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1.
Chemosphere ; 239: 124823, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726520

RESUMO

Several studies have demonstrated that gypsum (CaSO4·2H2O) and calcite (CaCO3) can be important hosts of arsenic in contaminated hydrogeological systems. However, the extent to which microbial reducing processes contribute to the dissolution and transformation of carbonate and sulfate minerals and, thereby, to arsenic mobilization is poorly understood. These processes are likely to have a strong impact on arsenic mobility in iron-poor environments and in reducing aquifers where iron oxyhydroxides become unstable. Anoxic batch bioassays with arsenate (As(V)) coprecipitated with calcite, gypsum, or ferrihydrite (Fe(OH)3) were conducted in the presence of sulfate or molybdate to examine the impact of bioprocesses (i.e. As(V), sulfate, and Fe(III)-reduction) on arsenic dissolution, speciation, and eventual remineralization. Microbial reduction of As(V)-bearing calcite caused an important dissolution of arsenite, As(III), which remained in solution up to the end of the experiment (30 days). The reduction of As(V) from gypsum-As(V) also led to the release of As(III), which was subsequently remineralized, possibly as arsenic sulfides. The presence of sulfate triggered arsenic dissolution in the bioassays with ferrihydrite-As(V). This study showed that although gypsum and calcite have a lower capacity to bind arsenic, compared to iron oxides, they can play a critical role in the biogeochemical cycle of arsenic in natural calcareous and gypsiferous systems depleted of iron since they can be a source of electron acceptors for reducing bioprocesses.


Assuntos
Arsênico/química , Bactérias/metabolismo , Carbonato de Cálcio/química , Sulfato de Cálcio/química , Compostos Férricos/química , Arseniatos/química , Arsenicais/química , Arsenitos/química , Carbonatos/química , Água Subterrânea/química , Ferro/química , Molibdênio/química , Oxirredução , Solubilidade , Sulfatos/química , Sulfetos/química
3.
Ecotoxicol Environ Saf ; 186: 109791, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31627094

RESUMO

Uptake, translocation and speciation of As in rice plants have been investigated through hydroponic cultivations under stress from different As species. After germination, rice seedlings were treated with arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid (MMA) or dimethylarsinic acid (DMA) at concentrations of 50, 100, 150, 200 and 250 µg/L for 24 days. Only inorganic As species were detected in the rice plants treated with As(III) or As(V), indicating that rice seedlings could not methylate inorganic As in hydroponic culture. As(V) in the rice roots was readily reduced to As(III) after uptake; thus, As(III) was the dominant species in the rice roots (>60%) and shoots (>80%) regardless of As(III) or As(V) treatment. The increased As(III) proportion in the nutrient solutions was due to the efflux of As(III) from the rice roots. MMA with relatively low stability in the blank nutrient solution was demethylated to As(III). Moreover, demethylation and methylation of MMA might occur simultaneously in rice plants. Specific proportions of MMA and AsB were observed in the rice roots treated with DMA, implying that MMA and AsB were the DMA metabolites in rice roots after detoxification.


Assuntos
Arsenicais/química , Arsenicais/farmacologia , Oryza/efeitos dos fármacos , Oryza/metabolismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo , Arsenicais/metabolismo , Transporte Biológico , Hidroponia , Metilação , Oxirredução , Raízes de Plantas/metabolismo , Plântula/metabolismo
4.
Molecules ; 24(18)2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31489942

RESUMO

Strong piezoresistivity of InAsP nanowires is rationalized with atomistic simulations coupled to Density Functional Theory. With a focal interest in the case of the As(75%)-P(25%) alloy, the role of crystal phases and phosphorus atoms in strain-driven carrier conductance is discussed with a direct comparison to nanowires of a single crystal phase and a binary (InAs) alloy. Our analysis of electronic structures presents solid evidences that the strong electron conductance and its sensitivity to external tensile stress are due to the phosphorous atoms in a Wurtzite phase, and the effect of a Zincblende phase is not remarkable. With several solid connections to recent experimental studies, this work can serve as a sound framework for understanding of the unique piezoresistive characteristics of InAsP nanowires.


Assuntos
Arsenicais/química , Índio/química , Nanofios/química , Fósforo/química , Teoria da Densidade Funcional , Condutividade Elétrica , Tamanho da Partícula , Propriedades de Superfície
5.
J Agric Food Chem ; 67(32): 9032-9038, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31334646

RESUMO

It is estimated that approximately 200 million people are exposed to arsenic levels above the World Health Organization provisional guideline value, and various agencies have indicated the need to reduce this exposure. In view of the difficulty of removing arsenic from water and food, one alternative is to reduce its bioavailability (the amount that reaches the systemic circulation after ingestion). In this study, dietary components [glutathione, tannic acid, and Fe(III)] were used to achieve this goal. As(III) or As(V) (1 mg/kg body weight) was administered daily to BALB/c mice, along with the dietary components, for 15 days. The results confirm the efficacy of Fe(III) and glutathione as reducers of arsenic bioavailability and tissue accumulation. Also, these treatments did not result in reductions of Ca, K, P, and Fe contents in the liver. These data suggest that use of these two compounds could be part of valid strategies for reducing inorganic arsenic exposure in chronically exposed populations.


Assuntos
Arsenicais/metabolismo , Compostos Férricos/química , Glutationa/química , Animais , Arsenicais/química , Disponibilidade Biológica , Exposição Dietética/análise , Exposição Dietética/prevenção & controle , Compostos Férricos/metabolismo , Contaminação de Alimentos/análise , Glutationa/metabolismo , Fígado/metabolismo , Pulmão/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Oryza/química , Oryza/metabolismo
6.
Sci Total Environ ; 684: 360-370, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31153082

RESUMO

Exposure to arsenic (As) through rice consumption potentially threatens millions of people worldwide. Understanding is still lacking the recycling impacts of rice residues on As phytoavailability in paddy soils and is of indisputable importance in providing a sustainable and effective measure to decrease As accumulation in rice grain. Herein, we examined the effects of rice husk biochar (RHB) and rice husk ash (RHA) on As grain speciation, and As dynamics in the soil porewater and solid-phase fractions. The results corroborated that both the RHB and RHA (0.64% w/w) treatments significantly (p < 0.05) decreased inorganic As accumulation in rice grain to 0.27-0.29 mg kg-1, which was below the maximum inorganic As level in husked rice (0.35 mg kg-1) established by the Codex. The residual phase (F6 = 90% of total soil As) as quantified by the sequential extraction was the dominant As pool; the fractions were subsequently transformed into several As pools associated with soluble and exchangeable (F1), organically bound (F2), Mn oxides (F3), poorly crystalline (F4) and crystalline (F5) Fe oxides during the rice growing periods. The Si-rich amendments enhanced the residual phase formation upon soil flooding, which decreased the As availability to rice plant. The inorganic grain-As concentrations were well explained by the soil-extractable As concentrations in the F2, F3, F5, and F6 fractions. The pore-water analysis indicated that Mn oxides were important sources and sinks for As released to the soil solution. Our findings shed light on the beneficial role of RHB and RHA in alleviating inorganic As uptake in paddy rice.


Assuntos
Arsenicais/análise , Carvão Vegetal/química , Cinza de Carvão/química , Oryza/efeitos dos fármacos , Silício/química , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Arsênico/análise , Arsênico/química , Arsenicais/química , Grão Comestível/química , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/metabolismo , Água Subterrânea/química , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Solo/química
7.
Iran J Immunol ; 16(2): 170-181, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31182691

RESUMO

BACKGROUND: Realgar, an arsenic tetrasulfide compound, is a highly recognized traditional Chinese medicinal prescription that has been widely used to treat various diseases such as inflammatory diseases. However, there are still some problems in the clinical treatment of Realgar, such as large oral dose and high potential toxicity. OBJECTIVE: To evaluate effects of Realgar nanoparticles on lupus nephritis (LN) in vivo in MRL/lpr mice. METHODS: Ten-week mice were orally administered every day for eight consecutive weeks except the mice of normal model groups. The serum levels of anti-ds-DNA antibody IgG, IgM, IFN-γ, Creatinine (Cr), and blood urea nitrogen (BUN) were determined, and 24-hour urine protein was also measured. Renal inflammatory pathology analysis was assessed by hematoxylin-eosin (H&E) staining. The expression of phosphorylated signal transducer and activator of transcription 1 (p-STAT 1) and Janus Kinase 1 (JAK 1) in kidney tissue was determined by direct reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). RESULTS: The mice treated with Realgar nanoparticle in the high dose-treated (Realgar HD, 0.03 g/kg/d) group exhibited significantly reduced serum levels of anti-dsDNA (p<0.01), IgG (p<0.01), IgM (p<0.01), BUN (p<0.01), Cr (p<0.01), and inflammatory cytokine IFN-γ (p<0.01) as well as proteinuria (p<0.01) compared to the untreated model MRL/lpr mice. Additionally, high doses of Realgar nanoparticles significantly suppressed the phosphorylations of STAT 1(p<0.01) and the renal pathological changes. CONCLUSIONS: The study indicates that Realgar nanoparticles may be a potential agent to treat LN, and the down-regulated p-STAT1 expression suggests that it may be one of the LN treatment targets for Realgar nanoparticles.


Assuntos
Arsenicais/uso terapêutico , Rim/patologia , Nefrite Lúpica/terapia , Nanopartículas/uso terapêutico , Fator de Transcrição STAT1/metabolismo , Sulfetos/uso terapêutico , Animais , Arsenicais/química , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Mediadores da Inflamação/metabolismo , Janus Quinase 1/metabolismo , Medicina Tradicional Chinesa , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos MRL lpr , Nanopartículas/química , Transdução de Sinais , Sulfetos/química
8.
Environ Sci Pollut Res Int ; 26(22): 22929-22944, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31177413

RESUMO

Arsenic exposure route for humans is through the drinking of contaminated water and intake of arsenic-contaminated foods, particularly in arsenic-exposed areas of Bengal delta. Transport of the arsenic-contaminated crops and vegetables grown using arsenic-contaminated groundwater and soil in arsenic-exposed areas to the uncontaminated sites and consequent dietary intakes leads to great threats for the population residing in non-endemic areas with respect to consumption of arsenic through drinking water. We have studied the food materials collected from 30 families and their dietary habits, apparently who consume arsenic-free drinking water as well as 9 well-known markets of Kolkata city. The total and inorganic arsenic intake has been estimated from the collected foodstuffs from the market basket survey (n = 93) and household survey (n = 139), respectively for human risk analysis. About 100% of the collected samples contained detectable amount of arsenic (range 24-324 µg/kg), since the origin of the food materials was somewhere from arsenic-endemic areas. The daily consumption of inorganic arsenic (iAs) from rice grain and vegetables for adult and children is 76 µg and 41.4 µg, respectively. Inorganic arsenic (mainly arsenite and arsenate) contributes approximately 88% of the total content of arsenic in vegetable. In most of the cases, insufficient nutrient intake by the studied population may lead to arsenic toxicity in the long run. An independent cancer risk assessment study on the same population indicates that the main risk of cancer might appear through the intake of arsenic-contaminated rice grain and cereals.


Assuntos
Arsênico/análise , Arsenicais/análise , Contaminação de Alimentos/análise , Poluentes do Solo/análise , Adulto , Agricultura , Arsênico/química , Arsenicais/química , Criança , Produtos Agrícolas , Água Potável/análise , Grão Comestível/química , Água Subterrânea , Humanos , Oryza , Solo , Verduras , Poluentes Químicos da Água/análise
9.
Nanomedicine (Lond) ; 14(9): 1173-1189, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31050596

RESUMO

Aim: Preparation of a herbometallic nano-drug, Rasa Manikya nanoparticle (RMNP) and investigation of its antimicrobial, and anticancer activity. Materials & methods: Physicochemical characterizations of RMNP were performed using different analytical methods. The antimicrobial and anticancer potential of RMNPs were assessed by an in vitro cellular assay. Bacterial cell wall lysis was observed by field emission scanning electron microscopy and mitochondrial metabolism alteration factor was measured via standard method. Results: Physicochemical analysis confirmed that RMNP was rich in mineral constituents. Synergistic effect of RMNPs enhanced lysis of bacterial peptidoglycan layers and impaired cellular redox balance, GSH/NADPH level followed by induction of cell apoptosis. Conclusion: The present study confirms that RMNP can be used as a dual therapeutic option for combating drug-resistant microbial strains and breast cancer.


Assuntos
Antibacterianos/química , Antineoplásicos/química , Arsenicais/química , Nanopartículas Metálicas/química , Estresse Oxidativo , Preparações de Plantas/química , Sulfetos/química , Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Arsenicais/farmacologia , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Enterobacter/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Humanos , Medicina Ayurvédica , Testes de Sensibilidade Microbiana , Oxirredução , Preparações de Plantas/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Sulfetos/farmacologia
10.
Methods Mol Biol ; 1967: 295-304, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31069779

RESUMO

Conjugates of 4-(N-(S-glutathionylacetyl)amino)phenylarsonous acid (GSAO) with optical or radionuclide probes are able to image cell death in vivo. GSAO conjugates are retained in the cytosol of dying and dead cells via the formation of covalent bonds between the As(III) ion and the thiol groups of proximal cysteine residues. Here we describe the method for preparing a NODAGA-GSAO conjugate and its radiolabeling with gallium-68 (68Ga-NODAGA-GSAO) for positron-emission tomography (PET) imaging of cell death.


Assuntos
Morte Celular/genética , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos/química , Tolueno/análogos & derivados , Acetatos/química , Acetatos/uso terapêutico , Animais , Arsenicais/química , Arsenicais/uso terapêutico , Radioisótopos de Gálio/química , Radioisótopos de Gálio/uso terapêutico , Glutationa/análogos & derivados , Glutationa/química , Glutationa/uso terapêutico , Compostos Heterocíclicos com 1 Anel/química , Compostos Heterocíclicos com 1 Anel/uso terapêutico , Humanos , Radioisótopos/administração & dosagem , Radioisótopos/química , Compostos Radiofarmacêuticos/uso terapêutico , Tolueno/química
11.
Environ Pollut ; 251: 651-658, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31108298

RESUMO

Dietary arsenic (As) intake from food is of great concern, and developing a reliable model capable of predicting As concentrations in plant edible parts is desirable. In this study, pot experiments were performed with 16 Chinese upland soils spiked with arsenate [As(V)] to develop a predictive model for As concentrations in pepper fruits (Capsicum annum L.). Our results showed that after three months' aging, concentrations of bioavailable As (extracted by 0.05 M NH4H2PO4) in various soils varied widely, depending on soil total As concentrations and soil properties such as soil pH and amorphous iron (Fe) contents. Furthermore, both the bioconcentration factor (BCF, denoted as the ratio of fruit As to soil As) and total As concentrations in pepper fruits were largely determined by concentrations of bioavailable As, which explained 27% and 69% variations in the BCF and fruit As concentrations, respectively. Apart from bioavailable As, soil pH and Fe contents were another two important factors influencing As accumulation in pepper fruits. Taking the three factors into account, concentrations of fruit As can be well predicted using a stepwise multiple linear regression (SMLR) analysis (R2 = 0.80, RMSE = 0.17). Arsenic species in soils and edible parts were also analyzed. Although As(V) predominated in soils (>96%), As in pepper fruits presented as As(V) (46%) and arsenite [As(III)] (39%) with small amount of methylated As (<15%). Aggregated boosted tree (ABT) analysis revealed that inorganic As concentrations in pepper fruits were determined by concentrations of bioavailable As, phosphorus (P) and Fe in soils. In contrast to inorganic As, methylated As concentrations were not correlated with those factors in soils. Taken together, this study established an empirical model for predicting As concentrations in pepper fruits. The predictive model can be used for establishing the As threshold in fruit vegetable farming soils.


Assuntos
Arsenicais/farmacocinética , Capsicum/metabolismo , Poluentes do Solo/farmacocinética , Arsenicais/análise , Arsenicais/química , Arsenicais/metabolismo , Disponibilidade Biológica , Contaminação de Alimentos/análise , Frutas/metabolismo , Concentração de Íons de Hidrogênio , Ferro/análise , Fósforo/análise , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/química , Poluentes do Solo/metabolismo
12.
Phytochemistry ; 164: 243-251, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31128818

RESUMO

Lipid-like compounds containing a dimethylarsinoyl group, i.e. Me2As(O)-, have been identified by liquid chromatography/inductively coupled plasma mass spectrometry (LC/ICP-MS) and non-aqueous reversed-phase high-performance liquid chromatography (positive and/or negative high-resolution tandem electrospray ionization mass spectrometry (NARP-HPLC/HR-ESI+(-)-MS/MS) from three strains of green algae of the genus Coccomyxa (Trebouxiophyceae, Chlorophyta). The algae were cultivated in a medium containing 10 g arsenic/L, i.e. 133.5 mmol/L of Na2HAsO4.7H2O. After extraction by methyl-tert-butyl ether (MTBE), total lipids were analyzed by ICP-MS or ESI-MS without any further separation or fractionation. A total of 39 molecular species of arsenic triacylglycerols (AsTAG), 15 arsenic phosphatidylcholines (AsPC), 8 arsenic phosphatidylethanolamines (AsPE), 6 arsenic phosphatidylinositols (AsPI), 2 arsenic phosphatidylglycerols (AsPG) and 5 unknown lipids (probably ceramides) were identified. The structures of all molecular species were confirmed by tandem MS. Dry matter of the individual strains contained different amounts of total arsenolipids, i.e. C. elongata CCALA 427 (0.32 mg/g), C. onubensis (1.48 mg/g), C. elongata S3 (2.13 mg/g). On the other hand, there were only slight differences between strains in the relative abundances of individual molecular species. Possible biosynthesis of long-chain lipids with the end group Me2As(O) has also been suggested.


Assuntos
Arsenicais/isolamento & purificação , Chlorella/química , Lipídeos/isolamento & purificação , Arsenicais/química , Arsenicais/metabolismo , Chlorella/metabolismo , Lipídeos/química , Estrutura Molecular
13.
J Agric Food Chem ; 67(17): 4987-4994, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30994339

RESUMO

Despite rice consumption, rice bran as a byproduct of rice milling contains higher arsenic (As). The present study evaluated the metabolic potency of in vitro cultured human colon microbiota toward As from five rice bran products with 0.471-1.491 mg of As/kg. Arsenic bioaccessibility ranged from 52.8 to 78.8% in the gastric phase, and a 1.2-fold increase (66.0-95.8%) was observed upon the small intestinal phase. Subsequently, a significant decline of As bioaccessibility (11.3-63.6%) and a high methylation percentage of 18.5-79.8% were found in the colon phase. The predominant As species in the solid phase was always As(V) (49.6-63.4%), and As-thiolate complexes increased by 10% at the end of colon incubation. Human gut microbiota could induce As bioaccessibility lowering and As transformation in rice bran, which illustrated the importance of food-bound As metabolism in the human body. This will result in a better understanding of health implications associated with As exposures.


Assuntos
Arsenicais/metabolismo , Bactérias/metabolismo , Colo/metabolismo , Intestino Delgado/metabolismo , Oryza/química , Arsenicais/química , Bactérias/classificação , Bactérias/isolamento & purificação , Biotransformação , Colo/química , Colo/microbiologia , Microbioma Gastrointestinal , Humanos , Intestino Delgado/química , Intestino Delgado/microbiologia , Metilação , Oryza/metabolismo , Medição de Risco
14.
Nano Lett ; 19(4): 2674-2681, 2019 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-30908918

RESUMO

We report on experimental determination of the strain and bandgap of InAsP in epitaxially grown InAsP-InP core-shell nanowires. The core-shell nanowires are grown via metal-organic vapor phase epitaxy. The as-grown nanowires are characterized by transmission electron microscopy, X-ray diffraction, micro-photoluminescence (µPL) spectroscopy, and micro-Raman (µ-Raman) spectroscopy measurements. We observe that the core-shell nanowires are of wurtzite (WZ) crystal phase and are coherently strained with the core and the shell having the same number of atomic planes in each nanowire. We determine the predominantly uniaxial strains formed in the core-shell nanowires along the nanowire growth axis and demonstrate that the strains can be described using an analytical expression. The bandgap energies in the strained WZ InAsP core materials are extracted from the µPL measurements of individual core-shell nanowires. The coherently strained core-shell nanowires demonstrated in this work offer the potentials for use in constructing novel optoelectronic devices and for development of piezoelectric photovoltaic devices.


Assuntos
Arsenicais/isolamento & purificação , Medições Luminescentes/métodos , Nanofios/química , Arsenicais/química , Estruturas Metalorgânicas/química , Tamanho da Partícula , Análise Espectral Raman , Difração de Raios X
15.
J Agric Food Chem ; 67(15): 4154-4159, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30896158

RESUMO

Arsenic, a naturally occurring metalloid found in certain foods, exists in various redox states and as inorganic and organic species, each with varying levels of toxicity. International regulatory bodies have imposed allowable maximums for total arsenic in wine ranging between 100 and 200 µg/L. Typical commercial wine levels are within these limits. However, a better understanding of viticultural and enological practices impacting total arsenic and arsenic species in grapes and wines is needed to ensure levels remain low. This perspective discusses current information on factors impacting the arsenic content of grapes and wines and the analytical approaches for monitoring inorganic and organic species.


Assuntos
Arsenicais/química , Vitis/química , Vinho/análise , Contaminação de Alimentos/análise , Tecnologia de Alimentos , Espectrometria de Massas
16.
Int J Biol Macromol ; 131: 971-979, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30926490

RESUMO

In this study, a MT(Al)/calcium alginate [MT(Al)@CA] microsphere structure was prepared using sodium alginate (SA) and MT(Al). In order to achieve [MT(Al)@CA] microspheres with a high stability and chemical resistance, glutaraldehyde was used as the crosslinking agent to graft the microspheres and ethylenediamine (ED) into a new type of ED-functionalized MT(Al)@CA microsphere structure similar to a core-shell-type structure [MT(Al)@CA-ED]. This core-shell/bead-like structure was characterized and analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The adsorption performance of the core-shell/bead-like structure for As(V) in solution was studied. The effects of the initial As(V) concentration, reaction time, pH, and different reaction temperatures on the reaction process were studied. The results indicate that at a pH of 4, the removal rate of As(V) by the core-shell/bead-like MT(Al)@CA-ED could reach 94.85% after 150 min. The adsorption process is highly consistent with the Langmuir isotherm model (R2 = 0.9983) and pseudo-second-order kinetic model (R2 = 0.9973). The maximum adsorption capacity could reach 61.94 mg/g. Regeneration experiments showed that the adsorption efficiency of As(V) after six cycles was >80%.


Assuntos
Alginatos/química , Arsenicais/química , Bentonita/química , Etilenodiaminas/química , Íons/química , Microesferas , Adsorção , Concentração de Íons de Hidrogênio , Análise Espectral , Temperatura Ambiente , Poluentes Químicos da Água/química
17.
Biochemistry ; 58(6): 799-808, 2019 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-30532959

RESUMO

Forster resonance energy transfer (FRET)-based biosensors have been recently applied to the study of biological pathways. In this study, a new biosensor was validated for the first time in live HEK293 and steroidogenic MLTC-1 cell lines for studying the effect of the PDE5 inhibitor on the hCG/LH-induced steroidogenic pathway. The sensor improves FRET between a donor (D), the fluorescein-like diarsenical probe that can covalently bind a tetracysteine motif fused to the PDE5 catalytic domain, and an acceptor (A), the rhodamine probe conjugated to the pseudosubstrate cGMPS. Affinity constant ( Kd) values of 5.6 ± 3.2 and 13.7 ± 0.8 µM were obtained with HEK293 and MLTC-1 cells, respectively. The detection was based on the competitive displacement of the cGMPS-rhodamine conjugate by sildenafil; the Ki values were 3.6 ± 0.3 nM (IC50 = 2.3 nM) in HEK293 cells and 10 ± 1.0 nM (IC50 = 3.9 nM) in MLTC-1 cells. The monitoring of both cAMP and cGMP by bioluminescence resonance energy transfer allowed the exploitation of the effects of PDE5i on steroidogenesis, indicating that sildenafil enhanced the gonadotropin-induced progesterone-to-testosterone conversion in a cAMP-independent manner.


Assuntos
Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/metabolismo , Inibidores da Fosfodiesterase 5/metabolismo , Progesterona/biossíntese , Citrato de Sildenafila/metabolismo , Testosterona/biossíntese , Animais , Arsenicais/química , Técnicas Biossensoriais/métodos , Domínio Catalítico , Linhagem Celular Tumoral , Gonadotropina Coriônica/farmacologia , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/química , Cisteína/química , Transferência Ressonante de Energia de Fluorescência/métodos , Corantes Fluorescentes/química , Células HEK293 , Humanos , Hormônio Luteinizante/farmacologia , Camundongos , Inibidores da Fosfodiesterase 5/farmacologia , Progesterona/metabolismo , Ligação Proteica , Rodaminas/química , Citrato de Sildenafila/farmacologia , Testosterona/metabolismo
18.
Chemosphere ; 218: 670-679, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30504042

RESUMO

The potential hazards of Fe(III)-As(V) co-precipitate under reducing conditions are incompletely known. This work investigated the effect of Fe(III) reduction by ascorbic acid (AH2) on the stability of Fe(III)-As(V) co-precipitate at different pHs and Fe/As molar ratios. The results showed that As (14-98.9%) and Fe (27.9-99.3%) were significantly released into solution by 79.9-97.5% Fe(III) reduction of the co-precipitate (Fe/As molar ratios of 3 and 5) at pH 5-9. More As release was observed with the increase of pH (6-9) or decrease in Fe/As molar ratio (from 5 to 3). This could be attributed by oxalate, the final product of AH2 decomposition, which strongly competed with As(V) for Fe(II) at higher pH or lower Fe/As molar ratio, inhibiting parasymplesite accumulation and then causing more As mobilization. The stability of Fe(III)-As(V) co-precipitate with AH2 upon Fe(III) reduction was lower than that in oxic environment. Compared with produced Fe(II,III) (hydr)oxides in the presence of hydroquinone (QH2), humboldtine was formed during the long-term reactions of Fe(III)-As(V) co-precipitate with AH2. The findings of this study implied that parasymplesite and humboldtine as secondary solid products were environmental relevant and mainly responsible for As(V) and Fe(II) immobilization.


Assuntos
Arsenicais/química , Ácido Ascórbico/química , Compostos Férricos/química , Arsenicais/metabolismo , Precipitação Química , Concentração de Íons de Hidrogênio , Ferro/química , Oxirredução , Óxidos/química
19.
Talanta ; 192: 270-277, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30348389

RESUMO

Antibiotic resistant bacteria have become a threat to world health. An advanced method of detection, based on matrix assisted laser desorption ionization time-of-flight mass spectroscopy can identify bacteria relatively rapidly, but it is not suitable to measure bacterial antibiotic resistance. Biosensors may be able to detect resistance by monitoring growth after capture on sensor surfaces but this option has not been addressed adequately. We have evaluated the growth of Escherichia coli after capture in 96 well microplates and observed that growth/capture efficiency was relatively similar for antibody-based techniques, but non-specific capture varied considerably. We confirm that neutravidin binds E. coli non-specifically, which limited its use with biotinylated antibodies or aptamers. Centrifugation enhanced bacterial growth/capture considerably, indicating that procedures enhancing the interaction between bacteria and surface-bound antibody have the potential to improve growth efficiency. Capture and growth required larger numbers of bacteria than capture and detection on biosensor surfaces. Previously, we reported that the minimum concentration of live E. coli required for initiating growth on a GaAs/AlGaAs biosensor was ~ 105 CFU/mL (Nazemi et al., 2018), and we speculated that this could be related to the poisonous effect of Ga- and As-ions released during dark corrosion of the biosensor, however in the present report we observed that the same minimum concentration of E. coli was required for growth in an ELISA plate. Thus, we argue that this limitation was related rather to bacterial inhibition by the capture antibodies. Indeed, antibodies at titres designed to capture bacteria inhibited bacterial growth when the bacteria were added to growth medium at titres less than 105 CFU/mL, indicating that antibodies may be responsible for the higher limits of sensitivity due to their potential to restrict bacterial growth. However, we did not observe E. coli release after 6 h following the capture indicating that these bacteria did not degrade antibodies.


Assuntos
Anticorpos/imunologia , Técnicas Biossensoriais/métodos , Escherichia coli K12/crescimento & desenvolvimento , Escherichia coli K12/imunologia , Animais , Anticorpos/metabolismo , Arsenicais/química , Avidina/química , Galinhas/imunologia , Escherichia coli K12/química , Escherichia coli K12/metabolismo , Fluorescência , Gálio/química , Cabras/imunologia , Proteínas de Fluorescência Verde/química , Ligantes
20.
Analyst ; 144(2): 536-542, 2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30406221

RESUMO

Fluorescent probes are powerful tools for investigating reactive oxygen species (ROS) in living organisms. The overproduced "primary" ROS of superoxide anions (O2˙-) cause a chain of oxidative damage. In order to monitor O2˙- level fluctuations in living cells, we synthesized two reaction-type probes of TPA-DHP-1,2,3 and TPA-PPA-1,2,3, which were composed of an electron-rich triphenylamine (TPA) and the very active functional groups of dihydropyridine (DHP) and pyridinium (PPA). Intriguingly, DHP and PPA were able to carry out easy proton abstractions and nucleophilic reactions in the presence of O2˙-, resulting in the corresponding products with sharp wavelength shifts, and elevated fluorescence intensities. Therefore, undesirable background fluorescence interference can be reduced during the monitoring and imaging process. Meanwhile, the developed dual-channel monitoring strategy not only provides observations of the O2˙- level fluctuations, but could also be employed to image the dynamic accumulation process of probes in the different cell organelles. Therefore, the design could provide a simple, accurate and universal platform for biological applications in future research work.


Assuntos
Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Imagem Óptica/métodos , Superóxidos/metabolismo , Arsenicais/química , Células HeLa , Humanos , Modelos Moleculares , Conformação Molecular , Fenômenos Ópticos , Fatores de Tempo
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