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1.
J Chromatogr A ; 1618: 460851, 2020 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-32008826

RESUMO

Mixed-mode cation-exchange stationary phases are useful for the separation of mixtures containing hydrophobic, acidic, and basic molecules. To ensure that weak organic bases are protonated and carboxylic acids are neutral low pH mobile phases are required. Mixed-mode stationary phases that are stable at pH < 3 are needed. We synthesized a crosslinked structure along the surface of thiol functionalized silica gel particles using the thiol-yne click reaction. The alkyne, 1,7-octadiyne, was added to the 3-mercaptopropyl silica gel, then crosslinked using 1,6-hexanedithiol. Elemental analysis showed low octadiyne ligand surface coverage, but, stoichiometrically, three sulfurs were added to each octadiyne ligand during the crosslinking step, indicating that crosslinking occurred. The effect of the crosslinking on the stability was tested with a 50:50 (v/v) pH 0.50 5% TFA aqueous:acetonitrile mobile phase at 70 °C for six days, over 35,000 column volumes. The stationary phase showed good stability with the retention of triphenylene decreasing only 20% during that time. The Tanaka test showed that the phase has a methylene selectivity of 1.20 ± 0.04, a high shape selectivity of 2.71 ± 0.03, and a 3.98 ± 0.05 cation-exchange factor at pH 2.70. The phase has a selectivity factor for nitrobenzene and benzene of 1.41 ± 0.01, indicating the electron donating charge transfer characteristic of the phase. The mixed-mode characteristics of the phase were investigated using a mixture of the monoamine neurotransmitters norepinephrine, dopamine, and serotonin. Baseline resolution of the monoamines could be obtained using a simple 20 mM potassium phosphate (pH 2.70)/methanol mobile phase. Altering both the methanol content and the potassium ion concentration altered the retention of the monoamines indicating mixed-mode cation exchange characteristic of the crosslinked stationary phase.


Assuntos
Química Click/métodos , Compostos de Sulfidrila/química , Acetonitrilos/química , Benzeno/química , Cátions , Cromatografia por Troca Iônica , Intervalos de Confiança , Elétrons , Elementos , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Neurotransmissores/análise , Nitrobenzenos/química , Ácido Trifluoracético/química , Água
2.
Chemosphere ; 247: 125832, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31931312

RESUMO

Anaerobic reduction of nitrobenzene (NB) can be efficiently enhanced bySupplementing withSulfide-modified nanoscale zerovalent iron (S-nZVI). In thisStudy,S/Fe ratio ofS-nZVI was further optimized for enhancing biological NB removal in anaerobicSystem amended withS-nZVI and inoculated by anaerobicSludge. The results indicated that the performance andStability of the coupled anaerobicSystem for NB reduction and aniline formation were remarkably improved byS-nZVI atS/Fe molar ratio of 0.3 (0.3S-nZVI). TheSecretion of extracellular polymericSubstances (EPS), transformation of volatile fatty acids (VFAs), yield of methane and activity ofSeveral key enzymes could be efficiently improved by 0.3S-nZVI. Furthermore,Species related to NB reduction, fermentation, electroactivity and methanogenesis could be enriched in 0.3S-nZVI coupled anaerobicSystem, with remarkable improvement in the biodiversity observed. ThisStudy demonstrated thatSulfidation would be a promising method to improve the performance of nZVI in coupled anaerobicSystems for the removal of recalcitrant nitroaromatic compounds from wastewater.


Assuntos
Ferro/análise , Nitrobenzenos/isolamento & purificação , Sulfetos/análise , Poluentes Químicos da Água/metabolismo , Anaerobiose , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Ferro/farmacologia , Metano/biossíntese , Metano/metabolismo , Nitrobenzenos/metabolismo , Sulfetos/farmacologia , Águas Residuárias/química , Poluentes Químicos da Água/análise
3.
Chemosphere ; 248: 125978, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31995734

RESUMO

The searching for efficient and economical redox mediators to promote the treatment of wastewater containing recalcitrant organic compounds is greatly needed. In this study, the redox mediator activities of four different lignite samples to facilitate the bioreduction of nitrobenzene by Shewanella oneidensis MR-1 were tested for the first time. The initial nitrobenzene reduction rate was increased by 40.4%-90.3% in the presence of 50 mg/L of different lignite samples. Lignite collected from Xinjiang (XJL) having more oxygenated groups performed better in enhancing nitrobenzene bioreduction. The stimulating effects increased with the increase of lignite dosage (0-200 mg/L) and the decrease of lignite particle size (150-0.1 µm). However, the pristine XJL samples with assorted sizes of particles exhibited better stimulating effects than size-fractionated ones, implying that different-sized XJL particles might have synergetic effects on the bioreduction process. When humic acid or iron was removed from XJL, its promoting effects were decreased, demonstrating the crucial roles of both components in lignite-enhanced nitrobenzene bioreduction. Nitric acid treatment could form more oxygenated moieties on lignite surface, which played vital roles in promoting nitrobenzene bioreduction. The initial nitrobenzene bioreduction rate in the presence of HNO3-treated XJL was 80.8% higher than that obtained with pristine XJL. This study proposed an effective and readily available redox mediator that could be applied to promote the bioreduction of recalcitrant electrophilic pollutants.


Assuntos
Biodegradação Ambiental , Carvão Mineral , Poluentes Ambientais/metabolismo , Nitrobenzenos/metabolismo , Elétrons , Substâncias Húmicas , Ferro , Nitrobenzenos/análise , Compostos Orgânicos , Oxirredução , Shewanella , Águas Residuárias
4.
PLoS One ; 15(1): e0217665, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923248

RESUMO

Olfactory sense remains elusive regarding the primary reception mechanism. Some studies suggest that olfaction is a spectral sense, the olfactory event is triggered by electron transfer (ET) across the odorants at the active sites of odorant receptors (ORs). Herein we present a Donor-Bridge-Acceptor model, proposing that the ET process can be viewed as an electron hopping from the donor molecule to the odorant molecule (Bridge), then hopping off to the acceptor molecule, making the electronic state of the odorant molecule change along with vibrations (vibronic transition). The odorant specific parameter, Huang-Rhys factor can be derived from ab initio calculations, which make the simulation of ET spectra achievable. In this study, we revealed that the emission spectra (after Gaussian convolution) can be acted as odor characteristic spectra. Using the emission spectrum of ET, we were able to reasonably interpret the similar bitter-almond odors among hydrogen cyanide, benzaldehyde and nitrobenzene. In terms of isotope effects, we succeeded in explaining why subjects can easily distinguish cyclopentadecanone from its fully deuterated analogue cyclopentadecanone-d28 but not distinguishing acetophenone from acetophenone-d8.


Assuntos
Percepção Olfatória/genética , Neurônios Receptores Olfatórios/metabolismo , Receptores Odorantes/genética , Olfato/genética , Benzaldeídos/farmacologia , Respiração Celular/genética , Transporte de Elétrons/genética , Humanos , Cianeto de Hidrogênio/farmacologia , Isótopos/farmacologia , Nitrobenzenos/farmacologia , Odorantes/análise , Percepção Olfatória/fisiologia , Neurônios Receptores Olfatórios/química , Receptores Odorantes/metabolismo , Olfato/fisiologia , Vibração
5.
Environ Pollut ; 256: 113405, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31672347

RESUMO

To improve catalytic performance and stability of Ag nanoparticles (Ag NPs), a facile ultrasonication-assisted chemical reduction method was developed to fabricate reduced graphene oxide (rGO) aerogels loaded with 1-3 nm Ag NPs under the normal temperature and pressure. The ultrasonication facilitated the dispersion of Ag(I) in the form of silver ammonia and anchored onto GO nanosheets. Ag(I) and GO were simultaneously reduced to Ag(0) immobilizing onto 3D rGO hydrogels within the heterogeneous liquid phase, and ultimately formed 3D rGO-Ag NPs aerogels. The 3D rGO-Ag NPs aerogels displayed superb catalytic performance for the reduction of nitrobenzene (NB), 1,3-dinitrobenzene (DNB) and 4-nitrophenol (NP) into aniline, 1,3-diaminobenzene and 4-aminophenol, respectively. The individual reduction rate Kobs for NB, DNB and NP were 0.168 h-1, 0.109 h-1 and 0.092 h-1, which were much higher than those of other Ag NPs-based materials. Moreover, the immobilization of 1-3 nm Ag NPs in 3D rGO-Ag NPs was stable during the whole reduction reaction without aggregation and leaching. The high stability of Ag NPs in 3D rGO-Ag NPs and superb performance on catalytic reduction of nitroaromatic compounds (NACs) could be concluded into ultrasonication influence in the preparation procedure and synergistic effect of Ag NPs and 3D rGO in the catalytic reduction process. The simple ultrasonication-assisted chemical reduction approach provided a scaled-up application prospect in catalytic reduction of NACs by metal nanoparticle catalysts.


Assuntos
Grafite/química , Prata/química , Aminofenóis , Proteínas de Transporte , Catálise , Dipeptídeos , Nanopartículas Metálicas/química , Proteínas de Neoplasias , Nitrobenzenos , Nitrofenóis
6.
Environ Geochem Health ; 42(1): 109-120, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31037581

RESUMO

Nowadays, nanocarbon is widely employed to enwrap into fertilizers. However, the influence of nanocarbon on the transportation of contaminants from soil to plants and its mechanism remain unclear. In this study, pentachloronitrobenzene (PCNB), a typical organochlorine fungicide utilized all over the world, was chosen as the target contaminant to investigate the influence of nanocarbon on its transportation in soil-pak choi system. The maximum PCNB concentration in the root and leaf reached to 112 and 86 ng/g, respectively, demonstrating that PCNB would be absorbed by pak choi. The ratio of PCNB between leaf and root indicated that nanocarbon promoted root of pak choi to absorb PCNB. The transportation of PCNB inside plant was inhibited when pak choi was planted in soil containing higher concentration of nanocarbon. Human risk assessment showed that people consuming the pak choi in this study would not experience risk. However, in vitro toxicity test indicated that PCNB could directly impair intestinal epithelial cells (Caco-2 cells) and thus pose a potential risk to human intestine.


Assuntos
Brassica/metabolismo , Fertilizantes , Nitrobenzenos/farmacocinética , Nitrobenzenos/toxicidade , Poluentes do Solo/farmacocinética , Transporte Biológico , Brassica/química , Células CACO-2 , Exposição Dietética , Contaminação de Alimentos , Fungicidas Industriais/farmacocinética , Fungicidas Industriais/toxicidade , Humanos , Nanoestruturas , Folhas de Planta/química , Folhas de Planta/metabolismo , Raízes de Plantas/química , Raízes de Plantas/metabolismo , Medição de Risco , Solo/química , Poluentes do Solo/toxicidade , Testes de Toxicidade Aguda
7.
Chemosphere ; 238: 124636, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31470308

RESUMO

Electrochemical reduction process is a promising method for wastewater treatment, and its performance is determined by cathode material. Nitrogen doped carbon is a kind of favorable cathode material for electrochemical reduction, but deep understanding for the effect of nitrogen concentration and reduction pathway is still needed. In this paper, nitrogen doped porous carbon (NPC) with different nitrogen concentration were fabricated by directly carbonization of ZIF-8 under various temperatures. The electrochemical reduction performance of NPCs was evaluated by reducing nitrobenzene (NB), and the effects of nitrogen concentration were discussed. NPC with 22.7% nitrogen concentration exhibited the best NB reduction performance with the NB removal constant about 1.0 h-1 under optimal conditions; the NB removal rate and aniline (AN) production on this NPC are 4.2 and 8.5 times higher than graphite electrode. Further H* quenching experiment indicates the NPC electrochemical reduction process mainly following an indirect hydrogenation reduction pathway. These results offer some insights into the electrochemical reduction process on nitrogen doped carbon, which may facilitate the design of efficient metal free carbon based catalyst for wastewater electrochemical pretreatment.


Assuntos
Carbono , Técnicas Eletroquímicas/métodos , Nitrobenzenos/química , Nitrogênio , Substâncias Redutoras/química , Compostos de Anilina/síntese química , Catálise , Eletrodos , Porosidade , Águas Residuárias/química , Purificação da Água/métodos
8.
Chemosphere ; 239: 124806, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726521

RESUMO

Nitrobenzene (NB) is recalcitrant to microbial biodegradation due to the electron-deficient character of the nitro group (NO2-). Prior work has found that the reductant could enhance NB biodegradation by providing excess electron donors. However, the existing theory couldn't explain the increase-and-decrease pattern of the NB biodegradation rate with an increase in a reductant concentration. Our results suggest that the reductant affects NB biodegradation by two mechanisms: the available electron donors and the stimulation or inhibition of biomass growth, which are linked by a pseudo-first-order reaction kinetics. In addition, the results showed that directly inoculating the plain soil into the aquatic system and then allowing the synergistic effect of the organic reductant (ascorbic acid) and the substrate (peptone) enhance NB biodegradation. Employing the new method, 200 mg L-1 NB was transformed in 72 h. GC-MS analysis detected two novel intermediate metabolites, indicating that NB was degraded into aniline and further transformed into acetanilide and 9-octadecenamide before its mineralization. This study sheds light on how to exploit the synergistic effects of the availability of excess electron donors and biomass growth by controlling the reductant and a substrate in the right concentration range (e.g., ascorbic acid < 0.8 mgL-1 + peptone).


Assuntos
Ácido Ascórbico/química , Biodegradação Ambiental , Nitrobenzenos/metabolismo , Peptonas/química , Poluentes do Solo/análise , Solo/química , Acetanilidas/síntese química , Compostos de Anilina/síntese química , Estudos de Viabilidade , Cinética , Ácidos Oleicos/síntese química
9.
Chemosphere ; 239: 124686, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31494321

RESUMO

Oxidative degradation of aniline in aqueous solution was performed by the sono-activated peroxydisulfate coupled with PbO process, wherein a dramatic synergistic effect was found. Experiments were carried out in the batch-wise mode to investigate the influence of various operation parameters on the sonocatalytic behavior, such as ultrasonic power intensity, peroxydisulfate anion concentrations and PbO dosages. According to the scavenging effect of ethanol, methanol and tert-butyl alcohol, the principal oxidizing agents were presumed to be sulfate radicals descended from peroxydisulfate anions, activated via ultrasound or sonocatalysis of PbO. Based on the results attained from gas chromatograph-mass spectrometer, it was hypothesized that aniline was initially oxidized into iminobenzene radicals, followed with formation of nitrosobenzene, p-benzoquinonimine and nitrobenzene respectively. Condensation of nitrosobenzene with aniline generated azobenzene. Phenol was detected as one of degradation intermediates, which was sequentially converted into hydroquinone and p-benzoquinone.


Assuntos
Compostos de Anilina/química , Chumbo/química , Óxidos/química , Fenol/química , Sulfatos/química , Compostos Azo/síntese química , Benzoquinonas/síntese química , Etanol/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Hidroquinonas/síntese química , Metanol/metabolismo , Nitrobenzenos/síntese química , Compostos Nitrosos/síntese química , Oxidantes , Oxirredução , Semicondutores , Ondas Ultrassônicas , terc-Butil Álcool/metabolismo
10.
Inorg Chem ; 58(24): 16326-16329, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31793291

RESUMO

A new strategy for a G-quadruplex fluorescent probe based on a nitro-substituted ruthenium complex is described. G-quadruplex DNA can be distinguished from double- or single-strand DNA by the naked eye. This ability originates from variation of the degree of protection of the nitro group on the complex from water by G-quadruplex and other structure DNAs.


Assuntos
Complexos de Coordenação/química , DNA/análise , Corantes Fluorescentes/química , Quadruplex G , Nitrobenzenos/química , Colorimetria/métodos , DNA/genética , Humanos , Rutênio/química
11.
Genes (Basel) ; 11(1)2019 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-31878175

RESUMO

Glutathione S-transferases (GSTs)-an especially plant-specific tau class of GSTs-are key enzymes involved in biotic and abiotic stress responses. To improve the stress resistance of crops via the genetic modification of GSTs, we predicted the amino acids present in the GSH binding site (G-site) and hydrophobic substrate-binding site (H-site) of OsGSTU17, a tau class GST in rice. We then examined the enzyme activity, substrate specificity, enzyme kinetics and thermodynamic stability of the mutant enzymes. Our results showed that the hydrogen bonds between Lys42, Val56, Glu68, and Ser69 of the G-site and glutathione were essential for enzyme activity and thermal stability. The hydrophobic side chains of amino acids of the H-site contributed to enzyme activity toward 4-nitrobenzyl chloride but had an inhibitory effect on enzyme activity toward 1-chloro-2,4-dinitrobenzene and cumene hydroperoxide. Different amino acids of the H-site had different effects on enzyme activity toward a different substrate, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole. Moreover, Leu112 and Phe162 were found to inhibit the catalytic efficiency of OsGSTU17 to 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, while Pro16, Leu112, and Trp165 contributed to structural stability. The results of this research enhance the understanding of the relationship between the structure and function of tau class GSTs to improve the abiotic stress resistance of crops.


Assuntos
Glutationa Transferase/química , Glutationa Transferase/metabolismo , Nitrobenzenos/metabolismo , Oryza/enzimologia , Derivados de Benzeno/farmacologia , Sítios de Ligação , Dinitroclorobenzeno/farmacologia , Estabilidade Enzimática , Glutationa Transferase/efeitos dos fármacos , Ligação de Hidrogênio , Oryza/química , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Ligação Proteica , Especificidade por Substrato , Termodinâmica
12.
ACS Appl Mater Interfaces ; 11(47): 44545-44555, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31675208

RESUMO

N-doped graphene (NG), S-doped graphene (SG), and N and S co-doped graphene nanocatalysts with different doping sequences (N-SG and S-NG) are successfully synthesized by a facile low-temperature hydrothermal method. By changing the synthetic sequence, S-NG significantly increases the electron transport rate of the sensor and the electrocatalytic ability compared to NG, SG, and N-SG due to the optimal proportion of doping element content and suitable N- and S-bonding configurations. The origin of the synergistic effect of N and S co-doped graphene is confirmed. Traces of S doping greatly enhance the electrochemical performance. The large volume of S-Ox groups may prevent the analytes from approaching the catalytic sites of the sensing materials due to a steric hindrance effect. S-NG, which possesses less S-Ox groups, exhibits better performance than N-SG. Pyridinic N plays an important role in enhancing the electrochemical activity and conductivity. The simultaneous determination of aniline (AN), p-phenylenediamine (PPD), and nitrobenzene (NB) as typical toxic pollutants is performed by employing the S-NG nanoarchitecture. The detection limits (S/N = 3) for AN, PPD, and NB are 0.023, 0.051, and 0.216 µM, respectively. In addition, the S-NG sensors also have excellent anti-interference, stability, and reproducibility. The precise control and synthesis of multiheteroatoms into graphene represent a promising strategy to enhance the electrocatalytic performance in energy and environmental fields.


Assuntos
Compostos de Anilina/análise , Técnicas Eletroquímicas/métodos , Poluentes Ambientais/análise , Grafite/química , Nitrobenzenos/análise , Nitrogênio/química , Fenilenodiaminas/análise , Enxofre/química , Catálise , Técnicas Eletroquímicas/instrumentação , Grafite/síntese química , Limite de Detecção
14.
Water Sci Technol ; 80(5): 902-910, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31746797

RESUMO

In this study, a mesoporous TiO2/carbon catalyst (TiO2/C) was prepared by a facile impregnation-carbonization approach to catalyze ozonation of p-chloronitrobenzene (p-CNB). The catalyst was well characterized and the catalytic efficiency under various conditions was systematically evaluated. TiO2/C has a disordered mesostructure with a high specific surface area. 92.8% of p-CNB (2 µmol/L) can be degraded within 20 min in the TiO2/C/O3 system in the presence of 1 mg/L O3, 100 mg/L catalyst, at pH = 5. Based on the evaluation of the effect of basic parameters, it could be deduced that the removal of p-CNB relied on the synthetic effect of catalysis by TiO2/C and the autocatalytic induction of p-CNB. The removal efficiency of p-CNB, the structure change and the leaching of Ti ions were also evaluated in five cycles, indicating TiO2/C is stable and recyclable for catalytic ozonation in water treatment.


Assuntos
Ozônio , Poluentes Químicos da Água , Purificação da Água , Carbono , Catálise , Nitrobenzenos , Oxirredução
15.
Chemotherapy ; 64(3): 138-145, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31639786

RESUMO

BACKGROUND: PD-L1 is a membrane protein with inhibitory effects on immune responses, whose expression has been correlated with high aggressiveness and the propensity of melanoma to metastasize. The nitrobenzoxadiazole (NBD) NBDHEX and its analog MC3181 are endowed with strong antitumor activity towards melanoma and a significant ability to reduce its adhesion and invasiveness. Therefore, we investigated whether PD-L1 status could affect cell sensitivity to the cytotoxic effects of NBDs. We then evaluated the effects of NBDHEX on PD-L1 expression and autophagy in melanoma cells. We used the BRAF-mutated A375 melanoma cell line and an A375 variant population enriched for PD-L1+ cells as a model. The cytotoxic effects of NBDs were evaluated in comparison to those of the BRAF inhibitor vemurafenib and the autophagy inhibitor chloroquine. METHODS: The effect of NBDHEX on autophagy was determined by measuring LC3-II and p62 protein levels by Western blot. The cytotoxic activity of the compounds was evaluated by sulforhodamine B assay. PD-L1 expression and plasma membrane localization were analyzed by FACS and Western blot analysis. RESULTS: NBDHEX behaves as a late-autophagy inhibitor in A375 melanoma cells, as previously found in other tumor cell lines. NBDHEX and MC3181 showed strong and comparable cytotoxic activity in both parental and PD-L1+ A375 cells, with IC50 values in the sub-micromolar range. Conversely, cells sorted for high PD-L1 expression had lower sensitivity to both the BRAF inhibitor vemurafenib and the autophagy inhibitor chloroquine. NBDHEX treatment did not change the total expression and cell surface localization of PD-L1 in both parental and PD-L1+ A375 cells. CONCLUSIONS: Our data suggest that NBDs may represent a promising treatment strategy for melanoma with elevated PD-L1 expression.


Assuntos
Autofagia/efeitos dos fármacos , Antígeno B7-H1/metabolismo , Glutationa Transferase/antagonistas & inibidores , Nitrobenzenos/farmacologia , Oxidiazóis/farmacologia , Antígeno B7-H1/genética , Linhagem Celular Tumoral , Cloroquina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Glutationa Transferase/metabolismo , Humanos , Melanoma , Nitrobenzenos/química , Oxidiazóis/química , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas B-raf/metabolismo , Vemurafenib/farmacologia
16.
Enzyme Microb Technol ; 131: 109434, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31615682

RESUMO

Widely used in multiple industrial processes, nitro-aromatic compounds, especially nitrobenzene, in low temperature environment are considered as heavy pollutants. Among the disposal methods, the bioreduction method has attracted much attention. In this study, a novel cold-adapted nitroreductase gene (psntr) was cloned from Antarctic sea-ice bacteria Psychrobacter sp. ANT206. The psntr gene was 813 bp in length and encoded a protein with flavin mononucleotide (FMN) binding sites. Homology modeling was performed to obtain structural information such as the longer loops and reduced amount of hydrogen bonds, which might be related to the high catalytic efficiency of PsNTR at low temperature. The psntr gene was successfully cloned in cold-shock pCold I vector and transformed to the expression host Escherichia coli (E. coli) BL21 with the induction by isopropyl ß-D-thiogalactoside (IPTG) at low temperature (16 °C) for 24 h. The recombinant PsNTR (rPsNTR) was purified using Ni-NTA with the specific activity of 51.59 µmol/min/mg. Interestingly, rPsNTR displayed the highest activity at 25 °C and still maintained 46.9% of the activity at 0 °C. rPsNTR also exhibited the highest activity (136.4%) at 1.0 M NaCl with incredible salt tolerance. The kinetic parameters and substrates specificity analysis demonstrated that rPsNTR could reduce various nitro-aromatic compounds. Moreover, the result of the reduction capability revealed that the recombinant E. coli exhibited a maximum nitrobenzene reduction rate of 3.03 mM/h at 16 °C. These findings revealed that the characteristics of rPsNTR might make it an excellent candidate for the bioreduction of various nitro-aromatic compounds in the low temperature and high-salt wastewater.


Assuntos
Temperatura Baixa , Nitrobenzenos/metabolismo , Nitrorredutases/isolamento & purificação , Nitrorredutases/metabolismo , Psychrobacter/enzimologia , Biotransformação , Clonagem Molecular , Biologia Computacional , Poluentes Ambientais/metabolismo , Estabilidade Enzimática , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Cinética , Nitrorredutases/química , Nitrorredutases/genética , Oxirredução , Conformação Proteica , Psychrobacter/genética , Cloreto de Sódio/metabolismo
17.
Chem Commun (Camb) ; 55(82): 12288-12291, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31524898

RESUMO

Here we present a set of fluorescent cages prepared by tethering fluorescent dyes to a photolabile group. The developed molecules enable caging of signalling lipids, their delivery to specific cellular membranes, with further imaging, quantification, and controlled photorelease of active lipids in living cells.


Assuntos
Corantes Fluorescentes/química , Metabolismo dos Lipídeos , Lipídeos/química , Nitrobenzenos/química , Transdução de Sinais , Membrana Celular/química , Células HeLa , Humanos
18.
Chemosphere ; 237: 124546, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549658

RESUMO

The Fe-modified spherical meso-silica MCM-41 was synthesized via the base precipitation with Fe3+/urea, and the structure was characterized. Especially, the selective and enhanced adsorption characters and mechanism of the monosubstituted benzenes were investigated. The results showed that Fe modification increased the specific surface area of MCM-41 and retained the mesopore structure. Importantly, adsorption of the monosubstituted benzenes indicated that the adsorption behavior of the monosubstituted benzenes on the Fe-modified MCM-41 (Fe-MCM-41) was a monolayer adsorption on the heterogeneous surfaces, and it showed great selective adsorption towards aniline, and the maximum adsorption capacity of the Fe-MCM-41 towards aniline was 17.5 and 7.9 times of nitrobenzene and phenol. Additionally, the adsorption process and the isotherm of aniline conformed to the pseudo-second order kinetic mode and the Langmuir mode. The maximum adsorption capacity of the Fe-MCM-41 and the pure MCM-41 towards aniline were 17.9 and 1.9 mg g-1, which indicated that the Fe modification significantly enhanced the adsorption capacity of MCM-41 towards aniline. Mechanism analysis reveals that the selective adsorption of the monosubstituted benzenes was attributed to the electron donating/withdrawing capacity of the substituent groups on benzene ring. Due to the electron withdrawing capacity of O atom, the exposed Fe atom of the ferric oxide loaded in the Fe-MCM-41 gave a strong electrophilic surface, which electrostatically interacted with the electron donating group (amino) in aniline.


Assuntos
Derivados de Benzeno/química , Compostos Férricos/química , Dióxido de Silício/química , Adsorção , Compostos de Anilina/química , Benzeno/química , Nitrobenzenos/química , Fenol/química , Poluentes Químicos da Água/química
19.
Biomed Pharmacother ; 119: 109398, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31493747

RESUMO

[1-(4-chloro-3-nitrobenzenesulfonyl)-1H-indol-3-yl]-methanol (CIM) has been used as a bioactive agent for inhibiting tumor growth and angiogenesis via mitogen-activated protein kinase (MAPK) and NF-κB blocking. The present work was undertaken to investigate the potential of CIM against psoriasis using imiquimod (IMQ)-stimulated psoriasis-like mouse and in vitro HaCaT keratinocytes as the models. We demonstrated that topical CIM treatment reduced IMQ-activated scaling, erythema, and barrier dysfunction. This compound also restrained the recruitment of neutrophils. The cytokines, including TNF-α, IL-1ß, IL-6, and IL-17 in psoriasiform skin, can be attenuated to normal baseline by CIM. Topically applied CIM can be easily delivered into skin based on the affinity with stratum corneum (SC) ceramides. IMQ intervention increased the permeability by 3-fold as compared to healthy skin. CIM ameliorated psoriatic lesion without incurring overt signs of irritation. Both TNF-α and IMQ were employed as the stimulators to activate HaCaT for reciprocal elucidation of the mechanism of action. CIM inhibited the overexpression of IL-1ß, IL-6, and IL-24 in HaCaT. CIM exerted anti-inflammatory activity by suppressing the phosphorylation of NF-κB and activator protein-1 (AP-1) through MAPK pathways. Our results indicate that CIM has potential as the antipsoriatic molecule. The detailed signaling pathways still need further investigation.


Assuntos
Sistemas de Liberação de Medicamentos , Indóis/administração & dosagem , Indóis/uso terapêutico , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Nitrobenzenos/administração & dosagem , Nitrobenzenos/uso terapêutico , Psoríase/tratamento farmacológico , Psoríase/metabolismo , Fator de Transcrição AP-1/metabolismo , Administração Cutânea , Animais , Linhagem Celular , Humanos , Imiquimode , Indóis/química , Indóis/farmacologia , Masculino , Camundongos Endogâmicos BALB C , Camundongos Nus , Nitrobenzenos/química , Nitrobenzenos/farmacologia , Fosforilação , Fator de Necrose Tumoral alfa/metabolismo
20.
Environ Sci Pollut Res Int ; 26(31): 32165-32174, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31494854

RESUMO

To achieve superior advanced oxidation processes (AOPs), transitional state activators are of great significance for the production of active radicals by H2O2, while instability limits their activation efficiency. In this study, density functional theory calculation (DFT) results showed that Cu+ exhibits excellent H2O2 activation performance, with Gibbs free energy change (ΔG) of 33.66 kcal/mol, two times less than that of Cu2+ (77.83 kcal/mol). Meanwhile, an electro-Fenton system using Cu plate as an anode was proposed for in situ generation of Cu+. The released Cu with low-valence state can be well-confined on the surface of the exciting electrode, which was confirmed by X-ray photoelectron spectroscopy (XPS), Raman, and UV-vis spectroscopy. The hydroxyl radicals in this Cu-based electro-Fenton system were determined by the electron spin resonance (ESR). The nitrobenzene degradation ratio was greatly increased by 43.90% with the introduction of the proposed in situ electrochemical Cu+ generation process. Various characterization results indicated that the production of Cu+ was the key factor in the highly efficient Cu-based electro-Fenton reaction.


Assuntos
Cobre/análise , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Nitrobenzenos/química , Cobre/química , Eletrodos , Oxirredução
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