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1.
Water Sci Technol ; 80(3): 397-407, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596251

RESUMO

In this work, the study of copper particles deposition on to carbon felt was presented by pulse electrodeposition method to electrochemically degrade methyl iodide (CH3I, 1 mg L-1) in aqueous solution. In order to solve the problems linked to the heterogeneous potential distribution in the 3-D porous structure, which lead to the so-called 'black core', we successfully used low concentration of copper salt (1 mM) and negative deposition potential (-2.5 V) to obtain Cu-nanoparticles/carbon felt (Cu-nano/CF) electrode, the copper coating improved the specific surface area of carbon felt from ∼0.07 to 0.7 m2 g-1 with high catalytic activity. Results show that 98.1% of CH3I can be removed with the Cu-nano/CF electrode in 120 min.


Assuntos
Cobre , Hidrocarbonetos Iodados/química , Resíduos Radioativos , Poluentes Radioativos da Água/química , Carbono/química , Fibra de Carbono/química , Poluentes Radioativos da Água/análise
2.
Medicine (Baltimore) ; 98(36): e16935, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31490376

RESUMO

BACKGROUND: Although several previous studies demonstrated the feasibility and efficacy of indocyanine green (ICG) for thyroid cancer surgery, ICG was administered through venous injection and focused on parathyroid gland protection. We thus aimed to study the feasibility of imaging using ICG combined with carbon nanoparticles (CNs) in the identification of sentinel lymph nodes (SLNs) in patients diagnosed with papillary thyroid microcarcinoma (PTMC). METHODS: Two approaches were applied to detect lymph nodes in PTMC surgery. Patients were randomized into 2 groups. ICG and CNs were injected into the thyroid in Group A. In Group B, only CNs was injected. Black-stained or fluorescent nodes observed using near-infrared fluorescence imaging systems were defined as SLNs. SLN and central lymph node (CLN) dissection was completed in both groups. The pathological and postoperative outcomes were compared between 2 groups. RESULTS: There were 40 patients in Group A and 60 in Group B. A total of 138 SLNs were identified; 72 and 66 SLNs were detected and dissected in Groups A and B, respectively. The number of SLNs identified (per patient) in Group A was higher than that in Group B (P = .027). The number of harvested CLNs was 161 and 192 in Groups A and B, respectively, out of which 45 and 48 lymph nodes with metastasis were confirmed by permanent pathology. The CLN metastatic rate in Group A was higher than that in Group B (P = .048). CONCLUSION: Imaging using ICG combined CNs is feasible and safe for SLN identification in PTMC patients. Compared with using only CNs, more SLNs can be removed and more metastatic lymph nodes can be confirmed when using the combined method. Although the combined method appears to accurately stage tumors, further research is needed.


Assuntos
Carbono/administração & dosagem , Carcinoma Papilar/patologia , Verde de Indocianina/administração & dosagem , Excisão de Linfonodo/métodos , Nanopartículas/administração & dosagem , Linfonodo Sentinela/cirurgia , Neoplasias da Glândula Tireoide/patologia , Adulto , Carbono/química , Carcinoma Papilar/cirurgia , Corantes/administração & dosagem , Estudos de Viabilidade , Feminino , Humanos , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Nanopartículas/química , Imagem Óptica/métodos , Linfonodo Sentinela/patologia , Neoplasias da Glândula Tireoide/cirurgia , Tireoidectomia/métodos
3.
Phys Chem Chem Phys ; 21(37): 20628-20640, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31495862

RESUMO

Methionine synthase (MetH) is a methylcobalamin (MeCbl)-dependent mammalian enzyme which plays a critical role in carrying out the transfer of a methyl group from methyl tetrahydrofolate to homocysteine to generate methionine and tetrahydrofolate. This catalytic cycle proceeds via cleavage of a Co-C bond which is formally heterolytic. This cleavage results in a structural change in the MeCbl cofactor bound to an enzyme. Unlike the native catalysis, upon photoexcitation, the Co-C bond in MeCbl-bound MetH generates the Co(ii)/CH3 radical pairs (RPs). Protein residues of the cap domain, particularly phenylalanine708 (F708) and leucine 715 (L715), which surrounds the upper face of the MeCbl cofactor, inhibit the photolysis of MeCbl by caging the CH3 radical and inducing the geminate recombination of the Co(ii)/CH3 RP. A molecular-level understanding of these effects requires a detailed investigation of the low-lying electronic states. Toward this, we have mutated the F708 residue with alanine (A708) and constructed the potential energy surfaces (PESs) for the low-lying S1 electronic state using a combined quantum mechanics/molecular mechanics (QM/MM) approach. The S1 PESs for the wild-type (WT) and mutant enzymes are the result of crossing of two electronic states, namely metal-to-ligand charge transfer (MLCT) and ligand field (LF) states, indicated by a seam. It is shown that the topologies of the S1 PESs are significantly modulated by introducing a mutation at the F708 position. Specifically, for the WT enzyme, the energy barrier of photoreaction and the energy difference between MLCT and LF minima are markedly higher than those of its mutant counterpart. Moreover, mutation influences the photoactivation of the Co-C bond in enzyme-bound MeCbl by decreasing the rate of geminate recombination and altering the rate of radical pair formation. This theoretical insight was also compared with transient absorption spectroscopic (TAS) studies which are in good agreement with the present findings.


Assuntos
5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/genética , Carbono/química , Cobalto/química , Vitamina B 12/análogos & derivados , 5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/metabolismo , Modelos Químicos , Estrutura Molecular , Mutação/genética , Fotólise , Domínios Proteicos/genética , Vitamina B 12/metabolismo
4.
Analyst ; 144(17): 5108-5116, 2019 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-31373337

RESUMO

We report here the influence of antibody immobilization strategy for protein immunosensors on screen printed carbon electrode arrays in terms of antibody binding activity, analytical sensitivity, limit of detection, and stability. Horseradish peroxidase (HRP) was the model analyte with anti-HRP immobilized on the sensors, and HRP activity was used for detection. Covalently immobilized anti-HRP antibodies on electrodes coated with chitosan, electrochemically reduced graphene oxide (rGO), and dense gold nanoparticle (AuNP) films had only 20-30% of the total immobilized antibodies active for binding. Active antibodies increased to 60% with passively adsorbed antibodies on bare electrodes, to 85% with oriented antibodies using protein A covalently immobilized on AuNP-coated carbon electrode, and to 98% when attached to protein A passively adsorbed onto bare electrodes. Passively adsorbed antibodies on bare electrodes lost activity in 1-2 days, but antibodies immobilized using other strategies remained relatively stable after 5 days. Covalent immobilization gave limits of detection (LOD) of 40 fg mL-1, while passively adsorbed antibodies or protein A on carbon electrodes had LODs 4-8 fg mL-1, but were unstable. Sensitivity was highest for antibodies covalently attached to AuNP electrodes (2.40 nA per log pg per mL) that also had highest antibody coverage, and decreased slightly when protein A on AuNP was used to orient antibodies. Passively adsorbed antibodies and oriented antibodies on protein A gave slightly lower sensitivities. Immobilization strategy or antibody orientation did not have a significant effect on LOD, but dynamic range increased as the number of active antibodies on sensor surfaces increased.


Assuntos
Anticorpos Imobilizados/química , Carbono/química , Técnicas Biossensoriais/métodos , Quitosana/química , Técnicas Eletroquímicas/métodos , Eletrodos , Grafite/química , Peroxidase do Rábano Silvestre/química , Imunoensaio/métodos , Limite de Detecção , Oxirredução , Propriedades de Superfície
5.
Food Chem ; 300: 125178, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31326677

RESUMO

In this work, a sensitive and stable ZrO2-Cu(I) nanosphere mesoporous material modified non-enzymatic glucose sensor has been developed through simple, low cost chemistry. ZrO2-Cu(I) material was obtained by controlled co-precipitation method under ultra dilution conditions. Cyclic voltammetric tests were performed in order to evaluate the electrocatalytic activity ZrO2-Cu(I) modified electrode. The modified electrode showed high sensitivity, wide linear range and very low detection limit of 0.25 mM, this indicates that the modified sensor is competent with that reported earlier. Spherical morphology of the active material, alkaline environment and presence of +1 copper have significantly enhanced the electro-catalytic oxidation of glucose on carbon paste platform. Also, the fabricated electrode showed excellent anti-interference nature. Electro-catalytic oxidation of glucose was demonstrated in real raw unpurified orange juice, this shows the selective electrocatalytic activity of the ZrO2-Cu(I) nanosphere material towards glucose even in the presence of interferrants.


Assuntos
Citrus sinensis/química , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Glucose/análise , Carbono/química , Catálise , Cobre/química , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Sucos de Frutas e Vegetais/análise , Glucose/química , Limite de Detecção , Nanosferas/química , Oxirredução , Zircônio/química
6.
Chem Commun (Camb) ; 55(65): 9653-9656, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31342021

RESUMO

The fast and accurate real-time monitoring of hydrogen peroxide (H2O2) secreted from living cells plays a critical role in clinical diagnosis and management. Herein, we report low-cost and self-supported MoS2 nanosheet arrays for non-enzymatic eletrochemical H2O2 detection. Under the optimal test conditions, such MoS2 electrodes exhibit extremely promising electrocatalytic performance with a low detection limit of 1.0 µM (S/N = 3) and an excellent sensitivity of 5.3 mA mM-1 cm-2. Furthermore, the detection of the trace amount of H2O2 secreted from live A549 cancer cells was successfully performed with this biosensor.


Assuntos
Dissulfetos/química , Peróxido de Hidrogênio/análise , Molibdênio/química , Nanoestruturas/química , Células A549 , Técnicas Biossensoriais/métodos , Carbono/química , Dissulfetos/síntese química , Técnicas Eletroquímicas/métodos , Humanos , Limite de Detecção
8.
Bioresour Technol ; 291: 121838, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31344635

RESUMO

Replacing fossil energy by utilizing biomass as carbon source to convert metal oxides has meaning for reduction of minerals. Microwave pyrolysis of walnut shell for reduction process of low-grade pyrolusite was proposed. Thermogravimetric analysis indicated biomass pyrolysis process for reduction of pyrolusite was divided into four phases identified by temperatures: dehydration stage (<150 °C), pre-pyrolysis stage (150 °C-290 °C), curing decomposition stage (290 °C-480 °C) and carbonization stage (>480 °C), and manganese recovery reached 92.01% at 650 °C for 30 min with 18% walnut shell. The strongest preferential orientation of MnO was appeared, with good crystalline structure and no MnO2 and FeO peaks detected. The product surface became loose and porous with numerous cracks, pits and holes, and molten granules were interconnected and stacked with regular shape. The methods propose new idea of selective reduction of pyrolusite based on biomass pyrolysis by microwave heating.


Assuntos
Juglans/química , Biomassa , Carbono/química , Temperatura Alta , Compostos de Manganês/química , Micro-Ondas , Óxidos/química , Pirólise
9.
Chem Biodivers ; 16(8): e1900205, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31294527

RESUMO

The importance of phenolic compounds for responding to various environmental conditions has been widely emphasized. However, the role of interactions between polyphenols and ecological factors, especially C, N, and P stoichiometry was little studied. Here, 15 sites across five provinces of Pinus bungeana in temperate regions of China were studied. The results showed that the higher values of total phenolic contents (TPC) of leaf and litter were distributed among the north distribution area of P. bungeana, lower values were in the south, whereas soil TPC were contrary to leaf and litter TPC. The stepwise regression, path analysis and decision index of path analysis for leaf TPC and ecological factors showed that altitude had the most direct impact on leaf TPC. Moreover, the principal determinants of leaf, litter and soil TPC were soil C/P ratios, longitude, and soil N/P ratios, respectively. In addition, the leaf, litter and soil TPC of P. bungeana were limited by soil C/N ratios, mean annual temperature, and soil P, respectively. Overall, our study provided evidence that ecological factors affected strongly the leaf, litter and soil TPC of P. bungeana.


Assuntos
Pinus/química , Polifenóis/química , Solo/química , Carbono/química , China , Colorimetria , Ecossistema , Nitrogênio/química , Fósforo/química , Pinus/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Polifenóis/análise , Temperatura Ambiente
10.
Bioresour Technol ; 291: 121855, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31357042

RESUMO

The aim of the present work was to compare corn stalk (CS) and cow manure (CM) for hydrochar production at different reaction temperatures (180-260 °C) and retention times (1-4 h). CM and CS resulted in hydrochars with significantly different physicochemical properties; however, both led to similar yields (30-65%). CM-derived hydrochar had a lower carbon content but a higher nitrogen and ash content than CS-derived hydrochar. CM-derived hydrochar demonstrated potential as a soil amendment due to its higher content of nitrogen, the presence of surface functional groups and higher specific surface area in comparison to CS-derived hydrochar. In comparison, CS-derived hydrochar demonstrated suitability as a solid fuel due to its high heating value and low ignition temperature. This study revealed that the composition of lignocellulose significantly impacted the properties and thus potential applications of hydrochar.


Assuntos
Carvão Vegetal/metabolismo , Esterco , Zea mays/química , Animais , Carbono/química , Carbono/metabolismo , Bovinos , Nitrogênio/metabolismo , Solo
11.
J Agric Food Chem ; 67(28): 8035-8044, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31282154

RESUMO

The simultaneous detection of multiple mycotoxins is important due to the increased toxic effects of combined mycotoxins in grains. In this research, a combination of modified QuEChERS with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for simultaneous detection of 20 mycotoxins in grains. A series of different types of magnetic (Fe3O4) nanoparticles modified with multiwalled carbon nanotubes (Fe3O4-MWCNTs) were designed as modified QuEChERS adsorbents for facile and efficient purification and for target interferences removal in the matrices. When there is an external magnetic field, the proposed modified QuEChERS method uses a shorter pretreatment time compared with the traditional QuEChERS method, which makes it possible to conduct high-throughput analyses. To optimize the QuEChERS process, the extraction solvent and the type and amount of the Fe3O4-MWCNTs were investigated. Under optimal conditions, the method was validated and showed satisfactory linearity (r2 ≥ 0.9965), good recovery (73.5-112.9%), good precision (1.3-12.7%), and excellent sensitivity (ranging from 0.0021 to 5.4457 ng g-1), which indicates that this method can be used for detecting multiple mycotoxins in real samples.


Assuntos
Carbono/química , Cromatografia Líquida de Alta Pressão/métodos , Grão Comestível/química , Micotoxinas/química , Micotoxinas/isolamento & purificação , Nanotubos/química , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Adsorção , Magnetismo , Extração em Fase Sólida/instrumentação
12.
Ying Yong Sheng Tai Xue Bao ; 30(6): 1877-1884, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31257759

RESUMO

Priming effect is one of the important mechanisms regulating soil organic matter decomposition. However, the variation of priming effects in different soil layers remains unclear. In this study, we conducted a 30-day incubation experiment using no-tillage black soil from northeastern China. 13C-glucose and dynamic CO2 trapping methods were employed to investigate soil organic carbon (SOC) mineralization rates and the priming effect of the added 13C-glucose in the upper soil layer (0-10 cm) and the lower soil layer (30-40 cm). Our results showed that the cumulative SOC-specific mineralization rate in the upper layer was similar to that in the lower layer soil without glucose addition. Glucose addition significantly altered the mineralization rates in both layers, resulting in a positive priming effect (36.7%) in the upper layer but a negative priming effect (-12.4%) in the lower layer. The cumulative priming effect during the 30-day incubation was 3.24 mg C·g-1 SOC for the upper layer soil and -1.24 mg C·g-1 SOC for the lower layer soil. There was still a net SOC increase, even with positive priming effects in the upper layer soil. This was due to considerable amount of added glucose-C remained un-mineralized in the soil which would compensate the carbon loss from priming effects. Overall, our results demonstrated that the magnitude and direction of priming effects might differ between soil layers. Our findings contribute to a better understanding of the effects of conservation tillage practices (no-tillage and straw incorporation) on soil organic matter dynamics in agroecosystems.


Assuntos
Agricultura , Carbono/química , Solo/química , China , Microbiologia do Solo
13.
J Photochem Photobiol B ; 197: 111545, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31326847

RESUMO

Proper waste utilization in order to promote value added product is a promising scientific practice in recent era. Inspiring from the recurring trend, we propose a single step oxidative pyrolysis derived fluorescent carbon dots (C-dots) from Allium sativum peel, which is a natural, nontoxic, and waste raw material. Because of its excellent optical properties, and photostability this C-dots have been used in versatile area of applications. Due to its immediate water dispersing character, C-dots reinforced Poly(acrylic acid) (PAA) films revealed improvement in uniaxial stretching behavior and can be used as transparent sunlight conversion film. The nanocomposite film has been tested against rigorous simulated sunlight which proved almost identical sunlight conversion behavior with no photo-bleachable character which is definitely added an extra quality of transparent polymer films. Moreover, the C-dots dispersion has been used as in vitro biomarker for living cells owing to its ease in solubility, biocompatibility, non-cytotoxicity and bright fluorescence even in subcutaneous environment. For this case, adipose derived mesenchymal stem cells (ADMSCs) have been chosen and injected to rabbit ear skin to perform two-photon imaging experiment. The present work opens a new avenue towards the large-scale synthesis of bio-waste based fluorescent C-dots, paving the way for their versatile applications.


Assuntos
Allium/química , Nitrogênio/química , Fotodegradação/efeitos da radiação , Pontos Quânticos/química , Enxofre/química , Luz Solar , Resinas Acrílicas/química , Tecido Adiposo/citologia , Allium/metabolismo , Animais , Materiais Biocompatíveis/química , Carbono/química , Sobrevivência Celular/efeitos dos fármacos , Frutas/química , Frutas/metabolismo , Química Verde , Masculino , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Coelhos , Pele/efeitos dos fármacos , Pele/patologia , Solubilidade
14.
Top Curr Chem (Cham) ; 377(4): 20, 2019 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-31273478

RESUMO

Form a green and sustainable chemistry point of view, cross-dehydrogenative coupling (or oxidative cross-coupling) reactions have been recognized as environmentally sustainable and atom economical synthetic routes for the construction of new carbon-carbon and carbon-heteroatom bonds, since no pre-functionalization of starting materials is required. In the past few years, the direct coupling of sp-hybridized C-H bonds with heteroatom-H bonds has received much attention because of the importance of heteroatom-substituted alkynes in organic and medicinal chemistry. This review examines the recent developments in cross-dehydrogenative coupling reactions between C(sp)-H and X-H (X = N, P, S, Si, Sn) bonds, with a particular focus on the mechanistic aspects of the reactions.


Assuntos
Alquinos/química , Carbono/química , Hidrogênio/química , Hidrogenação , Nitrogênio/química , Fósforo/química , Silício/química , Enxofre/química , Estanho/química
15.
Int J Nanomedicine ; 14: 4867-4880, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31308663

RESUMO

Background: The demand for an effective vaccine delivery system that drives a suitable immune response is increasing. The oxidized carbon nanosphere (OCN), a negatively charged carbon nanoparticle, has the potential to fulfill this requirement because it can efficiently deliver macromolecules into cells and allows endosomal leakage. However, fundamental insights into how OCNs are taken up by antigen-presenting cells, and the intracellular behavior of delivered molecules is lacking. Furthermore, how immune responses are stimulated by OCN-mediated delivery has not been investigated. Purpose: In this study, the model protein antigen ovalbumin (OVA) was used to investigate the uptake mechanism and intracellular fate of OCN-mediated delivery of protein in macrophages. Moreover, the immune response triggered by OVA delivered by OCNs was characterized. Methods: Bone-marrow-derived macrophages (BMDMs) from mice were used to study antigen uptake and intracellular trafficking. Mice were immunized using OCN-OVA combined with known adjuvants, and the specific immune response was measured. Results: OCNs showed no cytotoxicity against BMDMs. OCN-mediated delivery of OVA into BMDMs was partially temperature independent process. Using specific inhibitors, it was revealed that intracellular delivery of OCN-OVA does not rely on phagocytosis or the clathrin- and lipid raft/caveolae-mediated pathways. Delivered OVA was found to colocalize with compartments containing MHC class I, but not with early endosomes, lysosomes, and autophagosomes. Immunization of OVA using OCNs in combination with the known adjuvant monophosphoryl lipid A specifically enhanced interferon gamma (IFNγ)- and granzyme B-producing cytotoxic T cells (CTLs). Conclusion: OCNs effectively delivered protein antigens into macrophages that localized with compartments containing MHC class I partially by the temperature independent, but not clathrin- and lipid raft/caveolae-mediated pathways. Increased CD8+ T-cell activity was induced by OCN-delivered antigens, suggesting antigen processing toward antigen presentation for CTLs. Taken together, OCNs are a potential protein antigen delivery system that stimulates the cell-mediated immune response.


Assuntos
Antígenos/administração & dosagem , Carbono/química , Sistemas de Liberação de Medicamentos , Imunidade Celular , Nanopartículas/química , Adjuvantes Imunológicos/farmacologia , Animais , Antígenos/imunologia , Autofagossomos/efeitos dos fármacos , Autofagossomos/metabolismo , Linhagem Celular , Endocitose/efeitos dos fármacos , Endossomos/efeitos dos fármacos , Endossomos/metabolismo , Feminino , Imunidade Celular/efeitos dos fármacos , Cinética , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Camundongos Endogâmicos BALB C , Nanopartículas/toxicidade , Oxirredução , Linfócitos T Citotóxicos/efeitos dos fármacos , Linfócitos T Citotóxicos/imunologia
16.
Phytochemistry ; 166: 112075, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31351332

RESUMO

Isoflavonoids are one of the most important groups of naturally occurring antioxidants. Their structural features are important for evaluating their antioxidative activity. In this work, density functional theory (DFT) methods were applied to investigate the influence of the C2=C3 double bond on the antioxidative activity of isoflavonoids based on three currently accepted radical scavenging mechanisms from the viewpoint of thermodynamics. The C2=C3 double bond can make the compounds more flat, which would extend the conjugated system in the molecule and make the isoflavonoids higher antioxidant activity. The C2=C3 double bond would not alter the strongest antioxidative hydroxyl group of the isoflavonoids. In the gas, benzene and CHCl3 phases, the C2=C3 double bond will enhance the antioxidative activity of isoflavonoids by lowering the bond dissociation enthalpies of the hydroxyl groups in the B ring that are the strongest antioxidative sites for the hydrogen atom transfer (HAT) mechanism. In polar phases, a similar result is obtained by weakening the proton affinity of 7-OH that is the strongest antioxidative hydroxyl group in the sequential proton loss electron transfer (SPLET), mechanism. Thus, the C2=C3 double bond will enhance the antioxidative activity of isoflavonoids irrespective of the studied phases.


Assuntos
Antioxidantes/química , Carbono/química , Teoria da Densidade Funcional , Flavonoides/química , Solventes/química , Termodinâmica
17.
Chemistry ; 25(50): 11641-11645, 2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31338883

RESUMO

Ibuprofen was prepared from an inactive and inexpensive p-xylene by three-step flow functionalizations through chemoselective metalations of benzyl positions in sequence using an in situ generated LICKOR-type superbase. The flow approach in the microreactor facilitated the comprehensive exploration of over 100 conditions in the first-step reaction by varying concentrations, temperatures, solvents, and equivalents of reagents, enabling optimal conditions to be found with 95 % yield by significantly suppressing the formation of byproducts, followed by the second C-H metalation step in 95 % yield. Moreover, gram-scale synthesis of ibuprofen in the final step was achieved by biphasic flow reaction of solution-phase intermediate with CO2 , isolating 2.3 g for 10 min of operation time.


Assuntos
Ibuprofeno/química , Metais/química , Xilenos/química , Carbono/química , Hidrogênio/química , Ibuprofeno/síntese química , Tolueno/análogos & derivados , Tolueno/química
18.
Chemosphere ; 233: 890-895, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340416

RESUMO

The reduction of halocarbons by NADH models and NADH under ambient conditions is reported as a new type of reactivity pointing towards a hitherto unknown disruptive pathway for NADH/NADPH-dependent processes. The reaction was studied with the omnipresent pesticide DDT, the inhalation anesthetic halothane, and several simple halocarbons. The halide-hydride exchange represents a biochemical equivalent for the reduction of halocarbons by traditional synthetic reagents like silanes (R3Si-H) and stannanes (R3Sn-H). High precision thermochemical calculations (CBS-QB3) reveal the carbon-hydrogen bond dissociation energy of NADH (70.8 kcal·mol-1) to be lower than that of stannane (SnH4: 78.1 kcal·mol-1), approaching that of the elusive plumbane (PbH4: 68.9 kcal·mol-1). The ready synthetic accessibility of NADH models, their low carbon-hydrogen bond dissociation energy, and their dehalogenation activity in the presence of air and moisture recommend these compounds as substitutes for the air-sensitive or toxic metal hydrides currently employed in synthesis.


Assuntos
DDT/metabolismo , Poluentes Ambientais/metabolismo , Recuperação e Remediação Ambiental/métodos , Halotano/metabolismo , Hidrocarbonetos Halogenados/análise , Hidrocarbonetos Halogenados/metabolismo , NAD/metabolismo , Carbono/química , Hidrogênio/química , Ligações de Hidrogênio , Indicadores e Reagentes , Silanos/química , Compostos de Estanho/química
19.
Anal Chim Acta ; 1078: 125-134, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358210

RESUMO

We synthesized three kinds of nitrogen-doped nanoporous carbon nanomaterials (represented by N-mC) through a cost-effective method, that is, pyrolysis of plant biomasses (grass, flower, and peanut shells). We further explored their potential as sensitive bioplatforms for electrochemical label-free aptasensors to facilitate the early detection of alpha-fetoprotein (AFP). Chemical structure characterizations revealed that rich functional groups coexisted in as-synthesized N-mC nanomaterials, such as C-C, C-O, C=O, C-N, and COOH. Among the three kinds of N-mC nanomaterials, the one derived from grass (N-mCg) exhibited the lowest carbon defect degree, the highest ID/IG ratio in the Raman spectra, and the largest specific surface area (186.2 m2 g-1). Consequently, N-mCg displayed excellent electrochemical activity and strong affinity toward aptamer strands, further endowing the corresponding aptasensor with sensitive detection ability for AFP. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were used to investigate the whole detection procedure for AFP. The EIS and DPV results showed that the fabricated N-mCg-based aptasensor possessed an extremely low limit of detection of 60.8 and 61.8 fg·mL-1 (s/n = 3), respectively, for detecting AFP within a wide linear range from 0.1 pg mL-1 to 100 ng mL-1. Moreover, the aptasensor displayed acceptable selectivity and applicability, high reproducibility, and excellent stability in serum samples of cancer patients. Therefore, the proposed cost-effective and label-free strategy based on the nitrogen-doped nanoporous carbon derived from plant biomass is a promising approach for the early detection of various tumor markers.


Assuntos
Biomassa , Técnicas Biossensoriais/métodos , Carbono/química , Técnicas Eletroquímicas/métodos , Nanoestruturas/química , alfa-Fetoproteínas/análise , Adolescente , Adulto , Idoso , Aptâmeros de Nucleotídeos/química , Sequência de Bases , Técnicas Biossensoriais/instrumentação , DNA/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Feminino , Humanos , Limite de Detecção , Masculino , Pessoa de Meia-Idade , Nitrogênio/química , Plantas/química , Porosidade , Reprodutibilidade dos Testes , Adulto Jovem
20.
Anal Chim Acta ; 1078: 16-23, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31358214

RESUMO

The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10-500 µg mL-1 were obtained for both dexamethasone and prednisolone (r2 = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 µg mL-1, respectively, whereas the limits of quantification were 6.00 and 20.02 µg mL-1, respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection.


Assuntos
Cromatografia em Papel/métodos , Dexametasona/análise , Técnicas Eletroquímicas/métodos , Preparações Farmacêuticas/análise , Preparações de Plantas/análise , Prednisolona/análise , Carbono/química , Cromatografia em Papel/instrumentação , Contaminação de Medicamentos , Técnicas Eletroquímicas/instrumentação , Eletrodos , Limite de Detecção , Papel , Impressão Tridimensional
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