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1.
J Environ Sci (China) ; 85: 147-155, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471021

RESUMO

Polymer hydrogel-based materials have been shown to act as novel Fenton catalysts for water treatment, but the rational design of hydrogel-based catalysts with good stability has been a great challenge. To increase the stability and activity of polymer-based Fenton catalysts, uniform urchin-like α-Fe2O3 was grown in situ in a PVA carrier matrix here. PVA molecules promoted the growth of urchin-like α-Fe2O3, and then the PVA hydrogel acted as a barrier and carrier to reduce agglomeration. Through coordination by hydroxyl groups, PVA had good combination with Fe ions and α-Fe2O3. The formation of Fe-O-C bonds between iron oxides and polymers was reported for the first time, enhancing the material stability during catalysis. Under higher PVA concentrations, the resulting composite hydrogel could generate more ˙OH due to the increase in the number of active sites because of the hairy urchin-like structure. In tetracycline degradation through a heterogeneous Fenton reaction, the resulting material had good catalytic activity from pH 2 to pH 10 with low iron leaching, good reusability and remained at a level of nearly 90% after five consecutive cycles. Density functional theory calculations were used to further prove the mechanism of structural change of the iron oxides. The HOMO and LUMO energies of the iron oxides changed from 5.428 and 4.899 eV to 5.926 and 5.310 eV, indicating that the presence of PVA could influence the charge of the iron atom. The results provide new insights into the preparation of polymer hydrogel-based heterogeneous Fenton catalysts with enhanced stability for water treatment.


Assuntos
Hidrogéis/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Compostos Férricos , Peróxido de Hidrogênio/química , Polímeros
2.
J Appl Oral Sci ; 27: e20180453, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411261

RESUMO

OBJECTIVE: This study was designed for the chemical activation of a 35% hydrogen peroxide (H2O2) bleaching gel to increase its whitening effectiveness and reduce its toxicity. METHODOLOGY: First, the bleaching gel - associated or not with ferrous sulfate (FS), manganese chloride (MC), peroxidase (PR), or catalase (CT) - was applied (3x 15 min) to enamel/dentin discs adapted to artificial pulp chambers. Then, odontoblast-like MDPC-23 cells were exposed for 1 h to the extracts (culture medium + components released from the product), for the assessment of viability (MTT assay) and oxidative stress (H2DCFDA). Residual H2O2 and bleaching effectiveness (DE) were also evaluated. Data were analyzed with one-way ANOVA complemented with Tukey's test (n=8. p<0.05). RESULTS: All chemically activated groups minimized MDPC-23 oxidative stress generation; however, significantly higher cell viability was detected for MC, PR, and CT than for plain 35% H2O2 gel. Nevertheless, FS, MC, PR, and CT reduced the amount of residual H2O2 and increased bleaching effectiveness. CONCLUSION: Chemical activation of 35% H2O2 gel with MC, PR, and CT minimized residual H2O2 and pulp cell toxicity; but PR duplicated the whitening potential of the bleaching gel after a single 45-minute session.


Assuntos
Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/toxicidade , Clareadores Dentários/química , Clareadores Dentários/toxicidade , Clareamento Dental/métodos , Análise de Variância , Catalase/química , Sobrevivência Celular , Células Cultivadas , Cloretos/química , Cor , Polpa Dentária/química , Polpa Dentária/diagnóstico por imagem , Dentina/química , Dentina/efeitos dos fármacos , Compostos Ferrosos/química , Compostos de Manganês/química , Odontoblastos/efeitos dos fármacos , Peroxidase/química , Valores de Referência , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Fatores de Tempo
3.
Water Sci Technol ; 80(1): 126-133, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31461429

RESUMO

This work is dedicated to the removal of free cyanide from aqueous solution through oxidation with hydrogen peroxide H2O2 catalyzed by copper oxide nanoparticles. Effects of initial molar ratio [H2O2]0/[CN-]0, catalyst dose, temperature, pH and the catalyst stability on cyanide removal have been investigated. The use of copper oxide has improved the reaction rate showing catalytic activity. The cyanide removal efficiency was increased from 60% to 94% by increasing in the dose of catalyst from 0.5 g/L to 5.0 g/L. Increasing the temperature from 20 °C to 35 °C promotes cyanide removal and the four successive times re-use of catalyst shows good stability. Kinetics of cyanide removal was found to be of pseudo-first-order with respect to cyanide. The rate constants have been determined.


Assuntos
Cobre/química , Cianetos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Catálise , Peróxido de Hidrogênio/química , Oxirredução
4.
Analyst ; 144(17): 5284-5291, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31372627

RESUMO

5,10,15,20-Tetrakis(4-carboxyl phenyl)porphyrin (Por) modified Co(OH)2 deposited on the surface of GO nanocomposites (Por/Co(OH)2/GO) were prepared and characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and XRD. For the first time, H2TCPP/Co(OH)2/GO is found to have enhanced peroxidase-like activity and catalyze the oxidation of the substrate 3,3,5,5-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2). Notably, the colorless TMB rapidly transformed into blue oxTMB in just 60 s, which was easily observed visually. The catalytic kinetics of H2TCPP/Co(OH)2/GO is in accord with the Michaelis-Menten equation. The catalytic mechanism of H2TCPP/Co(OH)2/GO nanocomposites is attributed to hydroxyl radicals (˙OH), due to decomposition of H2O2, which is verified by using terephthalic acid as a fluorescent probe. What's more, H2O2 can be detected in a wide linear detection range from 5 to 35 mM with a detection limit of 0.385 mM. Furthermore, based on the excellent peroxidase-like activity of H2TCPP/Co(OH)2/GO, a colorimetric sensor is established to sensitively detect glutathione (GSH) in a linear range from 10 to 300 µM with a low detection limit of 9.5 µM.


Assuntos
Cobalto/química , Grafite/química , Hidróxidos/química , Nanocompostos/química , Peroxidases/química , Porfirinas/química , Benzidinas/química , Materiais Biomiméticos , Técnicas Biossensoriais/métodos , Catálise , Glutationa/análise , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Cinética , Limite de Detecção , Oxirredução , Sensibilidade e Especificidade , Propriedades de Superfície
5.
Bioresour Technol ; 291: 121840, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31349174

RESUMO

Three types of raw biochar (i.e. CBC, OBC, PBC produced from cornstalk, orange peel and peanut hull, respectively) and the modified ones (i.e., KMnO4-, KOH- and H3PO4-treatment) were employed to activate H2O2 for the removal of tetracycline (TC). The effects of pyrolysis temperatures, H2O2 concentration and initial pH were examined. TC removal by raw biochars w/o H2O2 was dependent on the feedstock and pyrolysis temperature of biochar, but the removal efficiency was still quite low under optimum conditions. The KMnO4-treatment significantly enhanced the adsorption of TC on all three biochars, but only enhanced the TC removal by CBC + H2O2. The KOH-treatment had insignificant effect on the adsorption of TC on biochar, but improved the performance of CBC/PBC + H2O2. The H3PO4-treatment had a negative impact on TC removal by biochar w/o H2O2. Overall, H2O2 could either enhance or decrease the TC removal by biochar, depending on biochar type, H2O2 concentration and solution pH.


Assuntos
Antibacterianos/química , Carvão Vegetal/química , Peróxido de Hidrogênio/química , Tetraciclina/química , Adsorção , Concentração de Íons de Hidrogênio
6.
Gene ; 712: 143945, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31279712

RESUMO

Reactive oxygen species, generated in all the aerobic organisms, can cause oxidative stress. Excessive ROS may become a source of carcinogen due to DNA damage, lipid peroxidation, cell injury, and cell death. In order to prevent these adverse effects of ROS, antioxidant enzymes have evolved in aerobic organisms. Catalase is a major antioxidant enzyme that breaks down excessive H2O2 and inhibits apoptotic cell death. Here we molecularly characterized catalase from red-lip mullet. The cDNA sequence of LhCAT consists of an ORF of 1545 bp, which encodes a 527 amino acid peptide (~60 kDa). Based on bioinformatics analysis, LhCAT possesses a domain architecture characteristic of catalases, including a catalase proximal active site signature and a catalase proximal heme-ligand signature. It also has heme and NADPH binding sites homologous to previously described catalases. Pairwise alignment with its homologs revealed that LhCAT shares 95.1% identity with Oplegnathus fasciatus catalase and 97.4% similarity with Sparus aurata catalase. An uprooted phylogenetic tree demonstrated that LhCAT resides in a clade with catalases from other teleosts and exhibits a close relationship with Oplegnathus fasciatus catalase. Among twelve tissue types, we observed the highest LhCAT mRNA expression in the liver, followed by blood. Immune challenge by Lactococcus garvieae, or Poly I:C in the blood or spleen resulted in up-regulation at 24 h post injection. We also tested the antioxidant activity of recombinant LhCAT against hydrogen peroxide and found its optimal concentration to be 12.5 µg/mL. Collectively, these data suggested that LhCAT play an important role in antioxidant defense and immune response of red-lip mullet.


Assuntos
Catalase/metabolismo , Proteínas de Peixes/metabolismo , Smegmamorpha , Adjuvantes Imunológicos , Animais , Antioxidantes/metabolismo , Catalase/genética , DNA Complementar/genética , Proteínas de Peixes/genética , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Heme/química , Peróxido de Hidrogênio/química , Sistema Imunitário , Ligantes , Fígado/enzimologia , Estresse Oxidativo , Filogenia , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Regulação para Cima
7.
Food Chem ; 298: 125093, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260960

RESUMO

The purpose of this study was to investigate the impact of ozonation process on the level of oxidative stress markers in raspberries stored at room temperature. Raspberry fruit was ozonated with an ozone concentration of 8-10 ppm for 30 min, every 12 h, for 72 h of storage at room temperature. Research showed that ozonated raspberries were characterized by higher activity of superoxide dismutase, ascorbate peroxidase and phenylalanine ammonia-lyase. In turn, the ability to generate superoxide anion radical and hydrogen peroxide by ozone-treated fruit was significantly lower than in the control sample due to higher activities of ROS detoxification systems.


Assuntos
Armazenamento de Alimentos/métodos , Frutas/metabolismo , Estresse Oxidativo , Ozônio/química , Rubus/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Ascorbato Peroxidases/metabolismo , Biomarcadores/química , Biomarcadores/metabolismo , Frutas/química , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Fenilalanina Amônia-Liase/metabolismo , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Rubus/química , Superóxido Dismutase/metabolismo , Superóxidos/química , Superóxidos/metabolismo , Temperatura Ambiente
8.
Anal Chim Acta ; 1078: 119-124, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358209

RESUMO

In this work, CaF2 nanoparticles were successfully synthesized by a simple direct precipitation method and firstly used as a peroxidase mimics for rapid and high sensitive colorimetric detection of aldosterone. The CaF2 nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The CaF2 nanoparticles can oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue product oxidized TMB (oxTMB) in the presence of H2O2 and this peroxidase-like activity of CaF2 is found out to follow Michaelis-Menten kinetics. Experiments showed that the catalytic mechanism of CaF2 nanoparticles was attributed to that it could result in the decomposition of H2O2 to produce hydroxyl radicals (•OH). The absorbance change value of the reaction system was linear with the aldosterone concentration in the range of 2.0-40.0 nM, and the detection limit was 0.6 nM. Moreover, the developed method was applied to detect aldosterone in human serum samples. It provides a new platform for enzyme functional simulation and analytical sensing research.


Assuntos
Aldosterona/sangue , Materiais Biomiméticos/química , Fluoreto de Cálcio/química , Nanopartículas Metálicas/química , Benzidinas/química , Materiais Biomiméticos/síntese química , Fluoreto de Cálcio/síntese química , Catálise , Colorimetria/métodos , Humanos , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Cinética , Limite de Detecção , Modelos Químicos , Oxirredução , Peroxidase/química , Temperatura Ambiente
9.
Food Chem ; 298: 125034, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31261013

RESUMO

A wash-free and label-free colorimetric biosensor for the amplified detection of aflatoxin B1 (AFB1) has been constructed by the integration of an ingenious hairpin DNA probe with exonuclease III (Exo III)-assisted signal amplification. The presence of the AFB1 activates the continuous cleavage reactions by Exo III toward a hairpin probe, resulting in the autonomous accumulation of numerous free G-quadruplex sequences, which can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a colorimetric response. The naked-eye biosensor is ultrasensitive, enabling the visual detection of trace amounts of AFB1 as low as 1 pM without instrumentation. The sensor is robust and can work even when challenged with complex sample matrices such as peanut samples. With the advantages of simple operation, wash-free and label-free format, visible and intuitive output, and low cost, the naked-eye based colorimetric biosensor is expected to have potential applications for in-field detection of AFB1.


Assuntos
Aflatoxina B1/análise , Técnicas Biossensoriais/métodos , Colorimetria/métodos , Contaminação de Alimentos/análise , Benzidinas/química , Sondas de DNA/química , Exodesoxirribonucleases/química , Análise de Alimentos/métodos , Quadruplex G , Peróxido de Hidrogênio/química , Limite de Detecção
10.
Anal Chim Acta ; 1075: 144-151, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31196420

RESUMO

Salmonella is a widely distributed, extremely harmful bacteria, the presence of which requires confirmation via an on-site visual biosensor. In this study, we constructed a label-free, cascade amplification visualization biosensor for the sensitive and rapid detection of Salmonella enterica subsp. enterica serovar typhimurium based on the RDTG principle (recombinase polymerase amplification (RPA), duplex-specific enzyme (DSN) cleavage, terminal deoxynucleotidyl transferase (TdT) extension and G-quadruplexes output). Following DNA extraction of Salmonella spp., the first step in the construction involved the recognition and amplification of nucleic acids, carried out by RPA, to achieve the first signal amplification within 10 min. This RPA product was then specifically cleaved by DSN to produce a large number of small double-stranded DNA (dsDNA) products with 3'-OH within 15 min to achieve the second signal amplification. Thereafter, TdT was employed to empower these small 3'-OH dsDNA products to extend and produce a large number of long G-rich single-stranded DNAs (ssDNAs) within 20 min, thus realizing the third signal increase. These long G-rich ssDNA products displayed a color change that could be directly observed through the naked eye by adding H2O2/3,3',5,5'-tetramethylbenzidine (TMB). The RDTG biosensor for the detection of Salmonella spp. has several advantages, including a low limit of 6 cfu/mL. It is an isothermal-free instrument, simple to operate, with a rapid detection time of less than 1.5 h. Furthermore, it can be visually characterized and quantified by a microplate reader to detect Salmonella spp., in food and environmental samples, and it has broad application prospects.


Assuntos
Técnicas Biossensoriais/métodos , DNA Bacteriano/análise , Salmonella/isolamento & purificação , Técnicas de Tipagem Bacteriana/métodos , Benzidinas/química , DNA Nucleotidilexotransferase/química , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , DNA de Cadeia Simples/análise , DNA de Cadeia Simples/química , DNA de Cadeia Simples/genética , Contaminação de Alimentos/análise , Microbiologia de Alimentos , Quadruplex G , Peróxido de Hidrogênio/química , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico/métodos , Recombinases/química , Salmonella/genética , Sensibilidade e Especificidade , Iogurte/microbiologia
11.
Environ Pollut ; 251: 921-929, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31234258

RESUMO

The fast-growing production and application of carbon nanotube (CNT) materials in a variety of industrial products inevitably lead to their release to wastewater and surface water. CNT would experience oxidization in wastewater treatment plant due to the presence of large amount of disinfectants, such as H2O2 and O3, which in turn affects the environmental fates and risks of CNT. In this study, oxidized CNT materials (O-CNTs) were prepared by treating CNT with H2O2/UV and O3 (denoting as H2O2-CNT and O3-CNT, respectively). A variety of characterizations indicated that oxygen containing groups were generated on CNT surface upon the oxidation, and the O/C ratio increased in the order of pristine CNT < H2O2-CNT < O3-CNT. In the presence of Na+, K+ and Mg2+, the O-CNTs displayed better colloidal stability than the pristine CNT, and the stability increased with the oxidation degree (indicated by O/C ratio). This could be explained by the more negative surface charge and stronger hydrophilicity of the O-CNTs. Unexpectedly, in the presence of Ca2+, the most oxidized O3-CNT exhibited the poorest colloidal stability. The abundant carboxyl groups in O3-CNT provided effective binding sites for cation bridging effect through Ca2+ and led to stronger aggregation. Increasing pH was more favorable to disperse CNTs (both O-CNT and pristine CNT) in the presence of Na+, but much less effective in inhibiting the aggregation of O3-CNT in presence of Ca2+. This could be explained by the stronger cation bridging effect due to enhanced deprotonation the -COOH groups at higher pH conditions. The calculated Hamaker constants of the CNTs decreased with the oxidation degree, implying that there was lower van der Waals force between the O-CNTs. The Derjaguin-Landau-Verwey-Overbeek (DLVO) calculation confirmed that O-CNTs had to overcome higher energy barrier and thus showed better colloidal stability than the pristine CNT in the presence of Na+.


Assuntos
Coloides/química , Peróxido de Hidrogênio/química , Nanotubos de Carbono/química , Ozônio/química , Interações Hidrofóbicas e Hidrofílicas , Magnésio/química , Oxirredução , Potássio/química , Sódio/química , Águas Residuárias/química , Água/química
12.
Ultrason Sonochem ; 57: 22-28, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31208615

RESUMO

Bisphenol A (BPA) is an important emerging contaminant with endocrine-disrupting potential that has frequently been detected in aquatic environments. In this study, two types of hierarchically structured manganese dioxide/biochar nanocomposites (MnO2/BCs) were prepared for the first time via facile hydrothermal synthesis. The hydrothermal reaction was maintained at 100 °C for 6 h or 12 h, after which an ultrasound-assisted heterogeneous Fenton-like process was used to catalyze the removal of BPA under neutral pH condition. The characterization results indicated that MnO2 nanoparticles were successfully formed on the nanocomposite surfaces and had flower-like (δ-MnO2, 6 h) and urchin-like (α-MnO2, 12 h) morphology. This enabled a significant improvement in the catalytic activity of BPA removal by the reversible redox reaction. A series of experiments confirmed that the crystalline properties of the nanocomposites affected their catalytic activity. In particular, the α-MnO2/BCs exhibited catalytic activity in the ultrasound-assisted heterogeneous Fenton-like process and completely removed BPA within 20 min under the following conditions: [BPA]0 = 100 µM; [H2O2]0 = 10 mM; [catalyst]0 = 0.5 g/L; ultrasound = 20 kHz (130 W) at 40% amplitude; pH = 7.0 ±â€¯0.1; and temperature = 25 ±â€¯1 °C. This efficiency may have been due to the synergistic effect of ultrasound and α-MnO2/BCs, which simultaneously induce the effective generation of reactive free radicals and increase the mass transfer rate at the solid-liquid interface. Overall, these results demonstrated that hierarchical urchin-like α-MnO2/BCs have significant potential as an efficient and low-cost catalyst in ultrasound-assisted heterogeneous Fenton-like systems.


Assuntos
Compostos Benzidrílicos/isolamento & purificação , Carvão Vegetal/química , Compostos de Manganês/química , Nanocompostos/química , Óxidos/química , Fenóis/isolamento & purificação , Ondas Ultrassônicas , Catálise , Peróxido de Hidrogênio/química , Cinética , Oxirredução
13.
Environ Pollut ; 249: 1002-1010, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31146306

RESUMO

One attraction of using hydrochar (HC) and biochar (BC) in soil is their intrinsic affinity for organic contaminants. Oxidative ageing is likely to induce changes in physicochemical properties and functionality. To explore the long-term potential trajectories for corn stalk HC and BC to adsorb organic pollutants, we employed HC and BC exposure in 5% H2O2 to simulate oxidative ageing and get insights into mechanisms of atrazine adsorption on fresh and artificially aged materials. The physicochemical properties of fresh and aged materials were systematically compared using elemental analysis, SSA, FTIR, XPS and SEM-EDS, alongside K2Cr2O7/H2SO4 treatment to assess chemical oxidation stability. Atrazine is a typical herbicide chemical and hydrophobic organic pollutant. Adsorption isotherms of atrazine were used to reveal differences in mechanisms of sorption to BC and HC, by assessment before and ageing. BC freshly produced at 650 °C displayed higher capacity for atrazine sorption than BC produced at 500 °C, with a dominant role for π-π EDA interactions. The sorption capacity of HC freshly produced at 250 °C was higher than for HC produced at 200 °C HC, owing to higher C content and atrazine partitioning into the organic phase. Ageing increased the surface abundance of oxygenated functional groups for BC and HC and diminished bulk aromaticity. After ageing, atrazine sorption by high temperature BC was lower, but for HC it was increased. Such divergent effects must be considered when developing strategies to co-manage contaminants and carbon through the addition of carbonized materials to land.


Assuntos
Atrazina/análise , Carvão Vegetal/química , Herbicidas/análise , Poluentes do Solo/análise , Solo/química , Adsorção , China , Temperatura Alta , Peróxido de Hidrogênio/química , Oxirredução , Caules de Planta/química , Propriedades de Superfície , Zea mays/química
14.
Chemosphere ; 232: 377-386, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158632

RESUMO

Experimental tests were carried out in solid phase reactors on a microcosm scale, to removal old petroleum pollution by Fenton like oxidation process. In order to optimize the process, parametric study and statistically designed experiment have been undertaken by considering the amount influence of hydrogen peroxide (H2O2), endogenous and zero-valent iron (Fe) and ethylene diamine tetraacetic acid (EDTA) as chelating agent. The measurement of residual total petroleum hydrocarbons for different H2O2/Fe molar ratios and pH in the vicinity of neutrality highlighted oxidation rates ranging between 29.0 and 39.3%. The Fenton like (FL) oxidation was optimal for H2O2/Fe molar ratio of 15/4. The use EDTA led to result up 72.2% for H2O2/total Fe/EDTA molar ratio of 15/4/4 after 48 h of treatment. The statistical analysis of data by factorial design, has allowed the modeling of Fenton like process performances in the operating domain. It showed that hydrogen peroxide amount, interaction effects of oxidant-catalyst, catalyst-chelating agent, and oxidant-catalyst-chelating agent, were the influential parameters. Moreover, these results suggest that endogenous iron could be used as a source of iron in the presence of the chelating agent to activate FL oxidation. A better accuracy (80.0%) was obtained by statistical analysis for H2O2/endogenous Fe/EDTA molar ratio of 20/1/1.


Assuntos
Recuperação e Remediação Ambiental/métodos , Peróxido de Hidrogênio/química , Ferro/química , Petróleo/análise , Poluentes do Solo/análise , Solo/química , Catálise , Quelantes/química , Ácido Edético/química , Oxirredução
15.
Bioelectrochemistry ; 129: 124-134, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158797

RESUMO

The antioxidant properties of different plant extracts are usually claimed and used by food, medicine and cosmetic industry due to their health promoting capacities. In this study the presence of antioxidant compounds and the total antioxidant capacity of water-soluble extracts, prepared using two extraction methods and a variety of solvents, have been determined and a rapid screening method has been developed. Plant extracts characterisation, composition and antioxidant properties were confirmed by FTIR and Raman spectroscopies. Voltammetry, amperometry and electrochemical impedance were used to highlight the total antioxidant capacity of each extract using an electrochemical gold nanozyme-sensor based on the enzyme-like catalytic activity of gold nanoparticles. Both anodic area of cyclic voltammograms (10.31 µA V) and electrochemical index (153) calculated using differential potential voltammetry show the total content of antioxidant compounds, allowing to discriminate between different extracts. Amperometric total antioxidant capacity measurements were associated with those from classical chemiluminescence and good correlation has been found (Pearson's correlation coefficient of 0.958).


Assuntos
Antioxidantes/química , Técnicas Eletroquímicas/métodos , Ouro/química , Hippophae/química , Lavandula/química , Nanopartículas Metálicas/química , Extratos Vegetais/química , Antioxidantes/farmacologia , Técnicas Biossensoriais/métodos , Espectroscopia Dielétrica , Peróxido de Hidrogênio/química , Extratos Vegetais/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier
16.
J Environ Sci (China) ; 83: 1-7, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31221373

RESUMO

Due to the severe restrictions imposed by legislative frameworks, the removal of polyacrylamide (PAM) rapidly and effectively from produced wastewater in offshore oilfields before discharge is becoming an urgent challenge. In this study, a novel advanced oxidation process based on plasma operated in the gas-liquid interface was used to rapidly decompose PAM, and multiple methods including viscometry, flow field-flow fractionation multi-angle light scattering, UV-visible spectroscopy, and attenuated total reflectance-Fourier transform infrared spectroscopy were used to characterize the changes of PAM. Under a discharge voltage of 25 kV and pH 7.0, the PAM concentration decreased from 100 to 0 mg/L within 20 min and the total organic carbon (TOC) decreased from 49.57 to 1.23 mg/L within 240 min, following zero-order reaction kinetics. Even in the presence of background TOC as high as 152.2 mg/L, complete removal of PAM (100 mg/L) was also achieved within 30 min. The biodegradability of PAM improved following plasma treatment for 120 min. Active species (such as O3 and H2O2) were produced in the plasma. Hydroxyl radical was demonstrated to play an important role in the degradation of PAM due to the inhibitory effect observed after the addition of an ·OH scavenger, Na2CO3. Meanwhile, the release of ammonia and nitrate nitrogen confirmed the cleavage of the acylamino group. The results of this study demonstrated that plasma, with its high efficiency and chemical-free features, is a promising technology for the rapid removal of PAM.


Assuntos
Resinas Acrílicas/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Resinas Acrílicas/análise , Biodegradação Ambiental , Peróxido de Hidrogênio/química , Radical Hidroxila , Cinética , Campos de Petróleo e Gás , Oxirredução , Poluentes Químicos da Água/análise
17.
Food Chem ; 297: 124930, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253279

RESUMO

A new microfluidic chemiluminescence (MF-CL) method for rapidly assaying the total antioxidant capacity (TAC) of apple and pomegranate juices and honey samples was developed. The method exploited the NaHCO3-H2O2-Co2+ CL reaction. It was found that gallic acid (GA), catechin, caffeic acid, ferulic acid and rutin, as selected phenolic antioxidants, could suppress the CL reaction. The linear range and limit of detection of the method for the antioxidants were as follows: 0.5-3 mg L-1 and 0.27 mg L-1 for GA, 0.2-5.0 mg L-1 and 0.17 mg L-1 for catechin, 0.03-2.0 mg L-1 and 0.03 mg L-1 for caffeic acid, 0.3-2.0 mg L-1 and 0.23 mg L-1 for ferulic acid and 0.3-4.0 mg L-1 and 0.15 mg L-1 for rutin. GA was used as the standard, and the TAC of the fruit juices and honey samples as presented as GA equivalents (GAE). MF-CL was compared with DPPH and Folin-Ciocalteau (FC) methods.


Assuntos
Antioxidantes/química , Sucos de Frutas e Vegetais/análise , Mel/análise , Dispositivos Lab-On-A-Chip , Medições Luminescentes/métodos , Cobalto/química , Ácido Gálico/química , Peróxido de Hidrogênio/química , Medições Luminescentes/instrumentação , Bicarbonato de Sódio/química
18.
J Agric Food Chem ; 67(25): 6970-6977, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31150237

RESUMO

Huanglongbing (HLB), also known as citrus greening, is a bacterial disease that poses a devastating threat to the citrus industry worldwide. To manage this disease efficiently, we developed and characterized a ternary aqueous solution (TSOL) that contains zinc nitrate, urea, and hydrogen peroxide. We report that TSOL exhibits better antimicrobial activity than commercial bactericides for growers. X-ray fluorescence analysis demonstrates that zinc is delivered to citrus leaves, where the bacteria reside. FTIR and Raman spectroscopy, molecular dynamics simulations, and density functional theory calculations elucidate the solution structure of TSOL and reveal a water-mediated interaction between Zn2+ and H2O2, which may facilitate the generation of highly reactive hydroxyl radicals contributing to superior antimicrobial activity of TSOL. Our results not only suggest TSOL as a potent antimicrobial agent to suppress bacterial growth in HLB-infected trees, but also provide a structure-property relationship that explains the superior performance of TSOL.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Citrus/microbiologia , Nitratos/química , Nitratos/farmacologia , Doenças das Plantas/prevenção & controle , Rhizobiaceae/fisiologia , Compostos de Zinco/química , Compostos de Zinco/farmacologia , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/farmacologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Rhizobiaceae/efeitos dos fármacos , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Relação Estrutura-Atividade , Ureia/química , Ureia/farmacologia
19.
Plant Physiol Biochem ; 141: 398-406, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31228796

RESUMO

The fruticose epiphytic lichen Seirophora villosa, strictly associated with Juniperus shrublands in the Mediterranean basin, was used to investigate the role of hairiness on a lichen thallus, as a characteristic morphological trait. We evaluated the effect of hair removal on the physiological parameters of a set of samples, during desiccation and on exposure to different salt concentrations. Hairy thalli were less affected by salt, suggesting that during dehydration, the presence of hair protects the thallus from light irradiance, oxidative stresses and the lipid peroxidation generated by free radicals, and could offer passive, but selective, water control. Our results showed that hair could not only increase thallus surface and promote water absorption when availability is low, but could also repel the salt dissolved in water by activating a passive resistance mechanism, by preventing salt entering.


Assuntos
Clorofila A/química , Líquens/fisiologia , Estresse Oxidativo , Estresse Salino , Antioxidantes/química , Carotenoides/química , Clorófitas/fisiologia , Desidratação , Depuradores de Radicais Livres/química , Peróxido de Hidrogênio/química , Peroxidação de Lipídeos , Malondialdeído/química , Região do Mediterrâneo , Fotossíntese , Espécies Reativas de Oxigênio/química , Espectrometria de Fluorescência , Água/química
20.
Plant Physiol Biochem ; 141: 431-445, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31238253

RESUMO

S-adenosylmethionine synthetase (SAMS) catalyzes methionine and ATP to generate S-adenosyl-L-methionine (SAM). In plants, accumulating SAMS genes have been characterized and the majority of them are reported to participate in development and stress response. In this study, two putative SAMS genes (CsSAMS1 and CsSAMS2) were identified in cucumber (Cucumis Sativus L.). They displayed 95% similarity and had a high identity with their homologous of Arabidopsis thaliana and Nicotiana tabacum. The qRT-PCR test showed that CsSAMS1 was predominantly expressed in stem, male flower, and young fruit, whereas CsSAMS2 was preferentially accumulated in stem and female flower. And they displayed differential expression profiles under stimuli, including NaCl, ABA, SA, MeJA, drought and low temperature. To elucidate the function of cucumber SAMS, the full-length CDS of CsSAMS1 was cloned, and prokaryotic expression system and transgenic materials were constructed. Expressing CsSAMS1 in Escherichia coli BL21 (DE3) improved the growth of the engineered strain under salt stress. Overexpression of CsSAMS1 significantly increased MDA content, H2O2 content, and POD activity in transgenic lines under non-stress condition. Under salt stress, however, the MDA content of transgenic lines was lower than that of the wild type, the H2O2 content remained high, the polyamine and ACC synthesis in transgenic lines exhibited a CsSAMS1-expressed dependent way. Taken together, our results suggested that both CsSAMS1 and CsSAMS2 were involved in plant development and stress response, and a proper increase of expression level of CsSAMS1 in plants is benificial to improving salt tolerance.


Assuntos
Cucumis sativus/enzimologia , Cucumis sativus/fisiologia , Metionina Adenosiltransferase/metabolismo , Tolerância ao Sal , Antioxidantes/metabolismo , Arabidopsis/metabolismo , Secas , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/química , Metionina Adenosiltransferase/genética , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Poliaminas/química , Sais , Estresse Mecânico , Estresse Fisiológico/genética , Tabaco/metabolismo
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