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1.
Ecotoxicol Environ Saf ; 203: 111026, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888594

RESUMO

The detection of phenolic compounds, i.e. resorcinol (RC) catechol (CC) and hydroquinone (HQ) are important due to their extremely hazardous impact and poor environmental degradation. In this work, a novel and sensitive composite of electrochemically reduced graphene oxide-poly(Procion Red MX-5B)/gold nanoparticles modified glassy carbon electrode (GCE/ERGO-poly(PR)/AuNPs) was assembled for voltammetric detection of benzenediol isomers (RC, CC, and HQ). The nanocomposite displayed high peak currents towards the oxidation of RC, HQ, and CC compared to non-modified GCE. The peak-to-peak separations were 0.44 and 0.10 V for RC-CC and CC-HQ, respectively. The limit of detections were 53, 53, and 79 nM for HQ, CC, and RC with sensitivities of 4.61, 4.38, and 0.56 µA/µM (S/N = 3), respectively. The nanocomposite displayed adequate reproducibility, besides good stability and acceptable recoveries for wastewater and cosmetic samples analyses.


Assuntos
Compostos Azo/química , Derivados de Benzeno/análise , Técnicas Eletroquímicas/métodos , Ouro/química , Grafite/química , Nanocompostos/química , Poluentes Químicos da Água/análise , Cosméticos/química , Eletrodos , Nanopartículas Metálicas/química , Oxirredução , Reprodutibilidade dos Testes , Águas Residuárias/química
2.
Biosens Bioelectron ; 169: 112604, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32980805

RESUMO

Virus severely endangers human life and health, and the detection of viruses is essential for the prevention and treatment of associated diseases. Metal-organic framework (MOF), a novel hybrid porous material which is bridged by the metal clusters and organic linkers, has become a promising biosensor platform for virus detection due to its outstanding properties including high surface area, adjustable pore size, easy modification, etc. However, the MOF-based sensing platforms for virus detection are rarely summarized. This review systematically divided the detection platforms into nucleic acid and immunological (antigen and antibody) detection, and the underlying sensing mechanisms were interpreted. The nucleic acid sensing was discussed based on the properties of MOF (such as metal ion, functional group, geometry structure, size, porosity, stability, etc.), revealing the relationship between the sensing performance and properties of MOF. Moreover, antibodies sensing based on the fluorescence detection and antigens sensing based on molecular imprinting or electrochemical immunoassay were highlighted. Furthermore, the remaining challenges and future development of MOF for virus detection were further discussed and proposed. This review will provide valuable references for the construction of sophisticated sensing platform for the detection of viruses, especially the 2019 coronavirus.


Assuntos
Técnicas Biossensoriais/métodos , Estruturas Metalorgânicas/química , Viroses/virologia , Vírus/isolamento & purificação , Animais , Anticorpos Antivirais/análise , Antígenos Virais/análise , Técnicas Biossensoriais/instrumentação , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Humanos , Imunoensaio/instrumentação , Imunoensaio/métodos , Modelos Moleculares , Impressão Molecular/instrumentação , Impressão Molecular/métodos , Ácidos Nucleicos/análise , Espectrometria de Fluorescência/instrumentação , Espectrometria de Fluorescência/métodos , Viroses/diagnóstico
3.
PLoS One ; 15(8): e0238061, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32846429

RESUMO

The method of non-aqueous conductivity titration (NACT) of organic weak acids was applied to quickly and accurately determine the phenolic-hydroxyl and carboxyl-groups contents in humic acid. By varying the pH of the humic-acid sample, the concentration of the titrant, and the nitrogen-gas flow rate, the optimal titration conditions were determined to be a sample pH of 4, titrant concentration of 0.05 mol/L, and nitrogen-gas flow rate of 80 mL/min. Applying the detection method to p-hydroxybenzoic acid showed that its phenolic-hydroxyl content was 758.82±111.76 cmol/kg and carboxyl content was 744.44±51.11 cmol/kg. The theoretical phenolic-hydroxyl and carboxyl-groups contents of the p-hydroxybenzoic acid were 723.96 cmol/kg respectively, indicating that the method can accurately quantify the carboxyl and phenolic-hydroxyl groups in the sample. The NACT was used to measure the phenolic-hydroxyl and carboxyl-groups contents in humic acid quickly and accurately. In addition, 29 humic acid samples from 8 provinces of China covering the main humic-acid producing areas were collected and analyzed for acidic-groups content using the reported method.


Assuntos
Técnicas Eletroquímicas/métodos , Substâncias Húmicas/análise , China , Condutividade Elétrica , Eletrodos , Concentração de Íons de Hidrogênio , Hidroxibenzoatos/análise , Fenóis/química , Solo/química
4.
Ecotoxicol Environ Saf ; 204: 111004, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32768745

RESUMO

Consumption of seafood contaminated with ciguatoxins (CTXs) leads to a foodborne disease known as ciguatera. Primary producers of CTXs are epibenthic dinoflagellates of the genera Gambierdiscus and Fukuyoa. In this study, thirteen Gambierdiscus and Fukuyoa strains were cultured, harvested at exponential phase, and CTXs were extracted with an implemented rapid protocol. Microalgal extracts were obtained from pellets with a low cell abundance (20,000 cell/mL) and were then analyzed with magnetic bead (MB)-based immunosensing tools (colorimetric immunoassay and electrochemical immunosensor). It is the first time that these approaches are used to screen Gambierdiscus and Fukuyoa strains, providing not only a global indication of the presence of CTXs, but also the ability to discriminate between two series of congeners (CTX1B and CTX3C). Analysis of the microalgal extracts revealed the presence of CTXs in 11 out of 13 strains and provided new information about Gambierdiscus and Fukuyoa toxin profiles. The use of immunosensing tools in the analysis of microalgal extracts facilitates the elucidation of further knowledge regarding these dinoflagellate genera and can contribute to improved ciguatera risk assessment and management.


Assuntos
Ciguatoxinas/isolamento & purificação , Colorimetria/métodos , Dinoflagelados/química , Técnicas Eletroquímicas/métodos , Imunoensaio/métodos , Ciguatoxinas/classificação , Especificidade da Espécie
5.
Ecotoxicol Environ Saf ; 204: 111066, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32781344

RESUMO

In this study, an iron-doped metal-organic framework (MOF) Fe/ZIF-8 was synthesized from ZIF-8 at room temperature. Direct carbonization of Fe/ZIF-8 under a nitrogen atmosphere produced nanoporous nitrogen doped carbon nanoparticles decorated with Fe component (Fe/NC). The Fe/NC exhibited a large surface area (1221.185 m2 g-1) and narrow pore-size distribution (3-5 nm). The nanoporous Fe/NC components along with Nafion were used to modify a glassy carbon electrode for the electrochemical determination of chloramphenicol and metronidazole via linear sweep voltammetry. Under optimal conditions, the reduction peak currents (observed at -0.237 V and -0.071 V vs. Ag/AgCl) of these analytes increased linearly with increasing chloramphenicol and metronidazole concentrations in the range of 0.1-100 µM and 0.5-30 µM, with the detection limits estimated to be 31 nM and 165 nM, respectively. This result was attributed to the large surface area, porous structure, high nitrogen content, and as well as the electrocatalytic effect of Fe atoms embeded in the carbon support. The proposed sensor was used for chloramphenicol and metronidazole analysis in samples, providing satisfactory results.


Assuntos
Carbono/química , Cloranfenicol/análise , Técnicas Eletroquímicas/métodos , Ferro/química , Estruturas Metalorgânicas/química , Metronidazol/análise , Nitrogênio/química , Animais , Cloranfenicol/urina , Eletrodos , Humanos , Limite de Detecção , Metronidazol/urina , Leite/química , Nanoporos , Soluções Oftálmicas/química , Porosidade , Comprimidos/química
6.
ACS Sens ; 5(9): 2747-2752, 2020 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-32820626

RESUMO

With the current intense need for rapid and accurate detection of viruses due to COVID-19, we report on a platform technology that is well suited for this purpose, using intact measles virus for a demonstration. Cases of infection due to the measles virus are rapidly increasing, yet current diagnostic tools used to monitor for the virus rely on slow (>1 h) technologies. Here, we demonstrate the first biosensor capable of detecting the measles virus in minutes with no preprocessing steps. The key sensing element is an electrode coated with a self-assembled monolayer containing the measles antibody, immobilized through an N-heterocyclic carbene (NHC). The intact virus is detected by changes in resistance, giving a linear response to 10-100 µg/mL of the intact measles virus without the need to label or process the sample. The limit of detection is 6 µg/mL, which is at the lower limit of concentrations that can cause infections in primates. The NHC-based biosensors are shown to be superior to thiol-based systems, producing an approximately 10× larger response and significantly greater stability toward repeated measurements and long-term storage. This NHC-based biosensor thus represents an important development for both the rapid detection of the measles virus and as a platform technology for the detection of other biological targets of interest.


Assuntos
Anticorpos Imobilizados/imunologia , Benzimidazóis/química , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Vírus do Sarampo/isolamento & purificação , Anticorpos Imobilizados/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Ouro/química , Limite de Detecção , Vírus do Sarampo/imunologia
7.
Ecotoxicol Environ Saf ; 205: 111174, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32853867

RESUMO

Smelting wastewater is characterized with high concentration of toxic heavy metals and high acidity, which must be properly treated before discharge. Here, bioelectrochemical system (BES) coupled with thermoelectric generator (TEG) was first demonstrated to simultaneously treat organic wastewater and smelting wastewater by utilizing the simulated waste heat that was abundant in smelting factories. By modulating the input voltage generated from simulated waste heat via TEG to 0, 1.0 and 2.0 V, almost all the Cu2+, Cd2+ and Co2+ in smelting wastewater were sequentially recovered with a respective rate of 121.17, 158.20 and 193.87 mg L-1 d-1. Cu2+ was bioelectrochemically recovered as Cu0. While, Cd2+ and Co2+ were recovered by electrodeposition as Cd(OH)2, CdCO3 or Co(OH)2 on cathodic surface. High throughput sequencing analysis showed that the microbial community of anodic biofilm was greatly shifted after successive treatment by batch-mode. Desulfovibrio (17.00%), Megasphaera (11.81%), Geobacter (10.36%) and Propionibacterium (8.64%) were predominant genera in anodic biofilm enriched from activated sludge in BES before treatment. After successive treatment by batch-mode, Geobacter (34.76%), Microbacter (8.60%) and Desulfovibrio (5.33%) were shifted as the major genera. Economic analysis revealed that it was feasible to use TEG to substitute electrical grid energy to integrate with BES for wastewater treatment. In addition, literature review indicated that it was not uncommon for the coexistence of waste heat with typical pollutants (e.g. heavy metal ions and various biodegradation-resistant organic wastes) that could be treated by BES in different kinds of factories or geothermal sites. This study provides novel insights to expand the application potentials of BES by integrating with TEG to utilize widespread waste heat.


Assuntos
Reatores Biológicos/microbiologia , Técnicas Eletroquímicas/métodos , Metais Pesados/análise , Águas Residuárias/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Fontes de Energia Bioelétrica , Biofilmes/crescimento & desenvolvimento , Eletrodos , Geobacter/crescimento & desenvolvimento , Temperatura Alta , Esgotos/microbiologia
8.
Proc Natl Acad Sci U S A ; 117(29): 17260-17268, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32632007

RESUMO

Understanding how a network of interconnected neurons receives, stores, and processes information in the human brain is one of the outstanding scientific challenges of our time. The ability to reliably detect neuroelectric activities is essential to addressing this challenge. Optical recording using voltage-sensitive fluorescent probes has provided unprecedented flexibility for choosing regions of interest in recording neuronal activities. However, when recording at a high frame rate such as 500 to 1,000 Hz, fluorescence-based voltage sensors often suffer from photobleaching and phototoxicity, which limit the recording duration. Here, we report an approach called electrochromic optical recording (ECORE) that achieves label-free optical recording of spontaneous neuroelectrical activities. ECORE utilizes the electrochromism of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin films, whose optical absorption can be modulated by an applied voltage. Being based on optical reflection instead of fluorescence, ECORE offers the flexibility of an optical probe without suffering from photobleaching or phototoxicity. Using ECORE, we optically recorded spontaneous action potentials in cardiomyocytes, cultured hippocampal and dorsal root ganglion neurons, and brain slices. With minimal perturbation to cells, ECORE allows long-term optical recording over multiple days.


Assuntos
Eletrofisiologia/métodos , Neurônios/fisiologia , Poliestirenos , Tiofenos , Potenciais de Ação/fisiologia , Encéfalo/citologia , Encéfalo/fisiologia , Técnicas Eletroquímicas/métodos , Fenômenos Eletrofisiológicos , Corantes Fluorescentes , Gânglios Espinais/citologia , Gânglios Espinais/fisiologia , Humanos , Imagem Óptica , Óptica e Fotônica/métodos
9.
Chemosphere ; 255: 127013, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32679631

RESUMO

In order to obtain higher agricultural yields, the use of chemical substances has been increased to prevent the proliferation of pests, as well as ensuring durability in the storage of the food produced. Such substances are known as pesticides that may well present risks to human health and the environment. In the presence of metal ions, these substances can interact forming new species with different characteristics. Carbendazim (MBC) is an example of a harmful pesticide, which has atoms of nitrogen and oxygen in its structure that can form complexes with metal ions. Thus, in this work has studied the interaction between the copper (II) metal ion and carbendazim and its formation in natural water. The Cu-MBC complex showed a reduction peak of 0.007 V and an oxidation peak of 0.500 V, with characteristics of a quasi-reversible process under a glassy carbon electrode. By anodic stripping voltammetry, a different behavior was observed in the interaction of copper and carbendazim in ultrapure water and Billings dam water; however, it was possible to observe the complex in both samples. Carbendazim in the presence of the metal shows lower oxidation potential value, indicating the influence of the metal on the electrochemical response of the pesticide.


Assuntos
Benzimidazóis/química , Carbamatos/química , Cobre/química , Poluentes Químicos da Água/química , Carbono/química , Técnicas Eletroquímicas/métodos , Eletrodos , Oxirredução
10.
Nat Commun ; 11(1): 3743, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32719350

RESUMO

Ions are ubiquitous biological regulators playing a key role for vital processes in animals and plants. The combined detection of ion concentration and real-time monitoring of small variations with respect to the resting conditions is a multiscale functionality providing important information on health states. This multiscale functionality is still an open challenge for current ion sensing approaches. Here we show multiscale real-time and high-sensitivity ion detection with complementary organic electrochemical transistors amplifiers. The ion-sensing amplifier integrates in the same device both selective ion-to-electron transduction and local signal amplification demonstrating a sensitivity larger than 2300 mV V-1 dec-1, which overcomes the fundamental limit. It provides both ion detection over a range of five orders of magnitude and real-time monitoring of variations two orders of magnitude lower than the detected concentration, viz. multiscale ion detection. The approach is generally applicable to several transistor technologies and opens opportunities for multifunctional enhanced bioelectronics.


Assuntos
Amplificadores Eletrônicos , Sistemas Computacionais , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Íons/análise , Compostos Orgânicos/química , Transistores Eletrônicos , Eletricidade , Humanos , Íons/sangue , Potássio/análise
11.
Biosens Bioelectron ; 165: 112435, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32729548

RESUMO

COVID-19 is the shocking viral pandemics of this year which affected the health, economy, communications, and all aspects of social activities all over the world. Early diagnosis of this viral disease is very important since it can prevent lots of mortalities and care consumption. The functional similarities between COVID-19 and COVID-2 in inducing acute respiratory syndrome lightened our mind to find a diagnostic mechanism based on early traces of mitochondrial ROS overproduction as lung cells' dysfunctions induced by the virus. We designed a simple electrochemical sensor to selectively detect the intensity of ROS in the sputum sample (with a volume of less than 500 µl). Comparing the results of the sensor with clinical diagnostics of more than 140 normal and involved cases resulted in a response calibration with accuracy and sensitivity both 97%. Testing the sensor in more than 4 hospitals shed promising lights in ROS based real-time tracing of COVID-19 from the sputum sample.


Assuntos
Betacoronavirus/isolamento & purificação , Técnicas Biossensoriais/métodos , Infecções por Coronavirus/diagnóstico , Técnicas Eletroquímicas/métodos , Pneumonia Viral/diagnóstico , Espécies Reativas de Oxigênio/análise , Escarro/virologia , Adulto , Idoso , Técnicas Biossensoriais/instrumentação , Infecções por Coronavirus/virologia , Diagnóstico Precoce , Técnicas Eletroquímicas/instrumentação , Desenho de Equipamento , Feminino , Humanos , Pulmão/química , Pulmão/virologia , Masculino , Pessoa de Meia-Idade , Pandemias , Pneumonia Viral/virologia , Sensibilidade e Especificidade , Escarro/química , Adulto Jovem
12.
Food Chem ; 332: 127409, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32615388

RESUMO

This work reports a new method to evaluate the antioxidant capacity of infusions and beverages, based on superoxide radicals. Radicals produced by the enzymatic reaction between acetylcholinesterase and hypoxanthine oxidized antioxidant molecules present in commercially available samples or standard solutions, which was monitored by means of cyclic voltammetry using a carbon paste electrode. The Trolox equivalent antioxidant capacity (TEAC) of red wine, coffee and green tea determined using this method were: (1.20 ± 0.06), (0.90 ± 0.02), and (0.65 ± 0.02), respectively. This method suggested TEACred wine > TEACcoffee > TEACgreen tea, which is the same as DPPH, spectrophotometric method. However, the electrochemical one proposed here is rapid and simple.


Assuntos
Antioxidantes/química , Bebidas/análise , Técnicas Eletroquímicas/métodos , Superóxidos/química , Antioxidantes/metabolismo , Café/química , Eletrodos , Concentração de Íons de Hidrogênio , Hipoxantina/química , Hipoxantina/metabolismo , Oxirredução , Superóxidos/metabolismo , Chá/química , Vinho/análise , Xantina Oxidase/metabolismo
13.
Artigo em Inglês | MEDLINE | ID: mdl-32615055

RESUMO

The effect of the presence of minerals in natural soil polluted with lead (II) was investigated to verify the efficiency of the electrokinetic remediation method. Natural soil "Sebkha of Oran" containing high calcite minerals and characterized by high salinity was used in experimental studies. This study investigates the effects of alkaline soil pH conditions on the transport and removal of lead by the electrokinetic treatment. XRD analyses were performed on the soil sample before and after electrokinetic treatment to determine any changes in mineral phases. Mathematical models using experimental data are developed to describe the mobility and diffusion coefficient of lead ions through the soil. Mathematical models were generated based on the physicochemical parameters characterizing the movement of cations and anions.


Assuntos
Técnicas Eletroquímicas/métodos , Recuperação e Remediação Ambiental/métodos , Chumbo/análise , Modelos Teóricos , Poluentes do Solo/análise , Solo/química , Ânions , Cátions , Minerais/química
14.
Chemosphere ; 260: 127587, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32663673

RESUMO

In this work, a three-dimension grapnene-PbO2 (3DG-PbO2) composite anode was prepared using coelectrodeposition technology for electrocatalytic oxidation of perfluorooctane sulfonate (PFOS). The effect of 3DG on the surface morphology, structure and electrocatalytic activity of PbO2 electrode was investigated. The results indicated that the 3DG-PbO2-0.08 anode (3DG concentration in electrodeposition solution was 0.08 g L-1) possessed the best electrocatalytic activity due to its stronger ·OH radicals generation capacity, more active sites and smaller charge-transfer resistance. The degradation rate constant of PFOS on 3DG-PbO2-0.08 anode was 2.33 times than that of pure PbO2 anode. Additionally, the by-products formed in electrocatalytic degradation of PFOS were identified and a PFOS degradation pathway was proposed accordingly, which was dominated by the dissociation of -CF2- groups via the attack of ·OH radicals. Finally, the toxicity evolution of degradation solution was examined to evaluate the ecological risk of electrocatalytic oxidation of PFOS by acute toxicity assays to zebrafish embryos.


Assuntos
Ácidos Alcanossulfônicos/análise , Técnicas Eletroquímicas/métodos , Fluorcarbonetos/análise , Grafite/química , Chumbo/química , Nanocompostos/química , Óxidos/química , Titânio/química , Poluentes Químicos da Água/análise , Ácidos Alcanossulfônicos/toxicidade , Animais , Eletrodos , Galvanoplastia , Embrião não Mamífero/efeitos dos fármacos , Fluorcarbonetos/toxicidade , Oxirredução , Poluentes Químicos da Água/toxicidade , Peixe-Zebra
15.
Food Chem ; 333: 127495, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32663747

RESUMO

Various pesticides employed in modern agriculture result in large amounts of pesticide residues in agricultural production, greatly threatening human health. Herein, we report a facile approach to fabricate a reduced graphene oxide/cyclodextrin modified glassy carbon electrode (rGO/CD/GCE) for the sensitive electrochemical sensing of imidacloprid (IDP). Three different modified electrodes using CDs (α-, ß-, γ-CD) were fabricated, and their electrochemical performance was further studied. The results demonstrate that α-CD possesses the best signal amplification for IDP. Compared with wet-chemical synthesis of rGO/CDs (W-rGO/CDs), the electrochemical synthesis of rGO/CDs (E-rGO/CDs) produced sensors that showed better performance for IDP sensing. Taking advantage of prepared E-rGO/α-CD nanocomposite, the fabricated sensor offered a low detection limit (0.02 µM) with a wider linear range (0.5-40 µM) and long-term stability. The new sensor was successfully applied for the detection of IDP in brown rice, providing a new technique for efficient and convenient monitoring of pesticide residues in food.


Assuntos
Ciclodextrinas/química , Técnicas Eletroquímicas/métodos , Grafite/química , Inseticidas/análise , Neonicotinoides/análise , Nitrocompostos/análise , Oryza/química , Carbono/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Contaminação de Alimentos/análise , Nanocompostos/química , Oxirredução , Sementes/química , Sensibilidade e Especificidade
16.
Food Chem ; 333: 127524, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32679418

RESUMO

Semicarbazide (SEM) is a protein-bound nitrofurazone metabolite that is detrimental to human health. Therefore, to ensure food safety, it is necessary to detect SEM in food samples. To this end, we developed a novel electrochemical sensor to detect SEM by using a molecularly imprinted polymer (MIP) as the recognition element. Computer-aided molecular modelling was performed to guide the synthesis of the MIP, and subsequently, MIP/carboxylated single-walled carbon-nanotubes/chitosan (MIP/SWNTs-COOH/CS) was prepared as the sensing platform to develop the electrochemical sensor. The linear range of the sensor was 0.04-7.6 ng mL-1, with a detection limit of 0.025 ng mL-1. The sensor was successfully applied to detect SEM in four different real samples, with recoveries ranging from 83.16% to 93.40%. The results indicated that the fabricated electrochemical sensor can be widely applied to detect SEM in the environment and in agri-food products.


Assuntos
Quitosana/química , Técnicas Eletroquímicas/métodos , Impressão Molecular , Nanotubos de Carbono/química , Semicarbazidas/análise , Eletrodos , Mel/análise , Humanos , Limite de Detecção , Carne/análise , Polímeros/química , Reprodutibilidade dos Testes , Alimentos Marinhos/análise
17.
Ecotoxicol Environ Saf ; 201: 110862, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32559691

RESUMO

In this study, a novel electrochemical sensor based on self-assembled rod-like lanthanum hydroxide-oxidized multi-walled carbon nanotubes (La(OH)3-OxMWCNTs) nanocomposite was developed for sensitive determination of p-nitrophenol (p-NP). The La(OH)3-OxMWCNTs nanocomposite with an interpenetrating networks structure was characterized by field emission electron microscope (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, Raman spectra and X-ray photoelectron spectroscopy (XPS). The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were performed to study the electrochemical behaviors of La(OH)3-OxMWCNTs modified glassy carbon electrode (La(OH)3-OxMWCNTs/GCE). The La(OH)3-OxMWCNTs/GCE was used for sensitive determination of p-NP by CV and linear sweep voltammetry (LSV). Under the optimum conditions, the peak currents of LSV versus the concentrations of p-NP in the range 1.0-30.0 µmol L-1 showed a good linear relationship (R2=0.9971), and the limit of detection (LOD) was calculated to be 0.27 µmol L-1 (signal-to-noise ratio of 3, S/N=3). The recoveries of p-NP in real samples of industrial wastewater and Xiangjiang water at La(OH)3-OxMWCNTs/GCE were in the range of 95.62-110.75% with relative standard deviation (RSD) in the range of 1.65-3.85%. The intra-day and inter-day precisions were estimated to be less than 2.76% (n= 5), indicating that La(OH)3-OxMWCNTs/GCE possessed highly stability. In addition, La(OH)3-OxMWCNTs/GCE sensor showed good anti-interference ability for determination of p-NP in aqueous mixtures containing high concentrations of inorganic and organic interferents, and a decrease of oxidation peak currents by less than 3.57% relative to the initial levels indicated it possessed excellent selectivity. Therefore, La(OH)3-OxMWCNTs/GCE could be used as a fast, selective and sensitive electrochemical sensor platform for the selective determination and quantification of aqueous p-NP.


Assuntos
Técnicas Eletroquímicas/métodos , Lantânio/química , Nanocompostos/química , Nanotubos de Carbono/química , Nitrofenóis/análise , Eletrodos , Limite de Detecção , Oxirredução
18.
Ecotoxicol Environ Saf ; 201: 110872, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32559693

RESUMO

Based on a hybrid carbon nanotube composite, a novel electrochemical sensor with high sensitivity and selectivity was designed for the simultaneous determination of dopamine (DA) and uric acid (UA). The hybrid carbon nanotube composite was prepared by ultrasonic assembly of carboxylated multi-walled carbon nanotube (MWCNT-COOH) and hydroxylated single-walled carbon nanotube (SWCNT-OH). And the hybrid (MWCNT-COOH/SWCNT-OH) composite was characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical performances of MWCNT-COOH/SWCNT-OH composite modified glassy carbon electrode (MWCNT-COOH/SWCNT-OH/GCE) were analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under the optimum experimental conditions, the as-prepared sensor showed high sensitivity and selectivity for DA and UA. The calibration curves obtained were linear for the currents versus DA and UA concentrations in the range 2-150 µM, and limits of detection (LODs) were calculated to be 0.37 µM and 0.61 µM (signal-to-noise ratio of 3, S/N = 3), respectively. The recoveries of DA and UA in bovine serum samples at MWCNT-COOH/SWCNT-OH/GCE were in the range 96.18-105.02%, and relative standard deviations (RSDs) were 3.34-7.27%. The proposed electrochemical sensor showed good anti-interference ability, excellent reproducibility and stability, as well as high selectivity, which might provide a promising platform for determination of DA and UA.


Assuntos
Dopamina/análise , Técnicas Eletroquímicas/métodos , Nanotubos de Carbono/química , Ácido Úrico/análise , Animais , Carbono , Bovinos , Dopamina/sangue , Eletrodos , Limite de Detecção , Nanotubos de Carbono/ultraestrutura , Reprodutibilidade dos Testes , Ácido Úrico/sangue
19.
Nat Commun ; 11(1): 2706, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32483217

RESUMO

Aldehyde is one of most synthetically versatile functional groups and can participate in numerous chemical transformations. While a variety of simple aromatic aldehydes are commercially available, those with a more complex substitution pattern are often difficult to obtain. Benzylic oxygenation of methylarenes is a highly attractive method for aldehyde synthesis as the starting materials are easy to obtain and handle. However, regioselective oxidation of functionalized methylarenes, especially those that contain heterocyclic moieties, to aromatic aldehydes remains a significant challenge. Here we show an efficient electrochemical method that achieves site-selective electrooxidation of methyl benzoheterocycles to aromatic acetals without using chemical oxidants or transition-metal catalysts. The acetals can be converted to the corresponding aldehydes through hydrolysis in one-pot or in a separate step. The synthetic utility of our method is highlighted by its application to the efficient preparation of the antihypertensive drug telmisartan.


Assuntos
Acetais/química , Aldeídos/química , Técnicas Eletroquímicas/métodos , Hidrocarbonetos Aromáticos/química , Modelos Químicos , Acetais/síntese química , Aldeídos/síntese química , Amidinas/química , Benzimidazóis/química , Catálise , Hidrocarbonetos Aromáticos/síntese química , Hidrólise , Estrutura Molecular , Oxidantes/química , Oxirredução
20.
Ecotoxicol Environ Saf ; 201: 110858, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32563161

RESUMO

This work presents the research on the treatment of an anthraquinone derivatives of disperse dye Blue SI from aqueous solution using aluminium for the optimization of operational parameters like pH, current density, addition of electrolyte, contact time for the color removal efficiency (CRE) and the results are compared with the performance of copper electrodes in electrocoagulation (EC). The parameters for maximum CRE was found with Al at current density 40 Am-2, time 10 min at pH 7, and for Cu at 60 Am-2 15 min, at pH 6 were optimized. The characterization of the treated water using HPLC, MS studies revealed intermediate compounds. From the XPS analysis of the sludge obtained, the mechanism of EC was deduced. Treated aqueous solution was studied for its phytotoxicity with Vigna radiata and ecotoxicity studies were conducted on Artemia salina to study the toxicity effect of the intermediatory products in the treated dye solution. Blue SI dye aqueous solution treated with aluminium electrodes shows no or lesser toxicity in plants as well as in ecotoxic study compared with copper electrodes.


Assuntos
Alumínio/química , Antraquinonas/análise , Cobre/química , Técnicas Eletroquímicas/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Animais , Antraquinonas/química , Antraquinonas/toxicidade , Artemia/efeitos dos fármacos , Eletrodos , Floculação , Concentração de Íons de Hidrogênio , Esgotos/química , Vigna/efeitos dos fármacos , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade
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