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1.
Food Chem ; 368: 130811, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34399177

RESUMO

Since excessive use of synthetic dyes has negative effects on human health, their determination in foodstuff is necessary. A sensitive sensor was developed based on copper BTC metal-organic framework (Cu-BTC MOF) and 1-ethyl-3-methylimidazolium chloride as an ionic liquid (IL) in an attempt to modify the carbon paste electrode and to improve the active surface area and electric conductivity so that electron transfer is faster for electro analysis. For the first time, high sensitivity, excellent conductivity, and appropriate selectivity of the electrochemical sensor have been evaluated as a new study for simultaneous determination of tartrazine, patent blue V, acid violet 7 and ponceau 4R. Excellent sensing performance of the proposed electrode was confirmed for patent blue V as an outstanding sensor, according to the low limit of detection of 0.07 µM, with a wide linear concentration range of 0.08 to 900 µM and reasonable recovery. In order to characterize the electrochemical behavior of electrode, cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy are used. Various techniques such as scanning electron microscopy (SEM) with energy dispersive X-Ray analysis (EDX), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) are employed to verify the structure of copper BTC metal-organic framework. The results revealed close packing of hierarchically porous nanoparticles and crystal structure of Cu-BTC MOF, with the edge of each particle around 20-37 nm. The analytical performance of the suggested electrochemical sensor is acceptable in foodstuffs such as jellies, condiments, soft drinks, and candies.


Assuntos
Líquidos Iônicos , Estruturas Metalorgânicas , Compostos Azo , Cobre , Técnicas Eletroquímicas , Eletroquímica , Eletrodos , Humanos , Naftalenossulfonatos , Corantes de Rosanilina , Tartrazina
2.
J Hazard Mater ; 421: 126740, 2022 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-34333409

RESUMO

Azo dye pollution has become a worldwide issue, and the current treatment methods can hardly meet the expected emission standards. Microbial electrochemical systems (MESs) show promising applications for decolorization, but their performance critically depends on the microorganisms. Electrode modification is an interesting method of improving decolorization performance. However, the mechanisms of how the modification can affect microbial communities and the decolorization process remain unclear. Here, a modified anode with polyaniline (PANI) and graphene was fabricated via electro-deposition. Consequently, the highest decolorization efficiency was obtained. The Congo red (CR) decolorization rate of the MESs with the PANI/graphene-modified electrode (PG) reached 90% at 54 h. By contrast, the CR decolorization rates of the MESs with the PANI-modified electrode (P) and those of the MESs with the unmodified electrode (C) only reached 68% and 79%, respectively. Results of the microbial community analysis showed abundant Methanobrevibacter arboriphilus in PG (11%), which was 5.5 times that in C (2%) at 18 h. This phenomenon may be related to the rapid decolorization. The upregulated metabolism pathways, including arginine and proline metabolism, purine metabolism, arginine biosynthesis, and riboflavin metabolism, provided more electron shuttles and redox mediators that facilitated the extracellular electron transfer. Therefore, the PG-modified electrode facilitated the decolorization by altering certain metabolic pathways. This study can help to improve the guideline on the potential application of MESs for wastewater treatment.


Assuntos
Compostos Azo , Grafite , Compostos de Anilina , Corantes , Eletrodos , Águas Residuárias
3.
Food Chem ; 368: 130829, 2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-34411858

RESUMO

In this paper, an innovative method for the sensitive detection of new coccine using N, P-doped carbon quantum dots (N,P-CQDs) as fluorescent nanosensor is reported for the first time. The sensing mechanism is based on the fluorescence quenching of N,P-CQDs by new coccine through inner filter effect (IFE). N,P-CQDs were prepared by simple hydrothermal treatment of citric acid, phosphoric acid and ethylenediamine. Under the optimal conditions, the new coccine has two good linear responses in the concentration range of 0.2-100 and 100-200 µM, and the detection limits are as low as 24.8 and 9.4 nM, respectively. Our developed nanosensor has been successfully used for the determination of new coccine in food samples with good precision and high accuracy. This work highlights the economic, rapid, simple, selective and ultra-sensitive for new coccine detection, and opens up a new way for the monitoring of new coccine in actual food samples.


Assuntos
Pontos Quânticos , Compostos Azo , Carbono , Naftalenossulfonatos , Nitrogênio , Fósforo , Espectrometria de Fluorescência
4.
Chemosphere ; 286(Pt 2): 131779, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34364225

RESUMO

Anaerobic decolorization of azo dye in sulfate-containing wastewater has been regarded as an economical and effective method, but it is generally limited by the high concentration of azo dye and accumulation of toxic intermediates. To address this problem, Fe3O4 was added to one of the anaerobic reactors to investigate the effects on system performances. Results showed that AO7 removal rate, COD removal rate, and sulfate reduction were enhanced with the addition of Fe3O4 under various influent AO7 concentrations (153 mgCOD/L - 1787 mgCOD/L). According to the proposed pathway for the degradation of AO7, more intermediates (2-hydroxy-1,4-naphthoquinone, phthalide, 4-methylphenol) were produced in the presence of Fe3O4. The electron transfer capacity of sludge was also increased since Fe3O4 could stimulate to secrete humic acid-like organics in EPS. Microbial analysis showed that iron-reducing bacteria like Clostridium and Geobacter were also enriched, which were capable of azo dye and aromatic compounds degradation.


Assuntos
Compostos Azo , Microbiota , Anaerobiose , Reatores Biológicos , Corantes , Elétrons , Óxidos , Sulfatos
5.
Chemosphere ; 286(Pt 2): 131792, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34388875

RESUMO

Manganese (II) ions (Mn(II)) catalyse the oxidative degradation of Calmagite (CAL, 2-hydroxy-1-(2-hydroxy-5methylphenylazo)-4-naphthalenesulfonic acid) at room temperature using added and in situ generated hydrogen peroxide (H2O2), using 1,2-dihydroxybenzene-3,5-disulfonate, disodium salt and monohydrate (Tiron) as the co-catalyst for the in situ generation of H2O2. The percentage of CAL degradation with the in situ generated H2O2 was 91.1 % after 30 min which is lower than that in the added H2O2/Mn(II) system (96.0 %). A one-eighth-lives method was applied to investigate the kinetic parameters in the added H2O2 system, with and without Mn(II), involving phosphate, carbonate, and two biological buffers at different pHs. Percarbonate (HCO4-) was found to be the main reactive species for CAL degradation in the added H2O2 system buffered by carbonate in the absence of Mn(II). Manganese (IV) = O (Mn(IV) = O) and manganese(V) = O (Mn(V) = O) are the main reactive species in the added H2O2/Mn(II) system buffered by carbonate and non-carbonate buffers respectively. pH 8.5 was the optimum pH for CAL degradation when buffered by carbonate, while pH 10.0 is the best pH for the systems not using carbonate buffer. Using a high performance liquid chromatography/electrospray ionisation mass spectrometer (HPLC/ESI-MS), the degradation intermediates of CAL were identified as 1-amino-2-naphthol-4-sulfonate ion, 1-amino-2-naphthol-4-sulfinic ion, 1-amino-2-naphthol, and 1-nitroso-2-naphthol.


Assuntos
Peróxido de Hidrogênio , Manganês , Compostos Azo , Catálise , Cinética , Estresse Oxidativo
6.
Chemosphere ; 286(Pt 3): 131832, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34399265

RESUMO

Vast efforts are directed today toward the development of efficient, green methods for the degradation of toxic compounds, especially those that are water-soluble. Though Fenton reactions are commonly used in wastewater treatment, their mechanisms and the active species involved remain obscure due to their mechanistic complexity. In this work, the mechanism of an electro-Fenton reaction, in which a FeLaO3 catalyst was entrapped in a sol-gel matrix, was studied in the presence of azo dyes as the model for toxic compounds. Increased knowledge about this important mechanism will confer greater control over related processes and enable a more efficient and green degradation method. DFT calculations showed that in the presence of Fe(IV), OH are formed under acidic conditions and that both the iron and hydroxyl species function as oxidation reagents in the degradation process. The structure of the formed Fe(IV) embedded in the solid matrix was not the typical tetravalent structure. Entrapment in the sol-gel matrix stabilized the catalyst, enhanced its efficiency and enabled it to be recycled. Sol-gel matrices constitute a simple method for the degradation of stable and toxic compounds under extreme pH conditions. The findings of this study are highly significant for the treatment of typically acidic wastewaters.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Compostos Azo , Catálise , Peróxido de Hidrogênio , Oxirredução , Poluentes Químicos da Água/análise
7.
Chemosphere ; 286(Pt 3): 131914, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34418664

RESUMO

Reactive dyes are extensively used in a plethora of industries, which in turn release toxic wastes into the environment. The textile dye waste remediation is crucial as it may contain several toxic elements. The utilization of bacterial consortium for bioremediation has acquired consideration, over the utilization of single strains. In this study, a microbial consortium containing three bacterial sp. (Bacillus subtilis, Brevibacillus borstelensis and Bacillus firmus) was tested for its degrading ability of the textile RR 170 dye. The bacterial consortium degraded the dye effectively at lower concentrations and the efficiency decreased as the dye concentration increased. SEM analysis revealed that, with dye treatment, the consortium appeared as tightly packed clumps with rough cell surface and were able to produce EPS and biofilms. EPS production was higher at 40 mg/l, 100 mg/l and 200 mg/l of the dye treatment conditions. Interestingly, the maximum biofilm formation was observed only at 40 µg/ml of the dye treatment, which indicates that RR 170 dye concentration affects the biofilm formation independent of EPS levels. The UV-vis spectroscopy, HPLC, FTIR and 2D-FTIR analyses confirmed the decolorization and biodegradation of RR 170 dye by the bacterial consortium. Toxicological studies performed with the dye and their degraded products in Allium cepa root cells revealed that, whereas the RR 170 dye induced genotoxic stress, the degraded dye products showed no significant genotoxic effects in root cells. Together, the investigated bacterial consortium decolorized and degraded the RR 170 dye resulting in metabolites that are non-toxic to the living cells.


Assuntos
Brevibacillus , Corantes , Compostos Azo , Biodegradação Ambiental , Biofilmes , Indústria Têxtil , Águas Residuárias
8.
Chemosphere ; 286(Pt 1): 131528, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34303051

RESUMO

The concept of natural organic matter of anthropogenic origin is introduced and its characteristics and interaction with chemical pollutants are investigated by adopting several distinct analytic methodologies. Scanning electron microscopy indicates that the used sample of anthropogenic organic matter (AOM) has an amphiphilic nature, which allows its supramolecular organization in water. Fourier transform infrared spectroscopy, in turn, gives a clear indication about the presence of polysaccharide markers, lipidic and amidic fractions, and suggests the absence of free organic acid. AOM sample and AOM mixed with dye sample were examined by the three-dimensional excitation-emission matrix fluorescence spectra and the nuclear magnetic resonance mono-dimensional spectra. The results highlighted the interactions occurring between the AOM and the reactive dye, selected as a representative chemical pollutant. Electron Spin Resonance confirms that the used AOM is able to completely include the dye in its structure. Overall, the obtained results indicate that the fate, transport, and toxicity of pollutants in the environment can be drastically influenced by the presence of AOM.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Compostos Azo , Naftalenos , Poluentes Químicos da Água/análise
9.
Talanta ; 237: 122986, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34736705

RESUMO

A highly sensitive cationic polyfluorinated azobenzene/reduced graphene oxide (C3F7-azo+/RGO) nanocomposite electrochemical sensor for simultaneous detection of dopamine (DA), ascorbic acid (AA) and uric acid (UA) was successfully synthesized using a facile exfoliation/restacking method. The nanocomposite is self-assembled from oppositely charged graphene oxide nanosheets (GO) and polyfluorinated azobenzene cations (C3F7-azo+), and then obtained by electrochemical reduction. The structure and electrochemical properties were characterized by X-ray diffraction (XRD), energy dispersive spectrometer analysis (EDS), transmission electron microscope (TEM) and scanning electron microscope (SEM). The electrochemical property of C3F7-azo+/RGO was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). It can be clearly seen from experimental results that C3F7-azo+/RGO-modified electrode (C3F7-azo+/RGO/GCE) can detect DA, AA and UA simultaneously, and has good stability and anti-interference performance. The detection limits are 65 nM, 8 nM and 11 nM for DA, AA and UA in the ranges 57.28-134.28 µM, 0.04-6.01 µM, 9.23-23.45 µM, respectively.


Assuntos
Grafite , Ácido Úrico , Ácido Ascórbico , Compostos Azo , Cátions , Dopamina , Técnicas Eletroquímicas , Eletrodos
10.
J Environ Manage ; 301: 113924, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34731947

RESUMO

The present paper aimed to investigate the roles of quinones contained in wastewater and the enhanced effects on microbial fuel cells (MFCs) under different redox conditions. The feasibility of using wastewater rich in quinones to act as co-substrate and redox mediators (RMs) library to strengthen the synergistic removal of azo dye in MFCs was evaluated. The results demonstrated that quinones achieved enhanced effects on electricity generation and COD removal of MFC better at higher current intensity. The addition of pure quinone decreased electron transfer resistance (Rct) of MFCs from 4.76 Ω to 2.13 Ω under 1000 Ω resistance and 1.16 Ω-0.75 Ω under 50 Ω resistance. Meanwhile, higher coulombic efficiency was achieved. Compared with sodium acetate, using quinone-rich traditional Chinese medicine (TCM) wastewater as the co-substrate enhanced the synergistic removal of reactive red 2 (RR2) in MFCs from 79.58% to 92.45% during 24 h. RR2 was also degraded more thoroughly due to the accelerated electron transfer process mediated by RMs. Microbial community analysis demonstrated that the presence of quinone in TCM wastewater can enrich different exoelectrogens under varied redox conditions and thus influenced the enhanced effects on MFC. Metagenomic functional prediction results further indicated that the abundance of functional genes involved in carbohydrate metabolism, membrane transport metabolism, biofilm formation, and stress tolerance increased significantly in presence of RMs. Redundancy analyses revealed that RMs addition was the more important factor driving the variation of the microorganism community. This study revealed the potential effect of quinones as redox mediators on the bioelectrochemical system for pollutants removal.


Assuntos
Fontes de Energia Bioelétrica , Compostos Azo , Eletricidade , Eletrodos , Oxirredução , Quinonas , Águas Residuárias
11.
Int J Mol Sci ; 22(19)2021 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-34639104

RESUMO

The interactions of two conformers of newly synthesized photoswitchable azobenzene analogue of methotrexate, called Phototrexate, with two cavitand derivatives, have been investigated in dimethyl sulfoxide medium. Photoluminescence methods have been applied to determine the complex stabilities and the related enthalpy and entropy changes associated to the complex formation around room temperature. Results show opposite temperature dependence of complex stabilities. The structure of the upper rims of the host molecules and the reordered solvent structure were identified as the background of the opposite tendencies of temperature dependence at molecular level. These results can support the therapeutic application of the photoswitchable phototrexate, because the formation of inclusion complexes is a promising method to regulate the pharmacokinetics of drug molecules.


Assuntos
Compostos Azo/química , Éteres Cíclicos/química , Metotrexato/química , Resorcinóis/química , Compostos Azo/metabolismo , Éteres Cíclicos/metabolismo , Isomerismo , Metotrexato/metabolismo , Modelos Moleculares , Estrutura Molecular , Resorcinóis/metabolismo , Temperatura , Termodinâmica
13.
Se Pu ; 39(9): 998-1005, 2021 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-34486839

RESUMO

In this work, a polymer precursor was first synthesized using p-terphenyl (TP) and terephthaloyl chloride (TC) as monomers. Then, cross-linking was realized by means of a Schiff base reaction with melamine (MA) as a modifier to obtain an amine-functionalized porous organic polymer TP-TC-MA. The synthesized polymers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and point of zero charge (pHpzc) measurements, as well as on the basis of nitrogen adsorption-desorption isotherms. Adsorption experiments were carried out to evaluate the adsorption properties of TP-TC-MA for methyl orange (MO), a typical anionic azo dye that has widespread industrial application. The amount of MO adsorbed on TP-TC-MA was evaluated by ultraviolet-visible (UV-Vis) spectroscopy at a wavelength of 463 nm. Microscopic analysis revealed that the as-synthesized polymer had an aggregated particle-shaped structure. XRD spectra confirmed that TP-TC-MA was an amorphous polymer, consistent with the results of high-resolution TEM experiments. The Brunauer-Emmett-Teller (BET) specific surface area and total pore volume of TP-TC-MA were determined as 708.5 m 2/g and 0.556 cm3/g, respectively. The measured pHpzc of TP-TC-MA was 4.0, probably because of the abundant nitrogen-containing groups provided by MA. The factors affecting adsorption, such as pH, adsorbent dosage, contact time, initial pollutant concentration, and ionic strength, were investigated. Because of the protonation of the N-atom in TP-TC-MA, the pH had a strong impact on the adsorption of MO. The removal efficiency could be maximized at the optimized pH of 3.0. The adsorption equilibrium isotherm, measured at 25 ℃ and a concentration of 50-500 mg/L, showed that the MO adsorption over TP-TC-MA followed the Langmuir isotherm, with a maximum adsorption capacity of 156.3 mg/g. The modeling of the experimental adsorption data was consistent with the pseudo-second-order kinetic model, which indicated fast adsorption and chemisorption as the dominant mechanism. With increasing ionic strength, the adsorption of MO slightly decreased, suggesting a partial antagonistic ion effect. Results of the selectivity study revealed that TP-TC-MA was more selective toward MO than methylene blue (MB), which indicated that electrostatic interactions played a significant role during the adsorption progress. Five adsorption-desorption cycles showed that TP-TC-MA could be regenerated without significant deterioration of its adsorption efficiency, indicating that it has good stability and reusability. The observed adsorption performance indicated that this MA-modified porous organic polymer offers prospects for further research and application in the treatment of dye-containing wastewaters.


Assuntos
Polímeros , Poluentes Químicos da Água , Adsorção , Compostos Azo , Concentração de Íons de Hidrogênio , Cinética , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Triazinas , Poluentes Químicos da Água/análise
14.
J Phys Chem B ; 125(40): 11197-11207, 2021 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-34586822

RESUMO

The DNA interaction with cis-isomers of photosensitive azobenzene-containing surfactants was studied by both experimental methods and computer simulation. It was shown that before the organization of micelles, such surfactants in the cis-conformation form associates of only a single type with a disordered orientation of molecules. In contrast, for trans-isomers, there exist two types of associates with head-to-head or head-to-tail orientations of molecules in dependence on salt concentration in a solution. The comparison of cis- and trans-isomer binding to DNA and the influence of salt concentration on the formation of their complexes with DNA were studied. It was shown that cis-isomers interact with phosphate groups of DNA and that their molecules were also located along the minor groove of DNA.


Assuntos
Cloreto de Sódio , Tensoativos , Compostos Azo , Simulação por Computador , DNA
15.
J Org Chem ; 86(19): 13454-13464, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34515479

RESUMO

A new type of diazo compounds, namely, CH-diazomethane sulfonamides (generated in situ from readily available α-acetyl-α-diazomethane sulfonamides), was employed in a 1,3-dipolar cycloaddition reaction with imines (also formed in situ from primary amines and aldehydes). The reaction gave hitherto undescribed 1,5-disubstituted 1,2,3-triazoline-4-sulfonamides, which were obtained in good to excellent yields with complete trans diastereoselectivity. These new sulfonamides based on the nonaromatic 1,2,3-triazoline core are rather attractive from a medicinal chemistry standpoint in light of the strong emphasis recently put on the nonflat, more saturated (higher Fsp3) scaffolds for lead-generation libraries. The oxidative aromatization of 1,2,3-triazoline-4-sulfonamides by manganese(IV) oxide gave nearly quantitative yields of 1,2,3-triazole-4-sulfonamides, of which only two examples have been reported in the literature.


Assuntos
Iminas , Sulfonamidas , Aldeídos , Compostos Azo , Estrutura Molecular
16.
G3 (Bethesda) ; 11(10)2021 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-34568919

RESUMO

Shewanella decolorationis are Gram-negative γ-Proteobacteria with environmental bioremediation potential because they can perform anaerobic respiration using various types of pollutants as terminal electron acceptors. So far, three isolated and cultured strains of S. decolorationis have been reported. However, no complete S. decolorationis genome has been published yet, which limited exploring their metabolism and feasibility in application. Here, S. decolorationis Ni1-3 isolated from an electroplating wastewater treatment plant showed strong reduction capabilities on azo dyes and oxidized metals. In order to construct the complete genome, high-quality whole-genome sequencing of strain Ni1-3 were performed by using both Nanopore MinION and Illumina NovaSeq platforms, from which the first complete genome of S. decolorationis was obtained by hybrid assembly. The genome of strain Ni1-3 contains a megaplasmid and a circular chromosome which encodes more proteins than that of the strains LDS1 and S12 belonging to the same species. In addition, more Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) are identified in strain Ni1-3 genome. Importantly, 32 cytochrome-c and AzoR azoreductase coding genes are identified in the genome, which make strain Ni1-3 competent to degrade the azo dyes and versatile to bioremediate some other environmental pollution. The complete genome sequence of strain Ni1-3 can expand our knowledge toward its metabolic capabilities and potential, meanwhile, provide a reference to reassemble genomes of other S. decolorationis strains.


Assuntos
Shewanella , Compostos Azo , Biodegradação Ambiental , Oxirredução , Shewanella/genética
17.
Int J Mol Sci ; 22(17)2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34502553

RESUMO

Herein, we report on the reaction of nitro-substituted azidobenzofuroxans with 1,3-dicarbonyl compounds in basic media. The known reactions of benzofuroxans and azidofuroxans with 1,3-dicarbonyl compounds in the presence of bases are the 1,3-dipolar cycloaddition and the Beirut reaction. In contrast with this, azidonitrobenzofuroxan reacts with 1,3-carbonyl compounds through Regitz diazo transfer, which is the first example of this type of reaction for furoxan derivatives. This difference is seemingly due to the strong electron-withdrawing effect of the superelectrophilic azidonitrobenzofuroxan, which serves as the azido transfer agent rather than 1,3-dipole in this case.


Assuntos
Compostos Azo/química , Benzoxazóis/química , Química Farmacêutica/métodos , Reação de Cicloadição , Animais , Humanos , Espectroscopia de Ressonância Magnética/métodos , Espectrometria de Massas/métodos , Modelos Químicos , Estrutura Molecular , Estereoisomerismo
18.
ACS Chem Neurosci ; 12(18): 3347-3357, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34469111

RESUMO

Azobenzene-based quaternary ammonium compounds provide optical control of ion channels and are considered promising agents for regulation of neuronal excitability and for restoration of the photosensitivity of retinal cells. However, the selectivity of the action of these compounds remains insufficiently known. We studied the action of DENAQ (diethylamine-azobenzene-quaternary ammonium) and DMNAQ (dimethylamine-azobenzene-quaternary ammonium) on ionotropic glutamate receptors in rat brain neurons. In the dark, both compounds applied extracellularly caused fast and reversible inhibition of NMDA (N-methyl-d-aspartate) receptor-mediated currents with IC50 values of 10 and 5 µM, respectively. Light-induced transformation of DENAQ and DMNAQ to their cis forms caused the IC50 values to increase to 30 and 27 µM, respectively. Detailed analysis of this action revealed a complex nature consisting of fast inhibitory and slower potentiating effects. The AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptors were only weakly affected independently on illumination. We conclude that, in addition to their long-lasting intracellular action, which persists after washout, azobenzene-based quaternary ammonium compounds should affect glutamatergic transmission and synaptic plasticity during treatment. Our findings also extend the list of soluble photoswitchable inhibitors of NMDA receptors. While the site(s) and mechanisms of action are unclear, the effect of DENAQ demonstrates strong pH dependence. At acidic pH values, DENAQ potentiates both NMDA and AMPA receptors.


Assuntos
Compostos de Amônio Quaternário , Receptores de N-Metil-D-Aspartato , Animais , Compostos Azo , Compostos de Amônio Quaternário/farmacologia , Ratos , Receptores de AMPA , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico
19.
J Hazard Mater ; 416: 126237, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492989

RESUMO

A simple method is reported for the preparation of silver nanoparticle (AgNP) embedded pH-responsive hydrogel microparticle catalyst via Michael addition gelation and in-situ silver nitrate (AgNO3) reduction. The AgNP-hydrogel microsphere exhibited an efficient reduction of pollutants like 4-Nitrophenol (4-NP) and Congo red (CR) under acidic medium with turn over frequency (TOF) of ~170 h-1 and ~124 h-1 respectively. Interestingly, the activity of the catalysts was turned-OFF under a basic medium (≥ pH 12) due to the deswelling pH-responsive matrix surrounding the AgNPs. On the contrary, turning-OFF the hydrogenation of a cationic pollutant like methylene blue (MB) using high pH (≥ 12) was not possible, due to ionic interaction of MB molecules with the negatively charged catalyst at this pH. This feature was used to demonstrate selective hydrogenation of only MB from a mixture of 4-NP and MB. Finally, five recycling steps confirmed the reusability and practical application potential of the catalyst.


Assuntos
Compostos Azo , Nanopartículas Metálicas , Catálise , Hidrogéis , Microesferas , Nitrofenóis , Prata
20.
Environ Monit Assess ; 193(10): 638, 2021 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-34505189

RESUMO

Synthetic dyes used in the textile and paper industries pose a major threat to the environment. In the present research work, the adsorption efficiency of the natural adsorbent Strychnos potatorum Linn (Fam: Loganiaceae) seeds were examined against the reactive orange-M2R dye from aqueous solution by varying the process conditions such as contact time, pH, adsorbent dosage, and initial dye concentration on adsorption of anionic azo dye. This study compares different types of artificial neural networks which are feedforward artificial neural network (FANN) and nonlinear autoregressive exogenous (NARX) model to predict the efficiency of a cost-effective natural adsorbent Strychnos potatorum Linn seeds on removing reactive orange-M2R dye from aqueous solution. Twelve training algorithms of neural network were compared, and the prediction on the adsorption performance of anionic azo dye from aqueous solution using Strychnos potatonum Linn seeds was evaluated by using the root mean squared error (RMSE), mean absolute error (MAE), coefficient of determination (R2), and accuracy. For FANN model, Levenberg-Marquardt (LM) backpropagation with 19 hidden neurons was selected as the optimum FANN model, with R2 of 0.994 and accuracy of 87.20%, 98.21%, and 66.60% for training, testing, and validation datasets, respectively. For NARX model, LM with 8 hidden neurons was selected as the most suitable training algorithm, with R2 value of more than 0.99 and accuracy of 88.00%, 90.91%, and 75.00% for training, testing, and validation datasets, respectively. NARX model accurately predicted the adsorption of anionic azo dye from aqueous solution using Strychnos potatonum Linn seeds with better performance than FANN model.


Assuntos
Strychnos , Adsorção , Compostos Azo , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Cinética , Redes Neurais de Computação , Sementes
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