RESUMO
Accurate detection of labile analytes through activity based fluorogenic sensing is meaningful but remains a challenge because of nonrapid reaction kinetic. Herein, we present a signaling reporter engineering strategy to accelerate azoreduction reaction by positively charged fluorophore promoted unstable anion recognition for rapidly sensing sodium dithionite (Na2S2O4), a kind of widespread used but harmful inorganic reducing agent. Its quick decomposition often impedes application reliability of traditional fluorogenic probes in real samples because of their slow responses. In this work, four azo-based probes with different charged fluorophores (positive, zwitterionic, neutral, and negative) were synthesized and compared. Among of them, with sequestration effect of positively charged anthocyanin fluorophore for dithionite anion via electrostatic attraction, the cationic probe Azo-Pos displayed ultrafast fluorogenic response (â¼2 s) with the fastest response kinetic (kpos' = 0.373 s-1) that is better than other charged ones (kzwi' = 0.031 s-1, kneu' = 0.013 s-1, kneg' = 0.003 s-1). Azo-Pos was demonstrated to be capable to directly detect labile Na2S2O4 in food samples and visualize the presence of Na2S2O4 in living systems in a timely fashion. This new probe has potential as a robust tool to fluorescently monitor excessive food additives and biological invasion of harmful Na2S2O4. Moreover, our proposed accelerating strategy would be versatile to develop more activity-based sensing probes for quickly detecting other unstable analytes of interest.
Assuntos
Corantes Fluorescentes , Corantes Fluorescentes/química , Humanos , Ditionita/química , Compostos Azo/química , CinéticaRESUMO
Dithionite remained in the foodstuff may pose a great threat to the health of consumers. Three xanthylium-based probes were synthesized and their responses to dithionite were explored. Probe SH-1 could respond to dithionite selectively in PBS buffer (15% DMSO, 10 mM, pH = 7.4). Upon the addition of dithionite, the fluorescent emission of SH-1 at 684 nm dropped quickly (within 10 s) and the fluorescence decline was proportional to the concentration of dithionite (0-7.0 µM). The limit of detection was determined to be 0.139 µM. Then, the sensing mechanism was tentatively presented and the structure of resulted adduct (SH-1-SO3-) which was the reaction product of SH-1 and dithionite via a Micheal addition reaction followed by an oxidation reaction was verified. Moreover, white granulated sugar was subjected to the standard spike experiments and the results demonstrated a great potential of SH-1 for the quantitative monitoring of dithionite in foodstuffs.
Assuntos
Ditionita , Corantes Fluorescentes , Corantes Fluorescentes/química , Ditionita/química , Espectrometria de Fluorescência , Contaminação de Alimentos/análise , Limite de Detecção , Açúcares/química , Açúcares/análiseRESUMO
The light-driven reduction of dinitrogen (N2) to ammonia (NH3) catalyzed by a cadmium sulfide (CdS) nanocrystalnitrogenase MoFe protein biohybrid is dependent on a range of different factors, including an appropriate hole-scavenging sacrificial electron donor (SED). Here, the impact of different SEDs on the overall rate of N2 reduction catalyzed by a CdS quantum dot (QD)-MoFe protein system was determined. The selection of SED was guided by several goals: (i) molecules with standard reduction potentials sufficient to reduce the oxidized CdS QD, (ii) molecules that do not absorb the excitation wavelength of the CdS QD, and (iii) molecules that could be readily reduced by sustainable processes. Earlier studies utilized buffer molecules or ascorbic acid as the SED. The effectiveness of ascorbic acid as SED was compared to dithionite (DT), triethanolamine (TEOA), and hydroquinone (HQ) across a range of concentrations in supporting N2 reduction to NH3 in a CdS QD-MoFe protein photocatalytic system. It was found that TEOA supported N2 reduction rates comparable to those observed for dithionite and ascorbic acid. HQ was found to support significantly higher rates of N2 reduction compared to the other SEDs at a concentration of 50 mM. A comparison of the rates of N2 reduction by the biohybrid complex to the standard reduction potential (Eo) of the SEDs reveals that Eo is not the only factor impacting the efficiency of hole-scavenging. These findings reveal the importance of the SED properties for improving the efficiency of hole-scavenging in the light-driven N2 reduction reaction catalyzed by a CdS QD-MoFe protein hybrid.
Assuntos
Azotobacter vinelandii , Compostos de Cádmio , Nitrogenase , Sulfetos , Nitrogenase/metabolismo , Molibdoferredoxina/metabolismo , Oxirredução , Ditionita/metabolismo , Catálise , Ácido Ascórbico/metabolismo , Azotobacter vinelandii/metabolismoRESUMO
Structural Fe in clay minerals is an important, potentially renewable source of electron equivalents for contaminant reduction, yet our knowledge of how clay mineral Fe reduction pathways and Fe reduction extent affect clay mineral Fe(II) reactivity is limited. Here, we used a nitroaromatic compound (NAC) as a reactive probe molecule to assess the reactivity of chemically reduced (dithionite) and Fe(II)-reduced nontronite across a range of reduction extents. We observed biphasic transformation kinetics for all nontronite reduction extents of ≥5% Fe(II)/Fe(total) regardless of the reduction pathway, indicating that two Fe(II) sites of different reactivities form in nontronite at environmentally relevant reduction extents. At even lower reduction extents, Fe(II)-reduced nontronite completely reduced the NAC whereas dithionite-reduced nontronite could not. Our 57Fe Mössbauer spectroscopy, ultraviolet-visible spectroscopy, and kinetic modeling results suggest that the highly reactive Fe(II) entities likely comprise di/trioctahedral Fe(II) domains in the nontronite structure regardless of the reduction mechanism. However, the second Fe(II) species, of lower reactivity, varies and for Fe(II)-reacted NAu-1 likely comprises Fe(II) associated with an Fe-bearing precipitate formed during electron transfer from aqueous to nontronite Fe. Both our observation of biphasic reduction kinetics and the nonlinear relationship of rate constant and clay mineral reduction potential EH have major implications for contaminant fate and remediation.
Assuntos
Compostos Ferrosos , Minerais , Argila , Ditionita , Oxirredução , Minerais/química , Compostos Ferrosos/química , Compostos Férricos/químicaRESUMO
Radical S-adenosyl-l-methionine (SAM) enzymes are ubiquitous in nature and carry out a broad variety of difficult chemical transformations initiated by hydrogen atom abstraction. Although numerous radical SAM (RS) enzymes have been structurally characterized, many prove recalcitrant to crystallization needed for atomic-level structure determination using X-ray crystallography, and even those that have been crystallized for an initial study can be difficult to recrystallize for further structural work. We present here a method for computationally engineering previously observed crystallographic contacts and employ it to obtain more reproducible crystallization of the RS enzyme pyruvate formate-lyase activating enzyme (PFL-AE). We show that the computationally engineered variant binds a typical RS [4Fe-4S]2+/+ cluster that binds SAM, with electron paramagnetic resonance properties indistinguishable from the native PFL-AE. The variant also retains the typical PFL-AE catalytic activity, as evidenced by the characteristic glycyl radical electron paramagnetic resonance signal observed upon incubation of the PFL-AE variant with reducing agent, SAM, and PFL. The PFL-AE variant was also crystallized in the [4Fe-4S]2+ state with SAM bound, providing a new high-resolution structure of the SAM complex in the absence of substrate. Finally, by incubating such a crystal in a solution of sodium dithionite, the reductive cleavage of SAM is triggered, providing us with a structure in which the SAM cleavage products 5'-deoxyadenosine and methionine are bound in the active site. We propose that the methods described herein may be useful in the structural characterization of other difficult-to-resolve proteins.
Assuntos
Acetiltransferases , S-Adenosilmetionina , Acetiltransferases/química , Acetiltransferases/metabolismo , Domínio Catalítico , Cristalização , Ditionita , Espectroscopia de Ressonância de Spin Eletrônica , Proteínas Ferro-Enxofre/química , Proteínas Ferro-Enxofre/metabolismo , Metionina/metabolismo , Oxirredução , S-Adenosilmetionina/metabolismoRESUMO
It is of great scientific and practical importance to explore the mechanisms of accelerated degradation of Hexachlorobenzene (HCB) in soil. Both iron oxide and dithionite may promote the reductive dechlorination of HCB, but their effects on the microbial community and the biotic and abiotic mechanisms behind it remain unclear. This study investigated the effects of goethite, dithionite, and their interaction on microbial community composition and structure, and their potential contribution to HCB dechlorination in a paddy soil to reveal the underlying mechanism. The results showed that goethite addition alone did not significantly affect HCB dechlorination because the studied soil lacked iron-reducing bacteria. In contrast, dithionite addition significantly decreased the HCB contents by 44.0-54.9%, while the coexistence of dithionite and goethite further decreased the HCB content by 57.9-69.3%. Random Forest analysis suggested that indicator taxa (Paenibacillus, Acidothermus, Haliagium, G12-WMSP1, and Frankia), Pseudomonas, richness and Shannon's index of microbial community, and immobilized Fe content were dominant driving factors for HCB dechlorination. The dithionite addition, either with or without goethite, accelerated HCB anaerobic dechlorination by increasing microbial diversity and richness as well as the relative abundance of the above specific bacterial genera. When goethite and dithionite coexist, sulfidation of goethite with dithionite could remarkably increase FeS formation and then further promote HCB dechlorination rates. Overall, our results suggested that the combined application of goethite and dithionite could be a practicable strategy for the remediation of HCB contaminated soil.
Assuntos
Poluentes do Solo , Solo , Solo/química , Hexaclorobenzeno , Ditionita/metabolismo , Poluentes do Solo/análise , Bactérias/metabolismoRESUMO
Arsenic (As) mobilisation assists in remediating As-contaminated soils but might increase ecological and health risks. In this study, risks of applying two mobilising agents were assessed, i.e. an emerging reducing-chelating composite agent [dithionite (Na2S2O4)-EDTA] and a classical low-molecular-weight organic acid (LMWOA) [citric acid (C6H8O7)]. Results showed that both agents induced sharp increase in leachability-based ecological risk of As. Interestingly, the two agents had opposite performances regarding health risks. Na2S2O4-EDTA significantly increased As relative bioavailability (RBA) to 1.83 times that in controls based on in vivo mouse model, and As bioaccessibility to 1.96, 1.65 and 1.20 times in gastric, small intestinal and colon phases based on in vitro PBET-SHIME model. Besides, it caused significant increase of highly toxic As(â ¢) in colon fluid. In contrast, C6H8O7 significantly reduced RBA and bioaccessibility of soil As in colon by 44.44% and 14.65%, respectively. Importantly, C6H8O7 restrained bioaccessible As(V) reduction and promoted bioaccessible As(â ¢) methylation, further reducing health risk. The phenomena could mainly be attributed to excessive metal components release from soil by C6H8O7 and gut microbiota metabolism of C6H8O7. In summary, C6H8O7 and similar LMWOAs are recommended. The study contributes to mobilising agent selection and development and provides a reference for managing remediation sites.
Assuntos
Arsênio , Animais , Camundongos , Ditionita , Arsênio/toxicidade , Disponibilidade Biológica , Ácido Cítrico , Ácido Edético , SoloRESUMO
Modifying PVDF membrane by blending hydrophilic nano TiO2 has been highly concerning, but its practical application is not well investigated. In this study, PVDF-TiO2 membrane was employed in two modes to treat micro-polluted raw water for the first time, direct membrane filtration and pre-oxidation assists membrane filtration. At two filtration modes, the PVDF-TiO2 membrane had comparable rejection capability to the unmodified PVDF membrane, as the removal of permanganate index (CODMn) was 0.26-0.72 mg/L, UV254 was 0.0070-0.0618 cm-1, turbidity was 1.60-4.49 NTU, and the total number of colonies was 360-23,780 CFU/mL. As for raw water treatment, using Fe2+/sodium dithionite (DTN)/O2 system as the pre-oxidation process to assist the filtration of the PVDF-TiO2 membrane was feasible. After optimization, the applicable conditions of the Fe2+/DTN/O2 process were DTN dosage at 100 mg/L and a CFe/CDTN of 1:4. As a result, the effluent qualities of the PVDF-TiO2 membrane significantly improved. It was investigated that atrazine (ATZ), CODMn, UV254, and turbidity reduced, which was realized by the synergic effects of the pre-oxidation by free radicals and flocculation by iron. Pre-oxidation of the Fe2+/DTN/O2 process could also enhance the permeability of the PVDF-TiO2 membrane from 53.6 to 58.0 L/(m2·h), nearly two times the PVDF membrane. Besides, the practical fouling of the PVDF-TiO2 membrane was stably alleviated by the reduced Rt, Rre, and Rir, mainly due to constraining the internal pore fouling effectively.
Assuntos
Membranas Artificiais , Purificação da Água , Ditionita , Recursos Hídricos , PolivinilRESUMO
Whereas dithionite has been extensively used as a reducing agent in soil and sediment remediation, here, we demonstrate that it can be used as a potential source of oxidizing radical in oxic soils with potential application in organic pollutant remediation. Benzoic acid was used as a probe compound and the generation of its oxidative product para-hydroxybenzoic acid (p-HBA) was detected to quantify the production of oxidative radicals (ROS). By increasing the dithionite concentration from 2.5-10 Mm, the accumulated P-HBA concentration in 120 min increased from 15.0-27 µM. Whereas, above 10 mM, the p-HBA concentration decreased due to radical scavenging. Increasing soil dosage from 2.5-15 g/100 mL the accumulated p-HBA amount increased from 22.8-33.7 µM. Temperature 25-35 oC and pH 6.2-7.5 were favoured for p-HBA generation. Furthermore, we investigated the roles of different active intermediates in the reaction system and proposed the mechanism behind the ROS genearation. This study suggested that dithionite can be used as an active reagent for advanced oxidation remediation in oxic soil medium.
Assuntos
Estresse Oxidativo , Solo , Solo/química , Ditionita/química , Espécies Reativas de Oxigênio , OxirreduçãoRESUMO
The need to better understand the binding mode of antioxidants (sulfur oxyanions) kinetically is a concern in medicine. Hence, a spectrophotometric method was used to study the application of the Piszkiewicz model on the electron transfer reaction of dithionite ion (S2O42-) and bis-(2-pyridinealdoximato)dioxomolybdate(IV) complex at 303 K and an absorption maxima of 560 nm. It follows an acid dependent reductive pathway that is medium sensitive. Charge distribution from the reaction species contributes to the redox efficiency of the system, resulting in a primary salt effect (NaCl) with an enhanced reaction rate. Alteration of the reaction medium with ethanol led to an elevation of reduction time as the charge catalysis was distorted by a drop in the system permittivity. Likewise, sodium dodecyl sulfate in the system decreased the reduction rate of the complex due to the low impact of hydrophobic and ion interaction between the micelle and substrates. First order reaction kinetics was observed in the concentration of the redox partners and a 2:1 (complex: S2O42-) stoichiometry was obtained with the involvement of hydrogenated sulfite radical which resulted in the formation of sulfur dioxide and a Mo2+ deactivated complex. The occurrence of counterion catalysis is pronounced in the reaction system owing to the participation of like-charged substrates in the rate-controlling phase. The standard enthalpy (69.12 [Formula: see text] 0.05 kJ mol-1) and Gibbs energy (80.10 [Formula: see text] 0.07) kJ mol-1 suggest that the process is endothermic dependent. The investigation of the anionic surfactant effect on the reaction medium was quantitatively ascertained from the Piszkiewicz model of the complex interaction sequence.
Assuntos
Elétrons , Ditionita , Transporte de Elétrons , Oxirredução , Fenômenos Químicos , CinéticaRESUMO
Efforts to estimate the impact of climate change-induced forest expansion on soil carbon stocks in cold regions are hindered by the lack of soil organic carbon (SOC) concentration data. The presented study addressed the information gap by establishing SOC concentration and its variability in two catchments inside the vast, remote, and rugged Putorana Plateau. Additionally, it explored interrelationships among the terrain relief, vegetation cover, surface organic layer, SOC and its mineral association on the northernmost boundary of the forest-tundra biome traversing the northwestern part of the Central Siberian Tableland. Soil samples were taken from the active layer on the slope base, middle, and below the upper forest boundary. Subsequently, they were analyzed for SOC concentration by dry combustion. Multiple linear regression identified associations between slope angle and surface organic layer thickness and between SOC concentration and surface organic layer thickness, clay content, and dithionite-extracted Al. Clay content and surface organic layer thickness explained 68% of the overall SOC concentration variability. When used with data produced by remote sensing-based multipurpose large-scale mapping of selected biophysical factors, the acquired regression equations could aid the estimation of SOC across the rugged terrain of the Siberian Traps.
Assuntos
Carbono , Solo , Argila , Ditionita , Florestas , Minerais , TundraRESUMO
BACKGROUND: NADPH oxidase 1 (Nox1), which is highly expressed in the colon, is thought to play a potential role in host defense as a physical and innate immune barrier against commensal or pathogenic microbes in the gastrointestinal epithelium. Diabetes can be caused by several biological factors, including insulin resistance is one of them. Alloxan is widely used to induce insulin-dependent diabetes in experimental animals. Alloxan increases the generation of reactive oxygen species as a result of metabolic reactions in the body, along with a massive increase in cytosolic calcium concentration. METHODS: Using a universal method, a superoxide radical (Ð2-)-thermostable associate between NADPH-containing lipoprotein (NLP) and NADPH oxidase (Nox)- NLP-Nox was isolated and purified from the small intestine (SI) of control (C) and alloxan-induced diabetic (AD) albino rats. RESULTS: In comparison to the C indices, in AD in the SI, an increase in the specific content of NLP-Nox associate and a decrease in the stationary concentration of produced Ð2- in liquid phase (in solution) and gas phase (during blowing by oxygen of the NLP-Nox solution) were observed. The NLP-Nox of SI associate in C and AD rats produced Ð2- by an immediate mechanism, using NLP as a substrate. The phenomenon of the hiding of the optical absorption maxima of the Nox in oxidized states at pH10,5 was observed in the composition of these SI associates of the C and AD rat groups. The characteristic absorption maxima of the «hidden¼ Nox were observed under these conditions after reduction by potassium dithionite. CONCLUSION: Thus, at AD, the decrease in the stationary concentration of produced Ð2- in the solution and gas phase was compensated for by an increase in the specific amount of associate. In addition, the decrease in the stationary concentration of produced Ð2- by NLP-Nox associates at AD can be linked to a decrease in the level of NADPH in NLP-Nox composition. This could be used as a new mechanism of AD pathogenesis.
Assuntos
Diabetes Mellitus Experimental , Insulinas , Animais , Aloxano , Cálcio , Ditionita , Intestino Delgado/metabolismo , Lipoproteínas , NADP/metabolismo , NADPH Oxidase 1 , NADPH Oxidases/metabolismo , Oxigênio , Potássio , Espécies Reativas de Oxigênio/metabolismo , Superóxidos/metabolismo , RatosRESUMO
In this study, dithionite (DTN) was used to degrade Tetrabromobisphenol A (TBBPA), a widely applied brominated flame retardants, under anaerobic conditions with the reaction terminator of nitrate. The optimization of reaction parameters including TBBPA concentration, DTN concentration and pH value were conducted by response surface methodology (RSM) based on central composite design (CCD). The degradation process could be simulated accurately by a quadratic model with the correlation coefficient R2 of 0.9550. The interaction between pH and DTN concentration was significant with the p-value of 0.0017. Moreover, the maximum TBBPA removal was 87.6 ± 3.2% and obtained at TBBPA concentration of 2.00 µM, the DTN concentration of 322.31 µM, and the pH of 6.14 under anaerobic conditions. It was found that the factors influenced TBBPA removal followed the order: pH > DTN concentration > TBBPA concentration. The major active products from DTN are SO32- and S2O32-. In addition, different inhibitions of natural water matrix including chloride, bicarbonate, sulfide and humic acid on TBBPA degradation had been confirmed. According to the identified six intermediates via gas chromatography-mass spectrometry (GC-MS), two steps of the degradation pathways were speculated, including the breakage of C-Br bond and C-C bond. This study provides a convenient way to degrade TBBPA.
Assuntos
Retardadores de Chama , Bifenil Polibromatos , Anaerobiose , Ditionita , Retardadores de Chama/metabolismo , Bifenil Polibromatos/química , Bifenil Polibromatos/metabolismoRESUMO
Advanced oxidation process (AOPs) is one of the most effective technologies for organic pollutants removal. In this study, diverse reactive species generation and enhanced sulfamethoxazole (SMX) degradation were investigated based on persulfate (PDS) activated by Fe2+&dithionite (DTN). When involving Fe2+&dithionite in PDS, SMX degradation efficiency reached 84 % within 30 min following a pseudo-first-order kinetic, which was higher than those in Fe2+/PDS (50.4 %) and Fe2+/O2/DTN (41.3 %). SO4â¢- and â¢OH were identified as dominant reactive species with a crucial role of FeSO3+ based on quenching experiment and electron spin resonance (ESR). The contributions of SO4·-, ·OH, and other species to SMX degradation were 60.1 %, 33.9 %, and 6 %, respectively. In Fe2+/DTN/PDS system, SMX was effectively degraded under nearly neutral pH (5.0-9.0), with activation energy of 96.04 kJ·mol-1. The experiments and density functional theory (DFT) calculation demonstrated that three functional groups (benzenesulfonamido, benzene ring, and oxazole ring) were attacked for SMX degradation. Moreover, acute toxicity to Vibrio fischeri has enhanced in the earlier degradation process due to the intermediates and weaken with the continuous reaction. This work not only provides a high-activity SO4·--AOP for refractory pollutant treatment with possible dual radical generation resources, but elucidated diverse reactive species formation with Fe2+&dithionite.
Assuntos
Sulfametoxazol , Poluentes Químicos da Água , Teoria da Densidade Funcional , Ditionita , Cinética , Oxirredução , Sulfametoxazol/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidadeRESUMO
Metal-dependent formate dehydrogenases are important enzymes due to their activity of CO2 reduction to formate. The tungsten-containing FdhAB formate dehydrogenase from Desulfovibrio vulgaris Hildenborough is a good example displaying high activity, simple composition, and a notable structural and catalytic robustness. Here, we report the first spectroscopic redox characterization of FdhAB metal centers by EPR. Titration with dithionite or formate leads to reduction of three [4Fe-4S]1+ clusters, and full reduction requires Ti(III)-citrate. The redox potentials of the four [4Fe-4S]1+ centers range between -250 and -530 mV. Two distinct WV signals were detected, WDV and WFV, which differ in only the g2-value. This difference can be explained by small variations in the twist angle of the two pyranopterins, as determined through DFT calculations of model compounds. The redox potential of WVI/V was determined to be -370 mV when reduced by dithionite and -340 mV when reduced by formate. The crystal structure of dithionite-reduced FdhAB was determined at high resolution (1.5 Å), revealing the same structural alterations as reported for the formate-reduced structure. These results corroborate a stable six-ligand W coordination in the catalytic intermediate WV state of FdhAB.
Assuntos
Desulfovibrio vulgaris , Desulfovibrio , Catálise , Desulfovibrio/metabolismo , Desulfovibrio vulgaris/metabolismo , Ditionita , Espectroscopia de Ressonância de Spin Eletrônica , Formiato Desidrogenases/química , Formiato Desidrogenases/metabolismo , Formiatos , Metais , OxirreduçãoRESUMO
Supramolecular materials that respond to external triggers are being extensively utilized in developing spatiotemporal control in biomedical applications ranging from drug delivery to diagnostics. The present article describes the development of self-assembled vesicles in 1:9 (v/v), tetrahydrofuran (THF)-water by naphthalimide-based azo moiety containing amphiphile (NI-Azo) where azo moiety would act as the stimuli-responsive junction. The self-assembly of NI-Azo took place through H-type of aggregation. Microscopic and spectroscopic analyses confirmed the formation of supramolecular vesicles with a dimension of 200-250 nm. Azo (-NâN-) moiety is known to get reduced to amine derivatives in the presence of the azoreductase enzyme, which is overexpressed in the hypoxic microenvironment. The absorbance intensity of this characteristic azo (-NâN-) moiety of NI-Azo (1:9 (v/v), THF-water) at 458 nm got diminished in the presence of both extracellular and intracellular bacterial azoreductase extracted from Escherichia coli bacteria. The same observation was noted in the presence of sodium dithionite (mimic of azoreductase), indicating that azoreductase/sodium dithionite induced azo bond cleavage of NI-Azo, which was confirmed by matrix-assisted laser desorption ionization time-of-flight spectrometric data of the corresponding aromatic amine fragments. The anticancer drug, curcumin, was encapsulated inside NI-Azo vesicles that successfully killed B16F10 cells (cancer cells) in CoCl2-induced hypoxic environment owing to the azoreductase-responsive release of drug. The cancer cell killing efficiency by curcumin-loaded NI-Azo vesicles in the hypoxic condition was 2.15-fold higher than that of the normoxic environment and 2.4-fold higher compared to that of native curcumin in the hypoxic condition. Notably, cancer cell killing efficiency of curcumin-loaded NI-Azo vesicles was 4.5- and 1.9-fold higher than that of noncancerous NIH3T3 cells in normoxic and hypoxic environments, respectively. Cell killing was found to be primarily through the early apoptotic pathway.
Assuntos
Curcumina , Naftalimidas , Aminas , Animais , Compostos Azo/química , Curcumina/farmacologia , Ditionita , Hipóxia , Camundongos , Células NIH 3T3 , ÁguaRESUMO
This work shows a strategy of reducing hexavalent chromium (Cr(VI)) by sodium hyposulfite (Na2S2O3) with self-generated electricity via a dual-chamber non-biological fuel cell (D-nBFC). Therein, Na2S2O3 was electro-oxidized on graphite felt (GF) at anode and Cr(VI) in strong acidic solution was electro-reduced at GF/CCP cathode (GF decorated with conductive carbon paint (CCP)). Additionally, an agar salt bridge, consisting of saturated KCl solution, was introduced to form complete circuit by offering ions. The results showed that Cr(VI) was reduced to trivalent chromium (Cr(III)) and the D-nBFC system could produce electricity in this process. This system could obtain a high Cr(VI) removal efficiency (97.0%), 110 µA maximum current, and 13.4 mW m-2 maximum power density in 4 h. In addition, the proposed system had high reusability after five cycles and the relative standard deviation was only 3.4% (n = 5). Thus, this D-nBFC system provides a promising and eco-friendly method for treatment of Cr(VI) pollution and generating electricity simultaneously, and also has potential application value for other heavy metals remediation.
Assuntos
Fontes de Energia Bioelétrica , Cromo/metabolismo , Ditionita , SódioRESUMO
Angiogenesis caused by acute vascular occlusion occurs in various ischemic diseases. The in vitro tube formation assay by endothelial cells is a rapid, quantitative method for drug discovery on angiogenesis. Tube formation assay on Matrigel has been widely used to identify the angiogenesis, however, there are some problems to limit its application. In this study, we found for the first time that sodium dithionite (SD) could induce endothelial cell tube formation without Matrigel under hypoxia condition. To further verify our findings, the angiogenesis related proteins and mRNA at different time points after tube formation were measured both in primary human large-vessel endothelial cell (HUVECs) and murine microvascular endothelial cell line (Bend.3). In conclusion, compared with traditional tube formation on Matrigel, the novel model exhibits the following advantages: (1) Combination oxygen glucose deprivation with sodium dithionite (OGD-SD) model is operated more easily than traditional tube formation. (2) OGD-SD can be used for not only cell imaging, but also immunofluorescence, protein extraction and gene analysis. (3) OGD-SD is more applicable to acute hypoxia model of endothelial cell in vitro. (4) OGD-SD may be more suitable to identify molecular mechanism of compound that intervenes processes of pro-tube formation, tube formation and tube disconnection.
Assuntos
Células Endoteliais/patologia , Células Endoteliais da Veia Umbilical Humana/patologia , Neovascularização Patológica , Neovascularização Fisiológica , Proteínas Angiogênicas/genética , Proteínas Angiogênicas/metabolismo , Animais , Bioensaio , Hipóxia Celular , Linhagem Celular , Movimento Celular , Ditionita/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Regulação da Expressão Gênica , Glucose/deficiência , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Camundongos , Neovascularização Fisiológica/efeitos dos fármacos , Transdução de SinaisRESUMO
Carbon neutrality has been received more attention and emerged in wastewater treatment processes. Due to the development of treating technologies with the rising of new-emerging pollutants, the coupled chemical processes also should remain current for the goal of carbon-neutral operation. Among of those updated strategies, several advanced oxidation processes (AOPs) based on dithionite (DTN, S2O42-), a common water treatment agent, have been established for refractory organic contaminations removal. However, in terms of DTN detection, the traditional formol-titration method has several application limits including the low detection sensitivity and high consumption of formaldehyde. In this study, compared with traditional method, a low energy consumption technology has been developed based on the potassium ferricyanide with the carbon consumption decreasing by about 5 times. Moreover, detection limit of DTN (mmol/L level) also was lower than the titration method. The method was established based on the fact that every 1 mol of DTN can react with 2 mol [Fe(CN)6]3- under alkaline condition. According to that potassium ferricyanide (K3 [Fe(CN)6]) has the maximum absorption at 419 nm wavelength, a fitting equation based on the linear relationship between the absorbance variation of K3 [Fe(CN)6] and DTN amount in the ranges of 0-30 µmol with the detection limit of 0.6 µmol was established with the determination coefficient of 0.99935. It was found that there was no obvious influence of the ubiquitous foreign species with the amount lower than 6 mM, 4 mM, 6 mM, 4 mM and 1 mg/L for Cl-, HCO3-, NO3-, SO42- and NOM, respectively. Moreover, methanol and tert-butanol were employed to verify the influence of the presence of organic matters on the determination of DTN and no impact was observed in this study. The proposed method provides a new way for DTN detection with stable and countable performance in the related AOPs with the low electric energy and carbon source consumption and high detection efficiency.
Assuntos
Ferricianetos , Tecnologia , Ditionita , Oxirredução , Espectrofotometria/métodosRESUMO
Shale-derived soils have higher clay, organic matter, and secondary Fe oxide content than other bedrock types, all of which can sequester Hg. However, shales also can be Hg-rich due to their marine formation. The objectives of this study were to determine the concentration and phase partitioning of Hg in seven upland weathering profiles from New York to Tennessee USA and use geochemical normalization techniques to estimate the extent of Hg inheritance from weathering of shale bedrock or sequestration of atmospheric Hg. Total Hg concentrations in unweathered shale ranged from 3 to 94 ng/g. Total Hg concentrations decreased with depth in the Ultisols and Alfisols, with total Hg concentrations ranging from 18 to 265 ng/g. Across all shale soils and rocks, the oxidizable fraction of Hg (15% H2O2 extraction) comprised a large portion of the total Hg at 68% ± 8%. This fraction was dominated by organic matter as confirmed with positive correlations between Hg and %LOI, but could also be impacted by Hg sulfides. Across all sites, the reducible fraction of Hg (citrate-bicarbonate-dithionite extraction) was only 10% ± 4% of the total Hg on average. Thus, secondary Fe oxides did not contain a significant portion of Hg, as commonly observed in tropical soils. Although colder sites had a higher organic matter and sequestered more Hg, τ values for Hg indexed to Ti suggest that atmospheric deposition, such as pollution sources in Ohio River Valley, drove the highest enrichment of Hg along the transect. These results demonstrate that shale-derived soils have a net accumulation and retention of atmospheric Hg, primarily through stabilization by organic matter.