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Sample records for ag nps toxicity

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

    PubMed Central

    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 110nm 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 110nm 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. PMID:26152688

  2. 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.

  3. Silver sulfide nanoparticles (Ag2S-NPs) are taken up by plants and are phytotoxic.

    PubMed

    Wang, Peng; Menzies, Neal W; Lombi, Enzo; Sekine, Ryo; Blamey, F Pax C; Hernandez-Soriano, Maria C; Cheng, Miaomiao; Kappen, Peter; Peijnenburg, Willie J G M; Tang, Caixian; Kopittke, Peter M

    2015-01-01

    Silver nanoparticles (NPs) are used in more consumer products than any other nanomaterial and their release into the environment is unavoidable. Of primary concern is the wastewater stream in which most silver NPs are transformed to silver sulfide NPs (Ag2S-NPs) before being applied to agricultural soils within biosolids. While Ag2S-NPs are assumed to be biologically inert, nothing is known of their effects on terrestrial plants. The phytotoxicity of Ag and its accumulation was examined in short-term (24 h) and longer-term (2-week) solution culture experiments with cowpea (Vigna unguiculata L. Walp.) and wheat (Triticum aestivum L.) exposed to Ag2S-NPs (0-20 mg Ag L(-1)), metallic Ag-NPs (0-1.6 mg Ag L(-1)), or ionic Ag (AgNO3; 0-0.086 mg Ag L(-1)). Although not inducing any effects during 24-h exposure, Ag2S-NPs reduced growth by up to 52% over a 2-week period. This toxicity did not result from their dissolution and release of toxic Ag(+) in the rooting medium, with soluble Ag concentrations remaining below 0.001 mg Ag L(-1). Rather, Ag accumulated as Ag2S in the root and shoot tissues when plants were exposed to Ag2S-NPs, consistent with their direct uptake. Importantly, this differed from the form of Ag present in tissues of plants exposed to AgNO3. For the first time, our findings have shown that Ag2S-NPs exert toxic effects through their direct accumulation in terrestrial plant tissues. These findings need to be considered to ensure high yield of food crops, and to avoid increasing Ag in the food chain.

  4. 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

  5. Integrated mRNA and micro RNA profiling reveals epigenetic mechanism of differential sensitivity of Jurkat T cells to AgNPs and Ag ions.

    PubMed

    Eom, Hyun-Jeong; Chatterjee, Nivedita; Lee, Jeongsoo; Choi, Jinhee

    2014-08-17

    In our previous in vitro study of the toxicity on silver nanoparticles (AgNPs), we observed a dramatically higher sensitivity of Jurkat T cells to AgNPs than to Ag ions, and DNA damage and apoptosis were found to be involved in that toxicity. In this study, to understand underlying mechanism of different sensitivity of Jurket T cells to AgNPs and Ag ions, mRNA microarray and micro RNA microarray were concomitantly conducted on AgNPs and Ag ions exposed Jurkat T cells. Surprisingly only a small number of genes were differentially expressed by exposure to each of the silver (15 altered mRNA by AgNPs exposure, whereas 4 altered mRNA by Ag ions exposure, as determined 1.5-fold change as the cut-off value). miRNA microarray revealed that the expression of 63 miRNAs was altered by AgNPs exposure, whereas that of 32 miRNAs was altered by Ag ions exposure. An integrated analysis of mRNA and miRNA expression revealed that the expression of hsa-miR-219-5p, was negatively correlated with the expression of metallothionein 1F (MT1F) and tribbles homolog 3 (TRIB3), in cells exposed to AgNPs; whereas, the expression of hsa-miR-654-3p was negatively correlated with the expression of mRNA, endonuclease G-like 1 (EDGL1) in cells exposed to Ag ions. Network analysis were further conducted on mRNA-miRNA pairs, which revealed that miR-219-5p-MT1F and -TRIB3 pairs by AgNPs are being involved in various cellular processes, such as, oxidative stress, cell cycle and apoptosis, whereas, miR-654-3p and ENDOGL1 pair by Ag ions generated a much simpler network. The putative target genes of AgNPs-induced miR-504, miR-33 and miR-302 identified by Tarbase 6.0 are also found to be involved in DNA damage and apoptosis. These results collectively suggest that distinct epigenetic regulation may be an underlying mechanism of different sensitivity of Jurkat T cells to AgNPs and Ag ion. Further identification of putative target genes of DE miRNA by AgNPs and Ag ions may provide additional clues for the

  6. 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

  7. Jointed toxicity of TiO2 NPs and Cd to rice seedlings: NPs alleviated Cd toxicity and Cd promoted NPs uptake.

    PubMed

    Ji, Ye; Zhou, Yun; Ma, Chuanxin; Feng, Yan; Hao, Yi; Rui, Yukui; Wu, Wenhao; Gui, Xin; Le, Van Nhan; Han, Yaning; Wang, Yingcai; Xing, Baoshan; Liu, Liming; Cao, Weidong

    2017-01-01

    Previous studies have reported that nanoparticles (NPs) and heavy metals are toxic to the environment. However, the jointed toxicity is not yet well understood. This study was aimed to investigate the combined toxicity of TiO2 NPs and the heavy metal cadmium (Cd) to plants. Rice (Oryzasativa L.) was selected as the target plant. The rice seedlings were randomly separated into 12 groups and treated with CdCl2 (0, 10 and 20 mg/L) and TiO2 NPs (0, 10, 100 and 1000 mg/L). The plant height, biomass and root length indicated significant toxicity of Cd to the growth, but TiO2 NPs exhibited the potential ability to alleviate the Cd toxicity. Transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) confirmed the existence of TiO2 NPs in plants. Elemental analysis of Ti and Cd suggested that the presences of Cd significantly decreased the Ti accumulation in the rice roots in the co-exposure treatments. Interestingly, TiO2 NPs could lower the Cd uptake and distribution in rice roots and leaves. The results of antioxidant enzyme activity, lipid peroxide as well as phytohormones varied in the different treatments. Comparing with the Cd alone treatment, the net photosynthetic rate and chlorophyll content were significantly increased in the co-exposure treatments, suggesting that TiO2 NPs could tremendously reduce the Cd toxicity.

  8. The preparation and antibacterial effects of dopa-cotton/AgNPs

    NASA Astrophysics Data System (ADS)

    Xu, Hong; Shi, Xue; Ma, Hui; Lv, Yihang; Zhang, Linping; Mao, Zhiping

    2011-05-01

    Silver nanoparticles (AgNPs) have been known to have powerful antibacterial activity. In this paper, in situ generation of AgNPs on the surface of dopamine modified cotton fabrics (dopa-cotton/AgNPs) in aqueous solution under room temperature is presented. X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscope (FE-SEM) were used to analyze the surface chemical composition and the morphology of the modified cotton fabrics, respectively. The results indicated that the surface of cotton fabrics was successfully coated with polydopamine and AgNPs. The cotton fabrics with AgNPs showed durable antibacterial activity.

  9. 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.

  10. Fabrication of Au@Ag core-shell NPs as enhanced CT contrast agents with broad antibacterial properties.

    PubMed

    Huo, Da; He, Jian; Li, Hui; Yu, Haiping; Shi, Tingting; Feng, Yahui; Zhou, Zhengyang; Hu, Yong

    2014-05-01

    Au@Ag core-shell nanoparticles (NPs) integrating both antibacterial and X-ray attenuation capabilities were facilely synthesized in aqueous solution. These NPs modified with methoxy-PEG-SH (m-PEG) on the surface rendered them favorable dispersity and stability in water, resulting in enhancement of their blood circulation time. X-ray photoelectron spectroscope (XPS) and high-resolution transmission electron microscope (HRTEM) results confirmed the core-shell structure of m-PEG-Au@Ag NPs. The m-PEG-Au@Ag NPs showed low cytotoxicity and strong X-ray absorption potency in vitro. Further in vivo study showed that as-synthesized NPs offered a pronounced contrast and prolonged their circulation time in the blood stream with negligible toxic effect in vivo. Besides, m-PEG-Au@Ag NPs had significant bacteriostatic effect toward common bacteria like Escherichia coli and Staphylococcus aureus as demonstrated by broth dilution assay. Given their low-cytotoxicity and high CT attenuation efficacy, m-PEG-Au@Ag NPs had a promising potential for use as CT enhancing and antibacterial agents.

  11. Nanosilver as a disinfectant in dental unit waterlines: Assessment of the physicochemical transformations of the AgNPs.

    PubMed

    Gitipour, Alireza; Al-Abed, Souhail R; Thiel, Stephen W; Scheckel, Kirk G; Tolaymat, Thabet

    2017-04-01

    Dental unit water lines (DUWL) are susceptible to biofilm development and bacterial growth leading to water contamination, causing health and ecological effects. This study monitors the interactions between a commonly used nanosilver disinfectant (ASAP-AGX-32, an antimicrobial cleaner for dental units, 0.0032% Ag) and biofilm development in DUWL. To simulate the disinfection scenario, an in-house DUWL model was assembled and biofilm accumulation was allowed. Subsequent to biofilm development, the disinfection process was performed according to the manufacturer's instructions. The pristine nanosilver particles in the cleaner measured between 3 and 5 nm in diameter and were surrounded by a stabilizing polymer. However, the polymeric stabilizing agent diminished over the disinfection process, initiating partial AgNPs aggregation. Furthermore, surface speciation of the pristine AgNPs were identified as primarily AgO, and after the disinfection process, transformations to AgCl were observed. The physicochemical characteristics of AgNPs are known to govern their fate, transport and environmental implications. Hence, knowledge of the AgNPs characteristics after the disinfection process (usage scenario) is of significance. This study demonstrates the adsorption of AgNPs onto biofilm surfaces and, therefore, will assist in illustration of the toxicity mechanisms of AgNPs to bacteria and biofilms. This work can be an initial step in better understanding how AgNPs transform depending on the conditions they are exposed to during their lifetime. Until this date, most research has been focused on assessing the impacts of pristine (lab synthesized) nanomaterials on various systems. However, it is our belief that nanoparticles may undergo transformations during usage, which must be taken into consideration. Furthermore, this experiment is unique as it was conducted with a commonly used, commercially available nanosilver suspension leading to more realistic and applicable findings.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27615743

  13. 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.

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

    PubMed

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

    2016-09-12

    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.

  15. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles: part 2-toxicity and Ag speciation.

    PubMed

    Bone, Audrey J; Colman, Benjamin P; Gondikas, Andreas P; Newton, Kim M; Harrold, Katherine H; Cory, Rose M; Unrine, Jason M; Klaine, Stephen J; Matson, Cole W; Di Giulio, Richard T

    2012-07-03

    To study the effects of complex environmental media on silver nanoparticle (AgNP) toxicity, AgNPs were added to microcosms with freshwater sediments and two species of aquatic plants (Potamogeton diversifolius and Egeria densa), followed by toxicity testing with microcosm surface water. Microcosms were designed with four environmental matrices in order to determine the contribution of each environmental compartment to changes in toxicity: water only (W), water + sediment (WS), water + plants (WP), and water + plants + sediment (WPS). Silver treatments included AgNPs with two different coatings, gum arabic (GA-AgNPs) or polyvinylpyrollidone (PVP-AgNPs), as well as AgNO(3). Water samples taken from the microcosms at 24 h postdosing were used in acute toxicity tests with two standard model organisms, early life stage zebrafish (Danio rerio) and Daphnia magna. Speciation of Ag in these samples was analyzed using Ag L3-edge X-ray absorption near edge spectroscopy (XANES). Silver speciation patterns for the nanoparticle treatments varied significantly by coating type. While PVP-AgNPs were quite stable and resisted transformation across all matrices (>92.4% Ag(0)), GA-AgNP speciation patterns suggest significantly higher transformation rates, especially in treatments with plants (<69.2% and <58.8% Ag(0) in WP and WPS, respectively) and moderately increased transformation with sediments (<85.6% Ag(0)). Additionally, the presence of plants in the microcosms (with and without sediments) reduced both the concentration of Ag in the water column and toxicity for all Ag treatments. Reductions in toxicity may have been related to decreased water column concentrations as well as changes in the surface chemistry of the particles induced by organic substances released from the plants.

  16. 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.

  17. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells.

    PubMed

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag.

  18. Mechanisms of Toxicity of Ag Nanoparticles in Comparison to Bulk and Ionic Ag on Mussel Hemocytes and Gill Cells

    PubMed Central

    Katsumiti, Alberto; Gilliland, Douglas; Arostegui, Inmaculada; Cajaraville, Miren P.

    2015-01-01

    Silver nanoparticles (Ag NPs) are increasingly used in many products and are expected to end up in the aquatic environment. Mussels have been proposed as marine model species to evaluate NP toxicity in vitro. The objective of this work was to assess the mechanisms of toxicity of Ag NPs on mussel hemocytes and gill cells, in comparison to ionic and bulk Ag. Firstly, cytotoxicity of commercial and maltose stabilized Ag NPs was screened in parallel with the ionic and bulk forms at a wide range of concentrations in isolated mussel cells using cell viability assays. Toxicity of maltose alone was also tested. LC50 values were calculated and the most toxic Ag NPs tested were selected for a second step where sublethal concentrations of each Ag form were tested using a wide array of mechanistic tests in both cell types. Maltose-stabilized Ag NPs showed size-dependent cytotoxicity, smaller (20 nm) NPs being more toxic than larger (40 and 100 nm) NPs. Maltose alone provoked minor effects on cell viability. Ionic Ag was the most cytotoxic Ag form tested whereas bulk Ag showed similar cytotoxicity to the commercial Ag NPs. Main mechanisms of action of Ag NPs involved oxidative stress and genotoxicity in the two cell types, activation of lysosomal AcP activity, disruption of actin cytoskeleton and stimulation of phagocytosis in hemocytes and increase of MXR transport activity and inhibition of Na-K-ATPase in gill cells. Similar effects were observed after exposure to ionic and bulk Ag in the two cell types, although generally effects were more marked for the ionic form. In conclusion, results suggest that most observed responses were due at least in part to dissolved Ag. PMID:26061169

  19. Fabrication LSPR sensor chip of Ag NPs and their biosensor application based on interparticle coupling

    NASA Astrophysics Data System (ADS)

    Ghodselahi, T.; Neishaboorynejad, T.; Arsalani, S.

    2015-07-01

    We introduce a simple method to synthesize localized surface plasmon resonance (LSPR) sensor chip of Ag NPs on the hydrogenated amorphous carbon by co-deposition of RF-Sputtering and RF-PECVD. The X-ray photoelectron spectroscopy revealed the content of Ag and C atoms. X-ray diffraction profile and atomic force microscopy indicate that the Ag NPs have fcc crystal structure and spherical shape and by increasing deposition time, particle sizes do not vary and only Ag NPs aggregation occurs, resulting in LSPR wavelength shift. Firstly, by increasing Ag NPs content, in-plan interparticles coupling is dominant and causes redshift in LSPR. At the early stage of agglomeration, out-plane coupling occurs and in-plane coupling is reduced, resulting a blueshift in the LSPR. By further increasing of Ag NPs content, agglomeration is completed on the substrate and in-plan coupling rises, resulting significant redshift in the LSPR. Results were used to implement biosensor application of chips. Detection of DNA primer at fM concentration was achieved based on breaking interparticles coupling of Ag NPs. A significant wavelength shift sensitivity of 30 nm and a short response time of 30 min were obtained, where both of these are prerequisite for biosensor applications.

  20. Exposure Medium: Key in Identifying Free Ag+ as the Exclusive Species of Silver Nanoparticles with Acute Toxicity to Daphnia magna

    PubMed Central

    Shen, Mo-Hai; Zhou, Xiao-Xia; Yang, Xiao-Ya; Chao, Jing-Bo; Liu, Rui; Liu, Jing-Fu

    2015-01-01

    It is still not very clear what roles the various Ag species play in the toxicity of silver nanoparticles (AgNPs). In this study, we found that traditional exposure media result in uncontrollable but consistent physicochemical transformation of AgNPs, causing artifacts in determination of median lethal concentration (LC50) and hindering the identification of Ag species responsible for the acute toxicity of AgNPs to Daphnia magna. This obstacle was overcome by using 8 h exposure in 0.1 mmol L−1 NaNO3 medium, in which we measured the 8-h LC50 of seven AgNPs with different sizes and coatings, and determined the concentrations of various Ag species. The LC50 as free Ag+ of the seven AgNPs (0.37–0.44 μg L−1) agreed very well with that of AgNO3 (0.40 μg L−1), and showed the lowest value compared to that as total Ag, total Ag+, and dissolved Ag, demonstrating free Ag+ is exclusively responsible for the acute toxicity of AgNPs to D. magna, while other Ag species in AgNPs have no contribution to the acute toxicity. Our results demonstrated the great importance of developing appropriate exposure media for evaluating risk of nanomaterials. PMID:25858866

  1. Exposure Medium: Key in Identifying Free Ag+ as the Exclusive Species of Silver Nanoparticles with Acute Toxicity to Daphnia magna

    NASA Astrophysics Data System (ADS)

    Shen, Mo-Hai; Zhou, Xiao-Xia; Yang, Xiao-Ya; Chao, Jing-Bo; Liu, Rui; Liu, Jing-Fu

    2015-04-01

    It is still not very clear what roles the various Ag species play in the toxicity of silver nanoparticles (AgNPs). In this study, we found that traditional exposure media result in uncontrollable but consistent physicochemical transformation of AgNPs, causing artifacts in determination of median lethal concentration (LC50) and hindering the identification of Ag species responsible for the acute toxicity of AgNPs to Daphnia magna. This obstacle was overcome by using 8 h exposure in 0.1 mmol L-1 NaNO3 medium, in which we measured the 8-h LC50 of seven AgNPs with different sizes and coatings, and determined the concentrations of various Ag species. The LC50 as free Ag+ of the seven AgNPs (0.37-0.44 μg L-1) agreed very well with that of AgNO3 (0.40 μg L-1), and showed the lowest value compared to that as total Ag, total Ag+, and dissolved Ag, demonstrating free Ag+ is exclusively responsible for the acute toxicity of AgNPs to D. magna, while other Ag species in AgNPs have no contribution to the acute toxicity. Our results demonstrated the great importance of developing appropriate exposure media for evaluating risk of nanomaterials.

  2. Highly Reproducible Ag NPs/CNT-Intercalated GO Membranes for Enrichment and SERS Detection of Antibiotics.

    PubMed

    Qu, Lu Lu; Liu, Ying-Ya; Liu, Ming-Kai; Yang, Guo-Hai; Li, Da-Wei; Li, Hai-Tao

    2016-10-05

    The increasing pollution of aquatic environments by antibiotics makes it necessary to develop efficient enrichment and sensitive detection methods for environmental antibiotics monitoring. In this work, silver nanoparticles and carbon nanotube-intercalated graphene oxide laminar membranes (Ag NPs/CNT-GO membranes) were successfully prepared for enrichment and surface-enhanced Raman scattering (SERS) detection of antibiotics. The prepared Ag NPs/CNT-GO membranes exhibited a high enrichment ability because of the π-π stacking and electrostatic interactions of GO toward antibiotic molecules, which enhanced the sensitivity of SERS measurements and enabled the antibiotics to be determined at sub-nM concentrations. In addition, the nanochannels created by the intercalation of CNTs into GO layers resulted in an 8-fold enhancement in the water permeance of Ag NPs/CNT-GO membranes compared to that of pure GO membranes. More importantly, the Ag NPs/CNT-GO membranes exhibited high reproducibility and long-term stability. The spot-to-spot variation in SERS intensity was less than 15%, and the SERS performance was maintained for at least 70 days. The Ag NPs/CNT-GO membranes were also used for SERS detection of antibiotics in real samples; the results showed that the characteristic peaks of antibiotics were obviously recognizable. Thus, the sensitive SERS detection of antibiotics based on Ag NPs/CNT-GO offers great potential for practical applications in environmental analysis.

  3. Novel Asymmetric Wettable AgNPs/Chitosan Wound Dressing: In Vitro and In Vivo Evaluation.

    PubMed

    Liang, Donghui; Lu, Zhong; Yang, Hao; Gao, Jingting; Chen, Rong

    2016-02-17

    A novel silver nanoparticles (AgNPs)/chitosan composite dressing with asymmetric wettability surfaces was successfully prepared via a simple two-step method for biomedical applications as wound healing materials. First, AgNPs were assembled into the chitosan sponge which was prepared by lyophilization process. Then one side of the sponge was modified by a thin layer of stearic acid. The incorporation of AgNPs into chitosan dressing could enhance the antibacterial activity against drug-sensitive and drug-resistant pathogenic bacteria. The asymmetric surface modification endows the dressing with both highly hydrophobic property and inherent hydrophilic nature of chitosan. The hydrophobic surface of the dressing shows waterproof and antiadhesion for contaminant properties, whereas the hydrophilic surface preserves its water-absorbing capability and efficiently inhibits the growth of bacteria. Furthermore, the AgNPs/chitosan composite dressing displays improved moisture retention and blood clotting ability compared to the unmodified dressings. Cytocompatibility test evaluated in vitro and in a wound infection model illustrates the nontoxic nature of the composite dressing. More importantly, the in vivo wound healing model evaluation in mice reveals that the asymmetric AgNPs/chitosan dressing promotes the wound healing and accelerates the reepithelialization and collagen deposition. The silver accumulation in mice body treated by the composite dressing is far lower than that of the clinically used Acasin nanosilver dressing treated mice. This work indicates the huge potential of the novel AgNPs/chitosan wound dressing with asymmetrical wettability for clinical use.

  4. Evaluation of genotoxic effect of silver nanoparticles (Ag-Nps) in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Tavares, Priscila; Balbinot, Fernanda; de Oliveira, Hugo Martins; Fagundes, Gabriela Elibio; Venâncio, Mireli; Ronconi, João Vitor Vieira; Merlini, Aline; Streck, Emílio L.; da Silva Paula, Marcos Marques; de Andrade, Vanessa Moraes

    2012-03-01

    Silver nanoparticles (Ag-NPs) are the most prominent nanoproducts. Due to their antimicrobial activity, they have been incorporated in different materials, such as catheters, clothes, electric home appliance, and many others. The genotoxicity of Ag-NPs (5-45 nm), in different concentrations and times of exposure, was evaluated by the comet assay in in vitro and in vivo conditions, respectively, using human peripheral blood and Swiss mice. The results showed the genotoxic effect of Ag-NPs in vitro , in all the doses tested in the initial hour of exposure, possibly through the reactive oxygen species generation. Nevertheless, the values for this damage decrease with time, indicating that the DNA may have been restored by the repair system. In the in vivo conditions, we found no genotoxicity of Ag-NPs in any hour of exposure and any dose investigated, which can be attributed to the activation of a cellular antioxidant network and the hydrophobic nature of Ag-NPs. Now, it is absolutely necessary to investigate the role of Ag-NPs in different cell lines in vivo.

  5. Toxicokinetics of Ag in the terrestrial isopod Porcellionides pruinosus exposed to Ag NPs and AgNO₃ via soil and food.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Morgan, A John; Kille, Peter; Svendsen, Claus; Jurkschat, Kerstin; Mosselmans, J Fred W; Soares, Amadeu M V M; Loureiro, Susana

    2016-03-01

    Silver nanoparticles (Ag NPs) have been used in numerous consumer products and may enter the soil through the land application of biosolids. However, little is known about the relationship between Ag NP exposure and their bioavailability for soil organisms. This study aims at comparing the uptake and elimination kinetics of Ag upon exposures to different Ag forms (NPs and ionic Ag (as AgNO3)) in the isopod Porcellionides pruinosus. Isopods were exposed to contaminated Lufa 2.2 soil or alder leaves as food. Uptake and elimination rate constants for soil exposure did not significantly differ between Ag NPs and ionic Ag at 30 and 60 mg Ag/kg. For dietary exposure, the uptake rate constant was up to 5 times higher for Ag NPs than for AgNO3, but this was related to feeding activity and exposure concentrations, while no difference in the elimination rate constants was found. When comparing both routes, dietary exposure resulted in lower Ag uptake rate constants but elimination rate constants did not differ. A fast Ag uptake was observed from both routes and most of the Ag taken up seemed not to be eliminated. Synchrotron X-ray fluorescence showed Ag in the S-cells of the hepatopancreas, thus supporting the observations from the kinetic experiment (i.e. low elimination). In addition, our results show that isopods have an extremely high Ag accumulation capacity, suggesting the presence of an efficient Ag storage compartment.

  6. Instantly AgNPs deposition through facile solventless technique for poly-functional cotton fabrics.

    PubMed

    Emam, Hossam E; Saleh, N H; Nagy, Khaled S; Zahran, M K

    2016-03-01

    Nowadays, functional clothes are employed for human body protection in addition to be fashionable clothes. Hence functionalization of clothes increases the attention of scientists and business. In the current study, poly-functional cotton fabric was carried out by instantly deposition of AgNPs using two solventless techniques namely; sorption and padding. Sorption technique was exhibited extremely high efficiency than padding one by ca. 10 times. By using the same concentrations of AgNO3, Ag content was ranged 69.3-6094.8 mg/kg and 33.8-609.3 mg/kg for sorption and padding, respectively. After AgNPs deposition, fabrics color was turned to gray-reddish yellow. By applying 5912.3 mgAg/kg fabric, bacterial reduction and UPF value were reached 99% and 12.59. Bacterial reduction and UPF were lessened to 90% and 10.19 after 20 washings. These findings proved that the direct AgNPs deposition into cotton using solventless/sorption technique is applicable in manufacturing of antibacterial/UV resistant fabrics with acquired decorative color.

  7. Green rapid biogenic synthesis of bioactive silver nanoparticles (AgNPs) using Pseudomonas aeruginosa.

    PubMed

    Busi, Siddhardha; Rajkumari, Jobina; Ranjan, Bibhuti; Karuganti, Sukumar

    2014-12-01

    The present work was focused on isolating a bacterial strain of Pseudomonas sp. with the ability to synthesise AgNPs rapidly. A strain of Pseudomonas aeruginosa designated JO was found to be a potential candidate for rapid synthesis of AgNPs with a synthesis time of 4h in light, at room temperature which is a shorter time period noticed for the synthesis when compared to the previous reports Biosynthesis of AgNPs was achieved by addition of culture supernatant with aqueous silver nitrate solution (1 mM). The reaction mixture exhibits change in colour from green to brown with a peak at 420 nm corresponding to the plasmon absorbance of AgNPs by UV-vis spectroscopy. The nanoparticles were characterised by X-ray diffraction (XRD), energy-dispersive X-ray analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy (SEM), Zetasizer and transmission electron microscopy (TEM). The XRD spectrum exhibited 2θ values corresponding to the silver nanocrystals. TEM and SEM micrographs revealed the extracellular formation of polydispersed elongated nanoparticles with an average size of 27.5 nm. Synthesised nanoparticles showed antibacterial property against both gram-positive and gram-negative microorganisms, but more effective towards gram-negative.

  8. 77 FR 75169 - Silver Nanoparticles (AgNPs); Information and Comment Request

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-19

    ... responses, and (3) histopathology changes in the kidney and especially in the liver, in which bile duct... to the liver . Studies also indicate that AgNPs can be transported and deposited in major organs and... histopathological effects to the liver in exposed Sprague-Dawley and F344 rats [Sung et al. 2009; Kim et al....

  9. Metabolic responses of the growing Daphnia similis to chronic AgNPs exposure as revealed by GC-Q-TOF/MS and LC-Q-TOF/MS.

    PubMed

    Zhang, Bo; Zhang, Hui; Du, Chunlei; Ng, Qin Xiang; Hu, Chaoyang; He, Yiliang; Ong, Choon Nam

    2017-05-01

    Silver nanoparticles (AgNPs) are one of the most widely used nanomaterials. Their fast-growing utilization has increased the occurrence of AgNPs in the environment, posing potential health and ecological risks. In this study, we conducted chronic toxicity tests and investigated the metabolic changes of the growing Daphna similis with exposure to 0, 0.02, and 1 ppb AgNPs, using non-targeted mass spectrometry-based metabolomics. To the best of our knowledge, this study is the first to report the baseline metabolite change of a common aquatic organism Daphnia crustacean through its life-cycle. The results show a dynamic kinetic pattern of the growing Daphnia's metabolome underwent a cycle from day 0 to day 21, with the level of metabolites gradually increasing from day 0 to day 13, before falling back to the baseline level of day 0 on day 21. As for the samples exposed to environmental concentrations of AgNPs, although without morphological or structural changes, numerous metabolite changes occurred abruptly during the first 10 days, and these changes reached steady state by day 13. The significant changes in certain metabolites, such as amino acids (serine, threonine and tyrosine), sugars (d-allose) and fatty acids (arachidonic acid) revealed new insights into how these metabolites in Daphnia respond to chronic AgNPs stress. These findings highlight the capability of metabolomics to discover early metabolic responses to environmental silver nanoparticles.

  10. Negligible particle-specific toxicity mechanism of silver nanoparticles: the role of Ag+ ion release in the cytosol.

    PubMed

    De Matteis, Valeria; Malvindi, Maria Ada; Galeone, Antonio; Brunetti, Virgilio; De Luca, Elisa; Kote, Sachin; Kshirsagar, Prakash; Sabella, Stefania; Bardi, Giuseppe; Pompa, Pier Paolo

    2015-04-01

    Toxicity of silver nanoparticles (AgNPs) is supported by many observations in literature, but no mechanism details have been proved yet. Here we confirm and quantify the toxic potential of fully characterized AgNPs in HeLa and A549 cells. Notably, through a specific fluorescent probe, we demonstrate the intracellular release of Ag(+) ions in living cells after nanoparticle internalization, showing that in-situ particle degradation is promoted by the acidic lysosomal environment. The activation of metallothioneins in response to AgNPs and the possibility to reverse the main toxic pathway by Ag(+) chelating agents demonstrate a cause/effect relationship between ions and cell death. We propose that endocytosed AgNPs are degraded in the lysosomes and the release of Ag(+) ions in the cytosol induces cell damages, while ions released in the cell culture medium play a negligible effect. These findings will be useful to develop safer-by-design nanoparticles and proper regulatory guidelines of AgNPs. From the clinical editor: The authors describe the toxic potential of silver nanoparticles (AgNP) in human cancer cell lines. Cell death following the application of AgNPs is dose-dependent, and it is mostly due to Ag+ ions. Further in vivo studies should be performed to gain a comprehensive picture of AgNP-toxicity in mammals.

  11. 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

    2016-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  13. Surface modification of cotton fabrics for antibacterial application by coating with AgNPs-alginate composite.

    PubMed

    Zahran, M K; Ahmed, Hanan B; El-Rafie, M H

    2014-08-08

    In recent years nano-sized particles have been focused on bacteriostasis. We investigated antimicrobial activities by applying AgNPs-alginate composite on cotton fabric, using a simple one-step rapid synthetic route by reduction of silver nitrate using alkali hydrolyzed alginate solution which acts as both reducing and capping agent. FTIR spectra, color coordinates, silver content, silver release percent and SEM images of treated fabric samples confirmed the successful physical deposition of AgNPs-alginate composite on the fabric. The treated fabrics demonstrated an excellent antibacterial activity against the tested bacteria, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. A slight decrease in the antibacterial feature of the cotton fabrics was observed after successive washings. However, an efficient antibacterial activity still remained on the fabrics.

  14. Polymers effects on synthesis of AuNPs, and Au/Ag nanoalloys: indirectly generated AuNPs and versatile sensing applications including anti-leukemic agent.

    PubMed

    Jahan, Shanaz; Mansoor, Farrukh; Kanwal, Shamsa

    2014-03-15

    Polymers either serve as shielding or capping agents to restrict the nanoparticle size. This study demonstrates the polymer depositions and their effects in synthesis and sharp stabilization of gold nanoparticles (AuNPs) and to develop gold/silver nanoalloys (Au/Ag nanoalloys). Effects of different polymers are tested to justify their role in synthesis and stability of phloroglucinol (PG) coated AuNPs and Au/Ag nanoalloys. Cationic and anionic i.e. [Polydiallyldimethylammonium](+) (PDDA), [Polyethyleneimine](+) (PEI), [Polystyrene sulfonate](2-) (PSS) and neutral polymer Polychlorotriflouroethylene (PCTFE) produce praiseworthy stable AuNPs and Au/Ag nanoalloy. To prove polymer effects characterization protocols including UV-vis, Fluorescence (PL), IR and AFM imaging are performed to fully investigate the mechanism and size characteristics of these nanoparticles/nanoalloys. In this study sharp size controlling/sheilding effects were observed particularly with cationic polymers simply through the favorable electrostatic interactions with the terminal ends of PG Potent/significant detection of doxorubicin (DOX, an antileukemic agent) via fluorescence resonance energy transfer (FRET) between PEI shielded AuNPs (AuNPEI) and DOX was achieved upto 10 pM level, while PDDA protected AuNPs facilitated the detection of ascorbic acid based on fluorescence enhancement effects in wide range (10-200 nM) and with detection limit of 200 pM. Similarly sensing performance of PEI stabilized Au/Ag nanoalloys on addition of halides (Cl(-), Br(-), I(-)) is evaluated through red shifted SPR along with continuous increase in absorbance and also through AFM. Moreover the addition of halide ions also helped the regeneration of AuNPs by taking away silver from the Au/Ag nanoalloys enabling their detections upto subnanomolar levels.

  15. Enhanced conductivity of rGO/Ag NPs composites for electrochemical immunoassay of prostate-specific antigen.

    PubMed

    Han, Lu; Liu, Cheng-Mei; Dong, Shi-Lei; Du, Cai-Xia; Zhang, Xiao-Yong; Li, Lu-Hai; Wei, Yen

    2017-01-15

    Electrode materials play a vital role in the development of electrochemical immunosensors (EIs), particularly of label-free EIs. In this study, composites containing reduced graphene oxide with silver nanoparticles (rGO/Ag NPs) were synthesized using binary reductants, i.e. hydrazine hydrate and sodium citrate. Due to the fact that graphene oxide (GO) was fully restored to rGO, and rGO stacking was effectively inhibited by insertion of small Ag NPs between the graphene sheets, the electrical conductivity of rGO/Ag NPs composites was significantly improved compared to rGO alone, with an enhancement factor of 346% at 40wt% of rGO. Moreover, the conducting path between rGO and Ag NPs formed because the structural defects in rGO were effectively repaired by decoration with Ag NPs. Subsequently, based on a screen-printed three-electrode system, a label-free EI for detecting prostate-specific antigen (PSA) was constructed using rGO/Ag NPs composites as a support material. The fabricated EIs demonstrated a wide linear response range (1.0-1000ng/ml), low detection limit (0.01ng/ml) and excellent specificity, reproducibility and stability. Thus, the proposed EIs based on rGO/Ag NPs composites can be easily extended for the ultrasensitive detection of different protein biomarkers.

  16. In situ assembly of well-dispersed Ag nanoparticles (AgNPs) on electrospun carbon nanofibers (CNFs) for catalytic reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Zhang, Peng; Shao, Changlu; Zhang, Zhenyi; Zhang, Mingyi; Mu, Jingbo; Guo, Zengcai; Liu, Yichun

    2011-08-01

    Carbon nanofibers/silver nanoparticles (CNFs/AgNPs) composite nanofibers were fabricated by two steps consisting of the preparation of the CNFs by electrospinning and the hydrothermal growth of the AgNPs on the CNFs. The as-prepared nanofibers were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, resonant Raman spectra, thermal gravimetric and differential thermal analysis, and X-ray photoelectron spectroscopy, respectively. The results indicated that not only were AgNPs (25-50 nm) successfully grown on the CNFs but also the AgNPs were distributed without aggregation on the CNFs. Further more, by adjusting the parameters in hydrothermal processing, the content of silver supported on the CNFs could be easily controlled. The catalytic activities of the CNFs/AgNPs composite nanofibers to the reduction of 4-nitrophenol (4-NP) with NaBH4 were tracked by UV-visible spectroscopy. It was suggested that the CNFs/AgNPs composite nanofibers exhibited high catalytic activity in the reduction of 4-NP, which might be attributed to the high surface areas of AgNPs and synergistic effect on delivery of electrons between CNFs and AgNPs. And, the catalytic efficiency was enhanced with the increasing of the content of silver on the CNFs/AgNPs composite nanofibers. Notably, the CNFs/AgNPs composite nanofibers could be easily recycled due to their one-dimensional nanostructural property.Carbon nanofibers/silver nanoparticles (CNFs/AgNPs) composite nanofibers were fabricated by two steps consisting of the preparation of the CNFs by electrospinning and the hydrothermal growth of the AgNPs on the CNFs. The as-prepared nanofibers were characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, X-ray diffraction, resonant Raman spectra, thermal gravimetric and differential thermal analysis, and X-ray photoelectron spectroscopy, respectively. The results

  17. Enhanced 1.53 μm band fluorescence in Er3+/Ce3+ codoped tellurite glasses containing Ag NPs

    NASA Astrophysics Data System (ADS)

    Wu, Libo; Huang, Bo; Yang, Fengjing; Qi, Yawei; Peng, Shengxi; Zhou, Yaxun; Li, Jun

    2015-05-01

    The silver nanoparticles (Ag NPs) was introduced into Er3+/Ce3+ codoped tellurite glasses with composition of TeO2-ZnO-La2O3 and the effects of Ag NPs on the 1.53 μm band spectroscopic properties of Er3+ ions, structural nature and thermal stability of glass hosts were investigated. The absorption spectra, upconversion emission spectra, 1.53 μm band fluorescence spectra together with the X-ray diffraction (XRD) patterns, differential scanning calorimeter (DSC) curves and transmission electron microscopy (TEM) image were measured. It was found that the near-spherical shape Ag NPs with average diameter of about 19 nm dispersed uniformly in the glass matrix, and the Er3+/Ce3+ codoped tellurite glasses containing Ag NPs exhibited an obvious enhancement in the 1.53 μm band fluorescence, which is attributed to the intensified local electric field induced by Ag NPs and the possible energy transfer from Ag NPs to Er3+ ions. The enhanced effect of Ag NPs on the 1.53 μm band fluorescence was elucidated by the obtained large Judd-Ofelt intensity parameter Ω6 and the calculated quantum efficiency of Er3+:4I13/2 level. In addition, the thermal stability of prepared glass samples increased with the introduction of Ag NPs and the amorphous structural nature was demonstrated by the measured XRD patterns with no sharp diffraction peak. The present results indicate that the prepared Er3+/Ce3+ codoped tellurite glass with Ag NPs has good prospect as a gain medium applied for 1.53 μm band Er3+-doped fiber amplifiers (EDFAs).

  18. Facile biosynthesis of Ag-NPs using Otostegia limbata plant extract: Physical characterization and auspicious biological activities

    NASA Astrophysics Data System (ADS)

    Kausar, Rizwan; Shaheen, Muhammad Ashraf; Maqbool, Qaisar; Naz, Sania; Nazar, Mudassar; Abbas, Fazal; Hussain, Talib; Younas, Umer; Shams, Muhammad Fahad

    2016-09-01

    Silver nanoparticles (Ag-NPs) synthesized through reduction by Otostegia limbata green extract are, hereby, reported for the first time. It is very interesting to observe that in this case, O. limbata plant extract acts as a strong chelating agent in Ag-NPs formation through AgNO3. Scanning electron microscope (SEM) studies expose that Ag-NPs formation is highly homogenous and spherical with mean particle size of 32 ±0.8 nm. A typical Ag absorption peak has been observed at 419 nm by ultra violet (UV)-visible spectroscopy which have endorsed the successful formation of single phase Ag-NPs. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) examination further validates the crystalline pure phase structure of Ag-NPs. Promising results have been recorded against protein kinase inhibition assay and antibacterial assay having prominent pathogenic strains. Our present study explores that biosynthesized eco-friendly Ag-NPs have great potential, in the future, for anticancer drug development with wide range pharmaceutical applications.

  19. Synthesis and optical properties study of nanocomposites based on AuNPs and AgNPs obtained by laser ablation in liquid monomer

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    In this work, Ag and Au nanoparticles (AgNPs and AuNPs) stable colloid solution were prepared by laser ablation of chemically pure silver rod and gold film in liquid monomer isodecyl acrylate (IDA). Sizes of obtained nanoparticles were determined by scanning electron microscope and vary from 30 to 130 nm. Nanocomposites films were prepared from obtained stable colloid solution by photocuring. To prepare solid film based on aliphatic polymer IDA long molecules cross-linking, 1,6-Hexandiol diacrylate was used. Obtained films were transparent, homogenous and colored in brown for AgNPs and purple for AuNPs-filled nanocomposites. Prepared nanomaterials exhibit strong third-order nonlinear optical responses under CW laser irradiation at 532 nm, which was estimated by using z-scan technique performed with open and close aperture. The real and imaginary parts of 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), for samples negative nonlinear refractive index was obtained, which corresponds to self-defocusing effect.

  20. 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.

  1. Toxicity of citrate-capped AuNPs: an in vitro and in vivo assessment

    NASA Astrophysics Data System (ADS)

    Sabella, Stefania; Brunetti, Virgilio; Vecchio, Giuseppe; Galeone, Antonio; Maiorano, Gabriele; Cingolani, Roberto; Pompa, Pier Paolo

    2011-12-01

    In this study, we show that 15 nm citrate-capped AuNPs exert a remarkable toxicity in living systems. The assessment was performed by using well-characterized AuNPs, the combination of in vitro and in vivo models (namely two different cell lines and Drosophila melanogaster), exposure to low dosages of nanoparticles (in the sub-nanomolar concentration range), along with the application of several biological assays to monitor different aspects of the toxic effects, such as viability, genotoxicity, and molecular biomarkers.

  2. Antibacterial and antifouling activities of chitosan/TiO2/Ag NPs nanocomposite films against packaged drinking water bacterial isolates.

    PubMed

    Natarajan, Saravanan; Bhuvaneshwari, M; Lakshmi, D Shanthana; Mrudula, P; Chandrasekaran, N; Mukherjee, Amitava

    2016-10-01

    TiO2 and Ag NPs are widely used as antibacterial agents against many bacterial pathogens. Chitosan (polymer) itself acts as a strong antibacterial agent. Hence, chitosan/TiO2/Ag NPs incorporated nanocomposite film was prepared against packed drinking water bacterial strains. A concentration-dependent increase in the reduction of cell viability was observed in all the isolates under UV-C and dark exposure conditions. The bacteria consortium showed greater resistance against antibacterial effects of chitosan/TiO2/Ag nanocomposite as compared to single isolates. Glycocalyx test and mass assessment conclude the effective antibacterial activity by inhibiting bacterial adhesion on the film surface. The release of LDH and generation of ROS act as the predominant antibacterial mechanism induced by TiO2/Ag NPs. Surface characterization of chitosan/TiO2/Ag nanocomposite was studied by FTIR and XRD analyses and SEM analysis after interaction with the bacteria.

  3. Concentration-Dependent, Size-Independent Toxicity of Citrate Capped AuNPs in Drosophila melanogaster

    PubMed Central

    Brunetti, Virgilio; Maiorano, Gabriele; Sabella, Stefania; Cingolani, Roberto; Pompa, Pier Paolo

    2012-01-01

    The expected potential benefits promised by nanotechnology in various fields have led to a rapid increase of the presence of engineered nanomaterials in a high number of commercial goods. This is generating increasing questions about possible risks for human health and environment, due to the lack of an in-depth assessment of the physical/chemical factors responsible for their toxic effects. In this work, we evaluated the toxicity of monodisperse citrate-capped gold nanoparticles (AuNPs) of different sizes (5, 15, 40, and 80 nm) in the model organism Drosophila melanogaster, upon ingestion. To properly evaluate and distinguish the possible dose- and/or size-dependent toxicity of the AuNPs, we performed a thorough assessment of their biological effects, using two different dose-metrics. In the first approach, we kept constant the total surface area of the differently sized AuNPs (Total Exposed Surface area approach, TES), while, in the second approach, we used the same number concentration of the four different sizes of AuNPs (Total Number of Nanoparticles approach, TNN). We observed a significant AuNPs-induced toxicity in vivo, namely a strong reduction of Drosophila lifespan and fertility performance, presence of DNA fragmentation, as well as a significant modification in the expression levels of genes involved in stress responses, DNA damage recognition and apoptosis pathway. Interestingly, we found that, within the investigated experimental conditions, the toxic effects in the exposed organisms were directly related to the concentration of the AuNPs administered, irrespective of their size. PMID:22238688

  4. 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...

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. Plasmon-induced photodegradation of toxic pollutants with Ag-AgI/Al2O3 under visible-light irradiation.

    PubMed

    Hu, Chun; Peng, Tianwei; Hu, Xuexiang; Nie, Yulun; Zhou, Xuefeng; Qu, Jiuhui; He, Hong

    2010-01-20

    A plasmonic photocatalyst Ag-AgI supported on mesoporous alumina (Ag-AgI/Al(2)O(3)) was prepared by deposition-precipitation and photoreduction methods. The catalyst showed high and stable photocatalytic activity for the degradation and mineralization of toxic persistent organic pollutants, as demonstrated with 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and trichlorophenol (TCP) under visible light or simulated solar light irradiation. On the basis of electron spin resonance, cyclic voltammetry analyses under a variety of experimental conditions, two electron transfer processes were verified from the excited Ag NPs to AgI and from 2-CP to the Ag NPs, and the main active species of O(2)(*-) and excited h(+) on Ag NPs were involved in the photoreaction system of Ag-AgI/Al(2)O(3). A plasmon-induced photocatalytic mechanism was proposed. Accordingly, the plasmon-induced electron transfer processes elucidated the photostability of Ag-AgI/Al(2)O(3). This finding indicates that the high photosensitivity of noble metal NPs due to surface plasmon resonance could be applied toward the development of new plasmonic visible-light-sensitive photocatalysts and photovoltaic fuel cells.

  10. Aminated polyethersulfone-silver nanoparticles (AgNPs-APES) composite membranes with controlled silver ion release for antibacterial and water treatment applications.

    PubMed

    Haider, M Salman; Shao, Godlisten N; Imran, S M; Park, Sung Soo; Abbas, Nadir; Tahir, M Suleman; Hussain, Manwar; Bae, Wookeun; Kim, Hee Taik

    2016-05-01

    The present study reports the antibacterial disinfection properties of a series of silver nanoparticle (AgNP) immobilized membranes. Initially, polyethersulfone (PES) was functionalized through the introduction of amino groups to form aminated polyethersulfone (NH2-PES, APES). AgNPs were then coordinately immobilized on the surface of the APES composite membrane to form AgNPs-APES. The properties of the obtained membrane were examined by FT-IR, XPS, XRD, TGA, ICP-OES and SEM-EDAX analyses. These structural characterizations revealed that AgNPs ranging from 5 to 40 nm were immobilized on the surface of the polymer membrane. Antibacterial tests of the samples showed that the AgNPs-APES exhibited higher activity than the AgNPs-PES un-functionalized membrane. Generally, the AgNPs-APES 1 cm × 3 cm strip revealed a four times longer life than the un-functionalized AgNPs polymer membranes. The evaluation of the Ag(+) leaching properties of the obtained samples indicated that approximately 30% of the AgNPs could be retained, even after 12 days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25 days. The present study provides a systematic and novel approach to synthesize water treatment membranes with controlled and improved silver (Ag(+)) release to enhance the lifetime of the membranes.

  11. 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.

  12. 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.

    2017-01-01

    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.

  13. 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.

  14. Spectroscopic probe to contribution of physicochemical transformations in the toxicity of aged ZnO NPs to Chlorella vulgaris: new insight into the variation of toxicity of ZnO NPs under aging process.

    PubMed

    Zhang, Hong; Huang, Qing; Xu, An; Wu, Lijun

    2016-10-01

    Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly applied nanomaterials in nanotechnology-based industries and they may cause unexpected environmental and health risks with their physicochemical transformations in the environment. Currently, there is still a lack of the in-depth understanding of the toxicity of aged ZnO NPs to aquatic organisms, particularly demanding quantitative analysis of the physicochemical transformations to distinguish their contributions in the toxicity assessment. For this purpose, therefore, we initiated the study of the toxicity of aged ZnO NPs to the model aquatic microalga, i.e. Chlorella vulgaris, and with the aid of spectroscopic tools for characterization and quantification of the physicochemical transformations, we scrutinized the toxicity variations for ZnO NPs with different aging times. As a result, we found that the toxicity altered in an abnormal manner with the aging time, i.e. the toxicity of aged ZnO NPs for 30 days showed the higher toxicity to the green alga than the fresh ZnO NPs or the ZnO NPs aged for longer time (e.g. 120 and 210 days). Through spectroscopic tools such as XRD, FTIR and Raman spectroscopy, we made both the qualitative and quantitative assessments of the physicochemical changes of the ZnO NPs, and confirmed that in the early stage, the toxicity mainly stemmed from the release of zinc ions, but with longer aging time, the neoformation of the nanoparticles played the critical role, leading to the overall reduced toxicity due to the less toxic hydrozincite and zinc hydroxide in the transformed compounds.

  15. Studies on the impact of biosynthesized silver nanoparticles (AgNPs) in relation to malaria and filariasis vector control against Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae).

    PubMed

    Subarani, Selladurai; Sabhanayakam, Selvi; Kamaraj, Chinnaperumal

    2013-02-01

    . Energy-dispersive X-ray spectroscopy showed the complete chemical composition of the synthesized AgNPs. In larvicidal activity, the results showed that the maximum efficacy was observed in synthesized AgNPs against the fourth instar larvae of A. stephensi (LC(50) = 12.47 and 16.84 mg/mL and LC(90) = 36.33 and 68.62 mg/mL) on 48 and 72 h of exposure and against C. quinquefasciatus (LC(50) = 43.80 mg/mL and LC(90) = 120.54 mg/mL) on 72-h exposure, and aqueous extract showed 100 % mortality against A. stephensi and C. quinquefasciatus (LC(50) = 78.62 and 55.21 mg/mL and LC(90) = 184.85 and 112.72 mg/mL) on 72-h exposure at concentrations of 50 mg/mL, respectively. The AgNPs did not exhibit any noticeable toxicity on Poecilia reticulata after 24, 48, and 72 h of exposure. These results suggest that the synthesized AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi and C. quinquefasciatus. This method is considered as a new approach to control vectors. Therefore, this study provides the first report on the mosquito larvicidal activity of V. rosea synthesized AgNPs against vectors.

  16. Effects of reducibility of graphene oxide nanosheets on preparation of AgNPs/GO nanocomposites and their electrocatalytic performance

    NASA Astrophysics Data System (ADS)

    Dou, Yanpeng; Peng, Junjun; Li, Wei; Li, Ming; Liu, Huihong; Zhang, Hanmin

    2015-12-01

    Silver nanoparticles/graphene oxide (AgNPs/GO) nanocomposites were prepared in a solution of AgNO3 and GO. The GO serves not only as a reductant but also as a substrate to support the as-reduced silver nanoparticles. The reducibility of GO was investigated by analyzing the influence factors such as pH, duration, the reaction temperature, and the weight ratio of AgNO3 and GO in the AgNP/GO nanocomposite mixture, which were evaluated by the UV-vis absorption spectroscopy. The results demonstrated that Ag nanoparticles with an average diameter of 5-10 nm were uniformly dispersed on the surface of GO nanosheets under the optimum synthesis conditions of pH between 8 and 11, weight ratio of AgNO3 and GO between 55 % and 60 %, and at 80 °C for 6 h. Moreover, the obtained AgNPs/GO nanocomposites exhibit good electrocatalytic activity for the reduction of p-nitrophenol to 4-(hydroxyamino) phenol.

  17. Comparative toxicity of silver nanoparticles on oxidative stress and DNA damage in the nematode, Caenorhabditis elegans.

    PubMed

    Ahn, Jeong-Min; Eom, Hyun-Jeong; Yang, Xinyu; Meyer, Joel N; Choi, Jinhee

    2014-08-01

    This study examined the effects of polyvinylpyrrolidone (PVP) surface coating and size on the organismal and molecular toxicity of silver nanoparticles (AgNPs) on the nematode, Caenorhabditis elegans. The toxicity of bare AgNPs and 8 and 38 nm PVP-coated AgNPs (PVP8-AgNPs, PVP38-AgNPs) were compared. The toxicity of AgNO3 was also tested because ion dissolution and particle-specific effects are often important characteristics determining Ag nanotoxicity. Comparative toxicity across AgNO3 and the three different types of AgNPs was first evaluated using a C. elegans mortality test by a direct comparison of the LC50 values. Subsequently, mutant screening followed by oxidative stress, mitochondrial toxicity and DNA damage assays were carried out at equitoxic (LC10 and LC50) concentrations to further assess the toxicity mechanism of AgNO3 and AgNPs. AgNO3 and bare AgNPs had similar toxicities, whereas PVP coating reduced the toxicity of the AgNPs significantly. Of the PVP-AgNPs, the smaller NPs were more toxic. Different groups of mutants responded differently to AgNO3 and AgNPs, which indicates that their toxicity mechanism might be different. AgNO3 and bare AgNPs induced mitochondrial membrane damage. None of the silver materials tested caused detectable polymerase-inhibiting DNA lesions in either the nucleus or mitochondria as measured by a quantitative PCR assay, but AgNO3, bare AgNPs and PVP8-AgNPs induced oxidative DNA damage. These results show that coatings on the AgNPs surface and the particle size make a clear contribution to the toxicity of the AgNPs, and oxidative stress-related mitochondrial and DNA damage appear to be potential mechanisms of toxicity.

  18. Enhanced photocatalytic performance of sandwiched ZnO@Ag@Cu₂O nanorod films: the distinct role of Ag NPs in the visible light and UV region.

    PubMed

    Ren, Shoutian; Zhao, Guoliang; Wang, Yingying; Wang, Benyang; Wang, Qiang

    2015-03-27

    Sandwiched ZnO@Ag@Cu2O nanorod films were synthesized by successive electrodeposition, magnetron sputtering and the second electrodeposition. The as-synthesized composites were characterized by x-ray diffraction patterns, field emission scanning electron microscopy, low- and high-resolution transmission electron microscopy and a UV-vis spectrophotometer. Their photocatalytic performance was estimated by the degradation of a methyl orange solution under UV or visible-light irradiation, respectively. In the visible region, due to localized surface plasmon resonance absorption of Ag NPs, ZnO@Ag@Cu2O showed a significantly enhanced photocatalytic performance. The enhancement factor of Ag NPs on the catalytic performance of ZnO@Ag@Cu2O was estimated as a function of the Cu2O deposition time, and the corresponding enhancement mechanism was also evaluated by the monochromatic photocatalytic experiment and discrete dipole approximation simulation. In the UV region, due to the formation of a Schottky junction (e.g. Ag/ZnO, Ag/Cu2O), a limited enhanced photocatalytic performance was also realized for ZnO@Ag@Cu2O photocatalysts.

  19. Decorating CdTe QD-Embedded Mesoporous Silica Nanospheres with Ag NPs to Prevent Bacteria Invasion for Enhanced Anticounterfeit Applications.

    PubMed

    Gao, Yangyang; Dong, Qigeqi; Lan, Shi; Cai, Qian; Simalou, Oudjaniyobi; Zhang, Shiqi; Gao, Ge; Chokto, Harnoode; Dong, Alideertu

    2015-05-13

    Quantum dots (QDs) as potent candidates possess advantageous superiority in fluorescence imaging applications, but they are susceptible to the biological circumstances (e.g., bacterial environment), leading to fluorescence quenching or lose of fluorescent properties. In this work, CdTe QDs were embedded into mesoporous silica nanospheres (m-SiO2 NSs) for preventing QD agglomeration, and then CdTe QD-embedded m-SiO2 NSs (m-SiO2/CdTe NSs) were modified with Ag nanoparticles (Ag NPs) to prevent bacteria invasion for enhanced anticounterfeit applications. The m-SiO2 NSs, which serve as intermediate layers to combine CdTe QDs with Ag NPs, help us establish a highly fluorescent and long-term antibacterial system (i.e., m-SiO2/CdTe/Ag NSs). More importantly, CdTe QD-embedded m-SiO2 NSs showed fluorescence quenching when they encounter bacteria, which was avoided by attaching Ag NPs outside. Ag NPs are superior to CdTe QDs for preventing bacteria invasion because of the structure (well-dispersed Ag NPs), size (small diameter), and surface charge (positive zeta potentials) of Ag NPs. The plausible antibacterial mechanisms of m-SiO2/CdTe/Ag NSs toward both Gram-positive and Gram-negative bacteria were established. As for potential applications, m-SiO2/CdTe/Ag NSs were developed as fluorescent anticounterfeiting ink for enhanced imaging applications.

  20. Green synthesis, characterisation and biological evaluation of AgNPs using Agave americana, Mentha spicata and Mangifera indica aqueous leaves extract.

    PubMed

    Ahmad, Bashir; Shireen, Farah; Bashir, Shumaila; Khan, Ibrar; Azam, Sadiq

    2016-10-01

    The current study was performed to synthesize stable, eco-friendly and bio-compatible silver nano-particles (AgNPs) of Agave americana, Mentha spicata and Mangifera indica leaves and to screen them for biological activities. The ultraviolet-visible spectroscopic analysis revealed that λ-max for AgNPs range from 350-500 nm. All AgNPs possessed polycrystalline structure as notified as intense graphical peaks in complete spectrum of 20 values ranging from 10-80° in X-ray diffraction measurements and supported by scanning electron microscopy data. The size of the nano-particles was confirmed by transmission electron microscopy (30-150 nm). Mass loss at variable temperatures was evaluated by simultaneous thermogravimetric and differential thermal analysis revealed reduction in mass and activity of compounds was notified by temperature increase from 200 to 800 °C, thus concluding it as thermally sensitive compounds. A. americana AgNPs showed significant (96%) activity against Methicillin resistant Staphylococcus aureus, Escherichia coli (95%) and Fusarium oxysporum (89%). Good antioxidant activity was shown by M. spicata AgNPs at 300 µl (79%). M. indica AgNPs showed significant phytotoxic activity (88%) at highest concentration. No haemagglutination reaction was observed for the test samples. The above results revealed that AgNPs synthesized from selected plant species possesses significant antimicrobial and phytotoxic effect.

  1. 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%.

  2. Chronic ZnO-NPs exposure at environmentally relevant concentrations results in metabolic and locomotive toxicities in Caenorhabditis elegans.

    PubMed

    Huang, Chi-Wei; Li, Shang-Wei; Hsiu-Chuan Liao, Vivian

    2017-01-01

    ZnO nanoparticles (ZnO-NPs) are emerging contaminants that raise the concerns of potential risk in the aquatic environment. It has been estimated that the environmental ZnO-NPs concentration is 76 μg/l in the aquatic environment. Our aim was to determine the aquatic toxicity of ZnO-NPs with chronic exposure at environmentally relevant concentrations using the nematode Caenorhabditis elegans. Two simulated environmentally relevant mediums-moderately hard reconstituted water (EPA water) and simulated soil pore water (SSPW)-were used to represent surface water and pore water in sediment, respectively. The results showed that the ZnO-NPs in EPA water has a much smaller hydrodynamic diameter than that in SSPW. Although the ionic release of Zn ions increased time-dependently in both mediums, the Zn ions concentrations in EPA water increased two-fold more than that in SSPW at 48 h and 72 h. The ZnO-NPs did not induce growth defects or decrease head thrashes in C. elegans in either media. However, chronic exposure to ZnO-NPs caused a significant reduction in C. elegans body bends in EPA water even with a relatively low concentration (0.05 μg/l); similar results were not observed in SSPW. Moreover, at the same concentrations (50 and 500 μg/l), body bends in C. elegans were reduced more severely in ZnO-NPs than in ZnCl2 in EPA water. The ATP levels were consistently and significantly decreased, and ROS was induced after ZnO-NPs exposure (50 and 500 μg/l) in EPA water. Our results provide evidences that chronic exposure to ZnO-NPs under environmentally relevant concentrations causes metabolic and locomotive toxicities implicating the potential ecotoxicity of ZnO-NPs at low concentrations in aquatic environments.

  3. 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.

  4. C. elegans-on-a-chip for in situ and in vivo Ag nanoparticles’ uptake and toxicity assay

    PubMed Central

    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. PMID:28067319

  5. 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.

  6. Biofabrication of Ag nanoparticles using Sterculia foetida L. seed extract and their toxic potential against mosquito vectors and HeLa cancer cells.

    PubMed

    Rajasekharreddy, Pala; Rani, Pathipati Usha

    2014-06-01

    A one-step and eco-friendly process for the synthesis of silver-(protein-lipid) nanoparticles (Ag-PL NPs) (core-shell) has been developed using the seed extract from wild Indian Almond tree, Sterculia foetida (L.) (Sterculiaceae). The reaction temperature played a major role in controlling the size and shell formation of NPs. The amount of NPs synthesized and qualitative characterization was done by UV-vis spectroscopy and transmission electron microscopy (TEM), respectively. TEM studies exhibited controlled dispersity of spherical shaped NPs with an average size of 6.9±0.2nm. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) revealed 'fcc' phase and crystallinity of the particles. X-ray photoelectron spectroscopy (XPS) was used to identify the protein-lipid (PL) bilayer that appears as a shell around the Ag core particles. The thermal stability of the Ag-PL NPs was examined using thermogravimetric analysis (TGA). Further analysis was carried out by using Fourier transform infrared spectroscopy (FTIR), where the spectra provided evidence for the presence of proteins and lipid moieties ((2n-octylcycloprop-1-enyl)-octanoic acid (I)), and their role in synthesis and stabilization of Ag NPs. This is the first report of plant seed assisted synthesis of PL conjugated Ag NPs. These formed Ag-PL NPs showed potential mosquito larvicidal activity against Aedes aegypti (L.), Anopheles stephensi Liston and Culex quinquefasciatus Say. These Ag-PL NPs can also act as promising agents in cancer therapy. They exhibited anti-proliferative activity against HeLa cancer cell lines and a promising toxicity was observed in a dose dependent manner. Toxicity studies were further supported by the cellular DNA fragmentation in the Ag-PL NPs treated HeLa cells.

  7. A highly sensitive hydrogen peroxide sensor based on (Ag-Au NPs)/poly[o-phenylenediamine] modified glassy carbon electrode.

    PubMed

    Shamsipur, Mojtaba; Karimi, Ziba; Amouzadeh Tabrizi, Mahmoud

    2015-11-01

    Herein, the poly(o-phenylenediamine) decorated with gold-silver nanoparticle (Ag-Au NPs) nanocomposite modified glassy carbon was used for the determination of hydrogen peroxide. Electrochemical experiments indicated that the proposed sensor possesses an excellent sensitivity toward the reduction of hydrogen peroxide. The resulting sensor exhibited a good response to hydrogen peroxide over linear range from 0.2 to 60.0μM with a limit of detection of 0.08μM, good reproducibility, long-term stability and negligible interference from ascorbic acid, uric acid and dopamine. The proposed sensor was successfully applied to the determination of hydrogen peroxide in human serum sample.

  8. Composite structure of SiO2@AgNPs@p-SiNWs for enhanced broadband optical antireflection.

    PubMed

    Lu, Ren; Wang, Yewu; Gu, Lin; Wang, Wei; Fang, Yanjun; Sha, Jian

    2013-07-29

    The composite structure of SiO(2)@AgNPs@p-SiNWs based on silicon nanowires (SiNWs) produced by metal-assisted chemical etching (MaCE) method has been designed to realize the significant reflection suppression over a broad wavelength range (300 - 2500 nm). Especially, the reflectivity of the structure even below 0.3% at a wide range of 620 - 1950 nm can be achieved. It also has been demonstrated that SiO(2) capers play a dominant role in the significant reflection suppression of the composite structure.

  9. 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

  10. Selective colorimetric sensors based on the monitoring of an unmodified silver nanoparticles (AgNPs) reduction for a simple and rapid determination of mercury

    NASA Astrophysics Data System (ADS)

    Jarujamrus, Purim; Amatatongchai, Maliwan; Thima, Araya; Khongrangdee, Thatsanee; Mongkontong, Chakrit

    2015-05-01

    In this work, selective colorimetric sensors for simple and rapid detection of Hg(II) ions based on the monitoring of an unmodified silver nanoparticles (AgNPs) reduction were developed. The average diameter of synthesized AgNPs was 8.3 ± 1.4 nm which was characterized by transmission electron microscopy (TEM). The abrupt change in absorbance of the unmodified AgNPs was observed which progressively decreased and slightly shifted to the blue wavelength as the concentration of Hg(II) increased, indicating the oxidation of Ag(0) to Ag(I) occurred. It appears that the AgNPs were oxidized by Hg(II), resulting in disintegration of the AgNPs into smaller particles as well as mediating the reduction of Hg(II) to Hg(0) adsorbed onto the surface of AgNPs. The adsorption of Hg(0) resulted in the lack of sufficient charges on AgNPs surfaces due to the decrease in the surface coverage of negatively charged citrate molecules, which then leaded to enlargement of AgNPs. The calibration curve of this technique was demonstrated from 0.5 to 7 ppm (r2 = 0.995), the limit of detection (LOD) was 0.06 ppm (SDblank/slope of calibration curve) with the precision (RSD, n = 4) of 3.24-4.53. Interestingly, the results show a significant enhance in the Hg(II) analytical sensitivity when Cu(II) is doped onto the unmodified AgNPs, which improves the quantitative detection limit to 0.008 ppm. In addition, greater selectivity toward Hg(II) compared with the other metal ions tested was observed. Furthermore, the percentage recoveries of spiked drinking water, tap water and SRM1641d (mercury in water) were in acceptable range with a good precision (RSD) which were in agreement with the values obtained from graphite furnace atomic absorption spectrometer (GFAAS). The technique proposed in this study provides a rapid, simple, sensitive and selective detection method for Hg(II) in water samples.

  11. Selective colorimetric sensors based on the monitoring of an unmodified silver nanoparticles (AgNPs) reduction for a simple and rapid determination of mercury.

    PubMed

    Jarujamrus, Purim; Amatatongchai, Maliwan; Thima, Araya; Khongrangdee, Thatsanee; Mongkontong, Chakrit

    2015-05-05

    In this work, selective colorimetric sensors for simple and rapid detection of Hg(II) ions based on the monitoring of an unmodified silver nanoparticles (AgNPs) reduction were developed. The average diameter of synthesized AgNPs was 8.3±1.4nm which was characterized by transmission electron microscopy (TEM). The abrupt change in absorbance of the unmodified AgNPs was observed which progressively decreased and slightly shifted to the blue wavelength as the concentration of Hg(II) increased, indicating the oxidation of Ag(0) to Ag(I) occurred. It appears that the AgNPs were oxidized by Hg(II), resulting in disintegration of the AgNPs into smaller particles as well as mediating the reduction of Hg(II) to Hg(0) adsorbed onto the surface of AgNPs. The adsorption of Hg(0) resulted in the lack of sufficient charges on AgNPs surfaces due to the decrease in the surface coverage of negatively charged citrate molecules, which then leaded to enlargement of AgNPs. The calibration curve of this technique was demonstrated from 0.5 to 7ppm (r(2)=0.995), the limit of detection (LOD) was 0.06ppm (SDblank/slope of calibration curve) with the precision (RSD, n=4) of 3.24-4.53. Interestingly, the results show a significant enhance in the Hg(II) analytical sensitivity when Cu(II) is doped onto the unmodified AgNPs, which improves the quantitative detection limit to 0.008ppm. In addition, greater selectivity toward Hg(II) compared with the other metal ions tested was observed. Furthermore, the percentage recoveries of spiked drinking water, tap water and SRM1641d (mercury in water) were in acceptable range with a good precision (RSD) which were in agreement with the values obtained from graphite furnace atomic absorption spectrometer (GFAAS). The technique proposed in this study provides a rapid, simple, sensitive and selective detection method for Hg(II) in water samples.

  12. Improved nonlinear optical and optical limiting properties in non-covalent functionalized reduced graphene oxide/silver nanoparticle (NF-RGO/Ag-NPs) hybrid

    NASA Astrophysics Data System (ADS)

    Sakho, El hadji Mamour; Oluwafemi, Oluwatobi S.; Sreekanth, P.; Philip, Reji; Thomas, Sabu; Kalarikkal, Nandakumar

    2016-08-01

    Nonlinear optical (NLO) response under near infrared (800 nm) and visible (532 nm) laser excitations, of 100 fs (fs) and 5 ns (ns) pulse durations respectively, of reduced graphene oxide (RGO), non-covalent functionalized reduced graphene oxide (NF-RGO) and NF-RGO decorated with various concentration of silver nanoparticles (NF-RGO/Ag-NPs) have been investigated using the Open-aperture Z-Scan technique. For both femtosecond and nanosecond laser excitations, the studied graphene-based materials exhibit good nonlinear optical power limiting properties (OL), with NF-RGO/Ag-NPs sample prepared with 0.1 M AgNO3 showing the best nonlinear optical properties. For the ns regime, the optical limiting threshold decreased from 8.3 J/cm2 in NF-RGO to 4.3 J/cm2 in NF-RGO/Ag-NPs, while at fs regime, the nonlinear absorption coefficient (β) was found to increase with decrease in concentration of Ag-NPs in the hybrid. Two-photon absorption (2 PA) in combination with saturable absorption (SA) in femtosecond regime, and reverse saturable absorption (RSA) along with saturable absorption (SA) in the nanosecond regime, are responsible for the observed nonlinear optical absorption (NLA) behavior in these materials. These findings show that the as-synthesized NF-RGO/Ag-NPs hybrid is a relatively better material for nonlinear optical limiting applications.

  13. Determination of TiO2 and AgTiO2 Nanoparticles in Artemia salina: Toxicity, Morphological Changes, Uptake and Depuration.

    PubMed

    Ozkan, Yesim; Altinok, Ilhan; Ilhan, Hasan; Sokmen, Munevver

    2016-01-01

    In this study, aquatic stability and toxic effects of TiO2 and AgTiO2 nanoparticles (NPs) were investigated on Artemia salina nauplii. AgTiO2 was found to be more toxic to nauplii compared to TiO2. The mortality rate in nauplii increased significantly with increasing concentrations and duration of exposure. TiO2 eliminations ranged between 27.8% and 96.5% at 50 and 1 mg/L TiO2 exposed to nauplii, respectively. Accumulation and elimination of Ag in AgTiO2 exposed nauplii were similar except at 1 mg/L AgTiO2. When NPs were mixed with water, the hydrodynamic dimensions of NPs significantly increased because of aggregation in saltwater but NP size decreased over time. NPs-exposed nauplii showed changes in eye formation, enlargement of the intestine, malformations in the outer shell and antennae loss were also observed. Since accumulation and toxicity of AgTiO2 NPs was higher than TiO2 alone, inevitably release of AgTiO2 into aqueous environments can cause ecological risks.

  14. Influences of Ag-NPs doping chitosan/calcium silicate nanocomposites for optical and antibacterial activity.

    PubMed

    El-Nahrawy, Amany M; Ali, Ahmed I; Abou Hammad, Ali B; Youssef, Ahmed M

    2016-12-01

    Chitosan (CS)/calcium silicate nanocomposites pure and doped with Ag ions (1, 2mol%) were prepared via sol-gel method. The prepared CS/calcium silicate nanocomposites were investigated through X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The XRD results, indicating that after increasing the Ag ions in the CS/calcium silicate nanocomposite the crystallinity degree increased regularly in the prepared nanocomposites accompanying to the continuously rearrangement in the internal structure of nanocomposite under the effect of inorganic nanoparticles. Correspondingly, the optical properties of the prepared nanocomposites films were measured using UV/vis spectroscopy. The reflectance increased while the energy band gap decreased from 3.96eV to 2.43eV with Ag-ions concentration. More over the transition type changed from direct into indirect by adding Ag-ions, indicate that new band between valence and conduction band were formed. In addition, the optical parameters showed an increase in refractive indices and decrease in the surface and volume energies losses with increasing Ag-ions. Correspondingly, the prepared nanocomposites exhibited good antibacterial activity against gram positive (Staphylococcus aureus), gram negative (Pseudomonas aeruginosa) bacteria and fungi (Candidia albicans). The results suggested that the prepared CS/calcium silicate nanocomposites can be a promised candidate for optical sensors applications and smart packaging materials.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Soleyman, R.; Pourjavadi, A.; Masoud, N.; Varamesh, A.

    2014-04-01

    In the current study, γ-Fe2O3/SiO2/PCA/Ag-NPs hybrid nanomaterials were successfully synthesized and characterized. At first, prepared γ-Fe2O3 core nanoparticles were modified by SiO2 layer. Then they were covered by poly citric acid (PCA) via melting esterification method as well. PCA shell acts as an effective linker, and provides vacancies for conveying drugs. Moreover, this shell as an effective capping agent directs synthesis of silver nanoparticles (Ag-NPs) via in situ photo-reduction of silver ions by sunlight-UV irradiation. This system has several benefits as a suitable cancer therapy nanomaterial. Magnetic nanoparticles (MNPs) can guide Ag-NPs and drugs to cancer cells and then Ag-NPs can affect those cells via Ag-NPs anti-angiogenesis effect. Size and structure of the prepared magnetic hybrid nanomaterials were characterized using FTIR and UV-Vis spectra, AFM and TEM pictures and XRD data.

  17. Silver nanoparticle toxicity in sea urchin Paracentrotus lividus.

    PubMed

    Siller, Lidija; Lemloh, Marie-Louise; Piticharoenphun, Sunthon; Mendis, Budhika G; Horrocks, Benjamin R; Brümmer, Franz; Medaković, Davorin

    2013-07-01

    Silver nanoparticles (AgNPS) are an important model system for studying potential environmental risks posed by the use of nanomaterials. So far there is no consensus as to whether toxicity is due to AgNPs themselves or Ag(+) ions leaching from their surfaces. In sea urchin Paracentrotus lividus, AgNPs cause dose dependent developmental defects such as delayed development, bodily asymmetry and shortened or irregular arms, as well as behavioural changes, particularly in swimming patterns, at concentration ∼0.3 mg/L AgNPs. It has been observed that AgNPs are more toxic than their equivalent Ag(+) ion dose.

  18. Silver nanoparticles: in vivo toxicity in zebrafish embryos and a comparison to silver nitrate

    NASA Astrophysics Data System (ADS)

    Mosselhy, Dina A.; He, Wei; Li, Dan; Meng, Yaping; Feng, Qingling

    2016-08-01

    The wide antimicrobial administration of silver nanoparticles (AgNPs) has raised the risks associated with their exposure. However, there is lack of robust toxicological data for the applied AgNPs to be in line with their wide antimicrobial applications. This study therefore set out to assess the in vivo toxicity of two different sizes of AgNPs using zebrafish embryos ( Danio rerio) as a brilliant in vivo model. The pivotal role of size of AgNPs in the toxicity was highlighted, wherein the smaller AgNPs (Ag-9 nm) exhibited more embryo toxicities than the larger particles (Ag-30 nm). Much uncertainty still exists about whether the cause of in vivo toxicity of AgNPs is the physicochemical properties of AgNPs or the released silver ions (Ag+). Therefore, another purpose of this study is to compare the toxicity of AgNPs with silver nitrate (AgNO3) in terms of mortality, hatchability and cardiac rates, and a series of phenotypic endpoints of zebrafish embryos. Collectively, the present results point towards the remarkable size-dependent toxicity of AgNPs. Wherein, the smaller AgNPs (9 ± 2 nm) induce increased mortality rates and decreased hatchability rates than the larger particles (30 ± 5 nm) in a dose-dependent manner. Besides, AgNPs and AgNO3 induce holistic different toxic mortality and hatchability rates. We have also found striking discrepancies in the phenotypic defects that were induced by AgNPs and AgNO3. The significant phenotypic defect induced by AgNPs is the axial deformity, while it is the deposition of Ag+ on the embryonic chorion for AgNO3. Therefore, it is proposed that AgNPs and AgNO3 induce different in vivo toxicities.

  19. Application of cow milk-derived carbon dots/Ag NPs composite as the antibacterial agent

    NASA Astrophysics Data System (ADS)

    Han, Shuai; Zhang, He; Xie, Yujie; Liu, Liangliang; Shan, Changfu; Li, Xiangkai; Liu, Weisheng; Tang, Yu

    2015-02-01

    Cow milk-derived carbon dots (CMCDs) were prepared by hydrothermal treatment of cow milk, and the as-prepared CMCDs were further extracted by ethyl acetate to obtain amphiphilic CMCDs (ACMCDs). Using the ACMCDs both as a reducing agent and a template, the ACMCDs-supported silver nanoparticles (ACMCD-Ag nanocomposites) were prepared, which showed good biocidal effect on both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterias. After that, a novel ACMCD-Ag/polymethylmethacrylate nanocomposite antibacterial film was fabricated by solvent casting method. Due to the excellent antibacterial, light admitting, and flexible properties, the nanocomposite antibacterial film is considered to be of great potential in applications.

  20. Silver nanoparticle toxicity to Daphnia magna is a function of dissolved silver concentration.

    PubMed

    Newton, Kim M; Puppala, Hema L; Kitchens, Christopher L; Colvin, Vicki L; Klaine, Stephen J

    2013-10-01

    The most persistent question regarding the toxicity of silver nanoparticles (AgNPs) is whether this toxicity is due to the nanoparticles themselves or the silver ions (Ag(+)) they release. The present study investigates the role of surface coating and the presence of dissolved organic carbon on the toxicity of AgNPs to Daphnia magna and tests the hypothesis that the acute toxicity of AgNPs is a function of dissolved Ag produced by nanoparticle dissolution. Toxicity of silver nitrate (AgNO3) and AgNPs with surface coatings-gum arabic (AgGA), polyethylene glycol (AgPEG), and polyvinylpyrrolidone (AgPVP)-at 48 h was assessed in US Environmental Protection Agency moderately hard reconstituted water alone and augmented with Suwannee River dissolved organic carbon (DOC). As expected, AgNO3 was the most toxic to D. magna and AgPVPs were the least toxic. In general, Suwannee River DOC presence reduced the toxicity of AgNO3, AgGAs, and AgPEG, while the toxicity of AgPVPs was unaffected. The measured dissolved Ag concentrations for all AgNPs and AgNO3 at the 48-h median lethal concentration in moderately hard reconstituted water were similar. The presence of Suwannee River DOC decreased the ratio of measured dissolved Ag to measured total Ag concentration. These results support the hypothesis that toxicity of AgNPs to D. magna is a function of dissolved Ag concentration from these particles.

  1. Antibacterial activity and synergistic effect of biosynthesized AgNPs with antibiotics against multidrug-resistant biofilm-forming coagulase-negative staphylococci isolated from clinical samples.

    PubMed

    Thomas, Roshmi; Nair, Aswathi P; Kr, Soumya; Mathew, Jyothis; Ek, Radhakrishnan

    2014-05-01

    Silver nanoparticles form promising template for designing antimicrobial agents against drug resistant pathogenic microorganisms. Thus, the development of a reliable green approach for the synthesis of nanoparticles is an important aspect of current nanotechnology research. In the present investigation, silver nanoparticles synthesized by a soil Bacillus sp. were characterized using UV-vis spectroscopy, FTIR, SEM, and EDS. The antibacterial potential of biosynthesized silver nanoparticles, standard antibiotics, and their conjugates were evaluated against multidrug-resistant biofilm-forming coagulase-negative S. epidermidis strains, S. aureus, Salmonella Typhi, Salmonella Paratyphi, and V. cholerae. Interestingly, silver nanoparticles (AgNPs) showed remarkable antibacterial activity against all the test strains with the highest activity against S. epidermidis strains 145 and 152. In addition, the highest synergistic effect of AgNPs was observed with chloramphenicol against Salmonella typhi. The results of the study clearly indicate the promising biomedical applications of biosynthesized AgNPs.

  2. 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.

  3. Functional analyses of nanoparticle toxicity: a comparative study of the effects of TiO2 and Ag on tomatoes (Lycopersicon esculentum).

    PubMed

    Song, Uhram; Jun, Heeju; Waldman, Bruce; Roh, Jinkyu; Kim, Younghun; Yi, Jongheop; Lee, Eun Ju

    2013-07-01

    Engineered nanoparticles (NPs), increasingly used in industry, enter and migrate through biological ecosystems. NPs may create some acute toxicity, but their overall effects on living organisms remain largely unknown. In particular, the behavior of NPs in natural conditions and their consequent ecological effects are still poorly understood. In this study, we developed methods to test the phytotoxicity of two distinctly different NPs, one aerosol (nano-TiO2), and the other colloidal silver (AgNP), by specifically considering their tendencies to agglomerate and form precipitates. First we examined effects of these NPs on germination and root elongation. While exposure to neither of these NPs resulted in acute toxicity on germination, silver NPs caused significantly decreased root elongation at every concentration we tested. We found that the hydrodynamic diameters of AgNPs were much smaller than those of nano-TiO2, which induced higher uptake and phytotoxicity. Based on the agglomeration behavior of the NPs, greenhouse trials were run using commercial soil, for nano-TiO2, and Hoagland's solution, for AgNP. Phytotoxicity of silver NPs in the mature plants was demonstrated by lower chlorophyll contents, higher superoxide dismutase activity and less fruit productivity, while nano-TiO2 resulted in higher superoxide dismutase activity at the highest concentration (5000mg/kg). Both nano-TiO2 and AgNPs were taken up into plant stems, leaves and fruits. Our results suggest that further studies of the ecological effects of nanoparticles and steps to mitigate appropriate management strategies are required.

  4. 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 (H5L1) and 3,5-di(2',4'-dicarboxylphenyl)benzoic acid (H5L2), two novel porous Zn-MOFs, [Zn5(μ3-H2O)2(L1)2]·3DMA·4H2O (CTGU-3) and [Zn3(μ3-OH)L2(H2O)3]·H2O (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 [Zn5(μ3-H2O)2(RCO2)6] and [Zn3(μ3-OH)(RCO2)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.

  5. A review of reproductive and developmental toxicity of silver nanoparticles in laboratory animals.

    PubMed

    Ema, Makoto; Okuda, Hirokazu; Gamo, Masashi; Honda, Kazumasa

    2017-01-01

    We summarized significant effects reported in the literature on the reproductive and developmental toxicity of silver nanoparticles (AgNPs) in laboratory animals. AgNPs showed testicular/sperm toxicity in males and ovarian and embryonic toxicity in females. Maternal injection of AgNPs delayed physical development and impaired cognitive behavior in offspring. Ag was accumulated in the testes after administration of AgNPs. AgNPs were identified in the visceral yolk sac after administration during early gestation in mice. Radiolabeled AgNPs were detected in placenta, breast milk, and pre- and postnatal offspring after injection during late gestation in rats. Ag in the ionic form, and possibly also particles, was suggested to be bioavailable. Although this review provides initial information on the potential reproductive and developmental toxicity of AgNPs, data is still very limited. Further studies using state-of-the-art methodologies and the relevant routes and doses for human exposure are required.

  6. Sunlight-driven reduction of silver ion to silver nanoparticle by organic matter mitigates the acute toxicity of silver to Daphnia magna.

    PubMed

    Zhang, Zhen; Yang, Xiaoya; Shen, Mohai; Yin, Yongguang; Liu, Jingfu

    2015-09-01

    Due to the unique antibacterial activities, silver nanoparticles (AgNPs) have been extensively used in commercial products. Anthropogenic activities have released considerable AgNPs as well as highly toxic silver ion (Ag(+)) into the aquatic environment. Our recent study revealed that ubiquitous natural organic matter (NOM) could reduce Ag(+) to AgNP under natural sunlight. However, the toxic effect of this process is not well understood. In this work, we prepared mixture solution of Ag(+) and AgNPs with varied Ag(+)% through the sunlight-driven reduction of Ag(+) by NOM and investigated the acute toxicity of the solutions on Daphnia magna. Formation of AgNPs was demonstrated and characterized by comprehensive techniques and the fraction of unconverted Ag(+) was determined by ultrafiltration-inductively coupled plasma mass spectrometry determination. The formation of AgNPs enhanced significantly with the increasing of solution pH and cumulative photosynthetically active radiation of sunlight. The toxicity of the resulting solution was further investigated by using freshwater crustacean D. magna as a model and an 8hr-median lethal concentration (LC50) demonstrated that the reduction of Ag(+) by NOM to AgNPs significantly mitigated the acute toxicity of silver. These results highlight the importance of sunlight and NOM in the fate, transformation and toxicity of Ag(+) and AgNPs, and further indicate that the acute toxicity of AgNPs should be mainly ascribed to the dissolved Ag(+) from AgNPs.

  7. A mixture toxicity approach to predict the toxicity of Ag decorated ZnO nanomaterials.

    PubMed

    Azevedo, S L; Holz, T; Rodrigues, J; Monteiro, T; Costa, F M; Soares, A M V M; Loureiro, S

    2017-02-01

    Nanotechnology is a rising field and nanomaterials can now be found in a vast variety of products with different chemical compositions, sizes and shapes. New nanostructures combining different nanomaterials are being developed due to their enhancing characteristics when compared to nanomaterials alone. In the present study, the toxicity of a nanostructure composed by a ZnO nanomaterial with Ag nanomaterials on its surface (designated as ZnO/Ag nanostructure) was assessed using the model-organism Daphnia magna and its toxicity predicted based on the toxicity of the single components (Zn and Ag). For that ZnO and Ag nanomaterials as single components, along with its mixture prepared in the laboratory, were compared in terms of toxicity to ZnO/Ag nanostructures. Toxicity was assessed by immobilization and reproduction tests. A mixture toxicity approach was carried out using as starting point the conceptual model of Concentration Addition. The laboratory mixture of both nanomaterials showed that toxicity was dependent on the doses of ZnO and Ag used (immobilization) or presented a synergistic pattern (reproduction). The ZnO/Ag nanostructure toxicity prediction, based on the percentage of individual components, showed an increase in toxicity when compared to the expected (immobilization) and dependent on the concentration used (reproduction). This study demonstrates that the toxicity of the prepared mixture of ZnO and Ag and of the ZnO/Ag nanostructure cannot be predicted based on the toxicity of their components, highlighting the importance of taking into account the interaction between nanomaterials when assessing hazard and risk.

  8. Effects of PVP/PEI coated and uncoated silver NPs and PVP/PEI coating agent on three species of marine microalgae.

    PubMed

    Schiavo, S; Duroudier, N; Bilbao, E; Mikolaczyk, M; Schäfer, J; Cajaraville, M P; Manzo, S

    2017-01-15

    In the last years, applications for silver nanoparticles (Ag NPs) continue to increase together with the concerns about their potential input and hazards in aquatic ecosystems, where microalgae are key organisms. The aim of the present study was to assess the relative sensitivity of three marine microalgae species with differences in cell wall composition/structure exposed to Poly N-vinyl-2-pirrolidone/Polyethyleneimine (PVP/PEI) coated 5nm Ag NPs and uncoated 47nm Ag NP. As limited attention has been paid to the role of coating agents in NP toxicity, the effect of PVP/PEI alone was also evaluated. After 72h in artificial seawater, 47nm Ag NPs formed around 1400nm size aggregates while PVP/PEI coated 5nm Ag NPs reached around 90nm. Ag(+) release in seawater was around 3% for 47nm Ag NPs and 30% for PVP/PEI coated 5nm Ag NPs. PVP/PEI coated 5nm Ag NP aggregates entrapped the algal cells in a network of heteroaggregates, while uncoated 47nm Ag NPs interacted to a lesser extent with algae. The concentration of PVP/PEI coated 5nm Ag NPs that exerted the median effect (EC50) on algae growth pointed out differences in algae sensitivity: T. suecica was about 10 times more sensitive than I. galbana and P. tricornutum. Further, the coating agent alone was as toxic to algae as PVP/PEI coated 5nm Ag NPs, suggesting that presence of the coating agent was the main driver of toxicity of coated NPs. Uncoated 47nm Ag NPs instead, showed similar toxicity towards algae although P. tricornutum was slightly less sensitive than T. suecica and I. galbana, which agrees with the presence of a resistant silicified cell wall in the diatom. The present work demonstrates differences in sensitivity of three marine microalgae, possibly related to their cell surface and size characteristics.

  9. 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.

  10. Size-dependent toxicity of silver nanoparticles to Glyptotendipes tokunagai

    PubMed Central

    Choi, Seona; Kim, Soyoun; Bae, Yeon-Jae; Park, June-Woo; Jung, Jinho

    2015-01-01

    Objectives This study aims to evaluate the size-dependent toxicity of spherical silver nanoparticles (Ag NPs) to an endemic benthic organism, Glyptotendipes tokunagai. Methods Ag nanoparticles of three nominal sizes (50, 100, and 150 nm) capped with polyvinyl pyrrolidone (PVP-Ag NPs) were used. Their physicochemical properties, acute toxicity (48 hours), and bioaccumulation were measured using third instar larvae of G. tokunagai. Results The aggregation and dissolution of PVP-Ag NPs increased with exposure time and concentration, respectively, particularly for 50 nm PVP-Ag NPs. However, the dissolved concentration of Ag ions was not significant compared with the median lethal concentration value for AgNO3 (3.51 mg/L). The acute toxicity of PVP-Ag NPs was highest for the smallest particles (50 nm), whereas bioaccumulation was greatest for the largest particles (150 nm). However, larger PVP-Ag NPs were absorbed and excreted rapidly, resulting in shorter stays in G. tokunagai than the smaller ones. Conclusions The size of PVP-Ag NPs significantly affects their acute toxicity to G. tokunagai. In particular, smaller PVP-Ag NPs have a higher solubility and stay longer in the body of G. tokunagai, resulting in higher toxicity than larger PVP-Ag NPs. PMID:26184045

  11. Organ-Specific and Size-Dependent Ag Nanoparticle Toxicity in Gills and Intestines of Adult Zebrafish.

    PubMed

    Osborne, Olivia J; Lin, Sijie; Chang, Chong Hyun; Ji, Zhaoxia; Yu, Xuechen; Wang, Xiang; Lin, Shuo; Xia, Tian; Nel, André E

    2015-10-27

    We studied adult zebrafish to determine whether the size of 20 and 110 nm citrate-coated silver nanoparticles (AgC NPs) differentially impact the gills and intestines, known target organs for Ag toxicity in fish. Following exposure for 4 h, 4 days, or 4 days plus a 7 day depuration period, we obtained different toxicokinetic profiles for different particle sizes, as determined by Ag content of the tissues. Ionic AgNO3 served as a positive control. The gills showed a significantly higher Ag content for the 20 nm particles at 4 h and 4 days than the 110 nm particles, while the values were more similar in the intestines. Both particle types were retained in the intestines even after depuration. These toxicokinetics were accompanied by striking size-dependent differences in the ultrastructural features and histopathology in the target organs in response to the particulates. Ag staining of the gills and intestines confirmed prominent Ag deposition in the basolateral membranes for the 20 nm but not for the 110 nm particles. Furthermore, it was possible to link the site of tissue deposition to disruption of the Na(+)/K(+) ion channel, which is also localized to the basolateral membrane. This was confirmed by a reduction in ATPase activity and immunohistochemical detection of the α subunit of this channel in both target organs, with the 20 nm particles causing significantly higher inhibition and disruption than the larger size particles or AgNO3. These results demonstrate the importance of particle size in determining the hazardous impact of AgNPs in the gills and intestines of adult zebrafish.

  12. CeO2 NPs, toxic or protective to phytoplankton? Charge of nanoparticles and cell wall as factors which cause changes in cell complexity.

    PubMed

    Sendra, M; Yeste, P M; Moreno-Garrido, I; Gatica, J M; Blasco, J

    2017-07-15

    CeO2 nanoparticles (CeO2 NPs) are well-known for their catalytic properties and antioxidant potential. Recent uses in therapy are based on the Ce(+3) ions released by CeO2 NPs. Reactions involving redox cycles between Ce(+3) and Ce(+4) oxidation stage seem to promote scavenging of reactive oxygen species (ROS), thus protecting cells from oxygen damage. However, the internalization of CeO2 NPs and release of Ce(+3) could be responsible for a toxic effect on cells. The literature reports controversial results on the toxicity of CeO2 NPs to phytoplankton. Therefore, we have tested the potential toxic effect of two CeO2 NPs (with positive and negative zeta potential) and bulk CeO2 (at 0.1, 1, 10, 100 and 200mg·L(-1)) on three species of microalgae from different environments: marine diatom (Phaeodactylum tricornutum), marine chlorophyte (Nannochloris atomus) and freshwater chlorophyte (Chlamydomonas reinhardtii) over 72h in batch cultures. Responses measured in the microalgae population are: growth, chlorophyll a, cell size, cell complexity, percentage of ROS, and percentage of cell membrane damage. Positive zeta potential CeO2 NPs provoked greater cell complexity (up to 78, 172 and 23 times more cell complexity than in controls found for C. reinhardtii, P. tricornutum and N. atomus respectively) than negative zeta potential CeO2 NPs. The SSC signal detected by flow cytometry measured increases of particles entering cells, and this is related to cell viability and levels of intracellular ROS (correlation between SSC and percentage of ROS of 0.72 and 0.97 found for C. reinhardtii and P. tricornutum). When increased cellular complexity over controls is between 2 and 6 times greater, CeO2 (in bulk or nanoparticulate form) seems to protect against ROS. When increased cellular complexity is from 7 to 23 times greater, CeO2 does not provoke toxic responses; however, when increased cellular complexity over controls is very high, from 61 to 172 times, increased ROS production

  13. Toxicity of silver ions and differently coated silver nanoparticles in Allium cepa roots.

    PubMed

    Cvjetko, Petra; Milošić, Anita; Domijan, Ana-Marija; Vinković Vrček, Ivana; Tolić, Sonja; Peharec Štefanić, Petra; Letofsky-Papst, Ilse; Tkalec, Mirta; Balen, Biljana

    2017-03-01

    Silver nanoparticles (AgNPs) are the dominating nanomaterial in consumer products due to their well-known antibacterial and antifungal properties. To enhance their properties, different surface coatings may be used, which affect physico-chemical properties of AgNPs. Due to their wide application, there has been concern about possible environmental and health consequences. Since plants play a significant role in accumulation and biodistribution of many environmentally released substances, they are also very likely to be influenced by AgNPs. In this study we investigated the toxicity of AgNO3 and three types of laboratory-synthesized AgNPs with different surface coatings [citrate, polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB)] on Allium cepa roots. Ionic form of Ag was confirmed to be more toxic than any of the AgNPs applied. All tested AgNPs caused oxidative stress and exhibited toxicity only when applied in higher concentrations. The highest toxicity was recorded for AgNPs-CTAB, which resulted with increased Ag uptake in the roots, consequently leading to strong reduction of the root growth and oxidative damage. The weakest impact was found for AgNPs-citrate, much bigger, negatively charged NPs, which also aggregated to larger particles. Therefore, we can conclude that the toxicity of AgNPs is directly correlated with their size, overall surface charge and/or surface coating.

  14. Effects of soil and dietary exposures to Ag nanoparticles and AgNO₃ in the terrestrial isopod Porcellionides pruinosus.

    PubMed

    Tourinho, Paula S; van Gestel, Cornelis A M; Jurkschat, Kerstin; Soares, Amadeu M V M; Loureiro, Susana

    2015-10-01

    The effects of Ag-NPs and AgNO3 on the isopod Porcellionides pruinosus were determined upon soil and dietary exposures. Isopods avoided Ag in soil, with EC50 values of ∼16.0 and 14.0 mg Ag/kg for Ag-NPs and AgNO3, respectively. Feeding inhibition tests in soil showed EC50s for effects on consumption ratio of 127 and 56.7 mg Ag/kg, respectively. Although similar EC50s for effects on biomass were observed for nanoparticulate and ionic Ag (114 and 120 mg Ag/kg dry soil, respectively), at higher concentrations greater biomass loss was found for AgNO3. Upon dietary exposure, AgNO3 was more toxic, with EC50 for effects on biomass change being >1500 and 233 mg Ag/kg for Ag-NPs and AgNO3, respectively. The difference in toxicity between Ag-NPs and AgNO3 could not be explained from Ag body concentrations. This suggests that the relation between toxicity and bioavailability of Ag-NPs differs from that of ionic Ag in soils.

  15. One-pot synthesis of GO/AgNPs/luminol composites with electrochemiluminescence activity for sensitive detection of DNA methyltransferase activity.

    PubMed

    Zhao, Hui-Fang; Liang, Ru-Ping; Wang, Jing-Wu; Qiu, Jian-Ding

    2015-01-15

    DNA methyltransferases catalyze the transfer of a methyl group from S-adenosylmethionine to the target adenine or cytosine, eventually inducing the DNA methylation in both prokaryotes and eukaryotes. Herein, we developed a novel electrochemiluminescence biosensor to quantify DNA adenine methylation (Dam) methyltransferase (MTase) employing signal amplification of GO/AgNPs/luminol composites to enhance the assay sensitivity. The method was developed by designing a capture probe DNA, which was immobilized on gold electrode surface, to hybridize with azide complementary DNA to form the azide-terminated dsDNA. Then, alkynyl functionalized GO/AgNPs/luminol composites as the signal probe were immobilized to azide-terminated dsDNA modified electrode via click chemistry, resulting in a high electrochemiluminescence (ECL) signal. Once the DNA hybrid was methylated (under catalysis of Dam MTase) and further cleaved by Dpn I endonuclease (a site-specific endonuclease recognizing the duplex symmetrical sequence of 5'-G-Am-T-C-3'), GO/AgNPs/luminol composites release from the electrode surface to the solution, leading to significant reduction of the ECL signal. The change of the ECL intensity is related to the methylation status and MTase activity, which forms the basis of MTase activity assay and site-specific methylation determination. This novel strategy can be further used as a universal method for other transferase determination by designing various transferase-specific DNA sequences. In addition, this method can be used for the screening of antimicrobial drugs and has a great potential to be further applied in early clinical diagnosis.

  16. 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.

  17. Enzyme-free colorimetric determination of EV71 virus using a 3D-MnO2-PEG nanoflower and 4-MBA-MA-AgNPs.

    PubMed

    Chu, Chengchao; Ge, Shengxiang; Zhang, Jing; Lin, Huirong; Liu, Gang; Chen, Xiaoyuan

    2016-09-15

    We present a simple colorimetric assay for EV71 virus detection based on the aggregation of 4-mercaptobenzoic acid (4-MBA) and melamine (MA) modified silver nanoparticles (4-MBA-MA-AgNPs) in the presence of Mn(2+). The EV71-Ab1 was incubated on a 96-well plate and the EV71-Ab2 was labeled on the surface of three-dimensional nanoflower-like MnO2-PEG (3D-MnO2-PEG). After layer-by-layer immunoreactions, the EV71 virus and the corresponding 3D-MnO2-PEG-Ab2 were captured on the plate. With the addition of Vitamin C (Vc), Mn(2+) was released from the 3D-MnO2-PEG and then the aggregation of the 4-MBA-MA-AgNPs was induced, allowing a naked-eye detection limit of EV71 virus to be as low as 5 × 10(4) particles per mL, which is about three orders of magnitude lower than the conventional enzyme-linked immunosorbent assay (ELISA). This enzyme-free immunoassay based on a hybrid 3D-MnO2 features signal amplification strategies via a simple reduction reaction.

  18. 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.

  19. Silver nanoparticle gated, mesoporous silica coated gold nanorods (AuNR@MS@AgNPs): low premature release and multifunctional cancer theranostic platform.

    PubMed

    Zhang, Zhehua; Liu, Changhui; Bai, Junhui; Wu, Cuichen; Xiao, Yue; Li, Yinhui; Zheng, Jing; Yang, Ronghua; Tan, Weihong

    2015-03-25

    Multifunctional nanoparticles integrated with an imaging module and therapeutic drugs are promising candidates for future cancer diagnosis and therapy. Mesoporous silica coated gold nanorods (AuNR@MS) have emerged as a novel multifunctional cancer theranostic platform combining the large specific surface area of mesoporous silica, which guarantees a high drug payload, and the photothermal modality of AuNRs. However, premature release and side effects of exogenous stimulus still hinder the further application of AuNR@MS. To address these issues, herein, we proposed a glutathione (GSH)-responsive multifunctional AuNR@MS nanocarrier with in situ formed silver nanoparticles (AgNPs) as the capping agent. The inner AuNR core functions as a hyperthermia agent, while the outer mesoporous silica shell exhibits the potential to allow a high drug payload, thus posing itself as an effective drug carrier. With the incorporation of targeting aptamers, the constructed nanocarriers show drug release in accordance with an intracellular GSH level with maximum drug release into tumors and minimum systemic release in the blood. Meanwhile, the photothermal effect of the AuNRs upon application to near-infrared (NIR) light led to a rapid rise in the local temperature, resulting in an enhanced cell cytotoxicity. Such a versatile theranostic system as AuNR@MS@AgNPs is expected to have a wide biomedical application and may be particularly useful for cancer therapy.

  20. Citrate coated silver nanoparticles change heavy metal toxicities and bioaccumulation of Daphnia magna.

    PubMed

    Kim, Injeong; Lee, Byung-Tae; Kim, Hyun-A; Kim, Kyoung-Woong; Kim, Sang Don; Hwang, Yu-Sik

    2016-01-01

    Citrate-coated AgNPs (c-AgNPs) have negatively charged surfaces and their surface interactions with heavy metals can affect metal toxicity in aquatic environments. This study used Daphnia magna to compare the acute toxicities and bioaccumulation of As(V), Cd, and Cu when they interact with c-AgNPs. The 24-h acute toxicities of As(V) and Cu were not affected by the addition of c-AgNPs, while bioaccumulation significantly decreased in the presence of c-AgNPs. In contrast, both the 24-h acute toxicity and bioaccumulation of Cd increased in the presence of c-AgNPs. These toxicity and bioaccumulation trends can be attributed to the interactions between the AgNP surface and the heavy metals. As(V) and c-AgNPs compete by negative charge, decreasing As(V) toxicity. Copper adheres readily to c-AgNP citrate, decreasing Cu bioavailability, and thus reducing Cu toxicity and bioaccumulation. Citrate complexes with divalent cations such as Ca and Mg reduce the competition between divalent cations and Cd on biotic ligand, increasing toxicity and bioaccumulation of Cd. This study shows that surface properties determine the effect of c-AgNPs on heavy metal toxicities and bioaccumulations; hence, further studies on the effect of nanoparticle by it surface properties are warranted.

  1. Multiplex paper-based colorimetric DNA sensor using pyrrolidinyl peptide nucleic acid-induced AgNPs aggregation for detecting MERS-CoV, MTB and HPV oligonucleotides.

    PubMed

    Tee-Ngam, Prinjaporn; Siangproh, Weena; Tuantranont, Adisorn; Vilaivan, Tirayut; Chailapakul, Orawon; Henry, Charles S

    2017-04-10

    The development of simple fluorescent and colorimetric assays that enable point-of-care DNA and RNA detection has been a topic of significant research because of the utility of such assays in resource limited settings. The most common motifs utilize hybridization to a complementary detection strand coupled with a sensitive reporter molecule. Here, apaper-based colorimetric assay for DNA detection based on pyrrolidinyl peptide nucleic acid (acpcPNA)-induced nanoparticle aggregationis reported as an alternative to traditional colorimetric approaches. PNA probes are an attractive alternative to DNA and RNA probes because they are chemically and biologically stable, easily synthesized, and hybridize efficiently with the complementary DNA strands. The acpcPNA probe contains a single positive charge from the lysine at C-terminus and causes aggregation of citrate anion-stabilized silver nanoparticles (AgNPs) in the absence of complementary DNA. In the presence of target DNA, formation of the anionic DNA-acpcPNA duplex results in dispersion of the AgNPs as a result of electrostatic repulsion, giving rise to a detectable color change. Factors affecting the sensitivity and selectivity of this assay were investigated, including ionic strength, AgNP concentration, PNA concentration, and DNA strand mismatches. The method was used for screening of synthetic Middle East respiratory syndrome coronavirus (MERS-CoV), mycobacterium tuberculosis (MTB) and human papillomavirus (HPV)DNA based on a colorimetric paper-based analytical device developed using the aforementioned principle. The oligonucleotide targets were detected by measuring the color change of AgNPs, giving detection limits of 1.53 nM (MERS-CoV), 1.27 nM (MTB) and 1.03 nM (HPV).The acpcPNA probe exhibited high selectivity for the complementary oligonucleotides over single-base-mismatch, two-base-mismatch and non-complementary DNA targets. The proposed paper-based colorimetric DNA sensor has potential to be an alternative

  2. 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.

  3. 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.

  4. Meglumine antımoniate-TiO2@Ag nanoparticle combinations reduce toxicity of the drug while enhancing its antileishmanial effect.

    PubMed

    Abamor, Emrah Sefik; Allahverdiyev, Adil M; Bagirova, Melahat; Rafailovich, Miriam

    2017-05-01

    Currently, the treatment of leishmaniasis is increasingly insufficient as current antileishmanial drugs have many disadvantages such as toxic side effects, high cost, and growing drug resistance. In order to overcome these disadvantages, researchers have recently focused on combination therapy by using pentavalent antimonials in conjunction with other antileihmanial compounds. Our previous study found that TiO2@Ag nanoparticles (TiAgNps) demonstrated significant antileishmanial effects. However, a lethal dose of TiAgNps on L. topica promastigotes was found to be toxic for macrophage cells. Moreover, non-toxic concentrations of TiAgNps were ineffective in inhibiting L. topica promastigotes and amastigotes. Thus, we propose the use of TiAgNps in combination with other antileishmanial compounds like meglumine antimoniate (MA) at non-toxic concentrations, which may increase the efficacies of both agents and decrease their toxicities. Therefore, the aim of this study was to determine in vitro and in vivo antileishmanial efficacies of TiAgNps-MA combinations at non-toxic concentrations and develop a new approach for treatment that lowers the toxicities of pentavalent antimonials to minimal levels and enhances their effectiveness. In vitro screening was performed on L. topica promastigote and amastigote-macropage culture by using MTT assay to determine proliferation, perform infection index analysis, and to conduct a Griess reaction for nitric oxide production, while in vivo antileishmanial assays were applied on Balb/c mice with CL models. The results demonstrated that combinations including TiAgNps and MA at non-toxic concentrations were highly efficacious against both promastigotes and amastigotes, while MA application alone did not show any inhibitory effects. It was determined that combination applications decreased the proliferation of L. topica promastigotes 2- to 5-fold in contrast to use of MA alone, and was dependent on concentrations. Moreover, the use of

  5. Large-scale homogeneously distributed Ag-NPs with sub-10 nm gaps assembled on a two-layered honeycomb-like TiO2 film as sensitive and reproducible SERS substrates.

    PubMed

    Hu, Xiaoye; Meng, Guowen; Huang, Qing; Xu, Wei; Han, Fangming; Sun, Kexi; Xu, Qiaoling; Wang, Zhaoming

    2012-09-28

    We present a surface-enhanced Raman scattering (SERS) substrate featured by large-scale homogeneously distributed Ag nanoparticles (Ag-NPs) with sub-10 nm gaps assembled on a two-layered honeycomb-like TiO(2) film. The two-layered honeycomb-like TiO(2) film was achieved by a two-step anodization of pure Ti foil, with its upper layer consisting of hexagonally arranged shallow nano-bowls of 160 nm in diameter, and the lower layer consisting of arrays of about fifty vertically aligned sub-20 nm diameter nanopores. The shallow nano-bowls in the upper layer divide the whole TiO(2) film into regularly arranged arrays of uniform hexagonal nano-cells, leading to a similar distribution pattern for the ion-sputtered Ag-NPs in each nano-cell. The lower layer with sub-20 nm diameter nanopores prevents the aggregation of the sputtered Ag-NPs, so that the Ag-NPs can get much closer with gaps in the sub-10 nm range. Therefore, large-scale high-density and quasi-ordered sub-10 nm gaps between the adjacent Ag-NPs were achieved, which ensures homogeneously distributed 'hot spots' over a large area for the SERS effect. Moreover, the honeycomb-like structure can also facilitate the capture of target analyte molecules. As expected, the SERS substrate exhibits an excellent SERS effect with high sensitivity and reproducibility. As an example, the SERS substrate was utilized to detect polychlorinated biphenyls (PCBs, a kind of persistent organic pollutants as global environmental hazard) such as 3,3',4,4'-pentachlorobiphenyl (PCB-77) with concentrations down to 10(-9) M. Therefore the large-scale Ag-NPs with sub-10 nm gaps assembled on the two-layered honeycomb-like TiO (2) film have potentials in SERS-based rapid trace detection of PCBs.

  6. Silver Nanoparticle Toxicity in the Embryonic Zebrafish is Governed by Particle Dispersion and Ionic Environment

    PubMed Central

    Wehmas, Leah; Tanguay, Robert L.

    2013-01-01

    The mechanism of action of silver nanoparticles (AgNPs) is unclear due to the particles’ strong tendency to agglomerate. Preventing agglomeration could offer precise control of the physicochemical properties that drive biological response to AgNPs. In an attempt to control agglomeration, we exposed zebrafish embryos to AgNPs of 20 or 110 nm core size, and polypyrrolidone (PVP) or citrate surface coatings in media of varying ionic strength. AgNPs remained unagglomerated in 62.5 μM CaCl2 (CaCl2) and ultrapure water (UP), but not in standard zebrafish embryo medium (EM). Zebrafish embryos developed normally in the low ionic strength environments of CaCl2 and UP. Exposure of embryos to AgNPs suspended in UP and CaCl2 resulted in higher toxicity than suspensions in EM. 20 nm AgNPs were more toxic than 110 nm AgNPs, and the PVP coating was more toxic than the citrate coating at the same particle core size. The silver tissue burden correlated well with observed toxicity but only for those exposures where the AgNPs remained unagglomerated. Our results demonstrate that size- and surface coating-dependent toxicity is a result of AgNPs remaining unagglomerated, and thus a critical-design consideration for experiments to offer meaningful evaluations of AgNP toxicity. PMID:23449170

  7. Uptake of silver nanoparticles and toxicity to early life stages of Japanese medaka (Oryzias latipes): effect of coating materials.

    PubMed

    Kwok, Kevin W H; Auffan, Melanie; Badireddy, Appala R; Nelson, Clay M; Wiesner, Mark R; Chilkoti, Ashutosh; Liu, Jie; Marinakos, Stella M; Hinton, David E

    2012-09-15

    Silver nanoparticles (AgNPs) with antimicrobial properties are perhaps the most deployed engineered nanomaterials in consumer products. Almost all AgNPs are coated with organic materials to enhance their dispersion in water. Contributions of coatings to the toxicity of NPs have received little attention. Studies using AgNPs with one of three different coating materials (citrate (Cit), gum arabic (GA), and polyvinylpyrrolidone (PVP)) showed significantly different toxicity. GA AgNP proved to be the most toxic, while PVP and Cit AgNP exhibited similar and lower toxicity. However, all AgNPs were about three to ten times less toxic than AgNO(3) when their toxicities were compared on a mass-concentration basis. Evidence for NP-specific toxicity was observed with longer time for initiation of toxicity and increased incidence of resultant spinal flexure of medaka exposed to AgNPs, compared to AgNO(3). Hyperspectral imaging of 6 μm paraffin sections of fish exposed to AgNPs revealed AgNPs and their aggregates in tissues of fish. Gill distribution was ubiquitous, while small amounts were found in other organs, including the liver and brain. AgNPs were observed regularly in the gut lumen, but rarely in mural elements and mesentery. These results suggest that while ingestion was common, gills were the principal sites of AgNP uptake. In conclusion, AgNPs is a source of toxic Ag ions, while itself contribute partially to its toxicity to fish, and which interact with skin surface and were taken up via the gills.

  8. Nanosilver-coated socks and their toxicity to zebrafish (Danio rerio) embryos.

    PubMed

    Gao, Jiejun; Sepúlveda, Maria S; Klinkhamer, Christopher; Wei, Alexander; Gao, Yu; Mahapatra, Cecon T

    2015-01-01

    Silver nanoparticles (AgNPs) are being incorporated and are known to be released from various consumer products such as textiles. However, no data are available on the toxicity of AgNPs released from any of these commercial products. In this study, we quantified total silver released from socks into wash water by inductively coupled plasma mass spectrometry (ICP-MS) and determined the presence of AgNPs using transmission electron microscopy (TEM). We then exposed zebrafish (Danio rerio) embryos for 72 h to either this leachate ("sock-AgNP") or to the centrifugate ("spun-AgNP") free of AgNPs and compared their toxicity to that of ionic silver (Ag(+)). Our data suggest that AgNPs do get released into the wash water, and centrifugation eliminated AgNPs but did not decrease total silver concentrations, indicating that most of the silver in the sock-AgNP solution was in the ionic form. All embryos died during the first 24 h when exposed to undiluted sock-AgNP and spun-AgNP solutions resulting in significantly lower LC50 values (0.14 and 0.26 mg L(-1)) compared to AgNO3 (0.80 mg L(-1)). Similarly, at 72 hpf, both sock-derived solutions were more potent at affecting hatching and inducing abnormal development. These results suggest that both sock-AgNP and spun-AgNP solutions were more toxic than AgNO3. Previous studies have consistently shown the opposite, i.e., AgNPs are about 10 times less toxic that Ag(+). All together our results show that the high toxicity induced by the leachate of these socks is likely not caused by AgNPs or Ag(+). More studies are needed to evaluate the toxicity of the myriad of AgNP-coated commercial products that are now estimated to be close to 500.

  9. A highly reproducible and sensitive fiber SERS probe fabricated by direct synthesis of closely packed AgNPs on the silanized fiber taper.

    PubMed

    Cao, Jie; Zhao, Di; Mao, Qinghe

    2017-01-27

    A surface-enhanced Raman scattering (SERS) tapered fiber probe has been developed by using a chemically-etched tapered fiber tip and silanization of the surface of the fiber taper, followed by the hydrothermal growth of silver nanoparticles (AgNPs) on the silanized fiber taper. 4-Aminothiophenol (4-ATP) was selected as the target analyte to study the SERS responses of the prepared fiber SERS probe in an optrode remote detection mode. The experimental results show that the prepared fiber probe exhibited the ability to detect the 4-ATP molecule at a concentration as low as 10(-9) M and good reproducibility with the relative standard deviation (RSD) values being less than 9.1% for the strongest Raman peak. This work gives a novel and reliable way to realize a fiber SERS probe with high sensitivity, long-term stability, good reproducibility, and superior recyclability, exhibiting potential in SERS-based in situ detection application.

  10. Effects of water chemistry and surface contact on the toxicity of silver nanoparticles to Bacillus subtilis.

    PubMed

    Yi, Jun; Cheng, Jinping

    2017-04-04

    The growing use of silver nanoparticles (AgNPs) has created concerns about its potential impacts on natural microbial communities. In this study, the physicochemical properties of AgNPs and its toxicity on natural bacteria Bacillus subtilis (B. subtilis) were investigated in aqueous conditions. The characterization data showed that AgNPs highly aggregated in aqueous conditions, and the hydrodynamic diameter of AgNPs in aqueous conditions was larger than its primary size. The studied AgNPs was less toxic to B. subtilis in estuarine water as compared to that in Milli-Q water and artificial seawater, which might be due to the observed enhanced aggregation of AgNPs in estuarine water. The toxicity of AgNPs to B. subtilis was greatly reduced when their surface contact was blocked by a dialysis membrane. Scanning electron microscope images showed that exposure contact to AgNPs resulted in damage of the microbial cell wall and enhanced formation of fibrillar structures. These results suggest that particle-cell contact is largely responsible for the observed toxicity of AgNPs in B. subtilis. This study can help to understand the potential impacts of AgNPs to natural microbes, especially in the complex aquatic environments.

  11. 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

  12. Effect of sulfidation and dissolved organic matters on toxicity of silver nanoparticles in sediment dwelling organism, Chironomus riparius.

    PubMed

    Lee, Si-Won; Park, Sun-Young; Kim, Younghun; Im, Hosub; Choi, Jinhee

    2016-05-15

    The properties, fate, and toxicity of silver nanoparticles (AgNPs) are readily modified in the environment. Thus, in order to predict the environmental impact of AgNPs, the toxicity test should be conducted to assess the interactions of AgNPs with environmental matrices. Dissolved organic matter (DOM) is known to mitigate AgNPs toxicity in natural systems, and it is also known that silver binds strongly to sulfur. Little is known, however, about the effect of sulfidation and to what extent it could compete with DOM in the sediment. We therefore investigated the effect of sulfide on a sediment dwelling organism, Chironomus riparius using ecotoxicity endpoints. We then investigated how sulfide and a combination of sulfide and DOM affect the toxicity of AgNPs in C. riparius. We also monitored the concentrations of silver in the water and sediment compartments, as well as in C. riparius tissue, in the presence and absence of sulfide. Finally, in order to investigate how sulfide and DOM affect the release of ions from AgNPs, we also monitored released Ag(+) in each treatment. In the presence of sulfide, AgNPs were found to be less toxic to C. riparius in acute and chronic endpoints than AgNPs alone, whereas DOM treatment did not modulate the toxicity of AgNPs. Sulfide treatment reduced the release of Ag(+) from AgNPs. Water-spiked AgNPs with sulfide were found to be more slowly incorporated into both sediment and larvae as compared to the AgNP alone. Overall, the results suggest that the presence of sulfide in sediment mitigates the ecotoxicity of AgNPs in C. riparius.

  13. Amino acid-dependent transformations of citrate-coated silver nanoparticles: impact on morphology, stability and toxicity.

    PubMed

    Shi, Junpeng; Sun, Xia; Zou, Xiaoyan; Zhang, Hongwu

    2014-08-17

    Humans face the risk of exposure to silver nanoparticles (AgNPs) due to their extensive application in consumer products. AgNPs can interact with many substances in the human body due to their chemically unstable nature and high activity properties, which might result in unknown hazards and even some serious diseases for humans. As the basic constituent element of human bodies, amino acids (AAs) differ in concentration and variety in different cells and tissues. Thus, understanding the transformation of citrate-coated AgNPs in the presence of AAs is crucial for determining their fate and toxicity in the human body. Our study focused on the transformation of the morphology, dissolution behavior and reaction product of AgNPs in different AA-containing systems and then evaluated the effect of these transformations on the cytotoxicity of AgNPs. The obtained results indicated that the addition of glycine with the lowest Ag(+) binding energy had little effect on the transformations and toxicity of AgNPs. While in the presence of histidine with higher Ag(+) binding energy, the Ag(+) release and particle size of AgNPs obviously increased. These transformations resulted in a decrease in the cytotoxicity of AgNPs due to the formation of Ag-His complex and the growth of AgNPs. Furthermore, l-cysteine with the highest Ag(+) binding energy could easily interact with AgNPs, transforming them completely to form [Ag(Cys)n](+) and Ag2S precipitates, which induced the largest decrease in AgNP toxicity. In summary, our results may provide useful information to understand the fate, transformation, and toxicity of citrate-coated AgNPs in the human body.

  14. SPR studies of the adsorption of silver/bovine serum albumin nanoparticles (Ag/BSA NPs) onto the model biological substrates.

    PubMed

    Bhan, Chandra; Brower, Tina Louise; Raghavan, Dharmaraj

    2013-07-15

    The primary objective of this study is to investigate the interactive forces that promote the adsorption of bio-conjugated nanoparticles onto proteins. To elucidate the interactive forces, we demonstrate an approach using synthetic and model biological surfaces to study adsorption of bio-conjugated nanoparticles. Real-time adsorption of BSA conjugated silver nanoparticles (Ag/BSA NPs) on the immobilized substrates was followed by surface plasmon resonance (SPR). The extent of adsorption of the nanoparticles on the synthetic surface was found to be larger for self-assembled monolayers (SAMs) with ionizable terminal groups and lower for SAMs with unionizable terminal groups. For model biological substrate, the extent of nanoparticles adsorption was found to relate to the pKa of immobilized proteins. For collagen immobilized substrate, the adsorption of Ag/BSA nanoparticles showed a significantly higher SPR response than that of free BSA. The extent of nanoparticles adsorption on the collagen immobilized substrate was also influenced by the type and concentration of electrolyte used in dispersing nanoparticles. Our findings indicate that the adsorption of nanoparticles to immobilized surface has contributions from electrostatic interactions, hydrophobic, and/or hydrogen bonding. This work provides the framework to study interactions that may arise when bio-conjugated nanoparticles are transported in biological systems.

  15. Size-Dependent Toxicity of Silver Nanoparticles to Bacteria, Yeast, Algae, Crustaceans and Mammalian Cells In Vitro

    PubMed Central

    Ivask, Angela; Kurvet, Imbi; Kasemets, Kaja; Blinova, Irina; Aruoja, Villem; Suppi, Sandra; Vija, Heiki; Käkinen, Aleksandr; Titma, Tiina; Heinlaan, Margit; Visnapuu, Meeri; Koller, Dagmar; Kisand, Vambola; Kahru, Anne

    2014-01-01

    The concept of nanotechnologies is based on size-dependent properties of particles in the 1–100 nm range. However, the relation between the particle size and biological effects is still unclear. The aim of the current paper was to generate and analyse a homogenous set of experimental toxicity data on Ag nanoparticles (Ag NPs) of similar coating (citrate) but of 5 different primary sizes (10, 20, 40, 60 and 80 nm) to different types of organisms/cells commonly used in toxicity assays: bacterial, yeast and algal cells, crustaceans and mammalian cells in vitro. When possible, the assays were conducted in ultrapure water to minimise the effect of medium components on silver speciation. The toxic effects of NPs to different organisms varied about two orders of magnitude, being the lowest (∼0.1 mg Ag/L) for crustaceans and algae and the highest (∼26 mg Ag/L) for mammalian cells. To quantify the role of Ag ions in the toxicity of Ag NPs, we normalized the EC50 values to Ag ions that dissolved from the NPs. The analysis showed that the toxicity of 20–80 nm Ag NPs could fully be explained by released Ag ions whereas 10 nm Ag NPs proved more toxic than predicted. Using E. coli Ag-biosensor, we demonstrated that 10 nm Ag NPs were more bioavailable to E. coli than silver salt (AgNO3). Thus, one may infer that 10 nm Ag NPs had more efficient cell-particle contact resulting in higher intracellular bioavailability of silver than in case of bigger NPs. Although the latter conclusion is initially based on one test organism, it may lead to an explanation for “size-dependent“ biological effects of silver NPs. This study, for the first time, investigated the size-dependent toxic effects of a well-characterized library of Ag NPs to several microbial species, protozoans, algae, crustaceans and mammalian cells in vitro. PMID:25048192

  16. Mercury sensing and toxicity studies of novel latex fabricated silver nanoparticles.

    PubMed

    Borase, Hemant P; Patil, Chandrashekhar D; Salunkhe, Rahul B; Suryawanshi, Rahul K; Salunke, Bipinchandra K; Patil, Satish V

    2014-11-01

    Safe and eco-friendly alternatives to currently used hazardous chemico-physical methods of silver nanoparticles (AgNPs) synthesis are need of time. Rapid, low cost, selective detection of toxic metals in environmental sample is important to take safety action. Toxicity assessment of engineered AgNPs is essential to avoid its side effects on human and non-target organisms. In the present study, biologically active latex from Euphorbia heterophylla (Poinsettia) was utilized for synthesis of AgNPs. AgNPs was of spherical shape and narrow size range (20-50 nm). Occurrence of elemental silver and crystalline nature of AgNPs was analyzed. Role of latex metabolites in reduction and stabilization of AgNPs was analyzed by FT-IR, protein coagulation test and phytochemical analysis. Latex-synthesized AgNPs showed potential in selective and sensitive detection of toxic mercury ions (Hg(2+)) with limit of detection around 100 ppb. Addition of Hg(2+) showed marked deviation in color and surface plasmon resonance spectra of AgNPs. Toxicity studies on aquatic non-target species Daphnia magna showed that latex-synthesized AgNPs (20.66 ± 1.52% immobilization) were comparatively very less toxic than chemically synthesized AgNPs (51.66 ± 1.52% immobilization). Similarly, comparative toxicity study on human red blood cells showed lower hemolysis (4.46 ± 0.01%) by latex-synthesized AgNPs as compared to chemically synthesized AgNPs causing 6.14 ± 0.01% hemolysis.

  17. Silver nanoparticle (AgNPs) doped gum acacia-gelatin-silica nanohybrid: an effective support for diastase immobilization.

    PubMed

    Singh, Vandana; Ahmed, Shakeel

    2012-03-01

    An effective carrier matrix for diastase alpha amylase immobilization has been fabricated by gum acacia-gelatin dual templated polymerization of tetramethoxysilane. Silver nanoparticle (AgNp) doping to this hybrid could significantly enhance the shelf life of the impregnated enzyme while retaining its full bio-catalytic activity. The doped nanohybrid has been characterized as a thermally stable porous material which also showed multipeak photoluminescence under UV excitation. The immobilized diastase alpha amylase has been used to optimize the conditions for soluble starch hydrolysis in comparison to the free enzyme. The optimum pH for both immobilized and free enzyme hydrolysis was found to be same (pH=5), indicating that the immobilization made no major change in enzyme conformation. The immobilized enzyme showed good performance in wide temperature range (from 303 to 323 K), 323 K being the optimum value. The kinetic parameters for the immobilized, (K(m)=10.30 mg/mL, V(max)=4.36 μmol mL(-1)min(-1)) and free enzyme (K(m)=8.85 mg/mL, V(max)=2.81 μmol mL(-1)min(-1)) indicated that the immobilization improved the overall stability and catalytic property of the enzyme. The immobilized enzyme remained usable for repeated cycles and did not lose its activity even after 30 days storage at 40°C, while identically synthesized and stored silver undoped hybrid lost its ~31% activity in 48 h. Present study revealed the hybrids to be potentially useful for biomedical and optical applications.

  18. Application of Multi-Species Microbial Bioassay to Assess the Effects of Engineered Nanoparticles in the Aquatic Environment: Potential of a Luminous Microbial Array for Toxicity Risk Assessment (LumiMARA) on Testing for Surface-Coated Silver Nanoparticles

    PubMed Central

    Jung, YounJung; Park, Chang-Beom; Kim, Youngjun; Kim, Sanghun; Pflugmacher, Stephan; Baik, Seungyun

    2015-01-01

    Four different manufactured surface-coated silver nanoparticles (AgNPs) with coating of citrate, tannic acid, polyethylene glycol, and branched polyethylenimine were used in this study. The toxicity of surface-coated AgNPs was evaluated by a luminous microbial array for toxicity risk assessment (LumiMARA) using multi-species of luminescent bacteria. The salt stability of four different AgNPs was measured by UV absorbance at 400 nm wavelength, and different surface-charged AgNPs in combination with bacteria were observed using scanning electron microscopy (SEM). Both branched polyethylenimine (BPEI)-AgNPs and polyethylene glycol (PEG)-AgNPs were shown to be stable with 2% NaCl (non-aggregation), whereas both citrate (Cit)-AgNPs and tannic acid (Tan)-AgNPs rapidly aggregated in 2% NaCl solution. The values of the 50% effective concentration (EC50) for BPEI-AgNPs in marine bacteria strains (1.57 to 5.19 mg/L) were lower than those for the other surface-coated AgNPs (i.e., Cit-AgNPs, Tan-AgNPs, and PEG-AgNPs). It appears that the toxicity of AgNPs could be activated by the interaction of positively charged AgNPs with the negatively charged bacterial cell wall from the results of LumiMARA. LumiMARA for toxicity screening has advantageous compared to a single-species bioassay and is applicable for environmental samples as displaying ranges of assessment results. PMID:26184279

  19. Toxicity, Bioaccumulation and Biotransformation of Silver Nanoparticles in Marine Organisms.

    EPA Science Inventory

    The toxicity, bioaccumulation and biotransformation of citrate and polyvinylpyrrolidone (PVP) coated silver nanoparticles (NPs) (AgNP-citrate and AgNP-PVP) in marine organisms via marine sediment exposure was investigated. Results from 7-d sediment toxicity tests indicate that Ag...

  20. Highly dynamic PVP-coated silver nanoparticles in aquatic environments: chemical and morphology change induced by oxidation of Ag(0) and reduction of Ag(+).

    PubMed

    Yu, Su-Juan; Yin, Yong-Guang; Chao, Jing-Bo; Shen, Mo-Hai; Liu, Jing-Fu

    2014-01-01

    The fast growing and abundant use of silver nanoparticles (AgNPs) in commercial products alerts us to be cautious of their unknown health and environmental risks. Because of the inherent redox instability of silver, AgNPs are highly dynamic in the aquatic system, and the cycle of chemical oxidation of AgNPs to release Ag(+) and reconstitution to form AgNPs is expected to occur in aquatic environments. This study investigated how inevitable environmentally relevant factors like sunlight, dissolved organic matter (DOM), pH, Ca(2+)/Mg(2+), Cl(-), and S(2-) individually or in combination affect the chemical transformation of AgNPs. It was demonstrated that simulated sunlight induced the aggregation of AgNPs, causing particle fusion or self-assembly to form larger structures and aggregates. Meanwhile, AgNPs were significantly stabilized by DOM, indicating that AgNPs may exist as single particles and be suspended in natural water for a long time or delivered far distances. Dissolution (ion release) kinetics of AgNPs in sunlit DOM-rich water showed that dissolved Ag concentration increased gradually first and then suddenly decreased with external light irradiation, along with the regeneration of new tiny AgNPs. pH variation and addition of Ca(2+) and Mg(2+) within environmental levels did not affect the tendency, showing that this phenomenon was general in real aquatic systems. Given that a great number of studies have proven the toxicity of dissolved Ag (commonly regarded as the source of AgNP toxicity) to many aquatic organisms, our finding that the effect of DOM and sunlight on AgNP dissolution can regulate AgNP toxicity under these conditions is important. The fact that the release of Ag(+) and regeneration of AgNPs could both happen in sunlit DOM-rich water implies that previous results of toxicity studies gained by focusing on the original nature of AgNPs should be reconsidered and highlights the necessity to monitor the fate and toxicity of AgNPs under more

  1. Comparison of toxicity of uncoated and coated silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Nguyen, K. C.; Seligy, V. L.; Massarsky, A.; Moon, T. W.; Rippstein, P.; Tan, J.; Tayabali, A. F.

    2013-04-01

    This study compares toxic effects of uncoated (20, 40, 60 and 80 nm) and OECD (Organization for Economic Co-operation and Development) standard citrate- and polyvinylpyrrolidone (PVP)-coated (10, 50, and 75 nm) silver nanoparticles (Ag-NPs) in J774A. 1 macrophage and HT29 epithelial cells. The cells were exposed to different concentrations (silver content) of Ag-NPs for 24 h. Analysis showed that uncoated Ag-NPs, at a concentration of 1 μg/ml, decreased cell viability by 20-40% and that 20 and 40 nm particles were 10% more cytotoxic than the 60 and 80 nm particles. In exposures to coated Ag-NPs, cell viability dropped at 25 μg/ml or higher concentrations, and the effects were also size-dependent. PVP-coated particles induced greater cytotoxicity than citrate-coated particles. Changes in sub-cellular architecture were observed in J774A. 1 cells upon exposure to test Ag-NPs. Furthermore, uncoated Ag-NPs (1 μg/mL) decreased the expression of selected cytokines including TNF-α, IL-1β, and IL-12 (p70) in J774A. 1 and IL-8 in HT29 cells. In contrast, both citrate- and PVP-coated Ag-NPs increased the expression of these cytokines at higher concentrations (25 μg/ml), and PVP-coated particles elevated cytokine levels the most. Moreover, while uncoated Ag-NPs resulted in decreased glutathione (GSH) content and increased superoxide dismutase (SOD) activity in test cells in a size-dependent manner at 1 μg/ml, coated Ag-NPs caused non-significant changes in GSH and SOD, even at the highest test concentrations. Lastly, uncoated (20 and 40 nm) at 1 μg/ml and coated Ag-NPs (10 nm PVP) at 50 μg/ml slightly increased the production of reactive oxygen species (ROS). Our data showed that uncoated Ag-NPs are more toxic than coated Ag-NPs. While uncoated Ag-NPs appear to suppress inflammatory responses and enhance oxidative stress in the test cells, coated Ag-NPs induce toxic effects through up-regulation of cytokines. Our findings support the toxicity of Ag-NPs as being size

  2. Photo-catalytic activity of Plasmonic Ag@AgCl nanoparticles (synthesized via a green route) for the effective degradation of Victoria Blue B from aqueous phase.

    PubMed

    Devi, Th Babita; Begum, Shamima; Ahmaruzzaman, M

    2016-07-01

    This study reports a green process for the fabrication of Ag@AgCl (silver@silver chloride) nanoparticles by using Aquilaria agallocha (AA) leaves juice without using any external reagents. The effect of various reaction parameters, such as reaction temperature, reaction time and concentration of Aquilaria agallocha leaves juice in the formation of nanoparticles have also been investigated. From the FTIR spectra of leaves juice and phytochemicals test, it was found that flavonoids present in the leaves are responsible for the reduction of Ag(+) ions to Ag(0) species and leads to the formation of Ag@AgCl NPs. The synthesized Ag@AgCl NPs were utilized for the removal of toxic and hazardous dyes, such as Victoria Blue B from aqueous phase. Approximately, 99.46% degradation of Victoria Blue B dye were observed with Ag@AgCl NPs. Furthermore, the photocatalytic activity of the Ag@AgCl nanoparticles was unchanged after 5cycles of operation.

  3. Phytotoxicity of Ag nanoparticles prepared by biogenic and chemical methods

    NASA Astrophysics Data System (ADS)

    Choudhury, Rupasree; Majumder, Manna; Roy, Dijendra Nath; Basumallick, Srijita; Misra, Tarun Kumar

    2016-06-01

    Silver nanoparticles (Ag NPs) are now widely used as antibacterial and antifungal materials in different consumer products. We report here the preparation of Ag NPs by neem leaves extract ( Azadirachta) reduction and trisodium citrate-sodium borohydride reduction methods, and study of their phytotoxicity. The nanoparticles were characterized by UV-Vis spectroscopy, FTIR, and atomic force microscopy (AFM) techniques. Both neem-coated and citrate-coated Ag NPs exhibit surface plasmon around 400 nm, and their average sizes measured by AFM are about 100 and 20 nm, respectively. Antibacterial and antifungal activities of these nanomaterials have been studied by simple pea seed germination and disk diffusion methods. It has been observed from the growth of root and shoot, citrate-coated Ag NPs significantly affect seedling growth, but neem-coated Ag NPs exhibit somehow mild toxicity toward germination process due to the nutrient supplements from neem. On the other hand, antifungal activity of neem-coated Ag NPs has been found much higher than that of citrate-coated Ag NPs due to the combined effects of antifungal activity of neem and Ag NPs. Present research primarily indicates a possible application of neem-coated Ag NPs as a potential fungicide.

  4. 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...

  5. 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.

  6. Characterization and In Vitro Toxicity of Copper Nanoparticles (Cu-NPs) in Murine Neuroblastoma (N2A) Cells

    DTIC Science & Technology

    2011-03-01

    declared a work of the United States Government and is not subject to copyright protection in the United States...Toxic Substance Control Act (EPA) Environmental Protection Agency (NIOSH) National Institute for Occupational Safety and...oxide) Zn, ZnO Skin Protectant , Sunscreen conversion efficiencies. Another area of energy research is in the area of fuel cells, because they

  7. Influence of bovine serum albumin and alginate on silver nanoparticle dissolution and toxicity to Nitrosomonas europaea.

    PubMed

    Ostermeyer, Ann-Kathrin; Kostigen Mumuper, Cameron; Semprini, Lewis; Radniecki, Tyler

    2013-12-17

    Bovine serum albumin (BSA), a model protein, reduced the toxicity of 20 nm citrate silver nanoparticles (AgNP) toward Nitrosomonas europaea, a model ammonia oxidizing bacteria, through a dual-mode protection mechanism. BSA reduced AgNP toxicity by chelating the silver ions (Ag(+)) released from the AgNPs. BSA further reduced AgNP toxicity by binding to the AgNP surface thus preventing NH3-dependent dissolution from occurring. Due to BSA's affinity toward Ag(+) chemisorbed on the AgNP surface, increased concentrations of BSA lead to increased AgNP dissolution rates. This, however, did not increase AgNP toxicity as the dissolved Ag(+) were adsorbed onto the BSA molecules. Alginate, a model extracellular polysaccharide (EPS), lacks strong Ag(+) ligands and was unable to protect N. europaea from Ag(+) toxicity. However, at high concentrations, alginate reduced AgNP toxicity by binding to the AgNP surface and reducing AgNP dissolution rates. Unlike BSA, alginate only weakly interacted with the AgNP surface and was unable to completely prevent NH3-dependent AgNP dissolution from occurring. Based on these results, AgNP toxicity in high protein environments (e.g., wastewater) is expected to be muted while the EPS layers of wastewater biofilms may provide additional protection from AgNPs, but not from Ag(+) that have already been released.

  8. Photo- and thermo-chemical transformation of AgCl and Ag2S in environmental matrices and its implication.

    PubMed

    Yin, Yongguang; Xu, Wei; Tan, Zhiqiang; Li, Yanbin; Wang, Weidong; Guo, Xiaoru; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2017-01-01

    AgCl and Ag2S prevalently exist in the environment as minerals and/or the chlorination and sulfidation products of ionic silver and elemental silver nanoparticles (AgNPs). In this work, we investigated the chemical transformation of AgCl and Ag2S under simulated sunlight (in water) and incineration (in sludge and simulated municipal solid waste, SMSW). In the presence of natural organic matter, AgCl in river water was observed to be transformed into AgNPs under simulated sunlight, while photo-reduction of Ag2S could not take place under the same experimental conditions. During the course of incineration, pure Ag2S was transformed into elemental silver while AgCl remained stable; however, both Ag2S in sludge and AgCl in SMSW can be transformed to elemental silver under incineration, evident by the results of X-ray absorption spectroscopy and scanning electron microscopy measurements. Incineration temperature played an important role in the transformation of Ag2S and AgCl into elemental silver. These results suggest that chemical transformations of Ag2S and AgCl into elemental silver could be a possible source of naturally occurring or unintentionally produced AgNPs, affecting the fate, transport, bioavailability and toxicity of silver. Therefore, it is necessary to include the contributions of this transformation process when assessing the risk of ionic silver/AgNPs and the utilization and management of incineration residues.

  9. Silver nanoparticle toxicity to Atlantic killifish (Fundulus heteroclitus) and Caenorhabditis elegans: a comparison of mesocosm, microcosm, and conventional laboratory studies.

    PubMed

    Bone, Audrey J; Matson, Cole W; Colman, Benjamin P; Yang, Xinyu; Meyer, Joel N; Di Giulio, Richard T

    2015-02-01

    The use of silver nanoparticles (AgNPs) in consumer products and industrial applications, as well as their recent detection in waste streams, has created concern about potential impacts on aquatic ecosystems. The effect of complex environmental media on AgNP toxicity was investigated using wetland mesocosms and smaller scale microcosms. Mesocosms were dosed with 2.5 mg Ag/L as gum arabic (GA)-coated AgNPs, polyvinylpyrrolidone (PVP)-coated AgNPs, or AgNO3. Water samples were taken from mesocosms 24 h after dosing for acute toxicity tests with embryos and larvae of Atlantic killifish (Fundulus heteroclitus) and the nematode Caenorhabditis elegans. Acute toxicity tests were also performed on Atlantic killifish with AgNO3, GA AgNPs, and PVP AgNPs prepared in the laboratory with similar water. For killifish embryos, mesocosm samples were much less toxic than laboratory samples for all types of silver. For larvae, in contrast, all 3 silver mesocosm treatments exhibited toxicity. Interestingly, mesocosm samples of AgNO3 were less toxic than laboratory samples; samples containing GA AgNPs were similar in toxicity, and samples containing PVP AgNPs were more toxic. For C. elegans, results were similar to killifish larvae. Results obtained from the mesocosms were not replicated on the smaller scale of the microcosms. These results indicate that environmental factors unique to the mesocosms acted differentially on AgNO3 to reduce its toxicity in a manner that does not translate to AgNPs for larval fish.

  10. Acute toxicity and accumulation of ZnO NPs in Ceriodaphnia dubia: Relative contributions of dissolved ions and particles.

    PubMed

    Bhuvaneshwari, M; Iswarya, V; Nagarajan, R; Chandrasekaran, N; Mukherjee, Amitava

    2016-08-01

    Although the ecotoxicological effects of various metal oxide nanoparticles on aquatic organisms are being actively studied, the contributions of particles and dissolved ions towards toxicity are still not well understood. The current study aims to assess the contribution of ZnO NP(particle) and ZnO NP(ion) to the overall toxicity and accumulation of ZnO NP(total) in Ceriodaphnia dubia. The aggregation and dissolution kinetics were studied for three different sizes (50nm, 100nm and bulk) of ZnO particles at 0.05, 0.12, 0.25 and 0.5mg/L concentrations in the sterile lake water medium at 6, 12, 24, and 48h intervals. The 48h LC50 of ZnO NP(total) was found to be 0.431, 0.605 and 0.701mg/L for 50, 100nm and bulk particles exposure. However, LC50 of Zn(ion) was found to be 1.048, 1.343 and 2.046mg/L for dissolved ions from different sizes (50nm, 100nm, and bulk) of ZnO particles. At LC50 concentration, the accumulation of 90-95% was noted for the NP(particles) across the sizes employed, while only about 4-5% contribution was from the NP(ion) to the overall accumulation NP(total). The relative contribution of ZnO NP(ion) to overall toxicity and accumulation was found to be lesser than that of ZnO NP(particles) across the sizes used in the study.

  11. Environmental transformations of silver nanoparticles: impact on stability and toxicity.

    PubMed

    Levard, Clément; Hotze, E Matt; Lowry, Gregory V; Brown, Gordon E

    2012-07-03

    Silver nanoparticles (Ag-NPs) readily transform in the environment, which modifies their properties and alters their transport, fate, and toxicity. It is essential to consider such transformations when assessing the potential environmental impact of Ag-NPs. This review discusses the major transformation processes of Ag-NPs in various aqueous environments, particularly transformations of the metallic Ag cores caused by reactions with (in)organic ligands, and the effects of such transformations on physical and chemical stability and toxicity. Thermodynamic arguments are used to predict what forms of oxidized silver will predominate in various environmental scenarios. Silver binds strongly to sulfur (both organic and inorganic) in natural systems (fresh and sea waters) as well as in wastewater treatment plants, where most Ag-NPs are expected to be concentrated and then released. Sulfidation of Ag-NPs results in a significant decrease in their toxicity due to the lower solubility of silver sulfide, potentially limiting their short-term environmental impact. This review also discusses some of the major unanswered questions about Ag-NPs, which, when answered, will improve predictions about their potential environmental impacts. Research needed to address these questions includes fundamental molecular-level studies of Ag-NPs and their transformation products, particularly Ag(2)S-NPs, in simplified model systems containing common (in)organic ligands, as well as under more realistic environmental conditions using microcosm/mesocosm-type experiments. Toxicology studies of Ag-NP transformation products, including different states of aggregation and sulfidation, are also required. In addition, there is the need to characterize the surface structures, compositions, and morphologies of Ag-NPs and Ag(2)S-NPs to the extent possible because they control properties such as solubility and reactivity.

  12. Capping Agent-Dependent Toxicity and Antimicrobial Activity of Silver Nanoparticles: An In Vitro Study. Concerns about Potential Application in Dental Practice

    PubMed Central

    Niska, Karolina; Knap, Narcyz; Kędzia, Anna; Jaskiewicz, Maciej; Kamysz, Wojciech; Inkielewicz-Stepniak, Iwona

    2016-01-01

    Objectives: In dentistry, silver nanoparticles (AgNPs) have drawn particular attention because of their wide antimicrobial activity spectrum. However, controversial information on AgNPs toxicity limited their use in oral infections. Therefore, the aim of the present study was to evaluate the antibacterial activities against a panel of oral pathogenic bacteria and bacterial biofilms together with potential cytotoxic effects on human gingival fibroblasts of 10 nm AgNPs: non-functionalized - uncapped (AgNPs-UC) as well as surface-functionalized with capping agent: lipoic acid (AgNPs-LA), polyethylene glycol (AgNPs-PEG) or tannic acid (AgNPs-TA) using silver nitrate (AgNO3) as control. Methods: The interaction of AgNPs with human gingival fibroblast cells (HGF-1) was evaluated using the mitochondrial metabolic potential assay (MTT). Antimicrobial activity of AgNPs was tested against anaerobic Gram-positive and Gram-negative bacteria isolated from patients with oral cavity and respiratory tract infections, and selected aerobic Staphylococci strains. Minimal inhibitory concentration (MIC) values were determined by the agar dilution method for anaerobic bacteria or broth microdilution method for reference Staphylococci strains and Streptococcus mutans. These strains were also used for antibiofilm activity of AgNPs. Results: The highest antimicrobial activities at nontoxic concentrations were observed for the uncapped AgNPs and the AgNPs capped with LA. It was found that AgNPs-LA and AgNPs-PEG demonstrated lower cytotoxicity as compared with the AgNPs-TA or AgNPs-UC in the gingival fibroblast model. All of the tested nanoparticles proved less toxic and demonstrated wider spectrum of antimicrobial activities than AgNO3 solution. Additionally, AgNPs-LA eradicated Staphylococcus epidermidis and Streptococcus mutans 1-day biofilm at concentration nontoxic to oral cells. Conclusions: Our results proved that a capping agent had significant influence on the antibacterial

  13. Capping Agent-Dependent Toxicity and Antimicrobial Activity of Silver Nanoparticles: An In Vitro Study. Concerns about Potential Application in Dental Practice.

    PubMed

    Niska, Karolina; Knap, Narcyz; Kędzia, Anna; Jaskiewicz, Maciej; Kamysz, Wojciech; Inkielewicz-Stepniak, Iwona

    2016-01-01

    Objectives: In dentistry, silver nanoparticles (AgNPs) have drawn particular attention because of their wide antimicrobial activity spectrum. However, controversial information on AgNPs toxicity limited their use in oral infections. Therefore, the aim of the present study was to evaluate the antibacterial activities against a panel of oral pathogenic bacteria and bacterial biofilms together with potential cytotoxic effects on human gingival fibroblasts of 10 nm AgNPs: non-functionalized - uncapped (AgNPs-UC) as well as surface-functionalized with capping agent: lipoic acid (AgNPs-LA), polyethylene glycol (AgNPs-PEG) or tannic acid (AgNPs-TA) using silver nitrate (AgNO3) as control. Methods: The interaction of AgNPs with human gingival fibroblast cells (HGF-1) was evaluated using the mitochondrial metabolic potential assay (MTT). Antimicrobial activity of AgNPs was tested against anaerobic Gram-positive and Gram-negative bacteria isolated from patients with oral cavity and respiratory tract infections, and selected aerobic Staphylococci strains. Minimal inhibitory concentration (MIC) values were determined by the agar dilution method for anaerobic bacteria or broth microdilution method for reference Staphylococci strains and Streptococcus mutans. These strains were also used for antibiofilm activity of AgNPs. Results: The highest antimicrobial activities at nontoxic concentrations were observed for the uncapped AgNPs and the AgNPs capped with LA. It was found that AgNPs-LA and AgNPs-PEG demonstrated lower cytotoxicity as compared with the AgNPs-TA or AgNPs-UC in the gingival fibroblast model. All of the tested nanoparticles proved less toxic and demonstrated wider spectrum of antimicrobial activities than AgNO3 solution. Additionally, AgNPs-LA eradicated Staphylococcus epidermidis and Streptococcus mutans 1-day biofilm at concentration nontoxic to oral cells. Conclusions: Our results proved that a capping agent had significant influence on the antibacterial

  14. Effect of chloride on the dissolution rate of silver nanoparticles and toxicity to E. coli.

    PubMed

    Levard, Clément; Mitra, Sumit; Yang, Tiffany; Jew, Adam D; Badireddy, Appala Raju; Lowry, Gregory V; Brown, Gordon E

    2013-06-04

    Pristine silver nanoparticles (AgNPs) are not chemically stable in the environment and react strongly with inorganic ligands such as sulfide and chloride once the silver is oxidized. Understanding the environmental transformations of AgNPs in the presence of specific inorganic ligands is crucial to determining their fate and toxicity in the environment. Chloride (Cl(-)) is a ubiquitous ligand with a strong affinity for oxidized silver and is often present in natural waters and in bacterial growth media. Though chloride can strongly affect toxicity results for AgNPs, their interaction is rarely considered and is challenging to study because of the numerous soluble and solid Ag-Cl species that can form depending on the Cl/Ag ratio. Consequently, little is known about the stability and dissolution kinetics of AgNPs in the presence of chloride ions. Our study focuses on the dissolution behavior of AgNPs in chloride-containing systems and also investigates the effect of chloride on the growth inhibition of E.coli (ATCC strain 33876) caused by Ag toxicity. Our results suggest that the kinetics of dissolution are strongly dependent on the Cl/Ag ratio and can be interpreted using the thermodynamically expected speciation of Ag in the presence of chloride. We also show that the toxicity of AgNPs to E.coli at various Cl(-) concentrations is governed by the amount of dissolved AgCl(x)((x-1)-) species suggesting an ion effect rather than a nanoparticle effect.

  15. Evaluation on the Toxic Effects of NanoAg to Catalase.

    PubMed

    Zhang, Bin; Zhai, Wenxin; Liu, Rutao; Yu, Zehua; Shen, Hengmei; Hu, Xinxin

    2015-02-01

    Protein is the functional actor of life. Research on protein damage induced by nanomaterials may give insight into the toxicity mechanisms of nanoparticles. Studying nano silver over the impact of the structure and function of catalase (CAT) at the molecular level, is of great significance for a comprehensive evaluation of their toxic effects. The toxic effects of nanoAg on catalase were thoroughly investigated using steady state and time resolved fluorescence quenching measurements, ultraviolet-visible absorption spectroscopy, resonance light scattering spectroscopy (RLS), circular dichroism spectroscopy (CD) and transmission electron microscopy (TEM). NanoAg could decrease the amount of alpha-helix and increase the beta sheet structure, leading to loose the skeleton structure of catalase. The characteristic fluorescence of catalase was obviously quenched, which showed the exposal of internal hydrophobic amino acids enhanced, and its quenching type is dynamic quenching. The result of RLS and TEM showed that the distribution and size of nanoAg become more uniform and smaller after their interaction, resulting in a decrease of RLS intensity. NanoAg could make the activity of catalase rise. By changing the structure of catalase, nanoAg increases its enzymatic activity to a certain extent, breaking down its balance in vivo, thereby affecting the normal physiological activities. NanoAg has obvious toxic effects on catalase. This paper provided a new perspective and method for the toxic effects of nanoAg to biological macromolecules; provided basic data and reference gist for the hygienics and toxicology studies of nanoAg. It is conducive to the toxicity prevention and control work of nanoAg, promoting nano-technology applied to human production and living better.

  16. Toxic potential of iron oxide, CdS/Ag₂S composite, CdS and Ag₂S NPs on a fresh water alga Mougeotia sp.

    PubMed

    Jagadeesh, E; Khan, Behlol; Chandran, Preethy; Khan, S Sudheer

    2015-01-01

    Nanoparticles (NPs) are being used in many industries ranging from medical, textile, automobile, consumer products, etc. This may increase the probability of their (NPs) release into the environment and fresh water ecosystems. The present study focuses on testing the potential effect of iron oxide, nanocomposite of cadmium sulfide and silver sulfide, cadmium sulfide and silver sulfide nanoparticles (NPs) on a fresh water alga Mougeotia sp. as the model organism. The alga was treated with different concentrations of NPs (0.1-25 mg/L). The NPs exposure caused lipid peroxidation and ROS production, and suppressed the antioxidant defense system such as catalase, glutathione reductase, and superoxide dismutase. Adsorption of NPs on algal surface and membrane damage were confirmed through microscopic evaluation and increase in protein content in extracellular medium. The present investigation pointed out the ecological implications of NPs. The study warrants the need for regulatory agencies to monitor and regulate the use of NPs.

  17. Low-dose toxicity of biogenic silver nanoparticles fabricated by Swertia chirata on root tips and flower buds of Allium cepa.

    PubMed

    Saha, Nirlipta; Dutta Gupta, S

    2017-02-09

    Chemically synthesized silver nanoparticles (chem-AgNPs) have been assessed extensively to show adverse effects on plant cells but the role of biologically synthesized nanoparticles (bio-AgNPs) at lower concentrations and their toxicological impact on plant cells have not been sufficiently studied. In this study, bio-AgNPs were prepared using aqueous leaf extracts of Swertia chirata. This AgNPs showed absorption peak at 440nm of the visible spectrum. TEM analysis revealed that the average size of AgNPs were 20nm and mainly spherical in shape. AFM topographic images depicted the three dimensional aspects of AgNPs. XRD analysis confirmed the crystalline nature. FTIR spectrum of the AgNPs revealed the possible biomolecules involved in bioreduction and efficient stabilization of the particles. Low-dose of bio-AgNPs concentrations (5, 10 and 20μgml(-1)) were used for toxicity studies on Allium cepa. The studies revealed that various chromosomal aberrations were induced in both mitotic and meiotic cells of Allium cepa even at lower concentrations of bio-AgNPs. Abnormalities in post meiotic products were also observed. Both mitotic and meiotic indexes decreased with increasing concentrations of bio-AgNPs in the treated cells. These findings implied that low dose bio-AgNPs can induce significant clastogenic effects on both meristematic and reproductive plant cells.

  18. Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies

    NASA Astrophysics Data System (ADS)

    Vinod Kumar, V.; Anbarasan, S.; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

    2014-08-01

    Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg2+, Cd2+ and Pb2+ metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

  19. Impacts of select organic ligands on the colloidal stability, dissolution dynamics, and toxicity of silver nanoparticles.

    PubMed

    Pokhrel, Lok R; Dubey, Brajesh; Scheuerman, Phillip R

    2013-11-19

    Key understanding of potential transformations that may occur on silver nanoparticle (AgNP) surface upon interaction with naturally ubiquitous organic ligands (e.g., -SH (thoil), humic acid, or -COO (carboxylate)) is limited. Herein we investigated how dissolved organic carbon (DOC), -SH (in cysteine, a well-known Ag(+) chelating agent), and -COO (in trolox, a well-known antioxidant) could alter the colloidal stability, dissolution rate, and toxicity of citrate-functionalized AgNPs (citrate-AgNPs) against a keystone crustacean Daphnia magna. Cysteine, DOC, or trolox amendment of citrate-AgNPs differentially modified particle size, surface properties (charge, plasmonic spectra), and ion release dynamics, thereby attenuating (with cysteine or trolox) or promoting (with DOC) AgNP toxicity. Except with DOC amendment, the combined toxicity of AgNPs and released Ag under cysteine or trolox amendment was lower than of AgNO3 alone. The results of this study show that citrate-AgNP toxicity can be associated with oxidative stress, ion release, and the organism biology. Our evidence suggests that specific organic ligands available in the receiving waters can differentially surface modify AgNPs and alter their environmental persistence (changing dissolution dynamics) and subsequently the toxicity; hence, we caveat to generalize that surface modified nanoparticles upon environmental release may not be toxic to receptor organisms.

  20. A double signal electrochemical human immunoglobulin G immunosensor based on gold nanoparticles-polydopamine functionalized reduced graphene oxide as a sensor platform and AgNPs/carbon nanocomposite as signal probe and catalytic substrate.

    PubMed

    Zhang, Si; Huang, Na; Lu, Qiujun; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2016-03-15

    In this paper, a double signal electrochemical Human immunoglobulin G (HIgG) immunosensor based on AgNPs/carbon nanocomposite (Ag/C NC) as the signal probe and catalytic substrate was developed for fast and sensitive detection of HIgG. The as-prepared AuNPs-PDA-rGO nanocomposite and Ag/C NC were confirmed by UV-vis, Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. Electrochemical impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical properties of the proposed immunosensor. The AuNPs-PDA-rGO nanocomposite can improve the electron transfer rate and capture more Ab1. In the sandwich-type immunoassay process, the Ag/C NC functionalized bioconjugates were captured on HIgG/Ab1/AuNPs-PDA-rGO surface and the electrochemical double-signal strategy was employed. These double electrochemical detection signals were directly monitored the oxidation current originated from Ag/C NC and indirectly detected the reduction current of benzoquinone which was produced from the reaction of H2O2 and HQ by catalysis of Ag/C NC in electrochemical detection of HIgG. Under the optimized conditions, the current responses were changed with the concentrations of HIgG for the proposed immunosensor with wide linear ranges of 0.1 to 100 ngmL(-1) and 0.01-100 ngmL(-1) with the lowest detection concentration of 0.001 ng mL(-1) in the absence and presence of H2O2 and HQ. The double-signal strategy is used for detection of HIgG, and the results came from the two signals were well consistent with each other. The proposed immunosensor was successfully applied in analysis of human IgG in real samples and this strategy may provide a relative simple and effective method for construction of other immunsensors in detection of other biomarkers in clinical medicine.

  1. Evaluation of nano-specific toxicity of zinc oxide, copper oxide, and silver nanoparticles through toxic ratio

    NASA Astrophysics Data System (ADS)

    Zhang, Weicheng; Liu, Xiawei; Bao, Shaopan; Xiao, Bangding; Fang, Tao

    2016-12-01

    For safety and environmental risk assessments of nanomaterials (NMs) and to provide essential toxicity data, nano-specific toxicities, or excess toxicities, of ZnO, CuO, and Ag nanoparticles (NPs) (20, 20, and 30 nm, respectively) to Escherichia coli and Saccharomyces cerevisiae in short-term (6 h) and long-term (48 h) bioassays were quantified based on a toxic ratio. ZnO NPs exhibited no nano-specific toxicities, reflecting similar toxicities as ZnO bulk particles (BPs) (as well as zinc salt). However, CuO and Ag NPs yielded distinctly nano-specific toxicities when compared with their BPs. According to their nano-specific toxicities, the capability of these NPs in eliciting hazardous effects on humans and the environment was as follows: CuO > Ag > ZnO NPs. Moreover, long-term bioassays were more sensitive to nano-specific toxicity than short-term bioassays. Overall, nano-specific toxicity is a meaningful measurement to evaluate the environmental risk of NPs. The log T e particle value is a useful parameter for quantifying NP nano-specific toxicity and enabling comparisons of international toxicological data. Furthermore, this value could be used to determine the environmental risk of NPs.

  2. In vitro studies of the toxic effects of silver nanoparticles on HeLa and U937 cells

    PubMed Central

    Kaba, Said I; Egorova, Elena M

    2015-01-01

    In the last decade, much attention has been paid to studies of the effect of silver nanoparticles (Ag NPs) on tumor cells. Apart from elucidation of the mechanism of NPs’ interaction with mammalian cells, these studies are aimed at discovering new effective antitumor drugs. In this work, we report about the toxic effects of Ag NPs observed on two types of tumor cells: HeLa (adhesive cells) and U937 (suspension cells). The Ag NPs were obtained by an original method of biochemical synthesis. Particle size was 13.2±4.72 nm, and zeta potential was −61.9±3.2 mV. The toxicity of Ag NPs in the concentration range 0.5–8.0 μg Ag/mL was determined by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and cytofluorometry after 4 and 24 hours’ incubation. It was found that Ag NPs had high toxicity toward both cell types. The minimal concentrations where a toxicity effect was registered (toxicity thresholds) lied in the range 0.5–2.0 μg Ag/mL. In parallel with the Ag NP solution, cells were incubated with water solutions of the NP stabilizer (aerosol-OT) and Ag+ ions (as silver nitrate). It was shown that aerosol-OT had no effect on the viability on HeLa cells, but was moderately toxic toward U937, though less dangerous for these cells than Ag NPs. With Ag+ ions, for HeLa no toxic effect was observed, while for U937 they were as toxic as the Ag NPs. The data obtained indicate that Ag NPs as used in this study may prove to be useful for the creation of medicines for cancer therapy. PMID:25784794

  3. Ranking the in vivo toxicity of nanomaterials in Drosophila melanogaster

    NASA Astrophysics Data System (ADS)

    Vecchio, G.; Galeone, A.; Malvindi, M. A.; Cingolani, R.; Pompa, P. P.

    2013-09-01

    In this work, we propose a quantitative assessment of nanoparticles toxicity in vivo. We show a quantitative ranking of several types of nanoparticles (AuNPs, AgNPs, cadmium-based QDs, cadmium-free QDs, and iron oxide NPs, with different coating and/or surface chemistries), providing a categorization of their toxicity outcomes. This strategy may offer an innovative high-throughput screening tool of nanomaterials, of potential and broad interest to the nanoscience community.

  4. An evaluation of acute toxicity of colloidal silver nanoparticles.

    PubMed

    Maneewattanapinyo, Pattwat; Banlunara, Wijit; Thammacharoen, Chuchaat; Ekgasit, Sanong; Kaewamatawong, Theerayuth

    2011-11-01

    Tests for acute oral toxicity, eye irritation, corrosion and dermal toxicity of colloidal silver nanoparticles (AgNPs) were conducted in laboratory animals following OECD guidelines. Oral administration of AgNPs at a limited dose of 5,000 mg/kg produced neither mortality nor acute toxic signs throughout the observation period. Percentage of body weight gain of the mice showed no significant difference between control and treatment groups. In the hematological analysis, there was no significant difference between mice treated with AgNPs and controls. Blood chemistry analysis also showed no differences in any of the parameter examined. There was neither any gross lesion nor histopathological change observed in various organs. The results indicated that the LD(50) of colloidal AgNPs is greater than 5,000 mg/kg body weight. In acute eye irritation and corrosion study, no mortality and toxic signs were observed when various doses of colloidal AgNPs were instilled in guinea pig eyes during 72 hr observation period. However, the instillation of AgNPs at 5,000 ppm produced transient eye irritation during early 24 hr observation time. No any gross abnormality was noted in the skins of the guinea pigs exposed to various doses of colloidal AgNPs. In addition, no significant AgNPs exposure relating to dermal tissue changes was observed microscopically. In summary, these findings of all toxicity tests in this study suggest that colloidal AgNPs could be relatively safe when administered to oral, eye and skin of the animal models for short periods of time.

  5. Toxicity and accumulation of silver nanoparticles during development of the marine polychaete Platynereis dumerilii

    USGS Publications Warehouse

    García-Alonso, Javier; Rodriguez-Sanchez, Neus; Misra, Superb K.; Valsami-Jones, Eugenia; Croteau, Marie-Noële; Luoma, Samuel N.; Rainbow, Philip S.

    2014-01-01

    Pollutants affecting species at the population level generate ecological instability in natural systems. The success of early life stages, such as those of aquatic invertebrates, is highly affected by adverse environmental conditions. Silver released into the environment from emerging nanotechnology represents such a threat. Sediments are sinks for numerous pollutants, which aggregate and/or associate with depositing suspended particles. Deposit feeder such as the annelid Platynereis dumerilii, which has a large associated literature on its development, is an excellent model organism for exposure studies in coastal environments. We exposed eggs, larvae, juveniles and adults of P. dumerilii to various concentrations of citrate (cit-Ag NPs) or humic acid (HA-Ag NPs) capped silver nanoparticles (Ag NPs) as well to dissolved Ag (added as AgNO3). We showed that mortality and abnormal development rate increased with younger life stages. While adults and juvenile were the most tolerant life stages, fertilized eggs were highly sensitive to AgNO3, cit-Ag NPs and HA-Ag NPs. Exposures to HA-Ag NPs triggered the highest cute toxicity responses in P. dumerilii and in most cases both Ag NPs were more toxic than AgNO3. Uptake rate of HA-Ag NPs in adult worms was also higher than from other Ag forms, consistent with toxicity to other life stages. The early stages of the life cycle of marine coastal organisms are more affected by Ag NPs than the juvenile or adult life stages, indicating that exposure experiments at the larval level contribute to realistic eco-toxicological studies in aquatic environments.

  6. Toxicity and accumulation of silver nanoparticles during development of the marine polychaete Platynereis dumerilii.

    PubMed

    García-Alonso, Javier; Rodriguez-Sanchez, Neus; Misra, Superb K; Valsami-Jones, Eugenia; Croteau, Marie-Noële; Luoma, Samuel N; Rainbow, Philip S

    2014-04-01

    Pollutants affecting species at the population level generate ecological instability in natural systems. The success of early life stages, such as those of aquatic invertebrates, is highly affected by adverse environmental conditions. Silver released into the environment from emerging nanotechnology represents such a threat. Sediments are sinks for numerous pollutants, which aggregate and/or associate with depositing suspended particles. Deposit feeder such as the annelid Platynereis dumerilii, which has a large associated literature on its development, is an excellent model organism for exposure studies in coastal environments. We exposed eggs, larvae, juveniles and adults of P. dumerilii to various concentrations of citrate (cit-Ag NPs) or humic acid (HA-Ag NPs) capped silver nanoparticles (Ag NPs) as well to dissolved Ag (added as AgNO3). We showed that mortality and abnormal development rate increased with younger life stages. While adults and juvenile were the most tolerant life stages, fertilized eggs were highly sensitive to AgNO3, cit-Ag NPs and HA-Ag NPs. Exposures to HA-Ag NPs triggered the highest cute toxicity responses in P. dumerilii and in most cases both Ag NPs were more toxic than AgNO3. Uptake rate of HA-Ag NPs in adult worms was also higher than from other Ag forms, consistent with toxicity to other life stages. The early stages of the life cycle of marine coastal organisms are more affected by Ag NPs than the juvenile or adult life stages, indicating that exposure experiments at the larval level contribute to realistic eco-toxicological studies in aquatic environments.

  7. Influence of silver nanoparticles on metabolism and toxicity of moulds.

    PubMed

    Pietrzak, Katarzyna; Twarużek, Magdalena; Czyżowska, Agata; Kosicki, Robert; Gutarowska, Beata

    2015-01-01

    The unique antimicrobial features of silver nanoparticles (AgNPs) are commonly applied in innumerable products. The lack of published studies on the mechanisms of AgNPs action on fungi resulted in identification of the aim of this study, which was: the determination of the influence of AgNPs on the mould cytotoxicity for swine kidney cells (MTT test) and the production of selected mycotoxins, organic acids, extracellular enzymes by moulds. The conducted study had shown that silver nanoparticles can change the metabolism and toxicity of moulds. AgNPs decrease the mycotoxin production of Aspergillus sp. (81-96%) and reduce mould cytotoxicity (50-75%). AgNPs influence the organic acid production of A. niger and P. chrysogenum by decreasing their concentration (especially of the oxalic and citric acid). Also, a change in the extracellular enzyme profile of A. niger and P. chrysogenum was observed, however, the total enzymatic activity was increased.

  8. Low-toxic Ag2S quantum dots for photoelectrochemical detection glucose and cancer cells.

    PubMed

    Zhang, Xiaoru; Liu, Mingshuai; Liu, Hongxia; Zhang, Shusheng

    2014-06-15

    A new photoelectrochemical (PEC) biosensor was developed using low-toxic Ag2S QDs as photoelectrochemically active species. Energy levels of Ag2S and Ag2Se QD were compared to explain their differences in the PEC performance. The preparation condition of Ag2S QD was optimized and its structure characterization was measured. Then the developed photoelectric active interface was used to detect glucose and MCF-7 cancer cell and showed the good sensitivity and specificity. Under optimal condition, detection limits of 3.2 × 10(-5)M for glucose and 98 cells/mL for MCF-7 cell were achieved. Thus, the prepared Ag2S QD could serve as an excellent and promising photoelectric active material in the PEC biosensor.

  9. Cadmium-free sugar-chain-immobilized fluorescent nanoparticles containing low-toxicity ZnS-AgInS2 cores for probing lectin and cells.

    PubMed

    Shinchi, Hiroyuki; Wakao, Masahiro; Nagata, Nonoka; Sakamoto, Masaya; Mochizuki, Eiko; Uematsu, Taro; Kuwabata, Susumu; Suda, Yasuo

    2014-02-19

    Sugar chains play a significant role in various biological processes through sugar chain-protein and sugar chain-sugar chain interactions. To date, various tools for analyzing sugar chains biofunctions have been developed. Fluorescent nanoparticles (FNPs) functionalized with carbohydrate, such as quantum dots (QDs), are an attractive imaging tool for analyzing carbohydrate biofunctions in vitro and in vivo. Most FNPs, however, consist of highly toxic elements such as cadmium, tellurium, selenium, and so on, causing problems in long-term bioimaging because of their cytotoxicity. In this study, we developed cadmium-free sugar-chain-immobilized fluorescent nanoparticles (SFNPs) using ZnS-AgInS2 (ZAIS) solid solution nanoparticles (NPs) of low or negligible toxicity as core components, and investigated their bioavailability and cytotoxicity. SFNPs were prepared by mixing our originally developed sugar-chain-ligand conjugates with ZAIS/ZnS core/shell NPs. In binding experiments with lectin, the obtained ZAIS/ZnS SFNPs interacted with an appropriate lectin to give specific aggregates, and their binding interaction was visually and/or spectroscopically detected. In addition, these SFNPs were successfully utilized for cytometry analysis and cellular imaging in which the cell was found to possess different sugar-binding properties. The results of the cytotoxicity assay indicated that SFNPs containing ZAIS/ZnS have much lower toxicity than those containing cadmium. These data strongly suggest that our designed SFNPs can be widely utilized in various biosensing applications involved in carbohydrates.

  10. NPS AUV Integrated Simulator

    DTIC Science & Technology

    1992-03-01

    147 3. GRAPHIC OBJECT MODEI’QUSING OBJECTFILE FORMAT (cIF)...................... ........... 149. APPENDIX -C. NPS, AUV SONAR CLASSIFICATION SYSTEM...Monterey Bay .. 15 Figure 2.8 Graphics simulation for NPS AUV sonar visualization .......... 15’ Figure 3.1 Integrated simulator network physical...3.11 Integrated simulation display of AUV minefield searh ........ 39 Figure4.1 NPS AUV sonar beam profiles in the NPS pool .......... 43 Figure 42 NPS

  11. Toxicological Effects of Caco-2 Cells Following Short-Term and Long-Term Exposure to Ag Nanoparticles

    PubMed Central

    Chen, Ni; Song, Zheng-Mei; Tang, Huan; Xi, Wen-Song; Cao, Aoneng; Liu, Yuanfang; Wang, Haifang

    2016-01-01

    Extensive utilization increases the exposure of humans to Ag nanoparticles (NPs) via the oral pathway. To comprehensively address the action of Ag NPs to the gastrointestinal systems in real situations, i.e., the long-term low-dose exposure, we evaluated and compared the toxicity of three Ag NPs (20–30 nm with different surface coatings) to the human intestine cell Caco-2 after 1-day and 21-day exposures, using various biological assays. In both the short- and long-term exposures, the variety of surface coating predominated the toxicity of Ag NPs in a descending order of citrate-coated Ag NP (Ag-CIT), bare Ag NP (Ag-B), and poly (N-vinyl-2-pyrrolidone)-coated Ag NP (Ag-PVP). The short-term exposure induced cell growth inhibition and death. The cell viability loss appeared after cells were exposed to 0.7 μg/mL Ag-CIT, 0.9 μg/mL Ag-B or >1.0 μg/mL Ag-PVP for 24 h. The short-term and higher-dose exposure also induced reactive oxygen species (ROS) generation, mitochondrial damage, cell membrane leakage, apoptosis, and inflammation (IL-8 level). The long-term exposure only inhibited the cell proliferation. After 21-day exposure to 0.4 μg/mL Ag-CIT, the cell viability dropped to less than 50%, while cells exposed to 0.5 μg/mL Ag-PVP remained normal as the control. Generally, 0.3 μg/mL is the non-toxic dose for the long-term exposure of Caco-2 cells to Ag NPs in this study. However, cells presented inflammation after exposure to Ag NPs with the non-toxic dose in the long-term exposure. PMID:27338357

  12. Difference in the toxicity mechanism between ion and nanoparticle forms of silver in the mouse lung and in macrophages.

    PubMed

    Arai, Yuta; Miyayama, Takamitsu; Hirano, Seishiro

    2015-02-03

    The health effects of silver nanoparticles (AgNPs) have not been well investigated, despite AgNPs now being widely used in consumer products. We investigated the metabolic behavior and toxicity of AgNPs in comparison to silver nitrate (AgNO3) both in vivo and in vitro. AgNPs (20 nm diameter) suspended in 1% albumin solution or AgNO3 solution was injected into the mouse lung. Less than 1% of the initial dose of AgNPs and more than 7% of the initial dose of AgNO3 was recovered in the liver 4h after administration, suggesting that the ionic form of silver was absorbed by the lung tissue and entered the systemic circulation more efficiently than AgNPs. The pro-inflammatory cytokine, IL-1β, and neutrophils in bronchoalveolar lavage fluid (BALF) increased following intratracheal instillation of AgNPs or AgNO3. AgNO3 recruited more neutrophils in the alveolar space than did AgNPs. In the in vitro study, AgNO3 was more cytotoxic than 20, 60, or 100 nm diameter AgNPs in a mouse macrophage cell line (J774.1). To investigate the intracellular distribution of Ag in detail, J774.1 cells were exposed to AgNO3 or 20 nm AgNPs and the distribution of Ag to cytosolic proteins was investigated using HPLC-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Ag was mainly distributed to metallothioneins (MT) and to high molecular weight proteins in AgNO3- and AgNPs-exposed cells, respectively. Confocal laser microscopic examination of LysoTracker(®)-labeled cells indicated that AgNPs were colocalized with lysosomes in J774.1 cells. These results suggest that AgNPs were transported to lysosomes and only gradually dissolved in the macrophages, causing milder inflammatory stimulation in the mouse lung compared to AgNO3.

  13. Cellular uptake and toxicity effects of silver nanoparticles in mammalian kidney cells.

    PubMed

    Milić, Mirta; Leitinger, Gerd; Pavičić, Ivan; Zebić Avdičević, Maja; Dobrović, Slaven; Goessler, Walter; Vinković Vrček, Ivana

    2015-06-01

    The rapid progress and early commercial acceptance of silver-based nanomaterials is owed to their biocidal activity. Besides embracing the antimicrobial potential of silver nanoparticles (AgNPs), it is imperative to give special attention to the potential adverse health effects of nanoparticles owing to prolonged exposure. Here, we report a detailed study on the in vitro interactions of citrate-coated AgNPs with porcine kidney (Pk15) cells. As uncertainty remains whether biological/cellular responses to AgNPs are solely as a result of the release of silver ions or whether the AgNPs themselves have toxic effects, we investigated the effects of Ag(+) on Pk15 cells for comparison. Next, we investigated the cellular uptake of both AgNPs and Ag(+) in Pk15 cells at various concentrations applied. The detected Ag contents in cells exposed to 50 mg l(-1) AgNPs and 50 mg l(-1) Ag(+) were 209 and 25 µg of Ag per 10(6) cells, respectively. Transmission electron microscopy (TEM) images indicated that the Pk15 cells internalized AgNPs by endocytosis. Both forms of silver, nano and ionic, decreased the number of viable Pk15 cells after 24 h in a dose-dependent manner. In spite of a significant uptake into the cells, AgNPs had only insignificant toxicity at concentrations lower than 25 mg l(-1) , whereas Ag(+) exhibited a significant decrease in cell viability at one-fifth of this concentration. The Comet assay suggested that a rather high concentration of AgNP (above 25 mg l(-1) ) is able to induce genotoxicity in Pk15 cells. Further studies must seek deeper understanding of AgNP behavior in biological media and their interactions with cellular membranes.

  14. Silver nanoparticle toxicity is related to coating materials and disruption of sodium concentration regulation.

    PubMed

    Kwok, Kevin W H; Dong, Wu; Marinakos, Stella M; Liu, Jie; Chilkoti, Ashutosh; Wiesner, Mark R; Chernick, Melissa; Hinton, David E

    2016-11-01

    Silver nanoparticles (AgNPs) have been increasingly commercialized and their release into the environment is imminent. Toxicity of AgNP has been studied with a wide spectrum of organisms, yet the mechanism of toxicity remains largely unknown. This study systematically compared toxicity of 10 AgNPs of different particle diameters and coatings to Japanese medaka (Oryzias latipes) larvae to understand how characteristics of AgNP relate to toxicity. Dissolution of AgNPs was largely dependent on particle size, but their aggregation behavior and toxicity were more dependent on coating materials. 96 h lethal concentration 50% (LC50) values correlated with AgNP aggregate size rather than size of individual nanoparticles. Of the AgNPs studied, the dissolved Ag concentration in the test suspensions did not account for all of the observed toxicity, indicating the role of NP-specific characteristics in resultant toxicity. Exposure to AgNP led to decrease of sodium concentration in the tissue and increased expression of Na(+)/K(+ )ATPase. Gene expression patterns also suggested that toxicity was related to disruption of sodium regulation and not to oxidative stress.

  15. How do physicochemical properties influence the toxicity of silver nanoparticles on freshwater decomposers of plant litter in streams?

    PubMed

    Batista, Daniela; Pascoal, Cláudia; Cássio, Fernanda

    2017-06-01

    AgNP physicochemical properties may affect AgNP toxicity, but their effects on plant litter decomposition and the species driving this key ecosystem process in freshwaters have been poorly investigated. We assessed the impacts of AgNPs with different size and surface coating (100nm PVP (polyvinylpyrrolidone)-dispersant, 50-60nm and 35nm uncoated) on freshwater decomposers of leaf litter by exposing leaf associated microbial assemblages to increasing concentrations of AgNPs (up to 200mgL(-1)) and of AgNO3 (up to 25mgL(-1)). We further conducted a feeding preference experiment with a common invertebrate shredder, Limnephilus sp., which was allowed to feed on microbially-colonized leaves previously exposed to AgNPs and AgNO3. Leaf decomposition and microbial activity and diversity were inhibited when exposed to increased concentrations of 100nm AgNPs (≥25mgL(-1)), while microbial activity was stimulated by exposure to 35nm AgNPs (≥100mgL(-1)). Invertebrate shredders preferred leaves exposed to 35nm AgNPs (25mgL(-1)) and avoided leaves exposed to AgNO3 (≥2mgL(-1)). Results from the characterization of AgNPs by dynamic light scattering revealed that AgNps with PVP-dispersant were more stable than the uncoated AgNPs. Our results highlight the importance of considering the physicochemical properties of NPs when assessing their toxicity to litter decomposers in freshwaters.

  16. Acute and subacute pulmonary toxicity caused by a single intratracheal instillation of colloidal silver nanoparticles in mice: pathobiological changes and metallothionein responses.

    PubMed

    Kaewamatawong, Theerayuth; Banlunara, Wijit; Maneewattanapinyo, Pattwat; Thammachareon, Chuchaat; Ekgasit, Sanong

    2014-01-01

    To study the acute and subacute pulmonary toxicity of colloidal silver nanoparticles (Ag-NPs), 0 or 100 ppm of Ag-NPs were instilled intratracheally in mice. Cellular and biochemical parameters in bronchoalveolar lavage fluid (BALF) and histological alterations were determined 1, 3, 7, 15, and 30 days after instillation. Ag-NPs induced moderate pulmonary inflammation and injury on BALF indices during the acute period; however, these changes gradually regressed in a time-dependent manner. Concomitant histopathological and laminin immunohistochemical findings generally correlated to BALF data. Superoxide dismutase and metallothionein expression occurred in particle-laden macrophages and alveolar epithelial cells, which correlated to lung lesions in mice treated with Ag-NPs. These findings suggest that instillation of Ag-NPs causes transient moderate acute lung inflammation and tissue damage. Oxidative stress may underlie the induction of injury to lung tissue. Moreover, the expression of metallothionein in tissues indicated the protective response to exposure to Ag-NPs.

  17. Accumulation dynamics and acute toxicity of silver nanoparticles to Daphnia magna and Lumbriculus variegatus: implications for metal modeling approaches.

    PubMed

    Khan, Farhan R; Paul, Kai B; Dybowska, Agnieszka D; Valsami-Jones, Eugenia; Lead, Jamie R; Stone, Vicki; Fernandes, Teresa F

    2015-04-07

    Frameworks commonly used in trace metal ecotoxicology (e.g., biotic ligand model (BLM) and tissue residue approach (TRA)) are based on the established link between uptake, accumulation and toxicity, but similar relationships remain unverified for metal-containing nanoparticles (NPs). The present study aimed to (i) characterize the bioaccumulation dynamics of PVP-, PEG-, and citrate-AgNPs, in comparison to dissolved Ag, in Daphnia magna and Lumbriculus variegatus; and (ii) investigate whether parameters of bioavailability and accumulation predict acute toxicity. In both species, uptake rate constants for AgNPs were ∼ 2-10 times less than for dissolved Ag and showed significant rank order concordance with acute toxicity. Ag elimination by L. variegatus fitted a 1-compartment loss model, whereas elimination in D. magna was biphasic. The latter showed consistency with studies that reported daphnids ingesting NPs, whereas L. variegatus biodynamic parameters indicated that uptake and efflux were primarily determined by the bioavailability of dissolved Ag released by the AgNPs. Thus, principles of BLM and TRA frameworks are confounded by the feeding behavior of D. magna where the ingestion of AgNPs perturbs the relationship between tissue concentrations and acute toxicity, but such approaches are applicable when accumulation and acute toxicity are linked to dissolved concentrations. The uptake rate constant, as a parameter of bioavailability inclusive of all available pathways, could be a successful predictor of acute toxicity.

  18. Pulmonary surfactant mitigates silver nanoparticle toxicity in human alveolar type-I-like epithelial cells.

    PubMed

    Sweeney, Sinbad; Leo, Bey Fen; Chen, Shu; Abraham-Thomas, Nisha; Thorley, Andrew J; Gow, Andrew; Schwander, Stephan; Zhang, Junfeng Jim; Shaffer, Milo S P; Chung, Kian Fan; Ryan, Mary P; Porter, Alexandra E; Tetley, Teresa D

    2016-09-01

    Accompanying increased commercial applications and production of silver nanomaterials is an increased probability of human exposure, with inhalation a key route. Nanomaterials that deposit in the pulmonary alveolar region following inhalation will interact firstly with pulmonary surfactant before they interact with the alveolar epithelium. It is therefore critical to understand the effects of human pulmonary surfactant when evaluating the inhalation toxicity of silver nanoparticles. In this study, we evaluated the toxicity of AgNPs on human alveolar type-I-like epithelial (TT1) cells in the absence and presence of Curosurf(®) (a natural pulmonary surfactant substitute), hypothesising that the pulmonary surfactant would act to modify toxicity. We demonstrated that 20nm citrate-capped AgNPs induce toxicity in human alveolar type I-like epithelial cells and, in agreement with our hypothesis, that pulmonary surfactant acts to mitigate this toxicity, possibly through reducing AgNP dissolution into cytotoxic Ag(+) ions. For example, IL-6 and IL-8 release by TT1 cells significantly increased 10.7- and 35-fold, respectively (P<0.01), 24h after treatment with 25μg/ml AgNPs. In contrast, following pre-incubation of AgNPs with Curosurf(®), this effect was almost completely abolished. We further determined that the mechanism of this toxicity is likely associated with Ag(+) ion release and lysosomal disruption, but not with increased reactive oxygen species generation. This study provides a critical understanding of the toxicity of AgNPs in target human alveolar type-I-like epithelial cells and the role of pulmonary surfactant in mitigating this toxicity. The observations reported have important implications for the manufacture and application of AgNPs, in particular for applications involving use of aerosolised AgNPs.

  19. In Vivo Quantitative Study of Sized-Dependent Transport and Toxicity of Single Silver Nanoparticles Using Zebrafish Embryos

    PubMed Central

    Lee, Kerry J.; Browning, Lauren M.; Nallathamby, Prakash D.; Desai, Tanvi; Cherukui, Pavan K.; Xu, Xiao-Hong Nancy

    2012-01-01

    Nanomaterials possess distinctive physicochemical properties (e.g., small sizes, high surface area-to-volume ratios) and promise a wide variety of applications, ranging from design of high quality consumer products to effective disease diagnosis and therapy. These properties can lead to toxic effects, potentially hindering advance in nanotechnology. In this study, we have synthesized and characterized purified and stable (non-aggregation) silver nanoparticles (Ag NPs, 41.6±9.1 nm in average diameters), and utilized early-developing (cleavage-stage) zebrafish embryos (critical aquatic and eco- species) as in vivo model organisms to probe diffusion and toxicity of Ag NPs. We found that single Ag NPs (30–72 nm diameters) passively diffused into the embryos through chorionic pores via random Brownian motion and stayed inside the embryos throughout their entire development (120 hours-post-fertilization, hpf). Dose and size dependent toxic effects of the NPs on embryonic development were observed, showing the possibility of tuning biocompatibility and toxicity of the NPs. At lower concentrations of the NPs (≤ 0.02 nM), 75–91% of embryos developed to normal zebrafish. At the higher concentrations of NPs (≥ 0.20 nM), 100% of embryos became dead. At the concentrations in between (0.02–0.2 nM), embryos developed to various deformed zebrafish. Number and sizes of individual Ag NPs embedded in tissues of normal and deformed zebrafish at 120 hpf were quantitatively analyzed, showing deformed zebrafish with higher number of larger NPs than normal zebrafish, and size-dependent nanotoxicity. By comparing with our previous studies of smaller Ag NPs (11.6±3.5 nm), the results further demonstrate striking size-dependent nanotoxicity that, at the same molar concentration, the larger Ag NPs (41.6±9.1 nm) are more toxic than the smaller Ag NPs (11.6±3.5 nm). PMID:22486336

  20. Oxidative Dissolution of Silver Nanoparticles by Chlorine: Implications to Silver Nanoparticle Fate and Toxicity.

    PubMed

    Garg, Shikha; Rong, Hongyan; Miller, Christopher J; Waite, T David

    2016-04-05

    The kinetics of oxidative dissolution of silver nanoparticles (AgNPs) by chlorine is investigated in this work, with results showing that AgNPs are oxidized in the presence of chlorine at a much faster rate than observed in the presence of dioxygen and/or hydrogen peroxide. The oxidation of AgNPs by chlorine occurs in air-saturated solution in stoichiometric amounts with 2 mol of AgNPs oxidized for each mole of chlorine added. Dioxygen plays an important role in OCl(-)-mediated AgNP oxidation, especially at lower OCl(-) concentrations, with the mechanism shifting from stoichiometric oxidation of AgNPs by OCl(-) in the presence of dioxygen to catalytic removal of OCl(-) by AgNPs in the absence of dioxygen. These results suggest that the presence of chlorine will mitigate AgNP toxicity by forming less-reactive AgCl(s) following AgNP oxidation, although the disinfection efficiency of OCl(-) may not be significantly impacted by the presence of AgNPs because a chlorine-containing species is formed on OCl(-) decay that has significant oxidizing capacity. Our results further suggest that the antibacterial efficacy of nanosilver particles embedded on fabrics may be negated when treated with detergents containing strong oxidants, such as chlorine.

  1. Highly selective and quantitative colorimetric detection of mercury(II) ions by carrageenan-functionalized Ag/AgCl nanoparticles.

    PubMed

    Narayanan, Kannan Badri; Han, Sung Soo

    2017-03-15

    The natural algal polysaccharide carrageenan was used for the greener synthesis of silver/silver chloride nanoparticles (Carr-Ag/AgCl NPs) without any toxic chemicals. We report the robust, highly selective, and sensitive colorimetric sensing of Hg(2+) ions using Carr-Ag/AgCl NPs without any further surface modification. The dark-brown color of a solution of Carr-Ag/AgCl NPs turned to white in a concentration-dependent manner with the addition of Hg(2+) ions, confirming the interaction of Carr-Ag/AgCl NPs with Hg(2+) ions. The plot of the extinction ratio of absorbance at 350nm to 450nm (A350/A450) for Carr-Ag/AgCl NPs against the concentration of [Hg(2+)] ions was linear, and the calibration curve was A350/A450=1.05254+0.00318×CHg with a lower detection limit of 1μM. This portable and cost-effective method for mercury(II) ion sensing is widely applicable in on-field qualitative and quantitative measurements of [Hg(2+)] ions in environmental or biological samples.

  2. Role of sulfide and ligand strength in controlling nanosilver toxicity.

    PubMed

    Choi, Okkyoung; Clevenger, Thomas E; Deng, Baolin; Surampalli, Rao Y; Ross, Louis; Hu, Zhiqiang

    2009-04-01

    Nanosilver has been used broadly in nanotechnology enhanced consumer products because of its strong antimicrobial properties. Silver nanoparticles (AgNPs) released from these products will likely enter wastewater collection and treatment systems. This research evaluated the role of sulfide and ligand strength in controlling nanosilver toxicity to nitrifying bacteria that are important in wastewater treatment. The nanosilver toxicity in the absence and presence of ligands (SO(4)(2-), S(2-), Cl(-), PO(4)(3-), and EDTA(-)) commonly present in wastewater was determined from the oxygen uptake rate measurements. Sulfide appeared to be the only ligand to effectively reduce nanosilver toxicity. By adding a small aliquot of sulfide that was stoichiometrically complexed with AgNPs, the nanosilver toxicity to nitrifying organisms was reduced by up to 80%. Scanning electron microscopy coupled with energy dispersive X-ray analysis indicated that AgNPs were highly reactive with sulfide to form new Ag(x)S(y) complexes or precipitates. These complexes were not oxidized after a prolonged period of aeration (18h). This information is useful for wastewater treatment design and operation to reduce nanosilver toxicity via sulfide complexation. While the biotic ligand model was successful in predicting the toxicity of Ag(+) ions, it could not accurately predict the toxicity of AgNPs. Nevertheless, it could be one of the many tools useful in predicting and controlling nanosilver toxicity to wastewater microorganisms.

  3. 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

  4. 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

    2017-03-30

    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.

  5. 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

  6. Negatively charged silver nanoparticles with potent antibacterial activity and reduced toxicity for pharmaceutical preparations

    PubMed Central

    Salvioni, Lucia; Galbiati, Elisabetta; Collico, Veronica; Alessio, Giulia; Avvakumova, Svetlana; Corsi, Fabio; Tortora, Paolo; Prosperi, Davide; Colombo, Miriam

    2017-01-01

    Background The discovery of new solutions with antibacterial activity as efficient and safe alternatives to common preservatives (such as parabens) and to combat emerging infections and drug-resistant bacterial pathogens is highly expected in cosmetics and pharmaceutics. Colloidal silver nanoparticles (NPs) are attracting interest as novel effective antimicrobial agents for the prevention of several infectious diseases. Methods Water-soluble, negatively charged silver nanoparticles (AgNPs) were synthesized by reduction with citric and tannic acid and characterized by transmission electron microscopy, dynamic light scattering, zeta potential, differential centrifuge sedimentation, and ultraviolet–visible spectroscopy. AgNPs were tested with model Gram-negative and Gram-positive bacteria in comparison to two different kinds of commercially available AgNPs. Results In this work, AgNPs with higher antibacterial activity compared to the commercially available colloidal silver solutions were prepared and investigated. Bacteria were plated and the antibacterial activity was tested at the same concentration of silver ions in all samples. The AgNPs did not show any significant reduction in the antibacterial activity for an acceptable time period. In addition, AgNPs were transferred to organic phase and retained their antibacterial efficacy in both aqueous and nonaqueous media and exhibited no toxicity in eukaryotic cells. Conclusion We developed AgNPs with a 20 nm diameter and negative zeta potential with powerful antibacterial activity and low toxicity compared to currently available colloidal silver, suitable for cosmetic preservatives and pharmaceutical preparations administrable to humans and/or animals as needed.

  7. Disentangling the effects of polymer coatings on silver nanoparticle agglomeration, dissolution, and toxicity to determine mechanisms of nanotoxicity

    NASA Astrophysics Data System (ADS)

    Zook, Justin M.; Halter, Melissa D.; Cleveland, Danielle; Long, Stephen E.

    2012-10-01

    Silver nanoparticles (AgNPs) are frequently coated with a variety of polymers, which may affect various interdependent mechanisms of toxicity or antimicrobial action, including agglomeration and dissolution rates. Here, we systematically measure how citrate, dextran, 5 and 20 kDa poly(ethylene glycol) (PEG), and poly(vinyl pyrrolidone) coatings affect AgNP agglomeration, dissolution, and toxicity. In addition, to disentangle the coatings' effects on agglomeration from their other effects, we produce multiple stable agglomerate sizes of several of the coated 23 nm AgNPs ranging from singly-dispersed to mean agglomerate sizes of several hundred nanometers. These dispersions allow us to independently study the effects of agglomeration and polymer coating on dissolution rate and hemolytic toxicity. We find that both hemolytic toxicity and dissolution rate are highest for the 5 kDa PEG coating, and toxicity and dissolution rate decrease significantly with increasing agglomerate size independent of coating. This correlation between toxicity and dissolution rate suggests that both polymer coating and agglomeration may affect hemolytic toxicity largely through their effects on dissolution. Because both the AgNP dissolution rate and hemolysis decrease only moderately compared to the large increases in agglomerate size, AgNPs' hemolytic toxicity may be caused by their large surface area and consequently high dissolution rate, rather than from other size-specific effects. At the silver concentrations used in this work, silver dissolved from AgNPs is expected to be primarily in the form of AgCl NPs, which are therefore more likely than Ag+ ions to be the primary drivers of hemolytic toxicity. In addition, all AgNPs we tested are much more toxic to horse red blood cells than sheep red blood cells, highlighting the complexity of toxic responses and the need to test toxicity in multiple biological systems.

  8. Non-toxic silver iodide (AgI) quantum dots sensitized solar cells

    SciTech Connect

    Moosakhani, S.; Sabbagh Alvani, A.A.; Sarabi, A.A.; Sameie, H.; Salimi, R.; Kiani, S.; Ebrahimi, Y.

    2014-12-15

    Highlights: • We have demonstrated AgI sensitized solar cell for the first time. • Obtained mesoporous titania powders possessed small crystallite size, high purity and surface area, and developed mesopores with a narrow pore size distribution. • Photovoltaic measurements revealed the electron injection from AgI to TiO{sub 2}. • The assembled AgI-QD solar cells yielded a power conversion efficiency of 0.64% under one sun illumination. • AgI may be a suitable candidate material for use as a non-toxic sensitizer in QDSSC. - Abstract: The present study reports the performance of a new photosensitizer -AgI quantum dots (QDs)- and mesoporous titania (TiO{sub 2}) nanocrystals synthesized by sol–gel (SG) method for solar cells. Furthermore, the effects of n-heptane on the textural properties of TiO{sub 2} nanocrystals were comprehensively investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N{sub 2} adsorption–desorption measurements, and UV–vis spectroscopy. TiO{sub 2} powders exhibited an anatase-type mesoporous structure with a high surface area of 89.7 m{sup 2}/g. Afterwards, the QDs were grown on mesoporous TiO{sub 2} surface to fabricate a TiO{sub 2}/AgI electrode by a successive ionic layer adsorption and reaction (SILAR) deposition route. Current–voltage characteristics and electrochemical impedance spectroscopy (EIS) data demonstrated that the injection of photoexcited electrons from AgI QDs into the TiO{sub 2} matrix produces photocurrents. The assembled AgI-QD solar cells yielded a power conversion efficiency of 0.64% and a short-circuit current of 2.13 mA/cm{sup 2} under one sun illumination.

  9. Developmental and reproductive toxicity of PVP/PEI-coated silver nanoparticles to zebrafish.

    PubMed

    Orbea, Amaia; González-Soto, Nagore; Lacave, José María; Barrio, Irantzu; Cajaraville, Miren P

    2017-03-05

    Cellular and molecular mechanisms of toxicity of silver nanoparticles (NPs) and their toxicity to fish embryos after waterborne exposure have been widely investigated, but much less information is available regarding the effect of Ag NPs on physiological functions such as growth or reproduction. In this work, the effects of waterborne exposure of adult zebrafish (Danio rerio) to PVP/PEI coated Ag NPs (~5nm) on reproduction (fecundity) were investigated. Moreover, the development of the embryos after parental exposure was compared with the development of embryos after direct waterborne exposure to the NPs. For this, two experiments were run: 1) embryos from unexposed parents were treated for 5days with Ag NPs (10μg Ag L(-1)-10mg Ag L(-1)) and development was monitored, and 2) selected breeding zebrafish were exposed for 3weeks to 100ng Ag L(-1) (environmentally relevant concentration) or to 10μg Ag L(-1) of Ag NPs, fecundity was scored and development of resulting embryos was monitored up to 5 d. Waterborne exposure of embryos to Ag NPs resulted highly toxic (LC50 at 120h=50μg Ag L(-1)), causing 100% mortality during the first 24h of exposure at 0.1mg Ag L(-1). Exposure of adults, even at the environmentally relevant silver concentration, caused a significant reduction of fecundity by the second week of treatment and resulting embryos showed a higher prevalence of malformations than control embryos. Exposed adult females presented higher prevalence of vacuolization in the liver. These results show that Ag NPs at an environmentally relevant concentration are able to affect population level parameters in zebrafish.

  10. 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

  11. Capillary electrophoresis with online stacking in combination with AgNPs@MCM-41 reinforced hollow fiber solid-liquid phase microextraction for quantitative analysis of Capecitabine and its main metabolite 5-Fluorouracil in plasma samples isolated from cancer patients.

    PubMed

    Forough, Mehrdad; Farhadi, Khalil; Molaei, Rahim; Khalili, Hedayat; Shakeri, Ramin; Zamani, Asghar; Matin, Amir Abbas

    2017-01-01

    The purpose of this study is the development and validation of a simple, novel, selective and fast off-line microextraction technique combining capillary electrophoresis with in-column field-amplified sample injection (FASI) for the simultaneous determination of capecitabine (CAP) and its active metabolite, 5-Fluorouracil (5-FU), in human plasma. At the moment, there is a lack of using cost-effective CE tool combined with novel miniaturized sample clean-up techniques for analysis of these important anti-cancer agents in plasma samples. This paper intends to fill this gap and describe a simple off-line sample pretreatment by means of AgNPs@MCM-41 reinforced hollow fiber Solid/Liquid phase microextraction (AgNPs@MCM41-HF-SLPME) with subsequent quantitation by FASI-CE. The separation of analytes was performed using a BGE containing 60mM phosphate-Tris buffer (pH 7) with 10% methanol as an organic modifier. Before sample loading, a short water plug (50mbar, 3s) was injected to permit FASI for stacking. Various parameters affecting the off-line microextraction efficiency as well as FASI were optimized. Migration time was found to be 6.6 (±0.1)min for 5-FU and 7.4 (±0.2)min for CAP. The linearity, precision, accuracy, recovery, selectivity, specificity, stability as well as the robustness of the method was evaluated from spiked plasma samples during the course of validation. The results revealed that the presented technique demonstrates acceptable accuracy and precision, miniaturized sample preparation and a reduced need for complicated equipment along with an acceptable analysis time. The validated method was successfully applied to determine CAP and 5-FU in patient's plasma samples.

  12. Biosynthesis of silver nanoparticles using a probiotic Bacillus licheniformis Dahb1 and their antibiofilm activity and toxicity effects in Ceriodaphnia cornuta.

    PubMed

    Shanthi, Sathappan; Jayaseelan, Barbanas David; Velusamy, Palaniyandi; Vijayakumar, Sekar; Chih, Cheng Ta; Vaseeharan, Baskaralingam

    2016-04-01

    In the present study, we synthesized and characterized a probiotic Bacillus licheniformis cell free extract (BLCFE) coated silver nanoparticles (BLCFE-AgNPs). These BLCFE-AgNPs were characterized by UV-visible spectrophotometer, XRD, EDX, FTIR, TEM and AFM. A strong surface plasmon resonance centered at 422 nm in UV-visible spectrum indicates the formation of AgNPs. The XRD spectrum of silver nanoparticles exhibited 2θ values corresponding to the silver nanocrystal. TEM and AFM showed the AgNPs were spherical in shape within the range of 18.69-63.42 nm and the presence of silver was confirmed by EDX analysis. Light and Confocal Laser Scanning Microscope (CLSM) images showed a weak adherence and disintegrated biofilm formation of Vibrio parahaemolyticus Dav1 treated with BLCFE-AgNPs compared to control. This result suggests that BLCFE-AgNps may be used for the control of biofilm forming bacterial populations in the biomedical field. In addition, acute toxicity results concluded that BLCFE-AgNPs were less toxic to the fresh water crustacean Ceriodaphnia cornuta (50 μg/ml) when compared to AgNO3 (22 μg/ml). This study also reports a short term analysis (24 h) of uptake and depuration of BLCFE-AgNPs in C. cornuta.

  13. Humic substances alleviate the aquatic toxicity of polyvinylpyrrolidone-coated silver nanoparticles to organisms of different trophic levels.

    PubMed

    Wang, Zhuang; Quik, Joris T K; Song, Lan; Van Den Brandhof, Evert-Jan; Wouterse, Marja; Peijnenburg, Willie J G M

    2015-06-01

    The present study investigated how humic substances (HS) modify the aquatic toxicity of silver nanoparticles (AgNPs) as these particles agglomerate in water and interact with HS. An alga species (Raphidocelis subcapitata), a cladoceran species (Chydorus sphaericus), and a freshwater fish larva (Danio rerio), representing organisms of different trophic levels, were exposed to colloids of the polyvinylpyrrolidone-coated AgNPs in the presence and absence of HS. Results show that the presence of HS alleviated the aquatic toxicity of the AgNP colloids to all the organisms in a dose-dependent manner. The particle size distribution of the AgNPs' colloidal particles shifted to lower values due to the presence of HS, implying that the decrease in the toxicity of the AgNP colloids cannot be explained by the variation of agglomeration size. The surface charge of the AgNPs was found to be more negative in the presence of high concentrations of HS, suggesting an electrostatic barrier by which HS might limit interactions between particles and algae cells; indeed, this effect reduced the algae toxicity. Observations on silver ions (Ag(+)) release show that HS inhibit AgNP dissolution, depending on the concentrations of HS. When toxic effects were expressed as a function of each Ag-species, toxicity of the free Ag(+) was found to be much higher than that of the agglomerated particles.

  14. The Molecular Mechanisms of the Antibacterial Effect of Picosecond Laser Generated Silver Nanoparticles and Their Toxicity to Human Cells.

    PubMed

    Korshed, Peri; Li, Lin; Liu, Zhu; Wang, Tao

    2016-01-01

    Silver nanoparticles (Ag NPs) are known to have antibacterial properties. They are commonly produced by chemical synthesis which involves the use of harmful reducing agents. Contras, the laser technique is able to generate high-purity Ag NPs in water with specified surface charge characteristics. In the past, the molecular mechanisms contributing to the bactericidal effects of Ag NPs have been investigated extensively, but little is known of the antibacterial and toxic effects and mechanisms involved in laser-generated Ag NPs. In the current study Ag NPs were generated by picosecond laser ablation. Their antibacterial activity was determined on the gram-negative bacteria E. coli and Pseudomonas aeruginosa, and the gram positive bacteria Staphylococcus aureus including the methicillin resistant strain MRSA. Results showed that the laser generated Ag NPs exhibited strong dose-dependent antibacterial activity against all the three bacterial strains tested. Using E.coli as a model system, the laser Ag NPs treatment induced significantly high levels of reactive oxygen species (ROS). These ROS did not include detectable hydroxyl radicals, suggesting for the first time the selective ROS induction in bacterial cells by laser generated Ag NPs. The increased ROS was accompanied by significantly reduced cellular glutathione, and increased lipid peroxidation and permeability, suggesting ROS related bacterial cell damage. The laser generated Ag NPs exhibited low toxicity (within 72 hours) to five types of human cells although a weak significant decrease in cell survival was observed for endothelial cells and the lung cells. We conclude that picosecond laser generated Ag NPs have a broad spectrum of antibacterial effects against microbes including MRSA with minimal human cell toxicity. The oxidative stress is likely the key mechanism underlying the bactericidal effect, which leads to lipid peroxidation, depletion of glutathione, DNA damages and eventual disintegration of the

  15. The Molecular Mechanisms of the Antibacterial Effect of Picosecond Laser Generated Silver Nanoparticles and Their Toxicity to Human Cells

    PubMed Central

    Korshed, Peri; Li, Lin; Liu, Zhu; Wang, Tao

    2016-01-01

    Silver nanoparticles (Ag NPs) are known to have antibacterial properties. They are commonly produced by chemical synthesis which involves the use of harmful reducing agents. Contras, the laser technique is able to generate high-purity Ag NPs in water with specified surface charge characteristics. In the past, the molecular mechanisms contributing to the bactericidal effects of Ag NPs have been investigated extensively, but little is known of the antibacterial and toxic effects and mechanisms involved in laser-generated Ag NPs. In the current study Ag NPs were generated by picosecond laser ablation. Their antibacterial activity was determined on the gram-negative bacteria E. coli and Pseudomonas aeruginosa, and the gram positive bacteria Staphylococcus aureus including the methicillin resistant strain MRSA. Results showed that the laser generated Ag NPs exhibited strong dose-dependent antibacterial activity against all the three bacterial strains tested. Using E.coli as a model system, the laser Ag NPs treatment induced significantly high levels of reactive oxygen species (ROS). These ROS did not include detectable hydroxyl radicals, suggesting for the first time the selective ROS induction in bacterial cells by laser generated Ag NPs. The increased ROS was accompanied by significantly reduced cellular glutathione, and increased lipid peroxidation and permeability, suggesting ROS related bacterial cell damage. The laser generated Ag NPs exhibited low toxicity (within 72 hours) to five types of human cells although a weak significant decrease in cell survival was observed for endothelial cells and the lung cells. We conclude that picosecond laser generated Ag NPs have a broad spectrum of antibacterial effects against microbes including MRSA with minimal human cell toxicity. The oxidative stress is likely the key mechanism underlying the bactericidal effect, which leads to lipid peroxidation, depletion of glutathione, DNA damages and eventual disintegration of the

  16. Hypoxia inducible factor-1 (HIF-1)–flavin containing monooxygenase-2 (FMO-2) signaling acts in silver nanoparticles and silver ion toxicity in the nematode, Caenorhabditis elegans

    SciTech Connect

    Eom, Hyun-Jeong; Ahn, Jeong-Min; Kim, Younghun; Choi, Jinhee

    2013-07-15

    In the present study, nanotoxicity mechanism associated with silver nanoparticles (AgNPs) exposure was investigated on the nematode, Caenorhabditis elegans focusing on the hypoxia response pathway. In order to test whether AgNPs-induced hypoxia inducible factor-1 (HIF-1) activation was due to hypoxia or to oxidative stress, depletion of dissolved oxygen (DO) in the test media and a rescue effect using an antioxidant were investigated, respectively. The results suggested that oxidative stress was involved in activation of the HIF-1 pathway. We then investigated the toxicological implications of HIF-1 activation by examining the HIF-1 mediated transcriptional response. Of the genes tested, increased expression of the flavin containing monooxygenase-2 (FMO-2) gene was found to be the most significant as induced by AgNPs exposure. We found that AgNPs exposure induced FMO-2 activation in a HIF-1 and p38 MAPK PMK-1 dependent manner, and oxidative stress was involved in it. We conducted all experiments to include comparison of AgNPs and AgNO{sub 3} in order to evaluate whether any observed toxicity was due to dissolution or particle specific. The AgNPs and AgNO{sub 3} did not produce any qualitative differences in terms of exerting toxicity in the pathways observed in this study, however, considering equal amount of silver mass, in every endpoint tested the AgNPs were found to be more toxic than AgNO{sub 3}. These results suggest that Ag nanotoxicity is dependent not only on dissolution of Ag ion but also on particle specific effects and HIF-1–FMO-2 pathway seems to be involved in it. - Highlights: • HIF-1 signaling was investigated in C. elegans exposed to AgNPs and AgNO{sub 3}. • HIF-1 and PMK-1 were needed for AgNPs- and AgNO{sub 3}-induced fmo-2 gene expression. • PMK-1–HIF-1–FMO-2 pathway was dependent on oxidative stress. • AgNPs and AgNO{sub 3} did not produce any qualitative differences in HIF-1 signaling. • AgNPs were more toxic than an equal

  17. Toxicity Testing of Pristine and Aged Silver Nanoparticles in Real Wastewaters Using Bioluminescent Pseudomonas putida

    PubMed Central

    Mallevre, Florian; Alba, Camille; Milne, Craig; Gillespie, Simon; Fernandes, Teresa F.; Aspray, Thomas J.

    2016-01-01

    Impact of aging on nanoparticle toxicity in real matrices is scarcely investigated due to a lack of suitable methodologies. Herein, the toxicity of pristine and aged silver nanoparticles (Ag NPs) to a bioluminescent Pseudomonas putida bioreporter was measured in spiked crude and final wastewater samples (CWs and FWs, respectively) collected from four wastewater treatment plants (WWTPs). Results showed lower toxicity of pristine Ag NPs in CWs than in FWs. The effect of the matrix on the eventual Ag NP toxicity was related to multiple physico-chemical parameters (biological oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) pH, ammonia, sulfide and chloride) based on a multivariate analysis. However, no collection site effect was concluded. Aged Ag NPs (up to eight weeks) were found less toxic than pristine Ag NPs in CWs; evident increased aggregation and decreased dissolution were associated with aging. However, Ag NPs exhibited consistent toxicity in FWs despite aging; comparable results were obtained in artificial wastewater (AW) simulating effluent. The study demonstrates the potency of performing nanoparticle acute toxicity testing in real and complex matrices such as wastewaters using relevant bacterial bioreporters. PMID:28344306

  18. Silver toxicity across salinity gradients: the role of dissolved silver chloride species (AgCl x ) in Atlantic killifish (Fundulus heteroclitus) and medaka (Oryzias latipes) early life-stage toxicity.

    PubMed

    Matson, Cole W; Bone, Audrey J; Auffan, Mélanie; Lindberg, T Ty; Arnold, Mariah C; Hsu-Kim, Heileen; Wiesner, Mark R; Di Giulio, Richard T

    2016-08-01

    The influence of salinity on Ag toxicity was investigated in Atlantic killifish (Fundulus heteroclitus) early life-stages. Embryo mortality was significantly reduced as salinity increased and Ag(+) was converted to AgCl(solid). However, as salinity continued to rise (>5 ‰), toxicity increased to a level at least as high as observed for Ag(+) in deionized water. Rather than correlating with Ag(+), Fundulus embryo toxicity was better explained (R(2) = 0.96) by total dissolved Ag (Ag(+), AgCl2 (-), AgCl3 (2-), AgCl4 (3-)). Complementary experiments were conducted with medaka (Oryzias latipes) embryos to determine if this pattern was consistent among evolutionarily divergent euryhaline species. Contrary to Fundulus data, medaka toxicity data were best explained by Ag(+) concentrations (R(2) = 0.94), suggesting that differing ionoregulatory physiology may drive observed differences. Fundulus larvae were also tested, and toxicity did increase at higher salinities, but did not track predicted silver speciation. Alternatively, toxicity began to increase only at salinities above the isosmotic point, suggesting that shifts in osmoregulatory strategy at higher salinities might be an important factor. Na(+) dysregulation was confirmed as the mechanism of toxicity in Ag-exposed Fundulus larvae at both low and high salinities. While Ag uptake was highest at low salinities for both Fundulus embryos and larvae, uptake was not predictive of toxicity.

  19. Blood Clearance, Distribution, Transformation, Excretion, and Toxicity of Near-Infrared Quantum Dots Ag2Se in Mice.

    PubMed

    Tang, Huan; Yang, Sheng-Tao; Yang, Yi-Fan; Ke, Da-Ming; Liu, Jia-Hui; Chen, Xing; Wang, Haifang; Liu, Yuanfang

    2016-07-20

    As a novel fluorescent probe in the second near-infrared window, Ag2Se quantum dots (QDs) exhibit great prospect in in vivo imaging due to their maximal penetration depth and negligible background. However, the in vivo behavior and toxicity of Ag2Se QDs still largely remain unknown, which severely hinders their wide-ranging biomedical applications. Herein, we systematically studied the blood clearance, distribution, transformation, excretion, and toxicity of polyethylene glycol (PEG) coated Ag2Se QDs in mice after intravenous administration with a high dose of 8 μmol/kg body weight. QDs are quickly cleared from the blood with a circulation half-life of 0.4 h. QDs mainly accumulate in liver and spleen and are remarkably transformed into Ag and Se within 1 week. Ag is excreted from the body readily through both feces and urine, whereas Se is excreted hardly. The toxicological evaluations demonstrate that there is no overt acute toxicity of Ag2Se QDs to mice. Moreover, in regard to the in vivo stability problem of Ag2Se QDs, the biotransformation and its related metabolism are intensively discussed, and some promising coating means for Ag2Se QDs to avert transformation are proposed as well. Our work lays a solid foundation for safe applications of Ag2Se QDs in bioimaging in the future.

  20. Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

    NASA Astrophysics Data System (ADS)

    Liu, Pengpeng; Guan, Rongfa; Ye, Xingqian; Jiang, Jiaxin; Liu, Mingqi; Huang, Guangrong; Chen, Xiaoting

    2011-07-01

    Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL-1. LDH leakage significantly increased in cells exposed to Ag NPs (>= 25 μg mL-1) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL-1). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

  1. Qualitative toxicity assessment of silver nanoparticles on the fresh water bacterial isolates and consortium at low level of exposure concentration.

    PubMed

    Kumar, Deepak; Kumari, Jyoti; Pakrashi, Sunandan; Dalai, Swayamprava; Raichur, Ashok M; Sastry, T P; Mandal, A B; Chandrasekaran, N; Mukherjee, Amitava

    2014-10-01

    Silver nanoparticles (AgNPs) pose a high risk of exposure to the natural environment owing to their extensive usage in various consumer products. In the present study we attempted to understand the harmful effect of AgNPs at environmentally relevant low concentration levels (≤1ppm) towards two different freshwater bacterial isolates and their consortium. The standard plate count assay suggested that the AgNPs were toxic towards the fresh water bacterial isolates as well as the consortium, though toxicity was significantly reduced for the cells in the consortium. The oxidative stress assessment and membrane permeability studies corroborated with the toxicity data. The detailed electron microscopic studies suggested the cell degrading potential of the AgNPs, and the FT-IR studies confirmed the involvement of the surface groups in the toxic effects. No significant ion leaching from the AgNPs was observed at the applied concentration levels signifying the dominant role of the particle size, and size distribution in bacterial toxicity. The reduced toxicity for the cells in the consortium than the individual isolates has major significance in further studies on the ecotoxicity of the AgNPs.

  2. Properties of silver nanoparticles influencing their uptake in and toxicity to the earthworm Lumbricus rubellus following exposure in soil.

    PubMed

    Makama, Sunday; Piella, Jordi; Undas, Anna; Dimmers, Wim J; Peters, Ruud; Puntes, Victor F; van den Brink, Nico W

    2016-11-01

    Physicochemical properties of nanoparticles influence their environmental fate and toxicity, and studies investigating this are vital for a holistic approach towards a comprehensive and adequate environmental risk assessment. In this study, we investigated the effects of size, surface coating (charge) of silver nanoparticles (AgNPs) - a most commonly-used nanoparticle-type, on the bioaccumulation in, and toxicity (survival, growth, cocoon production) to the earthworm Lumbricus rubellus. AgNPs were synthesized in three sizes: 20, 35 and 50 nm. Surface-coating with bovine serum albumin (AgNP_BSA), chitosan (AgNP_Chit), or polyvinylpyrrolidone (AgNP_PVP) produced negative, positive and neutral particles respectively. In a 28-day sub-chronic reproduction toxicity test, earthworms were exposed to these AgNPs in soil (0-250 mg Ag/kg soil DW). Earthworms were also exposed to AgNO3 at concentrations below known EC50. Total Ag tissue concentration indicated uptake by earthworms was generally highest for the AgNP_BSA especially at the lower exposure concentration ranges, and seems to reach a plateau level between 50 and 100 mg Ag/kg soil DW. Reproduction was impaired at high concentrations of all AgNPs tested, with AgNP_BSA particles being the most toxic. The EC50 for the 20 nm AgNP_BSA was 66.8 mg Ag/kg soil, with exposure to <60 mg Ag/kg soil already showing a decrease in the cocoon production. Thus, based on reproductive toxicity, the particles ranked: AgNP_BSA (negative) > AgNP_PVP (neutral) > Chitosan (positive). Size had an influence on uptake and toxicity of the AgNP_PVP, but not for AgNP_BSA nor AgNP_Chit. This study provides essential information on the role of physicochemical properties of AgNPs in influencing uptake by a terrestrial organism L. rubellus under environmentally relevant conditions. It also provides evidence of the influence of surface coating (charge) and the limited effect of size in the range of 20-50 nm, in driving uptake and toxicity

  3. Size-dependent cytotoxicity of silver nanoparticles in human lung cells: the role of cellular uptake, agglomeration and Ag release

    PubMed Central

    2014-01-01

    Background Silver nanoparticles (AgNPs) are currently one of the most manufactured nanomaterials. A wide range of toxicity studies have been performed on various AgNPs, but these studies report a high variation in toxicity and often lack proper particle characterization. The aim of this study was to investigate size- and coating-dependent toxicity of thoroughly characterized AgNPs following exposure of human lung cells and to explore the mechanisms of toxicity. Methods BEAS-2B cells were exposed to citrate coated AgNPs of different primary particle sizes (10, 40 and 75 nm) as well as to 10 nm PVP coated and 50 nm uncoated AgNPs. The particle agglomeration in cell medium was investigated by photon cross correlation spectroscopy (PCCS); cell viability by LDH and Alamar Blue assay; ROS induction by DCFH-DA assay; genotoxicity by alkaline comet assay and γH2AX foci formation; uptake and intracellular localization by transmission electron microscopy (TEM); and cellular dose as well as Ag release by atomic absorption spectroscopy (AAS). Results The results showed cytotoxicity only of the 10 nm particles independent of surface coating. In contrast, all AgNPs tested caused an increase in overall DNA damage after 24 h assessed by the comet assay, suggesting independent mechanisms for cytotoxicity and DNA damage. However, there was no γH2AX foci formation and no increased production of intracellular reactive oxygen species (ROS). The reasons for the higher toxicity of the 10 nm particles were explored by investigating particle agglomeration in cell medium, cellular uptake, intracellular localization and Ag release. Despite different agglomeration patterns, there was no evident difference in the uptake or intracellular localization of the citrate and PVP coated AgNPs. However, the 10 nm particles released significantly more Ag compared with all other AgNPs (approx. 24 wt% vs. 4–7 wt%) following 24 h in cell medium. The released fraction in cell medium did not induce any

  4. Sub-chronic Dermal Toxicity of Silver Nanoparticles in Guinea Pig: Special Emphasis to Heart, Bone and Kidney Toxicities.

    PubMed

    Korani, Mitra; Rezayat, Seyed Mahdi; Arbabi Bidgoli, Sepideh

    2013-01-01

    Silver nanoparticles (Ag NPs) have been widely used as new potent antimicrobial agents in cosmetic and hygienic products. Present study compares the tissue levels of Ag NPs in different organs of Guiana Pigs quantitatively after dermal application and analysis the morphological changes and pathological abnormalities on the basis of the Ag NPs tissue levels. Before toxicological assessments,the size of colloidal nanosilver was recorded by X-Ray Diffraction and Transmission Electron Microscope tests and the sizes of samples were recorded in sizes less than 100 nm. For toxicological evaluation, male guinea pigs were exposed to three concentrations of Ag NPs (100, 1000 and 10000 ppm) according to acute pretests for further assessments in subchronic model in a period of 13 weeks . A close correlation between dermal exposure and tissue levels of Ag NPs was found (p < 0.05) and tissue uptakes happened in dose dependent manner with the following ranking: ki dney>muscle>bone>skin>liver>heart >spleen. In histopathological studies, severe proximal convoluted tubule degeneration and distal convoluted tubule were seen in the kidneys of the middle and high-dose animals. Separated lines and marrow space narrow were determined as two major signs of bone toxicities which observed in three different dose levels of Ag NPs. Increased dermal dose of Ag NPs caused cardiocyte deformity, congestion and inflammation. The three different Ag NPs concentration gave comparable results for several endpoints measured in heart, bone and kidney, but differed in tissue concentrations and the extent of histopathological changes. It seems that Ag ions could be detected in different organs after dermal exposure ,which has the potential to provide target organ toxicities in a time and dose dependent manner.

  5. Influence of ammonia on silver nanoparticle dissolution and toxicity to Nitrosomonas europaea.

    PubMed

    Kostigen Mumper, Cameron; Ostermeyer, Ann-Kathrin; Semprini, Lewis; Radniecki, Tyler S

    2013-11-01

    Nitrosomonas europaea, a model ammonia oxidizing bacterium, was sensitive to both ionic silver (Ag(+)) and 20 nm citrate capped silver nanoparticles (AgNPs). AgNP toxicity has been previously shown to be primarily due to the dissolution of Ag(+). The rate of AgNP dissolution dramatically increased in test medium containing ammonium sulfate ((NH4)2SO4) and HEPES buffer compared to test medium containing either deionized water or HEPES buffer alone. The AgNP dissolution rates accelerated with increases in ammonia (NH3) concentrations either through increases in pH or through higher (NH4)2SO4 concentrations. Ammonia likely participated in the oxidation of the AgNP to form [Formula: see text] in solution leading to the observed increase in AgNP dissolution rates. AgNP toxicity was enhanced as NH3 concentrations increased. However, Ag(+) toxicity was constant at all NH3 concentrations tested. Therefore, it can be concluded that the increased AgNP toxicity was due to increased Ag(+) release and not due to a synergistic effect between NH3 and Ag(+). The results of this study may provide insights in the fate and toxicity of AgNPs in high NH3 environments including wastewater treatment plants, eutrophic waterways and alkaline environments.

  6. Effects of chloride and ionic strength on physical morphology, dissolution, and bacterial toxicity of silver nanoparticles.

    PubMed

    Chambers, Bryant A; Afrooz, A R M Nabiul; Bae, Sungwoo; Aich, Nirupam; Katz, Lynn; Saleh, Navid B; Kirisits, Mary Jo

    2014-01-01

    In this study, we comprehensively evaluate chloride- and ionic-strength-mediated changes in the physical morphology, dissolution, and bacterial toxicity of silver nanoparticles (AgNPs), which are one of the most-used nanomaterials. The findings isolate the impact of ionic strength from that of chloride concentration. As ionic strength increases, AgNP aggregation likewise increases (such that the hydrodynamic radius [HR] increases), fractal dimension (Df) strongly decreases (providing increased available surface relative to suspensions with higher Df), and the release of Ag(aq) increases. With increased Ag(+) in solution, Escherichia coli demonstrates reduced tolerance to AgNP exposure (i.e., toxicity increases) under higher ionic strength conditions. As chloride concentration increases, aggregates are formed (HR increases) but are dominated by AgCl(0)(s) bridging of AgNPs; relatedly, Df increases. Furthermore, AgNP dissolution strongly increases under increased chloride conditions, but the dominant, theoretical, equilibrium aqueous silver species shift to negatively charged AgClx((x-1)-) species, which appear to be less toxic to E. coli. Thus, E. coli demonstrates increased tolerance to AgNP exposure under higher chloride conditions (i.e., toxicity decreases). Expression measurements of katE, a gene involved in catalase production to alleviate oxidative stress, support oxidative stress in E. coli as a result of Ag(+) exposure. Overall, our work indicates that the environmental impacts of AgNPs must be evaluated under relevant water chemistry conditions.

  7. 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.

  8. Sulfidation of silver nanoparticles: natural antidote to their toxicity.

    PubMed

    Levard, Clement; Hotze, Ernest M; Colman, Benjamin P; Dale, Amy L; Truong, Lisa; Yang, X Y; Bone, Audrey J; Brown, Gordon E; Tanguay, Robert L; Di Giulio, Richard T; Bernhardt, Emily S; Meyer, Joel N; Wiesner, Mark R; Lowry, Gregory V

    2013-01-01

    Nanomaterials are highly dynamic in biological and environmental media. A critical need for advancing environmental health and safety research for nanomaterials is to identify physical and chemical transformations that affect the nanomaterial properties and their toxicity. Silver nanoparticles, one of the most toxic and well-studied nanomaterials, readily react with sulfide to form Ag(0)/Ag2S core-shell particles. Here, we show that sulfidation decreased silver nanoparticle toxicity to four diverse types of aquatic and terrestrial eukaryotic organisms (Danio rerio (zebrafish), Fundulus heteroclitus (killifish), Caenorhabditis elegans (nematode worm), and the aquatic plant Lemna minuta (least duckweed)). Toxicity reduction, which was dramatic in killifish and duckweed even for low extents of sulfidation (about 2 mol % S), is primarily associated with a decrease in Ag(+) concentration after sulfidation due to the lower solubility of Ag2S relative to elemental Ag (Ag(0)). These results suggest that even partial sulfidation of AgNP will decrease the toxicity of AgNPs relative to their pristine counterparts. We also show that, for a given organism, the presence of chloride in the exposure media strongly affects the toxicity results by affecting Ag speciation. These results highlight the need to consider environmental transformations of NPs in assessing their toxicity to accurately portray their potential environmental risks.

  9. Sodium cholate-templated blue light-emitting Ag subnanoclusters: in vivo toxicity and imaging in zebrafish embryos.

    PubMed

    Chandirasekar, Shanmugam; Chandrasekaran, Chandramouli; Muthukumarasamyvel, Thangavel; Sudhandiran, Ganapasam; Rajendiran, Nagappan

    2015-01-28

    We report a novel green chemical approach for the synthesis of blue light-emitting and water-soluble Ag subnanoclusters, using sodium cholate (NaC) as a template at a concentration higher than the critical micelle concentration (CMC) at room temperature. However, under photochemical irradiation, small anisotropic and spherically shaped Ag nanoparticles (3-11 nm) were obtained upon changing the concentration of NaC from below to above the CMC. The matrix-assisted laser desorption ionization time-of-flight and electrospray ionization mass spectra showed that the cluster sample was composed of Ag4 and Ag6. The optical properties of the clusters were studied by UV-visible and luminescence spectroscopy. The lifetime of the synthesized fluorescent Ag nanoclusters (AgNCs) was measured using a time-correlated single-photon counting technique. High-resolution transmission electron microscopy was used to assess the size of clusters and nanoparticles. A protocol for transferring nanoclusters to organic solvents is also described. Toxicity and bioimaging studies of NaC templated AgNCs were conducted using developmental stage zebrafish embryos. From the survival and hatching experiment, no significant toxic effect was observed at AgNC concentrations of up to 200 μL/mL, and the NC-stained embryos exhibited blue fluorescence with high intensity for a long period of time, which shows that AgNCs are more stable in living system.

  10. Toxicity effect of silver nanoparticles in brine shrimp Artemia.

    PubMed

    Arulvasu, Chinnasamy; Jennifer, Samou Michael; Prabhu, Durai; Chandhirasekar, Devakumar

    2014-01-01

    The present study revealed the toxic effect of silver nanoparticles (AgNPs) in Artemia nauplii and evaluated the mortality rate, hatching percentage, and genotoxic effect in Artemia nauplii/cysts. The AgNPs were commercially purchased and characterized using field emission scanning electron microscope with energy dispersive X-ray spectroscopy. Nanoparticles were spherical in nature and with size range of 30-40 nm. Artemia cysts were collected from salt pan, processed, and hatched in sea water. Artemia nauplii (II instar) were treated using silver nanoparticles of various nanomolar concentrations and LC50 value (10 nM) and mortality rate (24 and 48 hours) was evaluated. Hatching percentage of decapsulated cysts treated with AgNPs was examined. Aggregation of AgNPs in the gut region of nauplii was studied using phase contrast microscope and apoptotic cells in nauplii stained with acridine orange were observed using fluorescence microscope. DNA damage of single cell of nauplii was determined by comet assay. This study showed that as the concentration of AgNPs increased, the mortality rate, aggregation in gut region, apoptotic cells, and DNA damage increased in nauplii, whereas the percentage of hatching in Artemia cysts decreased. Thus this study revealed that the nanomolar concentrations of AgNPs have toxic effect on both Artemia nauplii and cysts.

  11. Different behavior of Staphylococcus epidermidis in intracellular biosynthesis of silver and cadmium sulfide nanoparticles: more stability and lower toxicity of extracted nanoparticles.

    PubMed

    Rezvani Amin, Zohreh; Khashyarmanesh, Zahra; Fazly Bazzaz, Bibi Sedigheh

    2016-09-01

    Chemical reagents that are used for synthesis of nanoparticles are often toxic, while biological reagents are safer and cost-effective. Here, the behavior of Staphylococcus epidermidis (ATCC 12228) was evaluated for biosynthesis of silver nanoparticles (Ag-NPs) and cadmium sulfide nanoparticles (CdS-NPs) using TEM images intra- and extracellularly. The bacteria only biosynthesized the nanoparticles intracellularly and distributed Ag-NPs throughout the cytoplasm and on outside surface of cell walls, while CdS-NPs only formed in cytoplasm near the cell wall. A new method for purification of the nanoparticles was used. TEM images of pure CdS-NPs confirmed biosynthesis of agglomerated nanoparticles. Biosynthetic Ag-NPs were more stable against bright light and aggregation reaction than synthetic Ag-NPs (prepared chemically) also biosynthetic Ag-NPs displayed lower toxicity in in vitro assays. CdS-NPs indicated no toxicity in in vitro assays. Biosynthetic nanoparticles as product of the detoxification pathway may be safer and more stable for biosensors.

  12. Silver nanoparticle toxicity effect on growth and cellular viability of the aquatic plant Lemna gibba.

    PubMed

    Oukarroum, Abdallah; Barhoumi, Lotfi; Pirastru, Laura; Dewez, David

    2013-04-01

    The toxicity effect of silver nanoparticles (AgNPs) on growth and cellular viability was investigated on the aquatic plant Lemna gibba exposed over 7 d to 0, 0.01, 0.1, 1, and 10 mg/L of AgNPs. Growth inhibition was demonstrated by a significant decrease of frond numbers dependent on AgNP concentration. Under these conditions, reduction in plant cellular viability was detected for 0.1, 1, and 10 mg/L of AgNPs within 7 d of AgNPs treatment. This effect was highly correlated with the production of intracellular reactive oxygen species (ROS). A significant increase of intracellular ROS formation was triggered by 1 and 10 mg/L of AgNP exposure. The induced oxidative stress was related to Ag accumulation within L. gibba plant cells and with the increasing concentration of AgNP exposure in the medium. The authors' results clearly suggested that AgNP suspension represented a potential source of toxicity for L. gibba plant cells. Due to the low release capacity of free soluble Ag from AgNP dissolution in the medium, it is most likely that the intracellular uptake of Ag was directly from AgNPs, triggering cellular oxidative stress that may be due to the release of free Ag inside plant cells. Therefore, the present study demonstrated that AgNP accumulation in an aquatic environment may represent a potential source of toxicity and a risk for the viability of duckweeds.

  13. Study of charge-dependent transport and toxicity of peptide-functionalized silver nanoparticles using zebrafish embryos and single nanoparticle plasmonic spectroscopy.

    PubMed

    Lee, Kerry J; Browning, Lauren M; Nallathamby, Prakash D; Xu, Xiao-Hong Nancy

    2013-06-17

    Nanomaterials possess unusually high surface area-to-volume ratios and surface-determined physicochemical properties. It is essential to understand their surface-dependent toxicity in order to rationally design biocompatible nanomaterials for a wide variety of applications. In this study, we have functionalized the surfaces of silver nanoparticles (Ag NPs, 11.7 ± 2.7 nm in diameter) with three biocompatible peptides (CALNNK, CALNNS, CALNNE) to prepare positively (Ag-CALNNK NPs(+ζ)), negatively (Ag-CALNNS NPs(-2ζ)), and more negatively charged NPs (Ag-CALNNE NPs(-4ζ)), respectively. Each peptide differs in a single amino acid at its C-terminus, which minimizes the effects of peptide sequences and serves as a model molecule to create positive, neutral, and negative charges on the surface of the NPs at pH 4-10. We have studied their charge-dependent transport into early developing (cleavage-stage) zebrafish embryos and their effects on embryonic development using dark-field optical microscopy and spectroscopy (DFOMS). We found that all three Ag-peptide NPs passively diffused into the embryos via their chorionic pore canals, and stayed inside the embryos throughout their entire development (120 h), showing charge-independent diffusion modes and charge-dependent diffusion coefficients. Notably, the NPs create charge-dependent toxic effects on embryonic development, showing that the Ag-CALNNK NPs(+ζ) (positively charged) are the most biocompatible while the Ag-CALNNE NPs(-4ζ) (more negatively charged) are the most toxic. By comparing with our previous studies of the same sized citrated Ag and Au NPs, the Ag-peptide NPs are much more biocompatible than the citrated Ag NPs, and nearly as biocompatible as the Au NPs, showing the dependence of nanotoxicity upon the surface charges, surface functional groups, and chemical compositions of the NPs. This study also demonstrates powerful applications of single NP plasmonic spectroscopy for quantitative analysis of single

  14. Designing an ultra-sensitive aptasensor based on an AgNPs/thiol-GQD nanocomposite for TNT detection at femtomolar levels using the electrochemical oxidation of Rutin as a redox probe.

    PubMed

    Shahdost-Fard, Faezeh; Roushani, Mahmoud

    2017-01-15

    In this paper, for the first time a highly sensitive and low-cost electrochemical aptasensor was fabricated based on a silver nanoparticles/thiol functionalized graphene quantum dot (AgNPs/thiol-GQD) nanocomposite for the measurement of 2,4,6-Trinitrotoluen (TNT) as a nitroaromatic explosive. For the first time Rutin (RU) as a biological molecule with inherent properties was used as the redox probe in the development of the TNT aptasensor was used. The system was based on a TNT-binding aptamer which is covalently attached onto the surface of a glassy carbon electrode (GCE) modified with the nanocomposite for the formation of a sensing layer and improving the performance of the aptasensor. Using the proposed nanocomposite provides a specific platform with increased surface area which is capable of loading more Aptamer (Ap) molecules as a receptor element of TNT on the electrode surface. So, TNT molecules is in an upward position to be measured and the obtained results indicate that the aptasensor exhibits two wide linear ranges and an unprecedented LOD compared with previously reported analytical methods for TNT detection. Applicability of the developed aptasensor to easily detect TNT in real samples was evaluated. It seems that the proposed strategy can be expanded to other nanoparticles and is expected to have promising implications in the design of electrochemical sensors or biosensors for the detection of various targets.

  15. Mechanisms of silver nanoparticle-induced toxicity and important role of autophagy.

    PubMed

    Mao, Bin-Hsu; Tsai, Jui-Chen; Chen, Chun-Wan; Yan, Shian-Jang; Wang, Ying-Jan

    2016-10-01

    Safety concerns have been raised over the extensive applications of silver nanoparticles (AgNPs) because nano dimensions make them highly bioactive, being potentially harmful to the exposed humans. Surface physico-chemistry (shape, surface charge, chemical composition, etc.) that mainly dictates nano-bio interactions is relevant for influencing their biocompatibility and toxicity. Although the hazardousness of AgNPs has been demonstrated in vitro and in vivo, mechanistic understanding of the toxicity particularly at the molecular and organismal levels, in addition to oxidative stress and silver ion dissolution, has remained unclear. A growing body of research has elucidated that autophagy, being activated in response to exposure to various nanomaterials, may serve as a cellular defense mechanism against nanotoxicity. Recently, autophagy activation was shown to correlate with AgNPs exposure; however, the subsequent autophagosome-lysosome fusion was defective. As autophagy plays a crucial role in selective removal of stress-mediated protein aggregates and injured organelles, AgNPs-induced autophagic flux defect may consequently lead to aggravated cytotoxic responses. Furthermore, we suggest that p62 accumulation resulting from defective autophagy may also potentially account for AgNPs cytotoxicity. Intriguingly, AgNPs have been shown to interfere with ubiquitin modifications, either via upregulating levels of enzymes participating in ubiquitination, or through impairing the biological reactivity of ubiquitin (due to formation of AgNPs-ubiquitin corona). Ubiquitination both confers selectivity to autophagy as well as modulates stabilization, activation, and trafficking of proteins involved in autophagic clearance pathways. In this regard, we offer a new perspective that interference of AgNPs with ubiquitination may account for AgNPs-induced defective autophagy and cytotoxic effects.

  16. Differential antimicrobial activity of silver nanoparticles to bacteria Bacillus subtilis and Escherichia coli, and toxicity to crop plant Zea mays and beneficial B. subtilis-inoculated Z. mays

    NASA Astrophysics Data System (ADS)

    Doody, Michael A.; Wang, Dengjun; Bais, Harsh P.; Jin, Yan

    2016-10-01

    As silver nanoparticles (AgNPs) have become increasingly used in commercial antimicrobial agents and industrial and military products, concerns are increasing over their broad environmental and health impacts and risks because they are finding their way to the environment. This study was designed to quantify the antimicrobial activity of citrate-coated AgNPs (c-AgNPs; transmission electron microscope size of 44.9 ± 7.2 nm) to two species of bacteria, i.e., Gram-positive Bacillus subtilis and Gram-negative Escherichia coli, and toxicity to a major crop plant Zea mays and beneficial bacteria-inoculated plant (i.e., B. subtilis-inoculated Z. mays symbiont). Our results reveal that the exposure of c-AgNPs significantly inhibited bacteria growth and altered their growth kinetics. Z. mays experienced significant sublethal effects including reduced root length and biomass, and hyper-accumulation of Ag in roots. The beneficial interactions between B. subtilis and Z. mays were weakened as well because both species suffered sublethal effects. Potential mechanisms leading to the antimicrobial activity and toxicity of c-AgNPs to the bacteria, plant, and plant-bacteria symbiont examined in this study were discussed. Taken together, our findings advance the current knowledge of AgNPs antimicrobial property or toxicity to bacteria, crop plant, and beneficial plant-bacteria symbiotic interaction, which is a critical component for NPs environmental impact and risk assessment.

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

    PubMed

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

    2017-04-18

    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)), Zn(2+) 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 Zn(2+) 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

  18. Variable toxicity of silver nanoparticles to Daphnia magna: effects of algal particles and animal nutrition.

    PubMed

    Conine, Andrea L; Frost, Paul C

    2017-01-01

    Aquatic environments vary widely in aspects other than their physicochemical properties that could alter the toxicity of novel contaminants. One factor that could affect chemical toxicity to aquatic consumers is their nutritional environment as it can strongly affect their physiology and life history. Nutrition has the potential to alter an organism's response to the toxin or how the toxin interacts with the consumer through its food. Here we determined how growth and survival responses of Daphnia to an emerging contaminant, silver nanoparticles (AgNPs), are affected by the presence of food and its stoichiometric food quality. We used a series of survival tests, each slightly modified, to determine whether variable toxicity in different nutritional environments resulted from algal sequestration of AgNPs in a nontoxic form or from changes to the nutritional status of the test animals. We found that the presence of algae, of good or poor quality, reduced the toxicity of AgNPs on animal growth and survival. However, the decrease in AgNP toxicity was greater for animals consuming P-rich compared to P-poor food. We found evidence that this effect of food quality was due to greater algal uptake of AgNPs by P-rich than by P-stressed algae. However, we also found animal nutrition, in the absence of algal AgNP binding, could affect toxicity with P-nourished animals surviving slightly better when exposed to AgNPs compared to their P-stressed counterparts. Our results show an important role for algal particles and their P content in determining the toxicity of AgNPs in natural waters primarily due to their binding and uptake abilities and, less so, to their effects on animal nutrition.

  19. Effects of metal-bearing nanoparticles (Ag, Au, CdS, ZnO, SiO2) on developing zebrafish embryos

    NASA Astrophysics Data System (ADS)

    María Lacave, José; Retuerto, Ander; Vicario-Parés, Unai; Gilliland, Douglas; Oron, Miriam; Cajaraville, Miren P.; Orbea, Amaia

    2016-08-01

    Due to the increasing commercialization of consumer and industrial products containing nanoparticles (NPs), an increase in the introduction of these materials into the environment is expected. NP toxicity to aquatic organisms depends on multiple biotic and abiotic factors, resulting in an unlimited number of combinations impossible to test in practice. The zebrafish embryo model offers a useful screening tool to test and rank the toxicity of nanomaterials according to those diverse factors. This work aims to study the acute and sublethal toxicity of a set of metal-bearing NPs displaying different properties, in comparison to that of the ionic and bulk forms of the metals, in order to establish a toxicity ranking. Soluble NPs (Ag, CdS and ZnO) showed the highest acute and sublethal toxicity, with LC50 values as low as 0.529 mg Ag l-1 for Ag NPs of 20 nm, and a significant increase in the malformation prevalence in embryos exposed to 0.1 mg Cd l-1 of CdS NPs of ˜4 nm. For insoluble NPs, like SiO2 NPs, acute effects were not observed during early embryo development due to the protective effect of the chorion. But effects on larvae could be expected, since deposition of fluorescent SiO2 NPs over the gill lamella and excretion through the intestine were observed after hatching. In other cases, such as for gold NPs, the toxicity could be attributed to the presence of additives (sodium citrate) in the NP suspension, as they displayed a similar toxicity when tested separately. Overall, the results indicated that toxicity to zebrafish embryos depends primarily on the chemical composition and, thus, the solubility of the NPs. Other characteristics, such as size, played a secondary role. This was supported by the observation that ionic forms of the metals were always more toxic than the nano forms, and bulk forms were the least toxic to the developing zebrafish embryos.

  20. Toxicity of tannic acid-modified silver nanoparticles in keratinocytes: potential for immunomodulatory applications.

    PubMed

    Orlowski, Piotr; Soliwoda, Katarzyna; Tomaszewska, Emilia; Bien, Karolina; Fruba, Aleksandra; Gniadek, Marianna; Labedz, Olga; Nowak, Zuzanna; Celichowski, Grzegorz; Grobelny, Jarosław; Krzyzowska, Malgorzata

    2016-09-01

    Hydrolyzable tannins are known to exhibit anti-inflammatory activity, which can be used in combination with silver nanoparticles (AgNPs) for dermal uses. In this study, we investigated the effects of tannic acid-modified 13, 33, 46nm and unmodified 10-65nm AgNPs using the human-derived keratinocyte HaCaT and VK2-E6/E7 cell lines in the form of stationary and spheroids cultures. After exposition to tannic acid-modified AgNPs, VK2-E6/E7 cells showed higher toxicity, increased production of reactive oxygen species (ROS) and activity of JNK stress kinase, while HaCaT cell line demonstrated less ROS production and activation of ERK kinase. AgNPs internalization was detected both in the superficial and internal layers of spheroids prepared from both cell lines. Tannic acid modified AgNPs sized above 30nm did not induce DNA breaks in comet assay performed in both cell lines. Tannic acid-modified but not unmodified AgNPs down-regulated TNF-α and LPS-triggered production of IL-8 in VK2-E6/E7 but not in HaCaT cells. In summary, tannic acid-modified AgNPs sized above 30nm show good toxicological profile both in vitro and possess immunomodulatory properties useful for potential dermal applications in humans.

  1. 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

  2. Toxicity of two types of silver nanoparticles to aquatic crustaceans Daphnia magna and Thamnocephalus platyurus.

    PubMed

    Blinova, Irina; Niskanen, Jukka; Kajankari, Paula; Kanarbik, Liina; Käkinen, Aleksandr; Tenhu, Heikki; Penttinen, Olli-Pekka; Kahru, Anne

    2013-05-01

    Although silver nanoparticles (NPs) are increasingly used in various consumer products and produced in industrial scale, information on harmful effects of nanosilver to environmentally relevant organisms is still scarce. This paper studies the adverse effects of silver NPs to two aquatic crustaceans, Daphnia magna and Thamnocephalus platyurus. For that, silver NPs were synthesized where Ag is covalently attached to poly(vinylpyrrolidone) (PVP). In parallel, the toxicity of collargol (protein-coated nanosilver) and AgNO₃ was analyzed. Both types of silver NPs were highly toxic to both crustaceans: the EC50 values in artificial freshwater were 15-17 ppb for D. magna and 20-27 ppb for T. platyurus. The natural water (five different waters with dissolved organic carbon from 5 to 35 mg C/L were studied) mitigated the toxic effect of studied silver compounds up to 8-fold compared with artificial freshwater. The toxicity of silver NPs in all test media was up to 10-fold lower than that of soluble silver salt, AgNO₃. The pattern of the toxic response of both crustacean species to the silver compounds was almost similar in artificial freshwater and in natural waters. The chronic 21-day toxicity of silver NPs to D. magna in natural water was at the part-per-billion level, and adult mortality was more sensitive toxicity test endpoint than the reproduction (the number of offspring per adult).

  3. A novel method for assessing the toxicity of silver nanoparticles in Caenorhabditis elegans.

    PubMed

    Luo, Xun; Xu, Shengmin; Yang, Yaning; Zhang, Yajun; Wang, Shunchang; Chen, Shaopeng; Xu, An; Wu, Lijun

    2017-02-01

    At present, nanotechnology has been producing nanoscale materials with unprecedented speed. Nanomaterials could be inevitably released into the environment owing to their widespread use, and their potential toxicity has caused a great concern. With regard to assessment of nanomaterial toxicity, many studies probably don't truly reflect their toxicity, because the nanoparticles were not stable and uniformly dispersed in the medium. In the present study, the semi-fluid nematode growth gelrite medium (NGG) was used to achieve better distribution of silver nanoparticles (AgNPs). We aimed to evaluate the toxicity of AgNPs in three different culture methods, such as the NGG, nematode growth medium (NGM) and K-medium (KM). Our transmission electron microscopy, hydrodynamic diameter, and inductively coupled plasma-atomic emission spectrometry results demonstrated that AgNPs homogeneously and stably dispersed in NGG compared to that in liquid KM. Furthermore, the conventional toxicity end points, such as body length, fecundity, lifespan, population growth, germline cell apoptosis, reactive oxygen species, and mitochondrial membrane potential were used to assess the toxicity of AgNPs to Caenorhabditis elegans (C. elegans) in NGG, NGM and KM. Our results showed that the toxicity of AgNPs obtained in the NGG test medium was much higher than that in the standard NGM and KM. In addition to the improved dispersion of nanoparticles, NGG also offered advantages for long-term studies and likely provided a convenient nematode toxicity testing method. These results revealed that the NGG test medium was a suitable and sensitive culture method for the evaluation of AgNPs toxicity using C. elegans.

  4. Cellular Energy Allocation to Assess the Impact of Nanomaterials on Soil Invertebrates (Enchytraeids): The Effect of Cu and Ag.

    PubMed

    Gomes, Susana I L; Scott-Fordsmand, Janeck J; Amorim, Mónica J B

    2015-06-16

    The effects of several copper (Cu) and silver (Ag) nanomaterials were assessed using the cellular energy allocation (CEA), a methodology used to evaluate the energetic status and which relates with organisms' overall condition and response to toxic stress. Enchytraeus crypticus (Oligochatea), was exposed to the reproduction effect concentrations EC20/50 of several Cu and Ag materials (CuNO3, Cu-Field, Cu-Nwires and Cu-NPs; AgNO3, Ag NM300K, Ag-NPs Non-coated and Ag-NPs PVP-coated) for 7 days (0-3-7d). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (Ec) integrated to obtain the CEA. Results showed that these parameters allowed a clear discrimination between Cu and Ag, but less clearly within each of the various materials. For Cu there was an increase in Ec and protein budget, while for Ag a decrease was observed. The results corroborate known mechanisms, e.g., with Cu causing an increase in metabolic rate whereas Ag induces mitochondrial damage. The various Cu forms seem to activate different mechanisms with size and shape (e.g., Cu-NPs versus Cu-Nwires), causing clearly different effects. For Ag, results are in line with a slower oxidation rate of Ag-NMs in comparison with Ag-salt and hence delayed effects.

  5. Chemical and phase distributions in a multilayered organic matter-Ag nanoparticle thin film system

    NASA Astrophysics Data System (ADS)

    Michel, F. M.; Levard, C.; Wang, Y.; Choi, Y.; Eng, P.; Brown, G. E.

    2010-12-01

    Rapid development of nanotechnologies raises concern regarding the environmental impact of nanoparticles on ecosystems. Among the types of nanoparticles currently in production, metallic silver is the most widely used in nanotechnology (1). Synthetic Ag nanoparticles (Ag-NPs) are most often used for their antimicrobial and antifungal properties that are, in part, explained by the release of highly toxic Ag+ species (2). While such properties are desirable in certain applied cases, the release of Ag-NPs and soluble Ag+ species to the environment is expected to impact biota as well as soil and water quality (3). With the production of Ag-NPs projected to increase (1), the amount of Ag-NPs that will be released to the environment through waste streams is also likely to increase. As such, a deeper understanding of the fundamental processes associated with Ag-NPs toxicity and reactivity is needed to evaluate their impact on the environment. We have studied the interaction during aging of poly-acrylic acid (PAA) and Ag-NPs with average particle sizes of 20 ±5 nm. The sample studied was composed of thin films of PAA and Ag-NPs deposited on a Si-wafer support. PAA served as a model compound and a simplified surrogate for exopolysaccharide, an organic substance produced through metabolic activity by most microorganisms. We applied a novel combination of long-period x-ray standing wave fluorescence yield (XSW-FY) spectroscopy, grazing-incidence x-ray diffraction (GI-XRD), and XRD-based standing wave profiles (XSW-XRD) to obtain chemical- and phase-specific information on this sample. After 24 hours, we observed the formation of AgCl(s) in the PAA film of the sample, which suggests oxidation and dissolution of a portion of the Ag-NPs during aging, resulting in the release of Ag+. In addition, we see partitioning of Cl and Br, both present initially in the PAA, to the intact Ag-NPs thin film. To our knowledge, this is the first application of this suite of techniques to this

  6. 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.

  7. 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

  8. Uptake and translocation of metals and nutrients in tomato grown in soil polluted with metal oxide (CeO₂, Fe₃O₄, SnO₂, TiO₂) or metallic (Ag, Co, Ni) engineered nanoparticles.

    PubMed

    Vittori Antisari, Livia; Carbone, Serena; Gatti, Antonietta; Vianello, Gilmo; Nannipieri, Paolo

    2015-02-01

    The influence of exposure to engineered nanoparticles (NPs) was studied in tomato plants, grown in a soil and peat mixture and irrigated with metal oxides (CeO2, Fe3O4, SnO2, TiO2) and metallic (Ag, Co, Ni) NPs. The morphological parameters of the tomato organs, the amount of component metals taken up by the tomato plants from NPs added to the soil and the nutrient content in different tomato organs were also investigated. The fate, transport and possible toxicity of different NPs and nutrients in tomato tissues from soils were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The tomato yield depended on the NPs: Fe3O4-NPs promoted the root growth, while SnO2-NP exposure reduced it (i.e. +152.6 and -63.1 % of dry matter, respectively). The NP component metal mainly accumulated in the tomato roots; however, plants treated with Ag-, Co- and Ni-NPs showed higher concentration of these elements in both above-ground and below-ground organs with respect to the untreated plants, in addition Ag-NPs also contaminated the fruits. Moreover, an imbalance of K translocation was detected in some plants exposed to Ag-, Co- and Fe3O4-NPs. The component metal concentration of soil rhizosphere polluted with NPs significantly increased compared to controls, and NPs were detected in the tissues of the tomato roots using electron microscopy (ESEM-EDS).

  9. Toxic effects of colloidal nanosilver in zebrafish embryos.

    PubMed

    Olasagasti, Maider; Gatti, Antonietta M; Capitani, Federico; Barranco, Alejandro; Pardo, Miguel Angel; Escuredo, Kepa; Rainieri, Sandra

    2014-05-01

    A variety of consumer products containing silver nanoparticles (Ag NPs) are currently marketed. However, their safety for humans and for the environment has not yet been established and no standard method to assess their toxicity is currently available. The objective of this work was to develop an effective method to test Ag NP toxicity and to evaluate the effects of ion release and Ag NP size on a vertebrate model. To this aim, the zebrafish animal model was exposed to a solution of commercial nanosilver. While the exposure of embryos still surrounded by the chorion did not allow a definite estimation of the toxic effects exerted by the compound, the exposure for 48 h of 3-day-old zebrafish hatched embryos afforded a reliable evaluation of the effects of Ag NPs. The effects of the exposure were detected especially at molecular level; in fact, some selected genes expressed differentially after the exposure. The Ag NP toxic performance was due to the combined effect of Ag(+) ion release and Ag NP size. However, the effect of NP size was particularly detectable at the lowest concentration of nanosilver tested (0.01 mg l(-1)) and depended on the solubilization media. The results obtained indicate that in vivo toxicity studies of nanosilver should be performed with ad hoc methods (in this case using hatched embryos) that might be different depending on the type of nanosilver. Moreover, the addition of this compound to commercial products should take into consideration the Ag NP solubilization media.

  10. Canna edulis leaf extract-mediated preparation of stabilized silver nanoparticles: Characterization, antimicrobial activity, and toxicity studies.

    PubMed

    Otari, S V; Pawar, S H; Patel, Sanjay K S; Singh, Raushan K; Kim, Sang-Yong; Lee, Jai Hyo; Zhang, Liaoyuan; Lee, Jung-Kul

    2017-01-12

    A novel approach to synthesize silver nanoparticles (AgNPs) using leaf extract of Canna edulis Ker-Gawl. (CELE) under ambient conditions is reported here. The as-prepared AgNPs were analyzed by UV-visible spectroscopy, transmission emission microscopy, X-ray diffraction, Fourier transform-infra red spectroscopy, energy-dispersive analysis of X-ray spectroscopy, zeta potential, and dynamic light scattering. The AgNPs showed excellent antimicrobial activity against various pathogens, including bacteria and various fungi. The biocompatibility of the AgNPs was analyzed in the L929 cell line using NRU and MTT assays. Acridine orange/ethidium bromide staining was used to determine whether the AgNPs had necrotic or apoptotic effects on L929 cells. The concentration of AgNPs required for 50% inhibition of growth of mammalian cells is far more than that required for inhibition of pathogenic microorganisms. Thus, CELE is a candidate for eco-friendly, clean, cost-effective, and non-toxic synthesis of AgNPs.

  11. Acute toxicity of Ag and CuO nanoparticle suspensions against Daphnia magna: the importance of their dissolved fraction varying with preparation methods.

    PubMed

    Jo, Hun Je; Choi, Jae Woo; Lee, Sang Hyup; Hong, Seok Won

    2012-08-15

    A variety of methods to prepare nanoparticle suspensions have been employed for aquatic toxicity tests, although they can influence the dispersion property and subsequent toxicity of nanoparticles. Thus, in this study, we prepared stock suspensions of silver (Ag) and copper oxide (CuO) nanoparticles using different methods and compared their acute toxicity against Daphnia magna. The results showed that the dispersion method, filtration and initial concentration largely affected their toxicity, when the toxicity was expressed as the total concentrations of Ag and Cu. In case of Ag nanoparticles, the toxicity was also influenced by their different particle size. However, negligible differences in 24h-median effect concentration (EC(50)) values, which were calculated in terms of their dissolved concentrations, were observed. When expressing toxicity on the basis of dissolved concentrations, 24h-EC(50) values of the Ag and CuO nanoparticles were also found to be similar to those of the counterpart ionic species, i.e., Ag (as AgNO(3)) and Cu (as CuCl(2)·2H(2)O). These findings indicate that the dissolved fraction of nanoparticles largely contributes to their acute toxicity. Our results may help in establishing a useful guideline for preparing nanoparticle suspensions with reproducible toxicity.

  12. Study of Charge-Dependent Transport and Toxicity of Peptide-Functionalized Silver Nanoparticles Using Zebrafish Embryos and Single Nanoparticle Plasmonic Spectroscopy

    PubMed Central

    Lee, Kerry J.; Browning, Lauren M.; Nallathamby, Prakash D.; Xu, Xiao-Hong Nancy

    2013-01-01

    Nanomaterials possess unusually high surface area-to-volume ratios, and surface-determined physicochemical properties. It is essential to understand their surface-dependent toxicity in order to rationally design biocompatible nanomaterials for a wide variety of applications. In this study, we have functionalized the surfaces of silver nanoparticles (Ag NPs, 11.7 ± 2.7 nm in diameters) with three biocompatible peptides (CALNNK, CALNNS, CALNNE) to prepare positively (Ag-CALNNK NPs+ζ), negatively (Ag-CALNNS NPs−2ζ), and more negatively charged NPs (Ag-CALNNE NPs−4ζ), respectively. Each peptide differs in a single amino acid at its C-terminus, which minimizes the effects of peptide sequences and serves as a model molecule to create positive, neutral and negative charges on the surface of the NPs at pH 4–10. We have studied their charge-dependent transport into early-developing (cleavage-stage) zebrafish embryos and their effects on embryonic development using dark-field optical microscopy and spectroscopy (DFOMS). We found that all three Ag-peptide NPs passively diffused into the embryos via their chorionic pore canals, and stayed inside the embryos throughout their entire development (120 h), showing charge-independent diffusion modes and charge-dependent diffusion coefficients. Notably, the NPs create charge-dependent toxic effects on embryonic development, showing that the Ag-CALNNK NPs+ζ (positively charged) are the most biocompatible while the Ag-CALNNE NPs–4ζ (more negatively charged) are the most toxic. By comparing with our previous studies of the same sized citrated Ag and Au NPs, the Ag-peptide NPs are much more biocompatible than the citrated Ag NPs, and nearly as biocompatible as the Au NPs, showing the dependence of nanotoxicity upon the surface charges, surface functional groups and chemical compositions of the NPs. This study also demonstrates powerful applications of single NP plasmonic spectroscopy for quantitative analysis of single NPs

  13. Pulmonary Toxicity of Instilled Silver Nanoparticles: Influence of Size, Coating and Rat Strain

    PubMed Central

    Seiffert, Joanna; Hussain, Farhana; Wiegman, Coen; Li, Feng; Bey, Leo; Baker, Warren; Porter, Alexandra; Ryan, Mary P.; Chang, Yan; Gow, Andrew; Zhang, Junfeng; Zhu, Jie; Tetley, Terry D.; Chung, Kian Fan

    2015-01-01

    Particle size and surface chemistry are potential determinants of silver nanoparticle (AgNP) respiratory toxicity that may also depend on the lung inflammatory state. We compared the effects of intratracheally-administered AgNPs (20nm and 110nm; polyvinylpyrrolidone (PVP) and citrate-capped; 0.1 mg/Kg) in Brown-Norway (BN) and Sprague-Dawley (SD) rats. In BN rats, there was both a neutrophilic and eosinophilic response, while in SD rats, there was a neutrophilic response at day 1, greatest for the 20nm citrate-capped AgNPs. Eosinophilic cationic protein was increased in bronchoalveolar lavage (BAL) in BN and SD rats on day 1. BAL protein and malondialdehyde levels were increased in BN rats at 1 and 7 days, and BAL KC, CCL11 and IL-13 levels at day 1, with increased expression of CCL11 in lung tissue. Pulmonary resistance increased and compliance decreased at day 1, with persistence at day 7. The 20nm, but not the 110 nm, AgNPs increased bronchial hyperresponsiveness on day 1, which continued at day 7 for the citrate-capped AgNPs only. The 20nm versus the 110 nm size were more proinflammatory in terms of neutrophil influx, but there was little difference between the citrate-capped versus the PVP-capped AgNPs. AgNPs can induce pulmonary eosinophilic and neutrophilic inflammation with bronchial hyperresponsiveness, features characteristic of asthma. PMID:25747867

  14. Pulmonary toxicity of instilled silver nanoparticles: influence of size, coating and rat strain.

    PubMed

    Seiffert, Joanna; Hussain, Farhana; Wiegman, Coen; Li, Feng; Bey, Leo; Baker, Warren; Porter, Alexandra; Ryan, Mary P; Chang, Yan; Gow, Andrew; Zhang, Junfeng; Zhu, Jie; Tetley, Terry D; Chung, Kian Fan

    2015-01-01

    Particle size and surface chemistry are potential determinants of silver nanoparticle (AgNP) respiratory toxicity that may also depend on the lung inflammatory state. We compared the effects of intratracheally-administered AgNPs (20 nm and 110 nm; polyvinylpyrrolidone (PVP) and citrate-capped; 0.1 mg/Kg) in Brown-Norway (BN) and Sprague-Dawley (SD) rats. In BN rats, there was both a neutrophilic and eosinophilic response, while in SD rats, there was a neutrophilic response at day 1, greatest for the 20 nm citrate-capped AgNPs. Eosinophilic cationic protein was increased in bronchoalveolar lavage (BAL) in BN and SD rats on day 1. BAL protein and malondialdehyde levels were increased in BN rats at 1 and 7 days, and BAL KC, CCL11 and IL-13 levels at day 1, with increased expression of CCL11 in lung tissue. Pulmonary resistance increased and compliance decreased at day 1, with persistence at day 7. The 20 nm, but not the 110 nm, AgNPs increased bronchial hyperresponsiveness on day 1, which continued at day 7 for the citrate-capped AgNPs only. The 20 nm versus the 110 nm size were more proinflammatory in terms of neutrophil influx, but there was little difference between the citrate-capped versus the PVP-capped AgNPs. AgNPs can induce pulmonary eosinophilic and neutrophilic inflammation with bronchial hyperresponsiveness, features characteristic of asthma.

  15. Long and short term impacts of CuO, Ag and CeO2 nanoparticles on anaerobic digestion of municipal waste activated sludge.

    PubMed

    Ünşar, E Kökdemir; Çığgın, A S; Erdem, A; Perendeci, N A

    2016-02-01

    In this study, long and short term inhibition impacts of Ag, CuO and CeO2 nanoparticles (NPs) on anaerobic digestion (AD) of waste activated sludge (WAS) were investigated. CuO NPs were detected as the most toxic NPs on AD. As the CuO NP concentration increased from 5 to 1000 mg per gTS, an increase in the inhibition of AD from 5.8 to 84.0% was observed. EC50 values of short and long term inhibitions were calculated as 224.2 mgCuO per gTS and 215.1 mgCuO per gTS, respectively. Ag and CeO2 NPs did not cause drastic impacts on AD as compared to CuO NPs. In the long term test, Ag NPs created 12.1% decrease and CeO2 NPs caused 9.2% increase in the methane production from WAS at the highest dosage. FISH imaging also revealed that the abundance of Archaea in raw WAS was similar in short and long term tests carried out with WAS containing Ag and CeO2 NPs. On the other hand, CuO NPs caused inhibition of Archaea in the long term test. Digestion kinetics of WAS containing Ag, CeO2, CuO NPs were also evaluated with Gompertz, Logistic, Transference and First Order models. The hydrolysis rate constant (kH) for each concentration of Ag and CeO2 NPs and the raw WAS was 0.027745 d(-1) while the kH of WAS containing high concentrations of CuO NPs was found to be 0.001610 d(-1).

  16. Mechanochemically synthesized Ag-based nanohybrids with unprecedented low toxicity in biomedical applications.

    PubMed

    Arancon, Rick A D; Balu, Alina M; Romero, Antonio A; Ojeda, Manuel; Gomez, Mercedes; Blanco, Jordi; Domingo, Jose L; Luque, Rafael

    2017-04-01

    A simple and innovative mechanochemical approach was employed to synthesize Ag-polysaccharide nanohybrid materials that were proved to exhibit remarkable surface properties and structures for biomedical applications. The synthesized Ag nanomaterials possessed an unprecedented low cytotoxicity against human cell lines A549 and SH-SY5Y as compared to similarly reported Ag nanomaterials due to the stability and low release of Ag(+) and high biocompatibility of the nanohybrids.

  17. Oxidative Stress Mechanisms Caused by Ag Nanoparticles (NM300K) are Different from Those of AgNO3: Effects in the Soil Invertebrate Enchytraeus crypticus

    PubMed Central

    Ribeiro, Maria J.; Maria, Vera L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The mechanisms of toxicity of Ag nanoparticles (NPs) are unclear, in particular in the terrestrial environment. In this study the effects of AgNP (AgNM300K) were assessed in terms of oxidative stress in the soil worm Enchytraeus crypticus, using a range of biochemical markers [catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), total glutathione (TG), metallothionein (MT), lipid peroxidation (LPO)]. E. crypticus were exposed during 3 and 7 days (d) to the reproduction EC20, EC50 and EC80 levels of both AgNP and AgNO3. AgNO3 induced oxidative stress earlier (3 d) than AgNP (7 d), both leading to LPO despite the activation of the anti-redox system. MT increased only for AgNP. The Correspondence Analysis showed a clear separation between AgNO3 and AgNP, with e.g., CAT being the main descriptor for AgNP for 7 d. LPO, GST and GPx were for both 3 and 7 d associated with AgNO3, whereas MT and TG were associated with AgNP. These results may reflect a delay in the effects of AgNP compared to AgNO3 due to the slower release of Ag+ ions from the AgNP, although this does not fully explain the observed differences, i.e., we can conclude that there is a nanoparticle effect. PMID:26287225

  18. Toxicity and bioaccumulation of sediment-associated silver nanoparticles in the estuarine polychaete, Nereis (Hediste) diversicolor.

    PubMed

    Cong, Yi; Banta, Gary T; Selck, Henriette; Berhanu, Deborah; Valsami-Jones, Eugenia; Forbes, Valery E

    2014-11-01

    In this study, the toxicities of sediment-associated silver added to sediment as commercially available silver nanoparticles (Ag NPs, 20 and 80 nm) and aqueous Ag (AgNO3) to the estuarine polychaete, Nereis (Hediste) diversicolor, were investigated for both individual and subcellular endpoints after 10 d of exposure. Both Ag NP types were characterized in parallel to the toxicity studies and found to be polydispersed and overlapping in size. Burrowing activity decreased (marginally) with increasing Ag concentration and depended on the form of Ag added to sediment. All worms accumulated Ag regardless of the form in which it was added to the sediment, and worm size (expressed as dry weight) was found to significantly affect bioaccumulation such that smaller worms accumulated more Ag per body weight than larger worms. Lysosomal membrane permeability (neutral red retention time, NRRT) and DNA damage (comet assay tail moment and tail DNA intensity %) of Nereis coelomocytes increased in a concentration-dependent manner in all three Ag treatments. Ag NP treatments were more toxic than aqueous Ag for all toxicity endpoints, even though bioaccumulation did not differ significantly among Ag forms. No significant difference in toxicity was observed between the two Ag NP treatments which was attributed to their overlap in particle size.

  19. 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.

  20. Potential risk of acute toxicity induced by AgI cloud seeding on soil and freshwater biota.

    PubMed

    Fajardo, C; Costa, G; Ortiz, L T; Nande, M; Rodríguez-Membibre, M L; Martín, M; Sánchez-Fortún, S

    2016-11-01

    Silver iodide is one of the most common nucleating materials used in cloud seeding. Previous cloud seeding studies have concluded that AgI is not practically bioavailable in the environment but instead remains in soils and sediments such that the free Ag amounts are likely too low to induce a toxicological effect. However, none of these studies has considered the continued use of this practice on the same geographical areas and thus the potential cumulative effect of environmental AgI. The aim of this study is to assess the risk of acute toxicity caused by AgI exposure under laboratory conditions at the concentration expected in the environment after repeated treatments on selected soil and aquatic biota. To achieve the aims, the viability of soil bacteria Bacillus cereus and Pseudomonas stutzeri and the survival of the nematode Caenorhabditis elegans exposed to different silver iodide concentrations have been evaluated. Freshwater green algae Dictyosphaerium chlorelloides and cyanobacteria Microcystis aeruginosa were exposed to silver iodide in culture medium, and their cell viability and photosynthetic activity were evaluated. Additionally, BOD5 exertion and the Microtox® toxicity test were included in the battery of toxicological assays. Both tests exhibited a moderate AgI adverse effect at the highest concentration (12.5µM) tested. However, AgI concentrations below 2.5µM increased BOD5. Although no impact on the growth and survival endpoints in the soil worm C. elegans was recorded after AgI exposures, a moderate decrease in cell viability was found for both of the assessed soil bacterial strains at the studied concentrations. Comparison between the studied species showed that the cyanobacteria were more sensitive than green algae. Exposure to AgI at 0.43μM, the reference value used in monitoring environmental impact, induced a significant decrease in photosynthetic activity that is primarily associated with the respiration (80% inhibition) and, to a lesser

  1. Effects from Filtration, Capping Agents, and Presence/Absence of Food on the Toxicity of Silver Nanoparticles to Daphnia Magna

    EPA Science Inventory

    Relatively little is known regarding the behavior and toxicity of nanoparticles in the environment. The objectives of the work presented here include establishing the toxicity of a variety of silver nanoparticles (AgNPs) to Daphnia magna neonates, assessing the applicability of ...

  2. Proteomic evaluation of citrate-coated silver nanoparticles toxicity in Daphnia magna.

    PubMed

    Rainville, Louis-Charles; Carolan, Darragh; Varela, Ana Coelho; Doyle, Hugh; Sheehan, David

    2014-04-07

    Recent decades have seen a strong increase in the promise and uses of nanotechnology. This is correlated with their growing release in the environment and there is concern that nanomaterials may endanger ecosystems. Silver nanoparticles (AgNPs) have some of the most varied applications, making their release into the environment unavoidable. In order to assess their potential toxicity in aquatic environments, the acute toxicity of citrate-coated AgNPs to Daphnia magna was measured and compared to that of AgNO3. AgNPs were found to be ten times less toxic by mass than silver ions, and most of this toxicity was removed by ultracentrifuging. At the protein level, the two forms of silver had different impacts. Both increased protein thiol content, while only AgNP increased carbonyl levels. In 2DE of samples labelled for carbonyls, no feature was significantly affected by both compounds, indicating different modes of toxicity. Identified proteins showed functional overlap between the two compounds: vitellogenins (vtg) were present in most features identified, indicating their role as a general stress sensor. In addition to vtg, hemoglobin levels were increased by the AgNP exposure while 14-3-3 protein (a regulatory protein) carbonylation levels were reduced by AgNO3. Overall, this study confirms the previously observed lower acute toxicity of AgNPs, while demonstrating that the toxicity of both forms of silver follow somewhat different biologic pathways, potentially leading to different interactions with natural compounds or pollutants in the aquatic environment.

  3. 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

  4. Comparison of in vitro toxicity of silver ions and silver nanoparticles on human hepatoma cells.

    PubMed

    Vrček, Ivana Vinković; Žuntar, Irena; Petlevski, Roberta; Pavičić, Ivan; Dutour Sikirić, Maja; Ćurlin, Marija; Goessler, Walter

    2016-06-01

    Scientific information on the potential harmful effects of silver nanoparticles (AgNPs) on human health severely lags behind their exponentially growing applications in consumer products. In assessing the toxic risk of AgNP usage, liver, as a detoxifying organ, is particularly important. The aim of this study was to explore the toxicity mechanisms of nano and ionic forms of silver on human hepatoblastoma (HepG2) cells. The results showed that silver ions and citrate-coated AgNPs reduced cell viability in a dose-dependent manner. The IC50 values of silver ions and citrate-coated AgNPs were 0.5 and 50 mg L(-1) , respectively. The LDH leakage and inhibition of albumin synthesis, along with decreased ALT activity, indicated that treatment with either AgNP or Ag ions resulted in membrane damage and reduced the cell function of human liver cells. Evaluation of oxidative stress markers demonstrating depletion of GSH, increased ROS production, and increased SOD activity, indicated that oxidative stress might contribute to the toxicity effects of nano and ionic forms of silver. The observed toxic effect of AgNP on HepG2 cells was substantially weaker than that caused by ionic silver, while the uptake of nano and ionic forms of silver by HepG2 cells was nearly the same. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 679-692, 2016.

  5. Influence of Water Hardness on Silver Ion and Silver Nanoparticle Fate and Toxicity Toward Nitrosomonas europaea.

    PubMed

    Anderson, Joseph W; Semprini, Lewis; Radniecki, Tyler S

    2014-07-01

    This study investigated the influence of water hardness (Mg(2+) and Ca(2+)) on the fate and toxicity of 20 nm citrate silver nanoparticles (AgNPs) and Ag(+) toward Nitrosomonas europaea, a model ammonia-oxidizing bacterium. Nitrification inhibition of N. europaea by 1 ppm AgNPs and 0.5 ppm Ag(+) was reduced from 80% and 83%, respectively, in the absence of Mg(2+) to 2% and 33%, respectively, in the presence of 730 μM Mg(2+). Introduction of Mg(2+) resulted in the rapid aggregation of the AgNP suspensions and reduced the 3 h Ag(+) dissolution rates from 30%, in the absence of Mg(2+), to 9%, in the presence of 730 μM Mg(2+). Reduced AgNP dissolution rates resulted in decreased concentrations of silver that were found adsorbed to N. europaea cells. Increasing AgNP concentrations in the presence of Mg(2+) increased the observed inhibition of nitrification, but was always less than what was observed in the absence of Mg(2+). The presence of Mg(2+) also reduced the adsorption of Ag(+) to cells, possibly due to multiple mechanisms, including a reduction in the negative surface charge of the N. europaea membrane and a competition between Mg(2+) and Ag(+) for membrane binding sites and transport into the cells. Ca(2+) demonstrated similar protection mechanisms, as Ag(+) toxicity was reduced and AgNP suspensions aggregated and decreased their dissolution rates. These results indicate that the toxicity of Ag(+) and AgNPs to nitrifying bacteria in wastewater treatment would be less pronounced in systems with hard water.

  6. Toxicity assessment of silver nanoparticles in Persian sturgeon (Acipenser persicus) and starry sturgeon (Acipenser stellatus) during early life stages.

    PubMed

    Banan, Ashkan; Kalbassi Masjed Shahi, Mohammad Reza; Bahmani, Mahmoud; Yazdani Sadati, Mohammad Ali

    2016-05-01

    Silver nanoparticles (AgNPs) are widely used in consumer products mainly due to their antimicrobial action. The rapidly increasing use of nanoparticles (NPs) has driven more attention to their possible ecotoxicological effects. In this study, the acute toxicity of colloidal AgNPs was evaluated during the embryonic stage of Persian sturgeon (Acipenser persicus) and starry sturgeon (Acipenser stellatus) at concentrations of 0, 0.25, 0.5, 1, 2, 4, and 8 mg/L. Fertilized eggs (75 eggs per replicate) were exposed to aforementioned concentrations for 96 h in triplicate. 96-h LC50 values in Persian sturgeon and starry sturgeon were calculated as 0.163 and 0.158 mg/L, respectively. Furthermore, in starry sturgeon, the short-term effects of AgNPs on the hatching rate, survival rate, and Ag accumulation during early life stages (before active feeding commences) were also analyzed at concentrations of 0, 0.025, 0.05, and 0.1 mg/L of colloidal AgNPs. The highest silver accumulation occurred in larvae exposed to 0.1 mg/L AgNPs; however, the body burden of silver did not alter survival rate, and there were no significant differences among treatments. Based on the obtained results from the acute toxicity exposures, AgNPs induced a concentration-dependent toxicity in both species during early life stages, while complementary studies are suggested for investigating their short-term effects in detail.

  7. Investigation of antileishmanial activities of Tio2@Ag nanoparticles on biological properties of L. tropica and L. infantum parasites, in vitro.

    PubMed

    Allahverdiyev, Adil M; Abamor, Emrah Sefik; Bagirova, Melahat; Baydar, Serap Yesilkir; Ates, Sezen Canim; Kaya, Figen; Kaya, Cengiz; Rafailovich, Miriam

    2013-09-01

    Leishmaniasis is a public health problem which is caused by protozoon parasites belonging to Leishmania species. The disease threatens approximately 350 million people in 98 countries all over the world. Cutaneous Leishmaniasis (CL) and Visceral Leishmaniasis (VL) are the mostly commonly seen forms of the disease. Treatment of the disease has remained insufficient since current antileishmanial drugs have several disadvantages such as toxicity, costliness and drug-resistance. Therefore, there is an immediate need to search for new antileishmanial compounds. TiO2@Ag nanoparticles (TiAg-Nps) have been demonstrated as promising antimicrobial agents since they provide inhibition of several types of bacteria. The basic antimicrobial mechanism of TiAg-Nps is the generation of reactive oxygen species (ROS). Even though Leishmania parasites are sensitive to ROS, there is no study in literature indicating antileishmanial activities of TiAg-Nps. Herein, in this study, TiAg-Nps are shown to possess antileishmanial effects on Leishmania tropica and Leishmania infantum parasites by inhibiting their biological properties such as viability, metabolic activity, and survival within host cells both in the dark and under visible light. The results indicate that TiAg-Nps decreased viability values of L. tropica, and L. infantum promastigotes 3- and 10-fold, respectively, in the dark, while these rates diminished approximately 20-fold for each species in the presence of visible light, in contrast to control. On the other hand, non-visible light-exposed TiAg-Nps inhibited survival of amastigotes nearly 2- and 2.5-fold; while visible light-exposed TiAg-Nps inhibited 4- and 4.5-fold for L. tropica and L. infantum parasites, respectively. Consequently, it was determined that non-visible light-exposed TiAg-Nps were more effective against L. infantum parasites while visible light-exposed TiAg-Nps exhibited nearly the same antileishmanial effect against both species. Therefore, we think that a

  8. Uptake, Accumulation and Toxicity of Silver Nanoparticle in Autotrophic Plants, and Heterotrophic Microbes: A Concentric Review.

    PubMed

    Tripathi, Durgesh K; Tripathi, Ashutosh; Shweta; Singh, Swati; Singh, Yashwant; Vishwakarma, Kanchan; Yadav, Gaurav; Sharma, Shivesh; Singh, Vivek K; Mishra, Rohit K; Upadhyay, R G; Dubey, Nawal K; Lee, Yonghoon; Chauhan, Devendra K

    2017-01-01

    Nanotechnology is a cutting-edge field of science with the potential to revolutionize today's technological advances including industrial applications. It is being utilized for the welfare of mankind; but at the same time, the unprecedented use and uncontrolled release of nanomaterials into the environment poses enormous threat to living organisms. Silver nanoparticles (AgNPs) are used in several industries and its continuous release may hamper many physiological and biochemical processes in the living organisms including autotrophs and heterotrophs. The present review gives a concentric know-how of the effects of AgNPs on the lower and higher autotrophic plants as well as on heterotrophic microbes so as to have better understanding of the differences in effects among these two groups. It also focuses on the mechanism of uptake, translocation, accumulation in the plants and microbes, and resulting toxicity as well as tolerance mechanisms by which these microorganisms are able to survive and reduce the effects of AgNPs. This review differentiates the impact of silver nanoparticles at various levels between autotrophs and heterotrophs and signifies the prevailing tolerance mechanisms. With this background, a comprehensive idea can be made with respect to the influence of AgNPs on lower and higher autotrophic plants together with heterotrophic microbes and new insights can be generated for the researchers to understand the toxicity and tolerance mechanisms of AgNPs in plants and microbes.

  9. Uptake, Accumulation and Toxicity of Silver Nanoparticle in Autotrophic Plants, and Heterotrophic Microbes: A Concentric Review

    PubMed Central

    Tripathi, Durgesh K.; Tripathi, Ashutosh; Shweta; Singh, Swati; Singh, Yashwant; Vishwakarma, Kanchan; Yadav, Gaurav; Sharma, Shivesh; Singh, Vivek K.; Mishra, Rohit K.; Upadhyay, R. G.; Dubey, Nawal K.; Lee, Yonghoon; Chauhan, Devendra K.

    2017-01-01

    Nanotechnology is a cutting-edge field of science with the potential to revolutionize today’s technological advances including industrial applications. It is being utilized for the welfare of mankind; but at the same time, the unprecedented use and uncontrolled release of nanomaterials into the environment poses enormous threat to living organisms. Silver nanoparticles (AgNPs) are used in several industries and its continuous release may hamper many physiological and biochemical processes in the living organisms including autotrophs and heterotrophs. The present review gives a concentric know-how of the effects of AgNPs on the lower and higher autotrophic plants as well as on heterotrophic microbes so as to have better understanding of the differences in effects among these two groups. It also focuses on the mechanism of uptake, translocation, accumulation in the plants and microbes, and resulting toxicity as well as tolerance mechanisms by which these microorganisms are able to survive and reduce the effects of AgNPs. This review differentiates the impact of silver nanoparticles at various levels between autotrophs and heterotrophs and signifies the prevailing tolerance mechanisms. With this background, a comprehensive idea can be made with respect to the influence of AgNPs on lower and higher autotrophic plants together with heterotrophic microbes and new insights can be generated for the researchers to understand the toxicity and tolerance mechanisms of AgNPs in plants and microbes. PMID:28184215

  10. Testing Silver Nanoparticle Toxicity Using the Ammonia Oxidizing Bacteria Nitrosomonas Europaea and a High-throughput Assay

    NASA Astrophysics Data System (ADS)

    Semprini, L.; Bartow, S.; Radniecki, T.

    2012-04-01

    Understanding the toxicity of nanoparticles on ecologically significant wastewater microbiota, specifically ammonia oxidizing bacteria (AOB), is critical due to the exponential increase in commercialization of nanoparticles as well as the sensitivity of AOB to inhibitors. A high-throughput activity assay was developed to rapidly screen for nanoparticle toxicity on AOB, using a multi-well plate method and AOB Nitrosomonas Europaea. This method demonstrated good agreement with previously established batch bottle assays utilizing both silver ions (Ag+) and nanoparticles (Ag-NPs) as nitrification inhibitors. The method was used to study the inhibition of Ag+ and Ag-NPs (20 nm) on the nitrification by N. Europaea cells grown in fill-and-draw reactors compared exponentially grown batch cells. Results indicate longer hydraulic residence times increased some protection against inhibition as measured by the production of nitrite over a three hour assay. The cells were more sensitive to Ag+ than Ag-NP, which is consistent with our past observations. Studies are currently being conducted to determine the effects that the presence of humic acid and cations on the inhibition and toxicity. Our initial results show that the presence of Mg++ provides protect from Ag-NP inhibition, which partly results from the aggregation of the Ag-NP and a decrease in the rate of oxidation of the Ag-NP to Ag+. The presence of humic acid also provides for some protection from Ag-NP inhibition.

  11. Reproductive Toxicity and Life History Study of Silver Nanoparticle Effect, Uptake and Transport in Arabidopsis thaliana

    PubMed Central

    Geisler-Lee, Jane; Brooks, Marjorie; Gerfen, Jacob R.; Wang, Qiang; Fotis, Christin; Sparer, Anthony; Ma, Xingmao; Berg, R. Howard; Geisler, Matt

    2014-01-01

    Concerns about nanotechnology have prompted studies on how the release of these engineered nanoparticles impact our environment. Herein, the impact of 20 nm silver nanoparticles (AgNPs) on the life history traits of Arabidopsis thaliana was studied in both above- and below-ground parts, at macroscopic and microscopic scales. Both gross phenotypes (in contrast to microscopic phenotypes) and routes of transport and accumulation were investigated from roots to shoots. Wild type Arabidopsis growing in soil, regularly irrigated with 75 μg/L of AgNPs, did not show any obvious morphological change. However, their vegetative development was prolonged by two to three days and their reproductive growth shortened by three to four days. In addition, the germination rates of offspring decreased drastically over three generations. These findings confirmed that AgNPs induce abiotic stress and cause reproductive toxicity in Arabidopsis. To trace transport of AgNPs, this study also included an Arabidopsis reporter line genetically transformed with a green fluorescent protein and grown in an optical transparent medium with 75 μg/L AgNPs. AgNPs followed three routes: (1) At seven days after planting (DAP) at S1.0 (stages defined by Boyes et al. 2001 [41]), AgNPs attached to the surface of primary roots and then entered their root tips; (2) At 14 DAP at S1.04, as primary roots grew longer, AgNPs gradually moved into roots and entered new lateral root primordia and root hairs; (3) At 17 DAP at S1.06 when the Arabidopsis root system had developed multiple lateral roots, AgNPs were present in vascular tissue and throughout the whole plant from root to shoot. In some cases, if cotyledons of the Arabidopsis seedlings were immersed in melted transparent medium, then AgNPs were taken up by and accumulated in stomatal guard cells. These findings in Arabidopsis are the first to document specific routes and rates of AgNP uptake in vivo and in situ.

  12. Aquatic Toxicity Comparison of Silver Nanoparticles and Silver Nanowires.

    PubMed

    Sohn, Eun Kyung; Johari, Seyed Ali; Kim, Tae Gyu; Kim, Jin Kwon; Kim, Ellen; Lee, Ji Hyun; Chung, Young Shin; Yu, Il Je

    2015-01-01

    To better understand the potential ecotoxicological impact of silver nanoparticles (AgNPs) and silver nanowires (AgNWs) released into freshwater environments, the toxicities of these nanomaterials were assessed and compared using Organization for Economic Cooperation and Development (OECD) test guidelines, including a "Daphnia sp., acute immobilization test," "Fish, acute toxicity test," and "freshwater alga and cyanobacteria, growth inhibition test." Based on the estimated median lethal/effective concentrations of AgNPs and AgNWs, the susceptibility to the nanomaterials was different among test organisms (daphnia > algae > fish), suggesting that the AgNPs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 1" for Raphidocelis subcapitata, while the AgNWs are classified as "category acute 1" for Daphnia magna, "category acute 2" for Oryzias latipes, and "category acute 2" for Raphidocelis subcapitata, according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals). In conclusion, the present results suggest that more attention should be paid to prevent the accidental or intentional release of silver nanomaterials into freshwater aquatic environments.

  13. Validation of an LDH Assay for Assessing Nanoparticle Toxicity

    PubMed Central

    Han, Xianglu; Gelein, Robert; Corson, Nancy; Wade-Mercer, Pamela; Jiang, Jingkun; Biswas, Pratim; Finkelstein, Jacob N.; Elder, Alison; Oberdörster, Günter

    2014-01-01

    Studies showed that certain cytotoxicity assays were not suitable for assessing nanoparticle (NP) toxicity. We evaluated a lactate dehydrogenase (LDH) assay for assessing copper (Cu-40, 40 nm), silver (Ag-35, 35 nm; Ag-40, 40 nm), and titanium dioxide (TiO2-25, 25 nm) NPs by examining their potential to inactivate LDH and interference with β-nicotinamide adenine dinucleotide (NADH), a substrate for the assay. We also performed a dissolution assay for some of the NPs. We found that the copper NPs, because of their high dissolution rate, could interfere with the LDH assay by inactivating LDH. Ag-35 could also inactivate LDH probably because of the carbon matrix used to cage the particles during synthesis. TiO2-25 NPs were found to adsorb LDH molecules. In conclusion, NP interference with the LDH assay depends on the type of NPs and the suitability of the assay for assessing NP toxicity should be examined case by case. PMID:21722700

  14. Development of a supramolecular ensemble of an AIEE active hexaphenylbenzene derivative and Ag@Cu2O core-shell NPs: an efficient photocatalytic system for C-H activation.

    PubMed

    Chopra, Radhika; Kumar, Manoj; Bhalla, Vandana

    2016-08-09

    A supramolecular ensemble having Ag@Cu2O core-shell nanoparticles stabilized by aggregates of a hexaphenylbenzene derivative has been developed which exhibits excellent photocatalytic efficiency in reactions involving preparation of imidazole and benzimidazole derivatives via C-H activation.

  15. ZnO-Ag core shell nanocomposite formed by green method using essential oil of wild ginger and their bactericidal and cytotoxic effects

    NASA Astrophysics Data System (ADS)

    Azizi, Susan; Mohamad, Rosfarizan; Rahim, Raha Abdul; Moghaddam, Amin Boroumand; Moniri, Mona; Ariff, Arbakariya; Saad, Wan Zuhainis; Namvab, Farideh

    2016-10-01

    In this paper, a novel green method for fabrication of zinc oxide-silver (ZnO-Ag) core-shell nanocomposite using essential oil of ginger (EO-G) is reported. The EO-G played two significant roles in the synthesis process: it could act as a reaction media for the formation of ZnO and reduce Ag+ to Ag0. The bioformed ZnO-Ag nanocomposite was compared with pure biosynthesized ZnO-NPs and characterized by UV-vis spectroscopy, TEM, EDX, XRD and FTIR. The characterization results confirmed that Ag-NPs had been embedded in ZnO hexagonal nanoparticles. Six Gram positive and negative pathogens were used to investigate the antibacterial effects of these samples. Ag-doping improves the bactericidal activity of ZnO-NPs. In vitro cytotoxicity studies on Vero cells, a dose dependent toxicity with non-toxic effect of concentration below 100 μg/mL was shown for ZnO-Ag nanocomposite. The biosynthesized ZnO-Ag nanocomposites were found to be comparable to those obtained from the conventional methods using hazardous materials which can be an excellent alternative for the synthesis of ZnO-Ag using biomass.

  16. Toxicity assessment on haemotology, biochemical and histopathological alterations of silver nanoparticles-exposed freshwater fish Labeo rohita

    NASA Astrophysics Data System (ADS)

    Rajkumar, K. S.; Kanipandian, N.; Thirumurugan, R.

    2016-01-01

    The increasing use of nano based-products induces the potential hazards from their manufacture, transportation, waste disposal and management processes. In this report, we emphasized the acute toxicity of silver nanoparticles (AgNPs) using freshwater fish Labeo rohita as an aquatic animal model. The AgNPs were synthesized using chemical reduction method and the formation of AgNPs was monitored by UV-Visible spectroscopy analysis. The functional groups, crystaline nature and morphological characterizations were carried out by fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analysis. UV-Vis range was observed at 420 nm and XRD pattern showed that the particles are crystalline nature. HRTEM analysis revealed that the morphology of particles was spherical and size ranges between 50 and 100 nm. This investigation was extended to determine the potential acute toxicity, L. rohita was treated orally with the lethal concentration (LC50) of AgNPs. The antioxidative responses were studied in the three major tissues such as gill, liver and muscle of L. rohita. The results of this investigation showed that increasing the concentration of AgNPs led to bioaccumulation of AgNPs in the major tissues. The haematological parameters showed significant alterations in the treated fish. The histological changes caused by chemically synthesized AgNPs demonstrated the damages in the tissues, primary lamella and blood vessels of L. rohita. The histological study also displayed the formation of vacuolation in liver and muscle when compared with untreated tissues (control) of L. rohita.

  17. Applications and toxicity of silver nanoparticles: a recent review.

    PubMed

    Marin, Stefania; Vlasceanu, George Mihail; Tiplea, Roxana Elena; Bucur, Ioana Raluca; Lemnaru, Madalina; Marin, Maria Minodora; Grumezescu, Alexandru Mihai

    2015-01-01

    Silver nanoparticles (AgNPs) exhibit a consistent amount of flexible properties which endorse them for a larger spectrum of applications in biomedicine and related fields. Over the years, silver nanoparticles have been subjected to numerous in vitro and in vivo tests to provide information about their toxic behavior towards living tissues and organisms. Researchers showed that AgNPs have high antimicrobial efficacy against many bacteria species including Escherichia coli, Neisseria gonorrhea, Chlamydia trachomatis and also viruses. Due to their novel properties, the incorporation of silver nanoparticles into different materials like textile fibers and wound dressings can extend their utility on the biomedical field while inhibiting infections and biofilm development. Among the noble metal nanoparticles, AgNPs present a series of features like simple synthesis routes, adequate and tunable morphology, and high surface to volume ratio, intracellular delivery system, a large plasmon field area recommending them as ideal biosensors, catalysts or photo-controlled delivery systems. In bioengineering, silver nanoparticles are considered potentially ideal gene delivery systems for tissue regeneration. The remote triggered detection and release of bioactive compounds of silver nanoparticles has proved their relevance also in forensic sciences. The authors report an up to date review related to the toxicity of AgNPs and their applications in antimicrobial activity and biosensors for gene therapy.

  18. Toxicity of citrate-coated silver nanoparticles differs according to method of suspension preparation.

    PubMed

    Park, June-Woo; Oh, Ji-Hyun; Kim, Woo-Keun; Lee, Sung-Kyu

    2014-07-01

    To evaluate substance toxicity, it is critical to maintain specific concentrations of test substances throughout the exposure period. During the last decade, the need to improve methods for nanoparticle (NP) suspension preparations has gained attention because many published results on NPs toxicity have been inconsistent. Here, we compared the toxicity of citrate-coated silver nanoparticles (AgNPs) suspended by two different methods (fractionated vs. colloidal) in freshwater organisms (daphnia and medaka). Analytical methods (ICP-OES, DLS and UV absorbance) were employed to characterize behavior of AgNPs in suspension. Results showed that fractionated (stirred and settled) solution was less toxic to daphnia (13.8 µg/L) than colloidal solution (6.1 µg/L), suggesting that method of preparation was a critical factor that affected toxicity. However, differences in toxicity caused by suspension methods were not observed in medaka. Results indicate that the method used to prepare suspensions of NPs can affect toxicity, and that differences can exist among test organisms.

  19. 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

  20. SILVER NANOPARTICLE INDUCED OXIDATIVE STRESS-DEPENDENT TOXICITY IN SPRAGUE-DAWLEY RATS

    PubMed Central

    Patlolla, Anita K.; Hackett, Diahanna; Tchounwou, Paul B.

    2014-01-01

    Due to the intensive commercial application of silver nanoparticles (Ag-NPs), their health risk assessment is of great importance. For acute toxicity evaluation of orally administered Ag-NPs, induction of reactive oxygen species (ROS), activity of liver function enzymes [(Alanine (ALT/GPT), Aspartate (AST/GOT), Alkaline Phosphatase (ALP)], concentration of lipid hydroperoxide (LHP), comet assay and histopathology of liver in the rat model were performed. Four groups of five male rats were orally administered Ag-NPs, once a day for five days with doses of 5, 25, 50, 100, mg/Kg, body weight. A control group was also made of five rats. Blood and liver were collected 24 hours after the last treatment following standard protocols. Ag-NPs exposure increased the induction of ROS, activities of the liver enzymes (ALT, AST, ALP), concentration of Lipid hydroperoxide (LHP), tail migration and morphological alterations of the liver tissue in exposed groups compared to control. The highest two doses, 50 mg/kg and 100 mg/kg showed statistically significant (p<0.05) increases in ROS induction, ALT, AST, ALP activity, LHP concentration, DNA damage and morphological alterations of liver compared to control. Based on these results, it is suggested that short-term administration of high doses of Ag-NP may cause organ toxicity and oxidative stress. PMID:25355157

  1. Effects from filtration, capping agents, and presence/absence of food on the toxicity of silver nanoparticles to Daphnia magna.

    PubMed

    Allen, H Joel; Impellitteri, Christopher A; Macke, Dana A; Heckman, J Lee; Poynton, Helen C; Lazorchak, James M; Govindaswamy, Shekar; Roose, Deborah L; Nadagouda, Mallikarjuna N

    2010-12-01

    Relatively little is known about the behavior and toxicity of nanoparticles in the environment. Objectives of work presented here include establishing the toxicity of a variety of silver nanoparticles (AgNPs) to Daphnia magna neonates, assessing the applicability of a commonly used bioassay for testing AgNPs, and determining the advantages and disadvantages of multiple characterization techniques for AgNPs in simple aquatic systems. Daphnia magna were exposed to a silver nitrate solution and AgNPs suspensions including commercially available AgNPs (uncoated and coated), and laboratory-synthesized AgNPs (coated with coffee or citrate). The nanoparticle suspensions were analyzed for silver concentration (microwave acid digestions), size (dynamic light scattering and electron microscopy), shape (electron microscopy), surface charge (zeta potentiometer), and chemical speciation (X-ray absorption spectroscopy, X-ray diffraction). Toxicities of filtered (100 nm) versus unfiltered suspensions were compared. Additionally, effects from addition of food were examined. Stock suspensions were prepared by adding AgNPs to moderately hard reconstituted water, which were then diluted and used straight or after filtration with 100-nm filters. All nanoparticle exposure suspensions, at every time interval, were digested via microwave digester and analyzed by inductively coupled argon plasma-optical emission spectroscopy or graphite furnace-atomic absorption spectroscopy. Dose-response curves were generated and median lethal concentration (LC50) values calculated. The LC50 values for the unfiltered particles were (in µg/L): 1.1 ± 0.1-AgNO(3) ; 1.0 ± 0.1-coffee coated; 1.1 ± 0.2-citrate coated; 16.7 ± 2.4 Sigma Aldrich Ag-nanoparticles (SA) uncoated; 31.5 ± 8.1 SA coated. LC50 values for the filtered particles were (in µg/L): 0.7 ± 0.1-AgNO(3) ; 1.4 ± 0.1-SA uncoated; 4.4 ± 1.4-SA coated. The LC50 resulting from the addition of food was 176.4 ± 25.5-SA coated

  2. Toxicity Testing of Silver Nanoparticles in Artificial and Natural Sediments Using the Benthic Organism Lumbriculus variegatus.

    PubMed

    Rajala, Juho Elias; Mäenpää, Kimmo; Vehniäinen, Eeva-Riikka; Väisänen, Ari; Scott-Fordsmand, Janeck James; Akkanen, Jarkko; Kukkonen, Jussi Vilho Kalevi

    2016-10-01

    The increased use of silver nanoparticles (AgNP) in industrial and consumer products worldwide has resulted in their release to aquatic environments. Previous studies have mainly focused on the effects of AgNP on pelagic species, whereas few studies have assessed the risks to benthic invertebrates despite the fact that the sediments act as a large potential sink for NPs. In this study, the toxicity of sediment-associated AgNP was evaluated using the standard sediment toxicity test for chemicals provided by the Organization of Economic Cooperation and Development. The freshwater benthic oligochaete worm Lumbriculus variegatus was exposed to sediment-associated AgNP in artificial and natural sediments at concentrations ranging from 91 to 1098 mg Ag/kg sediment dry weight. Silver nitrate (AgNO3) was used as a reference compound for Ag toxicity. The measured end points of toxicity were mortality, reproduction, and total biomass. In addition, the impact of sediment-associated AgNP on the feeding rate of L. variegatus was studied in a similar test set-up as mentioned previously. The addition of AgNP into the sediment significantly affected the feeding rate and reproduction of the test species only at the highest concentration (1098 mg/kg) of Ag in the natural sediment with the lowest pH. In comparison, the addition of AgNO3 resulted in reproductive toxicity in every tested sediment, and Ag was more toxic when spiked as AgNO3 than AgNP. In general, sediments were observed to have a high capacity to eliminate the AgNP-derived toxicity. However, the capacity of sediments to eliminate the toxicity of Ag follows a different pattern when spiked as AgNP than AgNO3. The results of this study emphasize the importance of sediment-toxicity testing and the role of sediment properties when evaluating the environmental effects and behavior of AgNP in sediments.

  3. One-pot fabrication of silver nanocrystals using Nicandra physalodes: A novel route for mosquito vector control with moderate toxicity on non-target water bugs.

    PubMed

    Govindarajan, Marimuthu; Khater, Hanem F; Panneerselvam, Chellasamy; Benelli, Giovanni

    2016-08-01

    Mosquitoes (Diptera: Culicidae) as vectors for important diseases and parasites causing millions of deaths every year. The use of synthetic pesticides against Culicidae leads to resistance and environmental concerns. Therefore, eco-friendly control tools are a priority. In this research, Nicandra physalodes-mediated synthesis of silver nanoparticles (Ag NPs) was conducted, in order to control larval populations of three important mosquito vectors, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus. Biofabricated Ag NPs were characterized using UV-vis spectrophotometry, XRD, FTIR spectroscopy, SEM, and TEM analyses. Ag NPs were highly toxic against the three mosquito vectors. Maximum efficacy was detected against A. stephensi (LC50=12.39μg/mL), followed by Ae. aegypti (LC50=13.61μg/mL) and Cx. quinquefasciatus (LC50=14.79μg/mL). Interestingly, Ag NPs were safer for the non-target aquatic organism Diplonychus indicus sharing the same aquatic habitats of mosquito larvae. LC50 and LC90 values were 1032.81 and 19,076.59μg/mL, respectively. Overall, our results highlight that N. physalodes-fabricated Ag NPs are a promising for development of eco-friendly larvicides against mosquito vectors, with negligible toxicity against non-target aquatic water bugs.

  4. Silver nanoparticles: therapeutical uses, toxicity, and safety issues.

    PubMed

    dos Santos, Carolina Alves; Seckler, Marcelo Martins; Ingle, Avinash P; Gupta, Indarchand; Galdiero, Stefania; Galdiero, Massimiliano; Gade, Aniket; Rai, Mahendra

    2014-07-01

    The promises of nanotechnology have been realized to deliver the greatest scientific and technological advances in several areas. The biocidal activity of Metal nanoparticles in general and silver nanoparticles (AgNPs) depends on several morphological and physicochemical characteristics of the particles. Many of the interactions of the AgNPs with the human body are still poorly understood; consequently, the most desirable characteristics for the AgNPs are not yet well established. Therefore, the development of nanoparticles with well-controlled morphological and physicochemical features for application in human body is still an active area of interdisciplinary research. Effects of the development of technology of nanostructured compounds seem to be so large and comprehensive that probably it will impact on all fields of science and technology. However, mechanisms of safety control in application, utilization, responsiveness, and disposal accumulation still need to be further studied in-depth to ensure that the advances provided by nanotechnology are real and liable to provide solid and consistent progress. This review aims to discuss AgNPs applied in biomedicine and as promising field for insertion and development of new compounds related to medical and pharmacy technology. The review also addresses drug delivery, toxicity issues, and the safety rules concerning biomedical applications of silver nanoparticles.

  5. Toxicity of silver and gold nanoparticles on marine microalgae.

    PubMed

    Moreno-Garrido, Ignacio; Pérez, Sara; Blasco, Julián

    2015-10-01

    The increased use of nanomaterials in several novel industrial applications during the last decade has led to a rise in concerns about the potential toxic effects of released engineered nanoparticles (NPs) into the environment, as their potential toxicity to aquatic organisms is just beginning to be recognised. Toxicity of metallic nanoparticles to aquatic organisms, including microalgae, seems to be related to their physical and chemical properties, as well as their behaviour in the aquatic media where processes of dissolution, aggregation and agglomeration can occur. Although the production of these particles has increased considerably in recent years, data on their toxicity on microalgae, especially those belonging to marine or estuarine environments remain scarce and scattered. The literature shows a wide variation of results on toxicity, mainly due to the different methodology used in bioassays involving microalgae. These can range for up to EC50 data, in the case of AgNPs, representing five orders of magnitude. The importance of initial cellular density is also addressed in the text, as well as the need for keeping test conditions as close as possible to environmental conditions, in order to increase their environmental relevance. This review focuses on the fate and toxicity of silver, gold, and gold-silver alloy nanoparticles on microalgae, as key organisms in aquatic ecosystems. It is prompted by their increased production and use, and taking into account that oceans and estuaries are the final sink for those NPs. The design of bioassays and further research in the field of microalgae nanoecotoxicology is discussed, with a brief survey on newly developed technology of green (algae mediated) production of Ag, Au and Ag-Au bimetallic NPs, as well as some final considerations about future research on this field.

  6. Ag@AgI, core@shell structure in agarose matrix as hybrid: synthesis, characterization, and antimicrobial activity.

    PubMed

    Ghosh, Somnath; Saraswathi, A; Indi, S S; Hoti, S L; Vasan, H N

    2012-06-05

    A novel in situ core@shell structure consisting of nanoparticles of Ag (Ag Nps) and AgI in agarose matrix (Ag@AgI/agarose) has been synthesized as a hybrid, in order to have an efficient antibacterial agent for repetitive usage with no toxicity. The synthesized core@shell structure is very well characterized by XRD, UV-visible, photoluminescence, and TEM. A detailed antibacterial studies including repetitive cycles are carried out on Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria in saline water, both in dark and on exposure to visible light. The hybrid could be recycled for the antibacterial activity and is nontoxic toward human cervical cancer cells (HeLa cells). The water insoluble Ag@AgI in agarose matrix forms a good coating on quartz, having good mechanical strength. EPR and TEM studies are carried out on the Ag@AgI/agarose and the bacteria, respectively, to elucidate a possible mechanism for killing of the bacteria.

  7. Development of dual-fluorescence cell-based biosensors for detecting the influence of environmental factors on nanoparticle toxicity.

    PubMed

    Liang, Junting; Wang, Xuanyu; Li, Luzhi; Xu, Shengmin; Jiang, Jiang; Wu, Lijun; Zhao, Guoping; Chen, Shaopeng

    2017-03-01

    With the expanding use of engineered nanoparticles (NPs), development of a high-throughput, sensitive method for evaluating NP safety is important. In this study, we developed cell-based biosensors to efficiently and conveniently monitor NP toxicity. The biosensor cells were obtained by transiently transfecting human cells with biosensor plasmids containing a mCherry gene regulated by an inducible promoter [an activator protein 1 (AP-1) promoter, an interleukin 8 (IL8) promoter, or a B cell translocation gene 2 (BTG2) promoter], with an enhanced green-fluorescent protein gene driven by the cytomegalovirus promoter as the internal control. After optimizing flow cytometric analysis, these dual-fluorescence cell-based biosensors were capable of accurately and rapidly detecting NP toxicity. We found that the responses of AP-1, BTG2, and IL8 biosensors in assessing the toxicity of silver nanoparticles (Ag NPs) showed good dose-related increases after exposure to Ag NPs and were consistent with data acquired by conventional assays, such as western blot, real-time polymerase chain reaction, and immunofluorescence. Further investigation of the effects of environmental factors on Ag NP toxicity revealed that aging in water, co-exposure with fulvic acid, and irradiation with ultraviolet A light could affect Ag NP-induced biosensor responses. These results indicated that these novel dual-fluorescence biosensors can be applied to accurately and sensitively monitor NP toxicity.

  8. Facile synthesis of AgCl/polydopamine/Ag nanoparticles with in-situ laser improving Raman scattering effect

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Zhang, Wenqi; Wang, Lin; Wang, Feng; Yang, Haifeng

    2017-01-01

    We reported a simple and fast method to prepare a composite material of polydopamine (PDA) adlayer covered cubic AgCl core, which was inlaid with Ag nanoparticles (NPs), shortly named as AgCl/PDA/AgNPs. The resultant AgCl/PDA/AgNPs could be employed as surface-enhanced Raman scattering (SERS) substrate for in-situ detection and the SERS activity could be further greatly improved due to the production of more AgNPs upon laser irradiation. With 4-mercaptopyridine (4-Mpy) as the probe molecule, the enhancement factor could reach 107. Additionally, such SERS substrate shows good reproducibility with relative standard deviation of 7.32% and long term stability (after storage for 100 days under ambient condition, SERS intensity decay is less than 25%). In-situ elevating SERS activity of AgCl/PDA/AgNPs induced by laser may be beneficial to sensitive analysis in practical fields.

  9. Biosynthesis, characterization, and acute toxicity of Berberis tinctoria-fabricated silver nanoparticles against the Asian tiger mosquito, Aedes albopictus, and the mosquito predators Toxorhynchites splendens and Mesocyclops thermocyclopoides.

    PubMed

    Kumar, Palanisamy Mahesh; Murugan, Kadarkarai; Madhiyazhagan, Pari; Kovendan, Kalimuthu; Amerasan, Duraisamy; Chandramohan, Balamurugan; Dinesh, Devakumar; Suresh, Udaiyan; Nicoletti, Marcello; Alsalhi, Mohamad Saleh; Devanesan, Sandhanasamy; Wei, Hui; Kalimuthu, Kandasamy; Hwang, Jiang-Shiou; Lo Iacono, Annalisa; Benelli, Giovanni

    2016-02-01

    Aedes albopictus is an important arbovirus vector, including dengue. Currently, there is no specific treatment for dengue. Its prevention solely depends on effective vector control measures. In this study, silver nanoparticles (AgNPs) were biosynthesized using a cheap leaf extract of Berberis tinctoria as reducing and stabilizing agent and tested against Ae. albopictus and two mosquito natural enemies. AgNPs were characterized by using UV–vis spectrophotometry, X-ray diffraction, and scanning electron microscopy. In laboratory conditions, the toxicity of AgNPs was evaluated on larvae and pupae of Ae. albopictus. Suitability Index/Predator Safety Factor was assessed on Toxorhynchites splendens and Mesocyclops thermocyclopoides. The leaf extract of B. tinctoria was toxic against larval instars (I–IV) and pupae of Ae. albopictus; LC50 was 182.72 ppm (I instar), 230.99 ppm (II), 269.65 ppm (III), 321.75 ppm (IV), and 359.71 ppm (pupa). B. tinctoria-synthesized AgNPs were highly effective, with LC50 of 4.97 ppm (I instar), 5.97 ppm (II), 7.60 ppm (III), 9.65 ppm (IV), and 14.87 ppm (pupa). Both the leaf extract and AgNPs showed reduced toxicity against the mosquito natural enemies M. thermocyclopoides and T. splendens. Overall, this study firstly shed light on effectiveness of B. tinctoria-synthesized AgNPs as an eco-friendly nanopesticide, highlighting the concrete possibility to employ this newer and safer tool in arbovirus vector control programs.

  10. Ag-NP@Ge-nanotaper/Si-micropillar ordered arrays as ultrasensitive and uniform surface enhanced Raman scattering substrates

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Meng, Guowen; Li, Zhongbo; Huang, Zhulin; Li, Xiangdong

    2015-10-01

    Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment.Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform

  11. Irradiation with visible light enhances the antibacterial toxicity of silver nanoparticles produced by laser ablation

    NASA Astrophysics Data System (ADS)

    Ratti, Matthew; Naddeo, J. J.; Tan, Yuying; Griepenburg, Julianne C.; Tomko, John; Trout, Cory; O'Malley, Sean M.; Bubb, Daniel M.; Klein, Eric A.

    2016-04-01

    The rise of antibiotic-resistant bacteria is a rapidly growing global health concern. According to the Center for Disease Control, approximately 2 million illnesses and 23,000 deaths per year occur in the USA due to antibiotic resistance. In recent years, there has been a surge in the use of metal nanoparticles as coatings for orthopedic implants, wound dressings, and food packaging, due to their antimicrobial properties. In this report, we demonstrate that the antibacterial efficacy of silver nanoparticles (AgNPs) is enhanced with exposure to light from the visible spectrum. We find that the increased toxicity is due to augmented silver ion release and bacterial uptake. Interestingly, silver ion toxicity does not appear to depend on the formation of reactive oxygen species. Our findings provide a novel paradigm for using light to regulate the toxicity of AgNPs which may have a significant impact in the development of new antimicrobial therapeutics.

  12. Bioinspired and biocompatible carbon nanotube-Ag nanohybrid coatings for robust antibacterial applications.

    PubMed

    Nie, Chuanxiong; Yang, Ye; Cheng, Chong; Ma, Lang; Deng, Jie; Wang, Lingren; Zhao, Changsheng

    2017-03-15

    The design of self-sterilizing surfaces with favorable biocompatibility is acknowledged as an effective approach to deal with the bacterial infections of biomedical devices. In this study, we report an intriguing protocol for the large-scale fabrication of self-sterilizing and biocompatible surface film coatings by using polymer shielded silver nanoparticle loaded oxidized carbon nanotube (AgNPs@oCNT) nano-dispersions. To achieve the antibacterial coatings, the bioinspired positively charged and negatively charged AgNPs@oCNTs were alternately deposited onto substrates by spray-coating assisted layer-by-layer assembly. Then the bacterial inhibitory zones, optical density value monitoring, bacterial killing efficiency and adhesion were investigated; and all the results revealed that the AgNPs@oCNTs thin film coatings exhibited robust and long-term antibacterial activity against both Gram negative and Gram positive bacteria. Moreover, due to the shielding effects of polymer layers, the coatings showed extraordinary blood compatibility and limited toxicity against human umbilical vein endothelial cells. It is believed that the proposed large-scale fabrication of bactericidal, blood and cell compatible AgNPs@oCNT based thin film coatings will have great potential to forward novel operational pathogenic inhibition strategies to avoid undesired bacterial contaminations of biomedical implants or biological devices.

  13. Efficient continuous biosynthesis of silver nanoparticles by activated sludge micromycetes with enhanced tolerance to metal ion toxicity.

    PubMed

    Tyupa, Dmitry V; Kalenov, Sergei V; Baurina, Marina M; Yakubovich, Liubov M; Morozov, Alexander N; Zakalyukin, Ruslan M; Sorokin, Vladimir V; Skladnev, Dmitry A

    2016-12-01

    The method for producing AgNPs by granules of activated sludge micromycetes with enhanced tolerance to metal ion toxicity - Penicillium glabrum, Fusarium nivale and Fusarium oxysporum has been developed; the optimum conditions for AgNP biosynthesis being found: the Ag(+) ion concentration, duration of the contact of microbial cells with silver ions, a growth phase of microorganisms, medium composition, a рН value, mixing conditions, and also lighting intensity. The effect of Cl(-), SO4(2-) and HPO4(2-) ions binding Ag(+) ions was eliminated, that brought to significant increase of the yield of NPs. Under batch conditions, silver particles of 60-110 nanometers in size were formed with a 65% yield. It was established that the nanoparticles were covered with microbial cell membrane proteins composed up to 70% by weight of the NPs that prevented their aggregation. In addition, it was the first time stable AgNPs had been formed by continuous AgNP biosynthesis by living cells of F. oxysporum with an 80% yield for a long time.

  14. Toxicity mechanisms of ionic silver and polymer-coated silver nanoparticles with interactions of functionalized carbon nanotubes on early development stages of sea urchin.

    PubMed

    Magesky, Adriano; Pelletier, Émilien

    2015-10-01

    Exposures of aquatic organisms to multiple contaminants are likely to take place in estuarine and coastal areas and combined effects on early life stages have to be examined. Among emerging contaminants, ionic silver (Ag(+)) and silver nanoparticles (AgNps) have demonstrated contrasting effects on marine invertebrates, but their interactions with functionalized carbon nanotubes (f-SWCNTs) have not yet been investigated in details. In order to observe the impacts and understand the toxicity mechanism of Ag(+) and polymer-coated AgNps, and their combined effects with f-SWCNTs, successive development stages of embryos of sea urchin, Strongylocentrotus droebachiensis, were exposed to Ag(+), AgNps and f-SWCNTs, separately and in mixtures using moderate environmental concentrations. We also assessed long-term effects of treatments under recovery conditions. Morphological endpoints such as archenteron elongation, primary and secondary mesenchyme cells fate, pigment cells migration, spiculogenic cells and gut development indicated different effects of silver and nanosilver forms during successive development stages. Whereas Ag(+) induced vegetalization and extrusion of mesenchyme cells on early embryos; f-SWCNTs+Ag(+) strongly interfered with gut regionalization in late larvae. Sensitive blastocoelar cells got vacuolized and shapeless with AgNps, but not with mixtures with f-SWCNTs. Increased concentrations of Ag(+) and f-SWCNTs+Ag(+) led to the most disruptive effects during development, but f-SWCNTs+Ag(+) caused the highest mortality rate during the recovery period, which indicated far-reaching effects driven by f-SWCNTs and their ability to keep silver more available during exposure period.

  15. Antimicrobial wound dressing nanofiber mats from multicomponent (chitosan/silver-NPs/polyvinyl alcohol) systems.

    PubMed

    Abdelgawad, Abdelrahman M; Hudson, Samuel M; Rojas, Orlando J

    2014-01-16

    Novel hybrid nanomaterials have been developed for antimicrobial applications. Here we introduce a green route to produce antibacterial nanofiber mats loaded with silver nanoparticles (Ag-NPs, 25 nm diameter) enveloped in chitosan after reduction with glucose. The nanofiber mats were obtained from colloidal dispersions of chitosan-based Ag-NPs blended with polyvinyl alcohol. Nanofibers (150 nm average diameter and narrow size distribution) were obtained by electrospinning and cross-linked with glutaraldhyde. The effect of crosslinking on the release of silver was studied by atomic absorption spectroscopy. Antimicrobial activity was studied by the viable cell-counting; mats loaded with silver and control samples (chitosan/PVA) with different degrees of cross-linking were compared for their effectiveness in reducing or halting the growth of aerobic bacteria. The results showed superior properties and synergistic antibacterial effects by combining chitosan with Ag-NPs.

  16. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaffin, Elise; O'Connor, Ryan T.; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ˜410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods.

  17. A nanotechnology based new approach for chemotherapy of Cutaneous Leishmaniasis: TIO2@AG nanoparticles - Nigella sativa oil combinations.

    PubMed

    Abamor, Emrah Sefik; Allahverdiyev, Adil M

    2016-07-01

    Since toxicity and resistance are the major drawbacks of current antileishmanial drugs, studies have been recently focused on combination therapy in fight against leishmaniasis. Combination therapy generally provides opportunity to decrease toxicity of applied agents and enhance their antimicrobial performance. Moreover, this method can be effective in preventing drug resistance. Highly antileishmanial effects of silver doped titanium dioxide nanoparticles (TiAgNps) and Nigella sativa oil were demonstrated in previous studies. However, toxicity is still an important factor preventing use of these molecules in clinic. By considering high antileishmanial potential of each agent and basic principles of combination therapy, we propose that use of combinations including non-toxic concentrations of TiAgNps and N. sativa oil may compose more effective and safer formulations against Leishmania parasites. Therefore, the main goal of the present study was to investigate antileishmanial effects of non-toxic concentrations of TiAgNps and Nigella sativa oil combinations on promastigote and amastigote-macrophage culture systems and also to develop nanotechnology based new antileishmanial strategies against Cutaneous Leishmaniasis. Numerous parameters such as proliferation, metabolic activity, apoptosis, amastigote-promastigote conversion, infection index analysis and nitric oxide production were used to detect antileishmanial efficacies of combinations. Investigated all parameters demonstrated that TiAgNps-N. sativa oil combinations had significant antileishmanial effect on each life forms of parasites. Tested combinations were found to decrease proliferation rates of Leishmania tropica promastigotes in a range between 1,5-25 folds and metabolic activity values between 2 and 4 folds indicating that combination applications lead to virtually inhibition of promastigotes and elimination of parasites were directly related to apoptosis manner. TiAgNps-N. sativa combinations also

  18. 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.

  19. Comparison of the toxicity of silver, gold and platinum nanoparticles in developing zebrafish embryos.

    PubMed

    Asharani, P V; Lianwu, Yi; Gong, Zhiyuan; Valiyaveettil, Suresh

    2011-03-01

    Nanoparticles have diverse applications in electronics, medical devices, therapeutic agents and cosmetics. While the commercialization of nanoparticles is rapidly expanding, their health and environmental impact is not well understood. Toxicity assays of silver, gold, and platinum nanoparticles, using zebrafish embryos to study their developmental effects were carried out. Gold (Au-NP, 15-35 nm), silver (Ag-NP, 5-35 nm) and platinum nanoparticles (Pt-NP, 3-10 nm) were synthesized using polyvinyl alcohol (PVA) as a capping agent. Toxicity was recorded in terms of mortality, hatching delay, phenotypic defects and metal accumulation. The addition of Ag-NP resulted in a concentration-dependant increase in mortality rate. Both Ag-NP and Pt-NP induced hatching delays, as well as a concentration dependant drop in heart rate, touch response and axis curvatures. Ag-NP also induced other significant phenotypic changes including pericardial effusion, abnormal cardiac morphology, circulatory defects and absence or malformation of the eyes. In contrast, Au-NP did not show any indication of toxicity. Uptake and accumulation of nanoparticles in embryos was confirmed by inductively coupled plasma optical emission spectroscopy (ICP-OES), which revealed detectable levels in embryos within 72 hpf. Ag-NP and Au-NP were taken up by the embryos in relatively equal amounts whereas lower Pt concentrations were observed in embryos exposed to Pt-NP. This was probably due to the small size of the Pt nanoparticles compared to Ag-NP and Au-NP, thus resulting in fewer metal atoms being retained in the embryos. Among the nanoparticles studied, Ag-NPs were found to be the most toxic and Au-NPs the non-toxic. The toxic effects exhibited by the zebrafish embryos as a consequence of nanoparticle exposure, accompanied by the accumulation of metals inside the body calls for urgent further investigations in this field.

  20. Ag/FeCo/Ag core/shell/shell magnetic nanoparticles with plasmonic imaging capability.

    PubMed

    Takahashi, Mari; Mohan, Priyank; Nakade, Akiko; Higashimine, Koichi; Mott, Derrick; Hamada, Tsutomu; Matsumura, Kazuaki; Taguchi, Tomohiko; Maenosono, Shinya

    2015-02-24

    Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-L-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

  1. Heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst with enhanced photocatalytic activity and stability under visible light

    NASA Astrophysics Data System (ADS)

    Wang, Wan-Sheng; Du, Hong; Wang, Rui-Xia; Wen, Tao; Xu, An-Wu

    2013-03-01

    A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high efficiencies of the photocatalytic activity and the improved stability. With the assistance of Ag3PO4/AgBr/Ag heterostructures, only 8 min and 12 min are taken to completely decompose MO and MB molecules under visible-light irradiation, respectively. Furthermore, the photodegradation rate does not show an obvious decrease during ten successive cycles, indicating that our heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts are extremely stable under visible-light irradiation.A heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalyst was prepared by a rational in situ ion exchange reaction between Ag3PO4 micro-cubes and Br- in aqueous solution followed by photoreduction. The photocatalytic activities of obtained photocatalysts were measured by the degradation of methyl orange (MO) and methylene blue (MB) under visible light irradiation (λ >= 400 nm). Compared to AgBr/Ag, Ag3PO4/AgBr heterocrystals and pure Ag3PO4 crystals, the heterostructured Ag3PO4/AgBr/Ag plasmonic photocatalysts exhibit much higher photocatalytic activity and stability. This enhanced photocatalytic activity suggests that the synergetic effects of the heterostructured Ag3PO4/AgBr/Ag and the strong SPR of Ag NPs on the surface result in the high

  2. The applicability of conventional cytotoxicity assays to predict safety/toxicity of mesoporous silica nanoparticles, silver and gold nanoparticles and multi-walled carbon nanotubes.

    PubMed

    Mannerström, Marika; Zou, Jing; Toimela, Tarja; Pyykkö, Ilmari; Heinonen, Tuula

    2016-12-01

    Developing new, validated methods for screening of the effects of nanomaterials is a huge and expensive task. It is therefore necessary to try to employ already existing and validated methods, developed for chemicals. In the present study cytotoxicity of gold (Au) and silver (Ag) nanoparticles (NP), two different mesoporous silica nanoparticles (MSNP), and multi-walled carbon nanotubes (MWCNT) were investigated in BALB/c 3T3 fibroblasts, NR8383 macrophages, and U937 monocytes using standard assays, namely WST-1 and NRU. In addition, preliminary attempts were made to investigate ENM-mediated effects on cell motility as a potential end point for NP toxicity. AgNPs were most toxic to BALB/c 3T3 fibroblasts while other ENMs were insignificantly toxic. NR8383 macrophages were most sensitive cells, as in addition to AgNPs, also MWCNTs were toxic to NR8383 cells. AgNP was toxic also to U937 cells, other ENMs had minor effect. Different media resulted in different-sized aggregates of the same ENMs. AgNP inhibited BALB/c motility most, whereas NR8383 motility was inhibited most by MWCNTs. In conclusion, conventional cytotoxicity assays are better suited to rank the order of toxicity of different nanoparticles instead of producing accurate IC50 data. Moreover, using immune cells, especially macrophages together with fibroblasts, would bring more relevant predictions of ENM cytotoxicity as immune cells may discover cytotoxicity that is not captured by BALB/c 3T3 cells alone.

  3. Silver nanoparticles exhibit size-dependent differential toxicity and induce expression of syncytin-1 in FA-AML1 and MOLT-4 leukaemia cell lines.

    PubMed

    Alqahtani, Sultan; Promtong, Pawika; Oliver, Anthony W; He, Xiaotong T; Walker, Thomas D; Povey, Andrew; Hampson, Lynne; Hampson, Ian N

    2016-11-01

    Human endogenous retrovirus (HERV) sequences make up ~8% of the human genome and increased expression of some HERV proteins has been observed in various pathologies including leukaemia and multiple sclerosis. However, little is known about the function of these HERV proteins or environmental factors which regulate their expression. Silver nanoparticles (AgNPs) are used very extensively as antimicrobials and antivirals in numerous consumer products although their effect on the expression of HERV gene products is unknown. Cell proliferation and cell toxicity assays were carried out on human acute T lymphoblastic leukaemia (MOLT-4) and Fanconi anaemia associated acute myeloid leukaemia (FA-AML1) cells treated with two different sizes of AgNPs (7nm and 50nm diameter). Reverse-transcriptase polymerase chain reaction and western blotting were then used to the assess expression of HERV-W syncytin-1 mRNA and protein in these cells. FA-AML1 cells were more sensitive overall than MOLT-4 to treatment with the smaller 7nm sized AgNp's being the most toxic in these cells. MOLT-4 cell were more resistant and showed no evidence of differential toxicity to the different sized particles. Syncytin-1 mRNA and protein were induced by both 7 and 50nm AgNPs in both cell types yet with different kinetics. In summary, the observation that AgNPs induce expression of syncytin-1 in FA-AML1 and MOLT-4 cells at doses as little as 5 µg/ml is grounds for concern since this protein is up-regulated in both malignant and neurodegenerative diseases. Considering the widespread use of AgNPs in the environment it is clear that their ability to induce syncytin-1 should be investigated further in other cell types.

  4. 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.

  5. Cytotoxicity of Au, ZnO and SiO₂ NPs using in vitro assays with mussel hemocytes and gill cells: Relevance of size, shape and additives.

    PubMed

    Katsumiti, Alberto; Arostegui, Inmaculada; Oron, Miriam; Gilliland, Douglas; Valsami-Jones, Eugenia; Cajaraville, Miren P

    2016-01-01

    Metal-bearing nanoparticles (NPs) possess unique physico-chemical characteristics that make them useful for an increasing number of industrial products and applications, but could also confer them a higher toxicity due to their higher reactivity compared to bulk forms of the same materials. There is a considerable interest in the use of in vitro techniques in environmentally relevant species, such as marine mussels, to evaluate NPs toxicity. In the present work, mussel hemocytes and gill cells were used to assess the potential toxic effects of Au, ZnO and SiO2 NPs with different sizes and shapes in parallel with their respective ionic and bulk forms and additives used in the NPs preparations. Cytotoxicity (neutral red and MTT assays) was screened at a wide range of concentrations, and LC50 values were calculated. Uptake of fluorescently labeled SIO2 NPs of 27 nm by hemocytes was also investigated. Au, ZnO and SiO2 NPs were less toxic than the corresponding ionic forms but more toxic than the bulk forms. ZnO NPs were the most toxic NPs tested which could be related with their capacity to release free ions. SiO2 NPs were not taken up by hemocytes and were not toxic to either hemocytes or gill cells. Size-dependent toxicity was found for Au NPs. Shape influenced the cytotoxicity of ZnO NPs. Finally, the presence of the additives Na-citrate and Ecodis P90 contributed to the toxicity of Au and ZnO NPs, respectively. As a general conclusion, solubility appears to play a key role in NPs toxicity to mussel cells.

  6. Fabrication of small-sized silver NPs/graphene sheets for high-quality surface-enhanced Raman scattering.

    PubMed

    Zhao, Hong; Fu, Honggang; Zhao, Tianshou; Wang, Lei; Tan, Taixing

    2012-06-01

    In this paper, small-sized and highly dispersed Ag nanoparticles (NPs) supported on graphene nanosheets are fabricated via a strategy for etching a copper template with Ag(+). Firstly, big-sized Cu NPs are supported on graphene, and then the small-sized and highly dispersed Ag NPs are supported on graphene by replacement reaction, mainly making use of graphene passing electrons between Cu and Ag(+). The graphene used in the experiment is prepared by in situ self-generating template and has good dispersion, excellent crystallinity and little defects. Thus, in the process of Ag/graphene synthesis, there is no any intervention of surfactant, which ensures that SERS activity sites have not been passivated. And, the little defects of graphene benefit the excellent conductivity of graphene and ensured the replacement reaction between Cu and Ag(+). The obtained material exhibits significant high-quality and distinctive SERS activity. Especially, a serial new peak of p-aminothiophenol (PATP) is observed, this is suggested two reasons: one is "surface geometry" of the PATP on small-sized Ag NPs and another is the charge-transfer between Ag and graphene.

  7. Effect of Ag Templates on the Formation of Au-Ag Hollow/Core-Shell Nanostructures.

    PubMed

    Tsai, Chi-Hang; Chen, Shih-Yun; Song, Jenn-Ming; Haruta, Mitsutaka; Kurata, Hiroki

    2015-12-01

    Au-Ag alloy nanostructures with various shapes were synthesized using a successive reduction method in this study. By means of galvanic replacement, twined Ag nanoparticles (NPs) and single-crystalline Ag nanowires (NWs) were adopted as templates, respectively, and alloyed with the same amount of Au(+) ions. High angle annular dark field-scanning TEM (HAADF-STEM) images observed from different rotation angles confirm that Ag NPs turned into AuAg alloy rings with an Au/Ag ratio of 1. The shifts of surface plasmon resonance and chemical composition reveal the evolution of the alloy ring formation. On the other hand, single-crystalline Ag NWs became Ag@AuAg core-shell wires instead of hollow nanostructure through a process of galvanic replacement. It is proposed that in addition to the ratio of Ag templates and Au ion additives, the twin boundaries of the Ag templates were the dominating factor causing hollow alloy nanostructures.

  8. Hierarchically Structured Recommender System for Improving NPS

    ERIC Educational Resources Information Center

    Kuang, Jieyan

    2016-01-01

    Net Promoter System (NPS) is well known as an evaluation measure of the growth engine of big companies in the business area. The ultimate goal of my research is to build an action rules and meta-actions based recommender system for improving NPS scores of 34 companies (clients) dealing with similar businesses in the US and Canada. With the given…

  9. Neurotoxicity and biochemical responses in the earthworm Pheretima hawayana exposed to TiO2NPs.

    PubMed

    Khalil, Abdelmonem M

    2015-12-01

    Serious concerns have been expressed about potential risks of manufactured TiO2NPs. In this research, toxicity of nanoparticulate and bulk TiO2 were examined to the earthworm Pheretima hawayana. The 24-h median lethal concentration (LC50) and sublethal endpoints were assessed. Both NPs and their bulk counterparts were toxic. The 24-h LC50 for TiO2NPs (145.36 mg kg(-1)) was highly toxic than that of bulk TiO2 (357.77 mg kg(-1)). The aim of the present work is to evaluate the suitability of P. hawayana and its biochemical responses to be used as a bioindicator organism and biomarkers of TiO2 toxicity. Earthworms were exposed to three sublethal concentrations of TiO2NPs (1, 10 and 100 µg kg(-1)) for 28 days to test acetylcholinesterase (AChE), antioxidant enzymes (superoxide dismutase: SOD and catalase: CAT) activities and MDA content. The response of the antioxidant enzymes combined with AChE inhibition and MDA accumulation indicated that TiO2NPs could induce significant impairments to the earthworms at the actual environment tested concentrations. The results pointed out the high sensitivity of the antioxidant and oxidative stress related responses to TiO2NPs exposure, demonstrating their usefulness in environmental monitoring and risk assessment. The study highlights also the usefulness of earthworm P. hawayana as potential bioindicator species for assessing the risk of nanoparticles environmental contamination.

  10. Surface-enhanced Raman spectroscopy for DNA detection by the self-assembly of Ag nanoparticles onto Ag nanoparticle-graphene oxide nanocomposites.

    PubMed

    Lin, Tsung-Wu; Wu, Hong-Yi; Tasi, Ting-Ti; Lai, Ying-Huang; Shen, Hsin-Hui

    2015-07-28

    A novel surface-enhanced Raman scattering (SERS) sensing system which operates by the self-assembly of Ag nanoparticles (AgNPs) onto the nanocomposite of AgNPs and graphene oxide (AgNP-GO) in the presence of two complementary DNAs has been developed. In this system, AgNP-GO serves as a SERS-active substrate. The AgNPs with the modification of non-fluorescent 4-mercaptobenzoic acid (4-MBA) act as highly efficient Raman probes for DNA hybridization. When probe DNAs on AgNP-GO are complementary to target DNAs on AgNPs functionalized with 4-MBA, the DNA hybridization occurring directs the self-assembly of AgNPs onto AgNP-GO, leading to the creation of SERS hot spots. Due to the fact that partial 4-MBA molecules are located in the region of the hot spots, their SERS signals are greatly enhanced, indicating successful DNA hybridization. It is noteworthy that the size of AgNPs contributes significantly to the enhancement of SERS activity. The detection limit of the target DNAs at the pM level can be achieved through the self-assembly of large sized AgNPs onto AgNP-GO. More importantly, the AgNP-AgNP-GO system shows reproducible SERS signals in proportion to the logarithm of the target DNA concentrations spanning from 10(-6) to 10(-12) M and the excellent capability for multiplex DNA detection.

  11. Photoluminescence Behaviour of Sm3+ Ions in presence of Ag Nanoparticles in Methanol

    NASA Astrophysics Data System (ADS)

    Dehingia, N.; Gogoi, P.; Boruah, A.; Kakoti, D.; Rajkonwar, N.; Dutta, P.

    2016-10-01

    In the present work, capped Ag NPs prepared by reduction of Ag (NO3)3 by Dimethyl Formamide is doped with Sm3+ in methanol and its photoluminescence behavior is studied. Significant modifications of the Sm3+ ions’ emission as well as quantum yield, were observed with the concentration of Ag NPs. Local field enhancement induced by neutral Ag NPs were found to be responsible for enhancement in efficiency of the Sm3+ ions.

  12. Behavioural toxicity assessment of silver ions and nanoparticles on zebrafish using a locomotion profiling approach.

    PubMed

    Ašmonaitė, Giedrė; Boyer, Scott; Souza, Karine Bresolin de; Wassmur, Britt; Sturve, Joachim

    2016-04-01

    Zebrafish (Danio rerio) is not only a widely used species in the Fish Embryo Toxicity (FET) test but also an emerging model in behavioural ecotoxicology. By using automatic behaviour tracking technology, locomotion of developing zebrafish (ZF) larvae can be accurately recorded and potentially used in an ecotoxicological context to detect toxicant-induced behavioural alterations. In this study, we explored if and how quantitative locomotion data can be used for sub-lethal toxicity testing within the FET framework. We exposed ZF embryos to silver ions and nanoparticles, which previously have been reported to cause neurodevelopmental toxicity and behavioural retardation in early-life stages of ZF. Exposure to a broad range of silver (Ag(+) and AgNPs) concentrations was conducted, and developmental toxicity was assessed using FET criteria. For behavioural toxicity assessment, locomotion of exposed ZF eleutheroembryos (120hpf) was quantified according to a customised behavioural assay in an automatic video tracking system. A set of repeated episodes of dark/light stimulation were used to artificially stress ZF and evoke photo-motor responses, which were consequently utilized for locomotion profiling. Our locomotion-based behaviour profiling approach consisted of (1) dose-response ranking for multiple and single locomotion variables; (2) quantitative assessment of locomotion structure; and (3) analysis of ZF responsiveness to darkness stimulation. We documented that both silver forms caused adverse effects on development and inhibited hatchability and, most importantly, altered locomotion. High Ag(+) and AgNPs exposures significantly suppressed locomotion and a clear shift in locomotion towards inactivity was reported. Additionally, we noted that low, environmentally relevant Ag(+) concentrations may cause subordinate locomotive changes (hyperactivity) in developing fish. Overall, it was concluded that our locomotion-based behaviour-testing scheme can be used jointly

  13. Intranasally Administered Neuropeptide S (NPS) Exerts Anxiolytic Effects Following Internalization Into NPS Receptor-Expressing Neurons

    PubMed Central

    Ionescu, Irina A; Dine, Julien; Yen, Yi-Chun; Buell, Dominik R; Herrmann, Leonie; Holsboer, Florian; Eder, Matthias; Landgraf, Rainer; Schmidt, Ulrike

    2012-01-01

    Experiments in rodents revealed neuropeptide S (NPS) to constitute a potential novel treatment option for anxiety diseases such as panic and post-traumatic stress disorder. However, both its cerebral target sites and the molecular underpinnings of NPS-mediated effects still remain elusive. By administration of fluorophore-conjugated NPS, we pinpointed NPS target neurons in distinct regions throughout the entire brain. We demonstrated their functional relevance in the hippocampus. In the CA1 region, NPS modulates synaptic transmission and plasticity. NPS is taken up into NPS receptor-expressing neurons by internalization of the receptor–ligand complex as we confirmed by subsequent cell culture studies. Furthermore, we tracked internalization of intranasally applied NPS at the single-neuron level and additionally demonstrate that it is delivered into the mouse brain without losing its anxiolytic properties. Finally, we show that NPS differentially modulates the expression of proteins of the glutamatergic system involved inter alia in synaptic plasticity. These results not only enlighten the path of NPS in the brain, but also establish a non-invasive method for NPS administration in mice, thus strongly encouraging translation into a novel therapeutic approach for pathological anxiety in humans. PMID:22278093

  14. Phyllanthus emblica seed extract mediated synthesis of PdNPs against antibacterial, heamolytic and cytotoxic studies.

    PubMed

    Dinesh, Murugesan; Roopan, Selvaraj Mohana; Selvaraj, Chinnadurai Immanuel; Arunachalam, Prabhakarn

    2017-02-01

    Ecofriendly synthesis of Palladium nanoparticles (PdNPs) were achieved using Phyllanthus emblica (P. emblica) seeds as reducing agent. Further the ecofriendly synthesized PdNPs were subjected for various analytical techniques like UV-Vis, FT-IR, XRD, Zeta potential, SEM and TEM. The results indicated that green synthesized PdNPs were spherical in shape with average particle size of 28±2nm with moderate stability. Further the synthesized PdNPs and extract were subjected for its antibacterial studies against various disease causing pathogens by agar well diffusion method. Seed extract resulted in 8.9±1.46mm against B. subtilis and PdNPs showed 9.6±1.10mm against S. aureus and synthesized PdNPs and extract were tested for hemolytic which resulted in 20% and 10% respectively. Toxicity studies were done against Artemia salina (A. salina). The LC50 value of green synthesized P. emblica capped PdNPs and the P. emblica seed extract were found to be less toxic for A. salina with a value of 1.00μg/mL and 1.25μg/mL. In addition samples were checked for in vitro cytotoxicity assays on HeLa cell lines.

  15. A Review of Molecular Mechanisms Involved in Toxicity of Nanoparticles

    PubMed Central

    Khalili Fard, Javad; Jafari, Samira; Eghbal, Mohammad Ali

    2015-01-01

    In recent decades, the use of nanomaterials has received much attention in industrial and medical fields. However, some reports have mentioned adverse effects of these materials on the biological systems and cellular components. There are several major mechanisms for cytotoxicity of nanoparticles (NPs) such as physicochemical properties, contamination with toxic element, fibrous structure, high surface charge and radical species generation. In this review, a brief key mechanisms involved in toxic effect of NPs are given, followed by the in vitro toxicity assays of NPs and prooxidant effects of several NPs such as carbon nanotubes, titanium dioxide NPs, quantum dots, gold NPs and silver NPs. PMID:26819915

  16. Effects of ionization on the toxicity of silver nanoparticles to Japanese medaka (Oryzias latipes) embryos.

    PubMed

    Lee, Byoung-Cheun; Kim, Jungkon; Cho, Jae-Gu; Lee, Jae-Woo; Duong, Cuong N; Bae, Eunjoo; Yi, Jongheop; Eom, Ig-Chun; Choi, Kyunghee; Kim, Pilje; Yoon, Junheon

    2014-01-01

    Increase in the use of manufactured nanomaterials (NMs) has led to concerns about the environmental impacts. Especially, hazard of metal-based NMs is more severe due to ions released from surface by water quality parameters and physicochemical properties after entering into the water environment. However, little is known about the effects of ionization on the toxicity of metal-based NMs in the water environment. To address this question, we prepared the suspensions of silver nanoparticles (AgNP) at 25 μg L(-1) containing different concentrations of Ag(+) (5, 10, 20, 45, and 75% Ag(+) to total Ag), and evaluated their toxicity to Japanese medaka (Oryzias latipes) embryos. Higher Ag(+) ratios in the AgNP suspension, suggesting the lower number of particles, led to the higher adverse effects on embryos and sac-fries. In addition, histopathology analysis revealed that AgNPs penetrated through chorion of eggs and skin membrane, and were distributed into the tissues. The results imply that the ionization could decrease the toxicity of metal-based NMs in the water environment.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  18. In vitro cytotoxicity evaluation of porous TiO₂-Ag antibacterial coatings for human fetal osteoblasts.

    PubMed

    Necula, B S; van Leeuwen, J P T M; Fratila-Apachitei, L E; Zaat, S A J; Apachitei, I; Duszczyk, J

    2012-11-01

    Implant-associated infections (IAIs) may be prevented by providing antibacterial properties to the implant surface prior to implantation. Using a plasma electrolytic oxidation (PEO) technique, we produced porous TiO₂ coatings bearing various concentrations of Ag nanoparticles (Ag NPs) (designated as 0 Ag, 0.3 Ag and 3.0 Ag) on a Ti-6Al-7Nb biomedical alloy. This study investigates the cytotoxicity of these coatings using a human osteoblastic cell line (SV-HFO) and evaluates their bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA). The release of Ag and the total amount of Ag in the coatings were determined using a graphite furnace atomic absorption spectrometry technique (GF-AAS) and flame-AAS, respectively. Cytotoxicity was evaluated using the AlamarBlue assay coupled with the scanning electron microscopy (SEM) observation of seeded cells and by fluorescence microscopy examination of the actin cytoskeleton and nuclei after 48 h of incubation. Antibacterial activity was assessed quantitatively using a direct contact assay. AlamarBlue viability assay, SEM and fluorescence microscopy observation of the SV-HFO cells showed no toxicity for 0 Ag and 0.3 Ag specimens, after 2, 5 and 7 days of culture, while 3.0 Ag surfaces appeared to be extremely cytotoxic. All Ag-bearing surfaces had good antibacterial activity, whereas Ag-free coatings showed an increase in bacterial numbers. Our results show that the 0.3 Ag coatings offer conditions for optimum cell growth next to antibacterial properties, which makes them extremely useful for the development of new antibacterial dental and orthopedic implants.

  19. Study of Silymarin and Vitamin E Protective Effects on Silver Nanoparticle Toxicity on Mice Liver Primary Cell Culture.

    PubMed

    Faedmaleki, Firouz; Shirazi, Farshad H; Ejtemaeimehr, Shahram; Anjarani, Soghra; Salarian, Amir-Ahmad; Ahmadi Ashtiani, Hamidreza; Rastegar, Hossein

    2016-02-01

    Nanotechnology is a most promising field for generating new applications in medicine, although, only few nano products are currently in use for medical purposes. A most prominent nanoproduct is nanosilver. Nano-silver has biological properties which are significant for consumer products, food technology, textiles, and medical applications (e.g. wound care products, implantable medical devices, in diagnosis, drug delivery, and imaging). For their antibacterial activity, silver nanoparticles (Ag NPs) are largely used in various commercially available products. The use of nano-silver is becoming more and more widespread in medicine and related applications, and due to its increasing exposure, toxicological and environmental issues need to be raised. Cytotoxicity induced by silver nanoparticles (AgNPs) and the role that oxidative stress plays in this process were demonstrated in human hepatoma cells AgNPs agglomerated in the cytoplasm and nuclei of treated cells, and they induced intracellular oxidative stress. AgNP reduced ATP content of the cell and caused damage to mitochondria and increased production of reactive oxygen species (ROS) in a dose-dependent manner. Silymarin was known as a hepatoprotective agent that is used in the treatment of hepatic diseases including viral hepatitis, alcoholic liver diseases, Amanita mushroom poisoning, liver cirrhosis, toxic and drug-induced liver diseases. It promotes protein synthesis, helps in regenerating liver tissue, controls inflammation, enhances glucuronidation, and protects against glutathione depletion. Vitamin E is a well-known antioxidant and has hepatoprotective effect in liver diseases. In this study, we investigated the cytotoxic effects of Ag NPs on primary liver cells of mice. Cell viability (cytotoxicity) was examined with MTT assay after primary liver cells of mice exposure to AgNPs at 1, 10, 50, 100, 150, 200, 400 ppm for 24h. AgNPs caused a concentration- dependent decrease of cell viability (IC50 value = 121

  20. Synthesis, characterization, and application of Fe3O4/Ag magnetic composites for mercury removal from water

    NASA Astrophysics Data System (ADS)

    Elhouderi, Z. A.; Beesley, D. P.; Nguyen, T. T.; Lai, P.; Sheehan, K.; Trudel, S.; Prenner, E.; Cramb, D. T.; Anikovskiy, M.

    2016-04-01

    Engineered nanocomposites (NCs) have recently emerged as materials of great scientific and technological interest. In these materials, different components are combined to yield a nanoentity with desired properties not afforded by the constituent materials. Designing novel NCs and synthetic routes that enable controlling the size and functionalities remains an active area of research. Here, we present a two-step method of synthesizing Ag-Fe3O4 NCs with tunable sizes. Unlike previously reported structures, the prepared NCs do not have a familiar core-shell architecture. Instead, small Fe3O4 nanoparticles (NPs) are embedded in a larger silver matrix. The superparamagnetic Fe3O4 NPs endow the NC with magnetic properties, enabling easy separation from solution. The degree of the NC response to an external magnetic field can be controlled by varying the concentration of Fe3O4 NPs during the synthesis. The Ag matrix serves to protect the embedded Fe3O4 NPs from degradation and can be used for further functionalization of the NCs with different sulfhydryl containing linkers. To demonstrate utility, we show how decorating the outer layer of the Ag NC with diphenyl-4,4‧-dithiol transforms the NCs into a water purifying system capable of sequestering highly toxic Hg2+ ions from solution magnetically.

  1. 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.

  2. Antibacterial carboxymethyl cellulose/Ag nanocomposite hydrogels cross-linked with layered double hydroxides.

    PubMed

    Yadollahi, Mehdi; Namazi, Hassan; Aghazadeh, Mohammad

    2015-08-01

    This paper deals with the preparation of antibacterial nanocomposite hydrogels through the combination of carboxy methyl cellulose (CMC), layered double hydroxides (LDH), and silver nanoparticles (AgNPs). CMC-LDH hydrogels were prepared by intercalating CMC into different LDHs. Then, Ag/CMC-LDH nanocomposite hydrogels were prepared through in situ formation of AgNPs within the CMC-LDHs. XRD analysis confirmed the intercalating CMC into the LDH sheets and formation of intercalated structures, as well as formation of AgNPs within the CMC-LDHs. SEM and TEM micrographs indicated well distribution of AgNPs within the Ag/CMC-LDHs. The prepared hydrogels showed a pH sensitive swelling behavior. The Ag/CMC-LDH nanocomposite hydrogels have rather higher swelling in different aqueous solutions in comparison with CMC-LDHs. The antibacterial activity of CMC-LDHs increased considerably after formation of AgNPs and was stable for more than one month.

  3. A facile and green strategy for the synthesis of Au, Ag and Au-Ag alloy nanoparticles using aerial parts of R. hypocrateriformis extract and their biological evaluation.

    PubMed

    Godipurge, S S; Yallappa, S; Biradar, Naveen J; Biradar, J S; Dhananjaya, B L; Hegde, Gajanan; Jagadish, K; Hegde, Gurumurthy

    2016-12-01

    A facile and green strategy is reported here to synthesize gold (Au), silver (Ag) and gold-silver (Au-Ag) alloy nanoparticles (NPs) through bio-reduction reactions of aqueous corresponding metal precursors mediated by extracts of aerial parts of R. hypocrateriformis, which act as both reducing and stabilizing agents, under microwave irradiation. UV-vis spectrophotometer, XRD, FT-IR, FESEM/TEM, TGA and EDAX analysis were used to characterize the obtained NPs. The formation of NPs is evident from their surface plasmon resonance peak observed at λmax=∼550, 450 and 500nm for Au, Ag and Au-Ag alloy NPs respectively. XRD pattern revealed that fcc structure, while FT-IR spectra signify the presence of phytochemicals adsorbed on NPs. Such a biofunctionalized NPs were characterized by their weight loss, 30% due to thermal degradation of plant phytochemicals observed in TG analysis. The spherical shape of Au, Ag and Au-Ag alloy NPs (∼10-50nm) is observed by FE-SEM/TEM images. EDAX analysis confirms the expected elemental composition. Moreover, these NPs showed enhanced antimicrobial, antioxidant, and anticancer activities, though it is more pronounced for Au-Ag alloy NPs, which is due to the combining effect of phytochemicals, Au and Ag metals. Thus, the biosynthesized NPs could be applied as effective growth inhibitors for various biomedical applications.

  4. 3D silk fibroin scaffold incorporating titanium dioxide (TiO2) nanoparticle (NPs) for tissue engineering.

    PubMed

    Kim, Jung-Ho; Sheikh, Faheem A; Ju, Hyung Woo; Park, Hyun Jung; Moon, Bo Mi; Lee, Ok Joo; Park, Chan Hum

    2014-07-01

    The present study deals with fabrication of scaffolds composing of silk fibroin and TiO2 NPs fabricated using a salt-leaching process. At first instance, the TiO2 NPs were prepared by using sol-gel synthesis, affording to have average diameter of 77±21μm. Furthermore, the aqueous solutions of silk fibroin were mixed with 0.2%, 2.0% and 4.0% of TiO2 NPs and salt-leaching process was introduced which resulted in creation of porous scaffolds modified with TiO2 NPs. The presence of TiO2 NPs in scaffolds was confirmed by VP-FE-SEM-EDS, TGA and XRD. The presence of TiO2 NPs influenced in decrease in pore size and swelling behavior of composite scaffolds. The resultant mechanical property of scaffolds was improved upon the introduction of TiO2 NPs. Moreover, cell cytotoxicity results for 1, 3 and 7 days; revealed no toxic behavior to osteoblasts. However, a mild toxicity to NIH 3T3 fibroblasts was observed with the scaffolds containing 4.0% TiO2 NPs. The cell fixation results from 1 and 7 days of incubation indicated the attachment, spreading and subsequent proliferation of fibroblasts. However, these findings were independent to the amount of TiO2 NPs in scaffolds.

  5. Synthesis of multifunctional Ag@Au@phenol formaldehyde resin particles loaded with folic acids for photothermal therapy.

    PubMed

    Yang, Ping; Xu, Qi-Zhi; Jin, Sheng-Yu; Lu, Yang; Zhao, Yang; Yu, Shu-Hong

    2012-07-23

    Multifunctional Ag@Au@ phenol formaldehyde resin (PFR) particles loaded with folic acids (FA) have been designed for killing tumor cells through photothermy conversion under the irradiation of near-infrared (NIR) light. Possessing the virtue of good fluorescence, low toxicity, and good targeting, the nanocomposite consists of an Ag core, an Au layer, a PFR shell, and folic acids on the PFR shell. The Ag@PFR core-shell structure can be prepared with a simple hydrothermal method after preheating. We then filled the PFR shell with a layer of Au by heating and modified the shell with polyelectrolyte to change its surface charge state. To capture tumor cells actively, FA molecules were attached onto the surface of the Ag@Au@PFR particles in the presence of 1-ethyl-3-(3-dimethly aminopropyl) carbodiimide (EDAC) and N-hydroxysuccinimide (NHS). Owing to the excellent property of Au NPs and Ag NPs as photothermal conversion agents, the Ag@Au@ PFR@FA particles can be utilized to kill tumor cells when exposed to NIR light.

  6. Bimetallic non-alloyed NPs for improving the broadband optical absorption of thin amorphous silicon substrates

    PubMed Central

    2014-01-01

    We propose the use of bimetallic non-alloyed nanoparticles (BNNPs) to improve the broadband optical absorption of thin amorphous silicon substrates. Isolated bimetallic NPs with uniform size distribution on glass and silicon are obtained by depositing a 10-nm Au film and annealing it at 600°C; this is followed by an 8-nm Ag film annealed at 400°C. We experimentally demonstrate that the deposition of gold (Au)-silver (Ag) bimetallic non-alloyed NPs (BNNPs) on a thin amorphous silicon (a-Si) film increases the film's average absorption and forward scattering over a broad spectrum, thus significantly reducing its total reflection performance. Experimental results show that Au-Ag BNNPs fabricated on a glass substrate exhibit resonant peaks at 437 and 540 nm and a 14-fold increase in average forward scattering over the wavelength range of 300 to 1,100 nm in comparison with bare glass. When deposited on a 100-nm-thin a-Si film, Au-Ag BNNPs increase the average absorption and forward scattering by 19.6% and 95.9% compared to those values for Au NPs on thin a-Si and plain a-Si without MNPs, respectively, over the 300- to 1,100-nm range. PMID:24725390

  7. Ag-nanoparticle-decorated Ge nanocap arrays protruding from porous anodic aluminum oxide as sensitive and reproducible surface-enhanced Raman scattering substrates.

    PubMed

    Liu, Jing; Meng, Guowen; Li, Xiangdong; Huang, Zhulin

    2014-11-25

    We report on the fabrication of Ag nanoparticle (Ag NP) decorated germanium (Ge) nanocap (Ag-NPs@Ge-nanocap) arrays protruding from highly ordered porous anodic aluminum oxide (AAO) template as highly sensitive and uniform surface-enhanced Raman scattering (SERS) substrates. The hybrid SERS substrates are fabricated via a combinatorial process of AAO template-assisted growth of Ge nanotubes with each tube having a hemispherical nanocap on the AAO pore bottom, wet chemical etching of the remaining aluminum and the AAO barrier layer to expose the Ge nanocaps, and sputtering Ag NPs on the Ge nanocap arrays. Because sufficient SERS "hot spots" are created from the electromagnetic coupling among the Ag NPs on the Ge nanocap and the highly ordered Ge nanocap arrays also have semiconducting chemical supporting enhancement, the hybrid SERS substrates have high SERS sensitivity and good signal reproducibility. Using the hybrid SERS substrates, Rhodamine 6G with a concentration down to 10(-11) M is identified, and one congener of highly toxic polychlorinated biphenyls with a concentration as low as 10(-6) M is also recognized, showing great potential for SERS-based rapid detection of organic pollutants in the environment.

  8. Effects of TiO2 NPs on Silkworm Growth and Feed Efficiency.

    PubMed

    Li, YangYang; Ni, Min; Li, FanChi; Zhang, Hua; Xu, KaiZun; Zhao, XiaoMing; Tian, JiangHai; Hu, JingSheng; Wang, BinBin; Shen, WeiDe; Li, Bing

    2016-02-01

    Silkworm (Bombyx mori) (B. mori) is an economically important insect and a model species for Lepidoptera. It has been reported that feeding of low concentrations of titanium dioxide nanoparticles (TiO2 NPs) can improve feed efficiency and increase cocoon mass, cocoon shell mass, and the ratio of cocoon shell. However, high concentrations of TiO2 NPs are toxic. In this study, we fed B. mori with different concentrations of TiO2 NPs (5, 10, 20, 40, 80, and 160 mg/L) and investigated B. mori growth, feed efficiency, and cocoon quality. We found that low concentrations of TiO2 NPs (5 and 10 mg/L) were more effective for weight gains, with significant weight gain being obtained at 72 h (P < 0.05). TiO2 NPs at 20 mg/L or higher had certain inhibitory effects, with significant inhibition to B. mori growth being observed at 48 h. The feed efficiency was significantly improved at low concentrations of 5 and 10 mg/L for 14.6 and 13.1 %, respectively (P < 0.05). All B. mori fed with TiO2 NPs showed increased cocoon mass and cocoon shell mass; at 5 and 10 mg/L TiO2 NPs, cocoon mass was significantly increased by 8.29 and 9.39 %, respectively (P < 0.05). We also found that low concentrations (5 and 10 mg/L) of TiO2 NPs promoted B. mori growth and development, improved feed efficiency, and increased cocoon production, while high concentrations (20 mg/L or higher) of TiO2 NPs showed inhibitory effect to the B. mori. Consecutive feeding of high concentrations of TiO2 NPs led to some degrees of adaptability. This study provides a reference for the research on TiO2 NPs toxicity and the basis for the development of TiO2 NPs as a feed additive for B. mori.

  9. 5-fluorouracil toxicity in the treatment of colon cancer associated with the genetic polymorphism 2846 A>G (rs67376798).

    PubMed

    González-Perera, Itamar; Gutiérrez-Nicolás, Fernando; Nazco-Casariego, Gloria J; Ramos-Díaz, Ruth; Hernández-San Gil, Raquel; Pérez-Pérez, José A; González García, Jonathan; González De La Fuente, Guillermo A

    2016-04-27

    Colorectal cancer is the second most common cancer in Europe. Most antineoplastic regimens in first-line treatment involve 5-fluorouracil or oral prodrug capecitabine, combined with other antineoplastic agents such as oxaliplatin or irinotecan. It is well known that 5-fluorouracil and capecitabine are agents that can be toxic in cases of decreased dihydropyrimidine dehydrogenase activity because this enzyme is the main limiting factor in the metabolism of both agents. In this paper, we describe the case of a patient who developed severe toxicity to 5-fluouracil and who had a mutation in the gene encoding the enzyme dihydropyrimidine dehydrogenase.

  10. 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.

  11. 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.

  12. Hydrophobic interactions increase attachment of gum Arabic- and PVP-coated Ag nanoparticles to hydrophobic surfaces.

    PubMed

    Song, Jee Eun; Phenrat, Tanapon; Marinakos, Stella; Xiao, Yao; Liu, Jie; Wiesner, Mark R; Tilton, Robert D; Lowry, Gregory V

    2011-07-15

    A fundamental understanding of attachment of surface-coated nanoparticles (NPs) is essential to predict the distribution and potential risks of NPs in the environment. Column deposition studies were used to examine the effect of surface-coating hydrophobicity on NP attachment to collector surfaces in mixtures with varying ratios of octadecylichlorosilane (OTS)-coated (hydrophobic) glass beads and clean silica (hydrophilic) glass beads. Silver nanoparticles (AgNPs) coated with organic coatings of varying hydrophobicity, including citrate, polyvinylpyrrolidone (PVP), and gum arabic (GA), were used. The attachment efficiencies of GA and PVP AgNPs increased by 2- and 4-fold, respectively, for OTS-coated glass beads compared to clean glass beads. Citrate AgNPs showed no substantial change in attachment efficiency for hydrophobic compared to hydrophilic surfaces. The attachment efficiency of PVP-, GA-, and citrate-coated AgNPs to hydrophobic collector surfaces correlated with the relative hydrophobicity of the coatings. The differences in the observed attachment efficiencies among AgNPs could not be explained by classical DLVO, suggesting that hydrophobic interactions between AgNPs and OTS-coated glass beads were responsible for the increase in attachment of surface-coated AgNPs with greater hydrophobicity. This study indicates that the overall attachment efficiency of AgNPs will be influenced by the hydrophobicity of the NP coating and the fraction of hydrophobic surfaces in the environment.

  13. 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.

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

    PubMed Central

    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. PMID:28134263

  15. Ag-nanoparticle-decorated porous ZnO-nanosheets grafted on a carbon fiber cloth as effective SERS substrates.

    PubMed

    Wang, Zhiwei; Meng, Guowen; Huang, Zhulin; Li, Zhongbo; Zhou, Qitao

    2014-12-21

    We report on the large-scale synthesis of Ag-nanoparticle (Ag-NP) decorated ZnO-mesoporous-nanosheets (NSs) grafted on a flexible carbon fiber cloth (CFC), as sensitive and reproducible surface enhanced Raman scattering (SERS) substrates with excellent flexibility. The composite SERS-substrates are achieved by a combination of atomic layer deposition of ZnO-seeds on each fiber of the CFC (denoted as ZnO-seeds@CFC), chemical bath deposition and subsequent pyrolysis for the creation of ZnO-mesoporous-NSs grafted on ZnO-seeds@CFC, and ion-sputtering of Ag-NPs on the ZnO-mesoporous-NSs. As abundant SERS "hot spots" are generated from the electromagnetic coupling of the densely distributed Ag-NPs, and the semiconducting ZnO-mesoporous-NSs also have chemical supporting enhancement and distinct molecule adsorbing abilities, the composite SERS-substrates demonstrate high SERS-sensitivity with good signal reproducibility. As a trial for potential applications, the composite SERS-substrates were used to identify pesticides and highly toxic polychlorinated biphenyls (PCBs), and low concentrations down to 10(-7) M for methyl parathion and 5 × 10(-6) M for PCB-77 were reached, respectively, showing promising potential for the SERS-based rapid detection of toxic organic pollutants in the environment.

  16. Impact of bio-palladium nanoparticles (bio-Pd NPs) on the activity and structure of a marine microbial community.

    PubMed

    Nuzzo, Andrea; Hosseinkhani, Baharak; Boon, Nico; Zanaroli, Giulio; Fava, Fabio

    2017-01-01

    Biogenic palladium nanoparticles (bio-Pd NPs) represent a promising catalyst for organohalide remediation in water and sediments. However, the available information regarding their possible impact in case of release into the environment, particularly on the environmental microbiota, is limited. In this study the toxicity of bio-Pd NPs on the model marine bacterium V. fischeri was assessed. The impacts of different concentrations of bio-Pd NPs on the respiratory metabolisms (i.e. organohalide respiration, sulfate reduction and methanogenesis) and the structure of a PCB-dechlorinating microbial community enriched form a marine sediment were also investigated in microcosms mimicking the actual sampling site conditions. Bio-Pd NPs had no toxic effect on V. fischeri. In addition, they had no significant effects on PCB-dehalogenating activity, while showing a partial, dose-dependent inhibitory effect on sulfate reduction as well as on methanogenesis. No toxic effects by bio-Pd NPs could be also observed on the total bacterial community structure, as its biodiversity was increased compared to the not exposed community. In addition, resilience of the microbial community to bio-Pd NPs exposure was observed, being the final community organization (Gini coefficient) of samples exposed to bio-Pd NPs similar to that of the not exposed one. Considering all the factors evaluated, bio-Pd NPs could be deemed as non-toxic to the marine microbiota in the conditions tested. This is the first study in which the impact of bio-Pd NPs is extensively evaluated over a microbial community in relevant environmental conditions, providing important information for the assessment of their environmental safety.

  17. NPS Solar Cell Array Tester Cubesat Flight Testing and Integration

    DTIC Science & Technology

    2014-09-01

    AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE NPS SOLAR CELL ARRAY TESTER CUBESAT FLIGHT TESTING AND INTEGRATION 5. FUNDING NUMBERS 6...DISTRIBUTION CODE A 13. ABSTRACT (maximum 200 words) The Naval Postgraduate School Solar Cell Array Tester (NPS-SCAT) is the first CubeSat for the...Naval Postgraduate School (NPS). The NPS-SCAT mission was designed to measure solar cell performance degradation in low earth orbit . NPS-SCAT serves as

  18. Nanoparticle toxicity and cancer

    NASA Astrophysics Data System (ADS)

    Prevenslik, T.

    2011-07-01

    Nanoparticles (NPs) have provided significant advancements in cancer treatment. But as in any technology, there is a darkside. Experiments have shown NPs in body fluids pose a health risk by causing DNA damage that in of itself may lead to cancer. To avoid the dilemma that NPs are toxic to both cancer cells and DNA alike, the mechanism of NP toxicity must be understood so that the safe use of NPs may go forward. Reactive oxidative species (ROS) of peroxide and hydroxyl radicals damage the DNA by chemical reaction, but require NPs provide energies of about 5 eV not possible by surface effects. Only electromagnetic (EM) radiations beyond ultraviolet (UV) levels may explain the toxicity of NPs. Indeed, experiments show DNA damage from <100 nm NPs mimic the same reaction pathways of conventional sources of ionizing radiation, Hence, it is reasonable to hypothesize that NPs produce their own source of UV radiation, albeit at low intensity. Ionizing radiation from NPs at UV levels is consistent with the theory of QED induced EM radiation. QED stands for quantum electrodynamics. By this theory, fine < 100 nm NPs absorb low frequency thermal energy in the far infrared (FIR) from collisions with the water molecules in body fluids. Since quantum mechanics (QM) precludes NPs from having specific heat, absorbed EM collision energy cannot be conserved by an increase in temperature. But total internal reflection (TIR) momentarily confines the absorbed EM energy within the NP. Conservation proceeds by the creation of QED photons by frequency up-conversion of the absorbed EM energy to the TIR confinement frequency, typically beyond the UV. Subsequently, the QED photons upon scattering from atoms within the NP avoid TIR confinement and leak UV to the surroundings, thereby explaining the remarkable toxicity of NPs. But QED radiation need not be limited to natural or man-made NPs. Extensions suggest UV radiation is produced from biological NPs within the body, e.g., enzyme induced

  19. NPS-SCAT: Electrical Power System

    DTIC Science & Technology

    2009-09-01

    DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE NPS-SCAT; Electrical Power System 6. AUTHOR( S ) Lawrence Tyrone Dorn Jr. 5. FUNDING...NUMBERS 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) Naval Postgraduate School Monterey, CA 93943-5000 8. PERFORMING ORGANIZATION REPORT NUMBER...9. SPONSORING /MONITORING AGENCY NAME( S ) AND ADDRESS(ES) N/A 10. SPONSORING/MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES The

  20. NPS Gas Gun for Planar Impact Studies

    NASA Astrophysics Data System (ADS)

    Cheong Ho, Chien; Hixson, Robert

    2009-11-01

    The Naval Postgraduate School (NPS) commissioned a Gas Gun for shock wave studies on 9^th October 2009, by performing the first experiment. The Gas Gun is the key element of NPS Shock Wave Research Program within the Physics Department, where well-characterized planar impacts are essential for obtaining high quality data, to characterize a solid material. This first experiment was very successful, and returned key data on the quality of the impact conditions created. The Gas Gun is designed by SANDIA NATIONAL LABORATORIES, and the NPS spent twelve months fabricating the components of the Gas Gun and six months assembling the Gas Gun. Three inch projectile are launched at velocities up to 0.5 km/s, creating high pressure and temperature states that can be used to characterize the fundamental response of relevant materials to dynamic loading. The projectile is launched from a `wrap around' gas breech where helium gas is pressurized to relatively low pressure. This gas is used to accelerate the projectile down a 3m barrel. Upon impact, the speed of the projectile and the flatness of the impact is measured, via a stepped circular pin array circuit. The next stage of development for the Gas Gun is to integrate a Velocity Interferometer System for Any Reflector (VISAR). The VISAR sees all the waves that flow through the target plate as a result of the impact. This is a key diagnostic for determining material properties under dynamic loading conditions.

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

    SciTech Connect

    Zhou, Wenhui; Cao, Minhua Li, Na; Su, Shuangyue; Zhao, Xinyu; Wang, Jiangqiang; Li, Xianghua; Hu, Changwen

    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 new 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.

  2. Silver nanoparticle-initiated chemiluminescence reaction of luminol-AgNO3 and its analytical application.

    PubMed

    Liu, Cui; Li, Baoxin

    2011-07-01

    Ag(+) has been regarded as an inert chemiluminescent oxidant. In this work, it was found that in the presence of silver nanoparticles (AgNPs), AgNO(3) could react with luminol to produce strong chemiluminescence (CL). The AgNPs with smaller size could initiate stronger CL emission. To investigate the CL mechanism of the AgNPs-luminol-AgNO(3) system, the UV-visible spectra and the CL spectrum of the CL system were obtained. The CL reaction mechanism involving catalysis was proposed. Compared with the reported nanoparticles-luminol-H(2)O(2) CL system, the AgNPs-luminol-AgNO(3) CL system has the advantages of low background and good stability. Moreover, the new CL system was used in immunoassay for IgG.

  3. Solution structure of peptide AG4 used to form silver nanoparticles

    SciTech Connect

    Lee, Eunjung; Kim, Dae-Hee; Woo, Yoonkyung; Hur, Ho-Gil; Lim, Yoongho

    2008-11-21

    The preparation of silver nanoparticles (AgNPs) is of great interest due to their various biological activities, such as observed in their antimicrobial and wound healing actions. Moreover, the formation of AgNPs using silver-binding peptide has certain advantages because they can be made in aqueous solution at ambient temperature. The solution structure of the silver-binding peptide AG4 was determined using nuclear magnetic resonance spectroscopy, and the site of the AG4 interaction with AgNPs was elucidated.

  4. Green synthesis of ZnO NPs from various parts of Azhadirachta indica (neem) plant as biotemplates for anti-bacterial applications

    NASA Astrophysics Data System (ADS)

    Sharma, Savita; Oudhia, Anjali

    2016-05-01

    A green and cost effective method of production of ZnO nanoparticles (NPs) was developed using extracts from different parts of Neem plant (e.g. leaf, seed, and stem) as bio templates. ZnO NPs obtained through these bio-templates exhibit different structures, morphologies and optical properties, showing potential of the present method in preparing NPs with desired properties, FTIR and XRD techniques were used for characterization. A comparison of antibacterial activities of ZnO NPs show decreasing zone of inhibition with increasing particle sizes. The as prepared ZnO NPs functionalized with various materials to make them bio compatible. It was observed that natural tri-peptide GSH was most effective capping agents for controlling the toxicity of ZnO NPs. A mechanism is proposed to explain the variation in growth patterns and properties of ZnO NPs obtained from the aforementioned bio-templates.

  5. Individual and Co Transport Study of Titanium Dioxide NPs and Zinc Oxide NPs in Porous Media

    PubMed Central

    Kumari, Jyoti; Mathur, Ankita; Rajeshwari, A.; Venkatesan, Arthi; S, Satyavati; Pulimi, Mrudula; Chandrasekaran, Natarajan; Nagarajan, R.; Mukherjee, Amitava

    2015-01-01

    The impact of pH and ionic strength on the mobility (individual and co-transport) and deposition kinetics of TiO2 and ZnO NPs in porous media was systematically investigated in this study. Packed column experiments were performed over a series of environmentally relevant ionic strengths with both NaCl (0.1−10 mM) and CaCl2 (0.01–0.1mM) solutions and at pH 5, 7, and 9. The transport of TiO2 NPs at pH 5 was not significantly affected by ZnO NPs in solution. At pH 7, a decrease in TiO2 NP transport was noted with co-existence of ZnO NPs, while at pH 9 an increase in the transport was observed. At pH 5 and 7, the transport of ZnO NPs was decreased when TiO2 NPs was present in the solution, and at pH 9, an increase was noted. The breakthrough curves (BTC) were noted to be sensitive to the solution chemistries; the decrease in the breakthrough plateau with increasing ionic strength was observed under all examined pH (5, 7, and 9). The retention profiles were the inverse of the plateaus of BTCs, as expected from mass balance considerations. Overall, the results from this study suggest that solution chemistries (ionic strength and pH) are likely the key factors that govern the individual and co-transport behavior of TiO2 and ZnO NPs in sand. PMID:26252479

  6. Green synthesis of halloysite nanotubes supported Ag nanoparticles for photocatalytic decomposition of methylene blue

    NASA Astrophysics Data System (ADS)

    Zou, MeiLing; Du, MingLiang; Zhu, Han; Xu, CongSheng; Fu, YaQin

    2012-08-01

    Using tea polyphenols (TPs) as a reductant, Ag nanoparticles (AgNPs) supported on halloysite nanotubes (HNTs) were simply and greenly synthesized for the photocatalytic decomposition of methylene blue (MB). HNTs were initially functionalized by N-β-aminoethyl-γ-aminopropyl trimethoxysilane (AEAPTMS) to introduce amino groups to form N-HNTs to fasten the AgNPs; then AgNPs were synthesized and ‘anchored’ on the surface of the HNTs. Fourier transform infrared spectroscopy was employed to testify the amino groups on the surface of the HNTs. Transmission electron microscopy, field-emission scanning electron microscopy and x-ray diffraction were utilized to characterize the structure and morphology of the synthesized HNTs supported by the AgNPs (AgNPs@N-HNTs). The results showed that the AgNPs had been synthesized and ‘anchored’ onto the surface of the HNTs with a diameter of about 20-30 nm. X-ray photoelectron spectroscopy analysis revealed the chelating interaction between the AgNPs and N atoms together with the TP molecular. The photocatalytic activity of the as-prepared AgNPs@N-HNTs catalyst was evaluated by decomposition of MB; the results showed that the prepared catalyst exhibited excellent catalytic activity and high adsorption capability to MB.

  7. The role of Ag nanoparticles in inverted polymer solar cells: Surface plasmon resonance and backscattering centers

    NASA Astrophysics Data System (ADS)

    Xu, Peng; Shen, Liang; Meng, Fanxu; Zhang, Jiaqi; Xie, Wenfa; Yu, Wenjuan; Guo, Wenbin; Jia, Xu; Ruan, Shengping

    2013-03-01

    Here, we demonstrate silver (Ag) nanoparticles (NPs) existing in molybdenum trioxide (MoO3) buffer layers can improve the photocurrent by surface plasmon resonance (SPR) and backscattering enhancement. The device structure is glass/indium tin oxides/titanium dioxide (TiO2)/regioregular poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester/MoO3/Ag NPs/MoO3/Ag. Compared to the device without Ag NPs, the short current density (Jsc) is improved from 7.76 ± 0.14 mA/cm2 to 8.89 ± 0.12 mA/cm2, and the power conversion efficiency is also enhanced from 2.70% ± 0.11% to 3.35% ± 0.08%. The transmittance spectra show that the device with Ag NPs has weaker transmittance than the device without, which could be attributed to the photons absorption of Ag NPs and light scattering by Ag NPs. The absorption profile of the devices with or without Ag NPs is simulated using finite-difference time-domain methods. It is approved that the Ag NPs result in the absorption improvement by SPR and backscattering enhancement.

  8. Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

    NASA Astrophysics Data System (ADS)

    Nguyen, Thi Kim Lan; Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Hien Nguyen, Quoc

    2013-12-01

    Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag+ dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag+ is occurred by hydrated electron (e-aq) and hydrogen atom (H•) generated during radiolysis of ethanol/water. The conversion doses (Ag+ → Ag0) were determined by UV-Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5-40 nm for Ag+ concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg-1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc.

  9. High Visible Photoelectrochemical Activity of Ag Nanoparticle-Sandwiched CdS/Ag/ZnO Nanorods.

    PubMed

    Yang, Xu; Li, Hui; Zhang, Wu; Sun, Mingxuan; Li, Lequn; Xu, Ning; Wu, Jiada; Sun, Jian

    2017-01-11

    We report on the sensitizing of CdS-coated ZnO (CdS/ZnO) nanorods (NRs) by Ag nanoparticles (NPs) embedded between the CdS coating and the ZnO nanorod and the improved optical and photoelectrochemical properties of the Ag NP-sandwiched nanostructure CdS/Ag/ZnO NRs. The CdS/Ag/ZnO NRs were fabricated by growing Ag NPs on hydrothermally grown ZnO NRs and subsequently depositing CdS coatings followed by subsequent N2 annealing. The structure of the fabricated CdS/Ag/ZnO NRs was characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman backscattering, revealing that the ZnO NRs and the CdS coatings are both structured with hexagonal wurtzite and the Ag NPs contact well with ZnO and CdS. Optical properties were evaluated by measuring optical absorption and photoluminescence, showing that the Ag NPs behave well as sensitizers for optical property improvement and the CdS/Ag/ZnO NRs exhibit better photoresponse in a wide spectral region than CdS/ZnO because of plasmon-enhanced absorption due to the embedment of Ag NPs. The Ag NPs also serve as electron relays from CdS to ZnO, facilitating electron transfer from the CdS coatings to the ZnO NRs. The excellent photoresponse and efficient electron transfer make the CdS/Ag/ZnO NRs highly photoelectrochemically active. The CdS/Ag/ZnO NRs fabricated on indium-tin oxide present much better photoelectrochemical performance as photoanodes working in the visible region than CdS/ZnO NRs without Ag NPs. Under visible illumination, a maximum optical-to-chemical conversion efficiency of 3.13% is obtained for CdS/Ag/ZnO NR photoanodes against 1.35% for CdS/ZnO NR photoanodes.

  10. Ag/Pd core-shell nanoparticles by a successive method: Pulsed laser ablation of Ag in water and reduction reaction of PdCl2

    NASA Astrophysics Data System (ADS)

    Mottaghi, N.; Ranjbar, M.; Farrokhpour, H.; Khoshouei, M.; Khoshouei, A.; Kameli, P.; Salamati, H.; Tabrizchi, M.; Jalilian-Nosrati, M.

    2014-02-01

    In this study Ag/Pd nanoparticles (NPs) have been fabricated by a successive method; first, colloids of Ag nanoparticles (NPs) have been prepared in water by pulsed laser ablation in liquid (PLAL) method. Then PdCl2 solution (up to 0.2 g/l) were added to the as-prepared or aged colloidal Ag NPs. Characterizations were done using UV-vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmissions electron microscopy (TEM) techniques. Spectroscopy data showed that surface plasmon resonance (SPR) peaks of as-prepared Ag NPs at about λ = 400 nm were completely extinguished after addition of PdCl2 solution while this effect was not observed when aged Ag NPs are used. XRD and XPS results revealed that by addition of the PdCl2 solution into the as-prepared Ag NPs, metallic palladium, and silver chloride composition products are generated. TEM images revealed that as a result of this reaction, single and core-shell nanoparticles are obtained and their average sizes are 2.4 nm (Ag) and 3.2 nm (Ag/Pd). The calculated d-spacing values form XRD data with observations on high magnification TEM images were able to explain the chemical nature of different parts of Ag/Pd NPs.

  11. Microfluidic synthesis of Ag@Cu2O core-shell nanoparticles with enhanced photocatalytic activity.

    PubMed

    Tao, Sha; Yang, Mei; Chen, Huihui; Ren, Mingyue; Chen, Guangwen

    2017-01-15

    A microfluidic-based method for the continuous synthesis of Ag@Cu2O core-shell nanoparticles (NPs) has been developed. It only took 32s to obtain Ag@Cu2O core-shell NPs, indicating a high efficiency of this microfluidic-based method. Triangular Ag nanoprisms were employed as the cores for the overgrowth of Cu2O through the reduction of Cu(OH)4(2-) with ascorbic acid. The as-synthesized samples were characterized by XRD, TEM, SEM, HAADF-STEM, EDX, HRTEM, UV-vis spectra and N2 adsorption-desorption. The characterization results revealed that the as-synthesized Ag@Cu2O core-shell NPs exhibited a well-defined core-shell nanostructure with a polycrystalline shell, which was composed of numbers of Cu2O domains epitaxially growing on the triangular Ag nanoprism. It was concluded that the synthesis parameters such as the molar ratio of trisodium citrate to AgNO3, H2O2 to AgNO3, NaOH to CuSO4, ascorbic acid to CuSO4 and AgNO3 to CuSO4 had significant effect on the synthesis of Ag@Cu2O core-shell NPs. Moreover, Ag@Cu2O core-shell NPs exhibited superior catalytic activity in comparison with pristine Cu2O NPs towards the visible light-driven degradation of methyl orange. This enhanced photocatalytic activity of Ag@Cu2O core-shell NPs was attributed to the larger BET surface area and improved charge separation efficiency. The trapping experiment indicated that holes and superoxide anion radicals were the major reactive species in the photodegradation of methyl orange over Ag@Cu2O core-shell NPs. In addition, Ag@Cu2O core-shell NPs showed no obvious deactivation in the cyclic test.

  12. SERS detection and antibacterial activity from uniform incorporation of Ag nanoparticles with aligned Si nanowires

    NASA Astrophysics Data System (ADS)

    Chen, Chia-Yun; Hsu, Li-Jen; Hsiao, Po-Hsuan; Yu, Chang-Tze Ricky

    2015-11-01

    We present a facile, reliable and controllable two-steps electroless deposition for uniformly decorating the silver (Ag) nanoparticles (NPs) on the highly aspect ratio of silicon (Si) nanowire arrays. Different from the direct Ag-loading process, which is normally challenged by the non-uniform coating of Ag, the formation of Ag NPs using such innovative electroless process is no longer to be limited at top nanowire surfaces solely; instead, each Ag+/Si interface can initiate the galvanic reduction of Ag+ ions, thus resulting in the uniform formation of Ag NPs on the entire Si nanowire arrays. In addition, systematic explorations of surface-enhanced Raman scattering (SERS) capability as well as antibacterial activity of the Ag/Si-incorporated nanostructures were performed, and the optimized Ag loadings on Si nanowire-based substrates along with the kinetic investigations were further revealed, which may benefit their practical applications in sensing, medical and biological needs.

  13. Study of antibacterial activity of Ag and Ag2CO3 nanoparticles stabilized over montmorillonite

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Pourahmad, A.; Mehdipour Moghaddam, M. J.; Sadeghi, A.

    2015-02-01

    Silver carbonate and silver nanoparticles (NPs) over of stabilizer montmorillonite (MMT) have been synthesized in aqueous and polyol solvent, respectively. Dispersions of silver nanoparticles have been prepared by the reduction of silver nitrate over of MMT in presence and absence of Na2CO3 compound in ethylene glycol. It was observed that montmorillonite was capable of stabilizing formed Ag nanoparticles through the reduction of Ag+ ions in ethylene glycol. Na2CO3 was used as carbonate source in synthesis of Ag2CO3 NPs in water solvent and also for controlling of Ag nanoparticles size in ethylene glycol medium. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (DRS). The TEM images showed that Ag NPs size in presence Na2CO3 salts was smaller than without that. The results indicated intercalation of Ag and Ag2CO3 nanoparticles into the montmorillonite clay layers. The diffuse reflectance spectra exhibited a strong surface plasmon resonance (SPR) adsorption peak in the visible region, resulting from Ag nanoparticles. The antibacterial testing results showed that the Ag2CO3-MMT nanocomposite exhibited an antibacterial activity higher than Ag-MMT sample against Escherichia coli.

  14. Peptide-biphenyl hybrid-capped AuNPs: stability and biocompatibility under cell culture conditions

    NASA Astrophysics Data System (ADS)

    Connolly, Mona; Pérez, Yolanda; Mann, Enrique; Herradón, Bernardo; Fernández-Cruz, María L.; Navas, José M.

    2013-07-01

    In this study, we explored the biocompatibility of Au nanoparticles (NPs) capped with peptide-biphenyl hybrid (PBH) ligands containing glycine (Gly), cysteine (Cys), tyrosine (Tyr), tryptophan (Trp) and methionine (Met) amino acids in the human hepatocellular carcinoma cell line Hep G2. Five AuNPs, Au[(Gly-Tyr-Met)2B], Au[(Gly-Trp-Met)2B], Au[(Met)2B], Au[(Gly-Tyr-TrCys)2B] and Au[(TrCys)2B], were synthesised. Physico-chemical and cytotoxic properties were thoroughly studied. Transmission electron micrographs showed isolated near-spherical nanoparticles with diameters of 1.5, 1.6, 2.3, 1.8 and 2.3 nm, respectively. Dynamic light scattering evidenced the high stability of suspensions in Milli-Q water and culture medium, particularly when supplemented with serum, showing in all cases a tendency to form agglomerates with diameters approximately 200 nm. In the cytotoxicity studies, interference caused by AuNPs with some typical cytotoxicity assays was demonstrated; thus, only data obtained from the resazurin based assay were used. After 48-h incubation, only concentrations ≥50 μg/ml exhibited cytotoxicity. Such doses were also responsible for an increase in reactive oxygen species (ROS). Some differences were observed among the studied NPs. Of particular importance is the AuNPs capped with the PBH ligand (Gly-Tyr-TrCys)2B showing remarkable stability in culture medium, even in the absence of serum. Moreover, these AuNPs have unique biological effects on Hep G2 cells while showing low toxicity. The production of ROS along with supporting optical microscopy images suggests cellular interaction/uptake of these particular AuNPs. Future research efforts should further test this hypothesis, as such interaction/uptake is highly relevant in drug delivery systems.

  15. Peptide-biphenyl hybrid-capped AuNPs: stability and biocompatibility under cell culture conditions.

    PubMed

    Connolly, Mona; Pérez, Yolanda; Mann, Enrique; Herradón, Bernardo; Fernández-Cruz, María L; Navas, José M

    2013-07-06

    In this study, we explored the biocompatibility of Au nanoparticles (NPs) capped with peptide-biphenyl hybrid (PBH) ligands containing glycine (Gly), cysteine (Cys), tyrosine (Tyr), tryptophan (Trp) and methionine (Met) amino acids in the human hepatocellular carcinoma cell line Hep G2. Five AuNPs, Au[(Gly-Tyr-Met)2B], Au[(Gly-Trp-Met)2B], Au[(Met)2B], Au[(Gly-Tyr-TrCys)2B] and Au[(TrCys)2B], were synthesised. Physico-chemical and cytotoxic properties were thoroughly studied. Transmission electron micrographs showed isolated near-spherical nanoparticles with diameters of 1.5, 1.6, 2.3, 1.8 and 2.3 nm, respectively. Dynamic light scattering evidenced the high stability of suspensions in Milli-Q water and culture medium, particularly when supplemented with serum, showing in all cases a tendency to form agglomerates with diameters approximately 200 nm. In the cytotoxicity studies, interference caused by AuNPs with some typical cytotoxicity assays was demonstrated; thus, only data obtained from the resazurin based assay were used. After 48-h incubation, only concentrations ≥50 μg/ml exhibited cytotoxicity. Such doses were also responsible for an increase in reactive oxygen species (ROS). Some differences were observed among the studied NPs. Of particular importance is the AuNPs capped with the PBH ligand (Gly-Tyr-TrCys)2B showing remarkable stability in culture medium, even in the absence of serum. Moreover, these AuNPs have unique biological effects on Hep G2 cells while showing low toxicity. The production of ROS along with supporting optical microscopy images suggests cellular interaction/uptake of these particular AuNPs. Future research efforts should further test this hypothesis, as such interaction/uptake is highly relevant in drug delivery systems.

  16. Peptide-biphenyl hybrid-capped AuNPs: stability and biocompatibility under cell culture conditions

    PubMed Central

    2013-01-01

    In this study, we explored the biocompatibility of Au nanoparticles (NPs) capped with peptide-biphenyl hybrid (PBH) ligands containing glycine (Gly), cysteine (Cys), tyrosine (Tyr), tryptophan (Trp) and methionine (Met) amino acids in the human hepatocellular carcinoma cell line Hep G2. Five AuNPs, Au[(Gly-Tyr-Met)2B], Au[(Gly-Trp-Met)2B], Au[(Met)2B], Au[(Gly-Tyr-TrCys)2B] and Au[(TrCys)2B], were synthesised. Physico-chemical and cytotoxic properties were thoroughly studied. Transmission electron micrographs showed isolated near-spherical nanoparticles with diameters of 1.5, 1.6, 2.3, 1.8 and 2.3 nm, respectively. Dynamic light scattering evidenced the high stability of suspensions in Milli-Q water and culture medium, particularly when supplemented with serum, showing in all cases a tendency to form agglomerates with diameters approximately 200 nm. In the cytotoxicity studies, interference caused by AuNPs with some typical cytotoxicity assays was demonstrated; thus, only data obtained from the resazurin based assay were used. After 48-h incubation, only concentrations ≥50 μg/ml exhibited cytotoxicity. Such doses were also responsible for an increase in reactive oxygen species (ROS). Some differences were observed among the studied NPs. Of particular importance is the AuNPs capped with the PBH ligand (Gly-Tyr-TrCys)2B showing remarkable stability in culture medium, even in the absence of serum. Moreover, these AuNPs have unique biological effects on Hep G2 cells while showing low toxicity. The production of ROS along with supporting optical microscopy images suggests cellular interaction/uptake of these particular AuNPs. Future research efforts should further test this hypothesis, as such interaction/uptake is highly relevant in drug delivery systems. PMID:23829784

  17. Inhibition of gold nanoparticles (AuNPs) on pathogenic biofilm formation and invasion to host cells

    PubMed Central

    Yu, Qilin; Li, Jianrong; Zhang, Yueqi; Wang, Yufan; Liu, Lu; Li, Mingchun

    2016-01-01

    Owing to the growing infectious diseases caused by eukaryotic and prokaryotic pathogens, it is urgent to develop novel antimicrobial agents against clinical pathogenic infections. Biofilm formation and invasion into the host cells are vital processes during pathogenic colonization and infection. In this study, we tested the inhibitory effect of Au nanoparticles (AuNPs) on pathogenic growth, biofilm formation and invasion. Interestingly, although the synthesized AuNPs had no significant toxicity to the tested pathogens, Candida albicans and Pseudomonas aeruginosa, the nanoparticles strongly inhibited pathogenic biofilm formation and invasion to dental pulp stem cells (DPSCs). Further investigations revealed that AuNPs abundantly bound to the pathogen cells, which likely contributed to their inhibitory effect on biofilm formation and invasion. Moreover, treatment of AuNPs led to activation of immune response-related genes in DPSCs, which may enhance the activity of host immune system against the pathogens. Zeta potential analysis and polyethylene glycol (PEG)/polyethyleneimine (PEI) coating tests further showed that the interaction between pathogen cells and AuNPs is associated with electrostatic attractions. Our findings shed novel light on the application of nanomaterials in fighting against clinical pathogens, and imply that the traditional growth inhibition test is not the only way to evaluate the drug effect during the screening of antimicrobial agents. PMID:27220400

  18. Antioxidant enzyme activities as biomarkers of fluvial biofilm to ZnO NPs ecotoxicity and the Integrated Biomarker Responses (IBR) assessment.

    PubMed

    Hou, Jun; You, Guoxiang; Xu, Yi; Wang, Chao; Wang, Peifang; Miao, Lingzhan; Dai, Shanshan; Lv, Bowen; Yang, Yangyang

    2016-11-01

    The presence of ZnO nanoparticles (ZnO NPs) in natural waters has raised concerns about their environmental impacts, but the potential influences of ZnO NPs on fluvial biofilm have not been reported. In this study, the utility of antioxidant enzyme activities (AEA) as biomarkers of fluvial biofilm to ZnO NPs toxicity and a method that combines AEA into an index of "Integrated Biomarker Responses (IBR)" were studied. Compared with the absence of ZnO NPs, scanning electron microscopy (SEM) images revealed that a large amount of ZnO NPs were adsorbed onto biofilm and these NPs exerted adverse effects on the viability of bacteria in biofilm. The production of reactive oxygen species (ROS) with high concentrations (30 and 100mg/L) of ZnO NPs exposure reached to 184% and 244% of the control, while no cell leakage and membrane damage were observed. After exposure to ZnO NPs for 0.25 and 3 days, the activities of catalase (CAT), superoxide dismutase (SOD) and glutathione reductase (GR), glutathione peroxidase (GSH-Px) were significantly increased, respectively. At the end of exposure period (21 days), the AEA with the presence of 1mg/L ZnO NPs exposure were comparable to the control, while most of those in high concentrations of ZnO NPs were decreased. The results of IBR showed that the biofilm can adapt to 1mg/L ZnO NPs exposure, while be seriously damaged by 30 and 100mg/L ZnO NPs after 3 and 0.25 days. IBR can be used as an appropriate evaluation system of the toxicity effects of ZnO NPs on fluvial biofim.

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

    PubMed Central

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

    2017-01-01

    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. PMID:28322256

  20. 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.

  1. Long-term transformation and fate of manufactured ag nanoparticles in a simulated large scale freshwater emergent wetland.

    PubMed

    Lowry, Gregory V; Espinasse, Benjamin P; Badireddy, Appala Raju; Richardson, Curtis J; Reinsch, Brian C; Bryant, Lee D; Bone, Audrey J; Deonarine, Amrika; Chae, Soryong; Therezien, Mathieu; Colman, Benjamin P; Hsu-Kim, Heileen; Bernhardt, Emily S; Matson, Cole W; Wiesner, Mark R

    2012-07-03

    Transformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag(2)S (~52%), whereas AgNPs in the subaquatic sediment were present as Ag(2)S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (~3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5-3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L).

  2. Physical assessment of toxicology at nanoscale: nano dose-metrics and toxicity factor

    NASA Astrophysics Data System (ADS)

    Pompa, P. P.; Vecchio, G.; Galeone, A.; Brunetti, V.; Maiorano, G.; Sabella, S.; Cingolani, R.

    2011-07-01

    In this work, we propose a systematic and reproducible evaluation of nanoparticles (NPs) toxicology in living systems, based on a physical assessment and quantification of the toxic effects of NPs by the experimental determination of the key parameter affecting the toxicity outcome (i.e., the number of NPs) and of the NPs ``toxicity factor''. Such a strategy was applied to a well determined scenario, i.e., the ingestion of citrate-capped gold NPs (AuNPs) of different sizes by the model system Drosophila melanogaster. Using these AuNPs as a reference toxicity standard, we were able to define different regions in the multiparametric space of toxicity, enabling the classification of the toxic levels of other nanomaterials, such as quantum dots and pegylated AuNPs. This approach may pave the way to a systematic classification of nanomaterials, leading to important developments in risk assessment and regulatory approval, as well as in a wide range of nanomedicine applications.

  3. 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.

  4. Low temperature sintering of Ag nanoparticles for flexible electronics packaging

    NASA Astrophysics Data System (ADS)

    Hu, A.; Guo, J. Y.; Alarifi, H.; Patane, G.; Zhou, Y.; Compagnini, G.; Xu, C. X.

    2010-10-01

    We achieve robust bonding of Cu wires to Cu pads on polyimide with silver nanopaste cured at 373 K. The paste is prepared by simply condensing Ag nanoparticle (NP) solution via centrifuging. The bonding is formed by solid state sintering of Ag NPs through neck growth and direct metallic bonding between clean Ag-Cu interfaces. Both experiment and Monte Carlo simulation confirm that the melting point of joint clusters increases during sintering. This creates improved bonds for use at an elevated operating temperature using Ag NPs.

  5. Toxicity of combined mixtures of nanoparticles to plants.

    PubMed

    Jośko, Izabela; Oleszczuk, Patryk; Skwarek, Ewa

    2017-06-05

    An increasing production and using of nanoproducts results in releasing and dispersing nanoparticles (NPs) in the environment. Being released into various environment components, NPs may interact with numerous pollutants, including other NPs. This research aimed at assessing toxicity of combined binary mixtures of NPs. The study focused on assessing mixtures of NPs believed to be toxic (nano-ZnO+nano-CuO) and nano-ZnO/nano-CuO with the ones that are insignificantly toxic or non-toxic NPs (nano-TiO2/nano-Cr2O3/nano-Fe2O3). Toxicity of combined mixtures proved comparable to toxicity of individual mixtures of NPs (the sum of effects triggered by individual types of NPs comprising respective mixtures). Toxicity evaluation was based on two parameters: seed germination and inhibition of root growth with respect to four plant species: Lepidium sativum, Linum utisassimmum, Cucumis sativus and Triticum aestivum. The findings showed combined mixtures of NPs to be significantly less toxic in comparison to individual mixtures, irrespective of their components. Within the scope of concentrations used, greatest differences between the toxicity of mixtures were reported at the 100mgL(-1) concentration. Toxicity levels of combined and individual mixtures might have been determined by a lower total concentration of Zn and Cu metals and a greater aggregation of particles in combined mixtures than in individual mixtures.

  6. An Au/AgBr-Ag heterostructure plasmonic photocatalyst with enhanced catalytic activity under visible light.

    PubMed

    Purbia, Rahul; Paria, Santanu

    2017-01-17

    This study reports an easy synthesis protocol of a novel bimetallic silver halide (Au/AgBr-Ag) plasmonic heterostructure as a visible light induced photocatalyst. In this process, first CTAB capped Au NPs were coated with AgBr, and then Ag nanoparticles were formed on the surface of AgBr by photoreduction, while exposing to daylight at room temperature. The presence of Au and Ag improves the visible absorption ability of NPs and avoids charge recombination of the semiconductor AgBr during photoexcitation, which in turn enhances 16 and 8.9 fold the photocatalytic efficiency of Rhodamine B dye degradation under visible light irradiation compared to that of pure AgBr and AgBr/Ag, respectively. The recycling tests of the photocatalyst show only ∼8.7% decrease in efficiency after the 5(th) cycle of reuse without changing the morphology. During the photocatalytic process, active superoxide radicals (O2˙(-)) play a major role, proved through scavenger trapping and photoluminescence experiments. The presence of two plasmonic metals (Au and Ag) in the heterostructure helps to improve visible light absorption as well as avoid charge recombination of the semiconductor AgBr to act as a better photocatalyst. Since this heteronanostructure can be easily synthesized by a one-step method, this study could provide a new approach for the development of efficient bimetallic/semiconductor halide plasmonic photocatalysts with enhanced visible absorption and better charge separation.

  7. Biosynthesis of quasi-spherical Ag nanoparticle by Pseudomonas aeruginosa as a bioreducing agent

    NASA Astrophysics Data System (ADS)

    Taheri Otaqsara, S. M.

    2011-12-01

    Use of microorganism as a novel and eco-friendly strategy to production of nanomaterials is an important aspect of modern nanotechnology. Biosynthesis of quasi-spherical silver nanoparticles (Ag-NPs) has been investigated using Pseudomonas aeruginosa. We observe that silver (Ag+) ions when exposed to P. aeruginosa biomass are reduced in solution, thereby leading to the formation of Ag-NPs. Quasi-spherical shape and nearly well distribution and FCC crystal structure of Ag-NPs were confirmed by XRD pattern, STM and TEM micrographs. UV-Vis spectra show a surface plasmon resonance (SPR) band at ~ 435 nm.

  8. Simple and Rapid Quantitative Determination of Thiol-Containing Toxicants Using Silver Nanoparticles as an Affinity Probe

    NASA Astrophysics Data System (ADS)

    Sharma, A.; Tapadia, K.

    2017-01-01

    A rapid and low-cost nano-drop spectrophotometric method using citrate-modified silver nanoparticles (Ag NPs) for the determination of thiol-containing toxicants was developed. The introduction of thioglycolic acid (TGA) and thiourea (TU) reduced the overall surface charge of Ag NPs, resulting in aggregation of Ag NPs, and a colorimetric response that was individually correlated with the concentration of TGA and TU. Under optimum experimental conditions, the maximum molar absorptivity values for TGA and TU were 1.04 × 105 and 2.13 × 105 L × mol-1 × cm-1, respectively, at λmax of 415 nm. The linear range used was 0.5-2.5 mg/L for TGA, and 0.3-1.5 mg/L for TU. The detection limits (3S) and % relative standard deviation (RSD) for the method were found to be 3 ppb, 2 ppb, and ±1.13%, ±0.96% for TGA and TU, respectively. This new chromogenic method provided a facile and sensitive scheme for the determination of TGA and TU, and could be applied for the determination of thiol-containing biomolecules. This scheme was tested for the analysis of real samples such as urine, blood, and environmental samples.

  9. Highly sensitive surface-enhanced Raman scattering detection of hexavalent chromium based on hollow sea urchin-like TiO2@Ag nanoparticle substrate.

    PubMed

    Zhou, Wen; Yin, Bin-Cheng; Ye, Bang-Ce

    2017-01-15

    As one of the most toxic heavy metals, hexavalent chromium (Cr(VI)) has long been a concern due to its threats to human health and the environment. In this work, we develop a sensitive surface-enhanced Raman scattering (SERS) sensor for highly specific detection of Cr(VI) using hollow sea urchin-like TiO2@Ag nanoparticles (NPs). The TiO2@Ag NPs are functionalized with glutathione (GSH) and used as substrates with 2-mercaptopyridine (2-MPy) as a Raman reporter for a recyclable SERS-active sensor, enabling ultrasensitive detection of Cr(VI). Excellent SERS signals of 2-MPy reporters are detected when GSH complexation with Cr(VI) causes aggregation of the TiO2@Ag NPs. The developed sensor exhibits good linearity in the range from 10nM to 2μM for Cr(VI) with a detection limit of ca. 1.45nM. It features excellent selectivity to Cr(VI) over other interfering metal ions, and good application for quantitative analysis of Cr(VI) in water samples. Moreover, the proposed SERS sensor can be fully regenerated when exposed to UV light as a result of the self-cleaning ability of the substrates. In contrast to the traditional SERS detection, the present work shed new light on the design and synthesis of hierarchically self-assembled 3D substrate for SERS, catalysis and biosensor development.

  10. New insight into daylight photocatalysis of AgBr@Ag: synergistic effect between semiconductor photocatalysis and plasmonic photocatalysis.

    PubMed

    Jiang, Jing; Li, Hao; Zhang, Lizhi

    2012-05-14

    Noble metal nanoparticles (NPs) are often used as electron scavengers in conventional semiconductor photocatalysis to suppress electron-hole (e(-)-h(+) ) recombination and promote interfacial charge transfer, and thus enhance photocatalytic activity of semiconductors. In this contribution, it is demonstrated that noble metal NPs such as Ag NPs function as visible-light harvesting and electron-generating centers during the daylight photocatalysis of AgBr@Ag. Novel Ag plasmonic photocatalysis could cooperate with the conventional AgBr semiconductor photocatalysis to enhance the overall daylight activity of AgBr@Ag greatly because of an interesting synergistic effect. After a systematic investigation of the daylight photocatalysis mechanism of AgBr@Ag, the synergistic effect was attributed to surface plasmon resonance induced local electric field enhancement on Ag, which can accelerate the generation of e(-)-h(+) pairs in AgBr, so that more electrons are produced in the conduction band of AgBr under daylight irradiation. This study provides new insight into the photocatalytic mechanism of noble metal/semiconductor systems as well as the design and fabrication of novel plasmonic photocatalysts.

  11. Non-covalent functionalization of graphene oxide by polyindole and subsequent incorporation of Ag nanoparticles for electrochemical applications

    NASA Astrophysics Data System (ADS)

    Dubey, Prashant; Kumar, Ashish; Prakash, Rajiv

    2015-11-01

    Reduced graphene oxide (r-GO) sheets have been modified by polyindole (PIn) via in situ chemical oxidation method to obtain stable dispersion in water and furthermore incorporation of Ag nanoparticles (Ag NPs); the resulting Ag NPs/PIn-r-GO nanocomposite is demonstrated for electrochemical applications. Ag NPs/r-GO and PIn/GO nanocomposites have also been prepared for its comparative study with Ag NPs/PIn-r-GO. Non-covalent functionalization of GO by PIn polymer leads to PIn-GO dispersion, which is stable for several months without any precipitation. This dispersed solution is used for formation of Ag NPs/PIn-r-GO nanocomposite. Various experimental tools like UV-vis, FTIR and TEM have been used to characterize as-synthesized materials. Thereafter electrochemical performance of as-synthesized nanocomposites have been compared for their charge capacitive behaviour (without its poisoning compared to Ag NPs/r-GO) which leads to be an excellent candidate for the possible applications such as electrocatalysis, charge storage devices, etc. We observed that Ag NPs/PIn-r-GO nanocomposite exhibits better processability and electroactivity as electrode material in comparison to Ag NPs/r-GO and PIn/GO nanocomposites due to synergistic effect of individual components.

  12. Influence of size, shape and core-shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiO x.

    PubMed

    D'Addato, Sergio; Pinotti, Daniele; Spadaro, Maria Chiara; Paolicelli, Guido; Grillo, Vincenzo; Valeri, Sergio; Pasquali, Luca; Bergamini, Luca; Corni, Stefano

    2015-01-01

    Ag and Ag@MgO core-shell nanoparticles (NPs) with a diameter of d = 3-10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiO x (Si/SiO x ). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served to preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation.

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

    PubMed

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

    2017-12-01

    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.

  14. 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.

  15. Green synthesis of Ag nanoparticles using Tamarind fruit extract for the antibacterial studies.

    PubMed

    Jayaprakash, N; Vijaya, J Judith; Kaviyarasu, K; Kombaiah, K; Kennedy, L John; Ramalingam, R Jothi; Munusamy, Murugan A; Al-Lohedan, Hamad A

    2017-04-01

    In the present study, first time we report the microwave-assisted green synthesis of silver nanoparticles (AgNPs) using Tamarindus indica natural fruit extract. The plant extract plays a dual role of reducing and capping agent for the synthesis of AgNPs. The formation of spherical shape AgNPs is confirmed by XRD, HR-SEM, and HR-TEM. The presence of face-centered cubic (FCC) silver is confirmed by XRD studies and the average crystallite size of AgNPs is calculated to be around 6-8nm. The average particle diameter is found to be around 10nm, which is identified from HR-TEM images. The purity of AgNPs is confirmed by EDX analysis. The presence of sigmoid curve in UV-Visible absorption spectra suggests that the reaction has complicated kinetic features. To investigate the functional groups of the extract and their involvement in the reduction of AgNO3 to form AgNPs, FT-IR studies are carried out. The redox peaks are observed in cyclic voltammetry in the potential range of -1.2 to +1.2V, due to the redox active components of the T. indica fruit extract. In photoluminescence spectroscopy, the excited and emission peaks were obtained at 432nm and 487nm, respectively. The as-prepared AgNPs showed good results towards antibacterial activities. Hence, the present approach is a facile, cost- effective, reproducible, eco-friendly, and green method.

  16. Novel Psychoactive Substances (NPS): a Study on Persian Language Websites

    PubMed Central

    BIGDELI, Imanollah; CORAZZA, Ornella; ASLANPOUR, Zoe; SCHIFANO, Fabrizio

    2013-01-01

    Background During the past few years, there has been an increasing recognition that Internet is playing a significant role in the synthesis, the distribution and the consumption of Novel Psychoactive Substances (NPS).The aim of this study was to assess the online availability of NPS in Persian language websites. Methods: The Google search engine was used to carry out an accurate qualitative assessment of information available on NPS in a sample of 104 websites. Results: The monitoring has led to the identification of 14 NPS including herbal, synthetic, pharmaceutical and combination drugs that have been sold online. Conclusion: The availability of online marketing of NPS in Persian language websites may constitute a public health challenge at least across three Farsi-speaking countries in the Middle East. Hence, descriptions of this phenomenon are valuable to clinicians and health professional in this region. Further international collaborative efforts may be able to tackle the growth and expansion of regular offer of NPS. PMID:23802109

  17. 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...

  18. Nanoparticle-induced pulmonary toxicity.

    PubMed

    Li, Jasmine Jia'en; Muralikrishnan, Sindu; Ng, Cheng-Teng; Yung, Lin-Yue Lanry; Bay, Boon-Huat

    2010-09-01

    In recent decades, advances in nanotechnology engineering have given rise to the rapid development of many novel applications in the biomedical field. However, studies into the health and safety of these nanomaterials are still lacking. The main concerns are the adverse effects to health caused by acute or chronic exposure to nanoparticles (NPs), especially in the workplace environment. The lung is one of the main routes of entry for NPs into the body and, hence, a likely site for accumulation of NPs. Once NPs enter the interstitial air spaces and are quickly taken up by alveolar cells, they are likely to induce toxic effects. In this review, we highlight the different aspects of lung toxicity resulting from NP exposure, such as generation of oxidative stress, DNA damage and inflammation leading to fibrosis and pneumoconiosis, and the underlying mechanisms causing pulmonary toxicity.

  19. Photosensitive Fluorescent Dye Contributes to Phototoxicity and Inflammatory Responses of Dye-doped Silica NPs in Cells and Mice

    PubMed Central

    Zhao, Yang; Ye, Yan; Zhou, Xikun; Chen, Jiao; Jin, Yuihui; Hanson, Aaron; Zhao, Julia Xiaojun; Wu, Min

    2014-01-01

    Dye-doped fluorescent silica nanoparticles provide highly intense and photostable fluorescence signals. However, some dopant dye molecules are photosensitive. A widely-used photosensitive fluorescent dopant, RuBpy, was chosen to systematically investigate the phototoxicity of the dye-doped silica nanoparticles (NPs). We investigated cell viability, DNA damage, and Reactive Oxygen Species (ROS) levels in alveolar macrophages using the dye-doped NPs with or without irradiation. Our results showed that the RuBpy-doped silica NPs could induce significant amount of ROS, DNA damage, apoptosis and impaired proliferation in MH-S cells. In vivo studies in mice showed that RuBpy-doped silica NPs induced significant inflammatory cytokine production and lowered expression in signaling proteins such as ERK1/2 and NF-κB as well as increased lung injury determined by myeloperoxidase and lipid peroxidation. Strikingly, we also found that both RuBpy alone and NPs induced systemic signaling activation in the kidney compared to the liver and lung where showed highly selective signaling patterns, which is more pronounced than RuBpy-doped silica NPs. Moreover, we discovered a critical biomarker (e.g., HMGB1) for silica NPs-induced stress and toxicity and demonstrated differentially-regulated response patterns in various organs. Our results indicate for the first time that the RuBpy-doped silica NPs may impose less inflammatory responses but stronger thermotherapeutic effects on target cells in animals than naked NPs in a time- and dose-dependent manner. PMID:24578727

  20. 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.

  1. Hydroquinone-assisted synthesis of branched au-ag nanoparticles with polydopamine coating as highly efficient photothermal agents.

    PubMed

    Li, Jing; Wang, Wenjing; Zhao, Liang; Rong, Li; Lan, Shijie; Sun, Hongchen; Zhang, Hao; Yang, Bai

    2015-06-03

    Despite the success of galvanic replacement in preparing hollow nanostructures with diversified morphologies via the replacement reaction between sacrificial metal nanoparticles (NPs) seeds and less active metal ions, limited advances are made for producing branched alloy nanostructures. In this paper, we report an extended galvanic replacement for preparing branched Au-Ag NPs with Au-rich core and Ag branches using hydroquinone (HQ) as the reductant. In the presence of HQ, the preformed Ag seeds are replaceable by Au and, in turn, supply the growth of Ag branches. By altering the feed ratio of Ag seeds, HAuCl4, and HQ, the size and morphology of the NPs are tunable. Accordingly, the surface plasmon resonance absorption is tuned to near-infrared (NIR) region, making the branched NPs as potential materials in photothermal therapy. The branched NPs are further coated with polydopamine (PDA) shell via dopamine polymerization at room temperature. In comparison with bare NPs, PDA-coated branched Au-Ag (Au-Ag@PDA) NPs exhibit improved stability, biocompatibility, and photothermal performance. In vitro experiments indicate that the branched Au-Ag@PDA NPs are competitive agents for photothermal ablation of cancer cells.

  2. Synthesis of fluorescent and low cytotoxicity phenol formaldehyde resin (PFR)@Ag composites for cell imaging and antibacterial activity.

    PubMed

    Yang, Ping; Dong, Hao; Xia, Jun; Xu, Andong; Shi, Jianjun; He, Jie; Ding, Jianzhong; Li, Dewei

    2015-12-01

    Ag nanoparticles (NPs) were loaded onto the surface of phenol formaldehyde resin (PFR) NPs without any reducing agent. The as-synthesized PFR@Ag composites have low cytotoxicity, which makes them promising antibacterial agents. Furthermore, the good fluorescence of PFR could be used for cell imaging.

  3. 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.

  4. Green Synthesized Silver Nanoparticles Exhibit Reduced Toxicity to Mammalian Cells and Retain Antimicrobial Activity

    EPA Science Inventory

    The interest in silver nanoparticles (AgNPs) and silver nanomaterial stems from their antimicrobial properties. AgNPs are being added to clothing, paint, refrigerators, washing machines and a variety of other commercially available items. Recent in vitro and in vivo studies, howe...

  5. Optimization of ZnO-NPs to Investigate Their Safe Application by Assessing Their Effect on Soil Nematode Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Gupta, Shruti; Kushwah, Tanuja; Vishwakarma, Ashutosh; Yadav, Shweta

    2015-07-01

    Zinc oxide nanoparticles (ZnO-NPs) are increasingly receiving attention due to their widespread application in cosmetics, pigments and coatings. This has raised concerns in the public and scientific communities regarding their unexpected health effects. Toxicity effect of ZnO-NPs on the environment was assessed in the present study using Caenorhabditis elegans. Multiple toxicity end points including their mortality, behaviour, reproduction, in vitro distribution and expression of stress response mtl-1 and sod-1 genes were observed to evaluate safe application of ZnO-NPs. C. elegans were exposed to 10, 50, and 100 nm ZnO-NPs (0.1 to 2.0 g/l). Application of 10 nm ≥0.7g/l adversely affects the survivability of worms and was significantly not affected with exposure of 50 and 100 nm ≤1.0 g/l. However, reproduction was affected at much low concentration as compared to their survivability. LC50 was recorded 1.0 ± 0.06 (g/l) for 100 nm, 0.90 ± 0.60 for 50 nm and 0.620 ± 0.08 for 10 nm. Expression of mtl-1 and sod-1 was significantly increased with application of 10 nm ≥0.7g/l and significantly unaffected with exposure of 50 and 100 nm at the same concentration. ZnO-NPs (10 nm) had shown even distribution extended nearly the entire length of the body. The distribution pattern of ZnO-NPs indicates that the intestine is the major target tissues for NP toxicity. Study demonstrates that small-sized (10 nm) ZnO-NPs ≥0.7g/l is more toxic than larger-sized particles. This may be suggested on the basis of available data; application of 50 and 100 nm ≤1.0 g/l ZnO-NPs may be used to the environment as this shows no significant toxicity. However, further calibration is warranted to explore safe dose on soil compartments prior to their field application.

  6. The effect of Fe segregation on the photocatalytic growth of Ag nanoparticles on rutile TiO2(001)

    NASA Astrophysics Data System (ADS)

    Busiakiewicz, Adam; Kisielewska, Aneta; Piwoński, Ireneusz; Batory, Damian

    2017-04-01

    The photocatalytic growth of silver nanoparticles (AgNPs) on rutile TiO2(001) and Fe-modified rutile TiO2(001) monocrystals was investigated. Various amount of Fe was segregated in a controlled way from the doped TiO2 substrates in ultra-high vacuum conditions resulting in low- medium- and high- content of Fe on TiO2 substrates. AgNPs were grown on pristine TiO2 and substrates containing Fe by photoreduction of Ag+ ions under UV illumination. It was found that the size of AgNPs was larger on Fe/TiO2 than on TiO2 while the surface density exhibited the opposite behavior - a large number of AgNPs were present on the TiO2 surface but only a few AgNPs were visible on the Fe/TiO2 substrates. The reason for the differences in size and number of AgNPs on TiO2 and Fe/TiO2 is the limited access of Ag+ to the TiO2 surface caused by the large number of Fe grains segregated onto the TiO2 surface. Another possible reason for the various AgNPs morphologies is alteration in the mechanism of Ag+ photoreduction caused by iron present as Fe3+ ions and by newly formed AgNPs playing the role of electron traps. The surface elemental analysis of the investigated materials was performed with the use of X-ray photoelectron spectroscopy (XPS) and confirmed the composition of AgNPs/Fe/TiO2 systems. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed sizes, morphology and distribution of the nanostructures.

  7. Ag-Fe2O3 nanocomposites with enhanced catalytic activity for reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Liu, Shiben; Chen, Yingjie; Dong, Lifeng

    2016-07-01

    Hybrid nanostructures can be multifunctional and even possess enhanced properties. Ag-Fe2O3 nanocomposites and Ag nanoparticles (NPs) were fabricated and applied to catalyze the reduction of 4-nitrophenol. Compared with Ag NPs, Ag-Fe2O3 nanocomposites demonstrated enhanced catalytic activities. Furthermore, due to their magnetic properties, Ag-Fe2O3 nanocomposites could be easily separated from the reaction mixture and recycled through an external magnetic field. These findings will help us design hybrid nanostructures with catalytic activity and explore other potential applications of magnetic nanocomposites.

  8. Photocatalytic oxidation removal of Hg0 using ternary Ag/AgI-Ag2CO3 hybrids in wet scrubbing process under fluorescent light

    NASA Astrophysics Data System (ADS)

    Zhang, Anchao; Zhang, Lixiang; Chen, Xiaozhuan; Zhu, Qifeng; Liu, Zhichao; Xiang, Jun

    2017-01-01

    A series of ternary Ag/AgI-Ag2CO3 photocatalysts synthesized using a facile coprecipitation method were employed to investigate their performances of Hg0 removal in a wet scrubbing reactor. The hybrids were characterized by N2 adsorption-desorption, XRD, SEM-EDS, HRTEM, XPS, DRS and ESR. The photocatalytic activities of Hg0 removal were evaluated under fluorescent light. The results showed that AgI content, fluorescent light irradiation, reaction temperature all showed significant influences on Hg0 removal. NO exhibited significant effect on Hg0 removal in comparison to SO2. Among these ternary Ag/AgI-Ag2CO3 hybrids, Ag/AgI(0.1)-Ag2CO3 showed the highest Hg0 removal efficiency, which could be ascribed to the effective separation of photogenerated electron-hole pairs between AgI and Ag2CO3 and the surface plasmon resonance (SPR) effect in the visible region by metallic silver nanoparticles (Ag0 NPs). The trapping studies of reactive radicals showed that the superoxide radicals (rad O2-) may play a key role in Hg0 removal under fluorescent light. According to the experimental and characterization results, a possible photocatalytic oxidation mechanism for enhanced Hg0 removal over Ag/AgI(0.1)-Ag2CO3 hybrid under fluorescent light was proposed.

  9. Green fabrication of quaternized chitosan/rectorite/Ag NP nanocomposites with antimicrobial activity.

    PubMed

    Luo, Jiwen; Xie, Meijia; Wang, Xiaoying

    2014-02-01

    Silver nanoparticles (Ag NPs) were synthesized rapidly in one pot via the Tollens reaction, in which quaternized chitosan (QCS) and rectorite (REC) acted as the reducing and stabilizing agent, while other chemical reducing and stabilizing agents and the surfactant were not included. X-ray diffraction, scanning electron microscopy and transmission electron microscopy results showed that spherical Ag NPs with uniform sizes were obtained, the layers of clay were peeled and thus exfoliated QCS/REC/Ag NP (QCRAg) nanocomposite was achieved. Moreover, Ag NPs dispersed well in the exfoliated nanocomposite matrix, some Ag NPs even entered into the interlayer of REC. QCRAg nanocomposites showed strong antimicrobial activity; the lowest minimum inhibitory concentration against Staphyloccocus aureus was only 0.0001% (w/v). The study reveals that the obtained QCRAg nanocomposites have great potential for biomedical applications.

  10. Bacterial toxicity/compatibility of platinum nanospheres, nanocuboids and nanoflowers

    PubMed Central

    Gopal, Judy; Hasan, Nazim; Manikandan, M.; Wu, Hui-Fen

    2013-01-01

    For the first time, we have investigated the bacterial toxicity or compatibility properties of Pt nanoparticles (NPs) with different sizes (P1, P2, P3, P4 and P5). The bacterio-toxic or compatible properties of these five different sized Pt NPs with the clinical pathogen, Pseudomonas aeruginosa were explored by many analytical methods such as the conventional plate count method, matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS), fluorescence microscopy and fluorescence sensoring techniques. The results revealed that the 1–3 nm sized (P1 and P2) Pt NPs showed bacterio-toxic properties while the 4–21 nm (P3, P4 and P5) Pt NPs exhibited bacterio-compatible properties. This is the first study which reports the bacterial toxicity of Pt NPs. The information released from this study is significantly important to future clinical, medical, biological and biomedical applications of Pt NPs. PMID:23405274

  11. Ag-nanoparticle-decorated porous ZnO-nanosheets grafted on a carbon fiber cloth as effective SERS substrates

    NASA Astrophysics Data System (ADS)

    Wang, Zhiwei; Meng, Guowen; Huang, Zhulin; Li, Zhongbo; Zhou, Qitao

    2014-11-01

    We report on the large-scale synthesis of Ag-nanoparticle (Ag-NP) decorated ZnO-mesoporous-nanosheets (NSs) grafted on a flexible carbon fiber cloth (CFC), as sensitive and reproducible surface enhanced Raman scattering (SERS) substrates with excellent flexibility. The composite SERS-substrates are achieved by a combination of atomic layer deposition of ZnO-seeds on each fiber of the CFC (denoted as ZnO-seeds@CFC), chemical bath deposition and subsequent pyrolysis for the creation of ZnO-mesoporous-NSs grafted on ZnO-seeds@CFC, and ion-sputtering of Ag-NPs on the ZnO-mesoporous-NSs. As abundant SERS ``hot spots'' are generated from the electromagnetic coupling of the densely distributed Ag-NPs, and the semiconducting ZnO-mesoporous-NSs also have chemical supporting enhancement and distinct molecule adsorbing abilities, the composite SERS-substrates demonstrate high SERS-sensitivity with good signal reproducibility. As a trial for potential applications, the composite SERS-substrates were used to identify pesticides and highly toxic polychlorinated biphenyls (PCBs), and low concentrations down to 10-7 M for methyl parathion and 5 × 10-6 M for PCB-77 were reached, respectively, showing promising potential for the SERS-based rapid detection of toxic organic pollutants in the environment.We report on the large-scale synthesis of Ag-nanoparticle (Ag-NP) decorated ZnO-mesoporous-nanosheets (NSs) grafted on a flexible carbon fiber cloth (CFC), as sensitive and reproducible surface enhanced Raman scattering (SERS) substrates with excellent flexibility. The composite SERS-substrates are achieved by a combination of atomic layer deposition of ZnO-seeds on each fiber of the CFC (denoted as ZnO-seeds@CFC), chemical bath deposition and subsequent pyrolysis for the creation of ZnO-mesoporous-NSs grafted on ZnO-seeds@CFC, and ion-sputtering of Ag-NPs on the ZnO-mesoporous-NSs. As abundant SERS ``hot spots'' are generated from the electromagnetic coupling of the densely

  12. The neglected nano-specific toxicity of ZnO nanoparticles in the yeast Saccharomyces cerevisiae.

    PubMed

    Zhang, Weicheng; Bao, Shaopan; Fang, Tao

    2016-04-20

    Nanoparticles (NPs) with unique physicochemical properties induce nano-specific (excess) toxicity in organisms compared with their bulk counterparts. Evaluation and consideration of nano-specific toxicity are meaningful for the safe design and environmental risk assessment of NPs. However, ZnO NPs have been reported to lack excess toxicity for diverse organisms. In the present study, the nano-specific toxicity of ZnO NPs was evaluated in the yeast Saccharomyces cerevisiae. Nano-specific toxicity of ZnO NPs was not observed in the wild type yeast. However, the ZnO NPs induced very similar nano-specific toxicities in the three mutants with comparable log Te ((particle)) values (0.64 vs 0.65 vs 0.62), suggesting that the mutants were more sensitive and specific for the NPs' nano-specific toxicity. The toxic effects in the yeast were slightly attributable to dissolved zinc ions from the ZnO (nano or bulk) particles. Oxidative damage and mechanical damage contributed to the toxic effect of the ZnO particles. The mechanism of mechanical damage is proposed to be an inherent characteristic underlying the nano-specific toxicity in the mutants. The log Te ((particle)) was a useful parameter for evaluation of NPs nano-specific toxicity, whereas log Te ((ion)) efficiently determined the NPs toxicity associated with released ions.

  13. Enhanced chemiluminescence of the luminol-AgNO3 system by Ag nanoparticles.

    PubMed

    Li, Shifeng; Sun, Huimin; Wang, Dong; Hong, Jianguo; Tao, Shanjun; Yu, Haiyin; Wang, Xiuhua; Wei, Xianwen

    2012-01-01

    The oxidation reaction of luminol with AgNO(3) can produce chemiluminescence (CL) in the presence of silver nanoparticles (NPs) in alkaline solution. Based on the studies of UV-vis absorption spectra, photoluminescence (PL) spectra and CL spectra, a CL enhancement mechanism is proposed. The CL emission spectrum of the luminol-AgNO(3)-Ag NPs system indicated that the luminophore was still 3-aminophthalate. On injection of silver nanoparticles into the mixture of luminol and AgNO(3), they catalysed the reduction of AgNO(3) by luminol. The product luminol radicals reacted with the dissolved oxygen, to produce a strong CL emission. As a result, the CL intensity was substantially increased. Moreover, the influences of 18 amino acids, e.g. cystine, tyrosine and asparagine, and 25 organic compounds, including gallic acid, tannic acid and hydroquinone, on the luminol-AgNO(3)-Ag NPs CL system were studied by a flow-injection procedure, which led to an effective method for detecting these compounds.

  14. 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.

  15. 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

  16. Plasmon enhanced CdS-quantum dot sensitized solar cell using ZnO nanorods array deposited with Ag nanoparticles as photoanode

    NASA Astrophysics Data System (ADS)

    Eskandari, M.; Ahmadi, V.; Yousefi rad, M.; Kohnehpoushi, S.

    2015-04-01

    CdS-quantum dot sensitized solar cell using ZnO nanorods (ZnO NRs) array deposited with Ag nanoparticles (Ag NPs) as photoanode was fabricated. Light absorption effect of Ag NPs on improvement of the cell performance was investigated. Performance improvement of metal nanoparticles (MNPs) was controlled by the structure design and architecture. Different decorations and densities of Ag NPs were utilized on the photoanode. Results showed that using 5% Ag NPs in the photoanode results in the increased efficiency, fill factor, and circuit current density from 0.28% to 0.60%, 0.22 to 0.29, and 2.18 mA/cm2 to 3.25 mA/cm2, respectively. Also, incident photon-to-current efficiencies (IPCE) results showed that cell performance improvement is related to enhanced absorption in the photoanode, which is because of the surface plasmonic resonance and light scattering of Ag NPs in the photoanode. Measurements of electrochemical impedance spectroscopy revealed that hole transfer kinetics increases with introduction of Ag NPs into photoanode. Also, it is shown that chemical capacitance increases with introduction of Ag NPs. Such increase can be attributed to the surface palsmonic resonance of Ag NPs which leads to absorption of more light in the photoanode and generation of more photoelectron in the photoanode.

  17. 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.

  18. Influence of size, shape and core–shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiOx

    PubMed Central

    Pinotti, Daniele; Spadaro, Maria Chiara; Paolicelli, Guido; Grillo, Vincenzo; Valeri, Sergio; Pasquali, Luca; Bergamini, Luca; Corni, Stefano

    2015-01-01

    Summary Ag and Ag@MgO core–shell nanoparticles (NPs) with a diameter of d = 3–10 nm were obtained by physical synthesis methods and deposited on Si with its native ultrathin oxide layer SiOx (Si/SiOx). Scanning electron microscopy and transmission electron microscopy (TEM) images of bare Ag NPs revealed the presence of small NP aggregates caused by diffusion on the surface and agglomeration. Atomic resolution TEM gave evidence of the presence of crystalline multidomains in the NPs, which were due to aggregation and multitwinning occurring during NP growth in the nanocluster source. Co-deposition of Ag NPs and Mg atoms in an oxygen atmosphere gave rise to formation of a MgO shell matrix surrounding the Ag NPs. The behaviour of the surface plasmon resonance (SPR) excitation in surface differential reflectivity (SDR) spectra with p-polarised light was investigated for bare Ag and Ag@MgO NPs. It was shown that the presence of MgO around the Ag NPs caused a red shift of the plasmon excitation, and served to preserve its existence after prolonged (five months) exposure to air, realizing the possibility of technological applications in plasmonic devices. The Ag NP and Ag@MgO NP film features in the SDR spectra could be reproduced by classical electrodynamics simulations by treating the NP-containing layer as an effective Maxwell Garnett medium. The simulations gave results in agreement with the experiments when accounting for the experimentally observed aggregation. PMID:25821680

  19. Self-Assembly of Ag Nanoparticles Induced by Centrifuging and Broken by Silanization.

    PubMed

    Yang, Ping; Zhang, Yulan

    2015-08-01

    A novel method was developed to assemble Ag nanoparticles (NPs) into chain-like structures. The assembly of the NPs was created by suspending in an ethanol and water solution as well as centrifuging at a high speed (a force of more than 29 Kg for the NPs with an average diameter of 18 nm). The composition of solvents and centrifuged speeds of samples play important roles for the formation of regular assemblies. The number of Ag NPs in the chain-like assemblies was adjusted by changing centrifuging forces. The assemblies of the NPs were fixed by a SiO2 coating through a St6ber synthesis. In addition, the assemblies were broken through a silanization process because of partially hydrolyzed tetraethyl-orthosilicate molecules adsorbed on the surface of Ag NPs to form a SiO2 layer opposite aggregation. A slow silanization process made Ag NPs monodispersed in solutions, in which Ag/SiO2 core/shell NPs were created.

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

    PubMed

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

    2016-05-14

    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.

  1. Electrochemical detection of Cu2+ through Ag nanoparticle assembly regulated by copper-catalyzed oxidation of cysteamine.

    PubMed

    Cui, Lin; Wu, Jie; Li, Jie; Ge, Yanqiu; Ju, Huangxian

    2014-05-15

    A highly sensitive and selective electrochemical sensor was developed for the detection of Cu(2+) by the assembly of Ag nanoparticles (AgNPs) at dithiobis[succinimidylpropionate] encapsulated Au nanoparticles (DSP-AuNPs), which was regulated by copper-catalyzed oxidation of cysteamine (Cys). The electrochemical sensor was constructed by layer-by-layer modification of glassy carbon electrode with carbon nanotubes, poly(amidoamine) dendrimers and DSP-AuNPs. In the absence of Cu(2+), Cys could bind to the surface of citrate-stabilized AgNPs via Ag-S bond, thus AgNPs could be assembled on the sensor surface through the reaction between DSP and Cys. In contrast, the copper-catalyzed oxidation of Cys by dissolved oxygen in the presence of Cu(2+) inhibited the Cys-induced aggregation of AgNPs, leading to the decrease of the electrochemical stripping signal of AgNPs. Under the optimized conditions, this method could detect Cu(2+) in the range of 1.0-1000 nM with a detection limit of 0.48 nM. The proposed Cu(2+) sensor showed good reproducibility, stability and selectivity. It has been satisfactorily applied to determine Cu(2+) in water samples.

  2. Synthesis of metal oxide nanoparticles (CuO and ZnO NPs) via biological template and their optical sensor applications

    NASA Astrophysics Data System (ADS)

    Maruthupandy, Muthuchamy; Zuo, Yong; Chen, Jing-Shuai; Song, Ji-Ming; Niu, He-Lin; Mao, Chang-Jie; Zhang, Sheng-Yi; Shen, Yu-Hua

    2017-03-01

    The present study is focused on employing Camellia japonica leaf extract as inductive and stabilizing agent to synthesis CuO and ZnO nanoparticles (NPs). The chemicals, such as (Cu(NO3)2·3H2O) and (Zn(NO3)2·6H2O) were converted into copper and zinc ions, respectively because of the different natural products present in the C. japonica leaf extract. The UV-vis spectra of CuO and ZnO NPs showed absorption peak at 290 nm and 301 nm, respectively. The XRD result revealed crystalline nature of the metal oxide NPs and the TEM images indicated that average sizes of the synthesized CuO and ZnO NPs were ∼17 nm and ∼20 nm, respectively. The FTIR spectra of C. japonica leaf extract showed the presence of organic groups, such as, sbnd OH, sbnd Csbnd N, and N-H, which would be responsible for forming CuO and ZnO NPs. The synthesized CuO and ZnO NPs were tested for the optical sensing of metal ions, viz. Li+ and Ag+ that illustrated excellent outcome and hence this method offers a novel lane for the synthesis of metal oxide NPs, which can be used as optical sensor for the detection of metal ions.

  3. β-CD Dimer-immobilized Ag Assembly Embedded Silica Nanoparticles for Sensitive Detection of Polycyclic Aromatic Hydrocarbons

    NASA Astrophysics Data System (ADS)

    Hahm, Eunil; Jeong, Daham; Cha, Myeong Geun; Choi, Jae Min; Pham, Xuan-Hung; Kim, Hyung-Mo; Kim, Hwanhee; Lee, Yoon-Sik; Jeong, Dae Hong; Jung, Seunho; Jun, Bong-Hyun

    2016-05-01

    We designed a β-CD dimer on silver nanoparticles embedded with silica nanoparticles (Ag@SiO2 NPs) structure to detect polycyclic aromatic hydrocarbons (PAHs). Silica NPs were utilized as a template for embedding silver NPs to create hot spot structures and enhance the surface-enhanced Raman scattering (SERS) signal, and a thioether-bridged dimeric β-CD was immobilized on Ag NPs to capture PAHs. The assembled Ag NPs on silica NPs were confirmed by TEM and the presence of β-CD dimer on Ag@SiO2 was confirmed by UV-vis and attenuated total reflection-Fourier transform infrared spectroscopy. The β-CD dimer@Ag@SiO2 NPs were used as SERS substrate for detecting perylene, a PAH, directly and in a wide linearity range of 10‑7 M to 10‑2 M with a low detection limit of 10‑8 M. Also, the β-CD dimer@Ag@SiO2 NPs exhibited 1000-fold greater sensitivity than Ag@SiO2 NPs in terms of their perylene detection limit. Furthermore, we demonstrated the possibility of detecting various PAH compounds using the β-CD dimer@Ag@SiO2 NPs as a multiplex detection tool. Various PAH compounds with the NPs exhibited their distinct SERS bands by the ratio of each PAHs. This approach of utilizing the assembled structure and the ligands to recognize target has potential for use in sensitive analytical sensors.

  4. β-CD Dimer-immobilized Ag Assembly Embedded Silica Nanoparticles for Sensitive Detection of Polycyclic Aromatic Hydrocarbons

    PubMed Central

    Hahm, Eunil; Jeong, Daham; Cha, Myeong Geun; Choi, Jae Min; Pham, Xuan-Hung; Kim, Hyung-Mo; Kim, Hwanhee; Lee, Yoon-Sik; Jeong, Dae Hong; Jung, Seunho; Jun, Bong-Hyun

    2016-01-01

    We designed a β-CD dimer on silver nanoparticles embedded with silica nanoparticles (Ag@SiO2 NPs) structure to detect polycyclic aromatic hydrocarbons (PAHs). Silica NPs were utilized as a template for embedding silver NPs to create hot spot structures and enhance the surface-enhanced Raman scattering (SERS) signal, and a thioether-bridged dimeric β-CD was immobilized on Ag NPs to capture PAHs. The assembled Ag NPs on silica NPs were confirmed by TEM and the presence of β-CD dimer on Ag@SiO2 was confirmed by UV-vis and attenuated total reflection-Fourier transform infrared spectroscopy. The β-CD dimer@Ag@SiO2 NPs were used as SERS substrate for detecting perylene, a PAH, directly and in a wide linearity range of 10−7 M to 10−2 M with a low detection limit of 10−8 M. Also, the β-CD dimer@Ag@SiO2 NPs exhibited 1000-fold greater sensitivity than Ag@SiO2 NPs in terms of their perylene detection limit. Furthermore, we demonstrated the possibility of detecting various PAH compounds using the β-CD dimer@Ag@SiO2 NPs as a multiplex detection tool. Various PAH compounds with the NPs exhibited their distinct SERS bands by the ratio of each PAHs. This approach of utilizing the assembled structure and the ligands to recognize target has potential for use in sensitive analytical sensors. PMID:27184729

  5. Ag Nanoparticle-Grafted PAN-Nanohump Array Films with 3D High-Density Hot Spots as Flexible and Reliable SERS Substrates.

    PubMed

    Li, Zhongbo; Meng, Guowen; Huang, Qing; Hu, Xiaoye; He, Xuan; Tang, Haibin; Wang, Zhiwei; Li, Fadi

    2015-10-28

    A facile fabrication approach of large-scale flexible films is reported, with one surface side consisting of Ag-nanoparticle (Ag-NP) decorated polyacrylonitrile (PAN) nanohump (denoted as Ag-NPs@PAN-nanohump) arrays. This is achieved via molding PAN films with ordered nanohump arrays on one side and then sputtering much smaller Ag-NPs onto each of the PAN-nanohumps. Surface-enhanced Raman scattering (SERS) activity of the Ag-NPs@PAN-nanohump array films can be improved by curving the flexible PAN film with ordered nanohump arrays during the Ag-sputtering process to increase the density of the Ag-NPs on the sidewalls of the PAN-nanohumps. More 3D hot spots are thus achieved on a large-scale. The Ag-NPs@PAN-nanohump array films show high SERS activity with good Raman signal reproducibility for Rhodamine 6G probe molecules. To trial their practical application, the Ag-NPs@PAN-nanohump array films are employed as SERS substrates for trace detection of trinitrotoluene and a congener of polychlorinated biphenyls. A lower detection limit of 10(-12) m and 10(-5) m can be achieved, respectively. Furthermore, the flexible Ag-NPs@PAN-nanohump array films can also be utilized as swabs to probe traces of methyl parathion on the surface of fruits such as apples. The as-fabricated SERS substrates therefore have promising potential for applications in rapid safety inspection and environmental protection.

  6. Ag nanoparticles enhanced near-IR emission from Er3+ ions doped glasses

    NASA Astrophysics Data System (ADS)

    Qi, Jiani; Xu, Tiefeng; Wu, Yi; Shen, Xiang; Dai, Shixun; Xu, Yinsheng

    2013-10-01

    Vitreous materials containing rare-earth (RE) ions and metallic nanoparticles (NPs) attract considerable interest because the presence of the NPs may lead to an intensification of luminescence. In this work, the characteristics of 1.54 μm luminescence for the Er3+ ions doped bismuthate glasses containing Ag NPs were studied under 980 nm excitation. The surface plasmon resonance (SPR) band of Ag NPs appears from 500 to 1500 nm. Transmission electron microscopic (TEM) image reveals that the Ag NPs are dispersed homogeneously with the size from 2 to 7 nm. The strength parameters Ωt(t = 2, 4, 6), spontaneous emission probability (A), radiative lifetime (τ) and stimulated emission section (σem) of Er3+ ions were calculated by the Judd-Ofelt theory. When the glass contains 0.2 wt% AgCl, the 1.54 μm fluorescence intensity of Er3+ reaches a maximum value, which is 7.2 times higher than that of glass without Ag NPs. The Ag NPs embedded glasses show significantly fluorescence enhancement of Er3+ ions by local field enhancement from SPR.

  7. Controlled joining of Ag nanoparticles with femtosecond laser radiation

    NASA Astrophysics Data System (ADS)

    Huang, H.; Liu, L.; Peng, P.; Hu, A.; Duley, W. W.; Zhou, Y.

    2012-12-01

    We show that it is possible to tailor the gap separation and interface geometry between adjacent Ag nanoparticles (NPs) by controlling fluence when irradiating with pulses from a fs laser. Unirradiated samples extracted from aqueous solution consist of networks of Ag NPs coated with polyvinylpyrrolidone (PVP). At low laser fluence, bonding between NPs occurs via the formation of an intervening hydrogenated amorphous carbon (α-C:H) layer resulting from the laser-induced decomposition of PVP. This occurs when electrons are emitted at hot-spots created by the trapping of plasmons. The thickness of the α-C:H layer determines the minimum separation between NPs. Ag NPs with different contact geometries can be produced by irradiation of the networks in solution at fluences exceeding the threshold for the formation of α-C:H. At fluences between 200 and 380 μJ/cm2, the α-C:H interface layer is replaced with a metallic neck. Surface enhanced Raman scattering (SERS) has been used to quantify the electromagnetic field enhancement in joined NP samples. We find that Ag NPs bonded by α-C:H and exhibiting a narrow gap possess the highest SERS enhancement.

  8. Long-term effects of cupric oxide nanoparticles (CuO NPs) on the performance, microbial community and enzymatic activity of activated sludge in a sequencing batch reactor.

    PubMed

    Wang, Sen; Li, Zhiwei; Gao, Mengchun; She, Zonglian; Ma, Bingrui; Guo, Liang; Zheng, Dong; Zhao, Yangguo; Jin, Chunji; Wang, Xuejiao; Gao, Feng

    2017-02-01

    The long-term effects of cupric oxide nanoparticles (CuO NPs) on the performance, microbial activity and microbial community of activated sludge were investigated in a sequencing batch reactor (SBR). The SBR performance had no evident change at 0-10 mg/L CuO NPs, whereas the CuO NPs concentration at 30-60 mg/L affected the COD, NH4(+)-N and soluble orthophosphate (SOP) removal, nitrogen and phosphorus removal rate and microbial enzymatic activity of activated sludge. Some CuO NPs might be absorbed on the surface of activated sludge or penetrate the microbial cytomembrane into the microbial cell interior of activated sludge. Compared to 0 mg/L CuO NPs, the reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release increased by 43.6% and 56.4% at 60 mg/L CuO NPs, respectively. The variations of ROS production and LDH release demonstrated that CuO NPs could induce the toxicity towards the microorganisms and destroy the integrity of microbial cytomembrane in the activated sludge. High throughput sequencing of 16S rDNA indicated that CuO NPs could evidently impact on the microbial richness, diversity and composition of activated sludge in the SBR.

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

    PubMed Central

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

    2016-01-01

    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. PMID:28335245

  10. 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.

  11. 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.

    PubMed

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

    2015-02-25

    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.

  12. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)

    PubMed Central

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-01-01

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability. PMID:27687573

  13. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS)

    NASA Astrophysics Data System (ADS)

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-09-01

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.

  14. Use of Single-Layer g-C3N4/Ag Hybrids for Surface-Enhanced Raman Scattering (SERS).

    PubMed

    Jiang, Jizhou; Zou, Jing; Wee, Andrew Thye Shen; Zhang, Wenjing

    2016-09-30

    Surface-enhanced Raman scattering (SERS) substrates with high activity and stability are desirable for SERS sensing. Here, we report a new single atomic layer graphitic-C3N4 (S-g-C3N4) and Ag nanoparticles (NPs) hybrid as high-performance SERS substrates. The SERS mechanism of the highly stable S-g-C3N4/Ag substrates was systematically investigated by a combination of experiments and theoretical calculations. From the results of XPS and Raman spectroscopies, it was found that there was a strong interaction between S-g-C3N4 and Ag NPs, which facilitates the uniform distribution of Ag NPs over the edges and surfaces of S-g-C3N4 nanosheets, and induces a charge transfer from S-g-C3N4 to the oxidizing agent through the silver surface, ultimately protecting Ag NPs from oxidation. Based on the theoretical calculations, we found that the net surface charge of the Ag atoms on the S-g-C3N4/Ag substrates was positive and the Ag NPs presented high dispersibility, suggesting that the Ag atoms on the S-g-C3N4/Ag substrates were not likely to be oxidized, thereby ensuring the high stability of the S-g-C3N4/Ag substrate. An understanding of the stability mechanism in this system can be helpful for developing other effective SERS substrates with long-term stability.

  15. Lectin coated MgO nanoparticle: its toxicity, antileishmanial activity, and macrophage activation.

    PubMed

    Jebali, Ali; Hekmatimoghaddam, Seyedhossein; Kazemi, Bahram; Allaveisie, Azra; Masoudi, Alireza; Daliri, Karim; Sedighi, Najme; Ranjbari, Javad

    2014-10-01

    The purpose of this research was to evaluate toxicity of uncoated magnesium oxide nanoparticles (MgO NPs), MgO NPs coated with Peanut agglutinin (PNA) lectin, and PNA alone on the promastigotes of Leishmania major (L. major) and macrophages of BALB/c mice. On the other hand, antileishmanial property of uncoated MgO NPs, lectin coated MgO NPs, and PNA lectin alone was evaluated, and also macrophage activation was investigated after treatment with these materials by measurement of nitrite, H2O2, and some interleukins. This study showed that PNA lectin and lectin coated MgO NPs had approximately no toxicity on L. major and macrophages, but some toxic effects were observed for uncoated MgO NPs, especially at concentration of 500 µg/mL. Interestingly, lectin coated MgO NPs had the highest antileishmanial activity and macrophage activation, compared with uncoated MgO NPs and PNA lectin.

  16. Luminescent Ag-doped In2S3 nanoparticles stabilized by mercaptoacetate in water and glycerol

    NASA Astrophysics Data System (ADS)

    Raevskaya, Alexandra E.; Ivanchenko, Maria V.; Stroyuk, Oleksandr L.; Kuchmiy, Stepan Ya.; Plyusnin, Victor F.

    2015-03-01

    Colloidal nanoparticles (NPs) of tetragonal β-In2S3 were stabilized in water and glycerol by mercaptoacetate anions. Doping of In2S3 NPs with AgI cations at the time of the synthesis imparts the NPs with the photoluminescence (PL) in the visible part of the spectrum. The doping results also in a shift of the absorption threshold and the PL band maximum to longer wavelengths proportional to the AgI content. The PL band maximum of AgI-doped In2S3 NPs can be varied from 575-580 to 760-765 nm by augmenting the silver(I) amount and the duration and temperature of the post-synthesis aging. The average radiative life-time of AgI-doped In2S3 NPs also depends on the silver(I) content and reaches the maximal value, 960 ns, at a molar Ag:In ratio of 1:4. The maximal quantum yield of stationary PL, 12 %, is observed at this Ag:In ratio as well. Deposition of a ZnS "shell" on the surface of AgI-doped In2S3 NPs results in an increase of the PL quantum yield to 30 %.

  17. NPS-SCAT: Systems Engineering and Payload Subsystem Design, Integration, and Testing of NPS’ First CubeSat

    DTIC Science & Technology

    2010-06-01

    20 Figure 13 NPS-SCAT Prototype (From [39]) ..................................................................22 Figure 14 Pumpkin FM430 PCB...of a prototype unit by Alex Bein [39]. The initial prototype consisted of a Pumpkin CubeSat Kit that included a 1U Pumpkin Structure, Pumpkin Linear...NPS-SCAT satellite was the Microhard MHX-2420 2.4 GHz radio transceiver [39]. This component is strictly COTS and was marketed by the Pumpkin

  18. Ag-plasma modification enhances bone apposition around titanium dental implants: an animal study in Labrador dogs.

    PubMed

    Qiao, Shichong; Cao, Huiliang; Zhao, Xu; Lo, Hueiwen; Zhuang, Longfei; Gu, Yingxin; Shi, Junyu; Liu, Xuanyong; Lai, Hongchang

    2015-01-01

    Dental implants with proper antibacterial ability as well as ideal osseointegration are being actively pursued. The antimicrobial ability of titanium implants can be significantly enhanced via modification with silver nanoparticles (Ag NPs). However, the high mobility of Ag NPs results in their potential cytotoxicity. The silver plasma immersion ion-implantation (Ag-PIII) technique may remedy the defect. Accordingly, Ag-PIII technique was employed in this study in an attempt to reduce the mobility of Ag NPs and enhance osseointegration of sandblasted and acid-etched (SLA) dental implants. Briefly, 48 dental implants, divided equally into one control and three test groups (further treated by Ag-PIII technique with three different implantation parameters), were inserted in the mandibles of six Labrador dogs. Scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry were used to investigate the surface topography, chemical states, and silver release of SLA- and Ag-PIII-treated titanium dental implants. The implant stability quotient examination, Microcomputed tomography evaluation, histological observations, and histomorphometric analysis were performed to assess the osseointegration effect in vivo. The results demonstrated that normal soft tissue healing around dental implants was observed in all the groups, whereas the implant stability quotient values in Ag-PIII groups were higher than that in the SLA group. In addition, all the Ag-PIII groups, compared to the SLA-group, exhibited enhanced new bone formation, bone mineral density, and trabecular pattern. With regard to osteogenic indicators, the implants treated with Ag-PIII for 30 minutes and 60 minutes, with the diameter of the Ag NPs ranging from 5-25 nm, were better than those treated with Ag-PIII for 90 minutes, with the Ag NPs diameter out of that range. These results suggest that Ag-PIII technique can reduce the mobility of Ag NPs and enhance

  19. Ag-plasma modification enhances bone apposition around titanium dental implants: an animal study in Labrador dogs

    PubMed Central

    Qiao, Shichong; Cao, Huiliang; Zhao, Xu; Lo, Hueiwen; Zhuang, Longfei; Gu, Yingxin; Shi, Junyu; Liu, Xuanyong; Lai, Hongchang

    2015-01-01

    Dental implants with proper antibacterial ability as well as ideal osseointegration are being actively pursued. The antimicrobial ability of titanium implants can be significantly enhanced via modification with silver nanoparticles (Ag NPs). However, the high mobility of Ag NPs results in their potential cytotoxicity. The silver plasma immersion ion-implantation (Ag-PIII) technique may remedy the defect. Accordingly, Ag-PIII technique was employed in this study in an attempt to reduce the mobility of Ag NPs and enhance osseointegration of sandblasted and acid-etched (SLA) dental implants. Briefly, 48 dental implants, divided equally into one control and three test groups (further treated by Ag-PIII technique with three different implantation parameters), were inserted in the mandibles of six Labrador dogs. Scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry were used to investigate the surface topography, chemical states, and silver release of SLA- and Ag-PIII-treated titanium dental implants. The implant stability quotient examination, Microcomputed tomography evaluation, histological observations, and histomorphometric analysis were performed to assess the osseointegration effect in vivo. The results demonstrated that normal soft tissue healing around dental implants was observed in all the groups, whereas the implant stability quotient values in Ag-PIII groups were higher than that in the SLA group. In addition, all the Ag-PIII groups, compared to the SLA-group, exhibited enhanced new bone formation, bone mineral density, and trabecular pattern. With regard to osteogenic indicators, the implants treated with Ag-PIII for 30 minutes and 60 minutes, with the diameter of the Ag NPs ranging from 5–25 nm, were better than those treated with Ag-PIII for 90 minutes, with the Ag NPs diameter out of that range. These results suggest that Ag-PIII technique can reduce the mobility of Ag NPs and

  20. The valence band structure of Ag{sub x}Rh{sub 1–x} alloy nanoparticles

    SciTech Connect

    Yang, Anli; Sakata, Osami; Kusada, Kohei; Kobayashi, Hirokazu; Yayama, Tomoe; Ishimoto, Takayoshi; Yoshikawa, Hideki; Koyama, Michihisa; and others

    2014-10-13

    The valence band (VB) structures of face-centered-cubic Ag-Rh alloy nanoparticles (NPs), which are known to have excellent hydrogen-storage properties, were investigated using bulk-sensitive hard x-ray photoelectron spectroscopy. The observed VB spectra profiles of the Ag-Rh alloy NPs do not resemble simple linear combinations of the VB spectra of Ag and Rh NPs. The observed VB hybridization was qualitatively reproduced via a first-principles calculation. The electronic structure of the Ag{sub 0.5}Rh{sub 0.5} alloy NPs near the Fermi edge was strikingly similar to that of Pd NPs, whose superior hydrogen-storage properties are well known.

  1. Laminin Receptor-Avid Nanotherapeutic EGCg-AuNPs as a Potential Alternative Therapeutic Approach to Prevent Restenosis

    PubMed Central

    Khoobchandani, Menka; Katti, Kavita; Maxwell, Adam; Fay, William P.; Katti, Kattesh V.

    2016-01-01

    In our efforts to develop new approaches to treat and prevent human vascular diseases, we report herein our results on the proliferation and migration of human smooth muscles cells (SMCs) and endothelial cells (ECs) using epigallocatechin-3-gallate conjugated gold nanoparticles (EGCg-AuNPs) as possible alternatives to drug coated stents. Detailed in vitro stability studies of EGCg-AuNPs in various biological fluids, affinity and selectivity towards SMCs and ECs have been investigated. The EGCg-AuNPs showed selective inhibitory efficacy toward the migration of SMCs. However, the endothelial cells remained unaffected under similar experimental conditions. The cellular internalization studies have indicated that EGCg-AuNPs internalize into the SMCs and ECs within short periods of time through laminin receptor mediated endocytosis mode. Favorable toxicity profiles and selective affinity toward SMCs and ECs suggest that EGCg-AuNPs may provide attractive alternatives to drug coated stents and therefore offer new therapeutic approaches in treating cardiovascular diseases. PMID:26938531

  2. The neglected nano-specific toxicity of ZnO nanoparticles in the yeast Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Zhang, Weicheng; Bao, Shaopan; Fang, Tao

    2016-04-01

    Nanoparticles (NPs) with unique physicochemical properties induce nano-specific (excess) toxicity in organisms compared with their bulk counterparts. Evaluation and consideration of nano-specific toxicity are meaningful for the safe design and environmental risk assessment of NPs. However, ZnO NPs have been reported to lack excess toxicity for diverse organisms. In the present study, the nano-specific toxicity of ZnO NPs was evaluated in the yeast Saccharomyces cerevisiae. Nano-specific toxicity of ZnO NPs was not observed in the wild type yeast. However, the ZnO NPs induced very similar nano-specific toxicities in the three mutants with comparable log Te (particle) values (0.64 vs 0.65 vs 0.62), suggesting that the mutants were more sensitive and specific for the NPs’ nano-specific toxicity. The toxic effects in the yeast were slightly attributable to dissolved zinc ions from the ZnO (nano or bulk) particles. Oxidative damage and mechanical damage contributed to the toxic effect of the ZnO particles. The mechanism of mechanical damage is proposed to be an inherent characteristic underlying the nano-specific toxicity in the mutants. The log Te (particle) was a useful parameter for evaluation of NPs nano-specific toxicity, whereas log Te (ion) efficiently determined the NPs toxicity associated with released ions.

  3. The neglected nano-specific toxicity of ZnO nanoparticles in the yeast Saccharomyces cerevisiae

    PubMed Central

    Zhang, Weicheng; Bao, Shaopan; Fang, Tao

    2016-01-01

    Nanoparticles (NPs) with unique physicochemical properties induce nano-specific (excess) toxicity in organisms compared with their bulk counterparts. Evaluation and consideration of nano-specific toxicity are meaningful for the safe design and environmental risk assessment of NPs. However, ZnO NPs have been reported to lack excess toxicity for diverse organisms. In the present study, the nano-specific toxicity of ZnO NPs was evaluated in the yeast Saccharomyces cerevisiae. Nano-specific toxicity of ZnO NPs was not observed in the wild type yeast. However, the ZnO NPs induced very similar nano-specific toxicities in the three mutants with comparable log Te (particle) values (0.64 vs 0.65 vs 0.62), suggesting that the mutants were more sensitive and specific for the NPs’ nano-specific toxicity. The toxic effects in the yeast were slightly attributable to dissolved zinc ions from the ZnO (nano or bulk) particles. Oxidative damage and mechanical damage contributed to the toxic effect of the ZnO particles. The mechanism of mechanical damage is proposed to be an inherent characteristic underlying the nano-specific toxicity in the mutants. The log Te (particle) was a useful parameter for evaluation of NPs nano-specific toxicity, whereas log Te (ion) efficiently determined the NPs toxicity associated with released ions. PMID:27094203

  4. Effects of reducing agents on the synthesis of Ag/rGO nanocomposites

    NASA Astrophysics Data System (ADS)

    Li, Yaya; Song, Qiong; Fan, Bingbing; Zhang, Rui

    2017-01-01

    A facile and rapid microwave-assisted green route has been used for the formation of Ag nanoparticles (AgNPs) and the reduction of graphene oxide (GO) simultaneously with five different reducing agents, sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium citrate, urea and ascorbic acid. The experimental results show that the structural properties and phase of Ag/reduced graphene oxide (Ag/rGO) nanocomposites are connected with reducing agent. AgNPs can be uniformly and compactly anchored on reduced GO (rGO) surface in the microwave field for 2 min by the assist of NaOH or KOH as reducing agent. The OH‑ can not only accelerate the ionization of acidic functional groups but also act as the nucleophile for Ag+. By addition of sodium citrate and urea, the GO sample remains its original structure, and Ag+ tends to form Ag2CO3, which then decomposes into Ag2O. While in the urea solution, Ag2O turns into [Ag(NH3)2]+ ions with abundant urea, then [Ag(NH3)2]+ ions are reduced to Ag0 by electrons, which leads to both Ag and Ag2O phase coexisting in the urea treated samples. In addition, it can be found that NaOH shows the best results in terms of the crystallinity and purity of Ag grains anchored on rGO surface.

  5. Cytotoxicity of ZnO NPs towards fresh water algae Scenedesmus obliquus at low exposure concentrations in UV-C, visible and dark conditions.

    PubMed

    Bhuvaneshwari, M; Iswarya, V; Archanaa, S; Madhu, G M; Kumar, G K Suraish; Nagarajan, R; Chandrasekaran, N; Mukherjee, Amitava

    2015-05-01

    Continuous increase in the usage of ZnO nanoparticles in commercial products has exacerbated the risk of release of these particles into the aquatic environment with possible harmful effects on the biota. In the current study, cytotoxic effects of two types of ZnO nanoparticles, having different initial effective diameters in filtered and sterilized lake water medium [487.5±2.55 nm for ZnO-1 NPs and 616.2±38.5 nm for ZnO-2 NPs] were evaluated towards a dominant freshwater algal isolate Scenedesmus obliquus in UV-C, visible and dark conditions at three exposure concentrations: 0.25, 0.5 and 1 mg/L. The toxic effects were found to be strongly dependent on the initial hydrodynamic particle size in the medium, the exposure concentrations and the irradiation conditions. The loss in viability, LDH release and ROS generation were significantly enhanced in the case of the smaller sized ZnO-1 NPs than in the case of ZnO-2 NPs under comparable test conditions. The toxicity of both types of ZnO NPs was considerably elevated under UV-C irradiation in comparison to that in dark and visible light conditions, the effects being more enhanced in case of ZnO-1 NPs. The size dependent dissolution of the ZnO NPs in the test medium and possible toxicity due to the released Zn(2+) ions was also noted. The surface adsorption of the nanoparticles was substantiated by scanning electron microscopy. The internalization/uptake of the NPs by the algal cells was confirmed by fluorescence microscopy, transmission electron microscopy, and elemental analyses.

  6. Memristive behavior of Al2O3 film with bottom electrode surface modified by Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Qin, Shu-Chao; Dong, Rui-Xin; Yan, Xun-Ling

    2014-09-01

    The memristive behavior of Al2O3-based device is significantly improved by introducing Ag nanoparticles (NPs). Inserting Ag NPs can effectively reduce the switching voltages, increase the resistance ratio (about 104) and enhance the sweep endurance (300 cycles). In particular, the stable switching properties are obtained by inserting an Ag NPs layer with an average diameter of 14 nm on the surface of bottom electrode, and the devices show a long retention time (more than 106 s) compared with the devices without Ag NPs. The switching mechanism is related to the oxygen-vacancy-based conducting filaments and the interfacial effect. The local enhancement and nonuniform distribution of electric field have the benefits to promote, induce and modulate the growth of conducting filaments, such as shape, location and orientation, which are responsible for the improvement performance of the devices.

  7. Memristive behavior of Al2O3 film with bottom electrode surface modified by Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Qin, Shu-Chao; Dong, Rui-Xin; Yan, Xun-Ling

    2015-02-01

    The memristive behavior of Al2O3-based device is significantly improved by introducing Ag nanoparticles (NPs). Inserting Ag NPs can effectively reduce the switching voltages, increase the resistance ratio (about 104) and enhance the sweep endurance (300 cycles). In particular, the stable switching properties are obtained by inserting an Ag NPs layer with an average diameter of 14 nm on the surface of bottom electrode, and the devices show a long retention time (more than 106 s) compared with the devices without Ag NPs. The switching mechanism is related to the oxygen-vacancy-based conducting filaments and the interfacial effect. The local enhancement and nonuniform distribution of electric field have the benefits to promote, induce and modulate the growth of conducting filaments, such as shape, location and orientation, which are responsible for the improvement performance of the devices.

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

    NASA Astrophysics Data System (ADS)

    Liu, Min; Zhang, De-Xiang; Chen, Shumei; Wen, Tian

    2016-05-01

    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).

  9. In vivo biodistribution and synergistic toxicity of silica nanoparticles and cadmium chloride in mice.

    PubMed

    Guo, Mingchun; Xu, Xiaolong; Yan, Xincheng; Wang, Shasha; Gao, Shang; Zhu, Shanshan

    2013-09-15

    Silica nanoparticles (SiNPs) are now in daily use due to their low intrinsic toxicity. Cadmium is a ubiquitous environmental pollutant. In spite of real risk of humans' co-exposure to SiNPs and cadmium, their synergistic toxicity is still unclear. Here, we report the synergistic effects of SiNPs and CdCl₂ on their biodistribution and subacute toxicity in mice. The biodistributions, histopathological changes, serum biochemical parameters and oxidative stress responses were determined after intraperitoneal injection of SiNPs and/or CdCl₂ to mice. SiNPs and CdCl₂ have a positive synergistic toxicity in mice. Although SiNPs were low toxic to mice, co-exposure of SiNPs and CdCl₂ significantly enhanced CdCl₂-induced oxidative damage in the liver as indicated by the severe liver dysfunction and histopathological abnormalities. Co-exposure to SiNPs and CdCl₂ markedly increased the cadmium accumulation in the liver, which induced significant hepatic oxidative stress. In vitro binding assays indicated that serum albumin and Cd(2+) mutually enhanced the binding of each other to SiNPs via the interaction of serum albumin and Cd(2+). The uptake of serum albumin- and Cd(2+)-bound SiNPs by the macrophages significantly increased cadmium accumulation in mice. These results demonstrate that serum albumins play an important role in the positive synergistic toxicity of SiNPs and CdCl₂.

  10. Two-step synthesis of Ag@GQD hybrid with enhanced photothermal effect and catalytic performance

    NASA Astrophysics Data System (ADS)

    Wu, Cong; Yuan, Yali; He, Qian; Song, Rui

    2016-12-01

    A novel Ag@GQD (graphene quantum dot) hybrid fabricated by a facile two-step strategy is presented: the GQDs are prepared by citrate acid and AgNO3 is reduced. Catalytic studies showed that the Ag@GQD hybrid exhibited excellent photothermal effect and catalytic performance for 4-nitrophenol (4-NP) reduction, suggesting that the GQDs enhanced the catalytic activity via a synergistic effect and the Ag NPs boosted the catalytic efficiency through SPR-mediated photothermal local heating.

  11. 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.

  12. Determining the Concentration Dependent Transformations of Ag Nanoparticles in Complex Media: Using SP-ICP-MS and Au@Ag Core-Shell Nanoparticles as Tracers.

    PubMed

    Merrifield, Ruth C; Stephan, Chady; Lead, Jamie

    2017-03-01

    The fate, behavior, and impact of engineered nanoparticles (NPs) in toxicological and environmental media are driven by complex processes which are difficult to quantify. A key limitation is the ability to perform measurements at low and environmentally relevant concentrations, since concentration may be a key factor determining fate and effects. Here, we use single particle inductively coupled mass spectroscopy (SP-ICP-MS) to measure directly NP diameter and particle number concentration of suspensions containing gold-silver core-shell (Au@Ag) NPs in EPA moderately hard water (MHW) and MHW containing 2.5 mg L(-1) Suwannee River fulvic acid. The Au core of the Au@Ag NPs acts as an internal standard, and aids in the analysis of the complex Ag transformations. The high sensitivity of SP-ICP-MS, along with the Au@Ag NPs, enabled us to track the NP transformations in the range 0.01 and 50 μg L(-1), without further sample preparation. On the basis of the analysis of both Au and Ag parameters (size, size distribution, and particle number), concentration was shown to be a key factor in NP behavior. At higher concentration, NPs were in an aggregation-dominated regime, while at the lower and environmentally representative concentrations, dissolution of Ag was dominant and aggregation was negligible. In addition, further formation of ionic silver as Ag NPs in the form of AgS or AgCl was shown to occur. Between 1 and 10 μg L(-1), both aggregation and dissolution were important. The results suggest that, under realistic conditions, the role of NP homoaggregation may be minimal. In addition, the complexity of exposure and dose in dose-response relationships is highlighted.

  13. Preparation of AgBr@SiO2 core@shell hybrid nanoparticles and their bactericidal activity.

    PubMed

    Li, Yuanyuan; Yang, Lisu; Zhao, Yanbao; Li, Binjie; Sun, Lei; Luo, Huajuan

    2013-04-01

    AgBr@SiO2 core@shell hybrid nanoparticles (NPs) were successfully prepared by sol-gel method. Their morphology and structure were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The hybrid NPs are predominantly spherical in shape, with an average diameter of 180-200 nm, and each NP contains one inorganic core. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the hybrid NPs were examined against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), respectively. Results indicated that the AgBr@SiO2 NPs had excellent antibacterial activity.

  14. Screening sensitive nanosensors via the investigation of shape-dependent localized surface plasmon resonance of single Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Yue; Huang, Cheng Zhi

    2013-07-01

    Understanding the localized surface plasmon resonance (LSPR) of differently shaped plasmonic nanoparticles benefits screening and designing highly sensitive single nanoparticle sensors. Herein, in the present work, we systematically investigated the shape-dependent scattering light colours and refractive index (RI) sensitivity of Ag nanoparticles (AgNPs) at the single nanoparticle level using conventional dark-field light scattering microscopy and spectroscopy. AgNPs in various shapes and scattering colourful light were synthesized, and the shape effect on the scattering light colour was determined by the colocalization of the same nanoparticles with dark-field microscopy (DFM) and scanning electron microscopy (SEM). The results showed that the AgNPs that scattered blue, cyan, yellow, and red light are spheres, cubes, triangular bipyramids, and rods, respectively, which enable us to directly recognize the shape of AgNPs through dark-field microscopy instead of electron microscopy. Further studies on investigation of the scattering spectral responses of single AgNPs to their surrounding solvents show that the RI sensitivity of AgNPs of different shapes followed the order of rods > cubes > triangular bipyramids > spheres. Among the commonly studied AgNPs, Ag nanorods have the highest RI sensitivity, which increases as the aspect ratio increases. Then, AgNPs of various shapes were used as single nanoparticle sensors for probing the adsorption of small molecules.Understanding the localized surface plasmon resonance (LSPR) of differently shaped plasmonic nanoparticles benefits screening and designing highly sensitive single nanoparticle sensors. Herein, in the present work, we systematically investigated the shape-dependent scattering light colours and refractive index (RI) sensitivity of Ag nanoparticles (AgNPs) at the single nanoparticle level using conventional dark-field light scattering microscopy and spectroscopy. AgNPs in various shapes and scattering colourful

  15. Where does the toxicity of metal oxide nanoparticles come from: The nanoparticles, the ions, or a combination of both?

    PubMed

    Wang, Dali; Lin, Zhifen; Wang, Ting; Yao, Zhifeng; Qin, Mengnan; Zheng, Shourong; Lu, Wei

    2016-05-05

    The toxicity of metal oxide nanoparticles (NPs) has aroused great concern over the past few years. However, there still remains the question whether the toxicity of the metal oxide NPs originates from the released ions or the NPs themselves. In this study, the metal ion release of CuO, Fe2O3, ZnO, Co3O4, Cr2O3, and NiO NPs in aqueous media was investigated, and their contributions to the metal oxide NPs' inhibition on the bioluminescence of Photobacterium phosphoreum were studied. It was found that the ions release of the metal oxide NPs in aqueous media was complex, depending on both the dissolution and adsorption processes of the metal oxide NPs. The relationships between the metal oxide NPs' antibacterial effects and their released metal ions could be divided into three categories: (1) the ZnO NPs' antibacterial effect was due solely to the released Zn(2+); (2) the CuO NPs' antibacterial effect originated from both the released Cu(2+),and the CuO particles; and (3) the antibacterial effects of Fe2O3, Co3O4, Cr2O3, and NiO NPs were caused by the NPs themselves. Our findings suggest that the ions release and their contributions to the NPs' toxicity should be considered in the toxicity evaluations of the metal oxide NPs.

  16. A simple preparation of Ag@graphene nanocomposites for surface-enhanced Raman spectroscopy of fluorescent anticancer drug

    NASA Astrophysics Data System (ADS)

    Meng, Ying; Yan, Xueying; Wang, Yi

    2016-05-01

    A simple method was developed to synthesize Ag@graphene nanocomposites with rough Ag nanoparticles (AgNPs) conjugated with graphene nanosheets, and the nanocomposites could be used as substrates for effective surface-enhanced Raman spectroscopy (SERS) of fluorescent anticancer drug (Dox) since they could not only enhance the Raman signals but also suppress the fluorescent signals.

  17. Developmental toxicity of engineered nanomaterials in rodents.

    PubMed

    Ema, Makoto; Gamo, Masashi; Honda, Kazumasa

    2016-05-15

    We summarized significant effects reported in the literature on the developmental toxicity of engineered nanomaterials (ENMs) in rodents. The developmental toxicity of ENMs included not only structural abnormalities, but also death, growth retardation, and behavioral and functional abnormalities. Most studies were performed on mice using an injection route of exposure. Teratogenic effects were indicated when multi-walled carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), and TiO2-nanoparticles were administered to mice during early gestation. Reactive oxygen species levels were increased in placentas and malformed fetuses and their placentas after prenatal exposure to MWCNTs and SWCNTs, respectively. The pre- and postnatal mortalities and growth retardation in offspring increased after prenatal exposure to ENMs. Histopathological and functional abnormalities were also induced in placentas after prenatal exposure to ENMs. Maternal exposure to ENMs induced behavioral alterations, histopathological and biochemical changes in the central nervous system, increased susceptibility to allergy, transplacental genotoxicity, and vascular, immunological, and reproductive effects in offspring. The size- and developmental stage-dependent placental transfer of ENMs was noted after maternal exposure. Silver accumulated in the visceral yolk sac after being injected with Ag-NPs during early gestation. Although currently available data has provided initial information on the potential developmental toxicity of ENMs, that on the developmental toxicity of ENMs is still very limited. Further studies using well-characterized ENMs, state-of the-art study protocols, and appropriate routes of exposure are required in order to clarify these developmental effects and provide information suitable for risk assessments of ENMs.

  18. The Catalytic Behaviour of NanoAg@montmorillonite Composite Materials

    NASA Astrophysics Data System (ADS)

    Karlíková, Martina; Kvítek, Libor; Prucek, Robert; Panáček, Aleš; Filip, Jan; Pechoušek, Jiří; Adegboyega, Nathaniel F.

    The preparation of nanoAg@montmorillonite composite materials and their catalytic activity is reported in this article. The nanoAg@montmorillonite composite materials were prepared by the adsorption of silver NPs, with an average size about 30 nm, from their aqueous dispersion onto two types of montmorillonite with different chemical composition. Silver NPs were prepared via modified Tollens process, which involves the reduction of [Ag(NH3)2]+ complex cation by maltose. The amount of silver NPs anchored onto the MMT surfaces was determined by UV-VIS spectroscopy; the decrease in absorbance of the dispersion after the adsorption was monitored. Prepared nanocomposite materials were subsequently characterized by means of transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The reduction of 4-nitrophenol by sodium borohydride was chosen to examine the catalytic properties of the synthesized silver nanocomposite materials.

  19. A study on Cu and Ag doped ZnO nanoparticles for the photocatalytic degradation of brilliant green dye: synthesis and characterization.

    PubMed

    Gnanaprakasam, A; Sivakumar, V M; Thirumarimurugan, M

    2016-09-01

    Novel polyvinyl pyrrolidone capped pure, Ag (1-3%) and Cu doped (1-3%) zinc oxide (ZnO) nanoparticles (NPs) were successfully synthesized via the co-precipitation method. The synthesized NPs were characterized by UV-visible spectrophotometry, X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and field emission scanning electron microscopy (FE-SEM). Compared to pure ZnO, the absorption bands of Ag and Cu doped ZnO NPs were shifted and, further, the band gap energy was also decreased which confirms the incorporation of Ag and Cu into the ZnO lattice. The XRD diffraction peak confirms that all the synthesized compounds are found to be of highly crystalline hexagonal wurtzite structure. In addition, the presence of Ag and Cu in the ZnO NPs was further evidenced from EDS analysis. FE-SEM images established the morphology of the doped ZnO NPs which was not affected by the addition of Ag and Cu. The photocatalytic activity of undoped, Ag doped (1-3%) and Cu doped (1-3%) ZnO NPs were tested with brilliant green dye under UV irradiation. Degradation study reveals that doping has a distinct effect on the photocatalytic behavior of ZnO NPs. In addition to that, kinetic, thermodynamic and reusability studies have been performed for the 2% Ag doped ZnO NPs.

  20. USGS-NPS Servicewide Benthic Mapping Program (SBMP) workshop report

    USGS Publications Warehouse

    Moses, Christopher S.; Nayagandhi, Amar; Brock, John; Beavers, Rebecca

    2010-01-01

    The National Park Service (NPS) Inventory and Monitoring (I&M) Program recently allocated funds to initiate a benthic mapping program in ocean and Great Lakes parks in alignment with the NPS Ocean Park Stewardship 2007-2008 Action Plan. Seventy-four (ocean and Great Lakes) parks, spanning more than 5,000 miles of coastline, many affected by increasing coastal storms and other natural and anthropogenic processes, make the development of a Servicewide Benthic Mapping Program (SBMP) timely. The resulting maps and associated reports will be provided to NPS managers in a consistent servicewide format to help park managers protect and manage the 3 million acres of submerged National Park System natural and cultural resources. Of the 74 ocean and Great Lakes park units, the 40 parks with submerged acreage will be the focus in the early years of the SBMP. The NPS and U.S. Geological Survey (USGS) convened a workshop (June 3-5, 2008) in Lakewood, CO. The assembly of experts from the NPS and other Federal and non-Federal agencies clarified the needs and goals of the NPS SBMP and was one of the key first steps in designing the benthic mapping program. The central needs for individual parks, park networks, and regions identified by workshop participants were maps including bathymetry, bottom type, geology, and biology. This workshop, although not an exhaustive survey of data-acquisition technologies, highlighted the more promising technologies being used, existing sources of data, and the need for partnerships to leverage resources. Workshop products include recommended classification schemes and management approaches for consistent application and products similar to other long-term NPS benthic mapping efforts. As part of the SBMP, recommendations from this workshop, including application of an improved version of the Coastal and Marine Ecological Classification Standard (CMECS), will be tested in several pilot parks. In 2008, in conjunction with the findings of this workshop

  1. Evaluating the toxicity of selected types of nanochemicals.

    PubMed

    Kumar, Vineet; Kumari, Avnesh; Guleria, Praveen; Yadav, Sudesh Kumar

    2012-01-01

    Nanotechnology is a fast growing field that provides for the development of materials that have new dimensions, novel properties, and a broader array of applications. Various scientific groups are keen about this technology and are devoting themselves to the development of more, new, and better nanomaterials. In the near future, expectations are that no field will be left untouched by the magical benefits available through application of nanotechnology. Presently, there is only limited knowledge concerning the toxicological effects of NPs. However, it is now known that the toxic behavior of NPs differ from their bulk counterparts. Even NPs that have the same chemical composition differ in their toxicological properties; the differences in toxicity depend upon size, shape, and surface covering. Hence, before NPs are commercially used it is most important that they be subjected to appropriate toxicity evaluation. Among the parameters of NPs that must be evaluated for their effect on toxicity are surface charges, types of coating material, and reactivity of NPs. In this article, we have reviewed the literature pertinent to the toxicity of metal oxide NPs, metallic NPs, quantum dots (QDs), silica (SiO2) NPs, carbon nanotubes (CNTs), and certain other carbon nanomaterials (NMs). These NPs have already found a wide range of applications around the world. In vitro and in vivo studies on NPs have revealed that most are toxic to animals. However, their toxic behavior varies with their size, shape, surface charge, type of coating material and reactivity. Dose, route of administration, and exposure are critical factors that affect the degree of toxicity produced by any particular type of NP. It is for this reason that we believe a careful and rigorous toxicity testing is necessary before any NP is declared to be safe for broad use. We also believe that an agreed upon testing system is needed that can be used to suitably, accurately, and economically assess the toxicity of NPs

  2. Encapsulated Fluorescent Ag NPs as Novel Indicators for High-Energy Ionizing Radiation

    DTIC Science & Technology

    2014-06-01

    angstrom atmosphere (normal) bar barn British thermal unit (thermochemical) calorie (thermochemical) cal (thermochemical/cm 2 ) curie degree...which yielded levels near zero (the background spectra were subtracted). However, for the 50 Gy dosage the 16 hr equilibration time was optimal, leading

  3. Gamma radiation synthesis of colloidal AgNPs for its potential application in antimicrobial fabrics

    NASA Astrophysics Data System (ADS)

    Bera, Anuradha; Garai, Purabi; Singh, Rita; Prakash Gupta, P.; Malav, Shatrughan; Singh, Durgeshwer; Kumar, Devendra; Tiwari, B. L.; Vaijapurkar, S. G.

    2015-10-01

    Highly stable colloidal solution of silver nanoparticles in a water-isopropanol-polyvinyl alcohol system was prepared through 60Co-gamma radiation at total dose of 35 kGy at dose rate of 5.67 kGy/h under nitrogen atmosphere. Ultraviolet-visible (UV-vis), X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) of the obtained colloidal solution indicated the formation of spherical shaped well mono dispersed silver nanoparticles with average diameter about 30 nm having very narrow size distribution. The radiolytically obtained nanosilver colloid was coated onto cotton fabrics by a simple industrial screen printing method and its adhesion with the fabric was found out by leaching studies using Atomic Absorption Spectrophotometry (AAS). Good adhesion was achieved by the adopted method wherein 89.5% of the coated nanosilver was retained in the fabric even after keeping the fabrics soaked in water for more than 60 h. Antimicrobial efficacy tests of the nanosilver coated cotton fabric showed that nanosilver coating is effective in killing both bacterial and fungal strains even at very low nanosilver loading (21.81 μgm/cm2). Nanosilver coating on the cotton fabric did not allow microbes (Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and Candida albicans) to adhere and proliferate on fabric surface. Staphylococci (Staphylococcus aureus) and Yeast (Candida albicans) showed inhibition zones in presence of these nanosilver coated fabrics while no inhibition zone was observed with the uncoated control fabric.

  4. Kraft lignin/silica-AgNPs as a functional material with antibacterial activity.

    PubMed

    Klapiszewski, Łukasz; Rzemieniecki, Tomasz; Krawczyk, Magdalena; Malina, Dagmara; Norman, Małgorzata; Zdarta, Jakub; Majchrzak, Izabela; Dobrowolska, Anna; Czaczyk, Katarzyna; Jesionowski, Teofil

    2015-10-01

    Advanced functional silica/lignin hybrid materials, modified with nanosilver, were obtained. The commercial silica Syloid 244 was used, modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane to increase its chemical affinity to lignin. Similarly, kraft lignin was oxidized using a solution of sodium periodate to activate appropriate functional groups on its surface. Silver nanoparticles were grafted onto the resulting silica/lignin hybrids. The systems obtained were comprehensively tested using available techniques and methods, including transmission electron microscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, elemental analysis and atomic absorption spectroscopy. An evaluation was also made of the electrokinetic stability of the systems with and without silver nanoparticles. Conclusions were drawn concerning the chemical nature of the bonds between the precursors and the effectiveness of the method of binding nanosilver to the hybrid materials. The antimicrobial activity of the studied materials was tested against five species of Gram-positive and Gram-negative bacteria. The addition of silver nanoparticles to the silica/lignin hybrids led to inhibition of the growth of the analyzed bacteria. The best results were obtained against Pseudomonas aeruginosa, a dangerous human pathogen.

  5. Surfactants present complex joint effects on the toxicities of metal oxide nanoparticles.

    PubMed

    Wang, Dali; Lin, Zhifen; Yao, Zhifeng; Yu, Hongxia

    2014-08-01

    The potential toxicities of nanoparticles (NPs) have been intensively discussed over the past decade. In addition to their single toxicities, NPs can interact with other environmental chemicals and thereby exert joint effects on biological systems and the environment. The present study investigated the combined toxicities of NPs and surfactants, which are among the chemicals that most likely coexist with NPs. Photobacterium phosphoreum was employed as the model organism. The results indicate that surfactants with different ion types can alter the properties of NPs (i.e., particle size and surface charge) in different ways and present complex joint effects on NP toxicities. Mixtures of different NPs and surfactants exhibited antagonistic, synergistic, and additive effects. In particular, the toxicity of ZnO was observed to result from its dissolved Zn(2+); thus, the joint effects of the ZnO NPs and surfactants can be explained by the interactions between the Zn ions and the surfactants. Our study suggests that the potential hazards caused by mixtures of NPs and surfactants are different from those caused by single NPs. Because surfactants are extensively used in the field of nanotechnology and are likely to coexist with NPs in natural waters, the ecological risk assessments of NPs should consider the impacts of surfactants.

  6. Plasmon coupling-enhanced two-photon photoluminescence of Au@Ag core-shell nanoparticles and applications in the nuclease assay

    NASA Astrophysics Data System (ADS)

    Yuan, Peiyan; Ma, Rizhao; Gao, Nengyue; Garai, Monalisa; Xu, Qing-Hua

    2015-05-01

    Au and Ag nanoparticles (NPs) have been known to display significantly enhanced two-photon photoluminescence (2PPL) upon the formation of nanoparticle aggregates. The enhancement effect of the core-shell nanoparticles has not been explored so far. Here we have prepared Au@Ag bimetallic core-shell nanoparticles with different thicknesses (1.1, 2.1, 3.5, 4.5, and 5.5 nm) of silver coating on 19 nm Au NPs to investigate the composition effects on plasmon coupling-enhanced 2PPL. A maximum 2PPL enhancement factor (IcoupledNPs/IisolatedNPs) of up to 840-fold was obtained for Au@Ag NPs with ~3.5 nm Ag nanoshells. These Au@Ag NPs were subsequently utilized in two-photon detection of S1 nuclease as a photoluminescence turn on probe. This method displayed high sensitivity with the limit of detection of 1.4 × 10-6 U μL-1 and an excellent selectivity.Au and Ag nanoparticles (NPs) have been known to display significantly enhanced two-photon photoluminescence (2PPL) upon the formation of nanoparticle aggregates. The enhancement effect of the core-shell nanoparticles has not been explored so far. Here we have prepared Au@Ag bimetallic core-shell nanoparticles with different thicknesses (1.1, 2.1, 3.5, 4.5, and 5.5 nm) of silver coating on 19 nm Au NPs to investigate the composition effects on plasmon coupling-enhanced 2PPL. A maximum 2PPL enhancement factor (IcoupledNPs/IisolatedNPs) of up to 840-fold was obtained for Au@Ag NPs with ~3.5 nm Ag nanoshells. These Au@Ag NPs were subsequently utilized in two-photon detection of S1 nuclease as a photoluminescence turn on probe. This method displayed high sensitivity with the limit of detection of 1.4 × 10-6 U μL-1 and an excellent selectivity. Electronic supplementary information (ESI) available: TEM images, histograms of the sizes of Au@Ag NPs; extinction, 2PPL spectra of aggregated NPs, cysteamine, ssDNA and S1 nuclease; 2-photon action cross section of aggregated NPs; lengths of ssDNA and [NaCl] effect; excitation power

  7. Ultrafine Au and Ag Nanoparticles Synthesized from Self-Assembled Peptide Fibers and Their Excellent Catalytic Activity.

    PubMed

    Xu, Wenlong; Hong, Yue; Hu, Yuanyuan; Hao, Jingcheng; Song, Aixin

    2016-07-18

    The self-assembly of an amphiphilic peptide molecule to form nanofibers facilitated by Ag(+) ions was investigated. Ultrafine AgNPs (NPs=nanoparticles) with an average size of 1.67 nm were synthesized in situ along the fibers due to the weak reducibility of the -SH group on the peptide molecule. By adding NaBH4 to the peptide solution, ultrafine AgNPs and AuNPs were synthesized with an average size of 1.35 and 1.18 nm, respectively. The AuNPs, AgNPs, and AgNPs/nanofibers all exhibited excellent catalytic activity toward the reduction of 4-nitrophenol, with turnover frequency (TOF) values of 720, 188, and 96 h(-1) , respectively. Three dyes were selected for catalytic degradation by the prepared nanoparticles and the nanoparticles showed selective catalysis activity toward the different dyes. It was a surprising discovery that the ultrafine AuNPs in this work had an extremely high catalytic activity toward methylene blue, with a reaction rate constant of 0.21 s(-1) and a TOF value of 1899 h(-1) .

  8. Strong interactions with polyethylenimine-coated human serum albumin nanoparticles (PEI-HSA NPs) alter α-synuclein conformation and aggregation kinetics

    NASA Astrophysics Data System (ADS)

    Mohammad-Beigi, Hossein; Shojaosadati, Seyed Abbas; Marvian, Amir Tayaranian; Pedersen, Jannik Nedergaard; Klausen, Lasse Hyldgaard; Christiansen, Gunna; Pedersen, Jan Skov; Dong, Mingdong; Morshedi, Dina; Otzen, Daniel E.

    2015-11-01

    The interaction between nanoparticles (NPs) and the small intrinsically disordered protein α-synuclein (αSN), whose aggregation is central in the development of Parkinson's disease, is of great relevance in biomedical applications of NPs as drug carriers. Here we showed using a combination of different techniques that αSN interacts strongly with positively charged polyethylenimine-coated human serum albumin (PEI-HSA) NPs, leading to a significant alteration in the αSN secondary structure. In contrast, the weak interactions of αSN with HSA NPs allowed αSN to remain unfolded. These different levels of interactions had different effects on αSN aggregation. While the weakly interacting HSA NPs did not alter the aggregation kinetic parameters of αSN, the rate of primary nucleation increased in the presence of PEI-HSA NPs. The aggregation rate changed in a PEI-HSA NP-concentration dependent and size independent manner and led to fibrils which were covered with small aggregates. Furthermore, PEI-HSA NPs reduced the level of membrane-perturbing oligomers and reduced oligomer toxicity in cell assays, highlighting a potential role for NPs in reducing αSN pathogenicity in vivo. Collectively, our results highlight the fact that a simple modification of NPs can strongly modulate interactions with target proteins, which may have important and positive implications in NP safety.The interaction between nanoparticles (NPs) and the small intrinsically disordered protein α-synuclein (αSN), whose aggregation is central in the development of Parkinson's disease, is of great relevance in biomedical applications of NPs as drug carriers. Here we showed using a combination of different techniques that αSN interacts strongly with positively charged polyethylenimine-coated human serum albumin (PEI-HSA) NPs, leading to a significant alteration in the αSN secondary structure. In contrast, the weak interactions of αSN with HSA NPs allowed αSN to remain unfolded. These different

  9. Revamped NPS Brings More Focus to CTE Issues

    ERIC Educational Resources Information Center

    Techniques: Connecting Education and Careers (J3), 2008

    2008-01-01

    In March, attendees at the annual ACTE National Policy Seminar (NPS) got more than they bargained for. With a new hotel and a completely reorganized agenda, career and technical educators were more than energized to bring the career and technical education (CTE) message to Capitol Hill. This year marked the first time ACTE held a special briefing…

  10. 252. Mabry Mill. View of the mill and the NPS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    252. Mabry Mill. View of the mill and the NPS dredged reflecting pond which illustrates how the parkway has manipulated the landscape to make it more picturesque. Looking north-northwest from interpretative trail. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  11. Complete Genome Sequence of Streptococcus sp. Strain NPS 308

    PubMed Central

    Ogura, Yoshitoshi; Sato, Keiko; Imamura, Keigo; Hoshino, Tomonori; Nishiguchi, Miyuki; Hasuwa, Tomoyuki; Moriuchi, Hiroyuki; Hayashi, Tetsuya; Fujiwara, Taku

    2016-01-01

    Streptococcus sp. strain NPS 308, isolated from an 8-year-old girl diagnosed with infective endocarditis, likely presents a novel species of Streptococcus. Here, we present a complete genome sequence of this species, which will contribute to better understanding of the pathogenesis of infective endocarditis. PMID:28007849

  12. Synthesis, characterization and multifunctional properties of plasmonic Ag-TiO2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Prakash, Jai; Kumar, Promod; Harris, R. A.; Swart, Chantel; Neethling, J. H.; Janse van Vuuren, A.; Swart, H. C.

    2016-09-01

    We report on the synthesis of multifunctional Ag-TiO2 nanocomposites and their optical, physio-chemical, surface enhanced Raman scattering (SERS) and antibacterial properties. A series of Ag-TiO2 nanocomposites were synthesized by sol-gel technique and characterized by x-ray diffraction, scanning and transmission electron microscopy, energy-dispersed x-ray analysis, photoluminescence, UV-vis, x-ray photoelectron and Raman spectroscopy and Brunauer-Emmett-Teller method. The Ag nanoparticles (NPs) (7-20 nm) were found to be uniformly distributed around and strongly attached to TiO2 NPs. The novel optical responses of the nanocomposites are due to the strong electric field from the localized surface plasmon (LSP) excitation of the Ag NPs and decreased recombination of photo-induced electrons and holes at Ag-TiO2 interface providing potential materials for photocatalysis. The nanocomposites show enhancement in the SERS signals of methyl orange (MO) molecules with increasing Ag content attributed to the long-range electromagnetic enhancement from the excited LSP of the Ag NPs. To further understand the SERS activity, molecular mechanics and molecular dynamics simulations were used to study the geometries and SERS enhancement of MO adsorbed onto Ag-TiO2 respectively. Simulation results indicate that number of ligands (MO) that adsorb onto the Ag NPs as well as binding energy per ligand increases with increasing NP density and molecule-to-surface orientation is mainly flat resulting in strong bond strength between MO and Ag NP surface and enhanced SERS signals. The antimicrobial activity of the Ag-TiO2 nanocomposites was tested against the bacterium Staphylococcus aureus and enhanced antibacterial effect was observed with increasing Ag content explained by contact killing action mechanism. These results foresee promising applications of the plasmonic metal-semiconductor based nano-biocomposites for both chemical and biological samples.

  13. Toxicity of nanomaterials

    PubMed Central

    Sharifi, Shahriar; Behzadi, Shahed; Laurent, Sophie; Forrest, M. Laird; Stroeve, Pieter

    2015-01-01

    Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan’s Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product’s life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity. PMID:22170510

  14. Morphology Effect of Ni-Ag/CARBON Nanomaterials on Their Electrocatalytic Activity for Glucose Oxidation

    NASA Astrophysics Data System (ADS)

    Ouyang, Ruizhuo; Li, Weiwei; Yang, Yang; Zhang, Wangyao; Feng, Kai; Zong, Tianyu; An, Yarui; Zhou, Shuang; Miao, Yuqing

    2016-06-01

    We presented here three carbon-nanomaterials-based modified glassy carbon electrodes (GCE) with Ni-Ag nanohybrid nanoparticles (NPs) deposited upon, including single-wall carbon nanotubes (SWCNTs), multi-wall carbon nanotubes (MWCNTs) and the mesoporous carbons (MPCs), and compared their morphology effects on both Ni-Ag deposition quality and electrocatalytic performances toward Glu oxidation. After being deposited with Ni-Ag NPs, a homogenous surface with very small Ni-Ag NPs was obtained for Ni-Ag/SWCNTs/GCE, while heterogeneous, coarse surfaces with obvious embedment with large Ni-Ag particles were observed for both Ni-Ag/MWCNTs/GCE and Ni-Ag/MPC/GCE. All three modified electrodes were well characterized in terms of surface morphology, electron transfer rate, hydrophilicity, interference resistance, stability, electrocatalytic behaviors as well as practicability in real samples, based on which Ni-Ag/SWCNTs/GCE was always proved to be more advantageous over other two composite electrodes. Such advantage of Ni-Ag/SWCNTs/GCE was attributed to its desirable surface morphology good for Ni-Ag deposition and exposure of as many active sites as possible to Glu oxidation, leading to the extraordinary electrocatalytic performance.

  15. Evaluation of environmental safety concentrations of DMSA Coated Fe2O3-NPs using different assay systems in nematode Caenorhabditis elegans.

    PubMed

    Wu, Qiuli; Li, Yiping; Tang, Meng; Wang, Dayong

    2012-01-01

    Dimercaptosuccinic acid (DMSA) coating improves the uptake efficiency presumably by engendering the Fe(2)O(3)-NPs. In the present study, we investigated the possible environmental safety concentrations of Fe(2)O(3)-NPs using different assay systems in nematode Caenorhabditis elegans with lethality, development, reproduction, locomotion behavior, pharyngeal pumping, defecation, intestinal autofluorescence and reactive oxygen species (ROS) production as the endpoints. After exposure from L4-larvae for 24-hr, DMSA coated Fe(2)O(3)-NPs at concentrations more than 50 mg/L exhibited adverse effects on nematodes. After exposure from L1-larvae to adult, DMSA coated Fe(2)O(3)-NPs at concentrations more than 500 μg/L had adverse effects on nematodes. After exposure from L1-larvae to day-8 adult, DMSA coated Fe(2)O(3)-NPs at concentrations more than 100 μg/L resulted in the adverse effects on nematodes. Accompanied with the alterations of locomotion behaviors, ROS production was pronouncedly induced by exposure to DMSA coated Fe(2)O(3)-NPs in the examined three assay systems, and the close associations of ROS production with lethality, growth, reproduction, locomotion behavior, pharyngeal pumping, defecation, or intestinal autofluorescence in nematodes exposed to DMSA coated Fe(2)O(3)-NPs were confirmed by the linear regression analysis. Moreover, mutations of sod-2 and sod-3 genes, encoding Mn-SODs, showed more susceptible properties than wild-type when they were used for assessing the DMSA coated Fe(2)O(3)-NPs-induced toxicity, and the safety concentrations for DMSA coated Fe(2)O(3)-NPs should be defined as concentrations lower than 10 μg/L in sod-2 and sod-3 mutant nematodes.

  16. Total synthesis of isotopically enriched Si-29 silica NPs as potential spikes for isotope dilution quantification of natural silica NPs.

    PubMed

    Pálmai, Marcell; Szalay, Roland; Bartczak, Dorota; Varga, Zoltán; Nagy, Lívia Naszályi; Gollwitzer, Christian; Krumrey, Michael; Goenaga-Infante, Heidi

    2015-05-01

    A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29 silica nanoparticles ((29)Si-silica NPs) with the purpose of using them as spikes for isotope dilution mass spectrometry (IDMS) quantification of silica NPs with natural isotopic distribution. Si-29 tetraethyl orthosilicate ((29)Si-TEOS), the silica precursor was prepared in two steps starting from elementary silicon-29 pellets. In the first step Si-29 silicon tetrachloride ((29)SiCl4) was prepared by heating elementary silicon-29 in chlorine gas stream. By using a multistep cooling system and the dilution of the volatile and moisture-sensitive (29)SiCl4 in carbon tetrachloride as inert medium we managed to reduce product loss caused by evaporation. (29)Si-TEOS was obtained by treating (29)SiCl4 with absolute ethanol. Structural characterisation of (29)Si-TEOS was performed by using (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. For the NP preparation, a basic amino acid catalysis route was used and the resulting NPs were analysed using transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential measurements. Finally, the feasibility of using enriched NPs for on-line field-flow fractionation coupled with multi-angle light scattering and inductively coupled plasma mass spectrometry (FFF/MALS/ICP-MS) has been demonstrated.

  17. Toxicity of silver and titanium dioxide nanoparticle suspensions to the aquatic invertebrate, Daphnia magna.

    PubMed

    Das, Pranab; Xenopoulos, Marguerite A; Metcalfe, Chris D

    2013-07-01

    The purpose of this study was to investigate the 48 h acute toxicity of capped silver nanoparticles (AgNPs), and capped and uncapped titanium dioxide (nTiO₂) to Daphnia magna neonates. In addition, a 24 days chronic toxicity study was performed for D. magna exposed to uncapped nTiO₂ to evaluate effects on growth, reproduction and survival. The 48 h median lethal concentrations (LC₅₀) for carboxy-functionalized capped AgNPs and uncapped nTiO₂ were 2.75 μg/L and 7.75 mg/L, respectively. In contrast, no mortalities were observed for Daphnia exposed to carboxy-functionalized capped nTiO₂ at concentrations up to 30 mg/L. In the chronic toxicity experiment with uncapped nTiO₂, the growth, reproduction and survival of D. magna were significantly (p < 0.05) reduced at concentrations ranging from 4.5 to 7.5 mg/L. Growth and reproduction were reduced by 35 % and 93 %, respectively in the treatments at the highest uncapped nTiO₂ concentration (7.5 mg/L). Time to first reproduction was delayed by 2-3 days in D. magna and the test organisms produced only 1-2 broods over 24 days exposure to the highest concentration of uncapped nTiO₂. Overall, the results from the present study indicate that exposures of aquatic invertebrates to nanoparticles could have important ecological effects on lower trophic levels in aquatic ecosystems.

  18. Selective photochemical synthesis of Ag nanoparticles on position-controlled ZnO nanorods for the enhancement of yellow-green light emission.

    PubMed

    Park, Hyeong-Ho; Zhang, Xin; Lee, Keun Woo; Sohn, Ahrum; Kim, Dong-Wook; Kim, Joondong; Song, Jin-Won; Choi, Young Su; Lee, Hee Kwan; Jung, Sang Hyun; Lee, In-Geun; Cho, Young-Dae; Shin, Hyun-Beom; Sung, Ho Kun; Park, Kyung Ho; Kang, Ho Kwan; Park, Won-Kyu; Park, Hyung-Ho

    2015-12-28

    A novel technique for the selective photochemical synthesis of silver (Ag) nanoparticles (NPs) on ZnO nanorod arrays is established by combining ultraviolet-assisted nanoimprint lithography (UV-NIL) for the definition of growth sites, hydrothermal reaction for the position-controlled growth of ZnO nanorods, and photochemical reduction for the decoration of Ag NPs on the ZnO nanorods. During photochemical reduction, the size distribution and loading of Ag NPs on ZnO nanorods can be tuned by varying the UV-irradiation time. The photochemical reduction is hypothesized to facilitate the adsorbed citrate ions on the surface of ZnO, allowing Ag ions to preferentially form Ag NPs on ZnO nanorods. The ratio of visible emission to ultraviolet (UV) emission for the Ag NP-decorated ZnO nanorod arrays, synthesized for 30 min, is 20.5 times that for the ZnO nanorod arrays without Ag NPs. The enhancement of the visible emission is believed to associate with the surface plasmon (SP) effect of Ag NPs. The Ag NP-decorated ZnO nanorod arrays show significant SP-induced enhancement of yellow-green light emission, which could be useful in optoelectronic applications. The technique developed here requires low processing temperatures (120 °C and lower) and no high-vacuum deposition tools, suitable for applications such as flexible electronics.

  19. Agglomeration in core-shell structure of CuAg nanoparticles synthesized by the laser ablation of Cu target in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Petrović, S.; Salatić, B.; Milovanović, D.; Lazović, V.; Živković, Lj; Trtica, M.; Jelenković, B.

    2015-02-01

    Metallic copper Cu and bimetallic copper-silver CuAg nanoparticles (NPs) are generated by the ablation of copper bulk target in water and aqueous Ag colloidal solution, respectively. The experiments were performed using nanosecond Nd:YAG laser operating at 1064 nm. The generated NPs are characterized by UV-vis absorption spectroscopy, laser-induced breakdown spectroscopy, dynamic lig