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1.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2737-2745, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418199

RESUMO

To investigate the changes of Zn availability and transformation in calcareous soil, orga-nic materials (maize straw, biofertilizer, fulvic acids, and chicken manure) were thoroughly mixed with the soils amended with Zn fertilizer in the nylon net bags and buried in a field. Results showed that compared with control (neither Zn nor organic materials), Zn fertilizer alone and combined addition with organic materials significantly increased soil total Zn concentration (7.2%-13.8%) and DTPA-Zn concentration (2.1-2.8 folds). For the Zn amended treatments, the contributions of organic amendments to soil total Zn and DTPA-Zn concentration decreased in the order of chicken manure > biofertilizer > maize straw > fulvic acids. The highest conversion rate of exogenous Zn into DTPA-Zn occurred in the treatments with straw and biofertilizer. In comparison with single Zn application, combination of Zn fertilizer with organic materials increased soil organic matter and stimulated more Zn weakly bound to organic matter, enhanced mobility factor and reduced distribution index of Zn in soil. The differences in soil Zn availability and transformation among the combinations of Zn fertilizer and organic materials were likely linked to the inherent properties of organic materials such as maturity degree and Zn content. Considering the environment safety and cost reduction, combining Zn fertilizer and straw return was the best practice to enhance Zn availability in the Zn-deficient calcareous soil, although its contribution to Zn availability was less than the combination of biofertilizer or chicken manure with Zn fertilizer.


Assuntos
Fertilizantes , Poluentes do Solo , Zinco/química , Esterco , Solo/química
2.
Bioresour Technol ; 291: 121868, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31357045

RESUMO

To clarify the adsorption behaviors of typical heavy metals onto sludge extracellular polymeric substances (EPS), the adsorption capacities and mechanisms, as well as the contributions of the different EPS components (proteins, humic acids and polysaccharides), to the adsorption of Zn2+, Cu2+ and Cd2+ were separately explored. Overall, proteins exhibited a relatively high adsorption capacity for the three metals ions, followed by humic acid, whereas least for polysaccharides. The adsorption of Cu2+ and Cd2+ onto proteins, humic acid and polysaccharides fit well to the Freundlich isotherm, whereas Langmuir model was the best fit for Zn2+ bindings onto polysaccharides/humic acid. The binding of Cu2+, Zn2+ and Cd2+ onto the three EPS components was exothermically favorable, and significant electrostatic interactions were observed for the heavy metals sorption onto humic acid and proteins. In addition, the effect of metal ions sorption on the spectrum of the proteins, polysaccharides and humic acid was also explored.


Assuntos
Cádmio/química , Cobre/química , Substâncias Húmicas , Polissacarídeos/química , Proteínas/metabolismo , Esgotos , Zinco/química , Adsorção , Cádmio/metabolismo , Cobre/metabolismo , Proteínas/química , Esgotos/química , Zinco/metabolismo
3.
Chem Commun (Camb) ; 55(60): 8880-8883, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31321399

RESUMO

We developed an artificial hydrolase based on the symmetrical Pizza6 ß-propeller protein for the metal-free hydrolysis of 4-nitrophenyl acetate and butyrate. Through site-specific mutagenesis and crystallisation studies, the catalytic mechanism was investigated and found to be dependent on a threonine-histidine dyad. The mutant with additional histidine residues generated the highest kcat values, forming a His-His-Thr triad and matched previously reported metalloenzymes. The highly symmetrical ß-propeller artificial enzymes and their protein-metal complexes have potential to be utilised in bioinorganic and supramolecular chemistry, as well as being developed further into 2D/3D catalytic materials.


Assuntos
Hidrolases/química , Sequência de Aminoácidos , Ácido Aspártico/química , Ácido Aspártico/genética , Butiratos/química , Catálise , Cobre/química , Histidina/química , Histidina/genética , Hidrolases/genética , Hidrólise , Cinética , Mutagênese Sítio-Dirigida , Nitrofenóis/química , Engenharia de Proteínas/métodos , Estrutura Terciária de Proteína , Treonina/química , Zinco/química
4.
Chemosphere ; 233: 524-531, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31185336

RESUMO

Metal-organic frameworks (MOFs) addition into membranes is able to improve water flux without jeopardizing selectivity, which enhance the performance of reverse osmosis (RO) processes owing to its intrinsic physical and chemical properties, such as porosity structure and high compatibility with the polymer matrix. However, there were few studies about influences of nanoparticle size on MOFs-incorporated thin film nanocomposite (TFN) membranes. Here ZIF-8 particles with different average sizes (50, 150 and 400 nm) were synthesized and incorporated into organic monomer solution to fabricate TFN membranes for water desalination to investigate the membrane performance changed by nanomaterial size. Dispersion of ZIF-8 in selective layer during interfacial polymerization process was affected by particle size. The apparent morphology, roughness, and hydrophilicity of ZIF-8 modified TFN membranes were changed subsequently, which affected the water permeability, salt rejection and fouling resistance performance of the TFN membranes correspondingly. Our results showed that the TFN membrane comprising ZIF-8 with particle size of 50 nm had the best performance due to the highest dispersion in polyamide layer, revealing the importance of MOFs particle size in further investigation of MOFs-incorporated TFN membranes.


Assuntos
Filtração/métodos , Membranas Artificiais , Estruturas Metalorgânicas/química , Nanopartículas/química , Nylons/química , Purificação da Água/métodos , Zinco/química , Interações Hidrofóbicas e Hidrofílicas , Nanocompostos/química , Osmose , Tamanho da Partícula , Permeabilidade , Porosidade , Propriedades de Superfície
5.
Chem Commun (Camb) ; 55(54): 7852-7855, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31215553
6.
J Agric Food Chem ; 67(25): 6995-7004, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31194541

RESUMO

Food-borne nanoparticles (FNs) may be used as nanocarriers for metal ion chelation in micronutrient supplements. In this paper, the preparation and characterization of hydrophilic FNs were reported from beef broth cooked with a pressure cooker at 117 °C for different periods (30, 50, and 70 min) and their potential application as nanocarriers for zinc was investigated. The broth FNs are quasi-spherical with good water solubility and ultrasmall size, which can emit a strong sapphire color under 365 nm ultraviolet irradiation. X-ray photoelectron spectroscopy (XPS) analysis showed that there are carboxyl, amino, and hydroxyl groups on the FNs, which are useful for Zn(II) chelation. The vibration band of C═O at 1688 cm-1 in the infrared spectrum of FNs shifted to 1718 cm-1 after binding with Zn(II) ions, suggesting the participation of the carbonyl group in Zn(II) ion chelation. The appearance of Zn2p XPS peaks, at 1021.6 and 1045 eV for Zn(II)-FNs, clearly demonstrated the formation of Zn-O between the FNs and zinc ions. Biodistribution of FNs and the Zn(II)-FN complex in normal rat kidney cells demonstrated that they could easily enter normal rat kidney cells. A downfield was found for the signals of Zn(II)-FNs in 1H nuclear magnetic resonance spectroscopy and strongly suggested the binding of Zn(II) ions to FNs through carboxylic acid, hydroxyl, and amine groups. In addition, no obvious cytotoxicity was found for Zn(II)-FNs compared to zinc (ZnSO4) and commercial zinc gluconate. The results revealed that the FNs from beef broth may have a potential as nanocarriers for zinc chelation.


Assuntos
Portadores de Fármacos/química , Produtos da Carne/análise , Nanopartículas/química , Zinco/química , Animais , Bovinos , Linhagem Celular , Quelantes/química , Composição de Medicamentos , Interações Hidrofóbicas e Hidrofílicas , Ratos , Solubilidade , Distribuição Tecidual
7.
Int J Nanomedicine ; 14: 3471-3490, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31190805

RESUMO

Background: Zinc-doped hydroxyapatite has been proposed as a graft biomaterial for bone regeneration. However, the effect of zinc on osteoconductivity is still controversial, since the release and resorption of calcium, phosphorus, and zinc in graft-implanted defects have rarely been studied. Methods: Microspheres containing alginate and either non-doped carbonated hydroxyapatite (cHA) or nanocrystalline 3.2 wt% zinc-doped cHA (Zn-cHA) were implanted in critical-sized calvarial defects in Wistar rats for 1, 3, and 6 months. Histological and histomorphometric analyses were performed to evaluate the volume density of newly formed bone, residual biomaterial, and connective tissue formation. Biomaterial degradation was characterized by transmission electron microscopy (TEM) and synchrotron radiation-based X-ray microfluorescence (SR-µXRF), which enabled the elemental mapping of calcium, phosphorus, and zinc on the microsphere-implanted defects at 6 months post-implantation. Results: The bone repair was limited to regions close to the preexistent bone, whereas connective tissue occupied the major part of the defect. Moreover, no significant difference in the amount of new bone formed was found between the two microsphere groups. TEM analysis revealed the degradation of the outer microsphere surface with detachment of the nanoparticle aggregates. According to SR-µXRF, both types of microspheres released high amounts of calcium, phosphorus, and zinc, distributed throughout the defective region. The cHA microsphere surface strongly adsorbed the zinc from organic constituents of the biological fluid, and phosphorus was resorbed more quickly than calcium. In the Zn-cHA group, zinc and calcium had similar release profiles, indicating a stoichiometric dissolution of these elements and non-preferential zinc resorption. Conclusions: The nanometric size of cHA and Zn-cHA was a decisive factor in accelerating the in vivo availability of calcium and zinc. The high calcium and zinc accumulation in the defect, which was not cleared by the biological medium, played a critical role in inhibiting osteoconduction and thus impairing bone repair.


Assuntos
Alginatos/química , Regeneração Óssea , Cálcio/metabolismo , Durapatita/química , Microesferas , Nanopartículas/química , Zinco/química , Zinco/metabolismo , Animais , Materiais Biocompatíveis/química , Disponibilidade Biológica , Regeneração Óssea/efeitos dos fármacos , Carbonatos/química , Morte Celular , Linhagem Celular , Sobrevivência Celular , Feminino , Camundongos , Nanopartículas/ultraestrutura , Ratos Wistar , Crânio/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
8.
Bioelectrochemistry ; 129: 106-115, 2019 Oct.
Artigo em Espanhol | MEDLINE | ID: mdl-31153125

RESUMO

Due to their desirable elastic modulus and density that are similar to natural bone, non-toxic element containing magnesium alloys are regarded as promising bio-degradable materials. A biodegradable HA-particle-reinforced magnesium-matrix composite Mg-3Zn-0.2Ca-1HA (wt%) was fabricated for biomedical application by a combination of high shear solidification (HSS) and hot extrusion technology. The microstructure, mechanical properties, corrosion resistance and cell biocompatibility of the composite were subsequently investigated. In comparison with the matrix alloy, the as-cast Mg-3Zn-0.2Ca-1HA composite obtained by HSS technology exhibited a uniform and fine grained structure, further refined after a hot extrusion ratio of 36:1. The yield strength (0.2%YS), ultimate tensile strength and elongation of the extruded composite were 322 MPa, 341 MPa and 7.6%, respectively. The corrosion rate of the as-extruded Mg-3Zn-0.2Ca-1HA composite was measured to be 1.52 mm/y. Electrochemical and immersion tests showed that the corrosion resistance of the composite is slightly improved comparing to that of the matrix alloy.


Assuntos
Ligas/química , Materiais Biocompatíveis/química , Durapatita/química , Magnésio/química , Zinco/química , Animais , Linhagem Celular , Corrosão , Fibroblastos/citologia , Teste de Materiais , Camundongos , Resistência à Tração
9.
Inorg Chem ; 58(16): 10501-10507, 2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31247870

RESUMO

Zinc thiolate bonds are intriguing targets of study because of their redox noninnocence and prevalence in bioinorganic sites. A five-coordinate zinc dithiolate complex [Et4N]2[LZn] (H4L = N,N'-di(2-sulfhydrylphenyl)-pyridine-2,6-dicarboxamide) was synthesized to study the oxidative reactivity of zinc thiolate bonds. Multiple chemically reversible reactions of the zinc thiolate bonds were identified. Oxidation of [Et4N]2[LZn] with iodine resulted in structural rearrangement to a bimetallic disulfide-bridged complex. In contrast, the addition of elemental sulfur to [Et4N]2[LZn] resulted in the insertion of a neutral S3 fragment into the Zn-thiolate bond to selectively form an unusual monometallic tetrasulfanido complex. When oxidized, this tetrasulfanido compound rearranged to form a bimetallic trisulfide-bridged complex. The observed diversity of zinc thiolate reactivity, particularly with sulfur, is likely important in biological contexts.


Assuntos
Complexos de Coordenação/química , Compostos de Sulfidrila/química , Sulfetos/química , Enxofre/química , Zinco/química , Modelos Moleculares , Estrutura Molecular , Oxirredução
10.
Talanta ; 201: 286-294, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122425

RESUMO

Herein, high performance peroxidase-like activity of zinc and cobalt bi-metal metal-organic framework (ZnCo MOF) is reported and applied for the sensitive measurement of atropine. ZnCo MOF was synthesized by the reaction of 2-methylimidazole with Zn and Co (II) cations in aqueous media. The colorimetric and fluorometric experiments were applied to investigate the catalytic activity of obtained MOF, using o-phenylenediamine (OPD) and terephthalic acid (TA) peroxidase substrates, respectively. The results demonstrated the more efficient mimetic behavior of ZnCo MOF compared with common Zn or Co MOFs. Besides, it was found that atropine hindered the catalytic action of ZnCo MOF and this effect was intensified by increasing the atropine concentration. So, it was considered to design a sensitive analytical assay for atropine detection. To assure a high specific recognition, molecularly imprinted polymer (MIP)-based extraction using magnetic graphene oxide supports was applied to extract atropine before its determination. The combination between the high specific extraction and great catalytic activity of ZnCo MOF led to the ultrasensitive and reliable determination of atropine. The best linear range of calibration graph was achieved using fluorometric detection system for 0.1-45 ng mL-1 atropine concentrations, and detection limit (3Sb/m) was 27 pg mL-1. The relative standard deviations (RSD %) for the determination of 1, and 10 ng mL-1 atropine (n = 5) were 2.13% and 3.08%, respectively. The explained fluorometric assay was examined for the measurement of atropine in biological fluids (Recoveries were in the range of 95.90-103.57%), and the results were validated by an official method.


Assuntos
Atropina/sangue , Colorimetria/métodos , Grafite/química , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Espectrometria de Fluorescência/métodos , Adulto , Materiais Biomiméticos/síntese química , Materiais Biomiméticos/química , Cobalto/química , Humanos , Limite de Detecção , Fenômenos Magnéticos , Masculino , Estruturas Metalorgânicas/síntese química , Pessoa de Meia-Idade , Impressão Molecular , Peroxidase/química , Porosidade , Zinco/química
11.
J Phys Chem Lett ; 10(10): 2585-2592, 2019 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-31039606

RESUMO

Identifying the zinc (Zn) ligation and coordination environment in complex biological and environmental systems is crucial to understand the role of Zn as a biologically essential but sometimes toxic metal. Most studies on Zn coordination in biological or environmental samples rely on the extended X-ray absorption fine structure (EXAFS) region of a Zn K-edge X-ray absorption spectroscopy (XAS) spectrum. However, EXAFS analysis cannot identify unique nearest neighbors with similar atomic number (i.e., O versus N) and provides little information on Zn ligation. Herein, we demonstrate that high energy resolution-X-ray absorption near edge structure (HR-XANES) spectroscopy enables the direct determination of Zn ligation in whole cell bacteria, providing additional insights lost from EXAFS analysis at a fraction of the scan time and Zn concentration. HR-XANES is a relatively new technique that has improved our understanding of trace metals (e.g., Hg, Cu, and Ce) in dilute systems. This study is the first to show that HR-XANES can unambiguously detect Zn coordination to carboxyl, phosphoryl, imidazole, and/or thiol moieties in model microorganisms.


Assuntos
Bacillus subtilis/química , Pseudomonas putida/química , Zinco/química , Bacillus subtilis/citologia , Pseudomonas putida/citologia , Espectroscopia por Absorção de Raios X
12.
Water Sci Technol ; 79(6): 1029-1041, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31070583

RESUMO

In the present work, the performance of spent coffee grounds (SCG) as an adsorbent in the treatment of real soil washing wastewater (SWW) was evaluated. Scanning electron microscopy, Fourier transform infrared spectroscopy, zeta potential measurement and Brunauer-Emmett-Teller analysis were utilized to determine the physicochemical characteristics of SCG. Maximum removal efficiency of 68.73% for Cu(II), 57.23% for Pb(II) and 84.55% for Zn(II) was attained at 2.5 g SCG, 300 min and 328 K. Error analysis was performed using root mean square error (RMSE) and sum of square error (SSE). Equilibrium data correlated well with the Langmuir isotherm for Pb(II) adsorption and Freundlich model for the removal of Cu(II) and Zn(II). The kinetic study shows that adsorption of the heavy metals using SCG can be satisfactorily described using the pseudo-second order equation (R2 ≥ 0.9901; RMSE ≤ 15.0539; SSE ≤ 145.1461). Activation parameters including activation energy, change in free energy of activation, activation entropy change (ΔS*) and activation enthalpy change (ΔH*) were determined using Arrhenius and Eyring equations. Thermodynamic studies show that adsorption of the heavy metals using SCG is spontaneous, endothermic (ΔH° ≥ 9.80 kJ/mol·K) and results in increased randomness at the solid/solution interface (ΔS° ≥ 2.28 J/mol).


Assuntos
Metais Pesados/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Café/química , Cobre/análise , Cobre/química , Recuperação e Remediação Ambiental , Concentração de Íons de Hidrogênio , Cinética , Chumbo/química , Metais Pesados/análise , Solo/química , Termodinâmica , Águas Residuárias/química , Poluentes Químicos da Água/análise , Zinco/química
13.
Water Sci Technol ; 79(7): 1297-1308, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31123229

RESUMO

The presence of heavy metals in the environment has increased, and cadmium (Cd) and zinc (Zn) are considered to be among the most dangerous. An upflow Al-electrocoagulation reactor was used to remove Cd2+ and Zn2+ ions from aqueous media. The system consisted of perforated aluminum circular electrodes for fluid distribution with elimination of external agitation. The effect of different parameters, i.e. current intensity, electrolysis time, concentration of Cd2+ and Zn2+ ions and electrolytic support dose were optimized by response surface methodology. The results indicated that increasing the current intensity and the electrolysis time had a positive effect on the elimination efficiency of the pollutant ions. Likewise, increasing the dose of electrolytic support and decreasing the concentration of the pollutants improved the efficiency of the system. The optimal results were: current intensity of 0.4 A, electrolysis time of 40 min, ion concentration of 44.6 mg·L-1 and electrolytic support dose of 0.56 mg·L-1, with the maximum elimination percentages of 96 ± 3.8% and 96 ± 2.7% for Cd2+ and Zn2+, respectively. This study showed that the electrocoagulation process in an upflow electrocoagulation reactor could be successfully applied to remove pollutants from water.


Assuntos
Reatores Biológicos , Metais Pesados/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Alumínio/química , Cádmio/análise , Cádmio/química , Eletrocoagulação , Eletrodos , Eletrólise , Concentração de Íons de Hidrogênio , Metais Pesados/análise , Poluentes Químicos da Água/análise , Zinco/análise , Zinco/química
14.
Sensors (Basel) ; 19(9)2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-31052519

RESUMO

A small extent of endogenous labile zinc is involved in many vital physiological roles in living systems. However, its detailed functions have not been fully elucidated. In this study, we developed a novel biheteroaryl-based low molecular weight fluorescent sensor, 3-(phenylsulfonyl)-pyrazine-pyridone (5b), and applied it for the detection of endogenous labile zinc ions from lung cancer cells during apoptosis. The electron-withdrawing property of the sulfonyl group between the phenyl ring as an electron donor and the pyridone ring as a fluorophore inhibited the intramolecular charge transfer state, and the background fluorescence of the sensor was decreased in aqueous media. From the structure-fluorescence relationship analysis of the substituent effects with/without Zn2+, compound 5b acting as a sensor possessed favorable properties, including a longer emission wavelength, a large Stokes shift (over 100 nm), a large fluorescence enhancement in response to Zn2+ under physical conditions, and good cell membrane permeability in living cells. Fluorescence imaging studies of human lung adenocarcinoma cells (A549) undergoing apoptosis revealed that compound 5b could detect endogenous labile zinc ions. These experiments suggested that the low molecular weight compound 5b is a potential fluorescence sensor for Zn2+ toward understanding its functions in living systems.


Assuntos
Técnicas Biossensoriais , Íons/isolamento & purificação , Neoplasias Pulmonares/química , Zinco/isolamento & purificação , Humanos , Íons/química , Neoplasias Pulmonares/diagnóstico , Imagem Óptica , Pirazinas/síntese química , Pirazinas/química , Piridonas/síntese química , Piridonas/química , Água/química , Zinco/química
15.
Anal Bioanal Chem ; 411(19): 4673-4682, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31098744

RESUMO

Bile acids (BAs) play an integral role in digestion through the absorption of nutrients, emulsification of fats and fat-soluble vitamins, and maintenance of cholesterol levels. Metabolic disruption, diabetes, colorectal cancer, and numerous other diseases have been linked with BA disruption, making improved BA analyses essential. To date, most BA measurements are performed using liquid chromatography separations in conjunction with mass spectrometry measurements (LC-MS). However, 10-40 min LC gradients are often used for BA analyses and these may not even be sufficient for distinguishing all the important isomers present in the human body. Ion mobility spectrometry (IMS) is a promising tool for BA evaluations due to its ability to quickly separate isomeric molecules with subtle structural differences. In this study, we utilized drift tube IMS (DTIMS) coupled with MS to characterize 56 different unlabeled BA standards and 16 deuterated versions. In the DTIMS-MS analyses of 12 isomer groups, BAs with smaller m/z values were easily separated in either their deprotonated or sodiated forms (or both). However, as the BAs grew in m/z value, they became more difficult to separate with two isomer groups being inseparable. Metal ions such as copper and zinc were then added to the overlapping BAs, and due to different binding sites, the resulting complexes were separable. Thus, the rapid structural measurements possible with DTIMS-MS show great potential for BAs measurements with and without prior LC separations.


Assuntos
Ácidos e Sais Biliares/química , Espectrometria de Mobilidade Iônica/métodos , Ácidos e Sais Biliares/normas , Cobre/química , Humanos , Isomerismo , Estrutura Molecular , Padrões de Referência , Zinco/química
16.
Chemistry ; 25(42): 9967-9972, 2019 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-31056773

RESUMO

3,3'-Diformyl-1,1'-bi-2-naphthol or its methoxymethyl-protected derivative is found to undergo a highly selective reaction with excess bromine in CH2 Cl2 at reflux to give the novel 5,5',6,6'-tetrabrominated product (S)- or (R)-2. The observed electrophilic substitution at the 5,5'-positons of an optically active binaphthyl compound is unprecedented. Unlike unbrominated 3,3'-diformyl-1,1'-bi-2-naphthol, which is not suitable for fluorescent recognition in water, compound (S)-2, in combination with Zn2+ , exhibits a highly enantioselective fluorescent response toward amino acids in aqueous solution (HEPES buffer, pH 7.4). It is further found that the condensation product of (R)-2 with tryptophan, (R)-3, shows dual-responsive emissions toward amino acids; the short wavelength (λ1 =350 nm) emission is sensitive to the concentration of the substrate regardless of the chiral configuration and the long wavelength (λ2 >500 nm) emission is highly enantioselective. Thus, the use of (R)-3 allows the simultaneous determination of the concentration and enantiomeric composition of an amino acid sample from one fluorescence measurement.


Assuntos
Aldeídos/química , Aminoácidos/análise , Corantes Fluorescentes/química , Naftalenos/química , Cátions Bivalentes , Conformação Molecular , Estereoisomerismo , Água , Zinco/química
17.
Environ Sci Pollut Res Int ; 26(18): 18343-18353, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31044376

RESUMO

ZnAl-layered double hydroxide-loaded banana straw biochar (ZnAl-LDH-BSB) was prepared via the hydrothermal method, and the efficient phosphorus removal agent ZnAl-LDO-BSB was obtained by calcination at 500 °C. Based on the ZnAl-LDO-BSB adsorption characteristics, the adsorption mechanism was evaluated via TG/DTA, FTIR, XRD, SEM, HRTEM, and other characterization methods. The results showed that the ZnAl-LDO-BSB assembled into microspheres with typical hexagonal lamellar structures and presented good thermal stability. The adsorption of total phosphate (TP) by ZnAl-LDO-BSB conforms to the Langmuir model, and the theoretical maximum adsorption capacity is 185.19 mg g-1. The adsorption kinetics were in accordance with the second-order kinetic model, and the anion influence on TP adsorption followed the order CO32- > SO42- > NO3-. The combination of zeta potential measurements with the FTIR, XRD, SEM, HRTEM, and XPS results suggested that ZnAl-LDO-BSB adsorbs TP mainly by electrostatic adsorption, surface coordination, and anion intercalation. Graphical abstract.


Assuntos
Alumínio/química , Carvão Vegetal , Musa , Fosfatos/química , Águas Residuárias/química , Purificação da Água/métodos , Zinco/química , Adsorção , Hidróxidos/química , Cinética , Fosfatos/isolamento & purificação
18.
Artigo em Inglês | MEDLINE | ID: mdl-31046561

RESUMO

Acetaminophen, a popular NSAID (Non-steroidal anti-inflammatory drug), was studied for efficacy of removal from aqueous solutions. While Octolig® (a polyethylenediimine covalently attached to silica gel) is able to remove many simple anions and some acidic pharmaceuticals having a pKa value less than 4.5, it lacked efficacy with acetaminophen. Accordingly different transition- metal derivatives of Octolig® were tested by column chromatography using as substrates Octolig® derivatives of copper(II), cobalt(II), iron(III), manganese(II), nickel(II), and zinc(II).


Assuntos
Anti-Inflamatórios não Esteroides/isolamento & purificação , Sílica Gel/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Água/química , Acetaminofen/isolamento & purificação , Acetaminofen/farmacocinética , Ânions , Anti-Inflamatórios não Esteroides/farmacocinética , Cromatografia/métodos , Cobalto/química , Cobre/química , Compostos Férricos/química , Humanos , Manganês/química , Níquel/química , Polietilenos/química , Sílica Gel/metabolismo , Soluções/química , Poluentes Químicos da Água/farmacocinética , Zinco/química
19.
Acta Crystallogr D Struct Biol ; 75(Pt 5): 475-487, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31063150

RESUMO

Phosphomannose isomerase (PMI) is a housekeeping enzyme that is found in organisms ranging from bacteria to fungi to mammals and is important for cell-wall synthesis, viability and signalling. PMI is a zinc-dependent enzyme that catalyses the reversible isomerization between mannose 6-phosphate (M6P) and fructose 6-phosphate (F6P), presumably via the formation of a cis-enediol intermediate. The reaction is hypothesized to involve ring opening of M6P, the transfer of a proton from the C2 atom to the C1 atom and between the O1 and O2 atoms of the substrate, followed by ring closure resulting in the product F6P. Several attempts have been made to decipher the role of zinc ions and various residues in the catalytic function of PMI. However, there is no consensus on the catalytic base and the mechanism of the reaction catalyzed by the enzyme. In the present study, based on the structure of PMI from Salmonella typhimurium, site-directed mutagenesis targeting residues close to the bound metal ion and activity studies on the mutants, zinc ions were shown to be crucial for substrate binding. These studies also suggest Lys86 as the most probable catalytic base abstracting the proton in the isomerization reaction. Plausible roles for the highly conserved residues Lys132 and Arg274 could also be discerned based on comparison of the crystal structures of wild-type and mutant PMIs. PMIs from prokaryotes possess a low sequence identity to the human enzyme, ranging between 30% and 40%. Since PMI is important for the virulence of many pathogenic organisms, the identification of catalytically important residues will facilitate its use as a potential antimicrobial drug target.


Assuntos
Aminoácidos/metabolismo , Frutosefosfatos/metabolismo , Manose-6-Fosfato Isomerase/química , Manose-6-Fosfato Isomerase/metabolismo , Manosefosfatos/metabolismo , Salmonella typhimurium/enzimologia , Zinco/metabolismo , Aminoácidos/química , Aminoácidos/genética , Catálise , Domínio Catalítico , Cristalografia por Raios X , Isomerismo , Manose-6-Fosfato Isomerase/genética , Modelos Moleculares , Mutagênese Sítio-Dirigida , Mutação , Conformação Proteica , Especificidade por Substrato , Zinco/química
20.
Int J Mol Sci ; 20(9)2019 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-31058825

RESUMO

Mg-based alloys have great potential for development into fixation implants because of their highly biocompatible and biodegradable metallic properties. In this study, we sought to determine the biocompatibility of Mg60Zn35Ca5 bulk metallic glass composite (BMGC) with fabricated implants in a rabbit tendon-bone interference fixation model. We investigated the cellular cytotoxicity of Mg60Zn35Ca5 BMGC toward rabbit osteoblasts and compared it with conventional titanium alloy (Ti6Al4V) and polylactic acid (PLA). The results show that Mg60Zn35Ca5 BMGC may be classed as slightly toxic on the basis of the standard ISO 10993-5. We further characterized the osteogenic effect of the Mg60Zn35Ca5 BMGC extraction medium on rabbit osteoblasts by quantifying extracellular calcium and mineral deposition, as well as cellular alkaline phosphatase activity. The results of these tests were found to be promising. The chemotactic effect of the Mg60Zn35Ca5 BMGC extraction medium on rabbit osteoblasts was demonstrated through a transwell migration assay. For the in vivo section of this study, a rabbit tendon-bone interference fixation model was established to determine the biocompatibility and osteogenic potential of Mg60Zn35Ca5 BMGC in a created bony tunnel for a period of up to 24 weeks. The results show that Mg60Zn35Ca5 BMGC induced considerable new bone formation at the implant site in comparison with conventional titanium alloy after 24 weeks of implantation. In conclusion, this study revealed that Mg60Zn35Ca5 BMGC demonstrated adequate biocompatibility and exhibited significant osteogenic potential both in vitro and in vivo. These advantages may be clinically beneficial to the development of Mg60Zn35Ca5 BMGC implants for future applications.


Assuntos
Materiais Biocompatíveis/química , Cálcio/química , Vidro/química , Magnésio/química , Nanopartículas Metálicas/química , Osteogênese/efeitos dos fármacos , Zinco/química , Animais , Materiais Biocompatíveis/farmacologia , Biomarcadores , Osso e Ossos/diagnóstico por imagem , Osso e Ossos/metabolismo , Movimento Celular , Sobrevivência Celular/efeitos dos fármacos , Matriz Extracelular/metabolismo , Imagem Tridimensional , Teste de Materiais , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Coelhos , Tendões , Microtomografia por Raio-X
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