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1.
Chemosphere ; 258: 127288, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32947659

RESUMO

The discharge of toxic elements from tailings soils in the aquatic environments occurs chiefly in the presence of indigenous bacteria. The biotic components may interact in the opposite direction, leading to the formation of a passivation layer, which can inhibit the solubility of the elements. In this work, the influence of jarosite on the bio-immobilization of toxic elements was studied by native bacteria. In batch experiments, the bio-immobilization of heavy metals by an inhibitory layer was examined in the different aquatic media using pure cultures of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A variety of analyses also investigated the mechanisms of metals bio-immobilization. Among different tests, the highest metal solubility yielded 99% Mn, 91% Cr, 95% Fe, and 78% Cu using A. ferrooxidans in 9KFe medium after ten days. After 22 days, these percentages decreased down to 30% Mn and about 20% Cr, Fe, and Cu, likely due to metal immobilization by biogenic jarosite. The formation of jarosite was confirmed by an electron probe micro-analyzer (EPMA), X-ray diffraction (XRD), and scanning electron microscope (SEM). The mechanisms of metal bio-immobilization by biogenic jarosite from tailings soil confirmed three main steps: 1) the dissolution of metal sulfides in the presence of Acidithiobacillus bacteria; 2) the nucleation of jarosite on the surface of sulfide minerals; 3) the co-precipitation of dissolved elements with jarosite during the bio-immobilization process, demonstrated by a structural study for jarosite. Covering the surface of soils by the jarosite provided a stable compound in the acidic environment of mine-waste.


Assuntos
Compostos Férricos/química , Substâncias Perigosas/análise , Sulfatos/química , Acidithiobacillus , Acidithiobacillus thiooxidans , Bactérias , Substâncias Perigosas/toxicidade , Metais Pesados , Minerais , Solubilidade , Sulfetos/química , Difração de Raios X
2.
Nat Commun ; 11(1): 4170, 2020 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-32820174

RESUMO

Sulfur-sulfur motifs widely occur in vital function and drug design, which yearns for polysulfide construction in an efficient manner. However, it is a great challenge to install desired functional groups on both sides of sulfur-sulfur bonds at liberty. Herein, we designed a mesocyclic bilateral disulfurating reagent for sequential assembly and modular installation of polysulfides. Based on S-O bond dissociation energy imparity (mesocyclic compared to linear imparity is at least 5.34 kcal mol-1 higher), diverse types of functional molecules can be bridged via sulfur-sulfur bonds distinctly. With these stable reagents, excellent reactivities with nucleophiles including C, N and S are comprehensively demonstrated, sequentially installing on both sides of sulfur-sulfur motif with various substituents to afford six species of unsymmetrical polysulfides including di-, tri- and even tetra-sulfides. Life-related molecules, natural products and pharmaceuticals can be successively cross-linked with sulfur-sulfur bond. Remarkably, the cyclization of tri- and tetra-peptides affords 15- and 18-membered cyclic disulfide peptides with this reagent, respectively.


Assuntos
Dissulfetos/química , Indicadores e Reagentes/química , Peptídeos/química , Sulfetos/química , Enxofre/química , Produtos Biológicos/química , Técnicas de Química Sintética/métodos , Ciclização , Indicadores e Reagentes/síntese química , Modelos Químicos , Estrutura Molecular , Oxirredução , Preparações Farmacêuticas/química
3.
Chemosphere ; 260: 127574, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32688316

RESUMO

Artisanal and small-scale gold mining (ASGM) operations are major contributors to the Philippines' annual gold (Au) output (at least 60%). Unfortunately, these ASGM activities lacked adequate tailings management strategies, so contamination of the environment is prevalent. In this study, soil contamination with copper (Cu), lead (Pb), zinc (Zn) and arsenic (As) due to ASGM activities in Nabunturan, Davao de Oro, Philippines was investigated. The results showed that ASGM-impacted soils had Cu, Pb, Zn and As up to 3.6, 83, 73 and 68 times higher than background levels, respectively and were classified as 'extremely' polluted (CD = 30-228; PLI = 5.5-34.8). Minerals typically found in porphyry copper-gold ores like pyrite, chalcopyrite, malachite, galena, sphalerite and goethite were identified by XRD and SEM-EDS analyses. Furthermore, sequential extraction results indicate substantial Cu (up to 90%), Pb (up to 50%), Zn (up to 65%) and As (up to 48%) partitioned with strongly adsorbed, weak acid soluble, reducible and oxidisable fractions, which are considered as 'geochemically mobile' phases in the environment. Although very high Pb and Zn were found in ASGM-impacted soils, they were relatively immobile under oxidising conditions around pH 8.5 because of their retention via adsorption to hydrous ferric oxides (HFOs), montmorillonite and kaolinite. In contrast, Cu and As release from the historic ASGM site samples exceeded the environmental limits for Class A and Class C effluents, which could be attributed to the removal of calcite and dolomite by weathering. The enhanced desorption of As at around pH 8.5 also likely contributed to its release from these soils.


Assuntos
Mineração , Poluentes do Solo/análise , Poluentes do Solo/química , Solo/química , Arsênico/análise , Arsênico/química , Cobre/análise , Cobre/química , Ouro/análise , Ferro/química , Compostos de Ferro/química , Chumbo/análise , Chumbo/química , Minerais/química , Filipinas , Sulfetos/química , Difração de Raios X , Zinco/análise , Zinco/química
4.
Food Chem ; 328: 127091, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32474237

RESUMO

Methanol is highly toxic for human, so methanol detection is valuable especially in water and ethanol medium without complicated and time consuming procedure. In this work, we present a new fluorescence probe for direct detection of methanol in aqueous and ethanol medium based on the ZnS:Mn2+ quantum dot (QDs) and soluble N-methylpolypyrrole (NMPPy) hybrid. Moreover, the number of spectroscopic techniques were used to study the chemical composition and optical properties of the resultant QDs as well as investigation on the sensing mechanism toward methanol. Also, methanol can be determined by using ZnS:Mn2+ QDs/NMPPy hybrid based switchable fluorescence sensing system, with high sensitivity, high selectivity and a very good detection limit of 1 mM with linearity in the concentration range of 25-230 mM (~0.1-0.9% v/v) in aqueous solution. Finally, the ZnS:Mn2+ QDs/NMPPy hybrid as optical sensor was successfully utilized to determine the amount of methanol in real alcoholic beverage samples.


Assuntos
Etanol/química , Metanol/análise , Polímeros/química , Pirróis/química , Pontos Quânticos/química , Espectrometria de Fluorescência/instrumentação , Sulfetos/química , Água/química , Compostos de Zinco/química , Corantes Fluorescentes/química , Humanos , Limite de Detecção , Magnésio/química , Metanol/química
5.
Ecotoxicol Environ Saf ; 200: 110744, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32460050

RESUMO

Hematite nanoparticles (α-Fe2O3 NPs) were successfully synthesized by a low-cost solvent-free reaction using Ferrous sulfate waste (FeSO4·7H2O) and pyrite (FeS2) as raw materials and employed for the decolorization of Methyl Orange by the photo-Fenton system. The properties of α-Fe2O3 NPs before and after photo-Fenton reaction were characterized by X-ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectrum and X-ray photoelectron spectroscopy (XPS), and the optical properties of α-Fe2O3 NPs were analyzed by UV-vis diffuse reflectance spectra (UV-vis DRS) and Photoluminescence (PL) spectra. The analytic results showed that the as-formed samples having an average diameter of ~50 nm exhibit pure phase hematite with sphere structure. Besides, little differences were found by comparing the characterization data of the particles before and after the photo-Fenton reaction, indicating that the photo-Fenton reaction was carried out in solution rather than on the surface of α-Fe2O3 NPs. A 24 central composite design (CCD) coupled with response surface methodology (RSM) was applied to evaluate and optimize the important variables. A significant quadratic model (P-value<0.0001, R2 = 0.9664) was derived using an analysis of variance (ANOVA), which was adequate to perform the process variables optimization. The optimal process conditions were performed to be 395 nm of the light wavelength, pH 3.0, 5 mmol/L H2O2 and 1 g/L α-Fe2O3, and the decolorization efficiency of methyl orange was 99.55% at 4 min.


Assuntos
Compostos Azo/química , Corantes/química , Compostos Férricos/química , Nanopartículas Metálicas/química , Catálise , Compostos Férricos/síntese química , Compostos Ferrosos/química , Ferro/química , Solventes , Sulfetos/química
6.
Food Chem ; 324: 126889, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32353659

RESUMO

Pesticides have been extensively applied worldwide to protect crops from worms and insects; however, the continuous use of pesticides affects ecosystems, agricultural product safety, nontarget organisms, and human health. In this paper, we report a highly sensitive biosensor for the determination of pesticides based on tin sulfide (SnS2) and chitosan (CHIT) nanocomposites decorated with a unique British housefly acetylcholinesterase (AChE). The hydrothermally synthesized nano-SnS2 mixed with chitosan solution (CHIT-SnS2) was drop-casted onto a glassy carbon electrode (GCE). Subsequently, the British housefly AChE was immobilized on the CHIT/SnS2-coated GCE that was then employed for pesticide detection. The developed biosensor showed an ultra-high sensitivity and wide linear detection range from 0.02 nM to 20000 nM with a detection limit of 0.02 nM for the detection of chlorpyrifos as the model pesticide. Furthermore, the AChE/CHIT-SnS2/GCE exhibited acceptable storage stability, good reproducibility, and selectivity.


Assuntos
Acetilcolinesterase/metabolismo , Técnicas Biossensoriais/métodos , Quitosana/química , Moscas Domésticas/enzimologia , Compostos Organofosforados/análise , Sulfetos/química , Compostos de Estanho/química , Acetilcolinesterase/química , Animais , Carbono/química , Clorpirifos/análise , Técnicas Eletroquímicas , Eletrodos , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Limite de Detecção , Nanocompostos/química , Praguicidas/análise , Reprodutibilidade dos Testes
7.
Arch Biochem Biophys ; 687: 108391, 2020 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-32360749

RESUMO

Hydropersulfides are reported to be good biological reductants, superior to thiols and akin to selenols. As such, they have been previously shown to reduce metalloproteins such as ferric myoglobin and ferric cytochrome c to their ferrous forms under conditions where little or no reduction from corresponding thiols is observed. Not surprisingly, the reduction of ferric myoglobin to ferrous myoglobin under aerobic conditions results in the generation of oxymyoglobin (dioxygen bound ferrous myoglobin). Previous studies have demonstrated that oxymyoglobin can also act as an oxidant with highly reducing species such as hydroxylamine and ascorbate. Considering the reducing properties of hydropersulfides, it is possible that they can also react with oxymyoglobin similarly to hydroxylamine or ascorbate. Herein, this reaction is examined and indeed hydropersulfides are found to react with oxymyoglobin similarly to other reducing species leading to a fleeting ferric myoglobin which is rapidly reduced to the ferrous form also by hydropersulfide.


Assuntos
Mioglobina/química , Sulfetos/química , Animais , Ácido Ascórbico/química , Bovinos , Cavalos , Hidroxilamina/química , Modelos Químicos , Oxirredução , Oxigênio/química , Penicilamina/análogos & derivados
8.
Chemosphere ; 253: 126662, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32268253

RESUMO

In this study, pyrite (FeS2) was used as a novel activator of calcium peroxide (CaO2) for the degradation of diethyl phthalate (DEP) in both aqueous solution and soil. DEP (10 mg/L) in aqueous solution was completely degraded within 5.0 min by the FeS2 (0.30 g/L)/CaO2 (1.0 mM) system at pH 3.5. X-ray diffraction (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), free radical quenching, and X-ray photoelectron spectroscopy (XPS) were used to elucidate the mechanism of the catalytic decomposition of CaO2, radical formation and DEP degradation in the presence of by pyrite. The results show that hydroxyl radicals (OH) are the dominant active species responsible for DEP degradation. Surface or lattice Fe(II) of FeS2 readily activates H2O2 generated by CaO2 decomposition to produce OH, while the reducing sulfur species of FeS2 promotes the regeneration of surface of Fe(II) that catalyzes the production of additional OH, leading to the efficiently oxidative degradation of DEP. Although high concentration of common anions, such as Cl-, NO3-, SO42-, and HCO3-, exert inhibitory effects on DEP degradation by pyrite/CaO2, the reaction system can still efficiently degrade DEP in realistic soil. It was observed that 78% of DEP (25 mg kg-1) was degraded by 2.5% CaO2 (w/w) and 0.5% FeS2 (w/w) within 24 h. These results provide new insight into the mechanistic processes of CaO2 activation and OH formation by the novel FeS2 catalyst, demonstrating a promising alternative to the traditional H2O2-base Fenton process for contaminated soil remediation.


Assuntos
Ferro/química , Peróxidos/química , Ácidos Ftálicos/química , Sulfetos/química , Catálise , Espectroscopia de Ressonância de Spin Eletrônica , Radicais Livres , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Oxirredução , Espectroscopia Fotoeletrônica , Enxofre
9.
Int J Nanomedicine ; 15: 1951-1965, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32256071

RESUMO

Introduction: Indium phosphide (InP) quantum dots (QDs) have shown a broad application prospect in the fields of biophotonics and nanomedicine. However, the potential toxicity of InP QDs has not been systematically evaluated. In particular, the effects of different surface modifications on the biodistribution and toxicity of InP QDs are still unknown, which hinders their further developments. The present study aims to investigate the biodistribution and in vivo toxicity of InP/ZnS QDs. Methods: Three kinds of InP/ZnS QDs with different surface modifications, hQDs (QDs-OH), aQDs (QDs-NH2), and cQDs (QDs-COOH) were intravenously injected into BALB/c mice at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively. Biodistribution of three QDs was determined through cryosection fluorescence microscopy and ICP-MS analysis. The subsequent effects of InP/ZnS QDs on histopathology, hematology and blood biochemistry were evaluated at 1, 3, 7, 14 and 28 days post-injection. Results: These types of InP/ZnS QDs were rapidly distributed in the major organs of mice, mainly in the liver and spleen, and lasted for 28 days. No abnormal behavior, weight change or organ index were observed during the whole observation period, except that 2 mice died on Day 1 after 25 mg/kg BW hQDs treatment. The results of H&E staining showed that no obvious histopathological abnormalities were observed in the main organs (including heart, liver, spleen, lung, kidney, and brain) of all mice injected with different surface-functionalized QDs. Low concentration exposure of three QDs hardly caused obvious toxicity, while high concentration exposure of the three QDs could cause some changes in hematological parameters or biochemical parameters related to liver function or cardiac function. More attention needs to be paid on cQDs as high-dose exposure of cQDs induced death, acute inflammatory reaction and slight changes in liver function in mice. Conclusion: The surface modification and exposure dose can influence the biological behavior and in vivo toxicity of QDs. The surface chemistry should be fully considered in the design of InP-based QDs for their biomedical applications.


Assuntos
Pontos Quânticos/toxicidade , Animais , Análise Química do Sangue , Feminino , Índio/química , Camundongos Endogâmicos BALB C , Microscopia de Fluorescência , Fosfinas/química , Pontos Quânticos/química , Sulfetos/química , Propriedades de Superfície , Distribuição Tecidual , Compostos de Zinco/química
10.
Phys Chem Chem Phys ; 22(12): 6706-6715, 2020 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-32162626

RESUMO

In the present study, we systematically investigated the adsorption mechanism of canonical DNA nucleobases and their two nucleobase pairs on a single-layer gallium sulfide (GaS) substrate using DFT+D3 methods. The GaS substrate has chemical interactions with molecules 0.02 |e| 0.11 |e| from molecules to the monolayer GaS surface. Due to the chemical interactions of adenine, cytosine, guanine, and thymine on the monolayer GaS surface, the work function is decreased by 0.69, 0.60, 0.97, and 0.20 eV, respectively. It is displayed that the bandgap of the monolayer GaS sheet can be significantly affected as induced molecular electronic states tend to appear near the Fermi level region due to chemical and physisorption mechanism. We have also investigated the transport properties of DNA nucleobases, namely, AT and GC pair molecules on the GaS surface, which shows significant reduction in the zero-bias transmission spectra. Moreover, with and without DNA nucleobases, namely, AT and GC pair molecules' absorptions on the GaS surface, clearly expressed in terms of distinct current signals, can be observed as ON and OFF states for this device. The distinctive nucleobase adsorption energies and different I-V responses may serve as potential probes for the selective detection of nucleobase molecules in imminent DNA sequencing applications based on a monolayer GaS surface.


Assuntos
Sequência de Bases , DNA/química , Gálio/química , Sulfetos/química , DNA/análise , Estrutura Molecular
11.
Int J Nanomedicine ; 15: 137-149, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32021170

RESUMO

Purpose: Traditional chemotherapy is accompanied by significant side effects, which, in many aspects, limits its treatment efficacy and clinical applications. Herein, we report an oxidative responsive polymersome nanosystem mediated by near infrared (NIR) light which exhibited the combination effect of photodynamic therapy (PDT) and chemotherapy. Methods: In our study, poly (propylene sulfide)20-bl-poly (ethylene glycol)12 (PPS20-b-PEG12) block copolymer was synthesized and employed to prepare the polymersome. The hydrophobic photosensitizer zinc phthalocyanine (ZnPc) was loaded in the shell and the hydrophilic doxorubicin hydrochloride (DOX·HCl) in the inner aqueous space of the polymersome. Results: Under the irradiation of 660 nm NIR light, singlet oxygen 1O2 molecules were generated from ZnPc to oxidize the neighbouring sulfur atoms on the PPS block which eventually ruptured the intact structure of polymersomes, leading to the release of encapsulated DOX·HCl. The released DOX and the 1O2 could achieve a combination effect for cancer therapy if the laser activation and drug release occur at the tumoral sites. In vitro studies confirmed the generation of singlet oxygen and DOX release by NIR irradiation. In vivo studies showed that such a combined PDT-chemotherapy nanosystem could accumulate in A375 tumors efficiently, thus leading to significant inhibition on tumor growth as compared to PDT (PZ group) or chemotherapy alone (DOX group). Conclusion: In summary, this oxidation-sensitive nanosystem showed excellent anti-tumor effects by synergistic chemophotodynamic therapy, indicating that this novel drug delivery strategy could potentially provide a new means for cancer treatments in clinic.


Assuntos
Doxorrubicina/administração & dosagem , Sistemas de Liberação de Medicamentos/métodos , Melanoma Experimental/tratamento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/administração & dosagem , Animais , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/farmacocinética , Linhagem Celular Tumoral , Doxorrubicina/farmacocinética , Liberação Controlada de Fármacos , Humanos , Indóis/administração & dosagem , Indóis/química , Lasers , Masculino , Camundongos Endogâmicos BALB C , Nanoestruturas/administração & dosagem , Nanoestruturas/química , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/química , Fármacos Fotossensibilizantes/química , Polietilenoglicóis/química , Polímeros/química , Oxigênio Singlete/farmacocinética , Sulfetos/química
12.
J Photochem Photobiol B ; 204: 111799, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32018156

RESUMO

CdSe/CdS core shelled quantum dots (QDs) were prepared by colloidal synthesis using a binary ligand system and a non-coordinating, reusable solvent n-octadecane (nOD). Both the synthesis of CdSe and CdSe/CdS core shelled quantum dots were achieved by hot injection technique at much lower temperatures than reported earlier. The use of binary ligand facilitated enough nucleation and growth. Red shift in absorption spectra, an enhanced crystallite and particle size is evidenced by XRD and TEM respectively, confirming the formation of core shell structure of CdSe/CdS. The synthesized core shells exhibited high fluorescence intensity, long term stability and good mono dispersion, making it a potential material for bio-imaging and sensing. Core shell QDs were modified with mercapto propionic acid (MPA) to impart aqueous solubility. Studies on cytotoxicity of shelled QDs reveal good bio compatibility with a very minimum toxicity of IC50 = 20 µg/L. These QDs were used for sensing E. coli. Ordinary glass slide, modified using plasma etching is surface modified through APTES aiding conjugation of antibodies. Anti- E. coli polyclonal antibody on glass matrix (slide) and antibody conjugated QDs were used for detection of E. coli in a typical sandwich model. The excellent optical transparency of glass and high emission of QDs lead to detection of E.coli with a limit of detection of 50 CFU/mL.


Assuntos
Escherichia coli/efeitos dos fármacos , Vidro/química , Pontos Quânticos/química , Animais , Compostos de Cádmio/química , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Camundongos , Microscopia de Fluorescência , Pontos Quânticos/toxicidade , Compostos de Selênio/química , Sulfetos/química , Propriedades de Superfície
13.
Anal Bioanal Chem ; 412(8): 1893-1899, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32016568

RESUMO

Superoxide dismutase (SOD), also known as liver protein, is a substance widely distributed in various biological cells. It has the function of catalyzing the disproportionation reaction of superoxide free radicals. SOD can form an antioxidant chain together with peroxidase, catalase, and other substances in the body of organisms, and thus, is one of the indispensable important substances in the body of organisms. In this work, we provided a simple and fast visual electrochemiluminescence (ECL) sensor for SOD detection. CuInZnS quantum dots (QDs) worked as the ECL luminophore with hydrogen peroxide as co-reactant. In the sensing process, SOD and CuInZnS QDs on a glassy carbon electrode (GCE) competed with each other for hydrogen peroxide to produce superoxide during electrochemical luminescence, thus quenching the ECL signal of CuInZnS QDs. The proposed sensor can quantify SOD with a limit of detection (LOD) of 0.03 µg/mL. In addition, the change in the CuInZnS QDs ECL signal was easily observed with a smartphone camera. The results indicated that this sensor could effectively work in the detection of SOD in human blood. Graphical abstract.


Assuntos
Cobre/química , Técnicas Eletroquímicas/métodos , Índio/química , Luminescência , Pontos Quânticos/química , Sulfetos/química , Superóxido Dismutase/análise , Compostos de Zinco/química , Técnicas Biossensoriais , Limite de Detecção , Reprodutibilidade dos Testes
14.
Chem Commun (Camb) ; 56(19): 2909-2912, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32037421

RESUMO

Herein, a triple-helix molecular switch photoelectrochemical (PEC) biosensor is developed for ultrasensitive and selective detection of microRNA based on position-controllable CdS//CdTe signal enhancement and switching accompanying the signal amplification of a three-dimensional DNA walking machine. The developed PEC biosensor exhibits excellent analytical performance for microRNA-141 detection with a wide linear range from 5 aM to 100 fM, a low detection limit of 1.3 aM and outstanding selectivity.


Assuntos
Técnicas Biossensoriais , Compostos de Cádmio/química , Técnicas Eletroquímicas/instrumentação , MicroRNAs/análise , Processos Fotoquímicos , Sulfetos/química , Telúrio/química , DNA/química , Limite de Detecção
15.
Chemosphere ; 249: 126130, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32058134

RESUMO

In this study, the effect of ball milling on pyrite (FeS2) promoting arsenic (As) removal by zero-valent iron (Fe0) was investigated. The influences of different mass ratios of ball-milled FeS2/Fe0, the dosage of ball-milled FeS2/Fe0 used and initial pH value were evaluated by batch experiments. The results showed that the ball-milled FeS2/Fe0 system had a higher total As removal efficiency than the mixed FeS2-Fe0 system, ball-milled FeS2 and ball-milled Fe0 systems in equal mass. Higher As removal efficiency in ball-milled FeS2/Fe0 system was primarily related to the accelerated corrosion of Fe0, which was supported by the determination of total Fe2+ release and electrochemical experiments. SEM-EDS and XPS characterizations revealed that there were iron sulfides (Fe(II)-S and Fe(III)-S) produced on the surface of Fe0 in ball-milled FeS2/Fe0, which could facilitate the electron transfer of Fe0 and enhanced the corrosion of it. BET test also indicated that ball-milled FeS2/Fe0 possessed a higher specific surface area than ball-milled Fe0. In addition, the results also showed the optimum mass ratio of FeS2 and Fe0 in ball-milled FeS2/Fe0 to remove As ([As(III)] = 2 mg/L) was 1:1, and the optimum dosage was 0.5 g/L, thereby indicating the optimal As:Fe0 molar ratio was about 1:168. And the removal rate of As by ball-milled FeS2/Fe0 was faster in acidic condition than that in alkaline condition. These findings suggest that Fe0-based arsenic removal efficiency can be enhanced by ball-milling with FeS2, making it more feasible for remediation of arsenic-polluted water.


Assuntos
Arsênico/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Arsênico/análise , Corrosão , Compostos Férricos , Compostos Ferrosos , Ferro/química , Sulfetos/química , Água , Poluentes Químicos da Água/análise
16.
Chemosphere ; 244: 125568, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050347

RESUMO

Persulfate (PS) is widely used for environmental remediation, but its organic contaminant removal performance strongly depends on its activation. In this study, we demonstrate that pyrite (FeS2) can more effectively activate PS than the commonly used FeSO4 for atrazine degradation. When 3.0 mM of PS and 4.2 mM of iron salts were used, the atrazine degradation efficiency of FeS2/PS was 1.4 times that of FeSO4/PS, while the amount of consumed PS in case of FeS2 was only 53% of that by FeSO4. The better PS activation performance of FeS2 could be attributed to its slow and sustainable release of dissolved Fe(II), inhibiting the quenching reaction between •SO4-/•OH and Fe(II) ions, and thus producing more reactive oxygen species for the atrazine degradation. More importantly, the surface bound Fe(II) of FeS2 could activate molecular oxygen to generate superoxide radical (•O2-), which could further promote the effective decomposition of PS by accelerating the Fe(III)/Fe(II) redox cycle. This study unravels the roles of dissolved Fe(II) and surface bound Fe(II) on the persulfate activation, and provides a promising heterogeneous persulfate activator for pollutant control and environmental remediation.


Assuntos
Atrazina/química , Ferro/química , Sulfetos/química , Poluentes Químicos da Água/química , Compostos Benzidrílicos , Compostos Férricos , Oxirredução , Sulfatos , Poluentes Químicos da Água/análise
17.
J Agric Food Chem ; 68(10): 3228-3237, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32074447

RESUMO

Effects of natural catalysts, isothiocyanates and polysulfides, on Z-isomerization and decomposition of (all-E)-carotenoids (lycopene, ß-carotene, and astaxanthin) after heat treatment were investigated. When isothiocyanates were added to (all-E)-carotenoid solutions and heated, Z-isomerization and decomposition of carotenoids were enhanced and the degree differed depending on the isothiocyanate type. Interestingly, when polysulfides were applied in the same manner, in addition to promoting the Z-isomerization reaction, they markedly improved the thermal stability of carotenoids. Successively, we investigated the reaction characteristics of allyl isothiocyanate (AITC) and diallyl disulfide (DADS) using (all-E)-lycopene; that is, effects of the amount added, solvent used, and reaction temperature and time, as well as the combination use on Z-isomerization and decomposition of lycopene, were investigated. With increases in the amount added and reaction temperature and time, Z-isomerization of lycopene was promoted for both catalysts. The high-temperature treatment tests clearly showed that AITC induced thermal decomposition of lycopene, whereas DADS improved the lycopene stability. Moreover, the simultaneous use of AITC and DADS resulted in a synergetic effect on the Z-isomerization efficiency.


Assuntos
Carotenoides/química , Isotiocianatos/química , Sulfetos/química , Catálise , Isomerismo , Licopeno/química , Xantofilas/química , beta Caroteno/química
18.
Food Chem ; 316: 126352, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32062232

RESUMO

This study investigates the relationship between the two main forms of Cu in wine and their impact on the rate of oxygen consumption. The Cu forms were differentiated by medium exchange constant current stripping potentiometry, which classified the Cu as either bound to sulfide or not. Oxygen consumption rates were determined in red, white and model wines after saturation with oxygen. The results for white wines showed that the oxygen consumption was sensitive to the non-sulfide-bound Cu concentration when ascorbic acid was present, and the first order rates ranged from 0.02 to 0.11 h-1. However, the same was not true for wines without added ascorbic acid that showed little influence of Cu form on oxygen decay rates. Cu forms were also found to significantly change in some wines during the oxygen decay experiment. Ascorbic acid is critical in enabling the form of Cu to significantly influence the oxygen reaction rate in wine.


Assuntos
Cobre/química , Oxigênio/química , Sulfetos/química , Vinho/análise , Estrutura Molecular , Potenciometria
19.
Dalton Trans ; 49(10): 3243-3252, 2020 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-32096513

RESUMO

A series of cationic Ru(ii)(η6-p-cymene) complexes with thioether-functionalised N-heterocyclic carbene ligands have been prepared and fully characterized. Steric and electronic influence of the R thioether substituent on the coordination of the sulfur atom was investigated. The molecular structure of three of them has been determined by means of X-ray diffractrometry and confirmed the bidentate (κ2-C,S) coordination mode of the ligand. Interestingly, only a single diastereomer, as an enantiomeric couple, was observed in the solid state for complexes 1c, 1i and 1j. DFT calculations established a low energy inversion barrier between the two diastereomers through a sulfur pyramidal inversion pathway with R donating group while a dissociative/associative mechanism is more likely with R substituents that contain electron withdrawing group, thus suggesting that the only species observed by the 1H-NMR correspond to an average resonance position of a fluxional mixtures of isomers. All these complexes were found to catalyse the oxydant-free double dehydrogenation of primary amine into nitrile. Ru complex bearing NHC-functionalised S-tBu group was further investigated in a wide range of amines and was found more selective for alkyl amine substrates than for benzylamine derivatives. Finally, preliminary results of the biological effects on various human cancer cells of four selected Ru complexes are reported.


Assuntos
Complexos de Coordenação/química , Rutênio/química , Catálise , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/farmacologia , Humanos , Ligantes , Rutênio/farmacologia , Sulfetos/química
20.
Nanoscale ; 12(9): 5332-5340, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-32090217

RESUMO

Bicontinuous nanospheres (BCNs) are underutilized self-assembled nanostructures capable of simultaneous delivery of both hydrophilic and hydrophobic payloads. Here, we demonstrate that BCNs assembled from poly(ethylene glycol)-block-poly(propylene sulfide) (PEG-b-PPS), an oxidation-sensitive copolymer, are stably retained within cell lysosomes following endocytosis, resisting degradation and payload release for days until externally triggered. The oxygen scavenging properties and enhanced stability of the bicontinuous PEG-b-PPS nanoarchitecture significantly protected cells from typically cytotoxic application of pro-apoptotic photo-oxidizer pheophorbide A and chemotherapeutic camptothecin. The photo-oxidation triggered transition from a bicontinuous to micellar morphology overcame this stability, allowing on-demand cytosolic delivery of camptothecin for enhanced control over off-on cytotoxicity. These results indicate that inducible transitions in the nanostructure morphology can influence intracellular stability and toxicity of self-assembled nanotherapeutics.


Assuntos
Citosol/metabolismo , Luz , Micelas , Nanoestruturas/química , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Camptotecina/química , Camptotecina/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Clorofila/análogos & derivados , Clorofila/química , Clorofila/farmacologia , Portadores de Fármacos/química , Endocitose , Lisossomos/metabolismo , Camundongos , Oxirredução , Polietilenoglicóis/química , Células RAW 264.7 , Oxigênio Singlete/química , Oxigênio Singlete/metabolismo , Sulfetos/química
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