Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.496
Filtrar
1.
Chemosphere ; 254: 126866, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32348923

RESUMO

Hydrochar, the product of hydrothermal carbonization of biomass, is a sustainable alternative to other carbonaceous environmental sorbents. However, its use has been limited due to its low surface area. A one-pot biomass/metal salt co-hydrothermal synthesis method might improve its sorptive properties while retaining its efficient production characteristic. Thus, bamboo sawdust and zinc chloride (ZnCl2) were combined in a hydrothermal reactor (200 °C, 7 h) for preparing modified hydrochar. Compared to the non-modified hydrochar, the hydrochar produced with the addition of ZnCl2 during hydrothermal treatment was more fully carbonized (C content increased from 54% to 64%), of higher surface area after acid washing (30 versus 1.7 m2 g-1), and enriched in O-containing functional groups and of greater aromaticity (according to FTIR and XRD analysis). Because of these improved properties, Methylene blue adsorption capacity of the modified hydrochar increased by nearly 90% and by 257% after it was rinsed with acid. This study highlights the potential of this one-pot co-hydrothermal treatment of biomass in presence of metal salt to provide a simple and effective hydrochar with properties suitable for environmental remediation and water treatment.


Assuntos
Cloretos/química , Purificação da Água/métodos , Compostos de Zinco/química , Adsorção , Biomassa , Carbono , Azul de Metileno , Temperatura
2.
Chemosphere ; 254: 126868, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32348924

RESUMO

The increasing application of Quantum Dots (QDs) is cause of concern for the potential negative effects for the ecosystem, especially in soils that may act as a sink. In this study, soil leaching experiments were performed in quartz sand packed columns to investigate the behavior of core-shell CdSe/ZnS QDs coated with either small ligands (TGA-QDs) or more complex polymers (POAMA-QDs). Fluorescence emission was compared to mass spectrometric measurements to assess the nanoparticles (NPs) state in both the leachate (transported species) and porous media (deposited amounts). Although both QDs were strongly retained in the column, large differences were observed depending on their capping ligand stability. Specifically, for TGA-QDs elution was negligible and the retained fraction accumulated in the top-columns. Furthermore, 74% of the NPs were degraded and 38% of the Se was found in the leachate in non-NPs state. Conversely, POAMA-QDs were recovered to a larger extent (78.1%), and displayed a higher transport along the soil profile. Further experiments with altered NPs showed that homo-aggregation of the QDs prior injection determined a reduced mobility but no significant changes in their stability. Eventually, ageing of the NPs in the column (15 days) caused the disruption of up to 92% of the original QDs and the immobilization of NPs and metals. These results indicate that QDs will accumulate in top-soils, where transformations phenomena will determine the overall transport, persistency and degradation of these chemicals. Once accumulated, they may act as a source for potentially toxic Cd and Se metal species displaying enhanced mobility.


Assuntos
Pontos Quânticos , Poluentes do Solo/análise , Compostos de Cádmio/química , Ecossistema , Ligantes , Nanopartículas , Compostos de Selênio/química , Solo/química , Sulfetos , Compostos de Zinco
3.
BMC Public Health ; 20(1): 303, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32156268

RESUMO

BACKGROUND: Acute pesticide poisoning (APP) is reported to affect community health worldwide but its burden in Tanzania is unknown particularly in women. This study examines APP involving adult females and adolescent girls 10 to 19 years in 3 regions of Tanzania which are famous for coffee and vegetable production. METHODS: Over the period of 12 months, health facility-based surveillance for cases of APP was implemented in 10 Tanzanian healthcare facilities in 2006. RESULTS: The study identified 108 APP cases of whom 31 (28.7%) occurred amongst adolescent girls. Suicide was the leading poisoning circumstances (60.2%) and the most vulnerable women were 20-29 years old who comprised 38.4% of all cases with suicide as circumstance. Organophosphates (OPs), zinc phosphide, paraquat and endosulfan were common amongst known reported poisoning agents. The annual APP incidence, mortality and Case Fatality Rate for women were 5.1/100,000, 0.2/100,000 and 3.7/100, respectively. CONCLUSION: APP amongst women in Tanzania is common and this call for diverse preventive interventions to reduce poisoning incidents.


Assuntos
Praguicidas/envenenamento , Adolescente , Adulto , Criança , Endossulfano/envenenamento , Feminino , Humanos , Incidência , Intoxicação por Organofosfatos/epidemiologia , Paraquat/envenenamento , Fosfinas/envenenamento , Suicídio/estatística & dados numéricos , Tanzânia/epidemiologia , Adulto Jovem , Compostos de Zinco/envenenamento
4.
PLoS One ; 15(3): e0229527, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32126098

RESUMO

Labeling substrates or products are paramount in determining enzymatic kinetic parameters. Several options are available; many laboratories use either radioactive or fluorescent labeling because of their high sensitivity. However, those methods have their own drawbacks such as half-life decay, expensive and hazardous. Here, we propose a novel, simple, economical and fast alternative to substrate labeling for studying the kinetics of nucleic acids: post-migration gel staining with SYBR Gold. Cleavage rates similar to the ones reported in the literature for the I-R3 DNA-cleaving DNA enzyme in the presence of zinc chloride are an indication of the quality of the new method. Moreover, the activity of the hammerhead ribozyme was also monitored by our method to illustrate its versatility. This labeling-free method has several advantages such as its ease of use as well as cost effective and versatility with both non-structured and structured RNAs or DNAs.


Assuntos
Corantes Fluorescentes , Ácidos Nucleicos/análise , Compostos Orgânicos , 2-Aminopurina/química , Sítios de Ligação , Cloretos/metabolismo , DNA/análise , DNA/genética , DNA Catalítico/metabolismo , Cinética , Conformação de Ácido Nucleico , Ácidos Nucleicos/genética , RNA Catalítico/metabolismo , Espectrometria de Fluorescência , Coloração e Rotulagem/métodos , Especificidade por Substrato , Compostos de Zinco/metabolismo
5.
Environ Pollut ; 260: 114045, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32045968

RESUMO

The increasing release of metallic nanoparticles (NPs) or their sulfidized forms into soils have raised concerns about their potential risks to soil ecosystems. Hence, there is a need for novel strategies to remediate metallic NPs pollution in soils. In this study, to explore the feasibility of using earthworm Eisenia fetida to manage soils contaminated with metallic NPs, we simultaneously investigated the chronic soil toxicities of ZnO NPs and ZnS NPs to E. fetida, and the effects of E. fetida on Zn extractability in soils amended with ZnO NPs and ZnS NPs. After a 28 d exposure, survival rate and weight loss of earthworms were not impacted by either ZnO NPs or ZnS NPs at a concentration of 400 mg Zn per kg soil. Further, while ZnO NPs activated earthworm antioxidative system, ZnS NPs resulted in significant alleviation of oxidative damage in earthworm. The presence of earthworms significantly decreased the bioavailability of Zn in ZnO NPs contaminated soil, whereas significantly increased the bioavailability of Zn in ZnS NPs contaminated soil. These findings implied that the earthworm E. fetida could play an important role in altering the mobilization of metals originating from metallic NPs in soils, which may further aid in the development of a method for the treatment of metallic NPs pollution in soils.


Assuntos
Nanopartículas , Oligoquetos , Poluentes do Solo , Óxido de Zinco , Animais , Disponibilidade Biológica , Ecossistema , Solo , Sulfetos , Zinco , Compostos de Zinco
6.
Chemosphere ; 249: 126227, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32087456

RESUMO

Efficient lead removal from metal-containing wastewater, such as acid mine drainage (AMD), is an important step in environmental purification and secondary resources recovery. In this paper, a novel approach by mechanochemically activating CaCO3 through simply wet ball milling in metal-containing solution was developed, where selective Pb2+ precipitation in the form of PbCO3 was achieved based on its reaction with the CO32- from the activated CaCO3. By such milling operation, the removal efficiency of Pb2+ from aqueous solution could reach over 99%, while more than 99% Zn2+ (as well as Mn, Ni and Cd) was remaining in the solutions, demonstrating the feasibility and high effectiveness of precipitating Pb2+ and serving the purpose of recovering other metals without Pb impurity. The solubility differences between Pb carbonate and other carbonates of Zn, Mn, Ni or Cd were understood to be the main pathway and using CaCO3 would offer an easy operation and environmental friendly process to purify the metals-containing wastewater by precipitating Pb, compared with the difficulties when using alkaline neutralization to treat them. In addition, basic zinc carbonate (a zinc-containing ore waste) as an alternative precipitant to CaCO3 in the separation process was also confirmed to increase the zinc recovery in the solution while maintaining high Pb2+ removal efficiency.


Assuntos
Carbonato de Cálcio/química , Chumbo/química , Eliminação de Resíduos Líquidos/métodos , Carbonatos , Química Verde , Metais Pesados/análise , Mineração , Águas Residuárias , Água , Purificação da Água , Zinco/análise , Zinco/química , Compostos de Zinco
7.
J Environ Sci (China) ; 90: 216-233, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32081318

RESUMO

Widespread usage of engineered metallic quantum dots (QDs) within consumer products has evoked a need to assess their fate within environmental systems. QDs are mixed-metal nanocrystals that often include Cd2+ which poses a health risk as a nanocrystal or when leached into water. The goal of this work is to study the long-term metal cation leaching behavior and the factors affecting the dissolution processes of mercaptopropionic acid (MPA) capped CdSe/ZnS QDs in aphotic conditions. QD suspensions were prepared in different water conditions, and release of Zn2+ and Cd2+ cations were monitored over time by size exclusion chromatography-inductively coupled plasma-mass spectrometry. In most conditions with dissolved O2 present, the ZnS shell degraded fairly rapidly over ~1 week, while some of the CdSe core remained up to 80 days. Additional MPA, Zn2+, and Cd2+ temporarily delayed dissolution, indicating a moderate role for capping agent detachment and mineral solubility. The presence of H2O2 and the ligand ethylenediaminetetraacetate accelerated dissolution, while NOM had no kinetic effect. No dissolution of CdSe core was observed when O2 was absent or when QDs formed aggregates at higher concentrations with O2 present. The shrinking particle model with product layer diffusion control best describes Zn2+ and Cd2+ dissolution kinetics. The longevity of QDs in their nanocrystal form appears to be partly controlled by environmental conditions, with anoxic, aphotic environments preserving the core mineral phase, and oxidants or complexing ligands promoting shell and core mineral dissolution.


Assuntos
Compostos de Cádmio , Pontos Quânticos , Compostos de Selênio , Água/química , Peróxido de Hidrogênio , Cinética , Solubilidade , Sulfetos , Compostos de Zinco/química
8.
Anal Bioanal Chem ; 412(8): 1893-1899, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32016568

RESUMO

Superoxide dismutase (SOD), also known as liver protein, is a substance widely distributed in various biological cells. It has the function of catalyzing the disproportionation reaction of superoxide free radicals. SOD can form an antioxidant chain together with peroxidase, catalase, and other substances in the body of organisms, and thus, is one of the indispensable important substances in the body of organisms. In this work, we provided a simple and fast visual electrochemiluminescence (ECL) sensor for SOD detection. CuInZnS quantum dots (QDs) worked as the ECL luminophore with hydrogen peroxide as co-reactant. In the sensing process, SOD and CuInZnS QDs on a glassy carbon electrode (GCE) competed with each other for hydrogen peroxide to produce superoxide during electrochemical luminescence, thus quenching the ECL signal of CuInZnS QDs. The proposed sensor can quantify SOD with a limit of detection (LOD) of 0.03 µg/mL. In addition, the change in the CuInZnS QDs ECL signal was easily observed with a smartphone camera. The results indicated that this sensor could effectively work in the detection of SOD in human blood. Graphical abstract.


Assuntos
Cobre/química , Técnicas Eletroquímicas/métodos , Índio/química , Luminescência , Pontos Quânticos/química , Sulfetos/química , Superóxido Dismutase/análise , Compostos de Zinco/química , Técnicas Biossensoriais , Limite de Detecção , Reprodutibilidade dos Testes
9.
J Environ Manage ; 260: 110145, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32090837

RESUMO

A comparative photocatalytic degradation of 2-chlorophenol (2CP) in aqueous solution was investigated using pristine and Ag-doped semiconductor photocatalysts obtained from TiO2, ZnO and ZnS. Varying percentages (1, 3 and 5%) of Ag nanoparticles were doped on the semiconductor photocatalysts via the sol-gel method. The pristine and Ag-doped photocatalysts were characterized using UV-Vis diffuse reflectance spectroscopy, photo-luminescence spectroscopy, X-Ray diffractometry, Fourier transform infrared spectroscopy and transmission electron microscopy; and these techniques confirmed the successful syntheses of the pristine and Ag-doped species. The photocatalytic activities of all species for the degradation of 2CP were carried in photo-reactor using UV irradiation intensity of 1.4 mW/cm2 for 150 min; and the effects of various operating parameters (such as catalyst loading, pH and 2CP initial concentrations) were studied. The results showed enhanced 2CP degradation in the Ag-doped species in comparison to the pristine species while alkaline pH region was most suitable for 2CP degradation especially at low concentration. Lower loadings of the photocatalysts were usually more effective for the 2CP degradation and the degradation trend in the TiO2 and ZnS species was 5% Ag-doped >3% Ag-doped >1% Ag-doped > Pristine, while it was 1% Ag-doped >3% Ag-doped >5% Ag-doped > Pristine in the ZnO. Thus, although the Ag doping enhanced 2CP by all semiconductor photocatalysts, the Ag-doped TiO2 was more effective than the ZnO and ZnS species.


Assuntos
Nanopartículas Metálicas , Óxido de Zinco , Catálise , Clorofenóis , Prata , Sulfetos , Compostos de Zinco
10.
Chemosphere ; 246: 125629, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927360

RESUMO

In this study, a metabolomic analysis was used to reveal the neurotoxicity of the CdTe/ZnS QDs via microglia polarization. A gas chromatography-mass spectrometer (GC-MS) was applied to uncover the metabonomic changes in microglia (BV-2 cell line) after exposure to 1.25 µM CdTe/ZnS QDs. 11 annotated metabolic pathways (KEGG database) were significantly changed in all exposed groups (3 h, 6 h, 12 h), 3 of them were related to glucose metabolism. The results of the Seahorse XFe96 Analyzer indicated that the CdTe/ZnS QDs increased the glycolysis level of microglia by 86% and inhibited the aerobic respiration level by 54% in a non-hypoxic environment. In vivo study, 3 h after the injection of CdTe/ZnS QDs (2.5 mM) through the tail vein in mice, the concentration of the CdTe/ZnS QDs in hippocampus reached the peak (1.25 µM). The polarization level of microglia (Iba-1 immunofluorescence) increased 2.7 times. In vitro study, the levels of the extracellular TNF-α, IL-1ß and NO of BV-2 cells were all increased significantly after a 6 h or 12 h exposure. According to the results of the Cell Counting Kit-8, after a 6 h or 12 h exposure to the CdTe/ZnS QDs, the exposed microglia could significantly decrease the number of neurons (HT-22 cell line). This study proved that CdTe/ZnS QDs could polarize microglia in the brain and cause secondary inflammatory damage to neurons. There are potential risks in the application of the CdTe/ZnS QDs in brain tissue imaging.


Assuntos
Metabolômica/métodos , Microglia/efeitos dos fármacos , Pontos Quânticos/toxicidade , Animais , Compostos de Cádmio , Polaridade Celular/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Glicólise/efeitos dos fármacos , Hipocampo/patologia , Camundongos , Síndromes Neurotóxicas/etiologia , Pontos Quânticos/química , Sulfetos , Telúrio , Compostos de Zinco
11.
Anal Bioanal Chem ; 412(7): 1663-1673, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31993725

RESUMO

A novel room temperature phosphorescence chemosensor probe has been successfully developed and applied to the selective detection and quantification of inorganic arsenic (As(III) plus As(V)) in fish samples. The prepared material (IIP@ZnS:Mn QDs) was based on Mn-doped ZnS quantum dots coated with (3-aminopropyl) triethoxysilane and an As(III) ionic imprinted polymer. The novel use of vinyl imidazole as a complexing reagent when synthesizing the ionic imprinted polymer guarantees that both inorganic arsenic species (As(III) and As(V)) can interact with the recognition cavities in the ionic imprinted polymer. After characterization, several studies were performed to enhance the interaction between the targets (As(III) and As(V) ions) and the IIP@ZnS:Mn QDs nanoparticles. The optimization and validation process showed that the composite material offers high selectivity (high imprinting factor) for inorganic arsenic species. The limit of quantification for total inorganic As was 29.6 µg kg-1, value lower than the EU/EC regulation limits proposed for other foodstuffs than fish, such as rice. The proposed method is therefore simple, requires short analysis times and offers good sensitivity, precision (inter-day relative standard deviations lower than 10%), and quantitative analytical recoveries. The method has been successfully applied to assess total inorganic arsenic in several fishery products, showing good agreement with the total inorganic arsenic concentration (As(III) plus As(V)) found after applying other advanced and expensive methods such those based on high-performance liquid chromatography hyphenated to inductively coupled plasma-mass spectrometry. Graphical abstract.


Assuntos
Arsênico/análise , Peixes , Manganês/química , Impressão Molecular/métodos , Polímeros/química , Pontos Quânticos/química , Dióxido de Silício/química , Sulfetos/química , Compostos de Zinco/química , Animais , Cromatografia Líquida de Alta Pressão/métodos , Concentração de Íons de Hidrogênio , Limite de Detecção , Espectrometria de Massas/métodos , Reprodutibilidade dos Testes , Propriedades de Superfície
12.
Nanotoxicology ; 14(3): 372-387, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31909648

RESUMO

The annual increase in the production and the use of engineering quantum dots (QDs) have led to concern about exposure and safety of QDs. To resolve the risk of Cd release from QDs, a series of Cd-free QDs, represented by CuInS2/ZnS QDs, has been developed in recent years. However, the toxicological profile of CuInS2/ZnS QDs has not been fully elucidated, especially, their immunotoxicity. Here, we performed a detailed in vitro cytotoxicity study on PEGylated CuInS2/ZnS QDs using the DC2.4 cell line and investigated their in vivo immunotoxicity using BALB/c mice. In vitro experiments showed that CuInS2/ZnS QDs were taken up by cells, promoted cell viability, enhanced release of tumor necrosis factor-α, and decreased the level of interleukin (IL)-6 in response to lipopolysaccharide stimulation. More than 5000 genes at the transcriptome level were observed by high-throughput RNA sequencing after CuInS2/ZnS QD exposure. In vivo study showed that CuInS2/ZnS QDs increased the levels of IL-4 on day 1 and enhanced the levels of IL-10 and IL-13 on day 28 in mice. There was no obvious difference in the number of spleen-derived lymphocytes, organic index, hematology and immune organ histology on days 1 and 28 after treatment. These findings demonstrated that PEGylated CuInS2/ZnS QDs disturbed the function of DC2.4 immune cells in vitro, but caused no obvious toxicity to immune system in vivo, suggesting that PEGylated CuInS2/ZnS QDs are biocompatible and have potential for bioapplication in the future.


Assuntos
Cobre/toxicidade , Sistema Imunitário/efeitos dos fármacos , Índio/toxicidade , Polietilenoglicóis/química , Pontos Quânticos/toxicidade , Sulfetos/toxicidade , Compostos de Zinco/toxicidade , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/imunologia , Feminino , Sistema Imunitário/imunologia , Interleucina-6/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Pontos Quânticos/química , Baço/efeitos dos fármacos , Baço/imunologia , Timo/efeitos dos fármacos , Timo/imunologia , Transcriptoma/efeitos dos fármacos , Fator de Necrose Tumoral alfa/metabolismo
13.
J Environ Sci (China) ; 89: 156-166, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31892388

RESUMO

Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes. To develop value in the exploitation of sphalerite, samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties. X-ray diffraction (XRD) and electron probe micro analysis (EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions. The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight, Mn from 0.004% to 4.868%, Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%. As Fe became more abundant, the color of natural sphalerite darkened, becoming almost black; and higher Fe content was associated with stronger visible light absorption. Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content. Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity. Specifically, the degradation of Methyl Orange (30 mg/L) attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with 4.262% Fe and 1.576% Cd. Overall, the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes, while substitution by Cd was observed to have a greater effect on the photocatalytic properties. These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite.


Assuntos
Processos Fotoquímicos , Sulfetos , Compostos de Zinco , Catálise , China
14.
Environ Pollut ; 256: 113417, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31662269

RESUMO

A facile method was developed to fabricate porous tube-like ZnS by sulfurizing rod-like ZIF-L with thioacetamide (TAA) at different durations and the formation mechanism of the porous tube-like ZnS was discussed in detail. The series of sulfide products (ZS-X) were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance spectroscopy (SSNMR), transmission electron microscopy (TEM), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS). The photocatalytic performances of ZS-X toward Cr(VI) reduction and organic pollutant degradation were explored. It was discovered that ZS-3 (porous tube-like ZnS) exhibited excellent activities under UV light and displayed good reusability and stability after several experimental cycles. In addition, Cr(VI) reduction and organic pollutant degradation were investigated under different pH values and existence of different foreign ions. The photocatalytic activities of ZS-3 were tested toward the matrix of Cr(VI) and reactive red X-3B. The mechanism was proposed and verified by both electrochemical analysis and electron spin resonance (ESR) measurement.


Assuntos
Cromo/química , Poluentes Ambientais/química , Catálise , Poluentes Ambientais/análise , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Sulfetos , Difração de Raios X , Compostos de Zinco
15.
Bioelectrochemistry ; 132: 107434, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31821901

RESUMO

In this study, a novel signal-amplified immunosensor was designed by using a microwave-assisted self-assembly method to synthesize ZnFe2O4-Ag/rGO nanocomposites. The conductivity of ZnFe2O4-rGO nanocomposites was significantly improved due to the effective inhibition of rGO accumulation by the insertion of ZnFe2O4 and Ag nanoparticles (NPs) into graphene sheets. Excellent sensitivity and reproducibility were achieved through the microwave-assisted preparation of ZnFe2O4-Ag/rGO nanocomposites as a substrate, with the Ag NPs enhancing the signal because of the effective conductive matrix. The layer assembly process of the immunosensor was verified by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimal conditions, the fabricated immunosensor showed good linearity over a wide concentration range from 1 pg mL-1 to 200 ng mL-1 with a low detection limit of 0.98 pg mL-1, and exhibited excellent specificity, good stability, and reproducibility. These qualities can contribute to the successful application of a label-free immunosensor in the detection of AFP in human serum.


Assuntos
Compostos Férricos/química , Grafite/química , Nanopartículas Metálicas/química , Micro-Ondas , Prata/química , Compostos de Zinco/química , alfa-Fetoproteínas/análise , Humanos , Limite de Detecção
16.
Ecotoxicol Environ Saf ; 189: 109886, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31759746

RESUMO

Chlorpyrifos (CP) is an organophosphorus pesticide used to control pests in agriculture. Brilliant green (BG) is a cationic dye widely used in textile and dyeing industry. However, the presence of pollutants in the aquatic environment has harmful effects on the environment and humans. Photocatalytic degradation can be appropriate method for water purification. Therefore, the Fe3O4/CdS-ZnS magnetic nanocomposite was synthesized and characterized by Brunauer-Emmett-Teller (BET) surface area analysis, Energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), UV-Vis-diffuse reflectance spectroscopy (DRS), and field emission scanning electron microscopy (FESEM) analyses and was used to degrade pollutants such as chlorpyrifos pesticide and brilliant green dye under visible light with source 300 W. Parameters that may be effective on photocatalytic degradation include pH, photocatalyst amount, contaminant concentration, photocatalyst and contaminant contact temperature and duration, light intensity as well as distance of light source from the reaction vessel. In the present study, the parameters that have the most influence on the degradation process were experimentally optimized, including pH, photocatalyst amount, photocatalyst reuse, and initial concentration. The study of the photocatalytic degradation rate of chlorpyrifos and brilliant green in optimal conditions (pH = 7, the concentration of pollutants = 10 ppm, volume of pollutants = 5 mL, and photocatalyst amounts for CP and BG were 0.0100 and 0.0015 g respectively) was obtained by Langmuir-Hinshelwood model. According to this model, the kapp value for CP and BG were respectively 0.0315 and 0.0119 min-1 respectively. It has been concluded that the composition of CdS and ZnS caused inhibition of the recombination of photogenerated charge carriers, leading to high catalytic efficiency. Based on the results, the synthesized nanocatalyst showed that it has the ability to photocatalytic degradation of chlorpyrifos and brilliant green in aqueous solutions.


Assuntos
Clorpirifos/química , Praguicidas/química , Compostos de Amônio Quaternário/química , Catálise , Corantes/química , Microscopia Eletrônica de Varredura , Modelos Químicos , Nanocompostos/química , Sulfetos , Água , Purificação da Água , Difração de Raios X , Compostos de Zinco
17.
Mater Sci Eng C Mater Biol Appl ; 106: 110181, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753367

RESUMO

I-III-VI chalcopyrite ternary quantum dots have emerged as a good alternative over the conventional II-VI and IV-VI chalcogenide binary QDs that usually consist of heavy metals such as Cd and Pb which has limited their bioapplications. Among the chalcopyrite QDs, AgInSe2 QDs has been the least developed due to the imbalanced cation reactivity, unwanted impurities, broad size distribution and resultant large particle sizes. In addition, the cell viability of these QDs still needs to be investigated on different cell lines both normal and cancerous ones. Herein, large-scale synthesis of water-soluble thioglycolic acid (TGA) capped and gelatin-stabilized AgInSe2 (AISe) core and AgInSe2/ZnSe (AISe/ZnSe) core/shell QDs in the absence of an inert atmosphere and their cell viability against different cell lines are reported. The optical and structural characteristics of the as-synthesized QDs were investigated by UV-visible (vis) absorption, photoluminescence (PL) and Fourier-transmission infrared (FTIR) spectroscopies, dynamic light scattering (DLS), X-ray diffraction (XRD), and high-resolution transmission electron microscope (HRTEM) techniques. Growth of ZnSe shell on the core AISe resulted in the blue shifting of the emission maximum position with the increased PL intensity. The QDs are small and spherical in shape with an average particle diameter of 2.8 nm and 3.2 nm for AISe and AISe/ZnSe QDs respectively. The in vitro cell viability assay revealed that the as-synthesized AISe/ZnSe QDs are not toxic towards cancerous (HeLa -cervical cancer and A549-lung cancer) and normal (BHK21 -Kidney) cell lines.


Assuntos
Pontos Quânticos/química , Tioglicolatos/química , Água/química , Sobrevivência Celular/fisiologia , Difusão Dinâmica da Luz , Humanos , Compostos de Selênio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , Compostos de Zinco/química
18.
Ecotoxicol Environ Saf ; 190: 110104, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31884326

RESUMO

Describing the mechanisms of zinc (Zn) accumulation in plants is essential to counteract the effects of excessive Zn uptake in crops grown in contaminated soils. Increasing evidence suggests that there is a positive correlation between nitrate supply and Zn accumulation in plants. However, the role of the primary nitrate transporter NRT1.1 in Zn accumulation in plants remains unknown. In this study, a Zn stress-induced increase in nitrate uptake and an increase in NRT1.1 protein levels in wild-type (Col-0) Arabidopsis plants were measured using microelectrode ion flux and green fluorescent protein (GFP)/ß-glucuronidase (GUS) staining, respectively. Both agar and hydroponic cultures showed that mutants lacking the NRT1.1 function in nrt1.1 and chl1-5 (chlorate resistant 1) exhibited lower Zn levels in the roots and shoots of Zn-stressed plants than the wild-type. A lack of NRT1.1 activity also alleviated Zn-induced photosynthetic damage and growth inhibition in plants. Further, we used a rotation system with synchronous or asynchronous uptakes of nitrate and Zn to demonstrate differences in Zn levels between the Col-0 and nrt1.1/chl1-5 mutants. Significantly lower difference in Zn levels were noted in the nitrate/Zn asynchronous treatment than in the nitrate/Zn synchronous treatment. From these results, it can be concluded that NRT1.1 modulates Zn accumulation in plants via a nitrate-dependent pathway.


Assuntos
Proteínas de Transporte de Ânions/metabolismo , Arabidopsis/metabolismo , Zinco/metabolismo , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Transporte de Íons , Nitratos , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Compostos de Zinco
19.
Colloids Surf B Biointerfaces ; 185: 110591, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31704606

RESUMO

Aluminium doped phosphate based bioglasses have potential applications in the field of bone tissue engineering, because of their excellent bioactivity and biocompatibility along with high mechanical strength and controlled dissolution. In the present study, 8ZnO-22Na2O-(24-x)CaO-46P2O5-xAl2O3 (where x = 0, 2, 4, 6, 8 and 10 mol%) glass system was synthesized and investigated by means of XRD, FTIR, SEM and EDS before and after immersion in SBF for 3, 7, 14 and 21days, the physic-chemical properties of the samples, including density and microhardness, evaluation of pH and weight loss of glasses in physiological fluid and cell cultural studies like cell viability, cytocompatability and cell proliferation by seeding rMSCs cells on the glass samples in order to throw some light on their structural properties. The results showed that, the density and Vickers hardness found to be increased with the increase in content of alumina due to the slight increase in the number of octahedrally coordinated Al3+ ions and stronger ionic cross linkages due to insertion of Al3+ ions between phosphate networks. The initial rise in pH and controlled solubility in SBF strongly supports the apatite layer development. The growth of the rMSCs cells on all samples showing good cytocompatability and proliferation up to 6 mol% Al2O3 after that decreases slightly with an increase in alumina content due to network forming action of Al3+ ions in zinc phosphate based glasses. The results confirmed the suitability of these glasses for clinical trials towards bone repair and regeneration resorbable implants.


Assuntos
Óxido de Alumínio/química , Materiais Biocompatíveis/farmacologia , Osso e Ossos/citologia , Cerâmica/química , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Fosfatos/química , Compostos de Zinco/química , Animais , Materiais Biocompatíveis/química , Osso e Ossos/efeitos dos fármacos , Sobrevivência Celular , Células Cultivadas , Células-Tronco Mesenquimais/efeitos dos fármacos , Ratos , Engenharia Tecidual
20.
Anal Chim Acta ; 1096: 26-33, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31883588

RESUMO

Accurate and sensitive detection of dopamine (DA) is fundamental to monitor and diagnose certain neurological diseases. Herein, highly ordered mesoporous ZnFe2O4 (OM-ZnFe2O4) is prepared via a facile nanocasting method and shows the highly sensitive in the electrochemical detection of DA. The optimized OM-ZnFe2O4-40 shows the most excellent activity for DA oxidation in a wide linear range from 2 to 600 nM with a quick response time of 5 s, high sensitivity of 0.094 nA nM-1 and a lower detection limit of 0.4 nM (S/N = 3). The electrode modified with OM-ZnFe2O4 is further successfully used to monitor the increase of DA concentration induced by K+-stimulation of living PC12 cells in a neurological environment. This work offers a simple and powerful strategy for designing electrodes for detecting DA in biological systems.


Assuntos
Dopamina/análise , Técnicas Eletroquímicas/instrumentação , Compostos Férricos/química , Compostos de Zinco/química , Animais , Técnicas Eletroquímicas/métodos , Desenho de Equipamento , Limite de Detecção , Células PC12 , Porosidade , Ratos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA