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1.
Bull Environ Contam Toxicol ; 105(2): 244-249, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32556691

RESUMO

The aim of the study was to assess the effects of silver nanoparticles (AgNPs1 = 2.7 d·nm, AgNPs2 = 6.5 d·nm) and silver nitrate (AgNO3) on Enchytraeus crypticus and Folsomia candida using toxicity tests (OECD Guideline 220, 232). A 28-day chronic toxicity study was performed to evaluate the reproduction and mortality rate. E. crypticus reproduction was more sensitive to AgNO3 with a 28dEC50 of 86.40 (62.52-119.4) mg·kg-1 dry weight (d.w.) compared to AgNPs1 (28dEC50 = 119.3 (60.4-235.6) mg·kg-1 d.w). Similarly, the reproduction of F. candida was inhibited the most by AgNO3 with a 28dEC50 of 126.2 (104.2-152.9) mg·kg-1 d.w. followed by AgNPs1 (28dEC50 = 158.7 (64.05-393.2) mg·kg-1 d.w.) and AgNPs2 (28dEC50 = 206.4 (181.9-234.1) mg·kg-1 d.w.). No mortalities were observed for tested soil invertebrates exposed to AgNPs at concentrations up to 166 mg·kg-1 d.w. of AgNPs1 and 300 mg·kg-1 d.w. of AgNPs2, respectively. It was found that silver ions are more toxic in comparison with AgNPs.


Assuntos
Artrópodes/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Oligoquetos/efeitos dos fármacos , Nitrato de Prata/toxicidade , Prata/toxicidade , Poluentes do Solo/toxicidade , Animais , Íons , Nanopartículas Metálicas/química , Reprodução/efeitos dos fármacos , Prata/química , Solo/química , Solo/normas , Poluentes do Solo/química , Testes de Toxicidade Crônica
2.
Ecotoxicol Environ Saf ; 200: 110745, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32460051

RESUMO

Chronic dietary bioaccumulation tests with rodents are required for new substances, including engineered nanomaterials (ENMs), in order to provide information on the potential hazards to human health. However, screening tools are needed to manage the diversity of ENMs and alternative methods are desirable with respect to animal welfare. Here, an ex vivo gut sac method was used to estimate the dietary bioaccumulation potential of silver nanomaterials. The entire gastrointestinal tract (except the caecum) was removed and filled with a gut saline containing 1 mg L-1 of Ag as either AgNO3, silver nanoparticles (Ag NPs) or silver sulphide nanoparticles (Ag2S NPs), and compared to controls with no added Ag. The gut sacs were incubated for 4 h, rinsed to remove excess media, and the total Ag determined in the mucosa and muscularis. There was no detected Ag in the control treatments. Within the Ag treatments, 1.4-22% of the exposure dose was associated with the tissues and serosal saline. Within the mucosa of the AgNO3 treatment, the highest Ag concentration was associated with the intestinal regions (3639-7087 ng g-1) compared to the stomach (639 ± 128 ng g-1). This pattern was also observed in the Ag NP and Ag2S NP treatments, but there was no significant differences between any Ag treatments for the mucosa. However, differences between treatments were observed in the muscularis concentration. For example, both the Ag NP (907 ± 284 ng g -1) and Ag2S NP (1482 ± 668 ng g-1) treatments were significantly lower compared to the AgNO3 treatment (2514 ± 267 ng g-1). The duodenum demonstrated serosal accumulation in both the AgNO3 (~10 ng mL-1) and Ag NP (~3 ng mL-1) treatments. The duodenum showed some of the highest Ag accumulation with 41, 61 and 57% of the total Ag in the mucosa compared to the muscularis for the AgNO3, Ag NP and Ag2S NP treatments, respectively. In conclusion, the ex vivo gut sac method demonstrates the uptake of Ag in all Ag treatments, with the duodenum the site of highest accumulation. Based on the serosal saline accumulation, the ranked order of accumulation is AgNO3 > Ag NPs > Ag2S NPs.


Assuntos
Trato Gastrointestinal/metabolismo , Nanopartículas Metálicas , Compostos de Prata/metabolismo , Nitrato de Prata/metabolismo , Prata/metabolismo , Animais , Bioacumulação , Dieta , Intestinos , Membrana Mucosa/metabolismo , Ratos Wistar , Estômago
3.
Sci Total Environ ; 728: 138611, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32344222

RESUMO

The use of colloidal silver-containing products as dietary supplements, immune boosters and surface disinfectants has increased in recent years which has elevated the potential for human exposure to silver nanoparticles and ions. Product mislabeling and long-term use of these products may put consumers at risk for adverse health outcomes including argyria. This study assessed several physical and chemical characteristics of five commercial products as well as their cytotoxicity using a rat intestinal epithelial cell (IEC-6) model. Concentrations of silver were determined for both the soluble and particulate fractions of the products. Primary particle size distribution and elemental composition were determined by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. Hydrodynamic diameters were measured using nanoparticle tracking analysis (NTA) and dynamic light scattering (DLS). The effect of gastrointestinal (GI) simulation on the colloidal silver products was determined using two systems. First, physical and chemical changes of the silver nanoparticles in these products was assessed after exposure to Synthetic Stomach Fluid (SSF) resulting in particle agglomeration, and the appearance of AgCl on the surfaces and between particles. IEC-6 cells were exposed for 24 h to dilutions of the products and assessed for cell viability. The products were also treated with a three-stage simulated GI system (stomach and intestinal fluids) prior to exposure of the IEC-6 cells to the isolated silver nanoparticles. Cell viability was affected by each of the consumer products. Based on the silver nitrate and commercial silver nanoparticle dose response, the cytotoxicity for each of the colloidal silver products was attributed to the particulate silver, soluble silver or non­silver matrix constituents.


Assuntos
Desinfetantes , Nanopartículas Metálicas , Animais , Humanos , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Ratos , Prata , Nitrato de Prata
4.
Sci Total Environ ; 725: 138433, 2020 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-32302844

RESUMO

Silver nanoparticles (AgNPs) are commonly utilized industrial compounds mostly because of their antimicrobial properties. Nevertheless, our understanding of their potential developmental toxicity in humans is still limited. Embryonic stem cells (ESCs) are powerful in vitro tools for developmental toxicity assessments of chemicals. Here, we evaluated the potential developmental toxicity during early embryogenesis of AgNPs and AgNO3 with human ESC (hESC)-based differentiation systems in vitro. We found that human relevant concentrations of AgNPs and Ag ions affected the specification of two of the three primary germ layers, endoderm and mesoderm, without drastically affecting ectoderm. Furthermore, the two forms of Ag impaired the generation and functions of hepatocytes-like cells derived from endoderm, by decreasing the expression of important liver markers such as AFP, ALB, and HNF4A, and altering glycogen storage. When considering cardiac development, AgNPs and AgNO3 manifested opposite adverse effects, in that AgNPs increased while AgNO3 decreased the expression of typical cardiac markers (NKX2.5, MYH6, and ISL) in hESC-derived cardiomyocytes. In conclusion, our findings argue for a potential developmental toxicity of AgNP doses we are exposed to, or levels detected in the human body, especially at very early stages during embryogenesis, and which may not be just due to Ag leakage. Moreover, mesendoderm-derived cell types, tissues and organs may be more prone to AgNP toxicity than ectoderm lineages.


Assuntos
Nanopartículas Metálicas , Prata , Hepatócitos , Humanos , Miócitos Cardíacos , Nitrato de Prata
5.
Environ Pollut ; 262: 114277, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32163806

RESUMO

Silver (Ag) is amongst the most well studied nanomaterials (NMs), although most studies have only dealt with a single AgNM at a time and one biological endpoint. We here integrate the results of various testing-tools (endpoints) using a terrestrial worm, the standard ecotoxicological model organism Enchytraeus crypticus. Exposure spanned both water and soil exposure, it covered all life stages (cocoons, juveniles and adults), varying exposure durations (1-2-3-4-5-21 days), and covered 5 biological endpoints: hatching success, survival, reproduction, avoidance and gene expression (qPCR target genes GABA and Acetyl cholinesterase). We tested 4 Ag materials: PVP coated (PVP-AgNM), non-coated (NC-AgNM), the JRC reference Ag NM300K and AgNO3. Results showed that short-term exposure via water to assess impact on cocoons' hatching predicted longer term effects such as survival and reproduction. Moreover, if we extended the exposure from 11 to 17 day this allowed discrimination between hatch delay and impairment. Exposure of juveniles and adults via water showed that juveniles were most sensitive with survival affected. Across materials the following toxic ranking was observed: AgNO3 ≥ Ag NM300K â‰« NC-AgNM ≥ PVP-AgNM. E. crypticus avoided AgNO3 in a dose-response manner, avoiding most during the first 24 h. Avoidance of Ag NM300K and NC-AgNM only occurred during the first 24 h and the PVP coated AgNM were not avoided at all. The up-regulation of the GABA triggering anesthetic effects, indicated the high ecological impact of Ag materials in soil: Ag affects the GABAergic system hence organisms were not able to efficiently avoid and became intoxicated, this caused impacts in terms of survival and reproduction.


Assuntos
Nanopartículas Metálicas , Oligoquetos , Poluentes do Solo/análise , Animais , Estágios do Ciclo de Vida , Reprodução , Prata , Nitrato de Prata
6.
Sci Total Environ ; 721: 137665, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32169641

RESUMO

The current study provides an in vivo analysis of the production of reactive oxygen species (ROS) and oxidative stress in the nematode Caenorhabditis elegans following exposure to EU reference silver nanoparticles NM300K and AgNO3. Induction of antioxidant defenses was measured through the application of a SOD-1 reporter, and the HyPer and GRX biosensor strains to monitor changes in the cellular redox state. Both forms of Ag resulted in an increase in sod-1 expression, elevated H2O2 levels and an imbalance in the cellular GSSG/GSH redox status. Microscopy analysis of the strains revealed that AgNO3 induced ROS-related effects in multiple tissues, including the pharynx, intestinal cells and muscle tissues. In contrast, NM300K resulted in localized ROS production and oxidative stress, specifically in tissues surrounding the intestinal lumen. This indicates that Ag from AgNO3 exposure was readily transported across the whole body, while Ag or ROS from NM300K exposure was predominantly confined within the luminal tissues. Concentrations resulting in an increase in ROS production and changes in GSSG/GSH ratio were in line with the levels associated with observed physiological toxic effects. However, sod-1 was not induced at the lowest Ag concentrations, although reprotoxicity was seen at these levels. While both forms of Ag caused oxidative stress, impaired development, and reprotoxicity, the results suggest different involvement of ROS production to the toxic effects of AgNO3versus NM300K.


Assuntos
Nanopartículas Metálicas , Prata , Animais , Caenorhabditis elegans , Peróxido de Hidrogênio , Oxirredução , Estresse Oxidativo , Espécies Reativas de Oxigênio , Nitrato de Prata
7.
Int J Nanomedicine ; 15: 49-63, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32021164

RESUMO

Background: The emergence of multi drug-resistant (MDR) bacterial infections and cancer has necessitated the development and discovery of alternative eco-safe antibacterial and anticancer agents. Biogenic fabrication of metallic nanoparticles is an emerging discipline for production of nanoproducts that exert potent anticancer and antibacterial activity, and do not suffer from the limitations inherent in physiochemical synthesis methods. Methodology: In this study, we isolated, purified, and characterized a novel cyanobacteria extract (Desertifilum IPPAS B-1220) to utilize in biofabrication of silver nanoparticles (D-SNPs). D-SNPs were produced by adding Desertifilum extract to silver nitrate solution under controlled conditions. Biofabrication of D-SNPs was confirmed using a UV-Vis spectrophotometer. The resultant D-SNPs were characterized using XRD, FTIR, SEM, and TEM. The toxicity of D-SNPs against five pathogenic bacteria and three cancer cell lines (MCF-7, HepG2, and Caco-2) was evaluated. Results: Formation of D-SNPs was indicated by a color change from pale yellow to dark brown. The peak of the surface plasmon resonance of the D-SNPs was at 421 nm. The XRD detected the crystallinity of D-SNPs. FTIR showed that polysaccharides and proteins may have contributed to the biofabrication of D-SNPs. Under SEM and TEM, the D-SNPs were spherical with diameter ranges from 4.5 to 26 nm. The D-SNPs significantly suppressed the growth of five pathogenic bacteria, and exerted cytotoxic effects against MCF-7, HepG2, and Caco-2 cancer cells with IC50 values of 58, 32, and 90 µg/mL, respectively. Conclusion: These findings showed for the first time the potentiality of novel cyanobacteria strain Desertifilum IPPAS B-1220 to fabricate small SNPs that acted as potent anticancer and antibacterial material against different cancer cell lines and pathogenic bacterial strains. These findings encourage the researchers to focus on cyanobacteria in general and especially Desertifilum sp. IPPAS B-1220 for synthesizing different NPs that opening the window for new applications.


Assuntos
Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Cianobactérias/química , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/química , Antineoplásicos/química , Células CACO-2 , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Avaliação Pré-Clínica de Medicamentos , Células Hep G2 , Humanos , Células MCF-7 , Testes de Sensibilidade Microbiana , Extratos Vegetais/química , Nitrato de Prata/química , Espectroscopia de Infravermelho com Transformada de Fourier , Ressonância de Plasmônio de Superfície
8.
Food Chem ; 317: 126433, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32092613

RESUMO

Highly catalytic and stable N-doped carbon dots (N-CDs) were prepared rapidly by microwave procedure using glucose as precursor and ammonium sulfite as N-dopant. The reduction of AgNO3 by trisodium citrate (TCA) was slow to form nanosilver (AgNP), and the N-CDs exhibited strong catalysis of the AgNP reaction. The formed AgNPs were used as indicator in the presence of Vitoria blue B (VBB) molecule probe with a SERS peak at 1615 cm-1. With the increase of nancatalyst N-CDs concentration, the AgNP reaction speed up, and the SERS peak of VBB enhanced linearly due to formation of more AgNPs as substrate. In the presence of avidin (Ad), the SERS peak weakened. Upon addition of biotin, the SERS peak enhanced due to turn on the indicator nanoreaction. The enhanced SERS signal had a good linear relationship with the biotin concentration in range of 0.0006-0.021 ng/mL, with a detection limit of 0.3 pg/mL.


Assuntos
Biotina/análise , Análise de Alimentos/métodos , Prata/química , Análise Espectral Raman/métodos , Animais , Avidina/química , Carbono/química , Catálise , Citratos/química , Análise de Alimentos/instrumentação , Limite de Detecção , Nanopartículas Metálicas/química , Leite/química , Técnicas de Sonda Molecular/instrumentação , Sondas Moleculares/química , Compostos Orgânicos/química , Pontos Quânticos/química , Nitrato de Prata/química , Análise Espectral Raman/instrumentação
9.
J Laryngol Otol ; 134(3): 222-227, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32066510

RESUMO

OBJECTIVE: This study compared the efficacy of microwave ablation and silver nitrate cautery as treatments for idiopathic recurrent anterior epistaxis in adults. METHODS: A case series with chart review was conducted. Adults with recurrent anterior epistaxis intra-operatively treated via microwave ablation or silver nitrate chemical cautery of the anterior nasal septum were enrolled. The primary outcomes were the proportion of patients in each group for whom bleeding ceased within 24 hours of treatment, and the time to successful haemostasis. The secondary outcomes were re-bleeding rates at 1 and 12 weeks and 6 months, and complications. RESULTS: The haemostasis success rate within 24 hours' treatment of convex lesions was significantly higher in the microwave ablation group than in the cautery-only group. Of patients with convex lesions, the recurrence rate to six months was significantly higher in the cautery group than in the microwave ablation group, but this was not the case for those with flat lesions. CONCLUSION: Microwave ablation afforded rapid and simple haemostasis for adults with recurrent anterior epistaxis in an out-patient setting. Microwave ablation had significant advantages compared to silver nitrate cautery when used to treat epistaxis in patients with convex lesions.


Assuntos
Cauterização/métodos , Epistaxe/cirurgia , Hemostasia Cirúrgica/métodos , Micro-Ondas/uso terapêutico , Ablação por Radiofrequência/métodos , Adulto , Feminino , Humanos , Masculino , Septo Nasal/cirurgia , Nitrato de Prata/administração & dosagem , Resultado do Tratamento
10.
An Bras Dermatol ; 95(1): 46-51, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31901368

RESUMO

BACKGROUND: Organoid cultures are primary cultures that maintain architectural characteristics and the relationships between cells, as well as the extracellular matrix. They are alternatives for pathophysiological or therapeutic investigation rather than animal and in vitro tests. OBJECTIVE: Development of a cutaneous organoid culture model, aiming at the study of radiation-induced melanogenesis. METHOD: A validation study, which involved biopsies of the skin of the back of the adult ear. One sample was irradiated with different doses of UVB, UVA, or visible light (VL); the other was maintained in the dark for 72h. The viability of the tissues was evaluated from the morphological and architectural parameters of the histology, and the expression of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, by real-time polymerase chain reaction (PCR). The radiation-induced melanin pigmentation was standardized according to the doses of each radiation and evaluated by digital image analysis (Fontana-Masson). RESULTS: The primary skin culture was standardized at room temperature using DMEM medium. The doses of UVB, UVA, and VL (blue light) that induced differential melanogenesis were: 166mJ/cm2, 1.524J/cm2, and 40J/cm2. The expression of the GAPHD constitutional gene did not differ between the sample of skin processed immediately after tissue collection and the sample cultured for 72h in the standardized protocol. STUDY LIMITATIONS: This was a preliminary study that evaluated only the viability and integrity of the melanogenic system, and the effect of the radiation alone. CONCLUSIONS: The standardized model maintained viable melanocytic function for 72h at room temperature, allowing the investigation of melanogenesis induced by different forms of radiation.


Assuntos
Técnicas de Cultura de Células/normas , Luz , Melaninas/biossíntese , Melaninas/efeitos da radiação , Organoides/efeitos da radiação , Raios Ultravioleta , Adulto , Biópsia , Células Cultivadas , Expressão Gênica , Humanos , Doses de Radiação , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Nitrato de Prata , Pigmentação da Pele/efeitos da radiação , Fatores de Tempo
11.
Environ Pollut ; 256: 113484, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31677872

RESUMO

The widespread production and use of silver nanomaterials (AgNMs) in consumer and medical products have been raising environmental concerns. Once in the environment, the soil is one of the major sinks of AgNMs due to e.g. sewage sludge applications, and invertebrates are directly exposed. In this study, we investigate the potential of N-acetylcysteine (NAC) to reduce the toxic effects of Ag NM300 K (and AgNO3) on the soil invertebrate Enchytraeus crypticus. Ag NM300 K induces mortality, reproduction impairment, and avoidance. The addition of NAC to the soil showed a remarkable reduction in the toxicity of Ag, indicating that NAC can act as a detoxifying agent for terrestrial organisms exposed to Ag materials. That the reduction in toxicity likely is caused by thiol groups, was confirmed by GSH and GSSH studies. Identifying the mechanisms and hence alternatives that allow the recovery of contaminated soils is an important mitigation measure to promote environmental safety and reduce the associated risks to human health. Further, it may inform on strategies to implement in safe-by-design industry development.


Assuntos
Nanoestruturas/toxicidade , Oligoquetos/fisiologia , Prata/toxicidade , Poluentes do Solo/toxicidade , Acetilcisteína/metabolismo , Animais , Oligoquetos/efeitos dos fármacos , Reprodução/efeitos dos fármacos , Esgotos , Nitrato de Prata/toxicidade , Solo , Poluentes do Solo/análise
12.
J Chromatogr A ; 1613: 460660, 2020 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-31685247

RESUMO

Pyrethrum extract is a natural insecticide that has been used worldwide for centuries, with pyrethrins being considered active ingredients. Their purification is difficult due to their chemical structural similarity and instability to light. In the present study, a coordination complex high-speed counter-current chromatography was used to separate pyrethrins from pyrethrum extract. The two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (10:2:10:2, v/v/v/v) with 0.30 mol/L silver nitrate was selected for separation. As a result, five pyrethrins including cinerin II (31.2 mg), pyrethrin II (43.9 mg), jasmalin II (39.1 mg), pyrethrin I (32.4 mg), and jasmalin I (16.0 mg) were obtained from 400 mg crude extract in 6 h by one-step HSCCC separation, with purities over 95%. The isolated compounds were identified by MS, 1H-NMR and 13C-NMR spectroscopy. The results demonstrated that the addition of silver nitrate in the two-phase solvent system of HSCCC significantly increased the HSCCC separation factor of pyrethrins. HSCCC is a rapid method for purification of pyrenthrins from pyrethrum extract. The established method may also be applied to separate analogous compounds from natural products in which the chemical structure differs in the position or numbers of alkenes.


Assuntos
Chrysanthemum/química , Distribuição Contracorrente/métodos , Piretrinas/isolamento & purificação , Nitrato de Prata/química , Flores/química , Extratos Vegetais/química , Piretrinas/análise
13.
Ann Anat ; 227: 151431, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31634560

RESUMO

Histological analysis is a fundamental and principal method used in biological research and even for disease diagnosis. The result shows the status of cells and tissues in organs and enables us to infer the condition of the whole body. The tissue staining method known as hematoxylin and eosin staining (HE) is one of the most general methods of investigating the status of cells and tissues. Hematoxylin stains the nucleus violet and eosin stains cytosol pink. HE staining shows the unique morphologies of tissues and cells. However, after being stained with HE, tissues are very difficult to use in another histological analysis because hematoxylin is hard to remove from the sections due to its stain stability. Therefore, serial sections of the tissue are used to obtain more information through another staining, including immunohistochemistry. The adjacent tissue section is not the same as the HE-stained section, however, so the results from the adjacent sections can cause confusion or ambiguity. The present study showed that our decolorization solution can decolor the hematoxylin or iron hematoxylin stain from stained structures, including the nucleus, and the decolored section could be stained again in another staining, including immunohistochemistry. This decolorization method is very valuable, in that it can determine the accurate distribution of substances and features in cells and tissues, and thus it can improve the robustness of the resulting data.


Assuntos
Corantes/metabolismo , Corantes Fluorescentes/metabolismo , Animais , Compostos Azo/metabolismo , Ácidos Carboxílicos/química , Quelantes/química , Amarelo de Eosina-(YS)/metabolismo , Hematoxilina/metabolismo , Imuno-Histoquímica , Verde de Metila/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Microscopia de Fluorescência , Ácidos Fosfóricos/química , Nitrato de Prata/metabolismo , Trometamina/química
14.
Ultrason Sonochem ; 60: 104797, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31546086

RESUMO

Ultrasonicaion is non-chemical process where acoustic waves have been targeted to aqueous medium dispersed precursor materials. In situ synthesis of silver nanoparticles anchored in hydrogel matrix has been opted via ~20 kHz frequency assisted (bath sonication) synthesis having the ultrasonication power intensity (UPI) of ~106 J/m2. Power intensity is inversely proportional to the surface area of the clay tactoids. The hydrogel have been prepared by in situ 20 kHz assisted sonochemical destratification of laponite clay tactoids which could be terminologically stated as 'top-down method'. Silver nanoparticles (AgNPs) have been deposited in the surfaces of the porous matrix of hydrogel via 'soak and irradiate' method. Soaking of silver ions into the gel matrix is welcomed due to their efficient stabilization and fast transformation towards AgNPs. AgNPs played the key role in catalytic reduction and bactericidal activity. Moreover, the prepared hydrogel has enough robust to withstand cyclic stress, uniaxial stress and oscillatory stress which have been extensively justified by the physico-mechanical characterizations. The gel supported catalyst showed first order reaction kinetics and less time consuming period during reduction of 4-nitrophenol as a model pollutant.


Assuntos
Acústica , Antibacterianos/química , Argila , Elastômeros/química , Hidrogéis/química , Sonicação/métodos , Catálise , Cinética , Nanopartículas Metálicas/química , Nitrofenóis/química , Oxirredução , Prata/química , Nitrato de Prata/química
15.
Int J Phytoremediation ; 22(1): 40-51, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31282192

RESUMO

Silver nanoparticles (AgNPs) are among the most widely used nanomaterials, with applications in sectors as diverse as communications, energy, medicine, and agriculture. This diverse application of AgNPs increases the risk of the release of these materials into the environment and raises the potential for transfer into plants and, subsequently, the human body. To better understand the effects of NPs in agricultural systems, this study investigates plant physiological and molecular responses upon exposure to AgNPs in comparison to silver nitrate (AgNO3). Tomato seedlings (Lycopersison esculentum) were exposed to 10, 20, or 30 mg/L silver (Ag), AgNO3, or AgNPs in hydroponic media for 7 days. A number of endpoints were measured, including plant growth, photosynthetic pigments, oxidative and antioxidant responses. The results showed 2-7 times lower growth rate in plants exposed to silver compared to the control. H2O2 and malondialdehyde as oxidative stress indicators were, respectively, 1.7 and 4 times higher in plants exposed to all forms of silver compared to the control. The antioxidative responses increased significantly in plants exposed to Ag and AgNPs compared to the control. However, plants exposed to AgNO3 showed up to 50% lower enzymatic antioxidant activity. At the molecular level, the expression of genes involved in defense responses, including ethylene-inducing xylanase (EIX), peroxidase 51 (POX), and phenylalanine ammonia lyase, were significantly upregulated upon exposure to silver. The molecular and physiological data showed exposure to all forms of silver resulted in oxidative stress and exposure to AgNPs induced antioxidative and defense responses. However, exposure to AgNO3 resulted in phytotoxicity and failure in antioxidative responses. It indicates the higher reactivity and phytotoxicity of the ionic form of silver compared to NPs. The findings of this study add important information to efforts in attempting to characterize the exposure and risk associated with the release of nanomaterials in the environment.


Assuntos
Lycopersicon esculentum , Nanopartículas Metálicas , Biodegradação Ambiental , Peróxido de Hidrogênio , Prata , Nitrato de Prata
16.
Chemosphere ; 238: 124576, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31421462

RESUMO

This study assesses and compares the influence of silver nanoparticles (AgNPs) and silver nitrate (AgNO3) on the fatty acid composition, pigments, and growth indices of Chlorella vulgaris. Toxicity testing was carried at the estimated and/or above predicted environmental concentrations of AgNPs and AgNO3. AgNO3 treatments impaired the population growth of C. vulgaris about 2-183 times more than the respective AgNPs ones. The pigments displayed a concentration-dependent decrease in response to both forms of silver; however, AgNO3 displayed higher severity to the pigments than AgNPs. In exposure to 10 µg L-1 AgNO3, the contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid, respectively, demonstrated a reduction of about 5, 3, 4, and 4 times when compared with the same respective concentration of AgNPs. Total amounts of saturated (∑SFA), monounsaturated (∑MUFA), and polyunsaturated (∑PUFA) fatty acids as well as the ratio of unsaturated to saturated ones (Unsat./Sat.) displayed somewhat similar-concentration responses. ∑SFA exhibited a hormesis response, and ∑MUFA, ∑PUFA, and Unsat./Sat. did a decreasing trend with increasing concentration of AgNPs and AgNO3. Myristoleic acid, nervonic acid, and eicosadienoic acid revealed the highest sensitivity. Pearson analysis illustrated the highest correlation among myristoleic acid, eicosenoic acid, and nervonic acid as well as among palmitic acid, stearic acid, palmitoleic acid, and oleic acid. Taken together, AgNPs and the released ions could disrupt physiological health state of microalgae through perturbation in the fatty acid composition (especially MUFAs and PUFAs) and other macromolecules. These types of bioperturbations could change the good health state of aquatic ecosystems.


Assuntos
Chlorella vulgaris/crescimento & desenvolvimento , Poluentes Ambientais/toxicidade , Ácidos Graxos/metabolismo , Nanopartículas Metálicas/toxicidade , Nitrato de Prata/toxicidade , Prata/toxicidade , Carotenoides/metabolismo , Chlorella vulgaris/metabolismo , Clorofila/metabolismo , Clorofila A/metabolismo , Ecossistema , Ecotoxicologia , Ácidos Graxos Monoinsaturados/metabolismo , Microalgas/efeitos dos fármacos , Testes de Toxicidade
17.
Med Mycol J ; 60(4): 85-89, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31787731

RESUMO

BACKGROUND: The rate of aspergillosis has decreased due to improvements in therapy. The rate of mucormycosis, however, has gradually increased in recent years. Both aspergillosis and mucormycosis produce histologically similar hyphae, pointing to the need for an objective tool to distinguish between them. METHODS: Three aspergillosis cases and three mucormycosis cases were selected from autopsy cases in our hospital. Representative histological images were captured and hyphal angles in extravascular and intravascular lesions were calculated. RESULTS: For both extravascular and intravascular lesions, the average hyphal angle of aspergillosis was acute, and the standard deviation was less than that of mucormycosis. In aspergillosis, the average hyphal angle for extravascular lesions was acute, and the standard deviation was less than that for intravascular lesions. However, for mucormycosis, there was no significant difference in both the average and standard deviation of the hyphal angles. CONCLUSION: Surgical pathologists should carefully examine the histological characteristics of the fungus to correctly identify specimens and be able to administer proper therapies.


Assuntos
Aspergilose/microbiologia , Aspergillus , Hifas , Técnicas Microbiológicas/métodos , Mucorales , Mucormicose/microbiologia , Aspergilose/diagnóstico , Aspergillus/isolamento & purificação , Vasos Sanguíneos/microbiologia , Diagnóstico Diferencial , Humanos , Mucorales/isolamento & purificação , Mucormicose/diagnóstico , Nitrato de Prata , Coloração e Rotulagem/métodos
18.
IET Nanobiotechnol ; 13(9): 896-904, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31811757

RESUMO

The research work was arranged to check the role of AgNPs and silver ions on callus cells of sugarcane (Saccharum spp. cv CP-77,400). AgNPs were synthesized chemically and characterized by UV-Vis spectra, XRD and SEM. AgNPs and silver ions were applied in various concentrations (0, 20, 40, 60 ppm) to sugarcane calli and the induced stress was characterized by studying various morphological and biochemical parameters. AgNPs and silver ions treatments produced high levels of malondialdehyde, proline, proteins, TP and TF contents. Similarly, CAT, SOD and POX activity was also significant in both treatments. The lower concentration of AgNPs and silver ions (20 ppm) provided maximum intracellular GSH level. This work mainly showed effects of AgNPs and silver ions on sugarcane calli in terms of morphological aberrations and cell membrane damage due to severe oxidative stress and production of enhanced levels of enzymatic and non-enzymatic antioxidants as self-defence to tolerate oxidative stress by scavenging reactive oxygen species. These preliminary findings will provide the way to study ecotoxicity mechanism of the metal ions and NPs in medicine industry and in vitro toxicity research. Furthermore, silver ions alone and their chemically synthesised AgNPs can be used for various biomedical applications in future.


Assuntos
Nanopartículas Metálicas/química , Saccharum/metabolismo , Nitrato de Prata/química , Prata/química , Microscopia Eletrônica de Varredura , Estresse Oxidativo , Espectrofotometria Ultravioleta , Difração de Raios X
19.
BMC Res Notes ; 12(1): 773, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31775864

RESUMO

OBJECTIVE: Silver nanoparticles (AgNPs) can be difficult or expensive to obtain or synthesize for laboratories in resource-limited facilities. The purpose of this work was to optimize a synthesis method for a fast, facile, and cost-effective synthesis of AgNPs with antimicrobial activity, which can be readily implemented in non-specialized facilities and laboratories. RESULTS: The optimized method uses a rather simple and rapid chemical reduction process that involves the addition of a polyvinylpyrrolidone solution to a warmed silver nitrate solution under constant vigorous stirring, immediately followed by the addition of sodium borohydride. The total synthesis time is less than 15 min. The obtained AgNPs exhibit an aspect ratio close to 1, with an average size of 6.18 ± 5 nm. AgNPs displayed potent antimicrobial activity, with Minimal Inhibitory Concentration values of ≤ 4 µg mL-1 for Staphylococcus aureus and ≤ 2 µg mL-1 for Candida albicans. The resulting method is robust and highly reproducible, as demonstrated by the characterization of AgNPs from different rounds of syntheses and their antimicrobial activity.


Assuntos
Antibacterianos/síntese química , Antifúngicos/síntese química , Nanopartículas Metálicas/química , Prata/química , Antibacterianos/farmacologia , Antifúngicos/farmacologia , Boroidretos/química , Candida albicans/efeitos dos fármacos , Técnicas de Química Sintética , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Povidona/química , Nitrato de Prata/química , Staphylococcus aureus/efeitos dos fármacos
20.
BMC Genomics ; 20(1): 811, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31694528

RESUMO

BACKGROUND: Drought stress is a major limiting factor of soybean [Glycine max (L.) Merr.] production around the world. Soybean plants can ameliorate this stress with improved water-saving, sustained N2 fixation during water deficits, and/or limited leaf hydraulic conductance. In this study, carbon isotope composition (δ13C), which can relate to variation in water-saving capability, was measured. Additionally, nitrogen isotope composition (δ15N) and nitrogen concentration that relate to nitrogen fixation were evaluated. Decrease in transpiration rate (DTR) of de-rooted soybean shoots in a silver nitrate (AgNO3) solution compared to deionized water under high vapor pressure deficit (VPD) conditions was used as a surrogate measurement for limited leaf hydraulic conductance. A panel of over 200 genetically diverse soybean accessions genotyped with the SoySNP50K iSelect BeadChips was evaluated for the carbon and nitrogen related traits in two field environments (Athens, GA in 2015 and 2016) and for transpiration response to AgNO3 in a growth chamber. A multiple loci linear mixed model was implemented in FarmCPU to perform genome-wide association analyses for these traits. RESULTS: Thirty two, 23, 26, and nine loci for δ13C, δ15N, nitrogen concentration, and transpiration response to AgNO3, respectively, were significantly associated with these traits. Candidate genes that relate to drought stress tolerance enhancement or response were identified near certain loci that could be targets for improving and understanding these traits. Soybean accessions with favorable breeding values were also identified. Low correlations were observed between many of the traits and the genetic loci associated with each trait were largely unique, indicating that these drought tolerance related traits are governed by different genetic loci. CONCLUSIONS: The genomic regions and germplasm identified in this study can be used by breeders to understand the genetic architecture for these traits and to improve soybean drought tolerance. Phenotyping resources needed, trait heritability, and relationship to the target environment should be considered before deciding which of these traits to ultimately employ in a specific breeding program. Potential marker-assisted selection efforts could focus on loci which explain the greatest amount of phenotypic variation for each trait, but may be challenging due to the quantitative nature of these traits.


Assuntos
Carbono/metabolismo , Estudo de Associação Genômica Ampla , Nitrogênio/metabolismo , Folhas de Planta/metabolismo , Soja/genética , Soja/metabolismo , Aquaporinas/antagonistas & inibidores , Perfilação da Expressão Gênica , Loci Gênicos/genética , Nitrato de Prata/farmacologia
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