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1.
Int. microbiol ; 22(1): 49-58, mar. 2019. ilus, graf
Artigo em Inglês | IBECS | ID: ibc-184813

RESUMO

Green route for silver nanoparticle synthesis has gained increasing attention. Cyanobacteria are one of the promising organisms to produce a number of secondary metabolites that are capable of reducing silver ions to small-sized silver nanoparticles. In the present study, we employed an aqueous extract of the cyanobacterium Haloleptolyngbya alcalis KR2005/106 isolated from a soda lake for biosynthesis of silver nanoparticles (AgNPs). The extract acted as a reducing agent for AgNPs synthesis and resulted formation of nanoparticles <50 nm in size. In this study, synthesis of AgNPs obtained only in the sample exposed to photosynthetically active radiation (PAR) while the synthesis of AgNPs was not observed in the samples kept in dark. The biogenic fabrication of AgNPs was carried out by optimizing several governing parameters such as concentration of the silver nitrate solution, pH, temperature, and amount of biomass. Results obtained through different analytical techniques revealed that cyanobacterial taxon H. alcalis isolated from saline-alkaline habitat is a potential candidate for biosynthesis of optimum-sized spherical AgNPs. Surface plasmon resonance (SPR) property of AgNPs was exploited for aqueous ammonia sensing and revealed that AgNPs synthesized using aqueous extract of cyanobacterium H. alcalis could be employed for colorimetric detection of dissolved ammonia for monitoring quality of water


No disponible


Assuntos
Amônia/análise , Misturas Complexas/metabolismo , Cianobactérias/metabolismo , Nanopartículas Metálicas , Prata/metabolismo , Nitrato de Prata/metabolismo , Cianobactérias/isolamento & purificação , Escuridão , Lagos/microbiologia , Luz , Oxirredução , Ressonância de Plasmônio de Superfície
2.
Int Microbiol ; 22(1): 49-58, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30810931

RESUMO

Green route for silver nanoparticle synthesis has gained increasing attention. Cyanobacteria are one of the promising organisms to produce a number of secondary metabolites that are capable of reducing silver ions to small-sized silver nanoparticles. In the present study, we employed an aqueous extract of the cyanobacterium Haloleptolyngbya alcalis KR2005/106 isolated from a soda lake for biosynthesis of silver nanoparticles (AgNPs). The extract acted as a reducing agent for AgNPs synthesis and resulted formation of nanoparticles < 50 nm in size. In this study, synthesis of AgNPs obtained only in the sample exposed to photosynthetically active radiation (PAR) while the synthesis of AgNPs was not observed in the samples kept in dark. The biogenic fabrication of AgNPs was carried out by optimizing several governing parameters such as concentration of the silver nitrate solution, pH, temperature, and amount of biomass. Results obtained through different analytical techniques revealed that cyanobacterial taxon H. alcalis isolated from saline-alkaline habitat is a potential candidate for biosynthesis of optimum-sized spherical AgNPs. Surface plasmon resonance (SPR) property of AgNPs was exploited for aqueous ammonia sensing and revealed that AgNPs synthesized using aqueous extract of cyanobacterium H. alcalis could be employed for colorimetric detection of dissolved ammonia for monitoring quality of water.


Assuntos
Amônia/análise , Misturas Complexas/metabolismo , Cianobactérias/metabolismo , Nanopartículas Metálicas , Prata/metabolismo , Colorimetria/métodos , Cianobactérias/isolamento & purificação , Escuridão , Lagos/microbiologia , Luz , Oxirredução , Nitrato de Prata/metabolismo , Ressonância de Plasmônio de Superfície
3.
Microsc Res Tech ; 81(10): 1162-1164, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30277291

RESUMO

The present study, discusses a first report of staining techniques with silver nitrate (AgNO3 ) stain for the preservation and identification of myxozoans globally. The silver nitrate stain was used to prepare permanent slide preparation of myxozoans with some adaptations made in our laboratory. Fresh air dried smear were stained with silver nitrate stain ensuing dark brown color polar capsules and light brown color of spore-wall. The stain is everlasting for years differing to other stains like Geimsa, iron-heamotoxylin Zeihl-Neelsen Blue, and trichome stains. RESEARCH HIGHLIGHTS: Stains usually fade with time and fail to disclose the morphological characters of the specimen. Present staining method helps to detect less infection in the tissue locating the myxospores. The Klein dry method (1958) is useful and suitable for long term preservation of the myxozoan slides and morphological description.


Assuntos
Peixes/parasitologia , Myxozoa/anatomia & histologia , Doenças Parasitárias em Animais/parasitologia , Preservação de Tecido/métodos , Nadadeiras de Animais/parasitologia , Animais , Brânquias/parasitologia , Myxozoa/isolamento & purificação , Fotomicrografia , Nitrato de Prata/metabolismo , Coloração pela Prata , Pele/parasitologia
4.
Environ Toxicol Chem ; 37(11): 2895-2903, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30125984

RESUMO

The potential impact of silver nanoparticles (Ag NPs) on aquatic organisms is to a large extent determined by their bioavailability through different routes of exposure. In the present study juvenile Atlantic salmon (Salmo salar) were exposed to different sources of radiolabeled Ag (radiolabeled 110m Ag NPs and 110m AgNO3 ). After 48 h of waterborne exposure to 3 µg/L citrate stabilized 110m Ag NPs or 110m AgNO3 , or a dietary exposure to 0.6 mg Ag/kg fish (given as citrate stabilized or uncoated 110m Ag NPs, or 110m AgNO3 ), Ag had been taken up in fish regardless of route of exposure or source of Ag (Ag NPs or AgNO3 ). Waterborne exposure led to high Ag concentrations on the gills, and dietary exposure led to high concentrations in the gastrointestinal tract. Silver distribution to the target organs was similar for both dietary and waterborne exposure, with the liver as the main target organ. The accumulation level of Ag was 2 to 3 times higher for AgNO3 than for Ag NPs when exposure was through water, whereas no significant differences were seen after dietary exposure. The transfer (Bq/g liver/g food or water) from exposure through water was 4 orders of magnitude higher than from feed using the smallest, citrate-stabilized Ag NPs (4 nm). The smallest NPs had a 5 times higher bioavailability in food compared with the larger and uncoated Ag NPs (20 nm). Despite the relatively low transfer of Ag from diet to fish, the short lifetime of Ag NPs in water and their transfer to sediment, feed, or sediment-dwelling food sources such as larvae and worms could make diet a significant long-term exposure route. Environ Toxicol Chem 2018;37:2895-2903. © 2018 SETAC.


Assuntos
Exposição Ambiental/análise , Nanopartículas Metálicas/química , Radioisótopos/metabolismo , Salmo salar/metabolismo , Prata/metabolismo , Animais , Dieta , Feminino , Masculino , Tamanho da Partícula , Nitrato de Prata/metabolismo , Fatores de Tempo , Distribuição Tecidual , Poluentes Químicos da Água/análise
5.
Chem Biol Interact ; 291: 16-28, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29879413

RESUMO

p-CA is a naturally occurring phenolic acid present in most plants and in all commonly consumed vegetables and fruits. Here we demonstrated the anti-cancer effect of the food borne phytochemical p-CA both in vitro and in vivo models of colon cancer using growth rate and tumor incidence as endpoints. Glucose regulated protein (GRP78) induction and UPR activation plays a key role in oncogenic progression, therefore increased dependence of cancer cells on these UPR signaling pathways for survival can be exploited for anti-cancer research. Hence we investigated the effect of p-CA on Grp78 a molecular chaperone often upregulated in colon cancer and its impact on unfolded protein response (UPR). Administration of the procarcinogen 1,2- dimethylhydrazine (DMH) causes Grp78 upregulation and tumor adaptation via UPR activation. The adaptive activity of UPR activates antiapoptotic NF-κB that results in upregulation of the markers of inflammation and angiogenesis. Supplementation of p-CA downregulated Grp78 and activated UPR mediated apoptosis both in in vitro and in vivo models of colon cancer. Further we observed that p-CA significantly reduced inflammation by decreasing the expression of cytokines COX-2, IL-6, TNF-α and PGE2 as analyzed by q-PCR and also reduced the expression of p-p65 and p-IκBα as analyzed by western blot. Further mechanistic insights revealed that p-CA inhibits Grp78 upregulation in cancer cells through activation of PERK-eIF2α-ATF-4-CHOP pathway that culminates in apoptosis inducing effect of p-CA.


Assuntos
Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Regulação para Baixo/efeitos dos fármacos , Proteínas de Choque Térmico/metabolismo , Propionatos/farmacologia , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Colo/efeitos dos fármacos , Colo/metabolismo , Colo/patologia , Neoplasias do Colo/irrigação sanguínea , Neoplasias do Colo/tratamento farmacológico , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Humanos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Neovascularização Patológica/tratamento farmacológico , Neovascularização Patológica/patologia , Ratos Wistar , Transdução de Sinais/efeitos dos fármacos , Nitrato de Prata/metabolismo , Carga Tumoral/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/metabolismo
6.
Biomaterials ; 171: 97-106, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29684679

RESUMO

Silver nanomaterials are widely used in clinically approved devices, consumer goods, and over-the-counter nutraceutical products. Despite the increase in silver nanomaterial research, few investigations have specifically distinguished the biological effects resulting from silver nanoparticles (AgNPs) versus silver ions released from AgNPs. This is in part, due to the complex analytical methods required to characterize silver ion release from AgNPs in biological media. This study sought to analyze silver ion release from AgNPs in biological media, compare silver transport from soluble AgNO3 and AgNPs through ex vivo full thickness sinus human tissue explants and human nasal epithelium and determine fractional AgNP internalization by human nasal epithelial cells. Rapid silver ion release is observed from AgNPs in human nasal epithelial cell medium over 3 h (9.6% of total silver mass). Significantly lower translocation of AgNPs is observed through human nasal epithelial cell monolayers and ex vivo human sinus tissue explants compared to silver ion (AgNO3). AgNP internalization is directly observed in AgNP-exposed human nasal epithelial cell monolayers by live cell scanning transmission electron microscopy (STEM), providing one potential mechanism for AgNP transcytosis. However, in vitro AgNP dissolution experiments suggest that silver in human nasal epithelium is primarily silver ion. Ionic AgNO3 produces significantly higher silver translocation, supporting previous results claiming silver ion as primarily responsible for biological effects of AgNPs.


Assuntos
Nanopartículas Metálicas/química , Mucosa Nasal/metabolismo , Prata/metabolismo , Difusão Dinâmica da Luz , Humanos , Íons , Nanopartículas Metálicas/ultraestrutura , Nitrato de Prata/metabolismo
7.
J Biosci Bioeng ; 126(1): 44-52, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29496400

RESUMO

We examined the effect of various concentrations of HAuCl4, AgNO3, Na2SeO3, Na2SiO3, and GeO2 on mycelial growth of the soil basidiomycetes Agaricus bisporus and A. arvensis in submerged and solid media. Fungal mycelial extracts and cell-free culture filtrates were able to reduce ions of Au, Ag, Se, Si, and Ge compounds, forming Au0, Ag0, Se0, Si0/SiO2 and Ge0/GeO2 nanoparticles. The physical characteristics of the mycogenic nanoparticles differed depending on the species of Agaricus and the type of extract. Au nanospheres obtained with cell-free culture filtrates were of 2-5 nm diameter in A. bisporus and of 2-10 nm in A. arvensis. Nanoparticles produced by extracts of mycelia were several times larger and highly heterogenous. Ag nanoparticles produced by cell-free culture filtrates were spherical or irregular-shaped and agglomerated, whereas with extracts of mycelia, small homogenous nanospheres of 1-10 nm were formed. Se nanospheres obtained with cell-free culture filtrates were of 100-250 nm diameter in A. bisporus and of 150-550 nm diameter in A. arvensis. The particles synthesized with extracts of mycelia were of 40-140 nm in A. bisporus and of 100-250 nm in A. arvensis. Incubation of Na2SiO3 with cell-free culture filtrates resulted in porous Si nanoparticles of 30-65 nm in A. bisporus and of 50-200 nm in A. arvensis. Ge nanoparticles synthesized by both Agaricus species were mostly spheres of 50-250 nm diameter.


Assuntos
Agaricus/metabolismo , Nanopartículas/química , Nanopartículas/metabolismo , Agaricus/crescimento & desenvolvimento , Basidiomycota/metabolismo , Germânio/química , Germânio/metabolismo , Ouro/química , Micélio/crescimento & desenvolvimento , Micélio/metabolismo , Óxidos de Selênio/síntese química , Óxidos de Selênio/química , Óxidos de Selênio/metabolismo , Silício/química , Dióxido de Silício/síntese química , Dióxido de Silício/química , Dióxido de Silício/metabolismo , Prata/química , Nitrato de Prata/síntese química , Nitrato de Prata/química , Nitrato de Prata/metabolismo , Solo , Microbiologia do Solo
8.
Prep Biochem Biotechnol ; 48(2): 151-159, 2018 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-29313428

RESUMO

Biosynthesis of silver nanoparticles (AgNPs) using microorganisms is an important application of nanobiotechnology and green chemistry because of interest by pharmaceutical and food manufacturers. In this study, biosynthesis of AgNPs by a novel Bacillus strain isolated from a soil sample from Sakarya district in Turkey was investigated. Biosynthesis was performed using cell-free supernatant of the bacterium following 24 h growth. Effects of varying AgNO3 concentration (1-10 mM), pH (5-10), and temperature (30-40°C) on the synthesis of AgNPs were determined. Formation of AgNPs was monitored by UV-VIS spectroscopy. Field emission scanning electron microscopy was used to compare morphologies among the various culture conditions. The peaks created by surface plasmon resonance (SPR) of metals were obtained only at 4 and 6 mM AgNO3 concentrations and the maximum concentration for the biosynthesis was observed at 6 mM. The highest yield was achieved at pH 10 and larger nanoparticles were obtained at this pH. The optimum temperatures for biosynthesis were 33 and 37°C. Fourier transform infrared spectroscopy analysis and transmission electron microcopy images confirmed that the proteins served as capping. Energy-dispersive spectroscopy analysis validated the formation of AgNPs. AgNPs exhibited antibacterial activity toward Gram-positive and Gram-negative pathogens.


Assuntos
Antibacterianos/química , Bacillus/química , Química Verde/métodos , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Prata/química , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Bacillus/metabolismo , Bactérias/efeitos dos fármacos , Infecções Bacterianas/tratamento farmacológico , Humanos , Nanopartículas Metálicas/ultraestrutura , Prata/metabolismo , Prata/farmacologia , Nitrato de Prata/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente
9.
Prep Biochem Biotechnol ; 48(2): 103-112, 2018 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-28857662

RESUMO

As one kind of important secondary metabolites produced by Inonotus baumii, flavones can be applied in food, medicine, and other industries due to their biological activities such as antioxidant, anticancer, and antibacterial activity. To enhance total flavone production in submerged fermentation of I. baumii, three different strategies, optimization of fermentation parameters by statistical designs including Plackett-Burman design and response surface methodology, addition of precursors and elicitors, and two-phase culture, were used. The production of total flavones (PTF) reached 1532.83 mg/L when the optimized medium was used. All precursors and elicitors can increase the PTF. The maximum PTF (2184.06 mg/L, up to 1.57-fold) was obtained with the addition of both AgNO3 and glutathione in fermentation media. Interestingly, when 0.5% (w/v) DM130 macroporous resin as adsorbent was added to fermentation broth on day 4 of culture, the highest production reached 2407.79 mg/L with this two-phase culture strategy. These methods can be further applied to large-scale industrial production and broaden the application of flavones.


Assuntos
Basidiomycota/metabolismo , Flavonas/metabolismo , Microbiologia Industrial/métodos , Meios de Cultura/metabolismo , Fermentação , Glutationa/metabolismo , Modelos Biológicos , Modelos Estatísticos , Nitrato de Prata/metabolismo
10.
Int J Nanomedicine ; 12: 6373-6381, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28919741

RESUMO

The biosynthesis of metallic nanoparticles (NPs) using biological systems such as fungi has evolved to become an important area of nanobiotechnology. Herein, we report for the first time the extracellular synthesis of highly stable silver NPs (AgNPs) using the nematophagous fungus Duddingtonia flagrans (AC001). The fungal cell-free filtrate was analyzed by the Bradford method and 3,5-dinitrosalicylic acid assay and used to synthesize the AgNPs in the presence of a 1 mM AgNO3 solution. They have been characterized by UV-Vis spectroscopy, X-ray diffraction, transmission electron microscopy, dynamic light scattering, Zeta potential measurements, Fourier-transform infrared, and Raman spectroscopes. UV-Vis spectroscopy confirmed bioreduction, while X-ray diffractometry established the crystalline nature of the AgNPs. Dynamic light scattering and transmission electron microscopy images showed approximately 11, 38 nm monodisperse and quasispherical AgNPs. Zeta potential analysis was able to show a considerable stability of AgNPs. The N-H stretches in Fourier-transform infrared spectroscopy indicate the presence of protein molecules. The Raman bands suggest that chitinase was involved in the growth and stabilization of AgNPs, through the coating of the particles. Our results show that the NPs we synthesized have good stability, high yield, and monodispersion.


Assuntos
Duddingtonia/metabolismo , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Prata/química , Sistema Livre de Células , Difusão Dinâmica da Luz , Microscopia Eletrônica de Transmissão , Prata/metabolismo , Nitrato de Prata/química , Nitrato de Prata/metabolismo , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Difração de Raios X
11.
Ecotoxicol Environ Saf ; 144: 330-337, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28646738

RESUMO

Standard natural Lufa soils (2.2, 2.3 and 5M) with different organic carbon contents (0.67-1.61%) and pHCaCl2 (5.5-7.3) were spiked with ionic Ag (AgNO3) and polyvinyl pyrrolidone (AgNP-PVP) and citrate (AgNP-Cit) coated Ag nanoparticles (NPs). Enchytraeus crypticus were exposed for 21 days to assess effects on survival and reproduction. Soil, pore water and animals were analyzed for Ag. AgNP-Cit had a strong increasing effect on soil pH, leading to high enchytraeid mortality at concentrations higher than 60-100mg Ag/kg dry soil which made it impossible to determine the influence of soil properties on its toxicity. LC50s were lower for AgNO3 than for AgNP-PVP (92-112 and 335-425mg Ag/kg dry soil, respectively) and were not affected by soil properties. AgNO3 and AgNP-PVP had comparable reproductive toxicity with EC50s of 26.9-75.2 and 28.2-92.3mg Ag/kg dry soil, respectively; toxicity linearly increased with decreasing organic carbon content of the soils but did not show a clear effect of soil pH. Ag uptake in the enchytraeids was higher at higher organic carbon content, but could not explain differences in toxicity between soils. This study indicates that the bioavailability of both ionic and nanoparticulate Ag is mainly affected by soil organic carbon, with little effect of soil pH.


Assuntos
Nanopartículas Metálicas/toxicidade , Oligoquetos/efeitos dos fármacos , Prata/toxicidade , Poluentes do Solo/toxicidade , Solo/química , Animais , Disponibilidade Biológica , Ácido Cítrico/química , Relação Dose-Resposta a Droga , Íons , Dose Letal Mediana , Oligoquetos/metabolismo , Povidona/química , Reprodução/efeitos dos fármacos , Prata/metabolismo , Nitrato de Prata/metabolismo , Nitrato de Prata/toxicidade , Solo/normas , Poluentes do Solo/metabolismo
12.
Artif Cells Nanomed Biotechnol ; 45(3): 602-608, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28211298

RESUMO

Simple, facile, effective approach for the biosynthesis of silver nanoparticles using Kinneretia species and its antimicrobial activity against human pathogens has been demonstrated in this study. Kinneretia THG-SQI4 has been isolated from soil sample collected from Shangqui, China. The synthesized nanoparticles were characterized by ultraviolet-visible spectrophotometry (UV-vis), field emission transmission electron microscopy (FE-TEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping, selected area diffraction pattern, and X-ray diffraction (XRD). The synthesized silver nanoparticles were characterized by a peak at 425 nm in the UV-vis spectrum. The TEM data reveals that the nanoparticles are monodisperse and spherical in shape having a diameter ranging from 15 to 20 nm. The bright circular spots in SAED pattern confirm the crystalline nature of the nanoparticles. The XRD spectra exhibited the characteristic Bragg peaks of 1 1 1, 2 0 0, 2 2 0, and 3 1 1 facets of the face centered cubic symmetry of nanoparticles. The synthesized silver nanoparticles showed potent antibacterial activity against human pathogens like Candida albicans, Candida tropicalis, Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Salmonella enterica, Pseudomonas aeruginosa, Escherichia coli, and Vibrio parahaemolyticus. Moreover, the silver nanoparticles show enhanced synergistic effects in combination with different standard antibiotics against Gram-negative bacteria. This method for synthesis of silver nanoparticle is valuable and has antimicrobial potential.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Comamonadaceae/química , Química Verde , Nanopartículas Metálicas/toxicidade , Nitrato de Prata/química , Antibacterianos/química , Antifúngicos/química , Candida/efeitos dos fármacos , Candida/crescimento & desenvolvimento , Comamonadaceae/fisiologia , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Sinergismo Farmacológico , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/crescimento & desenvolvimento , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/crescimento & desenvolvimento , Macrolídeos/farmacologia , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Tamanho da Partícula , Nitrato de Prata/metabolismo , Vancomicina/farmacologia , beta-Lactamas/farmacologia
13.
Environ Pollut ; 222: 50-57, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28089465

RESUMO

With the increasing application in antimicrobial products, silver nanoparticles (AgNP) are inevitably released into the terrestrial environment, and pose potential risks to invertebrates such as land snails Achatina fulica, which take up AgNP from food and water. Here we differentiate Ag uptake biodynamic between Ag forms (i.e., PVP-AgNP vs. AgNO3) and between exposure pathways. Snails assimilated Ag efficiently from lettuce leaves pre-exposed to AgNP, with assimilation efficiencies (AEs) averaging 62-85% and food ingestion rates of 0.11 ± 0.03 g g-1 d-1. Dietary Ag bioavailability was independent on Ag forms, as revealed by comparable AEs between AgNP and AgNO3. However, the uptake rate constant from water was much lower for AgNP relative to AgNO3 (2 × 10-4 vs. 0.12 L g-1 d-1). The elimination rate constants were 0.0093 ± 0.0037 d-1 for AgNP and 0.019 ± 0.0077 d-1 for AgNO3. Biodynamic modeling further showed that dietary exposure was the dominant uptake pathway for AgNP in most circumstances, while for AgNO3 the relative importance of waterborne and dietary exposure depended on Ag concentrations in food and water. Our findings highlight the importance of dietary uptake of AgNP during bioaccumulation, which should be considered in the risk assessment of these nanoparticles.


Assuntos
Disponibilidade Biológica , Alface/química , Nitrato de Prata/metabolismo , Prata/metabolismo , Caramujos/metabolismo , Animais , China , Nanopartículas Metálicas
14.
Environ Toxicol ; 32(2): 609-618, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26996539

RESUMO

The increasing application of silver nanoparticles (AgNPs) has been raising concerns about their potential adverse effects to human and the environment. However, the knowledge on the systemic toxicity of AgNPs in mammalian systems is still limited. The present study investigated the toxicity of PVP-coated AgNPs in rats treated with repeated oral administration, and compared that with equivalent dose of AgNO3 . Specifically, one hundred male and female rats were orally administrated with particulate or ionic forms of silver (Ag) separately at doses of 0.5 and 1 mg kg-1 body weight daily for 28 days. The results reveal no significant toxic effects of AgNPs and AgNO3 up to 1 mg kg-1 body weight, with respect to the body weight, organ weight, food intake, and histopathological examination. Ag distribution pattern in organs of rats treated with AgNPs was similar to that of AgNO3 treated rats, showing liver and kidneys are the main target organs followed by testis and spleen. The total Ag contents in organs were significantly lower in the AgNPs treated rats than those in the AgNO3 treated rats. However, the comparisons between AgNPs and AgNO3 treatments further indicated more potent of AgNPs in biochemical and hematological parameters in rats, including red blood cell count (RBC), platelet count (PLT), white blood cell count (WBC) and aspartate transaminase (AST). Results of this study suggested that particulate Ag at least partially contributed to the observed toxicity of AgNPs, and both ionic and particulate Ag should be taken into consideration in toxicological evaluation of AgNPs. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 609-618, 2017.


Assuntos
Poluentes Ambientais/toxicidade , Nanopartículas Metálicas/toxicidade , Nitrato de Prata/toxicidade , Alanina Transaminase/sangue , Animais , Aspartato Aminotransferases/sangue , Poluentes Ambientais/metabolismo , Feminino , Rim/efeitos dos fármacos , Rim/metabolismo , Rim/patologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Tamanho do Órgão/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Nitrato de Prata/metabolismo , Baço/efeitos dos fármacos , Baço/metabolismo
15.
Artif Cells Nanomed Biotechnol ; 45(3): 584-590, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27027821

RESUMO

Silver nanoparticles were prepared through green route with the aid of Aeromonas sp. THG-FG1.2 as reductant. Visual observation, ultraviolet-visible spectroscopy, transmission electron microscopy, elemental mapping, energy dispersive X-ray spectroscopy, selected area diffraction pattern (SAED), and X-ray diffraction (XRD) were used to characterize the synthesized silver nanoparticles. UV visible studies indicated the surface plasmon resonance at 400 nm which depicts the formation of silver nanoparticles. The TEM images show spherical silver nanoparticles of 8-16 nm. XRD and SAED fringes revealed the structure of silver nanoparticles as face centered cubic (fcc). These silver nanoparticles also tested for their antimicrobial potential and showed effective antimicrobial activity against tested pathogens and thus applicable as potent antimicrobial agent. Furthermore, the nanoparticles potential has been reconnoitered for their enhanced synergistic effect with antibiotics against multidrug resistant bacteria. Thus, the silver nanoparticles synthesized by Aeromonas sp. THG-FG1.2, were effective in inhibition of pathogenic microbes and also show enhanced antibacterial activity with antibiotics.


Assuntos
Aeromonas/química , Antibacterianos/farmacologia , Antifúngicos/farmacologia , Química Verde , Nanopartículas Metálicas/toxicidade , Nitrato de Prata/química , Aeromonas/fisiologia , Antibacterianos/química , Antifúngicos/química , Candida/efeitos dos fármacos , Candida/crescimento & desenvolvimento , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Sinergismo Farmacológico , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/crescimento & desenvolvimento , Bactérias Gram-Positivas/efeitos dos fármacos , Bactérias Gram-Positivas/crescimento & desenvolvimento , Macrolídeos/farmacologia , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Tamanho da Partícula , Nitrato de Prata/metabolismo , Vancomicina/farmacologia , beta-Lactamas/farmacologia
16.
Environ Pollut ; 222: 251-260, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28034561

RESUMO

Zebra mussels (Dreissena polymorpha) were exposed to polyvinylpyrrolidone (PVP)-coated silver nanoparticles (AgNP; hydrodynamic diameter 80 nm; solid diameter 50 nm) to investigate the behavior of Ag in the tank water with respect to its uptake, bioaccumulation, elimination and subcellular distribution in the mussel soft tissue. Parallel experiments were performed with ionic Ag (AgNO3) to unravel possible differences between the metal forms. The recovery of the applied Ag concentration (500 µg/L) in the tank water was clearly affected by the metal source (AgNP < AgNO3) and water type (reconstituted water < tap water). Filtration (<0.45 µm) of water samples showed different effects on the quantified metal concentration depending on the water type and Ag form. Ag accumulation in the mussel soft tissue was neither influenced by the metal source nor by the water type. Ag concentrations in the mussel soft tissue did not decrease during 14 days of depuration. For both metal forms the Ag distribution within different subcellular fractions, i.e. metal-rich granules (MRG), cellular debris, organelles, heat-sensitive proteins (HSP) and metallothionein-like proteins (MTLP), revealed time-dependent changes which can be referred to intracellular Ag translocation processes. The results provide clear evidence for the uptake of Ag by the mussel soft tissue in nanoparticulate as well as in ionic form. Thus, zebra mussels could be used as effective accumulation indicators for environmental monitoring of both Ag forms.


Assuntos
Dreissena/citologia , Dreissena/metabolismo , Água Doce/química , Nanopartículas Metálicas/análise , Nanopartículas Metálicas/química , Prata/química , Prata/metabolismo , Animais , Disponibilidade Biológica , Metalotioneína/metabolismo , Prata/farmacocinética , Nitrato de Prata/química , Nitrato de Prata/metabolismo , Nitrato de Prata/farmacocinética , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/farmacocinética
17.
Sci Rep ; 6: 24459, 2016 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-27074820

RESUMO

High quality cadmium-free Zn-In-S:Ag doped-nanocrystals (d-NCs) were synthesized via a simple one-step noninjection route using silver nitrate, indium acetate, zinc acetate, oleylamine, S powder and 1-dodecanethiol as starting materials in an organic phase. The size and optical properties can be effectively tailored by controlling the reaction time, reaction temperature, Ag(+) dopant concentration, and the molar ratio of In to Zn. The photoluminescence wavelength of as-prepared Zn-In-S:Ag NCs covered a broad visible range from 458 nm to 603 nm. After being passivated by protective ZnS shell, the photoluminescence quantum yield (PLQY) of Zn-In-S:Ag(+) /ZnS was greatly improved to 43.5%. More importantly, the initial high PLQY of the obtained core/shell d-NCs in organic media can be preserved when being transferred into the aqueous media via ligand exchange. Finally, high quality Zn-In-S:Ag(+) /ZnS d-NCs in aqueous phase were applied as bio-imaging agents for identifying living KB cells.


Assuntos
Índio/metabolismo , Nanopartículas/metabolismo , Imagem Óptica/métodos , Nitrato de Prata/metabolismo , Enxofre/metabolismo , Acetato de Zinco/metabolismo , Aminas/metabolismo , Medições Luminescentes , Compostos de Sulfidrila/metabolismo , Temperatura Ambiente , Fatores de Tempo
19.
Mycoses ; 59(3): 157-66, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26671603

RESUMO

Superficial mycoses are limited to the most external part of the skin and hair and caused by Malassezia sp., Trichophyton sp. and Candida sp. We report extracellular biosynthesis of silver nanoparticles (AgNPs) by acidophilic actinobacteria (SF23, C9) and its in vitro antifungal activity against fungi-causing superficial mycoses. The phylogenetic analysis based on the 16S rRNA gene sequence of strains SF23 and C9 showed that they are most closely related to Pilimelia columellifera subsp. pallida GU269552(T). The detection of AgNPs was confirmed by visual observation of colour changes from colourless to brown, and UV-vis spectrophotometer analysis, which showed peaks at 432 and 427 nm, respectively. These AgNPs were further characterised by nanoparticle tracking analysis (NTA), Zeta potential, Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The FTIR analysis exhibited the presence of proteins as capping agents. The TEM analysis revealed the formation of spherical and polydispersed nanoparticles in the size range of 4-36 nm and 8-60 nm, respectively. The biosynthesised AgNPs were screened against fungi-causing superficial mycoses viz., Malassezia furfur, Trichophyton rubrum, Candida albicans and C. tropicalis. The highest antifungal activity of AgNPs from SF23 and C9 against T. rubrum and the least against M. furfur and C. albicans was observed as compared to other tested fungi. The biosynthesised AgNPs were found to be potential anti-antifungal agent against fungi-causing superficial mycoses.


Assuntos
Actinobacteria/metabolismo , Antifúngicos/uso terapêutico , Dermatomicoses/tratamento farmacológico , Nanopartículas Metálicas/química , Actinobacteria/classificação , Actinobacteria/genética , Algoritmos , Antifúngicos/farmacologia , Sequência de Bases , Candida albicans/efeitos dos fármacos , Candida tropicalis/efeitos dos fármacos , Dermatomicoses/microbiologia , Sinergismo Farmacológico , Humanos , Cetoconazol/farmacologia , Cetoconazol/uso terapêutico , Malassezia/efeitos dos fármacos , Nanopartículas Metálicas/uso terapêutico , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Microscopia Eletrônica de Transmissão , RNA Ribossômico 16S/genética , Prata , Nitrato de Prata/metabolismo , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Trichophyton/efeitos dos fármacos
20.
J Basic Microbiol ; 56(5): 531-40, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26515502

RESUMO

An eco-friendly process for the silver nanoparticles (Ag-NPs) biosynthesis was investigated using the fungus Monascus purpureus as a safe and commercially used microorganism. M. purpureus growth filtrate was used for the reduction of the aqueous silver nitrate into Ag-NPs with almost 100% size range of 1-7 nm, which was considered as one of the smallest microbial biosynthesized Ag-NPs. The biosynthesized Ag-NPs were structurally characterized using UV, FTIR, DLS, TEM, and XRD. The biosynthesized Ag-NPs were stable after 3 months with no alteration in shape or size. M. purpureus showed no nitrate reductase activity, whereas its pigments reducing power was decreased after nanoparticles formation indicating its role in the Ag-NPs biosynthesis. The synthesized Ag-NPs exhibited strong antimicrobial activity against different bacteria and yeasts species. The anti-Candida activity of M. purpureus culture filtrate was enhanced in the presence of Ag-NPs; the maximum increase in microbial inhibition was observed against Candida albicans with 1.73 increased folds of inhibition zones, followed by their activity against C. tropicalis and C. glabrata with 0.919- and 0.694-folds of increase, respectively. The obtained results suggest that the biosynthesized Ag-NPs offers a promising cost-effective, eco-friendly, and an alternative way to the conventional method of synthesis that could have wide applications in medicine.


Assuntos
Antifúngicos/farmacologia , Candida albicans/crescimento & desenvolvimento , Meios de Cultivo Condicionados/farmacologia , Nanopartículas Metálicas , Monascus/metabolismo , Prata/farmacologia , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Antifúngicos/metabolismo , Bactérias/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Nitrato Redutase/metabolismo , Nitrato de Prata/metabolismo , Difração de Raios X
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