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1.
Chemosphere ; 260: 127577, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758784

RESUMO

Tungsten (W) occurrence and speciation was investigated in sediments collected from Fallon, Nevada where previous studies have linked elevated W levels in human body fluids to an unusual cluster of childhood leukemia cases. The speciation of sedimentary W was determined by µ-XRF mapping and µ-XANES. The W content of the analyzed surface sediments ranged between 81 and 25,908 mg/kg, which is significantly higher than the W content in deeper sediments which ranged from 37 to 373 mg/kg at 30 cm depth. The µ-XANES findings reveal that approximately 20-50% of the total W in the shallow sediment occurs in the metallic form (W0); the rest occurs in the oxide form (WVIO3). Because W0 does not occur naturally, its elevated concentrations in surface sediments point toward a possible local anthropogenic origin. The oxidation of metallic W0 with meteoric waters likely leads to the formation of WVIO3. The chief water-soluble W species was identified as WO42- by chromatographic separation and speciation modeling. These results led us to postulate that W0 particles from a currently unknown but local source(s) is (are) deposited onto the soils and/or surface sediments. The W0 in interaction with meteoric water is oxidized to WVIO3, and as these sediment-water interactions progress, WO42- is formed in the water at pH ∼7. Under pH < 7, and sufficient W concentrations, tungstate tends to polymerize, and polymerized species are less likely to adsorb onto sediments. Polymerized species have lower affinity than monomers, which leads to enhanced mobility of W.


Assuntos
Sedimentos Geológicos/química , Tungstênio/química , Adsorção , Concentração de Íons de Hidrogênio , Nevada , Solo/química , Síncrotrons , Compostos de Tungstênio/química , Espectroscopia por Absorção de Raios X
2.
Chemosphere ; 261: 127719, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758927

RESUMO

Conversion of aniline wastes to value-added products is always a promising method to treat aniline wastewater. In this study, a selective oxidation of aniline contaminants by Bi2·15WO6 was carried out under visible light and alkaline conditions. Kinetic results show that the oxidation rates of aniline increase with increasing pH values under visible light. UV-vis absorption spectra and GC-MS analysis confirm that azobenzene is the primary oxidation product with aminophenol and N,N'-diphenylhydrazine as the secondary products. The analyses from Mott-Schottky, electrochemical impedance spectroscopy (EIS), transient photocurrent and photoluminescence (PL) further indicate that OH- promotes the separation and transfer of photogenerated electron-hole pairs on the surface of Bi2·15WO6, thus facilitating oxidation of aniline. Quenching experiments and electron spin resonance (ESR) analysis confirm that h+ is the predominant specie in the Bi2·15WO6 system and aniline radical cation (PhNH2•+) is an important intermediate. The Hammett and ΔBDEN-H plots further reveal that e- abstraction from aniline with the formation of PhNH2•+, followed by H+ abstraction from PhNH2•+ with the formation of anilino radicals (PhNH•), is the prerequisite for the formation of N,N'-diphenylhydrazine, which is then oxidized to azobenzene via the hydrogen-abstraction pathway. This work provides a cost-effective method to selectively oxidize aniline to azobenzene.


Assuntos
Compostos de Anilina/química , Bismuto/química , Hidrogênio/química , Luz , Compostos de Tungstênio/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Catálise , Concentração de Íons de Hidrogênio , Cinética , Oxirredução , Fotoquímica , Águas Residuárias/química
3.
Food Chem ; 333: 127515, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32683260

RESUMO

The nutritional and commercial value of the sweet cherry provides it a great economic importance in Italy. The aim of this study was to characterize 35 sweet cherry cultivars and one of sour cherry, by analyzing values of different pomological and nutraceutical traits, identifying cultivars with antioxidant activity and total anthocyanins content closest to those present in literature for Ferrovia (largely diffused in Italy). To this goal, a multivariate metric index through the Soft Independent Modeling of Class Analogy analyzing an artificial dataset and testing a real one, two hierarchical clustering and a principal component analysis, were performed. The multivariate analyses result simultaneously investigated all the variables highlighting cvs. Sylvia, Graffione nero Col di Mosso, Ferrovia, Mora della Punta, Bianchetta Nuchis and Sandra to be more similar to literature data of Ferrovia. This matrix index was a useful tool, to select the most commercial promising varieties.


Assuntos
Algoritmos , Prunus avium/classificação , Antocianinas/análise , Antioxidantes/química , Análise por Conglomerados , Frutas/química , Frutas/metabolismo , Concentração de Íons de Hidrogênio , Itália , Molibdênio/química , Fenóis/análise , Extratos Vegetais/química , Análise de Componente Principal , Prunus avium/química , Prunus avium/metabolismo , Compostos de Tungstênio/química
4.
Food Chem ; 320: 126683, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32229401

RESUMO

Here, we demonstrate use of acetylcholinesterase (AChE)-responsive polyoxometalate (POM)/surfactant supramolecular spheres to build a liquid crystal (LC)-based sensing platform for detection of organophosphorus pesticides. The self-assembled spheres are composed of hybrid materials of a POM, sodium dodecatungstophosphate (PW12), and a surfactant, myristoylcholine (Myr). It displays dark appearance when the aqueous solution is in contact with LCs supported on the octadecyltrichlorosilane-treated glass deposited with the supramolecular spheres, suggesting perpendicular orientation of LCs at the aqueous/LC interface. In contrast, LCs show bright appearance when the surface-deposited supramolecular spheres are enzymatically hydrolyzed by AChE, corresponding to planar orientation of LCs at the aqueous/LC interface. Detection of organophosphates are successfully achieved as they are potent inhibitors of AChE. The detection limit of the sensing platform reached 0.9 ng/mL for dimethoate. This method can avoid disturbance of external interference with excellent specificity and sensitivity, which makes it very promise in detection of organophosphorus pesticides.


Assuntos
Acetilcolinesterase/metabolismo , Análise de Alimentos/métodos , Cristais Líquidos/química , Praguicidas/análise , Análise de Alimentos/instrumentação , Hidrólise , Lagos/análise , Limite de Detecção , Compostos Organofosforados/análise , Silanos/química , Tensoativos/química , Compostos de Tungstênio/química , Água/química , Poluentes Químicos da Água/análise
5.
Chemistry ; 26(51): 11900-11908, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32329538

RESUMO

The energetically viable fabrication of stable and highly efficient solid acid catalysts is one of the key steps in large-scale transformation processes of biomass resources. Herein, the covalent modification of the classical Dawson polyoxometalate (POMs) with sulfonic acids (-SO3 H) is reported by grafting sulfonic acid groups on the POM's surface followed by oxidation of (3-mercaptopropyl)trimethoxysilane. The acidity of TBA6 -P2 W17 -SO3 H (TBA=tetrabutyl ammonium) has been demonstrated by using 31 P NMR spectroscopy, clearly indicating the presence of strong Brønsted acid sites. The presence of TBA counterions renders the solid acid catalyst as a promising candidate for phase transfer catalytic processes. The TBA6 -P2 W17 -SO3 H shows remarkable activity and selectivity, excellent stability, and great substrate compatibility for the esterification of free fatty acids (FFA) with methanol and conversion into biodiesel at 70 °C with >98 % conversion of oleic acid in 20 min. The excellent catalytic performance can be attributed to the formation of a catalytically active emulsion, which results in a uniform catalytic behavior during the reaction, leading to efficient interaction between the substrate and the active sites of the catalyst. Most importantly, the catalyst can be easily recovered and reused without any loss of its catalytic activity owing to its excellent phase transfer properties. This work offers an efficient and cost-effective strategy for large-scale biomass conversion applications.


Assuntos
Ácidos/química , Ácido Oleico/química , Compostos de Tungstênio/química , Biocombustíveis , Biomassa , Catálise , Esterificação , Metanol/química , Ácidos Sulfônicos/química
6.
Food Chem ; 318: 126461, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32143129

RESUMO

A sensor consisting of an optical fibre with the exposed tip coated with the polyoxometalate salt [(C4H9)4N]4H[PMo10V2O40], specially designed to be insoluble in water, which UV-Vis spectrum changed in contact with formaldehyde, is presented. The sensor limit of detection for formaldehyde was 0.2 mg L-1, and the limit of quantification was 0.6 mg L-1, which were close to the conventional spectrophotometric method values of 0.2 mg L-1 and 0.5 mg L-1, respectively, and lower than the tolerable limit for ingested food. The sensor was tested for formaldehyde quantification in milk, as its deliberate addition is a matter of concern. The results obtained analysing formaldehyde in milk samples by the optical sensor and by the conventional method were not statistically different (α = 0.05).


Assuntos
Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Formaldeído/análise , Leite/química , Fibras Ópticas , Animais , Limite de Detecção , Óptica e Fotônica/instrumentação , Óptica e Fotônica/métodos , Compostos de Tungstênio/química , Água/química
7.
Chem Commun (Camb) ; 56(21): 3111-3114, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32090228

RESUMO

The peroxotungstate oxidation-mediated two-phase amplification system (POM-TPAS) is applied for the first time to the sensitive detection of locus-specific 5-hydroxymethylcytosine (5hmC) in DNA with low non-specific amplification. This strategy greatly shortens reaction time, improves sensitivity, and reduces non-specific amplification.


Assuntos
5-Metilcitosina/análogos & derivados , Compostos de Epóxi/química , Compostos de Tungstênio/química , 5-Metilcitosina/análise , DNA/química , DNA/genética , Humanos , Oxirredução
8.
Chemistry ; 26(26): 5799-5809, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32104951

RESUMO

The influence of the composition of chaotropic polyoxometalate (POM) anions on their affinity to biological systems was studied by means of atomistic molecular dynamics (MD) simulations. The variations in the affinity to hen egg-white lysozyme (HEWL) were analyzed along two series of POMs whereby the charge or the size and shape of the metal cluster are modified systematically. Our simulations revealed a quadratic relationship between the charge of the POM and its affinity to HEWL as a consequence of the parabolic growth of POM⋅⋅⋅water interaction with the charge. As the charge increases, POMs become less chaotropic (more kosmotropic) increasing the number and the strength of POM-water hydrogen bonds and structuring the solvation shell around the POM. This atomistic description explains the proportionally larger desolvation energies and less protein affinity for highly charged POMs, and consequently, the preference for moderate charge densities (q/M=0.33). Also, our simulations suggest that POM⋅⋅⋅protein interactions are size-specific. The cationic pockets of HEWL protein show a preference for Keggin-like structures, which display the optimal dimensions (≈1 nm). Finally, we developed a quantitative multidimensional model for protein affinity with predictive ability (r2 =0.97; q2 =0.88) using two molecular descriptors that account for the charge density (charge per metal atom ratio; q/M) and the size and shape (shape weighted-volume; VS ).


Assuntos
Ânions/química , Cátions/química , Muramidase/química , Compostos de Tungstênio/química , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Relação Estrutura-Atividade
9.
Anal Chim Acta ; 1099: 52-59, 2020 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-31986277

RESUMO

Structuring of noble metal nanoparticles on transition metal dichalcogenide nanosheets induces significantly enhanced electronic, optical, and catalytic functions. However, the synthesis of multifunctional hybrids is always time-consuming and involves multiple steps. Herein, a ternary Au nanoparticle-ferrocene-WS2 nanosheet (AFW) composite has been prepared by a facile one-step sonochemical approach. Stripped WS2 nanosheets were functionalized with ferrocene monocarboxylic acid (FMC) and gold nanoparticles (AuNPs) by making use of the strong coordinative interaction of carboxyl groups with tungsten atoms. The AuNPs decorating the WS2 nanosheet not only increase the water solubility of WS2 nanosheet and surface area of the modified electrode, but also act as electron transport bridges to aid the tunneling of electrons from the small redox molecule, FMC, through the space to the electrode on which they are mounted. Furthermore, the ternary AFW nanocomposite could effectively avoid the leaching of FMC from the nanocomposite matrix and provided a suitable environment for the immobilized biomolecules. Combining the immune magnetic beads technology and the AFW nanocomposite with aforementioned advantages, a high-performance electrochemical immunosensor was successfully developed using carbohydrate antigen 72-4 (CA72-4) as a model analyte. A linear relationship in the range of 2-50 U/L for the detection of CA72-4 was found with a low detection limit of 0.6 U/L. In addition, the biosensor showed excellent performance in selectivity, stability, and reproducibility. Thus, this work not only proposes a facile avenue for preparing a 2D WS2 nanocomposite with multifunctional properties but also opens up a new method to extend the application of WS2-based materials in biological sensing.


Assuntos
Antígenos Glicosídicos Associados a Tumores/sangue , Técnicas Biossensoriais , Técnicas Eletroquímicas , Imunoensaio , Ultrassom , Antígenos Glicosídicos Associados a Tumores/imunologia , Compostos Ferrosos/química , Ouro/química , Humanos , Nanopartículas Metálicas/química , Metalocenos/química , Nanocompostos/química , Sulfetos/química , Compostos de Tungstênio/química
10.
Molecules ; 25(3)2020 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-31991874

RESUMO

Polyoxometalate-based ionic liquid hybrid materials with a pyridinium cation, containing Brönsted acid sites, were synthesized and used as catalysts for the oxidation of model and real diesel fuels. Keggin-type polyoxometalates with the formulae [PMo12O40]3-, [PVMo11O40]4-, [PV2Mo10O40]4-, [PW12O40]3- were used as anions. It was shown that increasing the acid site strength leads to an increase of dibenzothiophene conversion to the corresponding sulfone. The best results were obtained in the presence of a catalyst, containing a nicotinic acid derivative as cation and phosphomolybdate as anion. The main factors affecting the process consisting of catalyst dosage, temperature, reaction time, oxidant dosage were investigated in detail. Under optimal conditions full oxidation of dibenzothiophene and more than a 90% desulfurization degree of real diesel fuel (initial sulfur content of 2050 ppm) were obtained (the oxidation conditions: NK-1 catalyst, molar ratio H2O2:S 10:1, molar ratio S:Mo 8:1, 1 mL MeCN, 70 °C, 1 h). The synthesized catalysts could be used five times with a slight decrease in activity.


Assuntos
Líquidos Iônicos/química , Oxirredução , Compostos de Tungstênio/química , Catálise , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Líquidos Iônicos/síntese química , Análise Espectral , Enxofre/química
11.
Chem Commun (Camb) ; 56(12): 1867-1870, 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-31950942

RESUMO

Transient nanosheets were fabricated based on the ionic self-assembly of anionic polyoxometalates and cationic peptides appended with azobenzene side chains. The two-dimensional (2D) nanostructures are initiated through ultraviolet (UV) light-actuated trans-to-cis isomerization of azobenzene moieties.


Assuntos
Compostos Azo/química , Nanoestruturas/química , Peptídeos/química , Compostos de Tungstênio/química , Raios Ultravioleta , Ânions/química , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo
12.
Nat Commun ; 11(1): 41, 2020 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900396

RESUMO

The development of programmable microscale materials with cell-like functions, dynamics and collective behaviour is an important milestone in systems chemistry, soft matter bioengineering and synthetic protobiology. Here, polymer/nucleotide coacervate micro-droplets are reconfigured into membrane-bounded polyoxometalate coacervate vesicles (PCVs) in the presence of a bio-inspired Ru-based polyoxometalate catalyst to produce synzyme protocells (Ru4PCVs) with catalase-like activity. We exploit the synthetic protocells for the implementation of multi-compartmentalized cell-like models capable of collective synzyme-mediated buoyancy, parallel catalytic processing in individual horseradish peroxidase-containing Ru4PCVs, and chemical signalling in distributed or encapsulated multi-catalytic protocell communities. Our results highlight a new type of catalytic micro-compartment with multi-functional activity and provide a step towards the development of protocell reaction networks.


Assuntos
Células Artificiais/química , Catalase/química , Rutênio/química , Compostos de Tungstênio/química , Catalase/síntese química , Catálise , Peroxidase do Rábano Silvestre/química
13.
J Photochem Photobiol B ; 204: 111781, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31981989

RESUMO

In the recent years, copper tungstate (CuWO4) has been widely researched for its photocatalytic properties as it responds in the visible light range to augment the utilization of solar energy. In the present report, CuWO4 was synthesized through a facile and cost-effective solvothermal method, followed by annealing process at 700∘C. The structural, morphological, compositional and optical property of the synthesized powders were examined by X-ray diffraction, scanning electron microscope, UV-visible, Raman and photoluminescence studies. The photocatalytic activity of the nanostructured CuWO4 was evaluated by the degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution under one sun light irradiation. The degradation efficiency of MB was found to be about 70% while that of MO was only 57% at 240 min in the same irradiation time. Surprisingly, the degradation process was accelerated by the addition of electron capturing agent H2O2 and thus MB dye was completely degraded within the time interval of 30 min while MO degraded in 75 min. These results prove that CuWO4 nanoparticles possess significant photocatalytic activity towards MO and MB dyes, thus indicating the feasibility of using CuWO4 for the active treatment of organic contaminants in the industrial effluents.


Assuntos
Compostos Azo/química , Peróxido de Hidrogênio/química , Azul de Metileno/química , Luz Solar , Compostos de Tungstênio/química , Catálise , Cobre/química , Nanopartículas/química , Oxirredução , Fotólise/efeitos da radiação
14.
Phys Chem Chem Phys ; 22(5): 2878-2886, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-31950118

RESUMO

Keggin-type polyoxometalate derived ionic liquids (POM-ILs) have recently been presented as effective solvent systems for biomass delignification. To investigate the mechanism of lignin dissolution in POM-ILs, the system involving POM-IL ([C4C1Im]3[PW12O40]) and guaiacyl glycerol-ß-guaiacyl ether (GGE), which contains a ß-O-4 bond (the most dominant bond moiety in lignin), was studied using quantum mechanical calculations and molecular dynamics simulations. These studies show that more stable POM-IL structures are formed when [C4C1Im]+ is anchored in the connecting four terminal oxygen region of the [PW12O40]3- surface. The cations in POM-ILs appear to stabilize the geometry by offering strong and positively charged sites, and the POM anion is a good H-bond acceptor. Calculations of POM-IL interacting with GGE show the POM anion interacts strongly with GGE through many H-bonds and π-π interactions which are the main interactions between the POM-IL anion and GGE and are strong enough to force GGE into highly bent conformations. These simulations provide fundamental models of the dissolution mechanism of lignin by POM-IL, which is promoted by strong interactions of the POM-IL anion with lignin.


Assuntos
Líquidos Iônicos/química , Lignina/química , Simulação de Dinâmica Molecular , Teoria Quântica , Compostos de Tungstênio/química , Guaifenesina/análogos & derivados , Guaifenesina/química , Ligação de Hidrogênio , Lignina/metabolismo , Solubilidade , Eletricidade Estática
15.
Colloids Surf B Biointerfaces ; 188: 110775, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31958619

RESUMO

Combining nanomaterials in varying morphology and functionalities gives rise to a new class of composite materials leading to innovative applications. In this study, we designed a heterostructured hybrid material consisting of two-dimensional bismuth nanosheets augmented by molecularly imprinted networks. Antibiotic overuse is now one of the main concerns in health management, and their monitoring is highly desirable but challenging. So, for this purpose, the resulting composite interface was used as a transducer for quartz crystal microbalances. The main objective was to develop highly selective mass-sensitive sensor for chloramphenicol. Morphological investigation revealed the presence of ultrathin, square shaped nanosheets, 2-3 nm in height and further supplemented by imprinted polymers. Sensor responses are described as the decrease in the frequency of microbalances owing to chloramphenicol re-binding in the templated cavities, yielding a detection limit down to 0.74 µM. This sensor demonstrated a 100 % specific detection of chloramphenicol over its interfering and structural analogs (clindamycin, thiamphenicol, and florfenicol). This composite interface offers the advantage of selective binding and excellent sensitivity due to special heterostructured morphology, in addition to benefits of robustness and online monitoring. The results suggest that such composite-based sensors can be favorable platforms, especially for commercial prospects, to obtain selective detection of other biomolecules of clinical importance.


Assuntos
Materiais Biomiméticos/química , Bismuto/química , Cloranfenicol/análise , Nanoestruturas/química , Polímeros/química , Compostos de Tungstênio/química , Impressão Molecular , Tamanho da Partícula , Técnicas de Microbalança de Cristal de Quartzo , Propriedades de Superfície
16.
Mater Sci Eng C Mater Biol Appl ; 108: 110407, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31923952

RESUMO

Paroxetine is an effective drug for the treatment of depression and stress which has been commonly used in recent years. Because of the widespread use and therapeutic effects of paroxetine, a rapid and sensitive method is needed to determine the trace concentration of paroxetine. Herein, an electrochemical sensor was constructed for the measurement of paroxetine using a modified pencil graphite electrode (PGE). Modification of the PGE was carried out by the reduced graphene oxide/phosphotungstic acid (rGO/PWA) by potentiostatic procedure at -1.2 V for 5 min in phosphate buffer solution with pH = 7.0. Surface morphology analyzing of the modified PGE was performed by scanning electron microscopy (SEM), Raman, XRD, FTIR and electrochemical impedance spectroscopy (EIS) techniques. The kinetic parameter of electron transfer coefficient (α) was calculated for the oxidation process of paroxetine at the modified PGE. Differential pulse voltammetry (DPV) was performed for the determination of PRX. The calibration graph exhibited linear characteristics in the range of 8.0 × 10-9-1.0 × 10-6 M of PRX concentration (R2 = 0.998). The relevant limit of detection was found to be 9.0 × 10-10 M. The modified PGE was successfully performed for the determination of PRX in paroxetine tablets and real samples such as human serum and urine.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Paroxetina/química , Compostos de Tungstênio/química , Técnicas Biossensoriais/métodos , Oxirredução
17.
Talanta ; 210: 120620, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31987167

RESUMO

Boronate affinity is widely used for the isolation of glycoproteins at alkaline conditions. For further proteomic studies, however, it is of highly importance to perform protein adsorption in neutral medium. For this purpose, we report a novel composite material, i.e., 4-carboxyphenylboronic acid (CPBA) functionalized nickel-substituted polyoxometalate [Ni6(en)3(Tris)(H2O)2(PW9O34)]•nH2O (Ni6PW9)-sodium alginate (SA) hybrid. The abundant oxygen atoms in the hybrid (shortly termed as CPBA-Ni6PW9/SA) significantly reduce the pKa value of CPBA moiety, which well facilitates the selective adsorption of glycoproteins at neutral environment (at pH 7.0). The moiety of sodium alginate (SA) in the hybrid further improves the isolation/enrichment capacity for glycoproteins through hydrophilic interaction. The adsorption efficiency of Immunoglobulin G (IgG, 1.0 mL, 100 µg mL-1) by 1.0 mg CPBA-Ni6PW9/SA hybrid reaches up to 91%, and 1.0 mL of Tris-HCl buffer (100 mmol L-1) provides an elution efficiency of 82%. The adsorption behavior of IgG fits Langmuir adsorption model, offering a maximum adsorption capacity of 495 mg g-1. The CPBA-Ni6PW9/SA hybrid is practically applied for the enrichment of glycoproteins from human serum. SDS-PAGE assay result indicates that approximately 92% serum albumin is eliminated and high-purity IgG is obtained. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis clearly demonstrated that after enriching with CPBA-Ni6PW9/SA, 81 glycoproteins are identified and 79.4% recognition selectivity is achieved.


Assuntos
Alginatos/química , Ácidos Borônicos/química , Glicoproteínas/isolamento & purificação , Compostos de Tungstênio/química , Adsorção , Glicoproteínas/sangue , Glicoproteínas/química , Humanos , Estrutura Molecular , Tamanho da Partícula , Propriedades de Superfície
18.
Curr Med Chem ; 27(3): 362-379, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31453779

RESUMO

BACKGROUND: Polyoxometalates (POMs) are negatively charged metal-oxo clusters of early transition metal ions in high oxidation states (e.g., WVI, MoVI, VV). POMs are of interest in the fields of catalysis, electronics, magnetic materials and nanotechnology. Moreover, POMs were shown to exhibit biological activities in vitro and in vivo, such as antitumor, antimicrobial, and antidiabetic. METHODS: The literature search for this peer-reviewed article was performed using PubMed and Scopus databases with the help of appropriate keywords. RESULTS: This review gives a comprehensive overview of recent studies regarding biological activities of polyoxometalates, and their biomedical applications as promising anti-viral, anti-bacterial, anti-tumor, and anti-diabetic agents. Additionally, their putative mechanisms of action and molecular targets are particularly considered. CONCLUSION: Although a wide range of biological activities of Polyoxometalates (POMs) has been reported, they are to the best of our knowledge not close to a clinical trial or a final application in the treatment of diabetes or infectious and malignant diseases. Accordingly, further studies should be directed towards determining the mechanism of POM biological actions, which would enable fine-tuning at the molecular level, and consequently efficient action towards biological targets and as low toxicity as possible. Furthermore, biomedical studies should be performed on solutionstable POMs employing physiological conditions and concentrations.


Assuntos
Compostos de Tungstênio/química , Catálise , Metais , Elementos de Transição
19.
Biosens Bioelectron ; 151: 111973, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31868608

RESUMO

Carbon nitride and WS2 nanocomposite (CN-WS2) with excellent photoelectric activity was prepared by one-step thermal polymerization. By the new strategy of simultaneously loading C and N elements on pure WS2, the formation of CN-WS2 brings high mobility, ultra-fast charge carrier separation and transport, and slows down the recombination rate of electrons and holes. Then, a novel photoelectrochemical biosensor was constructed for 5-formylcytosine detection based on CN-WS2 composite, aldehyde reaction probe (ARP) and ZnFe2O4, where CN-WS2 composite was employed as photoactive material, ARP was used as 5-formylcytosine capture reagent, and ZnFe2O4 was adopted as artificial mimic enzyme. Under the catalysis effect of ZnFe2O4, 4-chloro-1-naphthol was quickly oxidized by H2O2 to produce the insoluble substance of benzo-4-chlorohexadienone, which would be deposited on the electrode surface and caused a decreased PEC response. Under optimal experimental conditions, the biosensor showed low detection limit of 3 pM. This method can also discriminate 5-formylcytosine with other cytosine derivatives. More importantly, the applicability of this method was demonstrated by assessing the effect of antibiotics on the content of 5-formylcytosine in the root, stem and leave of maize seedlings.


Assuntos
Citosina/análogos & derivados , DNA/química , Nanocompostos/química , Nitrilos/química , Plântula/química , Compostos de Tungstênio/química , Zea mays/química , Ligas/química , Técnicas Biossensoriais , Citosina/análise , Técnicas Eletroquímicas , Eletrodos , Peróxido de Hidrogênio/química , Ferro/química , Limite de Detecção , Naftóis/química , Óxidos/química , Processos Fotoquímicos , Propriedades de Superfície , Zinco/química
20.
Colloids Surf B Biointerfaces ; 185: 110600, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31704608

RESUMO

In this communication, fenugreek ß-amylase was immobilized onto functionalized tungsten disulfide nanoparticles through cross-linker glutaraldehyde and successful immobilization was confirmed by SEM, AFM and FTIR spectroscopy. To make the process economical and efficient, optimization of independent variables was carried out using Box-Behnken design of response surface methodology. Approximately similar predicted (85.6%) and experimental (84.2%) immobilization efficiency revealed that the model is suitable for design of space. Optimum temperature was calculated to be 60 °C. After immobilization, an increased Km (2.12 times) and a decreased Vmax (0.58 times), indicated inaccessibility of active site residues to the substrate. The immobilized enzyme retained 77% relative activity after 10 uses whereas 40% residual activity was obtained after 120 days. An increased half-life with concomitantly decreased kinetic rate constant revealed that the immobilized enzyme is more stable at a higher temperature and the process followed first-order kinetics (R2 > 0.93). The limit of detection for maltose and sucrose fluorescence biosensor was found to be 0.052 and 0.096 mM, respectively. Thermodynamic parameters such as changes in Gibbs free energy (ΔG < 0), enthalpy (ΔH > 0) and entropy (ΔS >0) revealed that the process is spontaneous and endothermic, driven by hydrophobic interactions. Thermo-stability data at higher temperature for the immobilized enzyme makes it a suitable candidate for industrial applications in the production of maltose in food and pharmaceutical industries. Furthermore, fluorescence biosensor could be used to detect and quantify maltose and sucrose to maintain the quality of industrial products.


Assuntos
Dissulfetos/química , Enzimas Imobilizadas/metabolismo , Maltose/metabolismo , Nanopartículas/química , Sacarose/metabolismo , Trigonella/enzimologia , Compostos de Tungstênio/química , beta-Amilase/metabolismo , Estabilidade Enzimática , Enzimas Imobilizadas/química , Concentração de Íons de Hidrogênio , Cinética , Maltose/química , Sacarose/química , Temperatura , Termodinâmica , beta-Amilase/química
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