced by the in-situ formation of Ag NPs in the microfibrillar ...

  16. Green Synthesis and Characterization of Silver Nanoparticles Using Citrullus lanatus Fruit Rind Extract

    PubMed Central

    Ndikau, Michael; Andala, Dickson M.; Masika, Eric

    2017-01-01

    The wide-scale application of silver nanoparticles (AgNPs) in areas such as chemical sensing, nanomedicine, and electronics has led to their increased demand. Current methods of AgNPs synthesis involve the use of hazardous reagents and toxic solvents. There is a need for the development of new methods of synthesizing AgNPs that use environmentally safe reagents and solvents. This work reports a green method where silver nanoparticles (AgNPs) were synthesized using silver nitrate and the aqueous extract of Citrullus lanatus fruit rind as the reductant and the capping agent. The optimized conditions for the AgNPs synthesis were a temperature of 80°C, pH 10, 0.001 M AgNO3, 250 g/L watermelon rind extract (WMRE), and a reactant ratio of 4 : 5 (AgNO3 to WMRE). The AgNPs were characterized by Ultraviolet-Visible (UV-Vis) spectroscopy exhibiting a λmax at 404 nm which was consistent with the spectra of spherical AgNPs within the wavelength range of 380–450 nm, and Cyclic Voltammetry (CV) results showed a distinct oxidation peak at +291 mV while the standard reference AgNPs (20 nm diameter) oxidation peak occurred at +290 mV, and Transmission Electron Microscopy (TEM) revealed spherical shaped AgNPs. The AgNPs were found to have an average diameter of 17.96 ± 0.16 nm. PMID:28316627

  17. Plasmon enhanced upconversion luminescence of NaYF4:Yb,Er@SiO2@Ag core-shell nanocomposites for cell imaging

    NASA Astrophysics Data System (ADS)

    Yuan, Peiyan; Lee, Yih Hong; Gnanasammandhan, Muthu Kumara; Guan, Zhenping; Zhang, Yong; Xu, Qing-Hua

    2012-07-01

    NaYF4:Yb,Er@SiO2@Ag core-shell nanocomposites were prepared to investigate metal-enhanced upconversion luminescence. Two sizes (15 and 30 nm) of Ag nanoparticles were used. The emission intensity of the upconversion nanocrystals was found to be strongly modulated by the presence of Ag nanoparticles (NPs) on the outer shell layer of the nanocomposites. The extent of modulation depended on the separation distance between Ag NPs and upconversion nanocrystals. The optimum upconversion luminescence enhancement was observed at a separation distance of 10 nm for Ag NPs with two different sizes (15 and 30 nm). A maximum upconversion luminescence enhancement of 14.4-fold was observed when 15 nm Ag nanoparticles were used and 10.8-fold was observed when 30 nm Ag NPs were used. The separation distance dependent emission intensity is ascribed to the competition between energy transfer and enhanced radiative decay rates. The biocompatibility of the nanocomposites was significantly improved by surface modification with DNA. The biological imaging capabilities of these nanocomposites were demonstrated using B16F0 cells.NaYF4:Yb,Er@SiO2@Ag core-shell nanocomposites were prepared to investigate metal-enhanced upconversion luminescence. Two sizes (15 and 30 nm) of Ag nanoparticles were used. The emission intensity of the upconversion nanocrystals was found to be strongly modulated by the presence of Ag nanoparticles (NPs) on the outer shell layer of the nanocomposites. The extent of modulation depended on the separation distance between Ag NPs and upconversion nanocrystals. The optimum upconversion luminescence enhancement was observed at a separation distance of 10 nm for Ag NPs with two different sizes (15 and 30 nm). A maximum upconversion luminescence enhancement of 14.4-fold was observed when 15 nm Ag nanoparticles were used and 10.8-fold was observed when 30 nm Ag NPs were used. The separation distance dependent emission intensity is ascribed to the competition between energy

  18. Kyllinga brevifolia mediated greener silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Isa, Norain; Bakhari, Nor Aziyah; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

    2017-12-01

    Kyllinga brevifolia extract (KBE) was studied in this research as capping as well as reducing agent for the synthesis of greener plant mediated silver nanoparticles. This research was conducted in order to identify the compounds in the KBE that probable to work as reductant for the synthesis of Kyllinga brevifolia-mediated silver nanoparticles (AgNPs). Screening test such as Thin Layer Chromatography (TLC), Fourier Transform Infra-Red (FTIR), Carlo Erba Elemental analysis and Gas Chromatography-Mass Spectroscopy (GCMS) were used in identifying the natural compounds in KBE. The as-prepared AgNPs were characterized by UV-vis spectroscopy (UV-vis), Transmission Electron Microscope (TEM) and X-ray Diffraction (XRD). The TEM images showed that the as-synthesized silver have quasi-spherical particles are distributed uniformly with a narrow distribution from 5 nm to 40 nm. The XRD results demonstrated that the obtained AgNPs were face centre-cubic (FCC) structure. The catalytic activity of AgNPs on reduction of methylene blue (MB) using sodium borohydride (SB) was analyzed using UV-vis spectroscopy. This study showed that the efficacy of mediated AgNPs in catalysing the reduction of MB.

  19. Novel biosynthesis of Ag-hydroxyapatite: Structural and spectroscopic characterization

    NASA Astrophysics Data System (ADS)

    Ruíz-Baltazar, Álvaro de Jesús; Reyes-López, Simón Yobanny; Silva-Holguin, Pamela Nair; Larrañaga, Daniel; Estévez, Miriam; Pérez, Ramiro

    2018-06-01

    Silver-doped hydroxyapatite (Ag-HAP) was obtained by green synthesis route. The dopant silver nanoparticles (AgNPs) were obtained by biosynthesis based on Melissa officinalis extract. This research is focused on the characterization and the use of the nontoxic and environment-friendly Ag-HAP nanocomposite. The structural and morphological characterization of Ag-HAP nanocomposite was carried out by scanning electron microscopy (SEM), X-ray diffraction, Fourier-transform infrared (FT-IR) and Raman spectroscopy. The obtained nanoparticles exhibited a great interaction with the HAP matrix, performing an Ag-HAP nanocomposite. Changes in the structure of the Ag-HAP nanocomposite were corroborated by the different characterization techniques. Additionally, a homogeneous distribution of the AgNPs on the HAP structure was observed. The heterogeneous nucleation process employed to doping the HAP, offer a functional route to obtain a green composite with potentials applications in multiple fields, such as tissue engineering, bone repair as well as protein. These properties can be evaluated in subsequent studies.

  20. Silver nanoparticles induce endoplasmatic reticulum stress response in zebrafish

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Christen, Verena; Capelle, Martinus; Fent, Karl, E-mail: karl.fent@fhnw.ch

    2013-10-15

    Silver nanoparticles (AgNPs) find increasing applications, and therefore humans and the environment are increasingly exposed to them. However, potential toxicological implications are not sufficiently known. Here we investigate effects of AgNPs (average size 120 nm) on zebrafish in vitro and in vivo, and compare them to human hepatoma cells (Huh7). AgNPs are incorporated in zebrafish liver cells (ZFL) and Huh7, and in zebrafish embryos. In ZFL cells AgNPs lead to induction of reactive oxygen species (ROS), endoplasmatic reticulum (ER) stress response, and TNF-α. Transcriptional alterations also occur in pro-apoptotic genes p53 and Bax. The transcriptional profile differed in ZFL andmore » Huh7 cells. In ZFL cells, the ER stress marker BiP is induced, concomitant with the ER stress marker ATF-6 and spliced XBP-1 after 6 h and 24 h exposure to 0.5 g/L and 0.05 g/L AgNPs, respectively. This indicates the induction of different pathways of the ER stress response. Moreover, AgNPs induce TNF-α. In zebrafish embryos exposed to 0.01, 0.1, 1 and 5 mg/L AgNPs hatching was affected and morphological defects occurred at high concentrations. ER stress related gene transcripts BiP and Synv are significantly up-regulated after 24 h at 0.1 and 5 mg/L AgNPs. Furthermore, transcriptional alterations occurred in the pro-apoptotic genes Noxa and p21. The ER stress response was strong in ZFL cells and occurred in zebrafish embryos as well. Our data demonstrate for the first time that AgNPs lead to induction of ER stress in zebrafish. The induction of ER stress can have several consequences including the activation of apoptotic and inflammatory pathways. - Highlights: • Effects of silver nanoparticles (120 nm AgNPs) are investigated in zebrafish. • AgNPs induce all ER stress reponses in vitro in zebrafish liver cells. • AgNPs induce weak ER stress in zebrafish embryos. • AgNPs induce oxidative stress and transcripts of pro-apoptosis genes.« less

  1. Green synthesis and characterization of silver nanoparticles by leaf extracts of Cycas circinalis, Ficus amplissima, Commelina benghalensis and Lippia nodiflora

    NASA Astrophysics Data System (ADS)

    Johnson, I.; Prabu, H. Joy

    2015-01-01

    Biosynthesis of nanoparticles is a kind of bottom-up approach where the main reaction occurring is reduction. Since silver nanoparticles (AgNPs) have been used for infection prevention in medical field, it is more relevant to reduce their size using ancient Indian herbal plants. This method is good in anti-microbial efficiency against bacteria, viruses and other microorganisms and hence clearly enhances the medicinal usage of AgNPs. This type of green biosynthesis of nanoparticles has received increasing attention due to the growing need to develop safe, cost-effective and environmental-friendly technologies for nano-materials synthesis. In the process of synthesizing AgNPs, we observed a rapid reduction of silver ions leading to the formation of stable crystalline AgNPs in the solution. Plant extracts from Cycas circinalis, Ficus amplissima, Commelina benghalensis and Lippia nodiflora were used for the synthesis of AgNPs from silver nitrate solution. AgNPs were characterized by different techniques.

  2. Antibacterial and photocatalytic degradation efficacy of silver nanoparticles biosynthesized using Cordia dichotoma leaf extract

    NASA Astrophysics Data System (ADS)

    Mankamna Kumari, R.; Thapa, Nikita; Gupta, Nidhi; Kumar, Ajeet; Nimesh, Surendra

    2016-12-01

    The present study focuses on the biosynthesis of silver nanoparticles (AgNPs) along with its antibacterial and photocatalytic activity. The AgNPs were synthesized using Cordia dichotoma leaf extract and were characterized using UV-vis spectroscopy to determine the formation of AgNPs. FTIR was done to discern biomolecules responsible for reduction and capping of the synthesized nanoparticles. Further, DLS technique was performed to examine its hydrodynamic diameter, followed by SEM, TEM and XRD to determine its size, morphology and crystalline structure. Later, these AgNPs were studied for their potential role in antibacterial activity and photocatalytic degradation of azo dyes such as methylene blue and Congo red.

  3. Montmorillonite clay alters toxicity of silver nanoparticles in zebrafish (Danio rerio) eleutheroembryo.

    PubMed

    Gupta, Govind Sharan; Dhawan, Alok; Shanker, Rishi

    2016-11-01

    An exponential development in the use of silver nanoparticles (AgNPs) in consumer products has accelerated their release in aquatic environment. As the AgNPs enters into the aquatic systems, their fate may change due to interactions with abiotic (e.g. clay particles) or biotic factors. The abundantly present clay particles are expected to more prone for interaction with nanoparticles in aquatic systems. In the present study, it is demonstrated that AgNPs interacts with clay particles and forms heteroagglomerates. Furthermore, an impact on toxicity potential of AgNPs after interactions with clay particles was assessed by using zebrafish eleutheroembryos (72 h post hatching) as an in vivo model. The mortality rate of zebrafish eleutheroembryos was higher in case of exposure to AgNPs-clay complexes (pH 4.0 and 7.0) as compared to bare AgNPs. In addition, at earlier time points, the eleutheroembryos expressed higher levels of morphological changes in tail, yolk and pericardia, but the edema in yolk sac was followed by cell death. It can be concluded from the observations made in the present study that the inorganic colloids in the aquatic matrices can alter the fate and toxicity potential of nanoparticles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. In-site synthesis of monodisperse, oleylamine-capped Ag nanoparticles through microemulsion approach

    NASA Astrophysics Data System (ADS)

    Chen, Shun; Ju, Yanyun; Guo, Yi; Xiong, Chuanxi; Dong, Lijie

    2017-03-01

    Ag NPs were in-site synthesized through microemulsion method by reducing silver acetate with oleylamine-mediated at 70 °C with highly monodisperse and narrow size from 10 to 20 nm. The synthesis of Ag NPs was aided by oleylamine and the role of oleylamine was researched. This in-site synthesis approach to Ag NPs was reproducibility and high yield more than 80% with stable store about 6 months.

  5. Green synthesis of silver nanoparticles and investigation of their colorimetric sensing and cytotoxicity effects

    NASA Astrophysics Data System (ADS)

    Pahlavan Noghabi, Mohammad; Parizadeh, Mohammad Reza; Ghayour-Mobarhan, Majid; Taherzadeh, Danial; Hosseini, Hasan Ali; Darroudi, Majid

    2017-10-01

    The "Green" synthesis of metallic nanoparticles and investigation of their optical properties has become a useful application between nanoscience and medicine. In this work, silver nanoparticles (Ag-NPs) were successfully prepared through a facile and green method by treating silver ions with chitosan. Preparation of Ag-NPs in silver nitrate solution (0.01 M) resulted in small and spherical shapes of Ag-NPs with a mean diameter of 10.2 nm. The formation of Ag-NPs was approved by surface Plasmon resonance (SPR) absorption peaks, using UV-vis spectrophotometer, while Ag-NPs were successfully employed in colorimetric sensing of H2O2 via an analytical procedure. Degradation process of Ag-NPs, encouraged by the catalytic decomposition of H2O2, causes a significant change in the absorbance intensity of SPR band depending on the H2O2 concentration. The cytotoxicity effect of synthesized Ag-NPs was examined on HEK293 cell line. The results illustrate a concentration-dependent toxicity for the tested cells, while15.07 μg/mL of IC50 was obtained.

  6. Levofloxacin capped Ag-nanoparicles: A new highly selective sensor for cations under joint experimental and DFT investigation

    NASA Astrophysics Data System (ADS)

    Mondal Roy, Sutapa; Roy, Debesh Ranjan

    2017-05-01

    A very new and alternate function of an antibiotic drug levofloxacin (Lv), as a highly selective, colorimetric turn-OFF/turn-ON chemosensor for metal-ions Hg2+ and Fe3+, has been reported in this study. An extremely easy, very less time consuming, economical one-pot method of synthesis has been developed for the production of silver nanoparticles (AgNPs). The AgNPs that are stabilized and surface functionalized by Lv. Functionalization of AgNPs by antibiotic drug Lv has been thoroughly confirmed using FTIR spectrophotometry. Two carbonyl oxygen moieties, one belongs to the pyridine oxygen group and another one from the carboxylate oxygen group of Lv together form the binding site over the nanoparticle surface. The Lv-AgNPs system has shown naked eye detectable colour change, as well as significant change via both UV-Vis and fluorescence spectroscopy. The limits of detection (LODs) are predicted to be 6.86 × 10-8 M for Hg2+ and 2.52 × 10-9 M for Fe3+ using UV-Vis spectroscopy and 2.35 × 10-9 M for Fe3+ using fluorescence spectroscopy. UV-Vis spectroscopy, fluorescence spectroscopy, FTIR, TEM, DLS etc. have been used for the physico-chemical characterization of Lv-AgNPs system and the nanoparticle mediated sensing process. Detailed experimental and theoretical studies employing FTIR spectrophotometry and density functional theory (DFT) studies have been used for the elucidation of drug-nanoparticle based sensing mechanism. It is also demonstrated that the Lv-AgNPs system can show real time application using Test-Paper Kit to establish the drug-nanoparticle assembly as a potential colorimetric turn-OFF/turn-ON sensing system for Hg2+ and Fe3+ respectively.

  7. Effects of Humic and Fulvic Acids on Silver Nanoparticle Stability, Dissolution, and Toxicity

    PubMed Central

    Gunsolus, Ian L.; Mousavi, Maral P. S.; Hussein, Kadir; Bühlmann, Philippe; Haynes, Christy L.

    2015-01-01

    The colloidal stability of silver nanoparticles (AgNPs) in natural aquatic environments influences their transport and environmental persistence, while their dissolution to Ag+ influences their toxicity to organisms. Here, we characterize the colloidal stability, dissolution behavior, and toxicity of two industrially relevant classes of AgNPs (i.e., AgNPs stabilized by citrate or polyvinylpyrrolidone) after exposure to natural organic matter (NOM, i.e., Suwannee River Humic and Fulvic Acid Standards and Pony Lake Fulvic Acid Reference). We show that NOM interaction with the nanoparticle surface depends on (i) the NOM’s chemical composition, where sulfur- and nitrogen-rich NOM more significantly increases colloidal stability, and (ii) the affinity of the capping agent for the AgNP surface, where nanoparticles with loosely bound capping agents are more effectively stabilized by NOM. Adsorption of NOM is shown to have little effect on AgNP dissolution under most experimental conditions, the exception being when the NOM is rich in sulfur and nitrogen. Similarly, the toxicity of AgNPs to a bacterial model (Shewanella oneidensis MR-1) decreases most significantly in the presence of sulfur- and nitrogen-rich NOM. Our data suggest that the rate of AgNP aggregation and dissolution in aquatic environments containing NOM will depend on the chemical composition of the NOM, and that the toxicity of AgNPs to aquatic microorganisms is controlled primarily by the extent of nanoparticle dissolution. PMID:26047330

  8. Ultra-low temperature sintering of Cu@Ag core-shell nanoparticle paste by ultrasonic in air for high-temperature power device packaging.

    PubMed

    Ji, Hongjun; Zhou, Junbo; Liang, Meng; Lu, Huajun; Li, Mingyu

    2018-03-01

    Sintering of low-cost Cu nanoparticles (NPs) for interconnection of chips to substrate at low temperature and in atmosphere conditions is difficult because they are prone to oxidation, but dramatically required in semiconductor industry. In the present work, we successfully synthesized Cu@Ag NPs paste, and they were successfully applied for joining Cu/Cu@Ag NPs paste/Cu firstly in air by the ultrasonic-assisted sintering (UAS) at a temperature of as low as 160 °C. Their sintered microstructures featuring with dense and crystallized cells are completely different from the traditional thermo-compression sintering (TCS). The optimized shear strength of the joints reached to 54.27 MPa, exhibiting one order of magnitude higher than TCS at the same temperature (180 °C) under the UAS. This ultra-low sintering temperature and high performance of the sintered joints were ascribed to ultrasonic effects. The ultrasonic vibrations have distinct effects on the metallurgical reactions of the joints, resulting in the contact and growth of Cu core and the stripping and connection of Ag shell, which contributes to the high shear strength. Thus, the UAS of Cu@Ag NPs paste has a great potential to be applied for high-temperature power device packaging. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Toxicological studies on silver nanoparticles: challenges and opportunities in assessment, monitoring and imaging

    PubMed Central

    Stensberg, Matthew Charles; Wei, Qingshan; McLamore, Eric Scott; Porterfield, David Marshall; Wei, Alexander; Sepúlveda, Marĺa Soledad

    2012-01-01

    Silver nanoparticles (Ag NPs) are becoming increasingly prevalent in consumer products as antibacterial agents. The increased use of Ag NP-enhanced products may lead to an increase in toxic levels of environmental silver, but regulatory control over the use or disposal of such products is lagging due to insufficient assessment on the toxicology of Ag NPs and their rate of release into the environment. In this article we discuss recent research on the transport, activity and fate of Ag NPs at the cellular and organismic level, in conjunction with traditional and recently established methods of nanoparticle characterization. We include several proposed mechanisms of cytotoxicity based on such studies, as well as new opportunities for investigating the uptake and fate of Ag NPs in living systems. PMID:21793678

  10. Electrostatic Assemblies of Well-Dispersed AgNPs on the Surface of Electrospun Nanofibers as Highly Active SERS Substrates for Wide-Range pH Sensing.

    PubMed

    Yang, Tong; Ma, Jun; Zhen, Shu Jun; Huang, Cheng Zhi

    2016-06-15

    Surface-enhanced Raman scattering (SERS) has shown high promise in analysis and bioanalysis, wherein noble metal nanoparticles (NMNPs) such as silver nanoparticles were employed as substrates because of their strong localized surface plasmon resonance (LSPR) properties. However, SERS-based pH sensing was restricted because of the aggregation of NMNPs in acidic medium or biosamples with high ionic strength. Herein, by using the electrostatic interaction as a driving force, AgNPs are assembled on the surface of ethylene imine polymer (PEI)/poly(vinyl alcohol) (PVA) electrospun nanofibers, which are then applied as highly sensitive and reproducible SERS substrate with an enhancement factor (EF) of 10(7)-10(8). When p-aminothiophenol (p-ATP) is used as an indicator with its b2 mode, a good and wide linear response to pH ranging from 2.56 to 11.20 could be available, and the as-prepared nanocomposite fibers then could be fabricated as excellent pH sensors in complicated biological samples such as urine, considering that the pH of urine could reflect the acid-base status of a person. This work not only emerges a cost-effective, direct, and convenient approach to homogeneously decorate AgNPs on the surface of polymer nanofibers but also supplies a route for preparing other noble metal nanofibrous sensing membranes.

  11. Biosynthesis of silver nanoparticles from Cavendish banana peel extract and its antibacterial and free radical scavenging assay: a novel biological approach

    NASA Astrophysics Data System (ADS)

    Kokila, T.; Ramesh, P. S.; Geetha, D.

    2015-12-01

    Biosynthesis of metallic silver nanoparticles has now become an alternative to physical and chemical approaches. In the present study, silver nanoparticles (AgNPs) were synthesized from Cavendish banana peel extract (CBPE) and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Atomic force microscopy (AFM), Field emission scanning electronic microscope (FESEM), Dynamic light scattering (DLS) and zeta potential (ZP). The AgNPs formation was confirmed by UV-visible spectroscopy through color conversion due to surface plasma resonance band at 430 nm. The effect of pH on nanoparticle synthesis was determined by adjusting the various pH of the reaction mixtures. The crystalline nature of nanoparticles was confirmed from the XRD pattern, and the grain size was found to be around 34 nm. To identify the compounds responsible for the bioreduction of Ag+ ion and the stabilization of AgNPs produced, the functional group present in Cavendish banana peel extract was investigated using FTIR. AFM has proved to be very helpful in determining morphological features and the diameter of AgNPs in the range of 23-30 nm was confirmed by FESEM. DLS studies revealed that the average size of AgNPs was found to be around 297 nm. Zeta potential value for AgNPs obtained was -11 mV indicating the moderate stability of synthesized nanoparticles. The antibacterial activity of the nanoparticles was studied against Gram-positive and Gram-negative bacteria. Biosynthesized AgNPs showed a strong DPPH radical and ABTS scavengers compared to the aqueous peel extract of Cavendish banana.

  12. Evaluation of cytotoxicity, immune compatibility and antibacterial activity of biogenic silver nanoparticles.

    PubMed

    Składanowski, M; Golinska, P; Rudnicka, K; Dahm, H; Rai, M

    2016-12-01

    The study was focused on assessment of antibacterial activity, cytotoxicity and immune compatibility of biogenic silver nanoparticles (AgNPs) synthesized from Streptomyces sp. NH28 strain. Nanoparticles were biosynthesized and characterized by UV-Vis spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, nanoparticle tracking analysis system and zeta potential. Antibacterial activity was tested against Gram-positive and Gram-negative bacteria; minimal inhibitory concentration was recorded. Cytotoxicity was estimated using L929 mouse fibroblasts via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. Biocompatibility of AgNPs was performed using THP1-XBlue™ cells. Biogenic AgNPs presented high antibacterial activity against all tested bacteria. Minimum inhibitory concentration of AgNPs against bacterial cells was found to be in range of 1.25-10 μg/mL. Silver nanoparticles did not show any harmful interaction to mouse fibroblast cell line, and no activation of nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) cells was observed at concentration below 10 µg/mL. The half-maximal inhibitory concentration (IC 50 ) value was established at 64.5 μg/mL. Biological synthesis of silver can be used as an effective system for formation of metal nanoparticles. Biosynthesized AgNPs can be used as an antibacterial agent, which can be safe for eukaryotic cells.

  13. Enhanced Raman scattering of graphene by silver nanoparticles with different densities and locations

    NASA Astrophysics Data System (ADS)

    Sun, Hai-Bin; Fu, Can; Xia, Yan-Jie; Zhang, Chong-Wu; Du, Jiang-Hui; Yang, Wen-Chao; Guo, Peng-Fei; Xu, Jun-Qi; Wang, Chun-Lei; Jia, Yong-Lei; Liu, Jiang-Feng

    2017-02-01

    Graphene-metal nanoparticle heterojunctions greatly improve the surface-enhanced Raman scattering (SERS) by strong light-graphene interactions. In this work, to enhance the Raman scattering, Ag nanoparticles (NPs) underneath and on top of the graphene were used. Then, Raman scattering of graphene is significantly enhanced approximately 67-fold, and the enhancement factor of the graphene G peak increases with the Ag NP density at the same location. In addition, an obvious red-shift and broadening of the resonance peak of Ag NPs is presented, which may be correlated to the strength of Raman enhancement, the coupling of the deposited Ag NPs and the graphene. Further, graphene-Ag NP heterojunctions can be used as SERS substrates to obtain the strongest Raman signals of the rhodamine (R6G) molecules and the weakest photoluminescence (PL) background from the Ag NPs. Based on the tunable Raman enhancement, graphene-Ag NPs offer a promising platform for engineering SERS substrates to obtain highly sensitive detection of trace levels of analyte molecules.

  14. Antimicrobial, Antioxidant and Cytotoxic Activity of Silver Nanoparticles Synthesized by Leaf Extract of Erythrina suberosa (Roxb.).

    PubMed

    Mohanta, Yugal K; Panda, Sujogya K; Jayabalan, Rasu; Sharma, Nanaocha; Bastia, Akshaya K; Mohanta, Tapan K

    2017-01-01

    In this experiment, biosynthesized silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Erythrina suberosa (Roxb.). The biosynthesis of silver nanoparticle was continuously followed by UV-vis spectrophotometric analysis. The response of the phytoconstituents resides in E. suberusa during synthesis of stable AgNPs were analyzed by ATR- fourier-transform infrared spectroscopy. Further, the size, charge, and polydispersity nature of AgNPs were studied using dynamic light scattering spectroscopy. The morphology of the nanoparticles was determined by scanning electron microscopy. Current result shows core involvement of plant extracts containing glycosides, flavonoids, and phenolic compounds played a crucial role in the biosynthesis of AgNPs. The antimicrobial activities of silver nanoparticles were evaluated against different pathogenic bacterium and fungi. The antioxidant property was studied by radical scavenging (DPPH) assay and cytotoxic activity was evaluated against A-431 osteosarcoma cell line by MTT assay. The characteristics of the synthesized silver nanoparticles suggest their application as a potential antimicrobial and anticancer agent.

  15. Antimicrobial, Antioxidant and Cytotoxic Activity of Silver Nanoparticles Synthesized by Leaf Extract of Erythrina suberosa (Roxb.)

    PubMed Central

    Mohanta, Yugal K.; Panda, Sujogya K.; Jayabalan, Rasu; Sharma, Nanaocha; Bastia, Akshaya K.; Mohanta, Tapan K.

    2017-01-01

    In this experiment, biosynthesized silver nanoparticles (AgNPs) were synthesized using aqueous leaf extract of Erythrina suberosa (Roxb.). The biosynthesis of silver nanoparticle was continuously followed by UV-vis spectrophotometric analysis. The response of the phytoconstituents resides in E. suberusa during synthesis of stable AgNPs were analyzed by ATR- fourier-transform infrared spectroscopy. Further, the size, charge, and polydispersity nature of AgNPs were studied using dynamic light scattering spectroscopy. The morphology of the nanoparticles was determined by scanning electron microscopy. Current result shows core involvement of plant extracts containing glycosides, flavonoids, and phenolic compounds played a crucial role in the biosynthesis of AgNPs. The antimicrobial activities of silver nanoparticles were evaluated against different pathogenic bacterium and fungi. The antioxidant property was studied by radical scavenging (DPPH) assay and cytotoxic activity was evaluated against A-431 osteosarcoma cell line by MTT assay. The characteristics of the synthesized silver nanoparticles suggest their application as a potential antimicrobial and anticancer agent. PMID:28367437

  16. Metallic nanoparticles reduce the migration of human fibroblasts in vitro.

    PubMed

    Vieira, Larissa Fernanda de Araújo; Lins, Marvin Paulo; Viana, Iana Mayane Mendes Nicácio; Dos Santos, Jeniffer Estevão; Smaniotto, Salete; Reis, Maria Danielma Dos Santos

    2017-12-01

    Nanoparticles have extremely wide applications in the medical and biological fields. They are being used in biosensors, local drug delivery, diagnostics, and medical therapy. However, the potential effects of nanoparticles on target cell and tissue function, apart from cytotoxicity, are not completely understood. Thus, the aim of this study was to investigate the in vitro effects of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) on human fibroblasts with respect to their interaction with the extracellular matrix and in cell migration. Immunofluorescence analysis revealed that treatment with AgNPs or AuNPs decreased collagen and laminin production at all the concentrations tested (0.1, 1, and 10 μg/mL). Furthermore, cytofluorometric analysis showed that treatment with AgNPs reduced the percentage of cells expressing the collagen receptor very late antigen 2, α 2 β 1 integrin (VLA-2) and the laminin receptor very late antigen 6, α 6 β 1 integrin (VLA-6). In contrast, AuNP treatment increased and decreased the percentages of VLA-2-positive and VLA-6-positive cells, respectively, as compared to the findings for the controls. Analysis of cytoskeletal reorganization showed that treatment with both types of nanoparticles increased the formation of stress fibres and number of cell protrusions and impaired cell polarity. Fibroblasts exposed to different concentrations of AuNPs and AgNPs showed reduced migration through transwell chambers in the functional chemotaxis assay. These results demonstrated that metal nanoparticles may influence fibroblast function by negatively modulating the deposition of extracellular matrix molecules (ECM) and altering the expression of ECM receptors, cytoskeletal reorganization, and cell migration.

  17. Metallic nanoparticles reduce the migration of human fibroblasts in vitro

    NASA Astrophysics Data System (ADS)

    Vieira, Larissa Fernanda de Araújo; Lins, Marvin Paulo; Viana, Iana Mayane Mendes Nicácio; dos Santos, Jeniffer Estevão; Smaniotto, Salete; Reis, Maria Danielma dos Santos

    2017-03-01

    Nanoparticles have extremely wide applications in the medical and biological fields. They are being used in biosensors, local drug delivery, diagnostics, and medical therapy. However, the potential effects of nanoparticles on target cell and tissue function, apart from cytotoxicity, are not completely understood. Thus, the aim of this study was to investigate the in vitro effects of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) on human fibroblasts with respect to their interaction with the extracellular matrix and in cell migration. Immunofluorescence analysis revealed that treatment with AgNPs or AuNPs decreased collagen and laminin production at all the concentrations tested (0.1, 1, and 10 μg/mL). Furthermore, cytofluorometric analysis showed that treatment with AgNPs reduced the percentage of cells expressing the collagen receptor very late antigen 2, α2β1 integrin (VLA-2) and the laminin receptor very late antigen 6, α6β1 integrin (VLA-6). In contrast, AuNP treatment increased and decreased the percentages of VLA-2-positive and VLA-6-positive cells, respectively, as compared to the findings for the controls. Analysis of cytoskeletal reorganization showed that treatment with both types of nanoparticles increased the formation of stress fibres and number of cell protrusions and impaired cell polarity. Fibroblasts exposed to different concentrations of AuNPs and AgNPs showed reduced migration through transwell chambers in the functional chemotaxis assay. These results demonstrated that metal nanoparticles may influence fibroblast function by negatively modulating the deposition of extracellular matrix molecules (ECM) and altering the expression of ECM receptors, cytoskeletal reorganization, and cell migration.

  18. Ferritin-mediated biomimetic synthesis of bimetallic Au-Ag nanoparticles on graphene nanosheets for electrochemical detection of hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Wang, Li; Wang, Jiku; Ni, Pengjuan; Li, Zhuang

    2015-03-01

    We demonstrated a biomimetic green synthesis of bimetallic Au-Ag nanoparticles (NPs) on graphene nanosheets (GNs). The spherical protein, ferritin (Fr), was bound onto GNs and served as the template for the synthesis of GN/Au-Ag nanohybrids. The created GN/Au-Ag nanohybrids were further utilized to fabricate a non-enzymatic amperometric biosensor for the sensitive detection of hydrogen peroxide (H2O2), and this biosensor displayed high performances to determine H2O2 with a detection limit of 20.0 × 10-6 M and a linear detection range from 2.0 μM to 7.0 mM.

  19. Synthesis and antibacterial activity of water-dispersible silver nanoparticles via micellar nanoreactors

    NASA Astrophysics Data System (ADS)

    Pofali, Prasad; Shirolikar, Seema; Borde, Lalit; Pattani, Aditya; Dandekar, Prajakta; Jain, Ratnesh

    2018-04-01

    We have synthesized silver nanoparticles (AgNPs) using micelles of sugar fatty acid ester by dissolving the surfactant in a mixture of iso-octane and n-butanol, with solid-liquid extraction. Highly concentrated, water-dispersible AgNPs were obtained after thorough washing with alcohol, to remove excess of sucrose fatty acid ester DK SS and salt, followed by drying. The particles were characterized for their size, morphology and crystallinity using UV-Visible spectrophotometry, Transmission Electron Microscopy and x-ray diffractometry. Antibacterial study, confirmed the activity of nanoparticles against E. coli, P. aeruginosa and S. aureus, which causes diseases including diarrhoea and several life-threatening infections. Antibacterial activity of E. coli and P. aeruginosa was found to be 2.5 fold and for S. aureus 1.6 fold compared to 50 ppm conc. of Silver Nitrate. Our method of producing nanoparticles is employed as a platform technology for synthesizing other inorganic nanoparticles. This is the first report discussing the use of micellar carriers for obtaining silver nanopowder, to the best of our knowledge, which has the potential to overcome limitations during fabrication of AgNPs using reverse/inverse micelles. Our method yielded nano-sized, water-dispersible AgNPs via an easy and economic approach. The one-pot approach possesses advantages in terms of cost and simplicity, as compared with traditional methods of producing powdered AgNPs using energy intensive and expensive techniques like lyophilisation. The developed method, thus, possesses immense potential for commercial synthesis of AgNPs.

  20. Ag Nanoparticles-Modified 3D Graphene Foam for Binder-Free Electrodes of Electrochemical Sensors.

    PubMed

    Han, Tao; Jin, Jianli; Wang, Congxu; Sun, Youyi; Zhang, Yinghe; Liu, Yaqing

    2017-02-16

    Ag nanoparticles-modified 3D graphene foam was synthesized through a one-step in-situ approach and then directly applied as the electrode of an electrochemical sensor. The composite foam electrode exhibited electrocatalytic activity towards Hg(II) oxidation with high limit of detection and sensitivity of 0.11 μM and 8.0 μA/μM, respectively. Moreover, the composite foam electrode for the sensor exhibited high cycling stability, long-term durability and reproducibility. These results were attributed to the unique porous structure of the composite foam electrode, which enabled the surface of Ag nanoparticles modified reduced graphene oxide (Ag NPs modified rGO) foam to become highly accessible to the metal ion and provided more void volume for the reaction with metal ion. This work not only proved that the composite foam has great potential application in heavy metal ions sensors, but also provided a facile method of gram scale synthesis 3D electrode materials based on rGO foam and other electrical active materials for various applications.

  1. Ag Nanoparticles-Modified 3D Graphene Foam for Binder-Free Electrodes of Electrochemical Sensors

    PubMed Central

    Han, Tao; Jin, Jianli; Wang, Congxu; Sun, Youyi; Zhang, Yinghe; Liu, Yaqing

    2017-01-01

    Ag nanoparticles-modified 3D graphene foam was synthesized through a one-step in-situ approach and then directly applied as the electrode of an electrochemical sensor. The composite foam electrode exhibited electrocatalytic activity towards Hg(II) oxidation with high limit of detection and sensitivity of 0.11 µM and 8.0 µA/µM, respectively. Moreover, the composite foam electrode for the sensor exhibited high cycling stability, long-term durability and reproducibility. These results were attributed to the unique porous structure of the composite foam electrode, which enabled the surface of Ag nanoparticles modified reduced graphene oxide (Ag NPs modified rGO) foam to become highly accessible to the metal ion and provided more void volume for the reaction with metal ion. This work not only proved that the composite foam has great potential application in heavy metal ions sensors, but also provided a facile method of gram scale synthesis 3D electrode materials based on rGO foam and other electrical active materials for various applications. PMID:28336878

  2. Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles

    PubMed Central

    Jeong, Lim; Park, Won Ho

    2014-01-01

    Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag+ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO3)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO3/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO3 and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO3. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM). PMID:24758929

  3. Characterization, Antibacterial and Antioxidant Properties of Silver Nanoparticles Synthesized from Aqueous Extracts of Allium sativum, Zingiber officinale, and Capsicum frutescens

    PubMed Central

    Otunola, Gloria Aderonke; Afolayan, Anthony Jide; Ajayi, Emmanuel Olusegun; Odeyemi, Samuel Wale

    2017-01-01

    Background: Herbal drug delivery is limited by poor solubility and bioavailability which can be overcome with suitable nanomaterials that will enhance their pharmacokinetics and performance. Objective: This study aimed to analyze the synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from three spices. Materials and Methods: AgNPs were prepared using 0.1 M silver nitrate and aqueous extracts of Allium sativum L. (garlic), Zingiber officinale Rosc. (ginger), and Capsicum frutescens L. (cayenne pepper). The AgNPs were characterized using ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. Results: The AgNPs were formed within an hour of the reaction and showed maximum UV-Vis absorption in the 375–480 nm range. SEM and TEM revealed well-dispersed spherical particles with little agglomeration, average sizes of 3–6 nm, 3–22 nm, and 3–18 nm for garlic, ginger, and cayenne pepper, respectively. FTIR showed that amine, protein, phenolic, aromatic, and alkynes groups contributed to AgNP synthesis and XRD confirmed their crystalline and face-centered cubic nature. Antibacterial action of the AgNPs was in the following order: ginger (minimum inhibitory concentration [MIC] <25 μg/mL) > garlic> cayenne pepper (MIC 125 μg/mL). Antioxidant action showed cayenne pepper > ginger > garlic (inhibitory concentration 50% [IC50]: 40, 240, and 250 μg/mL, respectively) against 2,2-Azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and garlic > cayenne pepper > ginger (IC50: <31.25, 40, and 120 μg/mL, respectively) against 1,1-diphenyl-2-picrylhydrazyl. Conclusion: Optimization of this green synthesis would support the production of AgNPs with great therapeutic potentials. SUMMARY The synthesis, characterization, and biological activities of silver nanoparticles (AgNPs) from

  4. Silver Nanoparticles Entering Soils via the Wastewater-Sludge-Soil Pathway Pose Low Risk to Plants but Elevated Cl Concentrations Increase Ag Bioavailability.

    PubMed

    Wang, Peng; Menzies, Neal W; Dennis, Paul G; Guo, Jianhua; Forstner, Christian; Sekine, Ryo; Lombi, Enzo; Kappen, Peter; Bertsch, Paul M; Kopittke, Peter M

    2016-08-02

    The widespread use of silver nanoparticles (Ag-NPs) results in their movement into wastewater treatment facilities and subsequently to agricultural soils via application of contaminated sludge. On-route, the chemical properties of Ag may change, and further alterations are possible upon entry to soil. In the present study, we examined the long-term stability and (bio)availability of Ag along the "wastewater-sludge-soil" pathway. Synchrotron-based X-ray absorption spectroscopy (XAS) revealed that ca. 99% of Ag added to the sludge reactors as either Ag-NPs or AgNO3 was retained in sludge, with ≥79% of this being transformed to Ag2S, with the majority (≥87%) remaining in this form even after introduction to soils at various pH values and Cl concentrations for up to 400 days. Diffusive gradients in thin films (DGT), chemical extraction, and plant uptake experiments indicated that the potential (bio)availability of Ag in soil was low but increased markedly in soils with elevated Cl, likely due to the formation of soluble AgClx complexes in the soil solution. Although high Cl concentrations increased the bioavailability of Ag markedly, plant growth was not reduced in any treatment. Our results indicate that Ag-NPs entering soils through the wastewater-sludge-soil pathway pose low risk to plants due to their conversion to Ag2S in the wastewater treatment process, although bioavailability may increase in saline soils or when irrigated with high-Cl water.

  5. Nanoparticle-nanoparticle vs. nanoparticle-substrate hot spot contributions to the SERS signal: studying Raman labelled monomers, dimers and trimers.

    PubMed

    Sergiienko, Sergii; Moor, Kamila; Gudun, Kristina; Yelemessova, Zarina; Bukasov, Rostislav

    2017-02-08

    We used a combination of Raman microscopy, AFM and TEM to quantify the influence of dimerization on the surface enhanced Raman spectroscopy (SERS) signal for gold and silver nanoparticles (NPs) modified with Raman reporters and situated on gold, silver, and aluminum films and a silicon wafer. The overall increases in the mean SERS enhancement factor (EF) upon dimerization (up by 43% on average) and trimerisation (up by 96% on average) of AuNPs and AgNPs on the studied metal films are within a factor of two, which is moderate when compared to most theoretical models. However, the maximum ratio of EFs for some dimers to the mean EF of monomers can be as high as 5.5 for AgNPs on a gold substrate. In contrast, for dimerization and trimerization of gold and silver NPs on silicon, the mean EF increases by 1-2 orders of magnitude relative to the mean EF of single NPs. Therefore, hot spots in the interparticle gap between gold nanoparticles rather than hot spots between Au nanoparticles and the substrate dominate SERS enhancement for dimers and trimers on a silicon substrate. However, Raman labeled noble metal nanoparticles on plasmonic metal films generate on average SERS enhancement of the same order of magnitude for both types of hot spot zones (e.g. NP/NP and NP/metal film).

  6. Electrochemical synthesis, characterisation and phytogenic properties of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Singaravelan, R.; Bangaru Sudarsan Alwar, S.

    2015-12-01

    This work exemplifies a simple and rapid method for the synthesis of silver nanodendrite with a novel electrochemical technique. The antibacterial activity of these silver nanoparticles (Ag NPs) against pathogenic bacteria was investigated along with the routine study of optical and spectral characterisation. The optical properties of the silver nanoparticles were characterised by diffuse reflectance spectroscopy. The optical band gap energy of the electrodeposited Ag NPs was determined from the diffuse reflectance using Kubelka-Munk formula. X-ray diffraction (XRD) studies were carried out to determine the crystalline nature of the silver nanoparticles which confirmed the formation of silver nanocrystals. The XRD pattern revealed that the electrodeposited Ag NPs were in the cubic geometry with dendrite preponderance. The average particle size and the peak broadening were deliberated using Debye-Scherrer equation and lattice strain due to the peak broadening was studied using Williamson-Hall method. Surface morphology of the Ag NPs was characterised by high-resolution scanning electron microscope and the results showed the high degree of aggregation in the particles. The antibacterial activity of the Ag NPs was evaluated and showed unprecedented level antibacterial activity against multidrug resistant strains such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia and Escherichia coli in combination with Streptomycin.

  7. Green synthesis of silver nanoparticles from Moringa oleifera leaf extracts and its antimicrobial potential

    NASA Astrophysics Data System (ADS)

    Moodley, Jerushka S.; Babu Naidu Krishna, Suresh; Pillay, Karen; Sershen; Govender, Patrick

    2018-03-01

    In this study we report on the synthesis of silver nanoparticles (AgNPs) from the leaf extracts of Moringa oleifera using sunlight irradiation as primary source of energy, and its antimicrobial potential. Silver nanoparticle formation was confirmed by surface plasmon resonance at 450 nm and 440 nm, respectively for both fresh and freeze-dried leaf samples. Crystanality of AgNPs was confirmed by transmission electron microscopy, scanning electron microscopy with energy dispersive x-ray spectroscopy and Fourier transform infrared (FTIR) spectroscopy analysis. FTIR spectroscopic analysis suggested that flavones, terpenoids and polysaccharides predominate and are primarily responsible for the reduction and subsequent capping of AgNPs. X-ray diffraction analysis also demonstrated that the size range of AgNPs from both samples exhibited average diameters of 9 and 11 nm, respectively. Silver nanoparticles showed antimicrobial activity on both bacterial and fungal strains. The biosynthesised nanoparticle preparations from M. oleifera leaf extracts exhibit potential for application as broad-spectrum antimicrobial agents.

  8. Synthesis of silver nanoparticles from two acidophilic strains of Pilimelia columellifera subsp. pallida and their antibacterial activities.

    PubMed

    Golińska, Patrycja; Wypij, Magdalena; Rathod, Dnyaneshwar; Tikar, Sagar; Dahm, Hanna; Rai, Mahendra

    2016-05-01

    Biosynthesis of silver nanoparticles (AgNPs) is an eco-friendly approach by using different biological sources; for example, plants and microorganisms such as bacteria, fungi, and actinobacteria. In this report, we present the biological synthesis of silver nanoparticles (AgNPs) by acidophilic actinomycetes SL19 and SL24 strains isolated from pine forest soil (pH < 4.0). The isolates based on 16S rRNA gene sequence were identified as Pilimelia columellifera subsp. pallida. The synthesized AgNPs were characterized by visual observations of colour change from light-yellow to dark-brown. The UV-vis spectra of AgNPs were recorded at 425 and 430 nm. The AgNPs were further characterized by Nanoparticle tracking analysis (NTA), Zeta potential, Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM). FTIR analysis revealed the presence of proteins as a capping agent. TEM analysis confirmed the formation of spherical and polydispersed NPs of 12.7 and 15.9 nm sizes. The in vitro antibacterial activity of AgNPs alone and in combination with antibiotics was evaluated against clinical bacteria viz., Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and uropathogens such as Enterobacter, S. aureus, P. aeruginosa, K. pneumoniae, and E. coli. The lowest MIC (40 μg ml(-1) ) was demonstrated by AgNPs synthesized from SL24 against E. coli. However, the AgNPs of SL19 showed lowest MIC (70 μg ml(-1) ) against S. aureus. The activity of antibiotic was enhanced, when tested in combination with silver nanoparticles synthesized from both actinobacterial strains. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Applications of plant terpenoids in the synthesis of colloidal silver nanoparticles.

    PubMed

    Mashwani, Zia-Ur-Rehman; Khan, Mubarak Ali; Khan, Tariq; Nadhman, Akhtar

    2016-08-01

    Green chemistry is the design of chemical products and processes that reduce or eliminate the generation of hazardous substances. Since the last few years, natural products especially plant secondary metabolites have been extensively explored for their potency to synthesize silver nanoparticles (AgNPs). The plant-based AgNPs are safer, energy efficient, eco-friendly, and less toxic than chemically synthesized counterparts. The secondary metabolites, ubiquitously found in plants especially the terpenoid-rich essential oils, have a significant role in AgNPs synthesis. Terpenoids belong to the largest family of natural products and are found in all kinds of organisms. Their involvement in the synthesis of plant-based AgNPs has got much attention in the recent years. The current article is not meant to provide an exhaustive overview of green synthesis of nanoparticles, but to present the pertinent role of plant terpenoids in the biosynthesis of AgNPs, as capping and reducing agents for development of uniform size and shape AgNPs. An emphasis on the important role of FTIR in the identification and elucidation of major functional groups in terpenoids for AgNPs synthesis has also been reviewed in this manuscript. It was found that no such article is available that has discussed the role of plant terpenoids in the green synthesis of AgNPs. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Elucidating Protein Involvement in the Stabilization of the Biogenic Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ballottin, Daniela; Fulaz, Stephanie; Souza, Michele L.; Corio, Paola; Rodrigues, Alexandre G.; Souza, Ana O.; Gaspari, Priscyla M.; Gomes, Alexandre F.; Gozzo, Fábio; Tasic, Ljubica

    2016-06-01

    Silver nanoparticles (AgNPs) have been broadly used as antibacterial and antiviral agents. Further, interests for green AgNP synthesis have increased in recent years and several results for AgNP biological synthesis have been reported using bacteria, fungi and plant extracts. The understanding of the role and nature of fungal proteins, their interaction with AgNPs and the subsequent stabilization of nanosilver is yet to be deeply investigated. Therefore, in an attempt to better understand biogenic AgNP stabilization with the extracellular fungal proteins and to describe these supramolecular interactions between proteins and silver nanoparticles, AgNPs, produced extracellularly by Aspergillus tubingensis—isolated as an endophytic fungus from Rizophora mangle—were characterized in order to study their physical characteristics, identify the involved proteins, and shed light into the interactions among protein-NPs by several techniques. AgNPs of around 35 nm in diameter as measured by TEM and a positive zeta potential of +8.48 mV were obtained. These AgNPs exhibited a surface plasmon resonance (SPR) band at 440 nm, indicating the nanoparticles formation, and another band at 280 nm, attributed to the electronic excitations in tryptophan, tyrosine, and/or phenylalanine residues in fungal proteins. Fungal proteins were covalently bounded to the AgNPs, mainly through S-Ag bonds due to cysteine residues (HS-) and with few N-Ag bonds from H2N- groups, as verified by Raman spectroscopy. Observed supramolecular interactions also occur by electrostatic and other protein-protein interactions. Furthermore, proteins that remain free on AgNP surface may perform hydrogen bonds with other proteins or water increasing thus the capping layer around the AgNPs and consequently expanding the hydrodynamic diameter of the particles (~264 nm, measured by DLS). FTIR results enabled us to state that proteins adsorbed to the AgNPs did not suffer relevant secondary structure alteration upon

  11. Fate of zinc and silver engineered nanoparticles in sewerage networks.

    PubMed

    Brunetti, Gianluca; Donner, Erica; Laera, Giuseppe; Sekine, Ryo; Scheckel, Kirk G; Khaksar, Maryam; Vasilev, Krasimir; De Mastro, Giuseppe; Lombi, Enzo

    2015-06-15

    Engineered zinc oxide (ZnO) and silver (Ag) nanoparticles (NPs) used in consumer products are largely released into the environment through the wastewater stream. Limited information is available regarding the transformations they undergo during their transit through sewerage systems before reaching wastewater treatment plants. To address this knowledge gap, laboratory-scale systems fed with raw wastewater were used to evaluate the transformation of ZnO- and Ag-NPs within sewerage transfer networks. Two experimental systems were established and spiked with either Ag- and ZnO-NPs or with their dissolved salts, and the wastewater influent and effluent samples from both systems were thoroughly characterised. X-ray absorption spectroscopy (XAS) was used to assess the extent of the chemical transformation of both forms of Zn and Ag during transport through the model systems. The results indicated that both ZnO- and Ag-NPs underwent significant transformation during their transport through the sewerage network. Reduced sulphur species represented the most important endpoint for these NPs in the sewer with slight differences in terms of speciation; ZnO converted largely to Zn sulfide, while Ag was also sorbed to cysteine and histidine. Importantly, both ionic Ag and Ag-NPs formed secondary Ag sulfide nanoparticles in the sewerage network as revealed by TEM analysis. Ag-cysteine was also shown to be a major species in biofilms. These results were verified in the field using recently developed nanoparticle in situ deployment devices (nIDDs) which were exposed directly to sewerage network conditions by immersing them into a municipal wastewater network trunk sewer and then retrieving them for XAS analysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Plasmon enhanced water splitting mediated by hybrid bimetallic Au-Ag core-shell nanostructures.

    PubMed

    Erwin, William R; Coppola, Andrew; Zarick, Holly F; Arora, Poorva; Miller, Kevin J; Bardhan, Rizia

    2014-11-07

    In this work, we employed wet chemically synthesized bimetallic Au-Ag core-shell nanostructures (Au-AgNSs) to enhance the photocurrent density of mesoporous TiO2 for water splitting and we compared the results with monometallic Au nanoparticles (AuNPs). While Au-AgNSs incorporated photoanodes give rise to 14× enhancement in incident photon to charge carrier efficiency, AuNPs embedded photoanodes result in 6× enhancement. By varying nanoparticle concentration in the photoanodes, we observed ∼245× less Au-AgNSs are required relative to AuNPs to generate similar photocurrent enhancement for solar fuel conversion. Power-dependent measurements of Au-AgNSs and AuNPs showed a first order dependence to incident light intensity, relative to half-order dependence for TiO2 only photoanodes. This indicated that plasmonic nanostructures enhance charge carriers formed on the surface of the TiO2 which effectively participate in photochemical reactions. Our experiments and simulations suggest the enhanced near-field, far-field, and multipolar resonances of Au-AgNSs facilitating broadband absorption of solar radiation collectively gives rise to their superior performance in water splitting.

  13. Characteristics of silver nanoparticles in vehicles for biological applications.

    PubMed

    Kejlová, Kristina; Kašpárková, Věra; Krsek, Daniel; Jírová, Dagmar; Kolářová, Hana; Dvořáková, Markéta; Tománková, Kateřina; Mikulcová, Veronika

    2015-12-30

    Silver nanoparticles (AgNPs) have been used for decades as anti-bacterial agents in various industrial fields such as cosmetics, health industry, food storage, textile coatings and environmental applications, although their toxicity is not fully recognized yet. Antimicrobial and catalytic activity of AgNPs depends on their size as well as structure, shape, size distribution, and physico-chemical environment. The unique properties of AgNPs require novel or modified toxicological methods for evaluation of their toxic potential combined with robust analytical methods for characterization of nanoparticles applied in relevant vehicles, e.g., culture medium with/without serum and phosphate buffered saline. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Penetration of nanoparticles in flax (Linum usitatissimum L.) calli and regenerants.

    PubMed

    Kokina, Inese; Gerbreders, Vjačeslavs; Sledevskis, Eriks; Bulanovs, Andrejs

    2013-05-20

    We demonstrate a method for direct delivery of metal nanoparticles to flax calli and regenerant cells by vacuum deposition of metal nanolayers on powdered hormone followed by dispersal of the combined hormone-metal in medium. The penetration and location of the gold (AuNPs) and silver (AgNPs) nanoparticles in calli and in plant regenerants were confirmed by optical absorption spectroscopy and scanning electron microscopy. We detected a significant effect of the AuNPs and AgNPs on the regeneration type of flax calli. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. pH tunability and influence of alkali metal basicity on the plasmonic resonance of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Yadav, Vijay D.; Akhil Krishnan, R.; Borade, Lalit; Shirolikar, Seema; Jain, Ratnesh; Dandekar, Prajakta

    2017-07-01

    Localized surface plasmon resonance has been a unique and intriguing feature of silver nanoparticles (AgNPs) that has attracted immense attention. This has led to an array of applications for AgNPs in optics, sensors, plasmonic imaging etc. Although numerous applications have been reported consistently, the importance of buffer and reaction parameters during the synthesis of AgNPs, is still unclear. In the present study, we have demonstrated the influence of parameters like pH, temperature and buffer conditions (0.1 M citrate buffer) on the plasmonic resonance of AgNPs. We found that neutral and basic pH (from alkali metal) provide optimum interaction conditions for nucleation of plasmon resonant AgNPs. Interestingly, this was not observed in the non-alkali metal base (ammonia). Also, when the nanoparticles synthesized from alkali metal base were incorporated in different buffers, it was observed that the nanoparticles dissolved in the acidic buffer and had reduced plasmonic resonance intensity. This, however, was resolved in the basic buffer, increasing the plasmonic resonance intensity and confirming that nucleation of nanoparticles required basic conditions. The above inference has been supported by characterization of AgNPs using UV-Vis spectrophotometer, Fluorimetry analysis, Infrared spectrometer and TEM analysis. The study concluded that the plasmonic resonance of AgNPs occurs due to the interaction of alkali (Na) and transition metal (Ag) salt in basic/neutral conditions, at a specific temperature range, in presence of a capping agent (citric acid), providing a pH tune to the overall system.

  16. Biosynthesized silver and gold nanoparticles are potent antimycotics against opportunistic pathogenic yeasts and dermatophytes.

    PubMed

    Rónavári, Andrea; Igaz, Nóra; Gopisetty, Mohana Krishna; Szerencsés, Bettina; Kovács, Dávid; Papp, Csaba; Vágvölgyi, Csaba; Boros, Imre Miklós; Kónya, Zoltán; Kiricsi, Mónika; Pfeiffer, Ilona

    2018-01-01

    Epidemiologic observations indicate that the number of systemic fungal infections has increased significantly during the past decades, however in human mycosis, mainly cutaneous infections predominate, generating major public health concerns and providing much of the impetus for current attempts to develop novel and efficient agents against cutaneous mycosis causing species. Innovative, environmentally benign and economic nanotechnology-based approaches have recently emerged utilizing principally biological sources to produce nano-sized structures with unique antimicrobial properties. In line with this, our aim was to generate silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) by biological synthesis and to study the effect of the obtained nanoparticles on cutaneous mycosis causing fungi and on human keratinocytes. Cell-free extract of the red yeast Phaffia rhodozyma proved to be suitable for nanoparticle preparation and the generated AgNPs and AuNPs were characterized by transmission electron microscopy, dynamic light scattering and X-ray powder diffraction. Antifungal studies demonstrated that the biosynthesized silver particles were able to inhibit the growth of several opportunistic Candida or Cryptococcus species and were highly potent against filamentous Microsporum and Trichophyton dermatophytes. Among the tested species only Cryptococcus neoformans was susceptible to both AgNPs and AuNPs. Neither AgNPs nor AuNPs exerted toxicity on human keratinocytes. Our results emphasize the therapeutic potential of such biosynthesized nanoparticles, since their biocompatibility to skin cells and their outstanding antifungal performance can be exploited for topical treatment and prophylaxis of superficial cutaneous mycosis.

  17. Silver bioaccumulation dynamics in a freshwater invertebrate after aqueous and dietary exposures to nanosized and ionic Ag

    USGS Publications Warehouse

    le Croteau, Marie-Noe; Misra, Superb K.; Luoma, Samuel N.; Valsami-Jones, Eugenia

    2011-01-01

    We compared silver (Ag) bioavailability and toxicity to a freshwater gastropod after exposure to ionic silver (Ag+) and to Ag nanoparticles (Ag NPs) capped with citrate or with humic acid. Silver form, exposure route, and capping agent influence Ag bioaccumulation dynamics in Lymnaea stagnalis. Snails efficiently accumulated Ag from all forms after either aqueous or dietary exposure. For both exposure routes, uptake rates were faster for Ag+ than for Ag NPs. Snails efficiently assimilated Ag from Ag NPs mixed with diatoms (assimilation efficiency (AE) ranged from 49 to 58%) and from diatoms pre-exposed to Ag+ (AE of 73%). In the diet, Ag NPs damaged digestion. Snails ate less and inefficiently processed the ingested food, which adversely impacted their growth. Loss rates of Ag were faster after waterborne exposure to Ag NPs than after exposure to dissolved Ag+. Once Ag was taken up from diet, whether from Ag+ or Ag NPs, Ag was lost extremely slowly. Large Ag body concentrations are thus expected in L. stagnalis after dietborne exposures, especially to citrate-capped Ag NPs. Ingestion of Ag associated with particulate materials appears as the most important vector of uptake. Nanosilver exposure from food might trigger important environmental risks.

  18. Microbial Biosynthesis of Silver Nanoparticles in Different Culture Media.

    PubMed

    Luo, Ke; Jung, Samuel; Park, Kyu-Hwan; Kim, Young-Rok

    2018-01-31

    Microbial biosynthesis of metal nanoparticles has been extensively studied for the applications in biomedical sciences and engineering. However, the mechanism for their synthesis through microorganism is not completely understood. In this study, several culture media were investigated for their roles in the microbial biosynthesis of silver nanoparticles (AgNPs). The size and morphology of the synthesized AgNPs were analyzed by UV-vis spectroscopy, Fourier-transform-infrared (FT-IR), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The results demonstrated that nutrient broth (NB) and Mueller-Hinton broth (MHB) among tested media effectively reduced silver ions to form AgNPs with different particle size and shape. Although the involved microorganism enhanced the reduction of silver ions, the size and shape of the particles were shown to mainly depend on the culture media. Our findings suggest that the growth media of bacterial culture play an important role in the synthesis of metallic nanoparticles with regard to their size and shape. We believe our findings would provide useful information for further exploration of microbial biosynthesis of AgNPs and their biomedical applications.

  19. Using nuclear microscopy to characterize the interaction of textile-used silver nanoparticles with a biological wastewater treatment system

    NASA Astrophysics Data System (ADS)

    Bento, J. B.; Franca, R. D. G.; Pinheiro, T.; Alves, L. C.; Pinheiro, H. M.; Lourenço, N. D.

    2017-08-01

    The use of engineered nanoparticles in the textile industry has been rapidly increasing but their fate during biological wastewater treatment is largely unknown. The goal of the current study was to characterize the interaction of silver nanoparticles (AgNPs), used in the textile industry, with a biological wastewater treatment system based on aerobic granular sludge (AGS). The exposure tests were performed using a laboratory-scale sequencing batch reactor (SBR) system with AGS. The behavior and fate of textile AgNPs in the AGS system was studied with nuclear microscopy techniques. Elemental maps of AGS samples collected from the SBR showed that AgNPs typically clustered in agglomerates of small dimensions (<10 μm), which were preferentially associated with extracellular polymeric substances (EPS). This preliminary study highlights the potential application of nuclear microscopy for the characterization of the behavior and fate of AgNPs in AGS. The detailed compartmentalization of AgNPs in AGS components obtained with nuclear microscopy provides new and relevant information concerning AgNPs retention. This will be important in biotechnological terms to delineate strategies for AgNPs removal from textile wastewater.

  20. Microbial glycolipoprotein-capped silver nanoparticles as emerging antibacterial agents against cholera.

    PubMed

    Gahlawat, Geeta; Shikha, Sristy; Chaddha, Baldev Singh; Chaudhuri, Saumya Ray; Mayilraj, Shanmugam; Choudhury, Anirban Roy

    2016-02-01

    With the increased number of cholera outbreaks and emergence of multidrug resistance in Vibrio cholerae strains it has become necessary for the scientific community to devise and develop novel therapeutic approaches against cholera. Recent studies have indicated plausibility of therapeutic application of metal nano-materials. Among these, silver nanoparticles (AgNPs) have emerged as a potential antimicrobial agent to combat infectious diseases. At present nanoparticles are mostly produced using physical or chemical techniques which are toxic and hazardous. Thus exploitation of microbial systems could be a green eco-friendly approach for the synthesis of nanoparticles having similar or even better antimicrobial activity and biocompatibility. Hence, it would be worth to explore the possibility of utilization of microbial silver nanoparticles and their conjugates as potential novel therapeutic agent against infectious diseases like cholera. The present study attempted utilization of Ochrobactrum rhizosphaerae for the production of AgNPs and focused on investigating their role as antimicrobial agents against cholera. Later the exopolymer, purified from the culture supernatant, was used for the synthesis of spherical shaped AgNPs of around 10 nm size. Further the exopolymer was characterized as glycolipoprotein (GLP). Antibacterial activity of the novel GLP-AgNPs conjugate was evaluated by minimum inhibitory concentration, XTT reduction assay, scanning electron microscopy (SEM) and growth curve analysis. SEM studies revealed that AgNPs treatment resulted in intracellular contents leakage and cell lysis. The potential of microbially synthesized nanoparticles, as novel therapeutic agents, is still relatively less explored. In fact, the present study first time demonstrated that a glycolipoprotein secreted by the O. rhizosphaerae strain can be exploited for production of AgNPs which can further be employed to treat infectious diseases. Although this type of polymer has

  1. Biosynthesis of silver nanoparticles using bark extracts of Butea monosperma (Lam.) Taub. and study of their antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Das, Manoja; Smita, Soumya Shuvra

    2018-03-01

    Biosynthesis of silver nanoparticles was achieved using bark extract of Butea monosperma (Lam.) Taub., a native plant of Indian subcontinent and southeast Asia. The plant parts are familiar for ailment of different diseases. The bioactive compounds present in bark of the plant were extracted with Soxhlet extractor. Silver nitrate (AgNO3) was used as a raw material for preparation of silver nanoparticles (AgNPs). The ratio of bark extract and silver nitrate solution for synthesis of AgNPs was standardized as 3:5. The change in colour of the solution from pale yellow to deep brown can be correlated to reduction reaction catalyzed by plant bioactive compounds. The formation of AgNPs was confirmed by UV-Vis spectrophotometer. The surface plasmon resonance (SPR) maxima, λmax, were recorded at 452 nm. SPR indicates the nature and type of particles present in the solution. The suitable concentration of AgNO3 was found to be 10 mM to carry out reduction reaction with the bark extract. Alkaline environment (pH 9) suitably promotes the reaction. FTIR graph of synthesized AgNPs shows the shifting peak of 3265.0 wavelength/cm and 1635.40 wavelength/cm indicates that AgNPs were coated with plant biomolecules, which is attributed to the stabilization of AgNPs. XRD and SEM photograph of the AgNPs showed that they were spherical in shape and capped with bioactive compounds. Thus, the synthesized AgNPs are more stable, less toxic and homogenous in shape. The average diameter of the nanoparticles was 81 nm. The synthesized AgNPs had efficacy against a Gram-negative bacteria (Escherichia coli), a Gram-positive bacteria (Staphylococcus aureus), and a mold (Aspergillus niger). The maximum conversion was 66%. From the present investigation, it can be concluded that the bioactive compounds present in the bark of Butea have the capacity to reduce silver ion into silver nanoparticles in aqueous condition and the synthesized AgNPs are stabilized and loss toxic. Moreover, they also possess

  2. Modifying Thermal Switchability of Liquid Crystalline Nanoparticles by Alkyl Ligands Variation

    PubMed Central

    Żuk, Maciej; Tupikowska, Martyna

    2018-01-01

    By coating plasmonic nanoparticles (NPs) with thermally responsive liquid crystals (LCs) it is possible to prepare reversibly reconfigurable plasmonic nanomaterials with prospective applications in optoelectronic devices. However, simple and versatile methods to precisely tailor properties of liquid-crystalline nanoparticles (LC NPs) are still required. Here, we report a new method for tuning structural properties of assemblies of nanoparticles grafted with a mixture of promesogenic and alkyl thiols, by varying design of the latter. As a model system, we used Ag and Au nanoparticles that were coated with three-ring promesogenic molecules and dodecanethiol ligand. These LC NPs self-assemble into switchable lamellar (Ag NPs) or tetragonal (Au NPs) aggregates, as determined with small angle X-ray diffraction and transmission electron microscopy. Reconfigurable assemblies of Au NPs with different unit cell symmetry (orthorombic) are formed if hexadecanethiol and 1H,1H,2H,2H-perfluorodecanethiol were used in the place of dodecanethiol; in the case of Ag NPs the use of 11-hydroxyundecanethiol promotes formation of a lamellar structure as in the reference system, although with substantially broader range of thermal stability (140 vs. 90 °C). Our results underline the importance of alkyl ligand functionalities in determining structural properties of liquid-crystalline nanoparticles, and, more generally, broaden the scope of synthetic tools available for tailoring properties of reversibly reconfigurable plasmonic nanomaterials. PMID:29518916

  3. Bio-fabricated silver nanoparticles preferentially targets Gram positive depending on cell surface charge.

    PubMed

    Mandal, Debasis; Kumar Dash, Sandeep; Das, Balaram; Chattopadhyay, Sourav; Ghosh, Totan; Das, Debasis; Roy, Somenath

    2016-10-01

    Recently bio-inspired experimental processes for synthesis of nanoparticles are receiving significant attention in nanobiotechnology. Silver nanoparticles (Ag NPs) have been used very frequently in recent times to the wounds, burns and bacterial infections caused by drug-resistant microorganisms. Though, the antibacterial effects of Ag NPs on some multi drug-resistant bacteria specially against Gram positive bacteria has been established, but further investigation is needed to elicit its effectiveness against Gram negatives and to identify the probable mechanism of action. Thus, the present study was conducted to synthesize Ag NPs using Andrographis paniculata leaf extract and to investigate its antibacterial efficacy. After synthesis process the biosynthesized nanoparticles were purified and characterized with the help of various physical measurement techniques which raveled their purity, stability and small size range. The antimicrobial activity of Ag NPs was determined against both Gram-positive Enterococcus faecalis and Gram-negative Proteus vulgaris. Results showed comparatively higher antibacterial efficacy of Ag NPs against Gram positive Enterococcus faecalis strains. It was found that greater difference in zeta potential values between Gram positive bacteria and Ag NPs triggers better internalization of the particles. Thus the cell surface charge played vital role in cell killing which was confirmed by surface zeta potential study. Finally it may be concluded that green synthesized Ag NPs using Andrographis paniculata leaf extract can be very useful against both multi drug resistant Gram-positive and Gram-negative bacteria. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  4. Digestive cell lysosomes as main targets for Ag accumulation and toxicity in marine mussels, Mytilus galloprovincialis, exposed to maltose-stabilised Ag nanoparticles of different sizes.

    PubMed

    Jimeno-Romero, A; Bilbao, E; Izagirre, U; Cajaraville, M P; Marigómez, I; Soto, M

    2017-03-01

    Bioavailability and toxicity of maltose-stabilised AgNPs of different sizes (20, 40 and 100 nm) in mussels were compared with bulk and aqueous forms of the metal through a two-tier experimental approach. In the first tier, mussels were exposed for 3 d to a range of concentrations (0.75, 75, 750 μg Ag/l) in the form of Ag20-Mal, Ag40-Mal, Ag100-Mal, bulk Ag and aqueous Ag (as AgNO 3 ), as well as to the concentrations of maltose used in the formulation of NPs. Mortality, bioaccumulation, tissue and cell distribution and lysosomal responses were investigated. In the second tier, mussels were exposed for 21 d to Ag20-Mal, Ag100-Mal, bulk Ag and aqueous Ag at the lowest effective concentration selected after Tier 1 (0.75 μg Ag/l), biomarkers and toxicopathic effects were investigated. Aqueous Ag was lethal within 3 d at 75 μg Ag/l; Ag NPs or bulk Ag did not produce significant mortality at 750 μg Ag/l. Ag accumulation was limited and metallothionein gene transcription was not regulated although metal accumulation occurred in digestive, brown and stomach epithelial cells and in gut lumen after exposure to AgNPs and aqueous Ag starting at low concentrations after 1 d. Electrondense particles (<10 nm) in lysosomes and residual bodies after exposure to AgNPs contained Ag and S (X-ray). Intralysosomal metal accumulation and lysosomal membrane destabilisation were enhanced after exposure to all the forms of Ag and more marked after exposure to Ag20-Mal than to larger NPs. 21 d exposure to AgNPs provoked digestive cell loss and loss of digestive gland integrity, resulting in atrophy-necrosis in digestive alveoli and oedema/hyperplasia in gills (Ag NP), vacuolisation in digestive cells (aqueous Ag) and haemocyte infiltration of connective tissue (all treatments). Intralysosomal metal accumulation, lysosomal responses and toxicopathic effects are enhanced at decreasing sizes and appear to be caused by Ag +  ions released from NPs, although the metal was not

  5. Catechol-Functional Chitosan/Silver Nanoparticle Composite as a Highly Effective Antibacterial Agent with Species-Specific Mechanisms.

    PubMed

    Huang, Xiaofei; Bao, Xiaojiong; Liu, Yalan; Wang, Zhengke; Hu, Qiaoling

    2017-05-12

    In this study, silver nanoparticles (Ag NPs) coated with catechol-conjugated chitosan (CSS) were prepared using green methods. Interestingly, we uncovered that CSS-coated Ag NPs (CSS-Ag NPs) exhibited a higher toxicity against gram-negative Escherichia coli (E. coli) bacteria than against gram-positive Staphylococcus aureus (S. aureus) bacteria. The differences revealed that the CSS-Ag NPs killed gram bacteria with distinct, species-specific mechanisms. The aim of this study is to further investigate these underlying mechanisms through a series of analyses. The ultrastructure and morphology of the bacteria before and after treatment with CSS-Ag NPs were observed. The results demonstrated the CSS-Ag NPs killed gram-positive bacteria through a disorganization of the cell wall and leakage of cytoplasmic content. In contrast, the primary mechanism of action on gram-negative bacteria was a change in membrane permeability, induced by adsorption of CSS-Ag NPs. The species-specific mechanisms are caused by structural differences in the cell walls of gram bacteria. Gram-positive bacteria are protected from CSS-Ag NPs by a thicker cell wall, while gram-negatives are more easily killed due to an interaction between a special outer membrane and the nanoparticles. Our study offers an in-depth understanding of the antibacterial behaviors of CSS-Ag NPs and provides insights into ultimately optimizing the design of Ag NPs for treatment of bacterial infections.

  6. Multicolor Layer-by-Layer films using weak polyelectrolyte assisted synthesis of silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Rivero, Pedro Jose; Goicoechea, Javier; Urrutia, Aitor; Matias, Ignacio Raul; Arregui, Francisco Javier

    2013-10-01

    In the present study, we show that silver nanoparticles (AgNPs) with different shape, aggregation state and color (violet, green, orange) have been successfully incorporated into polyelectrolyte multilayer thin films using the layer-by-layer (LbL) assembly. In order to obtain colored thin films based on AgNPs is necessary to maintain the aggregation state of the nanoparticles, a non-trivial aspect in which this work is focused on. The use of Poly(acrylic acid, sodium salt) (PAA) as a protective agent of the AgNPs is the key element to preserve the aggregation state and makes possible the presence of similar aggregates (shape and size) within the LbLcolored films. This approach based on electrostatic interactions of the polymeric chains and the immobilization of AgNPs with different shape and size into the thin films opens up a new interesting perspective to fabricate multicolornanocomposites based on AgNPs.

  7. Synthesis, characterization and optical properties of gelatin doped with silver nanoparticles.

    PubMed

    Mahmoud, K H; Abbo, M

    2013-12-01

    In this study, silver nanoparticles were synthesized by chemical reduction of silver salt (AgNO3) solution. Formation of nanoparticles was confirmed by UV-visible spectrometry. The surface plasmon resonance peak is located at 430 nm. Doping of silver nanoparticles (Ag NPs) with gelatin biopolymer was studied. The silver content in the polymer matrix was in the range of 0.4-1 wt%. The formation of nanoparticles disappeared for silver content higher than 1 wt%. The morphology and interaction of gelatin doped with Ag NPs was examined by transmission electron microscopy and FTIR spectroscopy. The content of Ag NPs has a pronounced effect on optical and structural properties of gelatin. Optical parameters such as refractive index, complex dielectric constant were calculated. The dispersion of the refractive index was discussed in terms of the single--oscillator Wemple-DiDomenico model. Color properties of the prepared samples were discussed in the framework of CIE L(*)u(*)v(*) color space. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Synthesis, characterization and optical properties of gelatin doped with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Mahmoud, K. H.; Abbo, M.

    2013-12-01

    In this study, silver nanoparticles were synthesized by chemical reduction of silver salt (AgNO3) solution. Formation of nanoparticles was confirmed by UV-visible spectrometry. The surface plasmon resonance peak is located at 430 nm. Doping of silver nanoparticles (Ag NPs) with gelatin biopolymer was studied. The silver content in the polymer matrix was in the range of 0.4-1 wt%. The formation of nanoparticles disappeared for silver content higher than 1 wt%. The morphology and interaction of gelatin doped with Ag NPs was examined by transmission electron microscopy and FTIR spectroscopy. The content of Ag NPs has a pronounced effect on optical and structural properties of gelatin. Optical parameters such as refractive index, complex dielectric constant were calculated. The dispersion of the refractive index was discussed in terms of the single - oscillator Wemple-DiDomenico model. Color properties of the prepared samples were discussed in the framework of CIE L*u*v* color space.

  9. Enhancing UV-emissions through optical and electronic dual-function tuning of Ag nanoparticles hybridized with n-ZnO nanorods/p-GaN heterojunction light-emitting diodes.

    PubMed

    Yao, Yung-Chi; Yang, Zu-Po; Hwang, Jung-Min; Chuang, Yi-Lun; Lin, Chia-Ching; Haung, Jing-Yu; Chou, Chun-Yang; Sheu, Jinn-Kong; Tsai, Meng-Tsan; Lee, Ya-Ju

    2016-02-28

    ZnO nanorods (NRs) and Ag nanoparticles (NPs) are known to enhance the luminescence of light-emitting diodes (LEDs) through the high directionality of waveguide mode transmission and efficient energy transfer of localized surface plasmon (LSP) resonances, respectively. In this work, we have demonstrated Ag NP-incorporated n-ZnO NRs/p-GaN heterojunctions by facilely hydrothermally growing ZnO NRs on Ag NP-covered GaN, in which the Ag NPs were introduced and randomly distributed on the p-GaN surface to excite the LSP resonances. Compared with the reference LED, the light-output power of the near-band-edge (NBE) emission (ZnO, λ = 380 nm) of our hybridized structure is increased almost 1.5-2 times and can be further modified in a controlled manner by varying the surface morphology of the surrounding medium of the Ag NPs. The improved light-output power is mainly attributed to the LSP resonance between the NBE emission of ZnO NRs and LSPs in Ag NPs. We also observed different behaviors in the electroluminescence (EL) spectra as the injection current increases for the treatment and reference LEDs. This observation might be attributed to the modification of the energy band diagram for introducing Ag NPs at the interface between n-ZnO NRs and p-GaN. Our results pave the way for developing advanced nanostructured LED devices with high luminescence efficiency in the UV emission regime.

  10. Controlling silver nanoparticle exposure in algal toxicity testing – A matter of timing

    PubMed Central

    Baun, Anders

    2015-01-01

    The aquatic ecotoxicity testing of nanoparticles is complicated by unstable exposure conditions resulting from various transformation processes of nanoparticles in aqueous suspensions. In this study, we investigated the influence of exposure timing on the algal test response to silver nanoparticles (AgNPs), by reducing the incubation time and by aging the AgNPs in algal medium prior to testing. The freshwater green algae Pseudokirchneriella subcapitata were exposed to AgNO3, NM-300 K (a representative AgNP) and citrate stabilized AgNPs from two different manufacturers (AgNP1 and AgNP2) in a standard algal growth inhibition test (ISO 8692:2004) for 48 h and a short-term (2 h) 14C-assimilation test. For AgNO3, similar responses were obtained in the two tests, whereas freshly prepared suspensions of citrate stabilized AgNPs were less toxic in the 2-h tests compared to the 48-h tests. The 2-h test was found applicable for dissolved silver, but yielded non-monotonous concentration–response relationships and poor reproducibility for freshly prepared AgNP suspensions. However, when aging AgNPs in algal medium 24 h prior to testing, clear concentration–response patterns emerged and reproducibility increased. Prolonged aging to 48 h increased toxicity in the 2-h tests whereas aging beyond 48 h reduced toxicity. Our results demonstrate that the outcome of algal toxicity testing of AgNPs is highly influenced not only by the test duration, but also by the time passed from the moment AgNPs are added to the test medium. This time-dependency should be considered when nanomaterial dispersion protocols for ecotoxicity testing are developed. PMID:24842597

  11. Enhanced antimicrobial activities of silver-nanoparticle-decorated reduced graphene nanocomposites against oral pathogens.

    PubMed

    Peng, Jian-Min; Lin, Jia-Cheng; Chen, Zhuo-Yu; Wei, Meng-Chao; Fu, Yuan-Xiang; Lu, Shu-Shen; Yu, Dong-Sheng; Zhao, Wei

    2017-02-01

    As a means of capitalizing on the synergistic properties between reduced graphene nanosheets (R-GNs) and silver nanoparticles (AgNPs), an efficient and convenient chemical reduction method was used to prepare silver-nanoparticle-decorated reduced graphene nanocomposites (R-GNs/Ag). The products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, which confirmed the loading of well-dispersed silver nanoparticles on reduced graphene sheets. Their antimicrobial activities against oral pathogens such as Candida albicans, Lactobacillus acidophilus, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were investigated by MIC determination, the counting of colony-forming units (CFU), agar diffusion tests, and growth curve observation. Compared with pure R-GNs and AgNPs, R-GNs/Ag composites exhibited enhanced antimicrobial properties owing to highly dispersed AgNPs on R-GNs. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Biosynthesis of gold and silver chloride nanoparticles mediated by Crataegus pinnatifida fruit extract: in vitro study of anti-inflammatory activities.

    PubMed

    Kang, Jong Pyo; Kim, Yeon Ju; Singh, Priyanka; Huo, Yue; Soshnikova, Veronika; Markus, Josua; Ahn, Sungeun; Chokkalingam, Mohan; Lee, Hyun A; Yang, Deok Chun

    2017-09-18

    This research article investigates the one-pot synthesis of gold and silver chloride nanoparticles functionalized by fruit extract of Crataegus pinnatifida as reducing and stabilizing agents and their possible roles as novel anti-inflammatory agents. Hawthorn (C. pinnatifida) fruits are increasingly popular as raw materials for functional foods and anti-inflammatory potential agents because of abundant flavonoids. The reduction of auric chloride and silver nitrate by the aqueous fruit extract led to the formation of gold and silver chloride nanoparticles. The nanoparticles were further characterized by field emission transmission electron microscopy indicated that CP-AuNps and CP-AgClNps were hexagonal and cubic shape, respectively. According to X-ray diffraction results, the average crystallite sizes of CP-AuNps and CP-AgClNps were 14.20 nm and 24.80 nm. The biosynthesized CP-AgClNps served as efficient antimicrobial agents against Escherichia coli and Staphylococcus aureus. Furthermore, CP-AuNps and CP-AgClNps enhanced the DPPH radical scavenging activity of the fruit extract. Lastly, MTT assay of nanoparticles demonstrated low toxicity in murine macrophage (RAW264.7). Biosynthesized nanoparticles also reduced the production of the inflammatory cytokines including nitric oxide and prostaglandin E2 in lipopolysaccharide-induced RAW264.7 cells. Altogether, these findings suggest that CP-AuNps and CP-AgClNps can be used as novel drug carriers or biosensors with intrinsic anti-inflammatory activity.

  13. Three Phoma spp. synthesised novel silver nanoparticles that possess excellent antimicrobial efficacy.

    PubMed

    Rai, Mahendra; Ingle, Avinash P; Gade, Aniket K; Duarte, Marta Cristina Teixeira; Duran, Nelson

    2015-10-01

    The authors report extracellular mycosynthesis of silver nanoparticles (AgNPs) by Phoma capsulatum, Phoma putaminum and Phoma citri. The AgNPs thus synthesised were characterised by UV-visible spectrophotometer, Fourier transform infrared spectroscopy, Nanosight LM20 and transmission electron microscopy, which confirmed the synthesis of mostly spherical and polydisperse nanoparticles capped with proteins. The size of AgNPs was found in the range of 10-80 , 5-80 and 5-90 nm with an average size of 31.85, 25.43 and 23.29 nm by P. capsulatum, P. putaminum and P. citri, respectively. Further, potential antimicrobial activity was reported against Aspergillus niger, Candida albicans, Salmonella choleraesuis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. The lowest minimal inhibitory concentration (MIC) (0.85 µg/ml) was reported for AgNPs synthesised from P. citri against S. choleraesuis. However, AgNPs synthesised from P. capsulatum showed the highest MIC (10.62 µg/ml) against S. choleraesuis, P. aeruginosa and E. coli (clinical isolate). The same MIC values (10.62 µg/ml) were also reported against P. aeruginosa and both clinical and standard isolates of E. coli for AgNPs synthesised from P. citri. It was also observed that all the silver nanoparticles showed remarkable antifungal and antibacterial activity against these tested pathogens as compared with the commercially available antifungal and antibacterial agents.

  14. Green synthesis of high conductivity silver nanoparticle-reduced graphene oxide composite films

    NASA Astrophysics Data System (ADS)

    Dinh, D. A.; Hui, K. S.; Hui, K. N.; Cho, Y. R.; Zhou, Wei; Hong, Xiaoting; Chun, Ho-Hwan

    2014-04-01

    A green facile chemical approach to control the dimensions of Ag nanoparticles-graphene oxide (AgNPs/GO) composites was performed by the in situ ultrasonication of a mixture of AgNO3 and graphene oxide solutions with the assistance of vitamin C acting as an environmentally friendly reducing agent at room temperature. With decreasing ultrasonication time, the size of the Ag nanoparticles decreased and became uniformly distributed over the surface of the GO nanosheets. The as-prepared AgNPs/rGO composite films were then formed using a spin coating method and reduced at 500 °C under N2/H2 gas flow for 1 h. Four-point probe measurements showed that the sheet resistance of the AgNPs/rGO films decreased with decreasing AgNPs size. The lowest sheet resistance of 270 Ω/sq was obtained in the film corresponding to 1 min of ultrasonication, which showed a 40 times lower resistivity than the rGO film (10.93 kΩ/sq). The formation mechanisms of the as-prepared AgNPs/rGO films are proposed. This study provides a guide to controlling the dimensions of AgNPs/rGO films, which might hold promise as advanced materials for a range of analytical applications, such as catalysis, sensors and microchips.

  15. Silver nanoparticles induced heat shock protein 70, oxidative stress and apoptosis in Drosophila melanogaster.

    PubMed

    Ahamed, Maqusood; Posgai, Ryan; Gorey, Timothy J; Nielsen, Mark; Hussain, Saber M; Rowe, John J

    2010-02-01

    Due to the intensive commercial application of silver nanoparticles (Ag NPs), risk assessment of this nanoparticle is of great importance. Our previous in vitro study demonstrated that Ag NPs caused DNA damage and apoptosis in mouse embryonic stem cells and fibroblasts. However, toxicity of Ag NPs in vivo is largely lacking. This study was undertaken to examine the toxic effects of well-characterized polysaccharide coated 10 nm Ag NPs on heat shock stress, oxidative stress, DNA damage and apoptosis in Drosophila melanogaster. Third instar larvae of D. melanogaster were fed a diet of standard cornmeal media mixed with Ag NPs at the concentrations of 50 and 100 microg/ml for 24 and 48 h. Ag NPs up-regulated the expression of heat shock protein 70 and induced oxidative stress in D. melanogaster. Malondialdehyde level, an end product of lipid peroxidation was significantly higher while antioxidant glutathione content was significantly lower in Ag NPs exposed organisms. Activities of antioxidant enzyme superoxide dismutase and catalase were also significantly higher in the organisms exposed to Ag NPs. Furthermore, Ag NPs up-regulated the cell cycle checkpoint p53 and cell signaling protein p38 that are involved in the DNA damage repair pathway. Moreover, activities of caspase-3 and caspase-9, markers of apoptosis were significantly higher in Ag NPs exposed organisms. The results indicate that Ag NPs in D. melanogaster induce heat shock stress, oxidative stress, DNA damage and apoptosis. This study suggests that the organism is stressed and thus warrants more careful assessment of Ag NPs using in vivo models to determine if chronic exposure presents developmental and reproductive toxicity. Copyright 2009 Elsevier Inc. All rights reserved.

  16. A novel multifunctional electrochemical platform for simultaneous detection, elimination, and inactivation of pathogenic bacteria based on the Vancomycin-functionalised AgNPs/3D-ZnO nanorod arrays.

    PubMed

    Yang, Zhiqing; Wang, Yi; Zhang, Dun

    2017-12-15

    A novel fast, sensitive, and specific multifunctional electrochemical platform has been proposed for simultaneous detection, elimination, and inactivation of pathogenic bacteria for the first time. The platform is constituted with three-dimensional ZnO nanorod arrays (3D-ZnO) decorated with sliver nanoparticles (AgNPs) and functionalized with vancomycin (Van). Based on the specific recognition of Van for Gram-positive bacteria, the fabricated electrochemical platform has presented high detection sensitivity to Staphylococcus aureus with a low detection limit of 330cfu/mL and adaptable bacterial-elimination efficiency (50%) at low concentrations (1000-2000cfu/mL). Moreover, the platform has shown high antibacterial activity (99.99%) arising from the synergistic germicidal effect of the composited antibacterial AgNPs and Van units. The current work could provide new strategies to construct advanced platforms for simultaneous detection, elimination, and inactivation of various pathogenic bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Sunlight mediated synthesis of silver nanoparticles using redox phytoprotein and their application in catalysis and colorimetric mercury sensing.

    PubMed

    Ahmed, Khan Behlol Ayaz; Senthilnathan, Rajendran; Megarajan, Sengan; Anbazhagan, Veerappan

    2015-10-01

    Owing to the benign nature, plant extracts mediated green synthesis of metal nanoparticles (NPs) is rapidly expanding. In this study, we demonstrated the successful green synthesis of silver nanoparticles (AgNPs) by utilizing natural sunlight and redox protein complex composed of ferredoxin-NADP(+) reductase (FNR) and ferredoxin (FD). The capping and stabilization of the AgNPs by the redox protein was confirmed by Fourier transform infrared spectroscopy. Light and redox protein is the prerequisite factor for the formation of AgNPs. The obtained result shows that the photo generated free radicals by the redox protein is responsible for the reduction of Ag(+) to Ag(0). Transmission electron microscopy revealed the formation of spherical AgNPs with size ranging from 10 to 15 nm. As-prepared AgNPs exhibit excellent catalytic activity toward the degradation of hazardous organic dyes, such as methylene blue, methyl orange and methyl red. These bio-inspired AgNPs is highly sensitive and selective in sensing hazardous mercury ions in the water at micromolar concentration. In addition, FNR/FD extract stabilized AgNPs showed good antimicrobial activity against gram positive and gram negative bacteria. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Optical properties of functional composite silver nanoparticles and their potential use in reproductive medicine

    NASA Astrophysics Data System (ADS)

    Syrvatka, Vasyl J.; Slyvchuk, Yurij I.; Rozgoni, Ivan I.; Gevkan, Ivan I.; Bilyy, Oleksandr I.

    2013-06-01

    Silver nanoparticles are promising product of nanotechnology with attractive physicochemical and biological properties. The main aim of the study was to investigate optical properties of functional silver nanoparticles with different composite agents: polyvinylpyrrolidone, bovine serum albumin, hyaluronan and to explore their potential using in reproductive medicine. The date obtained in the study showed that surface modification of nanoparticles leads to change of their optical, physicochemical and biological properties. The optical properties of silver nanoparticles display, that AgNPs with PVP and BSA is most stable in PBS than AgNPs with HA. However the absorption curves after 120 hours of storage show, that AgNPs-HA were the most stable in ethanol. Results show, that silver nanoparticles did not effect on sperm viability and motility, but cause a changes of some biochemical parameters of conditioned medium, particular increase the concentration of triglycerides, activity of alkaline phosphatase, lactate dehydrogenase and decrease the activity of aspartate aminotransferase and alanine aminotransferase after 3 h of in vitro cultivation at 37°C. According to our latest data AgNPs with HA have a less toxic effect on biological processes in rabbits sperm compared with AgNPs with PVP and BSA. Nevertheless all functional composites of silver nanoparticles at the concentration of 0.1 μg/mL have no toxic effect on spermatozoa and can be successfully applied in reproductive medicine at low concentrations as signal enhancers, optical sensors, and biomarkers.

  19. Effect of different densities of silver nanoparticles on neuronal growth

    NASA Astrophysics Data System (ADS)

    Nissan, Ifat; Schori, Hadas; Lipovsky, Anat; Alon, Noa; Gedanken, Aharon; Shefi, Orit

    2016-08-01

    Nerve regeneration has become a subject of great interest, and much effort is devoted to the design and manufacturing of effective biomaterials. In this paper, we report the capability of surfaces coated with silver nanoparticles (AgNPs) to serve as platforms for nerve regeneration. We fabricated substrates coated with silver nanoparticles at different densities using sonochemistry, and grew neuroblastoma cells on the AgNPs. The effect of the different densities on the development of the neurites during the initiation and elongation growth phases was studied. We found that the AgNPs function as favorable anchoring sites for the neuroblastoma cells, significantly enhancing neurite outgrowth. One of the main goals of this study is to test whether the enhanced growth of the neurites is due to the mere presence of AgNPs or whether their topography also plays a vital role. We found that this phenomenon was repeated for all the tested densities, with a maximal effect for the substrates that are coated with 45 NPs/μm2. We also studied the amount of reactive oxygen spices (ROS) in the presence of AgNPs as indicator of cell activation. Our results, combined with the well-known antibacterial effects of AgNPs, suggest that substrates coated with AgNP are attractive nanomaterials—with dual activity—for neuronal repair studies and therapeutics.

  20. Integrative assessment of the effects produced by Ag nanoparticles at different levels of biological complexity in Eisenia fetida maintained in two standard soils (OECD and LUFA 2.3).

    PubMed

    Garcia-Velasco, N; Peña-Cearra, A; Bilbao, E; Zaldibar, B; Soto, M

    2017-08-01

    There is a potential risk to increase the release of silver nanoparticles (Ag NPs) into the environment: For instance. in soils receiving sludge models estimate 0.007 mg Ag NPs kg -1 that will annually increase due to sludge or sludge incineration residues land-disposal. Thus, the concern about the hazards of nanosilver to soils and soil invertebrates is growing. Studies performed up to now have been focused in traditional endpoints, used limit range concentrations and employed different soil types that differ in physico-chemical characteristics. Presently, effects of Ag NPs have been measured at different levels of biological complexity in Eisenia fetida, exposed for 3 and 14 d to high but sublethal (50 mg Ag NPs kg -1 ) and close to modeled environmental concentrations (0.05 mg Ag NPs kg -1 ). Since characteristics of the exposure matrix may limit the response of the organisms to these concentrations, experiments were carried out in OECD and LUFA soils, the most used standard soils. High concentrations of Ag NPs increased catalase activity and DNA damage in OECD soils after 14 d while in LUFA 2.3 soils produced earlier effects (weight loss, decrease in cell viability and increase in catalase activity at day 3). At day 14, LUFA 2.3 (low clay and organic matter-OM-) could have provoked starvation of earthworms, masking Ag NPs toxicity. The concentration close to modeled environmental concentrations produced effects uniquely in LUFA 2.3 soil. Accurate physico-chemical characteristics of the standard soils are crucial to assess the toxicity exerted by Ag NPs in E. fetida since low clay and OM contents can be considered toxicity enhancers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Ameliorative role of nano-ceria against amine coated Ag-NP induced toxicity in Labeo rohita

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Saleem; Qureshi, Naureen Aziz; Jabeen, Farhat

    2018-03-01

    Silver nanoparticles (Ag-NPs) and its byproducts can spread pollution in aquatic habitat. Liver and gills are key target for toxicity. Oxidative stress, tissue alterations, and hemotoxicity are assumed to be associated with Ag-NPs in target animals. Cerium oxide nanoparticles (nano-ceria) show antioxidant potential in scavenging the free radicals generated in Ag-NP-induced oxidative stress. We determined ameliorated role of nano-ceria against Ag-NP-induced toxicity in fresh water Labeo rohita (L. rohita). Four groups were used in study including control, nano-ceria, Ag-NPs, and Ag-NPs + nano-ceria. Ag-NPs (30 mg l-1) and nano-ceria (50 µg kg-1) were given through water and prepared feed, respectively. The samples were taken after 28 days. Results demonstrated that pre-treatment of nano-ceria recovered L. rohita from Ag-NP-induced toxicity and oxidative stress. Nano-ceria pre-treatment actively mimics the activity of GST, GSH, CAT, and SOD. Furthermore, Ag-NPs' treatment caused severe inflammation and necrosis in hepatic parenchyma which leaded to congestion of blood in hepatic tissues. Accumulation of a yellow pigment in hepatic tissue was also seen due to necrosis of affected cells. In nano-ceria pre-treatment, there was no congestion in hepatic tissue. Vacuolization of cells and necrosis in some area was recorded in nano-ceria pre-treated group, but the gill and hepatic tissue showed improvement against Ag-NP-induced damage. Nano-ceria pre-treatment also improved hematological parameters in Ag-NP-treated fish. This study concluded that Ag-NP-induced toxicity in treated fish and pre-treatment of nano-ceria show ameliorative role.

  2. Silver deposited carboxymethyl chitosan-grafted magnetic nanoparticles as dual action deliverable antimicrobial materials.

    PubMed

    Vo, Duc-Thang; Sabrina, Sabrina; Lee, Cheng-Kang

    2017-04-01

    Carboxymethyl chitosan (CMCS) was known to have a much better antimicrobial activity than chitosan due to the increased cationic -NH 3 + groups resulted from the intra- and intermolecular interactions between the carboxyl and amino groups. CMCS was grafted onto the surface of silica coated magnetic nanoparticles (MNPs) to obtain magnetically retrievable and deliverable antimicrobial nanoparticles (MNPs@CMCS). The presence of carboxylate groups in CMCS not only enhanced antimicrobial activity but also enabled Ag ions chelating ability to induce the in situ formation of Ag nanoparticles (AgNPs). The deposition of AgNPs on the surface of MNPs@CMCS could significantly increase its antimicrobial activity against planktonic cells due to the dual action of CMCS and AgNPs. Due to its high magnetism, the as-prepared MNPs@CMCS-Ag could be efficiently delivered into an existing biofilm under the guidance of an applied magnetic field. Without direct contact, the Ag ions and/or radical oxygen species (ROS) released from the deposited Ag nanoparticles could effectively kill the bacteria embedded in the extracellular polymeric substances (EPS) matrix of biofilm. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Investigation on the morphological and optical evolution of bimetallic Pd-Ag nanoparticles on sapphire (0001) by the systematic control of composition, annealing temperature and time.

    PubMed

    Pandey, Puran; Kunwar, Sundar; Sui, Mao; Bastola, Sushil; Lee, Jihoon

    2017-01-01

    Multi-metallic alloy nanoparticles (NPs) can offer additional opportunities for modifying the electronic, optical and catalytic properties by the control of composition, configuration and size of individual nanostructures that are consisted of more than single element. In this paper, the fabrication of bimetallic Pd-Ag NPs is systematically demonstrated via the solid state dewetting of bilayer thin films on c-plane sapphire by governing the temperature, time as well as composition. The composition of Pd-Ag bilayer remarkably affects the morphology of alloy nanostructures, in which the higher Ag composition, i.e. Pd0.25Ag0.75, leads to the enhanced dewetting of bilayers whereas the higher Pd composition (Pd0.75Ag0.25) hinders the dewetting. Depending on the annealing temperature, Pd-Ag alloy nanostructures evolve with a series of configurations, i.e. nucleation of voids, porous network, elongated nanoclusters and round alloy NPs. In addition, with the annealing time set, the gradual configuration transformation from the elongated to round alloy NPs as well as size reduction is demonstrated due to the enhanced diffusion and sublimation of Ag atoms. The evolution of various morphology of Pd-Ag nanostructures is described based on the surface diffusion and inter-diffusion of Pd and Ag adatoms along with the Ag sublimation, Rayleigh instability and energy minimization mechanism. The reflectance spectra of bimetallic Pd-Ag nanostructures exhibit various quadrupolar and dipolar resonance peaks, peak shifts and absorption dips owing to the surface plasmon resonance of nanostructures depending on the surface morphology. The intensity of reflectance spectra is gradually decreased along with the surface coverage and NP size evolution. The absorption dips are red-shifted towards the longer wavelength for the larger alloy NPs and vice-versa.

  4. Investigation on the morphological and optical evolution of bimetallic Pd-Ag nanoparticles on sapphire (0001) by the systematic control of composition, annealing temperature and time

    PubMed Central

    Pandey, Puran; Kunwar, Sundar; Sui, Mao; Bastola, Sushil

    2017-01-01

    Multi-metallic alloy nanoparticles (NPs) can offer additional opportunities for modifying the electronic, optical and catalytic properties by the control of composition, configuration and size of individual nanostructures that are consisted of more than single element. In this paper, the fabrication of bimetallic Pd-Ag NPs is systematically demonstrated via the solid state dewetting of bilayer thin films on c-plane sapphire by governing the temperature, time as well as composition. The composition of Pd-Ag bilayer remarkably affects the morphology of alloy nanostructures, in which the higher Ag composition, i.e. Pd0.25Ag0.75, leads to the enhanced dewetting of bilayers whereas the higher Pd composition (Pd0.75Ag0.25) hinders the dewetting. Depending on the annealing temperature, Pd-Ag alloy nanostructures evolve with a series of configurations, i.e. nucleation of voids, porous network, elongated nanoclusters and round alloy NPs. In addition, with the annealing time set, the gradual configuration transformation from the elongated to round alloy NPs as well as size reduction is demonstrated due to the enhanced diffusion and sublimation of Ag atoms. The evolution of various morphology of Pd-Ag nanostructures is described based on the surface diffusion and inter-diffusion of Pd and Ag adatoms along with the Ag sublimation, Rayleigh instability and energy minimization mechanism. The reflectance spectra of bimetallic Pd-Ag nanostructures exhibit various quadrupolar and dipolar resonance peaks, peak shifts and absorption dips owing to the surface plasmon resonance of nanostructures depending on the surface morphology. The intensity of reflectance spectra is gradually decreased along with the surface coverage and NP size evolution. The absorption dips are red-shifted towards the longer wavelength for the larger alloy NPs and vice-versa. PMID:29253017

  5. Fabrication of silver nanoparticle sponge leather with durable antibacterial property.

    PubMed

    Liu, Gongyan; Haiqi, Gao; Li, Kaijun; Xiang, Jun; Lan, Tianxiang; Zhang, Zongcai

    2018-03-15

    Leather product with durable antibacterial property is of great interest both from industry and consumer's point of view. To fabricate such functional leather, gallic acid modified silver nanoparticles (GA@AgNPs) were first in situ synthesized with a core-shell structure and an average size of 15.3nm. Due to its hydrophilic gallic acid surface, the GA@AgNPs possessed excellent stability and dispersibility in wide pH range from 3 to 12 and also showed effective antibacterial activity with a minimum inhibitory concentration (MIC) of around 10μgmL -1 . Then, such GA@AgNPs were used as retanning agent to be successfully filled into leather matrix during the leather manufacturing process. Moreover, taking the advantage of its high surface density of carboxyl groups, these GA@AgNPs could be further chemically cross-linked onto collagen fibers by chrome tanning agent. After retanning, the resultant leather was given a "AgNPs sponge" feature with high payload of silver nanoparticles against laundry, exhibiting high and durable antibacterial activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate

    PubMed Central

    2011-01-01

    Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP). The AgNPs remained stable throughout the duration of the 28-day oral toxicity study in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of AgNPs. Besides the intestinal system, the largest silver concentrations were detected in the liver and kidneys. Silver was also found in the lungs and brain. Autometallographic (AMG) staining revealed a similar cellular localization of silver in ileum, liver, and kidney tissue in rats exposed to AgNPs or AgAc. Using transmission electron microscopy (TEM), nanosized granules were detected in the ileum of animals exposed to AgNPs or AgAc and were mainly located in the basal lamina of the ileal epithelium and in lysosomes of macrophages within the lamina propria. Using energy dispersive x-ray spectroscopy it was shown that the granules in lysosomes consisted of silver, selenium, and sulfur for both AgNP and AgAc exposed rats. The diameter of the deposited granules was in the same size range as that of the administered AgNPs. No silver granules were detected by TEM in the liver. Conclusions The results of the present study demonstrate that the organ distribution of silver was similar when AgNPs or AgAc were administered orally to rats. The presence of silver granules containing

  7. Cube-like Fe3O4@SiO2@Au@Ag magnetic nanoparticles: a highly efficient SERS substrate for pesticide detection

    NASA Astrophysics Data System (ADS)

    Sun, Mei; Zhao, Aiwu; Wang, Dapeng; Wang, Jin; Chen, Ping; Sun, Henghui

    2018-04-01

    As a novel surface-enhanced Raman spectroscopic (SERS) nanocomposite, cube-like Fe3O4@SiO2@Au@Ag magnetic nanoparticles (NPs) were synthesized for the first time. Cube-like α-Fe2O3 NPs with uniform size were achieved by optimizing reaction temperature and time. Firstly, the cube-like Fe3O4@SiO2 with good dispersity was achieved by calcining α-Fe2O3@SiO2 NPs in hydrogen atmosphere at 360 °C for 2.5 h, followed by self-assembling a PEI shell via sonication. Furthermore, the Au@Ag particles were densely assembled on the Fe3O4@SiO2 NPs to form the Fe3O4@SiO2@Au@Ag composite structure via strong Ag-N interaction. The obtained nanocomposites exhibited an excellent SERS behavior, reflected by the low detection of limit (p-ATP) at the 5 × 10-14 M level. Moreover, these nanocubes were used for the detection of thiram, and the detection limit can reach 5 × 10-11 M. Meanwhile, the U.S. Environmental Protection Agency specifies that the residue in fruit must be lower than 7 ppm. Hence, the resulting substrate with high SERS activity has great practical potential applications in the rapid detection of chemical, biological, and environment pollutants with a simple portable Raman instrument at trace level.

  8. Characterization, antioxidant and cytotoxicity evaluation of green synthesized silver nanoparticles using Cleistanthus collinus extract as surface modifier

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kanipandian, Nagarajan; Kannan, Soundarapandian; Ramesh, Ramar

    Graphical abstract: The figure is the TEM image of green synthesized silver nanoparticles from Cleistanthus collinus. In this investigation we have used the poisonous plant as a reducing and capping agent. This is a first time data to synthesis the metal nanoparticles using poisonous plant. - Highlights: • A hitherto unreported venomous plant mediated AgNPs synthesis. • The particle size is observed in the range of 20–40 nm. • Surface morphology of the well-dispersed silver nanoparticles is studied using SEM and TEM. • Crystalline nature of AgNPs is confirmed by X-ray diffraction analysis. • Antioxidant activities of green synthesized AgNPsmore » are tested in vitro. - Abstract: We report, here a simple green method for the preparation of silver nanoparticles (AgNPs) using the plant extract of Cleistanthus collinus as potential phyto reducer. The synthesized AgNPs were characterized by UV–vis spectra, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The obtained results confirmed that the AgNPs were crystalline in nature and the morphological studies reveal the spherical shape of AgNPs with size ranging from 20 to 40 nm. The in vitro antioxidant activity of AgNPs showed a significant effect on scavenging of free radicals. The cytotoxicity study exhibited a dose-dependent effect against human lung cancer cells (A549) and normal cells (HBL-100), the inhibitory concentration (IC{sub 50}) were found to be 30 μg/mL and 60 μg/mL respectively. The in vivo histopathology of mouse organs proved that AgNPs does not possess toxic effect and can be extensively applied in biomedical sciences.« less

  9. Trojan-horse mechanism in the cellular uptake of silver nanoparticles verified by direct intra- and extracellular silver speciation analysis.

    PubMed

    Hsiao, I-Lun; Hsieh, Yi-Kong; Wang, Chu-Fang; Chen, I-Chieh; Huang, Yuh-Jeen

    2015-03-17

    The so-called "Trojan-horse" mechanism, in which nanoparticles are internalized within cells and then release high levels of toxic ions, has been proposed as a behavior in the cellular uptake of Ag nanoparticles (AgNPs). While several reports claim to have proved this mechanism by measuring AgNPs and Ag ions (I) in cells, it cannot be fully proven without examining those two components in both intra- and extracellular media. In our study, we found that even though cells take up AgNPs similarly to (microglia (BV-2)) or more rapidly than (astrocyte (ALT)) Ag (I), the ratio of AgNPs to total Ag (AgNPs+Ag (I)) in both cells was lower than that in outside media. It could be explained that H2O2, a major intracellular reactive oxygen species (ROS), reacts with AgNPs to form more Ag (I). Moreover, the major speciation of Ag (I) in cells was Ag(cysteine) and Ag(cysteine)2, indicating the possible binding of monomer cysteine or vital thiol proteins/peptides to Ag ions. Evidence we found indicates that the Trojan-horse mechanism really exists.

  10. Biosynthesized silver nanoparticles: are they effective antimicrobials?

    PubMed Central

    Peiris, Mudara K; Gunasekara, Chinthika P; Jayaweera, Pradeep M; Arachchi, Nuwan DH; Fernando, Neluka

    2017-01-01

    BACKGROUND Silver nanoparticles (AgNPs) are increasingly being used in medical applications. Therefore, cost effective and green methods for generating AgNPs are required. OBJECTIVES This study aimed towards the biosynthesis, characterisation, and determination of antimicrobial activity of AgNPs produced using Pseudomonas aeruginosa ATCC 27853. METHODS Culture conditions (AgNO3 concentration, pH, and incubation temperature and time) were optimized to achieve maximum AgNP production. The characterisation of AgNPs and their stability were evaluated by UV-visible spectrophotometry and scanning electron microscopy. FINDINGS The characteristic UV-visible absorbance peak was observed in the 420–430 nm range. Most of the particles were spherical in shape within a size range of 33–300 nm. The biosynthesized AgNPs exhibited higher stability than that exhibited by chemically synthesized AgNPs in the presence of electrolytes. The biosynthesized AgNPs exhibited antimicrobial activity against Escherichia coli, P. aeruginosa, Salmonella typhimurium, Staphylococcus aureus, methicillin-resistant S. aureus, Acinetobacter baumannii, and Candida albicans. MAIN CONCLUSION As compared to the tested Gram-negative bacteria, Gram-positive bacteria required higher contact time to achieve 100% reduction of colony forming units when treated with biosynthesized AgNPs produced using P. aeruginosa. PMID:28767978

  11. Femtosecond dynamics of monolayer MoS2-Ag nanoparticles hybrid probed at 532 nm

    NASA Astrophysics Data System (ADS)

    Xu, Xuefeng; Shi, Ying; Liu, Xiaochun; Sun, Mengtao

    2018-01-01

    In this communication, plasmon-exciton couplings of monolayer MoS2/Ag nanoparticles (NPs) hybrids with different sizes are investigated, using transient absorption spectra. Ultrafast dynamics of coupling interactions inside these hybrid structures are carefully examined at 532 nm, which can well interpret the apllication of plasmon-exciton coupling for the co-driven chemical reactions excited at 532 nm. Our experimental results can promote the deeper understanding on the physical mechanism of plasmon-excition interaction, and applications in different fields.

  12. Andrographolide-loaded nanoparticles for brain delivery: Formulation, characterisation and in vitro permeability using hCMEC/D3 cell line.

    PubMed

    Guccione, Clizia; Oufir, Mouhssin; Piazzini, Vieri; Eigenmann, Daniela Elisabeth; Jähne, Evelyn Andrea; Zabela, Volha; Faleschini, Maria Teresa; Bergonzi, Maria Camilla; Smiesko, Martin; Hamburger, Matthias; Bilia, Anna Rita

    2017-10-01

    Andrographolide (AG) is a major diterpenoid of the Asian medicinal plant Andrographis paniculata which has shown exciting pharmacological potential for the treatment of inflammation-related pathologies including neurodegenerative disorders. Conversely, the low bioavailability of AG still represents a limiting factor for its use. To overcome these limitations, AG was loaded into human serum albumin based nanoparticles (HSA NPs) and poly ethylcyanoacrylate nanoparticles (PECA NPs). HSA NPs were prepared by thermal (HSAT AG NPs) and chemical cross-linking (HSAC AG NPs), while PECA AG NPs were produced by emulsion-polymerization. NPs were characterized in terms of size, zeta (ζ)-potential, polydispersity, and release studies of AG. In addition, the ability of free AG and AG-loaded in PECA and HSAT NPs to cross the blood-brain barrier (BBB) was assessed using an in vitro BBB model based on human cerebral microvascular endothelial cell line (hCMEC/D3). For BBB drug permeability assays, a quantitative UPLC-MS/MS method for AG in Ringer HEPES buffer was developed and validated according to international regulatory guidelines for industry. Free AG did not permeate the BBB model, as also predicted by in silico studies. HSAT NPs improved by two-fold the permeation of AG while maintaining the integrity of the cell layer, while PECA NPs temporarily disrupted BBB integrity. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Cytokinin response in pepper plants (Capsicum annuum L.) exposed to silver nanoparticles.

    PubMed

    Vinković, Tomislav; Novák, Ondrej; Strnad, Miroslav; Goessler, Walter; Jurašin, Darija Domazet; Parađiković, Nada; Vrček, Ivana Vinković

    2017-07-01

    The increasing development of different nanomaterials, such as silver nanoparticles (AgNPs), and their practical use in agriculture and biotechnology has created a strong need for elucidations of biological effects and risk assessments of AgNPs in plants. This study was aimed to investigate AgNPs effects on metal uptake and their biodistribution in pepper plants as well as on morphological parameters and hormonal responses of the isoprenoid cytokinin (CK) family. In addition, the comparison of effects silver form, nanoparticles vs. ionic, has also been examined. To the best of our knowledge, this is the first study describing CK responses in plants exposed to metallic NPs. The obtained results indicate that both AgNPs and Ag + ions significantly increased total content of Ag + in pepper tissues in a dose-dependent manner and affected on plant development by decreasing both plant height and biomass in a similar way. This study evidenced for the first time the role of CKs in abiotic stress in plants caused by AgNPs. The hormonal analysis, conducted by an ultra-high performance liquid chromatography-electrospray tandem mass spectrometry, revealed a significant increase in total CKs in the leaves and also highlighted the importance of cis-zeatin type CKs in plants treated with AgNPs. Our observations suggest potential risks of AgNPs on plant ecosystems upon their release into the environment. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Green synthesis and antimicrobial activity of monodisperse silver nanoparticles synthesized using Ginkgo Biloba leaf extract

    NASA Astrophysics Data System (ADS)

    Ren, Yan-yu; Yang, Hui; Wang, Tao; Wang, Chuang

    2016-11-01

    Various parts of plants can be used as a raw material for the synthesis of nanoparticles, which is eco-friendly way and does not involve any harmful chemicals. In this project, Ginkgo biloba leaf, an abundantly available medicinal plant in China, was for the first time adopted as a reducing and stabilizing agent to synthesize smaller sized and stable silver nanoparticles (AgNPs). To improve the quality of AgNPs, the reduction was accelerated by changing the concentrations of initial Ag+ (0.02, 0.04, 0.06 and 0.08 mol/L) of the reaction mixture consisting of silver nitrate solution (AgNO3) and Ginkgo biloba leaf extract. At pH = 8 and lower AgNO3 concentration (0.02 mol/L), a colloid consisting of well-dispersed spherical nanoparticles was obtained. The synthesized nanocrystals were successfully characterized by UV-vis and XRD. TEM images revealed the size of the spherical AgNPs ranged between 10-16 nm. FTIR analysis revealed that biological macromolecules with groups of sbnd NH2, sbnd OH, and others were distributed on the surface of the nanoparticles. The biosynthesized AgNPs exhibited good antibacterial activities against gram-negative bacteria and gram-positive bacteria. Compared to traditional chemical methods, Ginkgo biloba leaf extract provides an easy green synthetical way. It is anticipated that the biosynthesized AgNPs can be used in areas such as cosmetics, foods and medical applications.

  15. Tuning the inflammatory response to silver nanoparticles via quercetin in Caco-2 (co-)cultures as model of the human intestinal mucosa.

    PubMed

    Martirosyan, Alina; Grintzalis, Konstantinos; Polet, Madeleine; Laloux, Laurie; Schneider, Yves-Jacques

    2016-06-24

    Interaction of nanoparticles with food matrix components may cause unpredictable health complications. Using an improved Caco-2 cell-based in vitro (co-)culture model the potential of quercetin as one of the major food flavonoids to alter the effect of silver nanoparticles (Ag-NPs) <20 nm in the human intestinal mucosa at real life concentrations was investigated. Ag-NPs (15-90 μg/ml) decreased cell viability and reduced thiol groups, induced oxidative/nitrosative stress and lipid peroxidation and led to activity changes of various antioxidant enzymes after 3h exposure. The contribution of Ag(+) ions within the concentrations released from nanoparticles was shown to be less important, compared to Ag-NPs. While leading to inflammatory response in the intestines, Ag-NPs, paradoxically, also showed a potential anti-infammatory effect manifested in down-regulated IL-8 levels. Quercetin, co-administered with Ag-NPs, led to a reduction of cytotoxicity, oxidative stress, and recovered metabolic activity of Caco-2 cells, suggesting the protective effects of this flavonoid against the harmful effect of Ag-NPs. Quercetin not only alleviated the effect of Ag-NPs on the gastrointestinal cells, but also demonstrated a potential to serve as a tool for reversible modulation of intestinal permeability. Copyright © 2016. Published by Elsevier Ireland Ltd.

  16. The effect of soil properties on the toxicity and bioaccumulation of Ag nanoparticles and Ag ions in Enchytraeus crypticus.

    PubMed

    Topuz, Emel; van Gestel, Cornelis A M

    2017-10-01

    Standard natural Lufa soils (2.2, 2.3 and 5M) with different organic carbon contents (0.67-1.61%) and pH CaCl2 (5.5-7.3) were spiked with ionic Ag (AgNO 3 ) and polyvinyl pyrrolidone (AgNP-PVP) and citrate (AgNP-Cit) coated Ag nanoparticles (NPs). Enchytraeus crypticus were exposed for 21 days to assess effects on survival and reproduction. Soil, pore water and animals were analyzed for Ag. AgNP-Cit had a strong increasing effect on soil pH, leading to high enchytraeid mortality at concentrations higher than 60-100mg Ag/kg dry soil which made it impossible to determine the influence of soil properties on its toxicity. LC50s were lower for AgNO 3 than for AgNP-PVP (92-112 and 335-425mg Ag/kg dry soil, respectively) and were not affected by soil properties. AgNO 3 and AgNP-PVP had comparable reproductive toxicity with EC50s of 26.9-75.2 and 28.2-92.3mg Ag/kg dry soil, respectively; toxicity linearly increased with decreasing organic carbon content of the soils but did not show a clear effect of soil pH. Ag uptake in the enchytraeids was higher at higher organic carbon content, but could not explain differences in toxicity between soils. This study indicates that the bioavailability of both ionic and nanoparticulate Ag is mainly affected by soil organic carbon, with little effect of soil pH. Copyright © 2017. Published by Elsevier Inc.

  17. Silver nanoparticles are broad-spectrum bactericidal and virucidal compounds

    PubMed Central

    2011-01-01

    The advance in nanotechnology has enabled us to utilize particles in the size of the nanoscale. This has created new therapeutic horizons, and in the case of silver, the currently available data only reveals the surface of the potential benefits and the wide range of applications. Interactions between viral biomolecules and silver nanoparticles suggest that the use of nanosystems may contribute importantly for the enhancement of current prevention of infection and antiviral therapies. Recently, it has been suggested that silver nanoparticles (AgNPs) bind with external membrane of lipid enveloped virus to prevent the infection. Nevertheless, the interaction of AgNPs with viruses is a largely unexplored field. AgNPs has been studied particularly on HIV where it was demonstrated the mechanism of antiviral action of the nanoparticles as well as the inhibition the transmission of HIV-1 infection in human cervix organ culture. This review discusses recent advances in the understanding of the biocidal mechanisms of action of silver Nanoparticles. PMID:21812950

  18. Molecular aspects of metal oxide nanoparticle (MO-NPs) mediated pharmacological effects.

    PubMed

    Tuli, Hardeep Singh; Kashyap, Dharambir; Bedi, Simranjeet Kaur; Kumar, Pardeep; Kumar, Gaurav; Sandhu, Sardul Singh

    2015-12-15

    Metal oxide nanoparticles (MO-NPs) are the multidisciplinary nano-scaled molecules which are being used in the diagnosis and treatment of the challenging diseases including cancer. Evidence suggest that antimicrobial formulations in the form of MO-NPs can be possibly used as effective antimicrobial agents. In addition, MO-NPs are known to target various cellular signaling pathways associated with apoptosis, angiogenesis, metastasis and inflammation of cancer. In combination with other chemotherapeutic/anticancer agents, MO-NPs not only increase their bioavailability and efficacy but also lower down the requirement of active dosages. To date, to our knowledge there is no single comprehensive report on cellular and molecular interactions of MO-NPs which have been well elaborated in this review. Also we highlight various action mechanisms through which MO-NPs act as antimicrobial, anticancer, antioxidant and anti-inflammatory agents. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Synthesis of silver nanoparticles stabilized with C-phycocyanin and for fluorimetric detection of copper ions

    NASA Astrophysics Data System (ADS)

    Wei, Nana; Hou, Yanhua; Lu, Zongbao; Yu, Huatong; Wang, Quanfu

    2018-01-01

    In this study, C-phycocyanin as protective agent, AgNO3 as raw material and NaBH4 as reducing agent synthesized C-phycocyanin-Ag nanoparticles (PC-AgNPs). The synthesis conditions of PC-AgNPs were determined by optimization. The maximum UV absorption peak of PC-AgNPs at 400 nm. The fluorescence excitation wavelength was 580 nm and the emission wavelength was 625 nm. PC-AgNPs was spherical in transmission electron microscope and the particles sizes were about 10-25 nm. In addition, fluorescence quenching was observed after adding copper ions to PC-AgNPs, which indicated that PC-AgNPs has potential applications in the detection of copper ions in diverse water environment.

  20. Colorimetric detection of glucose based on gold nanoparticles coupled with silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Gao, Yan; Wu, Yiting; Di, Junwei

    2017-02-01

    We have coupled gold nanoparticles (AuNPs) with silver nanoparticles (AgNPs) to assemble a plasmonic sensing platform for colorimetric detection of glucose. In this system, small AuNPs ( 4 nm) can act as glucose oxidase (GOD) mimic enzyme to catalytically oxidize glucose in the presence of oxygen, producing hydrogen peroxide, which dissolves AgNPs to lead the color changes. Glucose can be detected not only by naked eyes (from yellow to red) but also by spectrophotometer in the concentration range of 5-70 μM, with detection limit of 3 μM. More importantly, we found that L-cysteine added in the system can markedly improve the selectivity for the detection of glucose. The proposed method was used to application for the detection of glucose in human serum with satisfactory results. This system is simple and low cost without using any enzymes and organic chromogenic agents.

  1. Green synthesis of silver nanoparticles by Ricinus communis var. carmencita leaf extract and its antibacterial study

    NASA Astrophysics Data System (ADS)

    Ojha, Sunita; Sett, Arghya; Bora, Utpal

    2017-09-01

    In this study, we report synthesis of silver nanoparticles (RcAgNPs) from silver nitrate solution using methanolic leaf extract of Ricinus communis var. carmencita. The polyphenols present in the leaves reduce Ag++ ions to Ag0 followed by a color change. Silver nanoparticle formation was ensured by surface plasmon resonance between 400 nm to 500 nm. Crystallinity of the synthesized nanoparticles was confirmed by UHRTEM, SAED and XRD analysis. The capping of phytochemicals and thermal stability of RcAgNPs were assessed by FTIR spectra and TGA analysis, respectively. It also showed antibacterial activity against both gram positive and gram negative strains. RcAgNPs were non-toxic against normal cell line (mouse fibroblast cell line L929) at lower concentrations (80 µg ml-1).

  2. Transformation of Four Silver/Silver Chloride Nanoparticles during Anaerobic Treatment of Wastewater and Post-processing of Sewage Sludge

    EPA Science Inventory

    The increasing use of silver (Ag) nanoparticles [containing either elemental Ag (Ag-NPs) or AgCl (AgCl-NPs)] in commercial products such as textiles will most likely result in these materials reaching wastewater treatment plants. Previous studies indicate that a conversion of Ag-...

  3. Multicolor Layer-by-Layer films using weak polyelectrolyte assisted synthesis of silver nanoparticles

    PubMed Central

    2013-01-01

    In the present study, we show that silver nanoparticles (AgNPs) with different shape, aggregation state and color (violet, green, orange) have been successfully incorporated into polyelectrolyte multilayer thin films using the layer-by-layer (LbL) assembly. In order to obtain colored thin films based on AgNPs is necessary to maintain the aggregation state of the nanoparticles, a non-trivial aspect in which this work is focused on. The use of Poly(acrylic acid, sodium salt) (PAA) as a protective agent of the AgNPs is the key element to preserve the aggregation state and makes possible the presence of similar aggregates (shape and size) within the LbLcolored films. This approach based on electrostatic interactions of the polymeric chains and the immobilization of AgNPs with different shape and size into the thin films opens up a new interesting perspective to fabricate multicolornanocomposites based on AgNPs. PMID:24148227

  4. Characterization, antibacterial, antioxidant, antidiabetic, anti-inflammatory and antityrosinase activity of green synthesized silver nanoparticles using Calophyllum tomentosum leaves extract

    NASA Astrophysics Data System (ADS)

    Govindappa, M.; Hemashekhar, B.; Arthikala, Manoj-Kumar; Ravishankar Rai, V.; Ramachandra, Y. L.

    2018-06-01

    The current research study is to develop an easy and eco-friendly method for the synthesis of AgNPs using aqueous leaf extract of Calophyllum tomentosum (CtAgNPs) and evaluated the extract to know the effects of anti-bacterial, antioxidant, anti-diabetic, anti-inflammatory and anti-tyrosinase activity. Using UV-vis spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) characterized the Calophyllum tomentosum mediated silver nanoparticles. The leaf extract of C. tomentosum yielded flavonoids, saponins, tannins, alkaloids, glycosides, phenols, terpenoids and coumarins. AgNPs formation was confirmed by UV-vis spectra at 438 nm. Crystalline structure with a face centered cubic (fcc) of AgNPs was observed in XRD. FTIR had shown that the phytochemicals were responsible for the reduction and capping material of silver nanoparticles. The size and shape of the AgNPs were determined using SEM. From EDX study analysed the strong absorption property of AgNPs. The CtAgNPs have showed significant antibacterial activity on multi drug resistance bacteria. The CtAgNPs had shown strong antioxidant (DPPH, H2O2 scavenging, nitric oxide scavenging power, reducing power) activities. The CtAgNPs had strongly inhibited the α-glucosidase and DPPIV compared to α-amylase. The CtAgNPs exhibited strong anti-inflammatory activity (albumin denaturation, membrane stabilization, heat haemolytic, protein inhibitory, lipoxygenase, xanthine oxidase) and tyrosinase inhibitory activity. To our best knowledge, this is the first attempt on the synthesis of silver nanoparticles using Calophyllum tomentosum leaves extract. Hence, to validate our results the in vivo studies at molecular level are needed to develop an antioxidant, anti-diabetic and anti-inflammatory agent.

  5. Rapid biosynthesis and characterization of silver nanoparticles: an assessment of antibacterial and antimycotic activity

    NASA Astrophysics Data System (ADS)

    Kanawaria, Sajjan Kumar; Sankhla, Aryan; Jatav, Pradeep Kumar; Yadav, Raghvendra Singh; Verma, Kumar Sambhav; Velraj, Parthiban; Kachhwaha, Sumita; Kothari, Shanker Lal

    2018-04-01

    Bioassisted synthesis provides a facile, convenient, and promising approach to produce many inorganic nanostructures. Herein, we report a rapid biosynthesis of silver nanoparticles (AgNPs) using Thuja occidentalis (L.) leaf extract with an emphasis on their antibacterial and antimycotic activity. Interestingly, the synthesis of AgNPs was completed in a short duration of 35-40 min. The electron micrographs showed AgNPs with particles < 30 nm in size. A diffusive absorption band around 430 nm confirmed the polydispersive nature of biosynthesized AgNPs. An additional absorption peak at 256 nm suggested the presence of biomolecules in the reaction mixture in addition to AgNPs. The different bands corresponding to ring compounds, amines, and carbonyl groups in the FT-IR spectra of biosynthesized AgNPs confirmed the presence of terpenes and terpenoids on AgNP surface post-reduction. The encapsulation and stabilization of AgNPs by organic layer was visible from the TEM images. Thus, these organic compounds present in the extract were responsible for first the reduction of precursor salts into AgNPs and second to drape around the particles preventing agglomeration. The AgNPs were effective against strains of Escherichia coli, Pseudomonas putida, and Bacillus subtilis. An AgNP solution with 30 µg/ml concentration arrested the growth of bacterial strains making a zone of inhibition > 15 mm. The antimycotic activity against Aspergillus niger, Fusarium spp., and Alternaria alternata species increased monotonically with nanoparticle concentration in the growth media. A 10 ppm solution of AgNP was detrimental to fungal growth. Thus, the technique provides an avenue to synthesize antibiotic AgNPs without use of other external agents.

  6. Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity

    NASA Astrophysics Data System (ADS)

    Sadeghi, Babak; Rostami, Amir; Momeni, S. S.

    2015-01-01

    In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods.

  7. Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity.

    PubMed

    Sadeghi, Babak; Rostami, Amir; Momeni, S S

    2015-01-05

    In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446 nm in the UV-visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27 nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (111), (200), (220) and (311) Bragg's reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Determination of dextrose in peritoneal dialysis solution by localized surface plasmon resonance technique based on silver nanoparticles formation

    NASA Astrophysics Data System (ADS)

    Masrournia, Mahboube; Montazarolmahdi, Maliheh; Sani, Faramarz Aliasghari

    2017-07-01

    Determination of dextrose in peritoneal dialysis with a method based on silver nanoparticles (AgNPs) formation was investigated. In a green chemistry method, silver nanoparticles (AgNPs) were synthesized in the natural polymeric matrix of gelatin. The nanoparticles were characterized with UV-Vis spectroscopy and transmission electron microscopy (TEM). Absorbance signal of AgNPs could be applied to determine the various concentrations of dextrose solutions. Drop wise and ultrasonic methods were used and compared with each other. The dynamic range of methods with limit of detection and relative standard deviations were obtained. Results for real sample (peritoneal dialysis) were satisfied.

  9. Synthesis, characterization, and thermal stability of SiO2/TiO2/CR-Ag multilayered nanostructures

    NASA Astrophysics Data System (ADS)

    Díaz, Gabriela; Chang, Yao-Jen; Philipossian, Ara

    2018-06-01

    The controllable synthesis and characterization of novel thermally stable silver-based particles are described. The experimental approach involves the design of thermally stable nanostructures by the deposition of an interfacial thick, active titania layer between the primary substrate (SiO2 particles) and the metal nanoparticles (Ag NPs), as well as the doping of Ag nanoparticles with an organic molecule (Congo Red, CR). The nanostructured particles were composed of a 330-nm silica core capped by a granular titania layer (10 to 13 nm in thickness), along with monodisperse 5 to 30 nm CR-Ag NPs deposited on top. The titania-coated support (SiO2/TiO2 particles) was shown to be chemically and thermally stable and promoted the nucleation and anchoring of CR-Ag NPs, which prevented the sintering of CR-Ag NPs when the structure was exposed to high temperatures. The thermal stability of the silver composites was examined by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Larger than 10 nm CR-Ag NPs were thermally stable up to 300 °C. Such temperature was high enough to destabilize the CR-Ag NPs due to the melting point of the CR. On the other hand, smaller than 10 nm Ag NPs were stable at temperatures up to 500 °C because of the strong metal-metal oxide binding energy. Energy dispersion X-ray spectroscopy (EDS) was carried out to qualitatively analyze the chemical stability of the structure at different temperatures which confirmed the stability of the structure and the existence of silver NPs at temperatures up to 500 °C.

  10. Use of electrothermal atomic absorption spectrometry for size profiling of gold and silver nanoparticles.

    PubMed

    Panyabut, Teerawat; Sirirat, Natnicha; Siripinyanond, Atitaya

    2018-02-13

    Electrothermal atomic absorption spectrometry (ETAAS) was applied to investigate the atomization behaviors of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) in order to relate with particle size information. At various atomization temperatures from 1400 °C to 2200 °C, the time-dependent atomic absorption peak profiles of AuNPs and AgNPs with varying sizes from 5 nm to 100 nm were examined. With increasing particle size, the maximum absorbance was observed at the longer time. The time at maximum absorbance was found to linearly increase with increasing particle size, suggesting that ETAAS can be applied to provide the size information of nanoparticles. With the atomization temperature of 1600 °C, the mixtures of nanoparticles containing two particle sizes, i.e., 5 nm tannic stabilized AuNPs with 60, 80, 100 nm citrate stabilized AuNPs, were investigated and bimodal peaks were observed. The particle size dependent atomization behaviors of nanoparticles show potential application of ETAAS for providing size information of nanoparticles. The calibration plot between the time at maximum absorbance and the particle size was applied to estimate the particle size of in-house synthesized AuNPs and AgNPs and the results obtained were in good agreement with those from flow field-flow fractionation (FlFFF) and transmission electron microscopy (TEM) techniques. Furthermore, the linear relationship between the activation energy and the particle size was observed. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Silver nanoparticles: correlating nanoparticle size and cellular uptake with genotoxicity

    PubMed Central

    Butler, Kimberly S.; Peeler, David J.; Casey, Brendan J.; Dair, Benita J.; Elespuru, Rosalie K.

    2015-01-01

    The focus of this research was to develop a better understanding of the pertinent physico-chemical properties of silver nanoparticles (AgNPs) that affect genotoxicity, specifically how cellular uptake influences a genotoxic cell response. The genotoxicity of AgNPs was assessed for three potential mechanisms: mutagenicity, clastogenicity and DNA strand-break-based DNA damage. Mutagenicity (reverse mutation assay) was assessed in five bacterial strains of Salmonella typhimurium and Echerichia coli, including TA102 that is sensitive to oxidative DNA damage. AgNPs of all sizes tested (10, 20, 50 and 100nm), along with silver nitrate (AgNO3), were negative for mutagenicity in bacteria. No AgNPs could be identified within the bacteria cells using transmission electron microscopy (TEM), indicating these bacteria lack the ability to actively uptake AgNPs 10nm or larger. Clastogenicity (flow cytometry-based micronucleus assay) and intermediate DNA damage (DNA strand breaks as measured in the Comet assay) were assessed in two mammalian white blood cell lines: Jurkat Clone E6-1 and THP-1. It was observed that micronucleus and Comet assay end points were inversely correlated with AgNP size, with smaller NPs inducing a more genotoxic response. TEM results indicated that AgNPs were confined within intracellular vesicles of mammalian cells and did not penetrate the nucleus. The genotoxicity test results and the effect of AgNO3 controls suggest that silver ions may be the primary, and perhaps only, cause of genotoxicity. Furthermore, since AgNO3 was not mutagenic in the gram-negative bacterial Ames strains tested, the lack of bacterial uptake of the AgNPs may not be the major reason for the lack of genotoxicity observed. PMID:25964273

  12. Optimization of process variables for the biosynthesis of silver nanoparticles by Aspergillus wentii using statistical experimental design

    NASA Astrophysics Data System (ADS)

    Biswas, Supratim; Mulaba-Bafubiandi, Antoine F.

    2016-12-01

    The present scientific endeavour focuses on the optimization of process parameters using central composite design towards development of an efficient technique for the biosynthesis of silver nanoparticles. The combined effects of three process variables (days of fermentation, duration of incubation, concentration of AgNO3) upon extracellular biological synthesis of silver nanoparticles (AgNPs) by Aspergillus wentii NCIM 667 were studied. A single absorption peak at 455 nm confirming the presence of silver nanoparticles was observed in the UV-visible spectrophotometric graph. Using Fourier transform infrared spectroscopic analysis the presence of proteins as viable reducing agents for the formation AgNPs was recorded. High resolution transmission electron microscopy showed the realization of spherically shaped AgNPs of size 15-40 nm. Biologically formed AgNPs revealed higher antimicrobial activity against gram-negative than gram-positive bacterial strains. We present the enumeration of the properties of biosynthesized nanoparticles which exhibit photocatalysis exhausting an organic dye, the methyl orange, upon exposure to sunlight thereby accomplishing the degradation of almost (88%) the methyl orange dye within 5 h.

  13. Green production of microalgae-based silver chloride nanoparticles with antimicrobial activity against pathogenic bacteria.

    PubMed

    da Silva Ferreira, Veronica; ConzFerreira, Mateus Eugenio; Lima, Luís Maurício T R; Frasés, Susana; de Souza, Wanderley; Sant'Anna, Celso

    2017-02-01

    Silver nanoparticles are powerful antimicrobial agents. Here, the synthesis of silver chloride nanoparticles (AgCl-NPs) was consistently evidenced from a commercially valuable microalgae species, Chlorella vulgaris. Incubation of C. vulgaris conditioned medium with AgNO 3 resulted in a medium color change to yellow/brown (with UV-vis absorbance at 415nm), indicative of silver nanoparticle formation. Energy-dispersive X-ray spectroscopy (EDS) of purified nanoparticles confirmed the presence of both silver and chlorine atoms, and X-ray diffraction (XRD) showed the typical pattern of cubic crystalline AgCl-NPs. Transmission electron microscopy (TEM) showed that most particles (65%) were spherical, with average diameter of 9.8±5.7nm. Fourier transform infrared spectroscopy (FTIR) of purified nanoparticle fractions suggested that proteins are the main molecular entities involved in AgCl-NP formation and stabilization. AgCl-NPs (from 10μg/mL) decreased by 98% the growth of Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae bacterial pathogens, and had a dose-dependent effect on cell viability, which was measured by automated image-based high content screening (HCS). Ultrastructural analysis of treated bacteria by TEM revealed the abnormal arrangement of the chromosomal DNA. Our findings strongly indicated that the AgCl-NPs from C. vulgaris conditioned medium is a promising 'green' alternative for biomedical application as antimicrobials. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Toxicity, Bioaccumulation and Biotransformation of Silver Nanoparticles in Marine Organisms

    EPA Science Inventory

    The toxicity, bioaccumulation and biotransformation of citrate and polyvinylpyrrolidone (PVP) capped silver nanoparticles (NPs) (AgNP-citrate and AgNP-PVP) and titanium dioxide (TiO2) NPs in marine organisms via marine sediment exposure were investigated. Results from 7-d sedimen...

  15. Isotopically modified silver nanoparticles to assess nanosilver bioavailability and toxicity at environmentally relevant exposures

    USGS Publications Warehouse

    Croteau, Marie-Noële; Dybowska, Agnieszka D.; Luoma, Samuel N.; Misra, Superb K.; Valsami-Jones, Eugenia

    2014-01-01

    A major challenge in understanding the environmental implications of nanotechnology lies in studying nanoparticle uptake in organisms at environmentally realistic exposure concentrations. Typically, high exposure concentrations are needed to trigger measurable effects and to detect accumulation above background. But application of tracer techniques can overcome these limitations. Here we synthesised, for the first time, citrate-coated Ag nanoparticles using Ag that was 99.7 % 109Ag. In addition to conducting reactivity and dissolution studies, we assessed the bioavailability and toxicity of these isotopically modified Ag nanoparticles (109Ag NPs) to a freshwater snail under conditions typical of nature. We showed that accumulation of 109Ag from 109Ag NPs is detectable in the tissues of Lymnaea stagnalis after 24-h exposure to aqueous concentrations as low as 6 ng L–1 as well as after 3 h of dietary exposure to concentrations as low as 0.07 μg g–1. Silver uptake from unlabelled Ag NPs would not have been detected under similar exposure conditions. Uptake rates of 109Ag from 109Ag NPs mixed with food or dispersed in water were largely linear over a wide range of concentrations. Particle dissolution was most important at low waterborne concentrations. We estimated that 70 % of the bioaccumulated 109Ag concentration in L. stagnalis at exposures –1 originated from the newly solubilised Ag. Above this concentration, we predicted that 80 % of the bioaccumulated 109Ag concentration originated from the 109Ag NPs. It was not clear if agglomeration had a major influence on uptake rates.

  16. Effect of capping agents on the cytotoxicity of silver nanoparticles in human normal and cancer skin cell lines

    NASA Astrophysics Data System (ADS)

    Netchareonsirisuk, Ponsawan; Puthong, Songchan; Dubas, Stephan; Palaga, Tanapat; Komolpis, Kittinan

    2016-11-01

    Silver nanoparticles (AgNPs) are among the most widely used nanomaterials in medical and consumer products. However, safety in the uses of AgNPs is still controversial. The toxicity of AgNPs toward various cell types has been reported to depend on the surface properties of the nanoparticles. In this study, the effect of AgNPs with the average size of 5-15 nm on the viability of the CCD-986SK human normal skin fibroblast cell line and A375 human malignant melanoma cell line was evaluated. Comparative toxicity studies, based on MTT assay, were performed by using either sodium alginate or poly (4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA) as capping agent in the nanoparticle preparation. The cytotoxicity tests revealed that AgNO3 alone was highly toxic to both cell types while both alginate and PSSMA alone were not toxic. AgNPs capped with alginate were selectively toxic to the cancer cell line but not to the normal cell line while AgNPs capped with PSSMA were toxic to both cancer and normal cell lines. Judging from the 50 % inhibition concentration (IC50), it was found that the cancer cell line was more sensitive to AgNPs than the normal cell line. Study on the mode of cell death by annexin V and propidium iodide staining revealed that AgNPs induced more apoptotic cell death (84-90 %) than necrosis (8-12 %) in the skin cancer cell line. These results suggest that the toxicity of AgNPs depended on the type of capping agent and the type of cell line.

  17. Detection of silver nanoparticles in parsley by solid sampling high-resolution-continuum source atomic absorption spectrometry.

    PubMed

    Feichtmeier, Nadine S; Leopold, Kerstin

    2014-06-01

    In this work, we present a fast and simple approach for detection of silver nanoparticles (AgNPs) in biological material (parsley) by solid sampling high-resolution-continuum source atomic absorption spectrometry (HR-CS AAS). A novel evaluation strategy was developed in order to distinguish AgNPs from ionic silver and for sizing of AgNPs. For this purpose, atomisation delay was introduced as significant indication of AgNPs, whereas atomisation rates allow distinction of 20-, 60-, and 80-nm AgNPs. Atomisation delays were found to be higher for samples containing silver ions than for samples containing silver nanoparticles. A maximum difference in atomisation delay normalised by the sample weight of 6.27 ± 0.96 s mg(-1) was obtained after optimisation of the furnace program of the AAS. For this purpose, a multivariate experimental design was used varying atomisation temperature, atomisation heating rate and pyrolysis temperature. Atomisation rates were calculated as the slope of the first inflection point of the absorbance signals and correlated with the size of the AgNPs in the biological sample. Hence, solid sampling HR-CS AAS was proved to be a promising tool for identifying and distinguishing silver nanoparticles from ionic silver directly in solid biological samples.

  18. Synthesis colloidal Kyllinga brevifolia-mediated silver nanoparticles at different temperature for methylene blue removal

    NASA Astrophysics Data System (ADS)

    Isa, Norain; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

    2017-09-01

    Metallic nanoparticles are well known of having wide applications in various fields such as, catalysis, electronics, energy, chemistry and medicine due to its unique physico-chemical properties. In this study, nanocatalyst Kyllinga brevifolia-mediated silver nanoparticles (AgNPs) were prepared by reduction of silver nitrate using aqueous extract of Kyllinga brevifolia at different temperature. The formations of AgNPs were monitored using UV-visible spectroscopy. Transmission electron microscope (TEM) results reveal that the AgNPs well dispersed with average particle size are 22.34 and 6.73 nm for synthesized at room temperature and cold temperature respectively. The biomolecules present in the Kyllinga brevifolia aqueous extract responsible for the formation of AgNPs were identified using Fourier transform infrared (FTIR). Our AgNPs performed excellent catalytic activity in degradation of methylene blue (MB) dyes via electron relay effect. MB is toxic to ecological system and also has carcinogenic properties. The AgNPs nanocatalysts synthesized in this study are highly dispersed, quasi-spherical and due to their size in nanoscale, they have shown effectiveness for degradation of MB dyes. More importantly, our AgNPs were prepared using biomolecules as capping and reducing agent, which make our product "greener" than available AgNPs that are commonly prepared using hydrazine and borohydride; which are harmful substances to human and environment. Not only the AgNPs can act as nanocatalyst for degradation of MB, they can also be expected to degrade other types of toxic dyes used in textiles industry.

  19. Quantitative determination of melamine in milk using Ag nanoparticle monolayer film as SERS substrate

    NASA Astrophysics Data System (ADS)

    Li, Ruoping; Yang, Jingliang; Han, Junhe; Liu, Junhui; Huang, Mingju

    2017-04-01

    A Raman method employing silver nanoparticle (Ag NP) monolayer film as Surface-enhanced Raman Scattering (SERS) substrate was presented to rapidly detect melamine in milk. The Ag NPs with 80 nm diameter were modified by polyvinylpyrrolidone to improve their uniformity and chemical stability. The treatment procedure of liquid milk required only addition of acetic acid and centrifugation, and required time is less than 15 min. The Ag NP monolayer film significantly enhanced Raman signal from melamine and allowed experimentally reproducible determination of the melamine concentration. A good linear relationship (R2=0.994) between the concentration and Raman peak intensity of melamine at 681 cm-1 was obtained for melamine concentrations between 0.10 mg L-1 and 5.00 mg L-1. This implies that this method can detect melamine concentrations below 1.0 mg L-1, the concentration currently considered unsafe.

  20. Biosynthesis of silver nanoparticles by using Ganoderma-mushroom extract

    NASA Astrophysics Data System (ADS)

    Ekar, S. U.; Khollam, Y. B.; Koinkar, P. M.; Mirji, S. A.; Mane, R. S.; Naushad, M.; Jadhav, S. S.

    2015-03-01

    Present study reports the biochemical synthesis of silver nanoparticles (Ag-NPs) from aqueous medium by using the extract of medicinal mushroom Ganoderma, as a reducing and stabilizing agents. The Ag-NPs are prepared at room temperature by the reduction of Ag+ to Ag in aqueous solution of AgNO3. The resultant particles are characterized by using UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) measurement techniques. The formation of Ag-NPs is confirmed by recording the UV-visible absorption spectra for surface plasmon resonance (SPR) where peak around 427 nm. The prominent changes observed in FTIR spectra supported the reduction of Ag+ to Ag. The morphological features of Ag-NPs are evaluated from HRTEM. The spherical Ag-NPs are observed in transmission electron microscopy (TEM) studies. The particle size distribution is found to be nearly uniform with average particle size of 2 nm. The Ag-NPs aged for 15, 30, 60 and 120 days showed no profound effect on the position of SPR peak in UV-visible studies, indicating the protecting/capping ability of medicinal mushroom Ganoderma in the synthesis of Ag-NPs.

  1. Effect of Ag nanoparticles deposition on photocatalytic activity of Ag{sub 2}SO{sub 3}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Xuan, E-mail: xzhang@dhu.edu.cn; Wang, Qi; Hu, Jin-Wen

    Highlights: • Ag{sub 2}SO{sub 3} was developed as novel photocatalyst. • The effect of Ag nanoparticles deposition on photocatalytic activity was investigated. • The activation and deactivation mechanism was proposed. - Abstract: A novel photocatalyst Ag{sub 2}SO{sub 3} was prepared and the effect of Ag nanoparticles, photo-deposited on the surface of Ag{sub 2}SO{sub 3}, on its photocatalytic activity was investigated. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–vis diffuse reflection spectroscopy (DRS). The photocatalytic activity was evaluated by photo-degradation of rhodamine B dye under UV light irradiation. It was found that the photocatalyticmore » activity of Ag{sub 2}SO{sub 3} was initially enhanced with deposition of Ag nanoparticles, but subsequently declined with Ag nanoparticles overloaded. The possible mechanism was proposed based on experimental results. These findings may contribute to developing novel photocatalysts and understanding of fundamentals of Ag-based photocatalytic materials.« less

  2. Physicochemical characterization of silver nanoparticles synthesize using Aloe Vera (Aloe barbadensis)

    NASA Astrophysics Data System (ADS)

    Kuponiyi, Abiola; Kassama, Lamin; Kukhtareva, Tatiana

    2014-08-01

    Production of silver nanoparticles (AgNPs) using different biological methods is gaining recognition due to their multiple applications. Although, several physical and chemical methods have been used for the synthesis and stabilizing of AgNPs, yet, a green chemistry method is preferable because it is cost effective and environmentally friendly. The synthesis was done using Aloe Vera (AV) extract because it has chemical compounds such as "Antrokinon" that are known for its antibacterial, antivirus and anticancer properties. We hypothesize that AV extract can produce a stable nanoparticles within the 100 nm range and be biologically active. The biological compounds were extracted from AV skin with water and ethanol which was used as the reduction agent for the synthesis of nanoparticles. The biological extract and AgNO3 were blended and heated to synthesize AgNPs. The reaction process was monitored using UV-Visible spectroscopy. Fourier Transfer Infrared spectroscopy (FTIR) was used for the characterization of biological compounds and their substituent groups before and after the reaction process. Dynamic Light scattering (DLS) method was used to characterize particle size of AgNPs and their biomolecular stability. Results showed that biological compounds such as aliphatic amines, alkenes (=C-H), alkanes (C-H), alcohol (O-H) and unsaturated esters(C-O), which has an average particle size of 109 and 215.8 nm and polydispersity index of 0.451 and 0.375 for ethanol and water extract, respectively. According to TEM measurements the size of AgNPs are in the range 5-20 nm The results suggested that ethanol derived AgNPs contained higher yield of organic compounds, thus has better solubility power than water. Ag NPs can be used to control salmonella in poultry industry.

  3. Mycosynthesis of silver nanoparticles using extract of endophytic fungi, Penicillium species of Glycosmis mauritiana, and its antioxidant, antimicrobial, anti-inflammatory and tyrokinase inhibitory activity

    NASA Astrophysics Data System (ADS)

    Govindappa, M.; Farheen, H.; Chandrappa, C. P.; Channabasava; Rai, Ravishankar V.; Raghavendra, Vinay B.

    2016-09-01

    Silver nanoparticles were synthesized using endophytic fungal species, Penicillium species from Glycosmis mautitiana. Phytochemicals, namely tannins, saponins, terpenoids and flavonoids, were identified in Penicillium species extracts, and act as agents of reducing and capping in the conversion of silver nanoparticles into nanoparticles. Using SEM, UV-spectroscopy and XRD, the Penicillium species silver nanoparticles (PsAgNPs) were characterized. The PsAgNPs are shown to be strong antioxidants (DDPH and FRAP), have demonstrated anti-inflammatory properties by three different methods in vitro and strongly inhibited the activity of xanthine oxidase, lipoxygenase and tyrosine kinase. E. coli and P. aeruginosa bacterial species were strongly inhibited by PsAgNPs activity at maximum levels and SEM picture of P. aeruginosa confirms these effects and that they were shrunken due to the toxic effect of PsAgNPs.

  4. Biosynthesis of silver nanoparticles using Sida acuta extract for antimicrobial actions and corrosion inhibition potential.

    PubMed

    Idrees, Muhammad; Batool, Saima; Kalsoom, Tanzila; Raina, Sadaf; Sharif, Hafiz Muhammad Adeel; Yasmeen, Summera

    2018-02-12

    Nanotechnology exhibits a multidisciplinary area and gained interests for researchers. Nanoparticles produced via physical and chemical methods affects ecosystem drastically. Green synthesis is the charming technique that is inexpensive and safe for the environment. This study aimed to explore the antibacterial actions of as-synthesized silver nanoparticles (Ag-NPs) against Escherichia coli, Staphylococcus aureus and Streptococcus faecalis. Also, the anti-corrosion actions confirmed that the Ag-NPs proved as good inhibitors. In this way, Ag-NPs were prepared via biosynthesis technique by consuming the ground leaves and stem of 'Sida acuta' as a capping agent. The Ag-NPs were formed by irradiation of the aqueous solution of silver nitrate (AgNO 3 ) with extract of S. acuta stem and leaves. The as-synthesized reaction mixture of Ag-NPs was found to exhibit an absorbance band at 446-447 nm, by an UV/VIS spectrophotometer, which is a characteristic of Ag-NPs due to the surface plasmon resonance absorption band. The X-ray diffraction and transmission electron microscopy (TEM) were used for the confirmation of Ag-NPs' variety dimension, morphology and dispersion. The infrared spectra confirmed the bio-fabrication of the Ag-NPs displayed the existence of conceivable functional groups responsible for the bio-reduction and capping. The antimicrobial actions were measured and the zone of inhibition was compared with standard antibiotics.

  5. Biogenic Silver Nanoparticles by Gelidiella acerosa Extract and their Antifungal Effects

    PubMed Central

    Vivek, Marimuthu; Kumar, Palanisamy Senthil; Steffi, Sesurajan; Sudha, Sellappa

    2011-01-01

    The synthesis, characterization and application of biologically synthesized nanomaterials are an important aspect in nanotechnology. The present study deals with the synthesis of silver nanoparticles (Ag-NPs) using the aqueous extract of red seaweed Gelidiella acerosa as the reducing agent to study the antifungal activity. The formation of Ag-NPs was confirmed by UV-Visible Spectroscopy, X-Ray Diffraction (XRD) pattern, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The synthesized Ag-NPs was predominately spherical in shape and polydispersed. Fourier Transform Infra-Red (FT-IR) spectroscopy analysis showed that the synthesized nano-Ag was capped with bimolecular compounds which are responsible for reduction of silver ions. The antifungal effects of these nanoparticles were studied against Humicola insolens (MTCC 4520), Fusarium dimerum (MTCC 6583), Mucor indicus (MTCC 3318) and Trichoderma reesei (MTCC 3929). The present study indicates that Ag-NPs have considerable antifungal activity in comparison with standard antifungal drug, and hence further investigation for clinical applications is necessary. PMID:23408653

  6. Controlled evaluation of silver nanoparticle dissolution using atomic force microscopy.

    PubMed

    Kent, Ronald D; Vikesland, Peter J

    2012-07-03

    Incorporation of silver nanoparticles (AgNPs) into an increasing number of consumer products has led to concern over the potential ecological impacts of their unintended release to the environment. Dissolution is an important environmental transformation that affects the form and concentration of AgNPs in natural waters; however, studies on AgNP dissolution kinetics are complicated by nanoparticle aggregation. Herein, nanosphere lithography (NSL) was used to fabricate uniform arrays of AgNPs immobilized on glass substrates. Nanoparticle immobilization enabled controlled evaluation of AgNP dissolution in an air-saturated phosphate buffer (pH 7.0, 25 °C) under variable NaCl concentrations in the absence of aggregation. Atomic force microscopy (AFM) was used to monitor changes in particle morphology and dissolution. Over the first day of exposure to ≥10 mM NaCl, the in-plane AgNP shape changed from triangular to circular, the sidewalls steepened, the in-plane radius decreased by 5-11 nm, and the height increased by 6-12 nm. Subsequently, particle height and in-plane radius decreased at a constant rate over a 2-week period. Dissolution rates varied linearly from 0.4 to 2.2 nm/d over the 10-550 mM NaCl concentration range tested. NaCl-catalyzed dissolution of AgNPs may play an important role in AgNP fate in saline waters and biological media. This study demonstrates the utility of NSL and AFM for the direct investigation of unaggregated AgNP dissolution.

  7. Transport and fate of engineered silver nanoparticles in aquifer media

    NASA Astrophysics Data System (ADS)

    Adrian, Y.; Schneidewind, U.; Azzam, R.

    2016-12-01

    Engineered silver nanoparticles (AgNPs) are used in various consumer and medical products due to their antimicrobial properties. Their transport behavior in the environment is still under investigation. Previous studies have been focusing on the transport of AgNPs in test systems with pure quartz sand or top soil materials, but studies investigating aquifer material are rare. However, the protection of groundwater resources is an important part in the protection of human health and the assurance of future economic activities. Therefore, expert knowledge regarding the transport, behavior and fate of engineered nanoparticles as potential contaminants in aquifers is essential. The transport and retention behavior of two commercially available engineered AgNPs (one stabilized with a polymere and one with a surfactant) in natural silicate-dominated aquifer material was investigated in saturated laboratory columns. For the experiments a mean grain size diameter of 0.7 mm was chosen with varying silt and clay contents to investigate their effect on the transport behavior of the AgNPs. Typical flow velocities were chosen to represent natural conditions. Particle concentration in the effluent was measured using ICP-MS and the finite element code HYDRUS-1D was used to model the transport and retention processes. The size of the silver nanoparticles in the effluent was analyzed using Flow Field-Flow Fractionation. The obtained results show that silt and clay contents as well as the stabilization of the AgNPs control the transport and retention of AgNPs. Increasing breakthrough was observed with decreasing clay and silt content.

  8. Microscopy based studies on the interaction of bio-based silver nanoparticles with Bombyx mori Nuclear Polyhedrosis virus.

    PubMed

    Tamilselvan, Selvaraj; Ashokkumar, Thirunavukkarasu; Govindaraju, Kasivelu

    2017-04-01

    In the present investigation, silver nanoparticles (AgNPs) interactions with Bombyx mori Nuclear Polyhedrosis virus (BmNPV) were characterized using High-Resolution Scanning Electron Microscopy (HR-SEM), Energy Dispersive X-ray Analysis (EDAX), Transmission Electron Microscopy (TEM), Atomic Force Microcopy (AFM) and Confocal Microscope (CM). HR-SEM study reveals that the biosynthesized AgNPs have interacted with BmNPV and were found on the surface. TEM micrographs of normal and viral polyhedra treated with AgNPs showed that the nanoparticles were accumulated in the membrane and it was noted that some of the AgNPs successfully penetrated the membrane by reaching the capsid of BmNPV. AFM and confocal microscopy studies reveal that the disruption in the shell membrane tends to lose its stability due to exposure of AgNPs to BmNPV. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Cytotoxic effect of silver nanoparticles synthesized from Padina tetrastromatica on breast cancer cell line

    NASA Astrophysics Data System (ADS)

    Gnana Selvi, B. Clara; Madhavan, J.; Santhanam, Amutha

    2016-09-01

    In recent years researchers were attracted towards marine sources due to the presence of active components in it. Seaweeds were widely used in pharmaceutical research for their known biological activities. The biological synthesis method of silver nanoparticles (AgNPs) using Padina tetrastromatica seaweed extract and their cytotoxicity against breast cancer MCF-7 cells was reported in this study. The synthesized AgNPs using seaweed extract were subjected to x-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscope, energy dispersive x-ray, zeta potential to elucidate the structural, morphology, size as well as surface potential parameters. An absorption peak at 430 nm in UV-visible spectrum reveals the excitation and surface plasmon resonance of AgNPs. FE-SEM micrographs exhibits the biosynthesized AgNPs, which are pre-dominantly round shaped and the size ranges between 40-50 nm. The zeta potential value of -27.6 mV confirms the stable nature of biosynthesized silver nanoparticles. Furthermore, the biological synthesized Ag NPs exhibited a dose-dependent cytotoxicity against human breast cancer cell (MCF-7) and the inhibitory concentration (IC50) was found for AgNPs against MCF-7 at 24 h incubation. Biological method of synthesizing silver nanoparticles shows a environmental friendly property which helps in effective electrifying usage in many fields.

  10. A rapid approach for measuring silver nanoparticle concentration and dissolution in seawater by UV-Vis.

    PubMed

    Sikder, Mithun; Lead, Jamie R; Chandler, G Thomas; Baalousha, Mohammed

    2018-03-15

    Detection and quantification of engineered nanoparticles (NPs) in environmental systems is challenging and requires sophisticated analytical equipment. Furthermore, dissolution is an important environmental transformation process for silver nanoparticles (AgNPs) which affects the size, speciation and concentration of AgNPs in natural water systems. Herein, we present a simple approach for the detection, quantification and measurement of dissolution of PVP-coated AgNPs (PVP-AgNPs) based on monitoring their optical properties (extinction spectra) using UV-vis spectroscopy. The dependence of PVP-AgNPs extinction coefficient (ɛ) and maximum absorbance wavelength (λ max ) on NP size was experimentally determined. The concentration, size, and extinction spectra of PVP-AgNPs were characterized during dissolution in 30ppt synthetic seawater. AgNPs concentration was determined as the difference between the total and dissolved Ag concentrations measured by inductively coupled plasma-mass spectroscopy (ICP-MS); extinction spectra of PVP-AgNPs were monitored by UV-vis; and size evolution was monitored by atomic force microscopy (AFM) over a period of 96h. Empirical equations for the dependence of maximum absorbance wavelength (λ max ) and extinction coefficient (ɛ) on NP size were derived. These empirical formulas were then used to calculate the size and concentration of PVP-AgNPs, and dissolved Ag concentration released from PVP-AgNPs in synthetic seawater at variable particle concentrations (i.e. 25-1500μgL -1 ) and in natural seawater at particle concentration of 100μgL -1 . These results suggest that UV-vis can be used as an easy and quick approach for detection and quantification (size and concentration) of sterically stabilized PVP-AgNPs from their extinction spectra. This approach can also be used to monitor the release of Ag from PVP-AgNPs and the concurrent NP size change. Finally, in seawater, AgNPs dissolve faster and to a higher extent with the decrease in NP

  11. Green synthesis and evaluation of silver nanoparticles as adjuvant in rabies veterinary vaccine.

    PubMed

    Asgary, Vahid; Shoari, Alireza; Baghbani-Arani, Fahimeh; Sadat Shandiz, Seyed Ataollah; Khosravy, Mohammad Sadeq; Janani, Alireza; Bigdeli, Razieh; Bashar, Rouzbeh; Cohan, Reza Ahangari

    2016-01-01

    Green synthesis of nanoparticles by plant extracts plays a significant role in different applications. Recently, several studies were conducted on the use of nanoparticles as adjuvant. The main aim of this study was to evaluate green synthesized silver nanoparticles (AgNPs) as adjuvant in rabies veterinary vaccine and compare the results with the existing commercially available alum adjuvant. In the current study, AgNPs were prepared by the reduction of aqueous silver nitrate by leaf extract of Eucalyptus procera. The formation of AgNPs was confirmed by ultraviolet (UV)-visible spectrophotometer, scanning electron microscopy, dynamic light scattering, and X-ray diffraction analysis. Then, different amounts of AgNPs (200 µg, 400 µg, 600 µg, and 800 µg) were added to 1 mL of inactivated rabies virus. The loaded vaccines (0.5 mL) were injected intraperitoneally into six Naval Medical Research Institute mice in each group on days 1 and 7. On the 15th day, the mice were intracerebrally challenged with 0.03 mL of challenge rabies virus (challenge virus strain-11, 20 lethal dose [20 LD50]), and after the latency period of rabies disease in mice (5 days), the mice were monitored for 21 days. Neutralizing antibodies against rabies virus were also investigated using the rapid fluorescent focus inhibition test method. The National Institutes of Health test was performed to determine the potency of optimum concentration of AgNPs as adjuvant. In vitro toxicity of AgNPs was assessed in L929 cell line using MTT assay. In addition, in vivo toxicity of AgNPs and AgNPs-loaded vaccine was investigated according to the European Pharmacopeia 8.0. AgNPs were successfully synthesized, and the identity was confirmed by UV-visible spectrophotometry and X-ray diffraction analysis. The prepared AgNPs were spherical in shape, with an average size of 60 nm and a negative zeta potential of -14 mV as determined by dynamic light scattering technique. The highest percentage of viability was

  12. Silver Nanoparticles: Technological Advances, Societal Impacts, and Metrological Challenges

    PubMed Central

    Calderón-Jiménez, Bryan; Johnson, Monique E.; Montoro Bustos, Antonio R.; Murphy, Karen E.; Winchester, Michael R.; Vega Baudrit, José R.

    2017-01-01

    Silver nanoparticles (AgNPs) show different physical and chemical properties compared to their macroscale analogs. This is primarily due to their small size and, consequently, the exceptional surface area of these materials. Presently, advances in the synthesis, stabilization, and production of AgNPs have fostered a new generation of commercial products and intensified scientific investigation within the nanotechnology field. The use of AgNPs in commercial products is increasing and impacts on the environment and human health are largely unknown. This article discusses advances in AgNP production and presents an overview of the commercial, societal, and environmental impacts of this emerging nanoparticle (NP), and nanomaterials in general. Finally, we examine the challenges associated with AgNP characterization, discuss the importance of the development of NP reference materials (RMs) and explore their role as a metrological mechanism to improve the quality and comparability of NP measurements. PMID:28271059

  13. Silver nanoparticles: technological advances, societal impacts, and metrological challenges

    NASA Astrophysics Data System (ADS)

    Calderón-Jiménez, Bryan; Johnson, Monique E.; Montoro Bustos, Antonio R.; Murphy, Karen E.; Winchester, Michael R.; Vega Baudrit, José R.

    2017-02-01

    Silver nanoparticles (AgNPs) show different physical and chemical properties compared to their macroscale analogs. This is primarily due to their small size and, consequently, the exceptional surface area of these materials. Presently, advances in the synthesis, stabilization, and production of AgNPs have fostered a new generation of commercial products and intensified scientific investigation within the nanotechnology field. The use of AgNPs in commercial products is increasing and impacts on the environment and human health are largely unknown. This article discusses advances in AgNP production and presents an overview of the commercial, societal, and environmental impacts of this emerging nanoparticle (NP), and nanomaterials in general. Finally, we examine the challenges associated with AgNP characterization, discuss the importance of the development of NP reference materials (RMs) and explore their role as a metrological mechanism to improve the quality and comparability of NP measurements.

  14. Silver Nanoparticles: Technological Advances, Societal Impacts, and Metrological Challenges.

    PubMed

    Calderón-Jiménez, Bryan; Johnson, Monique E; Montoro Bustos, Antonio R; Murphy, Karen E; Winchester, Michael R; Vega Baudrit, José R

    2017-01-01

    Silver nanoparticles (AgNPs) show different physical and chemical properties compared to their macroscale analogs. This is primarily due to their small size and, consequently, the exceptional surface area of these materials. Presently, advances in the synthesis, stabilization, and production of AgNPs have fostered a new generation of commercial products and intensified scientific investigation within the nanotechnology field. The use of AgNPs in commercial products is increasing and impacts on the environment and human health are largely unknown. This article discusses advances in AgNP production and presents an overview of the commercial, societal, and environmental impacts of this emerging nanoparticle (NP), and nanomaterials in general. Finally, we examine the challenges associated with AgNP characterization, discuss the importance of the development of NP reference materials (RMs) and explore their role as a metrological mechanism to improve the quality and comparability of NP measurements.

  15. Green synthesis and characterization of silver nanoparticles using Artemisia absinthium aqueous extract--A comprehensive study.

    PubMed

    Ali, Mohammad; Kim, Bosung; Belfield, Kevin D; Norman, David; Brennan, Mary; Ali, Gul Shad

    2016-01-01

    Unlike chemical synthesis, biological synthesis of nanoparticles is gaining tremendous interest, and plant extracts are preferred over other biological sources due to their ample availability and wide array of reducing metabolites. In this project, we investigated the reducing potential of aqueous extract of Artemisia absinthium L. for synthesizing silver nanoparticles (AgNPs). Optimal synthesis of AgNPs with desirable physical and biological properties was investigated using ultra violet-visible spectroscopy (UV-vis), dynamic light scattering (DLS), transmission electron microscopy (TEM) and energy-dispersive X-ray analysis (EDX). To determine their appropriate concentrations for AgNP synthesis, two-fold dilutions of silver nitrate (20 to 0.62 mM) and aqueous plant extract (100 to 0.79 mg ml(-1)) were reacted. The results showed that silver nitrate (2mM) and plant extract (10 mg ml(-1)) mixed in different ratios significantly affected size, stability and yield of AgNPs. Extract to AgNO3 ratio of 6:4v/v resulted in the highest conversion efficiency of AgNO3 to AgNPs, with the particles in average size range of less than 100 nm. Furthermore, the direct imaging of synthesized AgNPs by TEM revealed polydispersed particles in the size range of 5 to 20 nm. Similarly, nanoparticles with the characteristic peak of silver were observed with EDX. This study presents a comprehensive investigation of the differential behavior of plant extract and AgNO3 to synthesize biologically stable AgNPs. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Platycodon saponins from Platycodi Radix ( Platycodon grandiflorum) for the Green Synthesis of Gold and Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Choi, Yoonho; Kang, Sehyeon; Cha, Song-Hyun; Kim, Hyun-Seok; Song, Kwangho; Lee, You Jeong; Kim, Kyeongsoon; Kim, Yeong Shik; Cho, Seonho; Park, Youmie

    2018-01-01

    A green synthesis of gold and silver nanoparticles is described in the present report using platycodon saponins from Platycodi Radix ( Platycodon grandiflorum) as reducing agents. Platycodin D (PD), a major triterpenoidal platycodon saponin, was enriched by an enzymatic transformation of an aqueous extract of Platycodi Radix. This PD-enriched fraction was utilized for processing reduction reactions of gold and silver salts to synthesize gold nanoparticles (PD-AuNPs) and silver nanoparticles (PD-AgNPs), respectively. No other chemicals were introduced during the reduction reactions, providing an entirely green, eco-friendly, and sustainable method. UV-visible spectra showed the surface plasmon resonance bands of PD-AuNPs at 536 nm and PD-AgNPs at 427 nm. Spherically shaped nanoparticles were observed from high-resolution transmission electron microscopy with average diameters of 14.94 ± 2.14 nm for PD-AuNPs and 18.40 ± 3.20 nm for PD-AgNPs. Minor triangular and other polygonal shapes were also observed for PD-AuNPs along with spherical ones. Atomic force microscopy (AFM) images also demonstrated that both nanoparticles were mostly spherical in shape. Curvature-dependent evolution was employed to enhance the AFM images and precisely measure the sizes of the nanoparticles. The sizes were measured as 19.14 nm for PD-AuNPs and 29.93 nm for PD-AgNPs from the enhanced AFM images. Face-centered cubic structures for both nanoparticles were confirmed by strong diffraction patterns from high-resolution X-ray diffraction analyses. Fourier transform infrared spectra revealed the contribution of -OH, aromatic C=C, C-O, and C-H functional groups to the synthesis. Furthermore, the catalytic activity of PD-AuNPs was assessed with a reduction reaction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. The catalytic activity results suggest the potential application of these gold nanoparticles as catalysts in the future. The green strategy reported in this

  17. Exploration of Phyllanthus acidus mediated silver nanoparticles and its activity against infectious bacterial pathogen.

    PubMed

    Sowmya, Cherukuri; Lavakumar, Vuppalapati; Venkateshan, Narayanan; Ravichandiran, Velayutham; Saigopal, D V R

    2018-04-20

    In our present investigation, synthesis of nontoxic, eco friendly and cost effective silver nanoparticles, Phyllanthus acidus (P. acidus) was used as starting material. The influence of phyto-constituents present in aqueous extracts of Phyllanthus acidus was found to be effective in reduction of silver nitrate to free silver nanoparticles (PA-AgNPs). HPTLC finger print analysis reveals the presence of flavonoid, quercetin in aqueous extracts of Phyllanthus acidus. Surface plasmon racemonance exhibited λ max at 462 nm through UV-Vis spectroscopy. Zeta size revealed that the size of nanoparticles were with in the range of 65-250 nm with polydisperse index (PDI) of 0.451. The negative charge of zeta potential value (- 16.4) indicates repulsion among PA-AgNPs with their excellent stability. FESEM-EDAX, XRD and TEM analysis confirmed the presence of nano-crystalline PA-AgNPs with different morphological textures. Further, PA-AgNPs has shown potent antibacterial effect on E. coli cells. The greater antibacterial effect (viable and dead cells) of PA-AgNPs were confirmed by using acridine orange (AO) dye which can able to provide insight of healthy as well as damaged DNA. Live cells emit florescence green and dead cells (treated with PA-AgNPS at 20 and 40 µg/ml) appear as pale orange red colour. Post treatment, investigations of PA-AgNPs on E. coli cells under SEM was found to be effective against cell membrane damages which leads to cell death or cell growth arrest. Hence, from the above findings, we strongly recommend silver nanoparticles from Phyllanthus acidus can be used as a potential source for antimicrobial agent for chronic infections and also against other harmful microorganisms.

  18. Flexible Textile-Based Organic Transistors Using Graphene/Ag Nanoparticle Electrode

    PubMed Central

    Kim, Youn; Kwon, Yeon Ju; Lee, Kang Eun; Oh, Youngseok; Um, Moon-Kwang; Seong, Dong Gi; Lee, Jea Uk

    2016-01-01

    Highly flexible and electrically-conductive multifunctional textiles are desirable for use in wearable electronic applications. In this study, we fabricated multifunctional textile composites by vacuum filtration and wet-transfer of graphene oxide films on a flexible polyethylene terephthalate (PET) textile in association with embedding Ag nanoparticles (AgNPs) to improve the electrical conductivity. A flexible organic transistor can be developed by direct transfer of a dielectric/semiconducting double layer on the graphene/AgNP textile composite, where the textile composite was used as both flexible substrate and conductive gate electrode. The thermal treatment of a textile-based transistor enhanced the electrical performance (mobility = 7.2 cm2·V−1·s−1, on/off current ratio = 4 × 105, and threshold voltage = −1.1 V) due to the improvement of interfacial properties between the conductive textile electrode and the ion-gel dielectric layer. Furthermore, the textile transistors exhibited highly stable device performance under extended bending conditions (with a bending radius down to 3 mm and repeated tests over 1000 cycles). We believe that our simple methods for the fabrication of graphene/AgNP textile composite for use in textile-type transistors can potentially be applied to the development of flexible large-area electronic clothes. PMID:28335276

  19. Phytofabrication of silver nanoparticles using aqueous leaf extract of Xanthium strumerium L. and their bactericidal efficacy

    NASA Astrophysics Data System (ADS)

    Mittal, Jitendra; Jain, Rohit; Mohan Sharma, Madan

    2017-06-01

    An efficient protocol for synthesis of silver nanoparticles (AgNPs) using Xanthium strumerium L. leaves was developed. This study revealed that bioactive compounds present in the extract, function as stabilizing and capping agent for AgNPs. SEM, EDX, TEM and XRD studies confirm the structure, crystalline nature and surface morphology of the AgNPs. Size of synthesized AgNPs was in the range of 20-50 nm having spherical morphology. The AgNPs were found to be toxic against pathogenic bacteria such as Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The use of AgNPs as antibacterial agent is advantageous over other methods for control of pathogenic microorganisms.

  20. Size-dependent surface-enhanced Raman scattering of sodium benzoate on Silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Badr, Y.; Mahmoud, M. A.

    2005-07-01

    The absorption spectrum of silver nanoparticles (Ag NPs) with different size and the transmission electron microscopy (TEM) was recorded. Surface-enhanced Raman scattering (SERS) spectra of Sodium Benzoate (SB) adsorbed on Ag NPs with different particle size were studied. The carboxylic group bands were enhanced as the particle size decreases due to the chemisorption of SB on the Ag NPs through it in which the carboxyl group was perpendicular to the surface and the benzene ring parallel to the surface; the SB bands were enhanced as the coverage density of Ag NPs increased.

  1. Extracellular biosynthesis of silver nanoparticles using Bacillus sp. GP-23 and evaluation of their antifungal activity towards Fusarium oxysporum

    NASA Astrophysics Data System (ADS)

    Gopinath, V.; Velusamy, P.

    2013-04-01

    In last few decades nanoparticles have attracted and emerged as a field in biomedical research due to their incredible applications. The current research was focused on extracellular synthesis of silver nanoparticles (AgNPs) using cell free culture supernatant of strain GP-23. It was found that the strain GP-23 belonged to Bacillus species by 16S rRNA sequence analysis. Biosynthesis of AgNPs was achieved by addition of culture supernatant with aqueous silver nitrate solution, after 24 h it turned to brown color solution with a peak at 420 nm corresponding to the Plasmon absorbance of AgNPs by UV-Vis Spectroscopy. The nanoparticles were characterized by FTIR, XRD, HRTEM, EDX and AFM. The synthesized nanoparticles were found to be spherical in shape with size in the range of 7-21 nm. It was stable in aqueous solution for five months period of storage at room temperature under dark condition. The biosynthesized AgNPs exhibited strong antifungal activity against plant pathogenic fungus, Fusarium oxysporum at the concentration of 8 μg ml-1. The results suggest that the synthesized AgNPs act as an effective antifungal agent/fungicide.

  2. Transport, retention, and long-term release behavior of polymer-coated silver nanoparticles in saturated quartz sand: The impact of natural organic matters and electrolyte.

    PubMed

    Hou, Jun; Zhang, Mingzhi; Wang, Peifang; Wang, Chao; Miao, Lingzhan; Xu, Yi; You, Guoxiang; Lv, Bowen; Yang, Yangyang; Liu, Zhilin

    2017-10-01

    This study investigated the transport and long-term release of stabilized silver nanoparticles (AgNPs), including polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) and bare AgNPs (Bare-AgNPs), in the presence of natural organic matters (NOMs; both humic acids (HA) and alginate (Alg)) and an electrolyte (Ca 2+ ) in a sand-packed column. Very low breakthrough rate (C/C 0 ) of AgNPs (below 0.04) occurred in the absence of NOM and the electrolyte. Increasing the concentration of NOM and decreasing the influent NOM solution's ionic strength (IS) reduced the retention of AgNPs. The reduced NP retention at high NOM and low IS was mainly attributed to the increased energy barrier between the AgNPs and the sand grain surface. Notably, the retention of PVP-AgNPs was enhanced at high Alg concentration and low IS, which mainly resulted from the improved hydrophobicity that could increase the interaction between the PVP-AgNPs and the collector. The total release amount of PVP-AgNPs (10.03%, 9.50%, 28.42%, 6.37%) and Bare-AgNPs (3.28%, 2.58%, 10.36%, 1.54%) were gained when exposed to four kinds of NOM solutions, including deionized water, an electrolyte solution (1 mM Ca 2+ ), HA with an electrolyte (1 mM Ca 2+ ), and a Alg (40 mg/L) solution with an electrolyte (1 mM Ca 2+ ). The long-term release of retained silver nanoparticles in the quartz sand was mostly through the form of released Ag NPs. The factors that increased the mobility of AgNPs in quartz sand could improve the release of the AgNPs. The release of AgNPs had no significant change in the presence Ca 2+ but were increased in the presence of HA. The Alg slightly decreased the release of AgNPs by increasing the hydrophobicity of AgNPs. The results of the study indicated that all the tested NOM and Ca 2+ have prominent influence on the transport and long-term release behavior of silver nanoparticles in saturated quartz sand. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. In situ characterization of silver nanoparticle synthesis in maltodextrin supramolecular structures

    DOE PAGES

    Bell, Nelson S.; Dunphy, Darren R.; Lambert, Timothy N.; ...

    2015-06-26

    In this study, the use of maltodextrin supramolecular structures (MD SMS) as a reducing agent and colloidal stabilizing agent for the synthesis of Ag nanoparticles (Ag NPs) identified three key points. First, the maltodextrin (MD) solutions are effective in the formation of well-dispersed Ag NPs utilizing alkaline solution conditions, with the resulting Ag NPs ranging in size from 5 to 50 nm diameter. Second, in situ characterization by Raman spectroscopy and small angle X-ray scattering (SAXS) are consistent with initial nucleation of Ag NPs within the MD SMS up to a critical size of ca. 1 nm, followed by amore » transition to more rapid growth by aggregation and fusion between MD SMS, similar to micelle aggregation reactions. Third, the stabilization of larger Ag NPs by adsorbed MD SMS is similar to hemi-micelle stabilization, and monomodal size distributions are proposed to relate to integer surface coverage of the Ag NPs. Conditions were identified for preparing Ag NPs with monomodal distributions centered at 30–35 nm Ag NPs.« less

  4. Green synthesis of silver nanoparticles using Mentha pulegium and investigation of their antibacterial, antifungal and anticancer activity.

    PubMed

    Kelkawi, Ali Hamad Abd; Abbasi Kajani, Abolghasem; Bordbar, Abdol-Khalegh

    2017-06-01

    A simple and eco-friendly method for efficient synthesis of stable colloidal silver nanoparticles (AgNPs) using Mentha pulegium extracts is described. A series of reactions was conducted using different types and concentrations of plant extract as well as metal ions to optimize the reaction conditions. AgNPs were characterized by using UV-vis spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering, zetasizer, energy-dispersive X-ray spectroscopy (EDAX) and Fourier transform infrared spectroscopy (FTIR). At the optimized conditions, plate shaped AgNPs with zeta potential value of -15.7 and plasmon absorption maximum at 450 nm were obtained using high concentration of aqueous extract. Efficient adsorption of organic compounds on the nanoparticles was confirmed by FTIR and EDAX. The biogenic AgNPs displayed promising antibacterial activity on Escherichia coli , Staphylococcus aureus , and Streptococcus pyogenes . The highest antibacterial activity of 25 µg mL-1 was obtained for all the strains using aqueous extract synthesized AgNPs. The aqueous extract synthesised AgNPs also showed considerable antifungal activity against fluconazole resistant Candida albicans . The cytotoxicity assay revealed considerable anticancer activity of AgNPs on HeLa and MCF-7 cancer cells. Overall results indicated high potential of M. pulegium extract to synthesis high quality AgNPs for biomedical applications.

  5. Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging.

    PubMed

    Li, Jiuxing; Zhu, Zhi; Zhu, Bingqing; Ma, Yanli; Lin, Bingqian; Liu, Rudi; Song, Yanling; Lin, Hui; Tu, Song; Yang, Chaoyong

    2016-08-02

    Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging.

  6. Chemically synthesized silver nanoparticles as cell lysis agent for bacterial genomic DNA isolation

    NASA Astrophysics Data System (ADS)

    Goswami, Gunajit; Boruah, Himangshu; Gautom, Trishnamoni; Jyoti Hazarika, Dibya; Barooah, Madhumita; Boro, Robin Chandra

    2017-12-01

    Silver nanoparticles (AgNPs) have seen a recent spurt of use in varied fields of science. In this paper, we showed a novel application of AgNP as a promising microbial cell-lysis agent for genomic DNA isolation. We utilized chemically synthesized AgNPs for lysing bacterial cells to isolate their genomic DNA. The AgNPs efficiently lysed bacterial cells to yield good quality DNA that could be subsequently used for several molecular biology works.

  7. Optimization and antioxidant properties of phytosynthesized silver nanoparticles using Dianthus caryophyllus L. (carnation)

    NASA Astrophysics Data System (ADS)

    Rachna, Saharan, Baljeet Singh; Yadav, M. S.; Sharma, Nisha

    2016-05-01

    In the recent years, silver nanoparticles have been the focus of Nanobiotechnology due to their unique interdisciplinary applications in the field of biomedicals, material diagnostics, optics and chemistry. A wide set of physical and chemical methods have been devised for providing the effective and efficient synthesis procedure of silver nanoparticles (AgNPs) but are somehow expensive and involve toxic substances. There is a critical need to develop reliable and eco-friendly process for synthesizing silver nanoparticles. In the present investigation, a simple and cost-effective green approach has been utilized for the production of stable silver nanoparticles by employing Dianthus caryophyllus flower extract. Different optimization conditions were checked for extract capped AgNPs and characterized by UV-Visible spectrophotometer. The optimum 0.02 dilution of extract found efficient to reduce 4 mM silver ions in the ratio 60:40 at pH 9. The antioxidant potential of the resultant AgNPs was observed using Hydrogen peroxide assay. There was an increasing trend of antioxidant property with increasing concentration. This potential of these photosynthesized AgNPs makes them reliable for good cause of society, mainly in therapeutic and biomedical applications.

  8. Plasmon assisted enhanced nonlinear refraction of monodispersed silver nanoparticles and their tunability.

    PubMed

    Lama, Pemba; Suslov, Anatoliy; Walser, Ardie D; Dorsinville, Roger

    2014-06-02

    Nonlinear optical characterizations were performed on monodispersed silver (Ag) nanoparticles (NPs) of various sizes using a picosecond Z-scan technique with excitation wavelengths of 532 nm and 1064 nm. The Ag NPs were fabricated using a heterogeneous condensation technique in a gas medium. The nonlinear refraction values were higher for the monodispersed Ag NPs whose surface plasmon resonance (SPR) peak is closer to the excitation wavelength. The higher nonlinear optical response is explained in terms of an electric field enhancement near the SPR. Moreover, the fabrication method allows the tailoring of the nonlinear refraction index of the Ag NPs by tuning the SPR peak of the sample. A comparison of the nonlinear refraction index of the monodispersed and polydispersed Ag NPs showed that the nonlinear refractive index of the monodispersed Ag NPs is higher.

  9. Robust one pot synthesis of colloidal silver nanoparticles by simple redox method and absorbance recovered sensing.

    PubMed

    Salman, Muhammad; Iqbal, Mahwish; El Ashry, El Sayed H; Kanwal, Shamsa

    2012-01-01

    Conventional synthesis of silver nanoparticles employs a reducing agent and a capping agent. In this report water-soluble silver nanoparticles (AgNPs) were prepared facilely by chemical reduction of Ag(I) ions. 4-Amino-3-(d-gluco-pentitol-1-yl)-4,5-dihydro-1,2,4-triazole-5-thione (AGTT) was used both as reducing and stabilizing agent. Direct heating methodology was found to be more suitable for achieving particles with a hydrodynamic diameter of ~20 nm. AGTT exists as tautomer in solution form and our studies indicate that -NH(2) group is involved in the reduction and stabilization of Ag(+) and thione (Δ=S) group of AGTT is possibly involved in stabilizing the nanoparticles via coordinate covalent linkage. Characterization of synthesized silver nanoparticles was performed by UV-vis, FT-IR and by FESEM. Based on the absorption properties of synthesized AgNPs, we used AgNPs to detect bovine serum albumin (BSA) and AgNPs-BSA composite nanoprobe was further applied to detect Cu(2+) based on absorbance recovery. The proposed method has advantages over existing methods in terms of rapid synthesis and stability of AgNPs and their applications. Analysis is reproducible, cost effective and highly sensitive. The lowest detectable concentration of BSA in this approach is 3 nM, and for Cu(2+) it can detect upto 200 pM. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Exploring the interaction of silver nanoparticles with pepsin and its adsorption isotherms and kinetics.

    PubMed

    Li, Xiangrong; Wang, Kaiwei; Peng, Yanru

    2018-04-25

    The interaction of nanoparticles (NPs) with proteins is a topic of high relevance for the medical application of nanomaterials. In the study, a comprehensive investigation was performed for the binding properties of silver nanoparticles (AgNPs) to pepsin. The results indicate that the binding of AgNPs to pepsin may be a static quenching mechanism. Thermodynamic analysis reveals that AgNPs binds to pepsin is synergistically driven by enthalpy and entropy, and the major driving forces are hydrophobic and electrostatic interactions. Synchronous fluorescence spectroscopy shows that AgNPs may induce microenvironmental changes of pepsin. The hydrophobicity of Trp is increased while the hydrophility of Tyr is increased. The adsorption of pepsin on AgNPs was analyzed by Langmuir and Freundlich models, suggesting that the equilibrium adsorption data fit well with Freundlich model. The equilibrium adsorption data were modeled using the pseudo-first-order and pseudo-second-order kinetic equations. The results indicate that pseudo-second-order kinetic equation better describes the adsorption kinetics. The study provides an accurate and full basic data for clarifying the binding mechanism, adsorption isotherms and kinetic behaviors of AgNPs with pepsin. These fundamental works will provide some new insights into the safe and effective application of AgNPs in biological and medical areas. Copyright © 2018 Elsevier B.V. All rights reserved.

  11. Unnatural amino acid-mediated synthesis of silver nanoparticles and their antifungal activity against Candida species

    NASA Astrophysics Data System (ADS)

    Narayanan, Kannan Badri; Park, Hyun Ho

    2014-08-01

    In this study, the biocompatible unnatural amino acid, 3,4-dihydroxy- l-phenylalanine ( l-dopa), which is used in protein engineering, was employed in the facile synthesis of silver nanoparticles (AgNPs). The surface plasmon resonance (SPR) band of the UV-Vis spectrum at 406 nm demonstrates the possibility of formation of smaller nanoparticles; the symmetrical shape of the band demonstrates a narrow size distribution of AgNPs, the formation of AgNPs, and the face-centered cubic (fcc) crystalline structure of nanoparticles was confirmed by X-ray diffraction (XRD). Additionally, transmission electron microscopic (TEM) images revealed that these particles were spherical in shape with diameters of 2.7-12.2 nm (average = 8.7 nm). These nanoparticles exhibited antifungal activity against both planktonic and biofilm yeast cells of Candida albicans and C. dubliniensis. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were determined by microdilution assays. C. albicans were shown to be less susceptible than C. dubliniensis to AgNPs based on the MIC (ranging from 7.8 to 15.6 µg ml-1) and MFC (ranging from 31.2 to 62.5 µg ml-1). With regard to biomass quantification, AgNPs did not induce a significant reduction of the biomass of Candida species; however, treatment of biofilm with 500 µg/ml of AgNPs induced a 2.99-log10 ( P < 0.001) and 3.53-log10 ( P < 0.001) significant reduction in the number of culturable cells of CFUs when compared to control samples of C. albicans and C. dubliniensis, respectively. Thus, AgNPs-based antifungal agents would be an effective alternative to conventional drugs to overcome drug resistance in Candida-associated infections.

  12. Preparation of silver nanoparticles loaded graphene oxide nanosheets for antibacterial activity

    NASA Astrophysics Data System (ADS)

    T, T. T., Vi; Lue, S. J.

    2016-11-01

    A simple, facile method to fabricate successfully silver nanoparticle (AgNPs) decorated on graphene oxide (GO) layers via grafted thiol groups. Samples were prepared with different concentrations of AgNO3. Resulting AgNPs were quasi-spherical in shape and attached on the layers of GO. Physical properties were confirmed by X-ray diffraction (XRD), zeta potential, dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectra, thermogravimetric analyzer (TGA), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). Antimicrobial test was effectively showed using MRSA (Staphylococcus areus). The GO-Ag NPs with appropriate Ag NPs content of 0.2 M AgNO3 exhibited the strongest antibacterial activity at 48.77% inhibition after 4 hours incubation.

  13. Biogenic synthesis of silver nanoparticles and their antioxidant and antibacterial activity

    NASA Astrophysics Data System (ADS)

    Bhakya, S.; Muthukrishnan, S.; Sukumaran, M.; Muthukumar, M.

    2016-06-01

    Nanomedicine utilizes biocompatible nanomaterials for diagnostic and therapeutic purposes. The present study reports the use of Helicteres isora root extract for the synthesis of silver nanoparticles (AgNPs). The synthesized AgNPs were initially noticed through visual color change from yellow to reddish brown and further confirmed by surface plasmonic resonance (SPR) band at 450 nm using UV-visible spectroscopy. Morphology and size of AgNPs were determined by transmission electron microscopy (TEM) analysis. X-ray diffraction (XRD) study revealed crystalline nature of AgNPs. The prolonged stability of AgNPs was due to capping of oxidized polyphenols and carboxyl protein which was established by Fourier transform infrared spectroscopy (FTIR) study. In addition, the synthesized AgNPs were tested for antioxidant and antibacterial activities. It showed good antioxidant activity as compared to butylated hydroxytoluene (BHT) and ascorbic acid as standard antioxidant. It could be concluded that H. isora root extract can be used efficiently in the production of potential antioxidant and antibacterial AgNPs for commercial application.

  14. Characterization of phytoconstituents and evaluation of antimicrobial activity of silver-extract nanoparticles synthesized from Momordica charantia fruit extract.

    PubMed

    Rashid, Md Mamun Or; Akhter, Kazi Nahid; Chowdhury, Jakir Ahmed; Hossen, Foysal; Hussain, Md Saddam; Hossain, Md Tanvir

    2017-06-26

    Our present study was conducted to characterize the phytoconstituents present in the aqueous extract of Momordica charantia and evaluate the antimicrobial efficacy of silver-extract nanoparticles (Ag-Extract-NPs). Silver nanoparticles (AgNPs) were prepared by reducing AgNO 3; and NaBH 4 served as reducing agent. After screening of phytochemicals; AgNPs and aqueous extract were mixed thoroughly and then coated by polyaniline. These NPs were characterized by using Visual inspection, UV spectroscopy, FTIR, SEM and TEM techniques. Antimicrobial activities were assessed against Staphylococcus aureus, Salmonella typhi, Escherichia coli and Pseudomonas aeruginosa. Aqueous extract of M. charantia fruits contain alkaloid, phenol, saponin etc. UV-Vis spectrum showed strong absorption peak around 408 nm. The presence of -CH, -NH, -COOH etc. stretching in FTIR spectrum of Ag-Extract-NPs endorsed that AgNPs were successfully capped by bio-compounds. SEM and TEM result revealed that synthesized NPs had particle size 78.5-220 nm. Ag-Extract-NPs showed 34.6 ± 0.8 mm zone of inhibition against E. coli compared to 25.6 ± 0.5 mm for ciprofloxacin. Maximum zone of inhibition for Ag-Extract-NPs were 24.8 ± 0.7 mm, 26.4 ± 0.4 mm, 7.4 ± 0.4 mm for S. aureus, P. aeruginosa and S. typhi. We found that Ag-Extract-NPs have much better antibacterial efficacy than AgNPs and M. charantia extract has individually. It is also noticed that gram negative bacteria (except S. typhi) are more susceptible to Ag-Extract-NPs than gram positive bacteria. Ag-Extract-NPs showed strong antibacterial activity. In order to make a reliable stand for mankind, further study is needed to consider determining the actual biochemical pathway by which AgNPs-extracts exert their antimicrobial effect.

  15. Does water chemistry affect the dietary uptake and toxicity of silver nanoparticles by the freshwater snail Lymnaea stagnalis?

    USGS Publications Warehouse

    López-Serrano Oliver, Ana; Croteau, Marie-Noële; Stoiber, Tasha L.; Tejamaya, Mila; Römer, Isabella; Lead, Jamie R.; Luoma, Samuel N.

    2014-01-01

    Silver nanoparticles (AgNPs) are widely used in many applications and likely released into the aquatic environment. There is increasing evidence that Ag is efficiently delivered to aquatic organisms from AgNPs after aqueous and dietary exposures. Accumulation of AgNPs through the diet can damage digestion and adversely affect growth. It is well recognized that aspects of water quality, such as hardness, affect the bioavailability and toxicity of waterborne Ag. However, the influence of water chemistry on the bioavailability and toxicity of dietborne AgNPs to aquatic invertebrates is largely unknown. Here we characterize for the first time the effects of water hardness and humic acids on the bioaccumulation and toxicity of AgNPs coated with polyvinyl pyrrolidone (PVP) to the freshwater snail Lymnaea stagnalis after dietary exposures. Our results indicate that bioaccumulation and toxicity of Ag from PVP-AgNPs ingested with food are not affected by water hardness and by humic acids, although both could affect interactions with the biological membrane and trigger nanoparticle transformations. Snails efficiently assimilated Ag from the PVP-AgNPs mixed with diatoms (Ag assimilation efficiencies ranged from 82 to 93%). Rate constants of Ag uptake from food were similar across the entire range of water hardness and humic acid concentrations. These results suggest that correcting regulations for water quality could be irrelevant and ineffective where dietary exposure is important.

  16. Biological activity of green-synthesized silver nanoparticles depends on the applied natural extracts: a comprehensive study.

    PubMed

    Rónavári, Andrea; Kovács, Dávid; Igaz, Nóra; Vágvölgyi, Csaba; Boros, Imre Miklós; Kónya, Zoltán; Pfeiffer, Ilona; Kiricsi, Mónika

    2017-01-01

    Due to obvious disadvantages of the classical chemical methods, green synthesis of metallic nanoparticles has attracted tremendous attention in recent years. Numerous environmentally benign synthesis methods have been developed yielding nanoparticles via low-cost, eco-friendly, and simple approaches. In this study, our aim was to determine the suitability of coffee and green tea extracts in green synthesis of silver nanoparticles as well as to compare the performance of the obtained materials in different biological systems. We successfully produced silver nanoparticles (C-AgNP and GT-AgNP) using coffee and green tea extracts; moreover, based on our comprehensive screening, we delineated major differences in the biological activity of C-AgNPs and GT-AgNPs. Our results indicate that although GT-AgNPs exhibited excellent antimicrobial activity against all the examined microbial pathogens, these particles were also highly toxic to mammalian cells, which limits their potential applications. On the contrary, C-AgNPs manifested substantial inhibitory action on the tested microbes but were nontoxic to human and mouse cells, indicating an outstanding capacity to discriminate between potential pathogens and mammalian cells. These results clearly show that the various green materials used for stabilization and for reduction of metal ions have a defining role in determining and fine-tuning the biological activity of the obtained nanoparticles.

  17. Biological activity of green-synthesized silver nanoparticles depends on the applied natural extracts: a comprehensive study

    PubMed Central

    Rónavári, Andrea; Kovács, Dávid; Igaz, Nóra; Vágvölgyi, Csaba; Boros, Imre Miklós; Kónya, Zoltán; Pfeiffer, Ilona; Kiricsi, Mónika

    2017-01-01

    Due to obvious disadvantages of the classical chemical methods, green synthesis of metallic nanoparticles has attracted tremendous attention in recent years. Numerous environmentally benign synthesis methods have been developed yielding nanoparticles via low-cost, eco-friendly, and simple approaches. In this study, our aim was to determine the suitability of coffee and green tea extracts in green synthesis of silver nanoparticles as well as to compare the performance of the obtained materials in different biological systems. We successfully produced silver nanoparticles (C-AgNP and GT-AgNP) using coffee and green tea extracts; moreover, based on our comprehensive screening, we delineated major differences in the biological activity of C-AgNPs and GT-AgNPs. Our results indicate that although GT-AgNPs exhibited excellent antimicrobial activity against all the examined microbial pathogens, these particles were also highly toxic to mammalian cells, which limits their potential applications. On the contrary, C-AgNPs manifested substantial inhibitory action on the tested microbes but were nontoxic to human and mouse cells, indicating an outstanding capacity to discriminate between potential pathogens and mammalian cells. These results clearly show that the various green materials used for stabilization and for reduction of metal ions have a defining role in determining and fine-tuning the biological activity of the obtained nanoparticles. PMID:28184158

  18. Precise localization of metal nanoparticles in dendrimer nanosnakes or inner periphery and consequences in catalysis

    NASA Astrophysics Data System (ADS)

    Liu, Xiang; Gregurec, Danijela; Irigoyen, Joseba; Martinez, Angel; Moya, Sergio; Ciganda, Roberto; Hermange, Philippe; Ruiz, Jaime; Astruc, Didier

    2016-10-01

    Understanding the relationship between the location of nanoparticles (NPs) in an organic matrix and their catalytic performances is essential for catalyst design. Here we show that catalytic activities of Au, Ag and CuNPs stabilized by dendrimers using coordination to intradendritic triazoles, galvanic replacement or stabilization outside dendrimers strongly depends on their location. AgNPs are found at the inner click dendrimer periphery, whereas CuNPs and AuNPs are encapsulated in click dendrimer nanosnakes. AuNPs and AgNPs formed by galvanic replacement are larger than precursors and only partly encapsulated. AuNPs are all the better 4-nitrophenol reduction catalysts as they are less sterically inhibited by the dendrimer interior, whereas on the contrary CuNPs are all the better alkyne azide cycloaddition catalysts as they are better protected from aerobic oxidation inside dendrimers. This work highlights the role of the location in macromolecules on the catalytic efficiency of metal nanoparticles and rationalizes optimization in catalyst engineering.

  19. Dendrimer encapsulated Silver nanoparticles as novel catalysts for reduction of aromatic nitro compounds

    NASA Astrophysics Data System (ADS)

    Asharani, I. V.; Thirumalai, D.; Sivakumar, A.

    2017-11-01

    Polyethylene glycol (PEG) core dendrimer encapsulated silver nanoparticles (AgNPs) were synthesized through normal chemical reduction method, where dendrimer acts as reducing and stabilizing agent. The encapsulated AgNPs were well characterized using TEM, DLS and XPS techniques. The synthesized AgNPs showed excellent catalytic activity towards the reduction of aromatic nitro compounds with sodium borohydride as reducing agent and the results substantiate that dendrimer encapsulated AgNPs can be an effective catalyst for the substituted nitro aromatic reduction reactions. Also the kinetics of different nitro compounds reductions was studied and presented.

  20. Voltammetric studies of Azathioprine on the surface of graphite electrode modified with graphene nanosheets decorated with Ag nanoparticles.

    PubMed

    Asadian, Elham; Iraji Zad, Azam; Shahrokhian, Saeed

    2016-01-01

    By using graphene nanosheets decorated with Ag nanoparticles (AgNPs-G) as an effective approach for the surface modification of pyrolytic graphite electrode (PGE), a sensing platform was fabricated for the sensitive voltammetric determination of Azathioprine (Aza). The prepared AgNPs-G nanosheets were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis and Raman spectroscopy techniques. The electrochemical behavior of Aza was investigated by means of cyclic voltammetry. Comparing to the bare PGE, a remarkable enhancement was observed in the response characteristics of Aza on the surface of the modified electrode (AgNPs-G/PGE) as well as a noticeable decrease in its reduction overpotential. These results can be attributed to the incredible enlargement in the microscopic surface area of the electrode due to the presence of graphene nanosheets together with strong adsorption of Aza on its surface. The effect of experimental parameters such as accumulation time, the amount of modifier suspension and pH of the supporting electrolyte were also optimized toward obtaining the maximum sensitivity. Under the optimum conditions, the calibration curve studies demonstrated that the peak current increased linearly with Aza concentrations in the range of 7 × 10(-7) to 1 × 10(-4)mol L(-1) with the detection limit of 68 nM. Further experiments revealed that the modified electrode can be successfully applied for the accurate determination of Aza in pharmaceutical preparations. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Characterization of Silver Nanoparticles Internalized by Arabidopsis Plants Using Single Particle ICP-MS Analysis

    PubMed Central

    Bao, Dongping; Oh, Zhen Guo; Chen, Zhong

    2016-01-01

    Plants act as a crucial interface between humans and their environment. The wide use of nanoparticles (NPs) has raised great concerns about their potential impacts on crop health and food safety, leading to an emerging research theme about the interaction between plants and NPs. However, up to this day even the basic issues concerning the eventual fate and characteristics of NPs after internalization are not clearly delineated due to the lack of a well-established technique for the quantitative analysis of NPs in plant tissues. We endeavored to combine a quantitative approach for NP analysis in plant tissues with TEM to localize the NPs. After using an enzymatic digestion to release the NPs from plant matrices, single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS) is employed to determine the size distribution of silver nanoparticles (Ag NPs) in tissues of the model plant Arabidopsis thaliana after exposure to 10 nm Ag NPs. Our results show that Macerozyme R-10 treatment can release Ag NPs from Arabidopsis plants without changing the size of Ag NPs. The characteristics of Ag NPs obtained by SP-ICP-MS in both roots and shoots are in agreement with our transmission electron micrographs, demonstrating that the combination of an enzymatic digestion procedure with SP-ICP-MS is a powerful technique for quantitative determination of NPs in plant tissues. Our data reveal that Ag NPs tend to accumulate predominantly in the apoplast of root tissues whereby a minor portion is transported to shoot tissues. Furthermore, the fact that the measured size distribution of Ag NPs in plant tissue is centered at around 20.70 nm, which is larger than the initial 12.84 nm NP diameter, strongly implies that many internalized Ag NPs do not exist as intact individual particles anymore but are aggregated and/or biotransformed in the plant instead. PMID:26870057

  2. Short-term soil bioassays may not reveal the full toxicity potential for nanomaterials; bioavailability and toxicity of silver ions (AgNO₃) and silver nanoparticles to earthworm Eisenia fetida in long-term aged soils.

    PubMed

    Diez-Ortiz, Maria; Lahive, Elma; George, Suzanne; Ter Schure, Anneke; Van Gestel, Cornelis A M; Jurkschat, Kerstin; Svendsen, Claus; Spurgeon, David J

    2015-08-01

    This study investigated if standard risk assessment hazard tests are long enough to adequately provide the worst case exposure for nanomaterials. This study therefore determined the comparative effects of the aging on the bioavailability and toxicity to earthworms of soils dosed with silver ions and silver nanoparticles (Ag NP) for 1, 9, 30 & 52 weeks, and related this to the total Ag in the soil, Ag in soil pore water and earthworm tissue Ag concentrations. For ionic Ag, a classical pattern of reduced bioavailability and toxicity with time aged in the soil was observed. For the Ag NP, toxicity increased with time apparently driven by Ag ion dissolution from the added Ag NPs. Internal Ag in the earthworms did not always explain toxicity and suggested the presence of an internalised, low-toxicity Ag fraction (as intact or transformed NPs) after shorter aging times. Our results indicate that short-term exposures, without long-term soil aging, are not able to properly assess the environmental risk of Ag NPs and that ultimately, with aging time, Ag ion and Ag NP effect will merge to a common value. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Extracellular synthesis of silver nanoparticles using the leaf extract of Coleus amboinicus Lour

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Narayanan, Kannan Badri; Sakthivel, Natarajan, E-mail: puns2005@gmail.com

    2011-10-15

    Highlights: {yields} Synthesis of AgNPs using the leaf extract of Coleus amboinicus L. was described. {yields} UV-vis absorption spectra showed the formation of isotrophic AgNPs at 437 nm in 6 h. {yields} XRD analysis showed intense peaks corresponding to fcc structure of AgNPs. {yields} HR-TEM analysis revealed the formation of stable anisotrophic and isotrophic AgNPs. -- Abstract: In the present investigation, Coleus amboinicus Lour. leaf extract-mediated green chemistry approach for the synthesis of silver nanoparticles was described. The nanoparticles were characterized by ultraviolet-visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR) and transmissionmore » electron microscopy (TEM). The influence of leaf extract on the control of size and shape of silver nanoparticles is reported. Upon an increase in the concentration of leaf extract, there was a shift in the shape of nanoparticles from anisotrophic nanostructures like triangle, decahedral and hexagonal to isotrophic spherical nanoparticles. Crystalline nature of fcc structured nanoparticles was confirmed by XRD spectrum with peaks corresponding to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes and bright circular spots in the selected-area electron diffraction (SAED). Such environment friendly and sustainable methods are non-toxic, cheap and alternative to hazardous chemical procedures.« less

  4. Immunomodulatory properties of silver nanoparticles contribute to anticancer strategy for murine fibrosarcoma

    PubMed Central

    Chakraborty, Biswajit; Pal, Ramkrishna; Ali, Mohammed; Singh, Leichombam Mohindro; Shahidur Rahman, Dewan; Kumar Ghosh, Sujit; Sengupta, Mahuya

    2016-01-01

    The use of nanotechnology in nanoparticle-based cancer therapeutics is gaining impetus due to the unique biophysical properties of nanoparticles at the quantum level. Silver nanoparticles (AgNPs) have been reported as one type of potent therapeutic nanoparticles. The present study is aimed to determine the effect of AgNPs in arresting the growth of a murine fibrosarcoma by a reductive mechanism. Initially, a bioavailability study showed that mouse serum albumin (MSA)-coated AgNPs have enhanced uptake; therefore, toxicity studies of AgNP-MSA at 10 different doses (1–10 mg/kg b.w.) were performed in LACA mice by measuring the complete blood count, lipid profile and histological parameters. The complete blood count, lipid profile and histological parameter results showed that the doses from 2 to 8 mg (IC50: 6.15 mg/kg b.w.) sequentially increased the count of leukocytes, lymphocytes and granulocytes, whereas the 9- and 10-mg doses showed conclusive toxicity. In an antitumor study, the incidence and size of fibrosarcoma were reduced or delayed when murine fibrosarcoma groups were treated by AgNP-MSA. Transmission electron micrographs showed that considerable uptake of AgNP-MSA by the sentinel immune cells associated with tumor tissue and a morphologically buckled structure of the immune cells containing AgNP-MSA. Because the toxicity studies revealed a relationship between AgNPs and immune function, the protumorigenic cytokines TNF-α, IL-6 and IL-1β were also assayed in AgNP-MSA-treated and non-treated fibrosarcoma groups, and these cytokines were found to be downregulated after treatment with AgNP-MSA. PMID:25938978

  5. Mechanism of Silver Nanoparticles Action on Insect Pigmentation Reveals Intervention of Copper Homeostasis

    PubMed Central

    Armstrong, Najealicka; Ramamoorthy, Malaisamy; Lyon, Delina; Jones, Kimberly; Duttaroy, Atanu

    2013-01-01

    Silver nanoparticles (AgNPs), like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities past that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, we attempted to monitor the effects of AgNPs at a nonlethal concentration on wild type Drosophila melanogaster by exposing them throughout their development. All adult flies raised in AgNP doped food showed that up to 50 mg/L concentration AgNP has no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised due to AgNP feeding. Determination of the amount of free ionic silver (Ag+) led us to claim that the observed biological effects have resulted from the AgNPs and not from Ag+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, are decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Consequently, we propose a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explains the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, we claim that Drosophila, an established genetic model system, can be well utilized for further understanding of the biological effects of nanoparticles. PMID:23308159

  6. Differently Environment Stable Bio-Silver Nanoparticles: Study on Their Optical Enhancing and Antibacterial Properties

    PubMed Central

    Balachandran, Yekkuni L.; Girija, Shanmugam; Selvakumar, Rajendran; Tongpim, Saowanit; Gutleb, Arno C.; Suriyanarayanan, Sarvajeyakesavalu

    2013-01-01

    Generally, limited research is extended in studying stability and applicational properties of silver nanoparticles (Ag NPs) synthesized by adopting ‘green chemistry’ protocol. In this work, we report on the synthesis of stable Ag NPs using plant-derived materials such as leaf extract of Neem (Azadirachta indica) and biopolymer pectin from apple peel. In addition, the applicational properties of Ag NPs such as surface-enhanced Raman scattering (SERS) and antibacterial efficiencies were also investigated. As-synthesized nanoparticles (NPs) were characterized using various instrumentation techniques. Both the plant materials (leaf extract and biopolymer) favored the synthesis of well-defined NPs capped with biomaterials. The NPs were spherical in shape with an average particle size between 14-27 nm. These bio-NPs exhibited colloidal stability in most of the suspended solutions such as water, electrolyte solutions (NaCl; NaNO3), biological solution (bovine serum albumin), and in different pH solutions (pH 7; 9) for a reasonable time period of 120 hrs. Both the bio-NPs were observed to be SERS active through displaying intrinsic SERS signals of the Raman probe molecule (Nile blue A). The NPs were effective against the Escherichia coli bacterium when tested in nutrient broth and agar medium. Scanning and high-resolution transmission electron microscopy (SEM and HRTEM) images confirmed cellular membrane damage of nanoparticle treated E. coli cells. These environmental friendly template Ag NPs can be used as an antimicrobial agent and also for SERS based analytical applications. PMID:24130832

  7. Green synthesis of Ag nanoparticles using plant metabolites

    NASA Astrophysics Data System (ADS)

    Filippi, Antonio; Mattiello, Alessandro; Musetti, Rita; Petrussa, Elisa; Braidot, Enrico; Marchiol, Luca

    2017-08-01

    Nano-biotechnology is one of the most promising areas in modern nanoscience and technology. In this emerging area of research, nanoparticles (NPs) play an important role since the large-scale production and huge numbers of utilization. Gold and silver nanoparticles are among the most extensively studied nanomaterials, since they show high stability and low chemical reactivity in comparison to other metals. They are commonly synthesized using toxic chemical reducing agents able to reduce metal ions into uncharged NPs and/or high energy supplied procedures. The most commonly used method for the synthesis of NPs requires toxic chemicals like N,N-dimethyl formamide (DMF) or trisodium citrate, but recently a green technique, based on natural reducing agents, has been suggested to substitute the nature-unfriendly chemical methods. Many scientific works put in evidence the efficacy of plant extracts to reduce metal salts into the respective NPs, but this process lacks a clear control of NPs shapes and dimensions, since many different metabolites present into the extracts could participate to the process. This paper aims to clarify the reducing action of single pure natural compounds usually present in plant tissues and to obtain a stable and reproducible protocol for NPs synthesis.

  8. Ultrasound-assisted microwave preparation of Ag-doped CdS nanoparticles.

    PubMed

    Ma, Jun; Tai, Guo'an; Guo, Wanlin

    2010-03-01

    Ag-doped CdS nanoparticles were synthesized by an ultrasound-assisted microwave synthesis method. The X-ray diffraction patterns reveal a structural evolution from cubic to hexagonal with increasing molar ratios of Ag(+)/Cd(2+) from 0% to 5%. It shows that the Ag-doped hexagonal CdS nanoparticles are polycrystal. The X-ray photoelectron spectroscopy of the CdS nanoparticles doping with 5% Ag(+) shows that the doped Ag in CdS is metallic. Simultaneously, the characteristic Raman peaks of the CdS nanoparticles enhance with increasing Ag(+) concentrations. The photocatalytic activity of different Ag-doped samples show a reasonable change due to different ratios of Ag which doped into CdS. Copyright 2009 Elsevier B.V. All rights reserved.

  9. Fungus-mediated synthesis of silver nanoparticles and their activity against pathogenic fungi in combination with fluconazole.

    PubMed

    Gajbhiye, Monali; Kesharwani, Jayendra; Ingle, Avinash; Gade, Aniket; Rai, Mahendra

    2009-12-01

    Silver nanoparticles (Ag-NPs) are known to have inhibitory and bactericidal effects. Resistance of fungal infections has emerged in recent years and is a major health problem. Here, we report the extracellular biosynthesis of Ag-NPs using a common fungus, Alternaria alternata. Also in this study, these nanoparticles were evaluated for their part in increasing the antifungal activity of fluconazole against Phoma glomerata, Phoma herbarum, Fusarium semitectum, Trichoderma sp., and Candida albicans. The antifungal activity of fluconazole was enhanced against the test fungi in the presence of Ag-NPs. Fluconazole in combination with Ag-NPs showed the maximum inhibition against C. albicans, which was confirmed from the increase in fold area of inhibition, followed by P. glomerata and Trichoderma sp., which showed less increase in the fold area, whereas no significant enhancement of activity was found against P. herbarum and F. semitectum. The antifungal activity of fluconazole was enhanced in presence of silver nanoparticles against the test fungi. Fluconazole in combination with Ag-NPs showed the maximum inhibition against C. albicans, followed by P. glomerata and Trichoderma sp. No significant enhancement of activity was found against P. herbarum and F. semitectum.

  10. Biosynthesis, Characterization, and Bioactivities Evaluation of Silver and Gold Nanoparticles Mediated by the Roots of Chinese Herbal Angelica pubescens Maxim

    NASA Astrophysics Data System (ADS)

    Markus, Josua; Wang, Dandan; Kim, Yeon-Ju; Ahn, Sungeun; Mathiyalagan, Ramya; Wang, Chao; Yang, Deok Chun

    2017-01-01

    A facile synthesis and biological applications of silver (DH-AgNps) and gold nanoparticles (DH-AuNps) mediated by the aqueous extract of Angelicae Pubescentis Radix (Du Huo) are explored. Du Huo is a medicinal root belonging to Angelica pubescens Maxim which possesses anti-inflammatory, analgesic, and antioxidant properties. The absorption spectra of nanoparticles in varying root extract and metal ion concentration, pH, reaction temperatures, and time were recorded by ultraviolet-visible (UV-Vis) spectroscopy. The presence of DH-AgNps and DH-AuNps was confirmed from the surface plasmon resonance intensified at 414 and 540 nm, respectively. Field emission transmission electron micrograph (FE-TEM) analysis revealed the formation of quasi-spherical DH-AgNps and spherical icosahedral DH-AuNps. These novel DH-AgNps and DH-AuNps maintained an average crystallite size of 12.48 and 7.44 nm, respectively. The biosynthesized DH-AgNps and DH-AuNps exhibited antioxidant activity against 2,2-diphenyl-1-picrylhydrzyl (DPPH) radicals and the former exhibited antimicrobial activity against clinical pathogens including Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella enterica. The expected presence of flavonoids, sesquiterpenes, and phenols on the nanoparticle surface were conjectured to grant protection against aggregation and free radical scavenging activity. DH-AgNps and DH-AuNps were further investigated for their cytotoxic properties in RAW264.7 macrophages for their potential application as drug carriers to sites of inflammation. In conclusion, this green synthesis is favorable for the advancement of plant mediated nano-carriers in drug delivery systems, cancer diagnostic, and medical imaging.

  11. Toxicity of Citrate-Capped Silver Nanoparticles in Common Carp (Cyprinus carpio)

    PubMed Central

    Lee, Byoungcheun; Duong, Cuong Ngoc; Cho, Jaegu; Lee, Jaewoo; Kim, Kyungtae; Seo, Youngrok; Kim, Pilje; Choi, Kyunghee; Yoon, Junheon

    2012-01-01

    Juvenile common carp (Cyprinus carpio) were used as a model to investigate acute toxicity and oxidative stress caused by silver nanoparticles (Ag-NPs). The fish were exposed to different concentrations of Ag-NPs for 48 h and 96 h. After exposure, antioxidant enzyme levels were measured, including glutathione-S-transferase (GST), superoxidase dismutase, and catalase (CAT). Other biochemical parameters and histological abnormalities in different tissues (i.e., the liver, gills, and brain) were also examined. The results showed that Ag-NPs agglomerated in freshwater used during the exposure experiments, with particle size remaining <100 nm. Ag-NPs had no lethal effect on fish after 4 days of exposure. Biochemical analysis showed that enzymatic activities in the brain of the fish exposed to 200 μg/L of Ag-NPs were significantly reduced. Varied antioxidant enzyme activity was recorded in the liver and gills. Varied antioxidant enzyme activity was recorded for CAT in the liver and GST in the gills of the fish. However, the recovery rate of fish exposed to 200 μg/L of Ag-NPs was slower than when lower particle concentrations were used. Other biochemical indices showed no significant difference, except for NH3 and blood urea nitrogen concentrations in fish exposed to 50 μg/L of Ag-NPs. This study provides new evidence about the effects of nanoparticles on aquatic organisms. PMID:23093839

  12. Effects of Systematic Variation in Size and Surface Coating of Silver Nanoparticles on Their In Vitro Toxicity to Macrophage RAW 264.7 Cells.

    PubMed

    Makama, Sunday; Kloet, Samantha K; Piella, Jordi; van den Berg, Hans; de Ruijter, Norbert C A; Puntes, Victor F; Rietjens, Ivonne M C M; van den Brink, Nico W

    2018-03-01

    In literature, varying and sometimes conflicting effects of physicochemical properties of nanoparticles (NPs) are reported on their uptake and effects in organisms. To address this, small- and medium-sized (20 and 50 nm) silver nanoparticles (AgNPs) with specified different surface coating/charges were synthesized and used to systematically assess effects of NP-properties on their uptake and effects in vitro. Silver nanoparticles were fully characterized for charge and size distribution in both water and test media. Macrophage cells (RAW 264.7) were exposed to these AgNPs at different concentrations (0-200 µg/ml). Uptake dynamics, cell viability, induction of tumor necrosis factor (TNF)-α, ATP production, and reactive oxygen species (ROS) generation were assessed. Microscopic imaging of living exposed cells showed rapid uptake and subcellular cytoplasmic accumulation of AgNPs. Exposure to the tested AgNPs resulted in reduced overall viability. Influence of both size and surface coating (charge) was demonstrated, with the 20-nm-sized AgNPs and bovine serum albumin (BSA)-coated (negatively charged) AgNPs being slightly more toxic. On specific mechanisms of toxicity (TNF-α and ROS production) however, the AgNPs differed to a larger extent. The highest induction of TNF-α was found in cells exposed to the negatively charged AgNP_BSA, both sizes (80× higher than control). Reactive oxygen species induction was only significant with the 20 nm positively charged AgNP_Chit.

  13. Toxic behavior of silver and zinc oxide nanoparticles on environmental microorganisms.

    PubMed

    Dhas, Sindhu Priya; Shiny, Punalur John; Khan, Sudheer; Mukherjee, Amitava; Chandrasekaran, Natrajan

    2014-09-01

    Silver and zinc oxide nanoparticles (Ag and ZnO NPs) are widely used as antimicrobial agents. However, their potential toxicological impact on environmental microorganisms is largely unexplored. The aim of this work was to investigate the sensitivity and adaptability of five bacterial species isolated from sewage towards Ag and ZnO NPs. The bacterial species were exposed to increasing concentration of nanoparticles and the growth inhibitory effect, exopolysaccharides (EPSs) and extracellular proteins (ECPs) productions were determined. The involvement of surface charge in nanoparticles toxicity was also determined. The bacterial species were constantly exposed to nanoparticles to determine the adaptation behavior toward nanoparticles. The nanoparticles exhibited remarkable growth inhibitory effect on tested bacterial species. The toxicity of nanoparticles was found to be strongly dependent on surface charge effects. Though, these organisms are highly sensitive to Ag and ZnO NPs, the continuous exposure to these nanoparticles leads to moderate adaptation of bacterial species and the adapted bacterial species convert the highly toxic nano form to less toxic microform. Finally we predict that the continuing applications of nanoparticles in consumer products may lead to the development of nanoparticles resistant bacterial strains in future. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Synthesis and Characterization of Composite Hydroxyapatite-Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Charlena; Nuzulia, N. A.; Handika

    2017-03-01

    Hydroxyapatite (HAp) is commonly used as bone implant coating recently; however, the material has disadvantage such as lack of antibacterial properties, that can cause an bacterial infection. Addition of silver nanoparticles is expected to be able to provide antibacterial properties. Silver nanoparticles was obtained by reduction of AgNO3 using glucose monohydrate with microwave heating at 100p for 4 minutes. The composite of hydroxyapatite-silver nanoparticles was synthesized using chemical methods by coprecipitation suspension of Ca(OH)2 with (NH4)HPO4, followed by adding silver nanoparticles solution. The size of the synthesized silver nanoparticles was 30-50 nm and exhibited good antibacterial activity. Nevertheless, when it was composited with HAp to form HAp-AgNPs, there was no antibacterial activity due to very low concentration of silver nanoparticles. This was indicated by the absence of silver nanoparticles diffraction patterns. Infrared spectra indicated the presence of chemical shift and the results of scanning electron microscope showed size of the HAp-AgNPs composite was smaller than that of the HAp. This showed the interaction between HAp and the silver nanoparticles.

  15. Silver nanoparticles embedded mesoporous SiO2 nanosphere: an effective anticandidal agent against Candida albicans 077

    NASA Astrophysics Data System (ADS)

    Qasim, M.; Singh, Braj R.; Naqvi, A. H.; Paik, P.; Das, D.

    2015-07-01

    Candida albicans is a diploid fungus that causes common infections such as denture stomatitis, thrush, urinary tract infections, etc. Immunocompromised patients can become severely infected by this fungus. Development of an effective anticandidal agent against this pathogenic fungus, therefore, will be very useful for practical application. In this work, Ag-embedded mesoporous silica nanoparticles (mSiO2@AgNPs) have successfully been synthesized and their anticandidal activities against C. albicans have been studied. The mSiO2@AgNPs nanoparticles (d ˜ 400 nm) were designed using pre-synthesized Ag nanoparticles and tetraethyl orthosilicate (TEOS) as a precursor for SiO2 in the presence of cetyltrimethyl ammonium bromide (CTAB) as an easily removable soft template. A simple, cost-effective, and environmentally friendly approach has been adopted to synthesize silver (Ag) nanoparticles using silver nitrate and leaf extract of Azadirachta indica. The mesopores, with size-equivalent diameter of the micelles (d = 4-6 nm), were generated on the SiO2 surface by calcination after removal of the CTAB template. The morphology and surface structure of mSiO2@AgNPs were characterized through x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), particle size analysis (PSA), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) and high-resolution transmission electron microscopy (HRTEM). The HRTEM micrograph reveals the well-ordered mesoporous structure of the SiO2 sphere. The antifungal activities of mSiO2@AgNPs on the C. albicans cell have been studied through microscopy and are seen to increase with increasing dose of mSiO2@AgNPs, suggesting mSiO2@AgNPs to be a potential antifungal agent for C. albicans 077.

  16. Physicochemical and antibacterial characterization of ionocity Ag/Cu powder nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nowak, A., E-mail: ana.maria.nowak@gmail.com; Silesian Center for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów; Szade, J.

    Metal ion in bimetallic nanoparticles has shown vast potential in a variety of applications. In this paper we show the results of physical and chemical investigations of powder Ag/Cu nanoparticles obtained by chemical synthesis. Transmission electron microscopy (TEM) experiment indicated the presence of bimetallic nanoparticles in the agglomerated form. The average size of silver and copper nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu) basing on the X-ray diffraction (XRD) data. X-ray photoelectron (XPS) and Raman spectroscopies revealed the existence of metallic silver and copper as well as Cu{sub 2}O and CuO being a part of the nanoparticles. Moreover,more » UV–Vis spectroscopy showed surface alloy of Ag and Cu while Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Energy Dispersive X-ray Spectroscopy (EDX) showed heterogeneously distributed Ag structures placed on spherical Cu nanoparticles. The tests of antibacterial activity show promising killing/inhibiting growth behaviour for Gram positive and Gram negative bacteria. - Highlights: • Ag/Cu nanoparticles were obtained in the powder form. • The average size of nanoparticles is 17.1(4) nm (Ag) and 28.9(2) nm (Cu). • Ag/Cu powder nanoparticle shows promising antibacterial properties.« less

  17. Retention of silver nano-particles and silver ions in calcareous soils: Influence of soil properties.

    PubMed

    Rahmatpour, Samaneh; Shirvani, Mehran; Mosaddeghi, Mohammad R; Bazarganipour, Mehdi

    2017-05-15

    The rapid production and application of silver nanoparticles (AgNPs) have led to significant release of AgNPs into the terrestrial environments. Once released into the soil, AgNPs could enter into different interactions with soil particles which play key roles in controlling the fate and transport of these nanoparticles. In spite of that, experimental studies on the retention of AgNPs in soils are very scarce. Hence, the key objective of this research was to find out the retention behavior of AgNPs and Ag(I) ions in a range of calcareous soils. A second objective was to determine the extent to which the physico-chemical properties of the soils influence the Ag retention parameters. To this end, isothermal batch experiments were used to determine the retention of Poly(vinylpyrrolidinone)-capped AgNPs (PVP-AgNPs) and Ag(I) ions by nine calcareous soils with a diversity of physico-chemical properties. The results revealed that the retention data for both PVP-AgNPs and Ag(I) ions were well described by the classical Freundlich and Langmuir isothermal equations. The retention of PVP-AgNPs and Ag(I) ions was positively correlated to clay and organic carbon (OC) contents as well as electrical conductivity (EC), pH, and cation exchange capacity (CEC) of the soils. Due to multicolinearity among the soil properties, principal component analysis (PCA) was used to group the soil properties which affect the retention of PVP-AgNPs and Ag(I) ions. Accordingly, we identified two groups of soil properties controlling retention of PVP-AgNPs and Ag(I) ions in the calcareous soils. The first group comprised soil solid phase parameters like clay, OC, and CEC, which generally control hetero-aggregation and adsorption reactions and the second group included soil solution variables such as EC and pH as well as Cl - and Ca 2+ concentrations, which are supposed to mainly affect homo-aggregation and precipitation reactions. Copyright © 2017. Published by Elsevier Ltd.

  18. Biosynthesis of silver nanoparticles using Caesalpinia ferrea (Tul.) Martius extract: physicochemical characterization, antifungal activity and cytotoxicity

    PubMed Central

    2018-01-01

    Background Green synthesis is an ecological technique for the production of well characterized metallic nanoparticles using plants. This study investigated the synthesis of silver nanoparticles (AgNPs) using a Caesalpinia ferrea seed extract as a reducing agent. Methods The formation of AgNPs was identified by instrumental analysis, including ultraviolet–visible (UV–Vis) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) of the AgNPs, and surface-enhanced Raman scattering (SERS) spectra of rhodamine-6G (R6G). We studied the physicochemical characterization of AgNPs, evaluated them as an antifungal agent against Candida albicans, Candida kruzei, Candida glabrata and Candida guilliermondii, and estimated their minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values. Lastly, this study evaluated the cytotoxicity of the AgNPs in murine L929 fibroblasts cells using an MTT assay. Results The UV–Vis spectroscopy, SERS, SEM and XRD results confirmed the rapid formation of spheroidal 30–50 nm AgNPs. The MIC and MFC values indicated the antifungal potential of AgNPs against most of the fungi studied and high cell viability in murine L929 fibroblasts. In addition, this study demonstrated that C. ferrea seed extracts may be used for the green synthesis of AgNPs at room temperature for the treatment of candidiasis. PMID:29576936

  19. Detection of silver nanoparticles in seawater at ppb levels using UV-visible spectrophotometry with long path cells.

    PubMed

    Lodeiro, Pablo; Achterberg, Eric P; El-Shahawi, Mohammad S

    2017-03-01

    Silver nanoparticles (AgNPs) are emerging contaminants that are difficult to detect in natural waters. UV-visible spectrophotometry is a simple technique that allows detection of AgNPs through analysis of their characteristic surface plasmon resonance band. The detection limit for nanoparticles using up to 10cm path length cuvettes with UV-visible spectrophotometry is in the 0.1-10ppm range. This detection limit is insufficiently low to observe AgNPs in natural environments. Here we show how the use of capillary cells with an optical path length up to 200cm, forms an excellent technique for rapid detection and quantification of non-aggregated AgNPs at ppb concentrations in complex natural matrices such as seawater. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Silver nanoparticles: a novel radiation sensitizer for glioma?

    NASA Astrophysics Data System (ADS)

    Liu, Peidang; Huang, Zhihai; Chen, Zhongwen; Xu, Ruizhi; Wu, Hao; Zang, Fengchao; Wang, Cailian; Gu, Ning

    2013-11-01

    Malignant gliomas are the most common primary intracranial tumors with a dismal prognosis. Previous investigations by our group demonstrated the radiosensitizing effect of silver nanoparticles (AgNPs) on glioma cells in vitro. The goal of the present study was to evaluate the efficacy of intratumoral administration of AgNPs in combination with a single dose of ionizing radiation at clinically relevant MV energies for the treatment of C6 glioma-bearing rats. AgNPs (10 or 20 μg/10 μl) were stereotactically administered on day 8 after tumor implantation. One day after AgNP injection, rats bearing glioma received 10 Gy radiation. The mean survival times were 100.5 and 98 days, the corresponding percent increase in life spans was 513.2% and 497.7%, and the cure rates were 41.7 and 38.5% at 200 days for the 10 and 20 μg AgNPs and radiation combination groups, respectively. In contrast, the mean survival times for irradiated controls, 10 and 20 μg AgNPs alone, and untreated controls were 24.5, 16.1, 19.4, and 16.4 days, respectively. Furthermore, a cooperative antiproliferative and proapoptotic effect was obtained when gliomas were treated with AgNPs followed by radiotherapy. Our results showed the therapeutic efficacy of AgNPs in combination with radiotherapy without apparent systemic toxicity, suggesting the clinical potential of AgNPs in improving the outcome of malignant glioma radiotherapy.Malignant gliomas are the most common primary intracranial tumors with a dismal prognosis. Previous investigations by our group demonstrated the radiosensitizing effect of silver nanoparticles (AgNPs) on glioma cells in vitro. The goal of the present study was to evaluate the efficacy of intratumoral administration of AgNPs in combination with a single dose of ionizing radiation at clinically relevant MV energies for the treatment of C6 glioma-bearing rats. AgNPs (10 or 20 μg/10 μl) were stereotactically administered on day 8 after tumor implantation. One day after Ag