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1.
Chem Asian J ; 15(3): 327-337, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31957936

RESUMO

Microbial secondary metabolites (SMs) have long been viewed as a significant source of novel pharmaceutical and agrochemical molecules. With the increasing availability of genomic data, numerous biosynthetic gene clusters (BGCs) have been discovered. Despite the presence of tens of thousands of BGCs that can theoretically produce extremely diverse SMs, many gene clusters remain in a silent state under axenic culture conditions. Co-culture is a promising research approach as it stimulates the expression of cryptic BGCs to produce novel metabolites and also mimics natural interspecies interactions in a laboratory environment. In recent years, the roles of SMs in microbial communication have caught the attention of researchers and our understanding of microbes and their production of remarkable SMs has improved. SMs may be extensively involved in a variety of communication events among microorganisms. We herein summarize certain representative findings in the field of chemical communication involving SMs in co-culture systems.


Assuntos
Bactérias/química , Metabolismo Secundário , Aspergillus fumigatus/química , Aspergillus fumigatus/metabolismo , Aspergillus fumigatus/virologia , Bactérias/metabolismo , Bactérias/virologia , Montagem e Desmontagem da Cromatina , Óxido Nítrico/química , Óxido Nítrico/metabolismo , Streptomyces/química , Streptomyces/metabolismo , Streptomyces/virologia , Vírus/patogenicidade
2.
Biochemistry (Mosc) ; 84(11): 1390-1402, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31760925

RESUMO

Terminal oxidases of aerobic respiratory chains catalyze the transfer of electrons from the respiratory substrate, cytochrome c or quinol, to O2 with the formation of two H2O molecules. There are two known families of these membrane oxidoreductases: heme-copper oxidase superfamily and bd-type oxidase family (cytochromes bd) found in prokaryotes only. The redox reaction catalyzed by these enzymes is coupled to the generation of proton motive force used by the cell to synthesize ATP and to perform other useful work. Due to the presence of the proton pump, heme-copper oxidases create the membrane potential with a greater energy efficiency than cytochromes bd. The latter, however, play an important physiological role that enables bacteria, including pathogenic ones, to survive and reproduce under adverse environmental conditions. This review discusses the features of organization and molecular mechanisms of functioning of terminal oxidases from these two families in the light of recent experimental data.


Assuntos
Cobre/química , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Heme/química , Biocatálise , Transporte de Elétrons , Complexo de Proteínas da Cadeia de Transporte de Elétrons/química , Escherichia coli/metabolismo , Geobacillus/metabolismo , Óxido Nítrico/química , Óxido Nítrico/metabolismo , Oxirredução
3.
Chem Commun (Camb) ; 55(98): 14789-14792, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31761922

RESUMO

We have reported rational design of a polymeric NO delivery micelle as a cytosol-selective NO bomb. Protected NO-donors are released from the micelle under endolysosomal conditions, and then deprotected by cytosolic glutathione. Cytosol-selective NO delivery facilitates significant tumor regression without the aid of other therapeutic modalities even in intravenous administrations.


Assuntos
Antineoplásicos/química , Citosol/metabolismo , Micelas , Óxido Nítrico/química , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/química , Glutationa/metabolismo , Humanos , Camundongos , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Óxido Nítrico/metabolismo , Óxido Nítrico/farmacologia , Óxido Nítrico/uso terapêutico , Polímeros/química , Transplante Heterólogo
4.
Pharm Nanotechnol ; 7(4): 279-303, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31595847

RESUMO

Nitric oxide (NO) is a short-lived, endogenously produced, signaling molecule which plays multiple roles in mammalian physiology. Underproduction of NO is associated with several pathological processes; hence a broad range of NO donors have emerged as potential therapeutics for cardiovascular and respiratory disorders, wound healing, the immune response to infection, and cancer. However, short half-lives, chemical reactivity, rapid systemic clearance, and cytotoxicity have hindered the clinical development of most low molecular weight NO donors. Hence, for controlled NO delivery, there has been extensive effort to design novel NO-releasing biomaterials for tumor targeting. This review covers the effects of NO in cancer biology, NO releasing moieties which can be used for NO delivery, and current advances in the design of NO releasing biomaterials focusing on their applications for tumor therapy.


Assuntos
Antineoplásicos/farmacologia , Portadores de Fármacos , Neoplasias/tratamento farmacológico , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/farmacologia , Antineoplásicos/química , Antineoplásicos/uso terapêutico , Sistemas de Liberação de Medicamentos , Humanos , Óxido Nítrico/química , Óxido Nítrico/uso terapêutico , Doadores de Óxido Nítrico/química , Doadores de Óxido Nítrico/uso terapêutico
5.
Molecules ; 24(20)2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31600965

RESUMO

The electronic, structural and optical properties (including Spin-Orbit Coupling) of metal nitrosyl complexes [M(CN)5(NO)]2- (M = Fe, Ru or Os) are investigated by means of Density Functional Theory, TD-DFT and MS-CASPT2 based on an RASSCF wavefunction. The energy profiles connecting the N-bound (η1-N), O-bound (η1-O) and side-on (η2-NO) conformations have been computed at DFT level for the closed shell singlet electronic state. For each structure, the lowest singlet and triplet states have been optimized in order to gain insight into the energy profiles describing the conformational isomerism in excited states. The energetics of the three complexes are similar-with the N-bound structure being the most stable-with one exception, namely the triplet ground state of the O-bound isomer for the iron complex. The conformation isomerism is highly unfavorable in the S0 electronic state with the occurrence of two energy barriers higher than 2 eV. The lowest bands of the spectra are assigned to MLCTNO/LLCTNO transitions, with an increasing MLCT character going from iron to osmium. Two low-lying triplet states, T1 (MLCTNO/LLCTNO) and T2 (MLCTNO/ILNO), seem to control the lowest energy profile of the excited-state conformational isomerism.


Assuntos
Fenômenos Químicos , Complexos de Coordenação/química , Estrutura Molecular , Óxido Nítrico/química , Conformação Molecular , Processos Fotoquímicos , Análise Espectral , Relação Estrutura-Atividade
6.
Chemosphere ; 235: 1146-1153, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561305

RESUMO

Waste is a misplaced resource. Herein, anionic (orange II sodium salt and Ponceau 2R) and cationic (Rhodamine B and Methylene blue) dye wastewater assisted photo-treatment (referred as DAPT) method was developed to modify sol-gel synthesized CeO2-TiO2 (CeTi) mixed oxide catalyst. Catalytic activity test results showed that both anionic and cationic dye wastewater could be used as "fuel" of photo-treatment to enhance the activity of CeTi catalyst in NO reduction and dichloromethane oxidation. Characterization and DFT calculation results revealed that DAPT process increased the amount of Ce3+ ions on CeTi samples, which could induce the formation of Ce-VO-Ti (oxygen vacancy (VO) in Ce-O-Ti short range structure). These Ce-VO-Ti defects not only could be adsorption sites for NH3, dichloromethane and oxygen, but also promoted the redox shift of Ce3++ Ti4+ ⇋ Ce4++ Ti3+ by enhancing the oxidizability of Ce4+ and Ti4+ species. Furthermore, defects changed the polarity of Ce-O and Ti-O, which was conducive to the activation of lattice oxygen. All these improvements contributed to the excellent catalytic activity of CeTi catalysts. We expected this work to be instructive on constructing structure-activity over CeO2-TiO2 based catalysts and utilizing dye wastewater.


Assuntos
Cério/química , Cloreto de Metileno/química , Óxido Nítrico/química , Titânio/química , Águas Residuárias/química , Adsorção , Catálise , Corantes , Oxirredução , Oxigênio/química
7.
Environ Sci Pollut Res Int ; 26(32): 33067-33075, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31512139

RESUMO

Fe/activated coke (AC) and Cr-Fe/AC catalysts with AC as a supporter and Cr and Fe as active components were prepared by an impregnation method for low-temperature selective catalytic reduction (SCR) of NO with NH3. The effects of Cr addition and its concentrations on the deNOx performance of Fe/AC catalysts were studied at low temperature. The Cr addition promotes the low-temperature SCR activity of the 8Fe/AC catalyst and the 8Fe6Cr/AC catalyst has the best low-temperature SCR deNOx performance, which the NOx conversions are greater than 90% at 160-240 °C. The 8Fe6Cr/AC catalyst has good water resistance. However, when 100 ppm SO2 was introduced into the reaction gas, its deNOx efficiency drops to 45% at 180 °C. To clarify the specific effects of Cr addition on the NOx conversions and sulfur poisoning, the Cr-Fe/AC catalysts were characterized by X-ray diffraction, BET, H2 temperature-programmed reduction, NH3 temperature-programmed desorption, X-ray photoelectron spectroscopy, and Fourier infrared spectroscopy. The addition of Cr into Fe/AC catalysts greatly increases the BET surface area and the number of weak and medium-strong acid sites on the catalyst surface and improves the ratio of Fe3+/Fe2+. These factors enhance the NOx conversion of 8Fe/AC catalyst. The formed sulfates and hydrogen sulfates cover the active sites on the catalyst surface, which lead to the sulfur poisoning of the 8Fe6Cr/AC catalyst. Graphical abstract.


Assuntos
Amônia/química , Modelos Químicos , Óxido Nítrico/química , Catálise , Coque , Temperatura Baixa , Oxirredução , Temperatura Ambiente , Água/química , Difração de Raios X
8.
Nihon Yakurigaku Zasshi ; 154(3): 115-120, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31527360

RESUMO

More than twenty years have passed since the demonstration of hydrogen sulfide (H2S) as a signaling molecule. Various roles of this molecule have been reported including neuromodulation, vascular relaxation, cytoprotection, anti-inflammation, and oxygen sensing. During the study of its effect on neuromodulation, we found TRP channels as a target of H2S, and later identified polysulfides (H2Sn) as chemical entity of the ligand. We found that H2S relaxes vasculatures in synergy with NO, and recently identified H2Sn as products produced by the chemical interaction between H2S and NO to exert the effect, suggesting that it may be a mechanism for the synergy between the two molecules. It has attracted attention that sulfite, a further metabolite of H2S and H2Sn, protects neurons from oxidative stress by a mechanism different from that by H2S and H2Sn.


Assuntos
Sulfeto de Hidrogênio/química , Transdução de Sinais , Sulfetos/química , Sulfitos/química , Humanos , Óxido Nítrico/química , Vasodilatadores/química
9.
ACS Appl Mater Interfaces ; 11(38): 34663-34675, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31490654

RESUMO

Apoptotic peptide (kla), which can trigger the mitochondria-mediated apoptotic programmed cell death, has been widely recognized as a potential anticancer agent. However, its therapeutic potential has been significantly impaired by its poor biostability, lack of tumor specificity, and particularly low cellular uptake. Herein, a linear peptide Arg-Trp-d-Arg-Asn-Arg (RWrNR) was identified as an integrin αvß3 specific ligand with a nanomolar dissociation constant (Kd = 0.95 nM), which can greatly improve kla antitumor activity (IC50 = 8.81 µM) by improving its cellular uptake, compared to the classic integrin-recognition motif c-RGDyK (IC50 = 37.96 µM). Particularly, the RWrNR-kla conjugate can be entrapped in acidic sensitive nanogels (RK/Parg/CMCS-NGs), composed of poly-l-arginine (Parg) and carboxymethyl chitosan (CMCS, pI = 6.8), which can not only carry out controlled release of RWrNR-kla in response to the tumor acidic microenvironment, and consequently enhance its tumor specificity and cell internalization, but also trigger tumor-associated macrophages to generate nitric oxide, leading to enhanced synergistic anticancer efficacy. Importantly, RK/Parg/CMCS-NGs have been proven to effectively activate the apoptosis signaling pathway in vivo and significantly inhibit tumor growth with minimal adverse effects. To summarize, RK/Parg/CMCS-NGs are a promising apoptotic peptide-based therapeutics with enhanced tumor accumulation, cytosolic delivery, and synergistic anticancer effects, thereby holding great potential for the treatment of malignant tumors.


Assuntos
Antineoplásicos , Apoptose/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Integrina alfaVbeta3/metabolismo , Neoplasias Experimentais , Óxido Nítrico , Peptídeos , Animais , Antineoplásicos/química , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteínas de Neoplasias , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Óxido Nítrico/química , Óxido Nítrico/farmacocinética , Óxido Nítrico/farmacologia , Peptídeos/química , Peptídeos/farmacocinética , Peptídeos/farmacologia , Células RAW 264.7 , Ensaios Antitumorais Modelo de Xenoenxerto
10.
ACS Appl Mater Interfaces ; 11(41): 37491-37501, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31532610

RESUMO

Microbial keratitis is a serious sight threatening infection affecting approximately two million individuals worldwide annually. While antibiotic eye drops remain the gold standard treatment for these infections, the significant problems associated with eye drop drug delivery and the alarming rise in antimicrobial resistance has meant that there is an urgent need to develop alternative treatments. In this work, a nitric oxide releasing contact lens gel displaying broad spectrum antimicrobial activity against two of the most common causative pathogens of microbial keratitis is described. The contact lens gel is composed of poly-ε-lysine (pεK) functionalized with nitric oxide (NO) releasing diazeniumdiolate moieties which enables the controlled and sustained release of bactericidal concentrations of NO at physiological pH over a period of 15 h. Diazeniumdiolate functionalization was confirmed by Fourier transform infrared (FTIR), and the concentration of NO released from the gels was determined by chemiluminescence. The bactericidal efficacy of the gels against Pseudomonas aeruginosa and Staphylococcus aureus was ascertained, and between 1 and 4 log reductions in bacterial populations were observed over 24 h. Additional cell cytotoxicity studies with human corneal epithelial cells (hCE-T) also demonstrated that the contact lens gels were not cytotoxic, suggesting that the developed technology could be a viable alternative treatment for microbial  keratitis.


Assuntos
Anti-Infecciosos , Lentes de Contato , Ceratite/tratamento farmacológico , Óxido Nítrico , Infecções por Pseudomonas/tratamento farmacológico , Pseudomonas aeruginosa/crescimento & desenvolvimento , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/crescimento & desenvolvimento , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacologia , Epitélio Anterior/metabolismo , Epitélio Anterior/microbiologia , Epitélio Anterior/patologia , Humanos , Teste de Materiais , Óxido Nítrico/química , Óxido Nítrico/farmacologia
11.
Int J Mol Sci ; 20(15)2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31370152

RESUMO

Ocular infection due to microbial contamination is one of the main risks associated with the wearing of contact lens, which demands novel straightforward strategies to find reliable solutions. This contribution reports the preparation, characterization and biological evaluation of soft contact lenses (CL) releasing nitric oxide (NO), as an unconventional antibacterial agent, under daylight exposure. A tailored NO photodonor (NOPD) was embedded into commercial CL leading to doped CL with an excellent optical transparency (transmittance = 100%) at λ ≥ 450 nm. The NOPD results homogeneously distributed in the CL matrix where it fully preserves the photobehavior exhibited in solution. In particular, NO release from the CL and its diffusion in the supernatant physiological solution is observed upon visible light illumination. The presence of a blue fluorescent reporting functionality into the molecular skeleton of the NOPD, which activates concomitantly to the NO photorelease, allows the easy monitoring of the NO delivery in real-time and confirms that the doped CL work under daylight exposure. The NO photoreleasing CL are well-tolerated in both dark and light conditions by corneal cells while being able to induce good growth inhibition of Staphylococcus aureus under visible light irradiation. These results may pave the way to further engineering of the CL with NOPD as innovative ocular devices activatable by sunlight.


Assuntos
Antibacterianos/farmacologia , Lentes de Contato Hidrofílicas , Células Epiteliais/efeitos dos fármacos , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/química , Antibacterianos/efeitos da radiação , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/efeitos da radiação , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Córnea/citologia , Córnea/efeitos dos fármacos , Córnea/microbiologia , Córnea/efeitos da radiação , Células Epiteliais/citologia , Células Epiteliais/microbiologia , Células Epiteliais/efeitos da radiação , Corantes Fluorescentes/química , Humanos , Luz , Óxido Nítrico/química , Óxido Nítrico/efeitos da radiação , Doadores de Óxido Nítrico/química , Doadores de Óxido Nítrico/efeitos da radiação , Processos Fotoquímicos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/efeitos da radiação
12.
Biochim Biophys Acta Bioenerg ; 1860(9): 734-744, 2019 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-31376363

RESUMO

The atmospheric concentration of the potent greenhouse gases methane and nitrous oxide (N2O) has increased drastically during the last century. Methylomirabilis bacteria can play an important role in controlling the emission of these two gases from natural ecosystems, by oxidizing methane to CO2 and reducing nitrite to N2 without producing N2O. These bacteria have an anaerobic metabolism, but are proposed to possess an oxygen-dependent pathway for methane activation. Methylomirabilis bacteria reduce nitrite to NO, and are proposed to dismutate NO into O2 and N2 by a putative NO dismutase (NO-D). The O2 produced in the cell can then be used to activate methane by a particulate methane monooxygenase. So far, the metabolic model of Methylomirabilis bacteria was based mainly on (meta)genomics and physiological experiments. Here we applied a complexome profiling approach to determine which of the proposed enzymes are actually expressed in Methylomirabilis lanthanidiphila. To validate the proposed metabolic model, we focused on enzymes involved in respiration, as well as nitrogen and carbon transformation. All complexes suggested to be involved in nitrite-dependent methane oxidation, were identified in M. lanthanidiphila, including the putative NO-D. Furthermore, several complexes involved in nitrate reduction/nitrite oxidation and NO reduction were detected, which likely play a role in detoxification and redox homeostasis. In conclusion, complexome profiling validated the expression and composition of enzymes hypothesized to be involved in the energy, methane and nitrogen metabolism of M. lanthanidiphila, thereby further corroborating their unique metabolism involved in the environmentally relevant process of nitrite-dependent methane oxidation.


Assuntos
Bactérias Anaeróbias/enzimologia , Proteínas de Bactérias/metabolismo , Metano/química , Complexos Multienzimáticos/metabolismo , Nitratos/química , Óxido Nítrico/química , Metano/metabolismo , Nitratos/metabolismo , Óxido Nítrico/metabolismo , Oxirredução , Oxigenases/metabolismo
13.
Environ Sci Pollut Res Int ; 26(28): 28808-28816, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31377926

RESUMO

The effect of Mn powder addition on the simultaneous removal of SO2 and NO coupled with FeII(EDTA) absorption was investigated in this work. In the NO absorption system with FeII(EDTA), SO2 reduced FeII(EDTA)-NO to FeII(EDTA) with a reduction efficiency reaching 88.5% under the conditions of 4000 mg/m3 SO2, pH 8.0, 44 °C, and the flow rate of 1.2 L/min within 60 min. Introducing 0.1 M Mn powder with SO2 increased the FeII(EDTA)-NO reduction efficiency to 96.8% within 5 min. SO2 was also removed by reducing FeII(EDTA)-NO and converted into SO42- at a removal efficiency of 100%. After adding Mn powder, NO was removed through the following reaction: [Formula: see text]. Mn powder functioned as a reductant to regenerate the absorption of solution, and the coordinated NO in FeII(EDTA)-NO was reduced to NH4+. The resource utilization rate of N reached approximately 77.2%. The integrated technology is a potential solution for flue gas treatment in industrial sectors with coal-fired power plants and industrial boiler. Graphical abstract.


Assuntos
Ácido Edético/química , Compostos Ferrosos/química , Manganês/química , Óxido Nítrico/isolamento & purificação , Dióxido de Enxofre/isolamento & purificação , Ácido Edético/análise , Compostos Ferrosos/análise , Óxido Nítrico/química , Pós , Dióxido de Enxofre/química
14.
Int J Mol Sci ; 20(16)2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31416223

RESUMO

The conversion reaction of NO to NO3- ion catalyzed by the end-on [Cr(III)(n-TMC)(O2)(Cl)]+ superoxo and side-on [Cr(IV)(n-TMC)(O2)(Cl)]+ peroxo non-heme complexes (n = 12, 13, 14 and 15), which are biomimetic systems of nitric oxide dioxygenases (NODs), has been explored using a computational protocol in the framework of density functional theory. Results show that the potential energy profiles for the studied reactions lie above the reagent energies, regardless of the used catalyst. Both the O-O bond breaking in the biomimetics and the NO3- ion formation require low energy barriers suggesting an efficient catalytic power of the studied systems. The rate-determining step depends on ligand size.


Assuntos
Biomimética , Cromo/química , Óxido Nítrico/química , Oxirredução , Catálise , Teoria da Densidade Funcional , Modelos Moleculares , Estrutura Molecular , Oxigenases/química
15.
Chemphyschem ; 20(19): 2451-2460, 2019 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-31365183

RESUMO

Computer simulation studies of the molecular basis for ligand migration in proteins allow the description of key events such as the transition between docking sites, displacement of existing ligands and solvent molecules, and open/closure of specific "gates", among others. In heme proteins, ligand migration from the solvent to the active site preludes the binding to the heme iron and triggers different functions. In this work, molecular dynamics simulations, a Markov State Model of migration and empirical kinetic equations are combined to study the migration of O2 and NO in two truncated hemoglobins of Mycobacterium tuberculosis (Mt-TrHbN and Mt-TrHbO). For Mt-TrHbN, we show that the difference in the association constant in the oxy and deoxy states relies mainly in the displacement of water molecules anchored in the distal cavity in the deoxy form. The results here provide a valuable approach to study ligand migration in globins.


Assuntos
Hemoglobinas/química , Cadeias de Markov , Simulação de Dinâmica Molecular , Sítios de Ligação , Cinética , Ligantes , Mycobacterium tuberculosis/química , Óxido Nítrico/química , Oxigênio/química
16.
Environ Sci Pollut Res Int ; 26(29): 29660-29668, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31402436

RESUMO

Alkali metal chlorides emitted from sintering flue gas are easily adsorbed on the surface of activated carbon (AC) in the purification process. In this paper, NaCl particles adsorbing onto AC were simulated by impregnation method, and the size and morphology of NaCl particles were similar to those of NaCl-PM10 emitted from sintering flue gas. With the adsorption of NaCl particles, 2-10-µm pores of AC were filled, and the specific surface area of AC decreased. But NaCl led to the increase of acidic functional groups on the surface of AC. When 0.75 wt% NaCl was adsorbed, it was beneficial for AC catalytic denitration (de-NOx), because the chemical reaction was strengthened by acidic functional groups, so it showed a certain promotion of de-NOx efficiency. As 1.5 wt% NaCl and 3 wt% NaCl were adsorbed, NaCl had an inhibitory effect on AC de-NOx, which was because the specific surface area of AC decreased, and the prevention of physical adsorption played a major role. As a result, the de-NOx efficiency of AC adsorbed with 3 wt% NaCl decreased from 40.59 to 23.02% at 150 °C. Therefore, the absorption of NaCl fine particles on AC should not exceed 0.75 wt%.


Assuntos
Poluentes Atmosféricos/química , Carvão Vegetal/química , Gases/química , Cloreto de Sódio/química , Adsorção , Poluentes Atmosféricos/isolamento & purificação , Catálise , Resíduos Industriais , Óxido Nítrico/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
17.
Biosens Bioelectron ; 143: 111606, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466049

RESUMO

A disposable gas-sensing paper-based device (gPAD) was fabricated in origami design which integrates the gas adsorbent and the electrochemical detection zone in a single device. The gPAD for the determination of NOx gas uses a screen-printed graphene electrode modified with copper nanoparticles (CuNP/SPGE) to achieve high sensitivity and selectivity. The gPAD detects both, NO and NO2 (as NOx) with same current responses. The measurement could be performed directly through differential pulse voltammetry (DPV) with a detection limit as low as 0.23 vppm and 0.03 vppm with exposure times of 25 min and 1 h, respectively. The reproducibility in terms of relative standard deviation was less than 5.1% (n = 7 devices) at 25, 75 and 125 vppm NO2 and the life-time of this device was more than 30 days. The gPAD was applied to detect NOx in air and exhaust gases from cars. In comparison with spectrophotometry, there are no significant differences between both methods using a paired t-test of the results on a 95% confidence level. The designed gPAD can provide a new template model for other gas sensors with features of disposability and portability for fieldwork analysis at low cost.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Óxido Nítrico/isolamento & purificação , Dióxido de Nitrogênio/isolamento & purificação , Cobre/química , Grafite/química , Humanos , Nanopartículas Metálicas/química , Óxido Nítrico/química , Dióxido de Nitrogênio/química , Papel
18.
Biomater Sci ; 7(8): 3438-3449, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31268063

RESUMO

In medical device design, there is a vital need for a coating that promotes treatment of the patient and simultaneously prevents fouling by biomacromolecules which in turn can progress to infections, thrombosis, and other device-related complications. In this work, hydrophobin SC3 (SC3), a self-assembling amphiphilic protein, was coated on a nitric oxide (NO) releasing medical grade polymer to provide an antifouling layer to work synergistically with NO's bactericidal and antiplatelet activity (SC3-NO). The contact angle of SC3 samples were ∼30% lesser than uncoated control samples and was maintained for a month in physiological conditions, demonstrating a stable, hydrophilic coating. NO release characteristics were not adversely affected by the SC3 coating and samples with SC3 coating maintained NO release. Fibrinogen adsorption was reduced over tenfold on SC3 coated samples when compared to non-SC3 coated samples. The viable cell count of adhered bacteria (Staphylococcus aureus) on SC3-NO was 79.097 ± 7.529% lesser than control samples and 49.533 ± 18.18% lesser than NO samples. Platelet adherence on SC3-NO was reduced by 73.407 ± 14.59% when compared to control samples and 53.202 ± 25.67 when compared to NO samples. Finally, the cytocompatibility of SC3-NO was tested and proved to be safe and not trigger a cytotoxic response. The overall favorable results from the physical, chemical and biological characterization analyses demonstrate the novelty and importance of a naturally-produced antifouling layer coated on a bactericidal and antiplatelet polymer, and thus will prove to be advantageous in a multitude of medical device applications.


Assuntos
Biomimética/instrumentação , Proteínas Fúngicas/química , Óxido Nítrico/química , Polímeros/química , Polímeros/farmacologia , Adsorção , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Plaquetas/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Cinética , Camundongos , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície
19.
Molecules ; 24(15)2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31344907

RESUMO

In plants, much like in animals, nitric oxide (NO) has been established as an important gaseous signaling molecule. However, contrary to animal systems, NO-sensitive or NO-responsive proteins that bind NO in the form of a sensor or participating in redox reactions have remained elusive. Here, we applied a search term constructed based on conserved and functionally annotated amino acids at the centers of Heme Nitric Oxide/Oxygen (H-NOX) domains in annotated and experimentally-tested gas-binding proteins from lower and higher eukaryotes, in order to identify candidate NO-binding proteins in Arabidopsis thaliana. The selection of candidate NO-binding proteins identified from the motif search was supported by structural modeling. This approach identified AtLRB3 (At4g01160), a member of the Light Response Bric-a-Brac/Tramtrack/Broad Complex (BTB) family, as a candidate NO-binding protein. AtLRB3 was heterologously expressed and purified, and then tested for NO-response. Spectroscopic data confirmed that AtLRB3 contains a histidine-ligated heme cofactor and importantly, the addition of NO to AtLRB3 yielded absorption characteristics reminiscent of canonical H-NOX proteins. Furthermore, substitution of the heme iron-coordinating histidine at the H-NOX center with a leucine strongly impaired the NO-response. Our finding therefore established AtLRB3 as a NO-interacting protein and future characterizations will focus on resolving the nature of this response.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Óxido Nítrico/metabolismo , Proteínas de Arabidopsis/química , Sítios de Ligação , Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Heme/química , Heme/metabolismo , Modelos Moleculares , Conformação Molecular , Complexos Multiproteicos , Óxido Nítrico/química , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Transdução de Sinais , Análise Espectral , Relação Estrutura-Atividade
20.
Chemosphere ; 234: 302-309, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31228832

RESUMO

The catalytic gas-phase H2O2 oxidation of NO was achieved over Fe-based catalysts supported on montmorillonite K10, γ-alumina and ZSM-5. ESR tests illustrate that the three catalysts can catalyze decomposition of H2O2 yielding highly reactive hydroxyl radicals, of which Fe/K10 has the fastest rate, followed by Fe/γ-alumina. Fe3+ in Fe/K10 and Fe/γ-alumina show lower density of electron cloud due to a strong interaction between Fe3+ and the support, which benefits the electron transfer from the H2O2 to Fe3+, thus favoring the production of hydroxyl radicals. Fe species exist on the surface of Fe/K10 mainly in the form of Fe2O3, whereas Fe species of Fe/γ-alumina and Fe/ZSM-5 exist mainly in the form of Fe3O4, and it is found that Fe2O3 is more active than Fe3O4 in catalytic gas-phase H2O2 oxidation of NO. Interestingly, Fe/ZSM-5 has the lowest efficiency in generating hydroxyl radicals, its NO removal efficiency is 90%, which is much higher than 47.5% for Fe/γ-alumina and 62.3% for Fe/K10. In-situ IR results suggested that Fe/ZSM-5 are dual functional in oxidation of NO, that is, whether both Fe ion sites and Brønsted acid sites collectively provide the catalytic functionality. In the meantime, a possible reaction mechanism on catalytic gas-phase H2O2 oxidation of NO over Brønsted acid sites is proposed.


Assuntos
Óxido de Alumínio/química , Bentonita/química , Peróxido de Hidrogênio/química , Ferro/química , Óxido Nítrico/química , Zeolitas/química , Catálise , Gases , Oxirredução
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