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1.
Environ Pollut ; 259: 113801, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31891908

RESUMO

Via the thermal sintering, a nanocrystalline IrO2 coating was formed on the Ti substrate to successfully prepare a Ti/IrO2 electrode. Based on the electrochemical analysis, the prepared Ti/IrO2 electrode was found to have powerful oxidation effect on the organics in the TNT red water, where the nitro compound was oxidized through an irreversible electrochemical process at 0.6 V vs. SCE. According to the analysis of the nitro compound content, the UV-vis spectra, and the FTIR spectra of 2,4,6-trinitrotoluene (TNT) red water with electrolytic periods, the degradation mechanism of the dinitrotoluene sulfonate (DNTS) was developed. And the intermediates were characterized by UPLC-HRMS. The DNTS mainly occurred one electron transfer reaction on the Ti/IrO2 electrode. At the early stage of the electrolysis, the polymerization of DNTS was mainly dominated. The generated polymer did not form a polymer film on the electrode surface, but instead it promoted a further reduction. After electrolyzing for 30 h, all NO2 function group in the TNT red water was degraded completely.


Assuntos
Trinitrotolueno/química , Poluentes Químicos da Água/química , Eletrodos , Irídio/química , Oxirredução , Titânio , Eliminação de Resíduos Líquidos , Água
2.
PLoS One ; 14(10): e0224112, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31639172

RESUMO

Photolysis is one of the main transformation pathways for 2,4,6-trinitrotoluene (TNT) released into the environment. Upon exposure to sunlight, TNT is known to undergo both oxidation and reduction reactions with release of nitrite, nitrate, and ammonium ions, followed by condensation reactions of the oxidation and reduction products. In this study, compound classes of transformation products from the aqueous and solid phase photodegradation of 2,4,6-trinitrotoluene (TNT) have been identified by liquid and solid state 13C and 15N NMR. Aqueous phase experiments were performed on saturated solutions of T15NT in deionized water, natural pond water (pH = 8.3, DOC = 3.0 mg/L), pH 8.0 buffer solution, and in the presence of Suwannee River Natural Organic Matter (SRNOM; pH = 3.7), using a Pyrex-filtered medium pressure mercury lamp. Natural sunlight irradiations were performed on TNT in the solid phase and dissolved in the pond water. In deionized water, carboxylic acid, aldehyde, aromatic amine, primary amide, azoxy, nitrosophenol, and azo compounds were formed. 15N NMR spectra exhibited major peaks centered at 128 to 138 ppm, which are in the range of phenylhydroxylamine and secondary amide nitrogens. The secondary amides are proposed to represent benzanilides, which would arise from photochemical rearrangement of nitrones formed from the condensation of benzaldehyde and phenylhydroxylamine derivatives of TNT. The same compound classes were formed from sunlight irradiation of TNT in the solid phase. Whereas carboxylic acids, aldehydes, aromatic amines, phenylhydroxylamines, and amides were also formed from irradiation of TNT in pond water and in pH 8 buffer solution, azoxy and azo compound formation was inhibited. Solid state 15N NMR spectra of photolysates from the lamp irradiation of unlabeled 2,6-dinitrotoluene in deionized water also demonstrated the formation of aromatic amine, phenylhydroxylamine/ 2° amide, azoxy, and azo nitrogens.


Assuntos
Isótopos de Carbono/análise , Espectroscopia de Ressonância Magnética/métodos , Isótopos de Nitrogênio/análise , Fotólise/efeitos da radiação , Rios/química , Trinitrotolueno/metabolismo , Água/análise , Luz Solar , Trinitrotolueno/química , Trinitrotolueno/efeitos da radiação
3.
Molecules ; 24(10)2019 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-31108849

RESUMO

Kinetic thermal analysis was conducted using in situ atomic force microscopy (AFM) at a temperature range of 15-25 °C to calculate the activation energy of the sublimation of 2,4,6-trinitrotoluene (TNT) islands. The decay of different diameter ranges (600-1600 nm) of TNT islands was imaged at various temperatures isothermally such that an activation energy could be obtained. The activation energy of the sublimation of TNT increases as the diameter of islands increases. It was found that the coarsening and the sublimation rate of TNT islands can be determined by the local environment of the TNT surface. This result demonstrates that a diffusion model cannot be simply applied to "real world" systems for explaining the sublimation behavior and for estimating the coarsening of TNT.


Assuntos
Substâncias Explosivas/química , Trinitrotolueno/química , Cinética , Microscopia de Força Atômica , Temperatura
4.
Org Biomol Chem ; 17(23): 5666-5670, 2019 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-30973549

RESUMO

Selective and sensitive detection of desired targets is very critical in sensor design. Here, we report a genetically engineered M13 bacteriophage-based sensor system evaluated by quantum mechanics (QM) calculations. Phage display is a facile way to develop the desired peptide sequences, but the resulting sequences can be imperfect peptides for binding of target molecules. A TNT binding peptide (WHW) carrying phage was self-assembled to fabricate thin films and tested for the sensitive and selective surface plasmon resonance-based detection of TNT molecules at the 500 femtomole level. SPR studies performed with the WHW peptide and control peptides (WAW, WHA, AHW) were well-matched with those of the QM calculations. Our combined method between phage engineering and QM calculation will significantly enhance our ability to design selective and sensitive sensors.


Assuntos
Bacteriófago M13/genética , Engenharia Genética , Trinitrotolueno/química , Regulação Viral da Expressão Gênica , Conformação Proteica , Teoria Quântica , Trinitrotolueno/metabolismo , Proteínas Virais
5.
Molecules ; 24(6)2019 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-30909608

RESUMO

Non-isothermal sublimation kinetics of low-volatile materials is more favorable over isothermal data when time is a crucial factor to be considered, especially in the subject of detecting explosives. In this article, we report on the in-situ measurements of the sublimation activation energy for 2,4,6-trinitrotoluene (TNT) continuous nanofilms in air using rising-temperature UV-Vis absorbance spectroscopy at different heating rates. The TNT films were prepared by the spin coating deposition technique. For the first time, the most widely used procedure to determine sublimation rates using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) was followed in this work using UV-Vis absorbance spectroscopy. The sublimation kinetics were analyzed using three well-established calculating techniques. The non-isothermal based activation energy values using the Ozawa, Flynn⁻Wall, and Kissinger models were 105.9 ± 1.4 kJ mol-1, 102.1 ± 2.7 kJ mol-1, and 105.8 ± 1.6 kJ mol-1, respectively. The calculated activation energy agreed well with our previously reported isothermally-measured value for TNT nanofilms using UV-Vis absorbance spectroscopy. The results show that the well-established non-isothermal analytical techniques can be successfully applied at a nanoscale to determine sublimation kinetics using absorbance spectroscopy.


Assuntos
Substâncias Explosivas/química , Calefação , Trinitrotolueno/química , Varredura Diferencial de Calorimetria , Substâncias Explosivas/isolamento & purificação , Cinética , Análise Espectral , Temperatura , Termogravimetria/métodos , Trinitrotolueno/isolamento & purificação
6.
J Colloid Interface Sci ; 544: 206-216, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30849618

RESUMO

Palladium (Pd)-catalyzed reactions mostly show structure sensitivity: i.e., the selectivity and activity of the reactions are highly dependent on the arrangement of Pd atoms. In this regard, branched Pd nanoparticles show enhanced catalytic performance owing to the presence of low coordinated Pd atoms. In this paper, a novel solution-phase synthesis of flower-like Pd nanodendrites using ribonucleic acid (RNA) as a capping agent and ascorbic acid as a reducing agent was described. On the other hand, the co-use of polyvinylpyrrolidone (PVP) and potassium bromide (KBr) instead of RNA at the same synthesis conditions led to cuboid nanoparticles, while the sole use of ascorbic acid resulted in faceted nanoparticles. The formation of nanodendritic morphology was attributed to the RNA-assisted growth through particle attachment. This scenario was supported by TEM analysis that demonstrated the aggregation of small particles to form larger nanoparticles at the onset of the reaction. The shape and size of the nanoparticles could be readily tuned by the RNA content used. XPS confirmed the formation of metallic Pd nanoparticles. The presence of crystalline planes of {1 1 1}, {2 0 0}, {2 2 0}, {3 1 1} and {2 2 2} was demonstrated by XRD and SAED analyses. The Pd nanodendrites were used for the reduction of p-nitrophenol (PNP) and 2,4,6-trinitrotoluene (TNT), and reduction rate constants (k) were calculated as 1.078 min-1 (normalized rate constant, knor = 59.66 mmol-1 s-1) for PNP and 0.3181 min-1 (knor = 17.6 mmol-1 s-1) for TNT with the corresponding turnover frequencies (TOFs) as 16.06 and 40.80 h-1, respectively.


Assuntos
Dendritos/química , Nanopartículas Metálicas/química , Nanopartículas/química , Paládio/química , Brometos/química , Catálise , Cinética , Nitrofenóis/química , Oxirredução , Tamanho da Partícula , Compostos de Potássio/química , Povidona/química , RNA/química , Propriedades de Superfície , Trinitrotolueno/química
7.
Phys Chem Chem Phys ; 21(22): 11589-11598, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-30801593

RESUMO

Biodegradation is a cost-effective and environmentally friendly alternative to removing 2,4,6-trinitrotoluene (TNT) pollution. However, mechanisms of TNT biodegradation have been elusive. To enhance the understanding of TNT biotransformation by the Old Yellow Enzyme (OYE) family, we investigated the crucial first-step hydrogen-transfer reaction by molecular dynamics simulations, docking technologies and empirical valence bond calculations. We revealed the significance of the π-π stacking conformation between the substrate TNT and the reduced flavin mononucleotide (FMNH2) cofactor, which is a prerequisite for the aromatic ring reduction of TNT. Under the π-π stacking conformation, the barrier of the hydrogen-transfer reaction in the aromatic ring reduction is about 16 kcal mol-1 lower than that of nitro group reduction. Then, we confirmed the mechanism of controlling the π-π stacking, that is, the π-π interaction competition mechanism. It indicates that the π-π stacking of TNT and FMNH2 occurs only when the π-π interaction between FMNH2 and TNT is stronger than that between TNT and several key residues with aromatic rings. Finally, based on the competition mechanism, the formation of π-π stacking of TNT and FMNH2 can be successfully enabled by removing the aromatic ring of those key residues in enzymes that originally only transform TNT through the nitro group reduction. This testified the validity of the π-π interaction competition mechanism. This work theoretically clarifies the molecular mechanism of the first-step hydrogen-transfer reaction for the biotransformation of TNT by the OYE family. It is helpful to obtain the enzymes that can biodegrade TNT through the aromatic ring reduction.


Assuntos
Flavoproteínas/metabolismo , NADPH Desidrogenase/metabolismo , Trinitrotolueno/metabolismo , Animais , Bactérias/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Biotransformação , Domínio Catalítico , Mononucleotídeo de Flavina/química , Flavoproteínas/química , Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Himenópteros/enzimologia , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Modelos Químicos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , NADPH Desidrogenase/química , Oxirredução , Ligação Proteica , Saccharomyces/enzimologia , Eletricidade Estática , Trinitrotolueno/química
8.
Biosens Bioelectron ; 126: 590-595, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30500774

RESUMO

A new immunoassay format using thermally induced defragmentation of some nitro-explosives with a high degree of selectivity is reported. Specific antibodies against three widely used explosives, 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and pentaerythritol tetranitrate (PETN) were generated by designing suitable haptens using geometry optimization modules. These in-house generated antibodies were used in a newly developed thermal mediated immunochemical biosensing technique which involves the binding of specific antibodies to respective nitro-explosives on a microtiter strip, resulting in the formation of specific immunocomplex. Heating the specific immuno-complex formed on microtiter wells resulted in thermal lysis of nitro-explosives to generate nitrite ions. These ions react with Griess reagent to form a colored chromophore which correlates the concentration of individual explosive in the sample. The present work fulfills the need for an improved explosive detecting system that is highly specific and capable of quickly determining the presence of nitrate containing explosives from a mixture pool.


Assuntos
Técnicas Biossensoriais , Substâncias Explosivas/isolamento & purificação , Triazinas/isolamento & purificação , Trinitrotolueno/isolamento & purificação , Anticorpos/química , Substâncias Explosivas/química , Haptenos/química , Haptenos/imunologia , Temperatura , Triazinas/química , Triazinas/imunologia , Trinitrotolueno/química , Trinitrotolueno/imunologia
9.
Anal Chem ; 90(24): 14469-14474, 2018 12 18.
Artigo em Inglês | MEDLINE | ID: mdl-30458612

RESUMO

Accurate, sensitive, and selective detection of explosives is of vital importance in antiterrorism and homeland security. Fluorescence sensors are prevalent for sensitive and fast in-field explosive detection but are sometimes compromised by accuracy and stability due to the similar structures of explosives, photobleaching, and complex sample matrixes. Herein, we developed a first bimodal methodology capable of both sensitive in-field fluorescence detection and accurate laboratory mass spectrometric quantification of 2,4,6-trinitrotoluene (TNT) by utilizing the characteristic fluorescent and mass spectrometric response of copper nanoparticles (CuNPs). An excellent selectivity was also realized by involving aptamer recognition. The methodology is capable of detecting TNT at subpart per trillion (PPT) levels, with a detection limit of 0.32 pg mL-1 by inductively coupled plasma mass spectrometry (ICPMS) and 0.17 ng mL-1 by fluorimetry. The signal response was accurate and stable for at least 60 days by ICPMS. Thanks to the biospecificity of the aptamer, this bimodal methodology is potentially applicable to a large panel of explosives.


Assuntos
Cobre/química , Limite de Detecção , Nanopartículas Metálicas/química , Polímeros/química , Timina/química , Trinitrotolueno/análise , Espectrometria de Fluorescência , Trinitrotolueno/química
10.
Chemosphere ; 197: 603-610, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29407823

RESUMO

This study investigates the fate of sorbed nitroaromatics on the surface of pyrogenic carbonaceous matter (PCM) to assess the feasibility of a PCM-promoted hydrolysis. The degradation of two nitroaromatic compounds, 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole, was observed at pH 7 in the presence of graphite powder, a model PCM. By contrast, no decay occurred without graphite. Using TNT as a model compound, our results suggest that TNT decay demonstrated a strong pH dependence, with no reaction at pH 3-5 but rapid degradation at pH 6-10. Moreover, by fitting TNT decay at different pH conditions along with its sorption kinetics to the Langmuir Kinetic Model, our results suggest that the base-catalyzed hydrolysis was important. The activation energy for TNT decay was obtained by measuring reaction rates at different temperatures with or without graphite and no significant difference was observed. However, the addition of tetramethylammonium cation was able to promote TNT decay possibly due to its ability to attract more OH- from the aqueous solution, leading to an increase in the sorbed OH- concentrations. Nitrite and a Meisenheimer complex were identified as degradation products for TNT. Other PCM, such as biochar, also demonstrated a comparable ability in promoting TNT decay at pH 7. Furthermore, a rapid degradation of TNT at pH 7 was observed when biochar was used as a soil amendment (4% by weight). Our results suggest that PCM can facilitate TNT and 2,4-dinitroanisole decay via a surface-promoted hydrolysis at neutral pH conditions, suggesting a promising alternative for in situ soil remediation.


Assuntos
Anisóis/química , Modelos Químicos , Poluentes do Solo/química , Trinitrotolueno/química , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Solo , Poluentes do Solo/análise , Água
11.
PLoS One ; 12(12): e0189177, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29281650

RESUMO

Explosives are a common soil contaminant at a range of sites, including explosives manufacturing plants and areas associated with landmine detonations. As many explosives are toxic and may cause adverse environmental effects, a large body of research has targeted the remediation of explosives residues in soil. Studies in this area have largely involved spiking 'pristine' soils using explosives solutions. Here we investigate the fate of explosives present in soils following an actual detonation process and compare this to the fate of explosives spiked into 'pristine' undetonated soils. We also assess the effects of the detonations on the physical properties of the soils. Our scanning electron microscopy analyses reveal that detonations result in newly-fractured planes within the soil aggregates, and novel micro Computed Tomography analyses of the soils reveal, for the first time, the effect of the detonations on the internal architecture of the soils. We demonstrate that detonations cause an increase in soil porosity, and this correlates to an increased rate of TNT transformation and loss within the detonated soils, compared to spiked pristine soils. We propose that this increased TNT transformation is due to an increased bioavailability of the TNT within the now more porous post-detonation soils, making the TNT more easily accessible by soil-borne bacteria for potential biodegradation. This new discovery potentially exposes novel remediation methods for explosive contaminated soils where actual detonation of the soil significantly promotes subsequent TNT degradation. This work also suggests previously unexplored ramifications associated with high energy soil disruption.


Assuntos
Substâncias Explosivas , Poluentes do Solo/análise , Trinitrotolueno/química , Bactérias/metabolismo , Disponibilidade Biológica , Microscopia Eletrônica de Varredura , Porosidade , Microbiologia do Solo , Trinitrotolueno/análise , Trinitrotolueno/metabolismo , Microtomografia por Raio-X
12.
J Environ Qual ; 46(5): 968-974, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28991974

RESUMO

High explosives (HEs) deposited on military ranges can leach through the soil and contaminate groundwater. We examined the transport and fate of HEs in laboratory columns containing soils from two hand grenade bays (Bays C and T) and the impact of organic amendments on biodegradation. Soil characteristics were similar; however, Bay C had somewhat higher clay and organic C. Experimental treatments included addition of crude glycerin and lignosulfonate, and parallel control columns. Experimental results showed extensive 2,4,6-trinitrotoluene (TNT) degradation with minimal leaching, consistent with prior batch microcosm results. Amendment addition enhanced TNT degradation in both Bays C and T compared with controls. Although hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive, or RDX) did not biodegrade in prior aerobic batch microcosms, 64 to 77% of RDX biodegraded in untreated soil columns with O present in the mobile soil gas. The RDX biodegradation was likely associated with short-term anoxic conditions or anoxic micro-niches. In nearly saturated Bay C columns, RDX removal increased to >92%. Amendment addition to unsaturated Bay T columns increased RDX removal to >86%. In one column, the soil remained anoxic (O < 5% by volume) for about a year after amendment addition, significantly reducing RDX leaching. Nitroso degradation products were produced equivalent to 9 to 39% of the RDX degraded, with most retained in the soil (9-37%) and 0 to 3% in the effluent. These results demonstrate that RDX biodegradation can occur in soils with measurable O, and that amendment addition can reduce RDX leaching by stimulating anaerobic biodegradation.


Assuntos
Biodegradação Ambiental , Substâncias Explosivas/metabolismo , Triazinas/metabolismo , Trinitrotolueno/metabolismo , Substâncias Explosivas/química , Solo , Microbiologia do Solo , Poluentes do Solo , Triazinas/química , Trinitrotolueno/química
13.
J Environ Qual ; 46(5): 961-967, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28991983

RESUMO

2,4,6-Trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive, or RDX) deposited on hand grenade training ranges can leach through the soil and impact shallow groundwater. A 27-mo field monitoring project was conducted to evaluate the transport and attenuation of high explosives in variably saturated soils at an active grenade range located at Fort Bragg, NC. Two approaches were evaluated: (i) natural attenuation in grenade Bay C; and (ii) enhanced attenuation in Grenade Bay T. There was no evidence of TNT accumulation or leaching in surface soils or pore water in either bay, consistent with parallel laboratory studies showing aerobic and anaerobic biodegradation of TNT. In the untreated Bay C, the low saturated hydraulic conductivity () combined with high rainfall and warm summer temperatures resulted in reducing conditions (low oxidation-reduction potential), an increase in dissolved Mn, and a rapid decline in nitrate and RDX. In Bay T, the somewhat greater and lower soil organic C level resulted in more oxidizing conditions with greater RDX leaching. A single-spray application of glycerin and lignosulfonate to the soil surface in Bay T was effective in generating reducing conditions and stimulating RDX biodegradation for ∼1 yr.


Assuntos
Biodegradação Ambiental , Substâncias Explosivas/química , Triazinas/química , Trinitrotolueno/química , Solo , Poluentes do Solo , Temperatura
14.
J Agric Food Chem ; 65(44): 9807-9814, 2017 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-29068213

RESUMO

In this work, we developed a simple and sensitive ratiometric fluorescent assay for sensing trinitrotoluene (TNT) based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent nanoparticles (RFNs), which was designed by hybridizing green emissive carbon dots (CDs) and red emissive quantum dots (QDs) into a silica sphere as a fluorophore pair. AuNPs in their dispersion state can be a powerful absorber to quench CDs, while the aggregated AuNPs can quench QDs in the IFE-based fluorescent assays as a result of complementary overlap between the absorption spectrum of AuNPs and emission spectrum of RFNs. As a result of the fact that TNT can induce the aggregation of AuNPs, with the addition of TNT, the fluorescent of QDs can be quenched, while the fluorescent of CDs would be recovered. Then, ratiometric fluorescent detection of TNT is feasible. The present IFE-based ratiometric fluorescent sensor can detect TNT ranging from 0.1 to 270 nM, with a detection limit of 0.029 nM. In addition, the developed method was successfully applied to investigate TNT in water and soil samples with satisfactory recoveries ranging from 95 to 103%, with precision below 4.5%. The simple sensing approach proposed here could improve the sensitivity of colorimetric analysis by changing the ultraviolet analysis to ratiometric fluorescent analysis and promote the development of a dual-mode detection system.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Espectrometria de Fluorescência/métodos , Trinitrotolueno/química , Fluorescência , Limite de Detecção , Pontos Quânticos/química
15.
Molecules ; 22(8)2017 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-28805729

RESUMO

Microbial remediation of nitroaromatic compounds (NACs) is a promising environmentally friendly and cost-effective approach to the removal of these life-threating agents. Escherichia coli (E. coli) has shown remarkable capability for the biotransformation of 2,4,6-trinitro-toluene (TNT). Efforts to develop E. coli as an efficient TNT degrading biocatalyst will benefit from holistic flux-level description of interactions between multiple TNT transforming pathways operating in the strain. To gain such an insight, we extended the genome-scale constraint-based model of E. coli to account for a curated version of major TNT transformation pathways known or evidently hypothesized to be active in E. coli in present of TNT. Using constraint-based analysis (CBA) methods, we then performed several series of in silico experiments to elucidate the contribution of these pathways individually or in combination to the E. coli TNT transformation capacity. Results of our analyses were validated by replicating several experimentally observed TNT degradation phenotypes in E. coli cultures. We further used the extended model to explore the influence of process parameters, including aeration regime, TNT concentration, cell density, and carbon source on TNT degradation efficiency. We also conducted an in silico metabolic engineering study to design a series of E. coli mutants capable of degrading TNT at higher yield compared with the wild-type strain. Our study, therefore, extends the application of CBA to bioremediation of nitroaromatics and demonstrates the usefulness of this approach to inform bioremediation research.


Assuntos
Engenharia Metabólica/métodos , Trinitrotolueno/química , Trinitrotolueno/metabolismo , Biodegradação Ambiental , Biotransformação , Catálise , Técnicas de Cultura de Células , Escherichia coli , Cinética , Modelos Biológicos , Fenótipo , Biologia de Sistemas
16.
ACS Comb Sci ; 19(10): 625-632, 2017 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-28845964

RESUMO

Complementarity-determining regions (CDRs) are sites on the variable chains of antibodies responsible for binding to specific antigens. In this study, a short peptide probe for recognition of 2,4,6-trinitrotoluene (TNT), was identified by testing sequences derived from the CDRs of an anti-TNT monoclonal antibody. The major TNT-binding site in this antibody was identified in the heavy chain CDR3 by antigen docking simulation and confirmed by an immunoassay using a spot-synthesis based peptide array comprising amino acid sequences of six CDRs in the variable region. A peptide derived from heavy chain CDR3 (RGYSSFIYWF) bound to TNT with a dissociation constant of 1.3 µM measured by surface plasmon resonance. Substitution of selected amino acids with basic residues increased TNT binding while substitution with acidic amino acids decreased affinity, an isoleucine to arginine change showed the greatest improvement of 1.8-fold. The ability to create simple peptide binders of volatile organic compounds from sequence information provided by the immune system in the creation of an immune response will be beneficial for sensor developments in the future.


Assuntos
Anticorpos Monoclonais/química , Peptídeos/química , Trinitrotolueno/química , Sequência de Aminoácidos , Sítios de Ligação , Regiões Determinantes de Complementaridade , Humanos , Imunoensaio , Ligação Proteica , Sensibilidade e Especificidade , Ressonância de Plasmônio de Superfície , Trinitrotolueno/imunologia
17.
Chemosphere ; 184: 438-451, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28618276

RESUMO

Explosive materials are energetic substances, when released into the environment, contaminate by posing toxic hazards to environment and biota. Throughout the world, soils are contaminated by such contaminants either due to manufacturing operations, military activities, conflicts of different levels, open burning/open detonation (OB/OD), dumping of munitions etc. Among different forms of chemical explosives, 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocine (HMX) are most common. These explosives are highly toxic as USEPA has recommended restrictions for lifetime contact through drinking water. Although, there are several utilitarian aspects in anthropogenic activities, however, effective remediation of explosives is very important. This review article emphasizes the details of appropriate practices to ameliorate the contamination. Critical evaluation has also been made to encompass the recent knowledge and advancement about bioremediation and phytoremediation of explosives (especially TNT, RDX and HMX) along with the molecular mechanisms of biodegradation.


Assuntos
Biodegradação Ambiental , Substâncias Explosivas/química , Azocinas/química , Poluentes do Solo , Triazinas/química , Trinitrotolueno/química
19.
Water Sci Technol ; 75(3-4): 716-726, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-28192365

RESUMO

Silica nanoparticles with a surface area of 673.60 m2/g and particle size of 8-12 nm were prepared using aerogel process (AP) followed by super critical drying. Zero valent Fe, Co, Pt, and bimetallic Fe/Pt and Fe/Co were loaded using an incipient wetness impregnation technique and subsequent reduction. Scanning electron microscopy-energy dispersive X-ray (SEM-EDX) and transmission electron microscopy-energy dispersive X-ray (TEM-EDX) characterizations indicated fine dispersion of iron on AP-SiO2 +Fe system. Prepared nanoparticles were evaluated for the adsorptive removal of 2,4,6-trinitrotoluene (TNT) from water. Surface area normalized rate constant values indicated the adsorptive removal potential of prepared nanoparticles to be: AP-SiO2 + Fe/Co > AP-SiO2 + Fe > CM (commercial) SiO2 + Fe > AP-SiO2 + Co > AP-SiO2 + Fe/Pt > AP-SiO2 + Pt. Lower pH helped in accelerating the reactive removal of TNT on zero valent iron loaded silica. AP-SiO2 + Fe/Co system showed the maximum adsorption potential (74 mg/g) after five cycles.


Assuntos
Nanopartículas Metálicas/química , Dióxido de Silício/química , Trinitrotolueno/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Propriedades de Superfície , Trinitrotolueno/química , Poluentes Químicos da Água/química
20.
Environ Toxicol Chem ; 36(5): 1170-1180, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-27791286

RESUMO

The lack of knowledge on the fate of explosive compounds 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), particularly in marine ecosystems, constrains the application of bioremediation techniques in explosive-contaminated coastal sites. The authors present a comparative study on anaerobic biodegradation and mineralization of 15 N-nitro group isotopically labeled TNT and RDX in organic carbon-rich, fine-grained marine sediment with native microbial assemblages. Separate sediment slurry experiments were carried out for TNT and RDX at 23°C for 16 d. Dissolved and sediment-sorbed fractions of parent and transformation products, isotopic compositions of sediment, and mineralization products of the dissolved inorganic N pool (15 NH4+ ,15 NO3- ,15 NO2- , and 15 N2 ) were measured. The rate of TNT removal from the aqueous phase was faster (0.75 h-1 ) than that of RDX (0.37 h-1 ), and 15 N accumulation in sediment was higher in the TNT (13%) than the RDX (2%) microcosms. Mono-amino-dinitrotoluenes were identified as intermediate biodegradation products of TNT. Two percent of the total spiked TNT-N is mineralized to dissolved inorganic N through 2 different pathways: denitration as well as deamination and formation of NH4+ , facilitated by iron and sulfate reducing bacteria in the sediments. The majority of the spiked TNT-N (85%) is in unidentified pools by day 16. Hexahydro-1,3,5-trinitro-1,3,5-triazine (10%) biodegrades to nitroso derivatives, whereas 13% of RDX-N in nitro groups is mineralized to dissolved inorganic N anaerobically by the end of the experiment. The primary identified mineralization end product of RDX (40%) is NH4+ , generated through either deamination or mono-denitration, followed by ring breakdown. A reasonable production of N2 gas (13%) was seen in the RDX system but not in the TNT system. Sixty-eight percent of the total spiked RDX-N is in an unidentified pool by day 16 and may include unquantified mineralization products dissolved in water. Environ Toxicol Chem 2017;36:1170-1180. © 2016 SETAC.


Assuntos
Substâncias Explosivas/metabolismo , Sedimentos Geológicos/química , Triazinas/metabolismo , Trinitrotolueno/metabolismo , Biodegradação Ambiental , Substâncias Explosivas/química , Marcação por Isótopo , Isótopos de Nitrogênio/química , Análise de Componente Principal , Triazinas/química , Trinitrotolueno/química , Água/química
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