PEGylated anticancer-carbon nanotubes complex targeting mitochondria of lung cancer cells

Although activating apoptosis in cancer cells by targeting the mitochondria is an effective strategy for cancer therapy, insufficient targeting of the mitochondria in cancer cells restricts the availability in clinical treatment. Here, we report on a polyethylene glycol-coated carbon nanotube (CNT)-ABT737 nanodrug that improves the mitochondrial targeting of lung cancer cells. The polyethylene glycol-coated CNT-ABT737 nanodrug internalized into the early endosomes via macropinocytosis and clathrin-mediated endocytosis in advance of early endosomal escape and delivered into the mitochondria. Cytosol release of the nanodrug led to apoptosis of lung cancer cells by abruption of the mitochondrial membrane potential, inducing Bcl-2-mediated apoptosis and generating intracellular reactive oxygen species. As such, this study provides an effective strategy for increasing the anti-lung cancer efficacy by increasing mitochondria accumulation rate of cytosol released anticancer nanodrugs.

Tailoring the properties of a zero-valent iron-based composite by mechanochemistry for nitrophenols degradation in wastewaters

Zero-valent iron (ZVI) is a valuable material for environmental remediation, because of its safeness, large availability, and inexpensiveness. Moreover, its reactivity can be improved by addition of (nano-) particles of other elements such as noble metals. However, common preparation methods for this kind of iron-based composites involve wet precipitation of noble metal salt precursors, so they are often expensive and not green. Mechanochemical procedures can provide a solvent-free alternative, even at a large scale. The present study demonstrates that it is possible to tailor functional properties of ZVI-based materials, utilizing high-energy ball milling. All main preparation parameters are investigated and discussed. Specifically, a copper-carbon-iron ternary composite was prepared for fast degradation of 4-nitrophenol (utilized as model pollutant) to 4-aminophenol and other phenolic compounds. Copper and carbon are purposely chosen to insert specific properties to the composite: Copper acts as efficient nano-cathode that enhances electron transfer from iron to 4-nitrophenol, while carbon protects the iron surface from fast oxidation in open air. In this way, the reactive material can rapidly reduce high concentration of nitrophenols in water, it does not require acid washing to be activated, and can be stored in open air for one week without any significant activity loss.

Exploring the mechanism and kinetics of Fe-Cu-Ag trimetallic particles for p-nitrophenol reduction

Preparation conditions of Fe-Cu-Ag trimetallic particles were optimized by single-factor and response surface methodology (RSM) batch experiments to obtain high-reactive Fe⁰-based materials for p-nitrophenol (PNP) removal. Under the optimal conditions (i.e., Fe⁰ dosage of 34.86 g L^-1, theoretical Cu mass loading of 81.87 mg Cu/g Fe, theoretical Ag mass loading of 1.15 mg Ag/g Fe, and preparation temperature of 52.1 °C), the actual rate constant (k_obs) of PNP reduction in 5 min was 1.64 min^-1, which shows a good agreement between the model prediction (1.85 min^-1) of RSM and the experimental data. Furthermore, the high reactivity of Fe⁰-based trimetals was mainly attributed to the plating order of transition metals (i.e., Ag and Cu). Furthermore, we propose a new theory that the pyramid trimetallic structure of Fe-Cu-Ag could improve the electron transport and create active sites with high electron density at the surface (Ag layer) that could enhance the generation of surface-bonded atomic hydrogen ([H]_abs) or the direct reduction of pollutant. Moreover, Fe-Cu-Ag trimetallic particles were characterized by SEM, EDS, and XPS, which also could confirm the proposed theory. In addition, the leached Cu²⁺(<10 μg L^-1) and Ag⁺ (below detection limits) in Fe-Cu-Ag system could be neglected completely, which suggests that Fe-Cu-Ag is reliable, safe, and environment friendly. Therefore, Fe-Cu-Ag trimetallic system would be promising for the removal of pollutants from industrial wastewater.

One-step in situ hydrothermal fabrication of octahedral CdS/SnIn4S8 nano-heterojunction for highly efficient photocatalytic treatment of nitrophenol and real pharmaceutical wastewater

Octahedral CdS/SnIn₄S₈ nano-heterojunctions were fabricated by a facile and simple one-step in situ hydrothermal method, and the molar ratio of CdS to SnIn₄S₈ was optimized. The optimal (0.5:1)CdS/SnIn₄S₈ heterojunctions exhibit the highest visible-light photocatalytic activity with 97.1% degradation efficiency of 2-nitrophenol in 120min, which is much higher than those of individual CdS and SnIn₄S₈. The enhanced photocatalytic performance could be attributed to the effective separation and transfer of photogenerated charges originating from the well-matched band gap structures. Of special significance is that (0.5:1)CdS/SnIn₄S₈ can effectively mineralize 2-nitrophenol and real pharmaceutical wastewater. Moreover, CdS/SnIn₄S₈ nano-heterojunctions show excellent reusability in five cycles due to the stable surface composition and chemical valence state.

The role of nitrite in sulfate radical-based degradation of phenolic compounds: An unexpected nitration process relevant to groundwater remediation by in-situ chemical oxidation (ISCO)

As promising in-situ chemical oxidation (ISCO) technologies, sulfate radical-based advanced oxidation processes (SR-AOPs) are applied in wastewater treatment and groundwater remediation in recent years. In this contribution, we report for the first time that, thermally activated persulfate oxidation of phenol in the presence of nitrite (NO₂^-), an anion widely present in natural waters, could lead to the formation of nitrated by-products including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,6-dinitrophenol (2,6-DNP). Nitrogen dioxide radical (NO₂^•), arising from SO₄^•- scavenging by NO₂^-, was proposed to be involved in the formation of nitrophenols as a nitrating agent. It was observed that nitrophenols accounted for approximately 70% of the phenol transformed under reaction conditions of [NO₂^-] = 200 μM, [PS] = 2 mM and temperature of 50 °C. Increasing the concentration of NO₂^- remarkably enhanced the formation of nitrophenols but did not affect the transformation rate of phenol significantly. The degradation of phenol and the formation of nitrophenols were significantly influenced by persulfate dosage, solution pH and natural organic matter (NOM). Further studies on the degradation of other phenolic compounds, including 4-chlorophenol (4-CP), 4-hydroxybenzoic acid (4-HBA), and acetaminophen (ATP), verified the formation of their corresponding nitrated by-products as well. Therefore, formation of nitrated by-products is probably a common but overlooked phenomenon during SO₄^•--based oxidation of phenolic compounds in the presence of NO₂^-. Nitroaromatic compounds are well known for their carcinogenicity, mutagenicity and genotoxicity, and are potentially persistent in the environment. The formation of nitrated organic by-products in SR-AOPs should be carefully scrutinized, and risk assessment should be carried out to assess possible health and ecological impacts.

p-Nitrophenol degradation by electro-Fenton process: Pathway, kinetic model and optimization using central composite design

The chemical process scale-up, from lab studies to industrial production, is challenging and requires deep knowledge of the kinetic model and the reactions that take place in the system. This knowledge is also useful in order to be employed for the reactor design and the determination of the optimal operational conditions. In this study, a model substituted phenol such as p-nitrophenol was degraded by electro-Fenton process and the reaction products yielded along the treatment were recorded. The kinetic model was developed using Matlab software and was based on main reactions that occurred until total mineralization which allowed predicting the degradation pathway under this advanced oxidation process. The predicted concentration profiles of p-nitrophenol, their intermediates and by-products in electro-Fenton process were validated with experimental assays and the results were consistent. Finally, based on the developed kinetic model the degradation process was optimized using central composite design taking as key parameters the ferrous ion concentration and current density.

Effects of water pH on the uptake and elimination of the piscicide, 3-trifluoromethyl-4-nitrophenol (TFM), by larval sea lamprey

Invasive sea lamprey (Petromyzon marinus) populations in the Great Lakes are controlled by applying the piscicide, 3-trifluoromethyl-4-nitrophenol (TFM), to infested streams with larval sea lamprey (ammocoetes). While treatment mortality is >90%, surviving lamprey, called residuals, can undermine control efforts. A key determinant of TFM effectiveness is water pH, which can fluctuate daily and seasonally in surface waters. The objectives of this research were to evaluate the influence of pH on the uptake, elimination, and accumulation of TFM by larval sea lamprey using radio-labeled TFM (¹⁴C-TFM), when exposed to a nominal concentration of 4.6mgTFML^-1 or 7.6mgTFML^-1, 3h or 1h, respectively. TFM uptake rates were approximately 5.5-fold greater at low pH (6.86) compared to the high pH (8.78), most likely due to the unionized, lipophilic form of TFM existing in greater amounts at a lower pH. In contrast, elimination rates following the injection of 85nmolTFMg^-1 body mass were 1.7-1.8 fold greater at pH8.96 than at pH6.43 during 2-4h of depuration in TFM-free water. Greater initial excretion rates at pH8.96 were presumably due to predicted increases in outward concentration gradients of un-ionized TFM. The present findings suggest that TFM is mainly taken-up in its un-ionized form, more lipophilic form, but there is also significant uptake of the ionized form of TFM via an unknown mechanism. Moreover, we provide an explanation to how small increases in pH can undermine lampricide treatment success increasing residual lamprey populations.

Celecoxib affects estrogen sulfonation catalyzed by several human hepatic sulfotransferases, but does not stimulate 17-sulfonation in rat liver

Celecoxib is known to alter the preferred position of SULT2A1-catalyzed sulfonation of 17β-estradiol (17β-E2) and other estrogens from the 3- to the 17-position. Understanding the effects of celecoxib on estrogen sulfonation is of interest in the context of the investigational use of celecoxib to treat breast cancer. This study examined the effects on celecoxib on cytosolic sulfotransferases in human and rat liver and on SULT enzymes known to be expressed in liver. Celecoxib's effects on the sulfonation of several steroids catalyzed by human liver cytosol were similar but not identical to those observed previously for SULT2A1. Celecoxib was shown to inhibit recombinant SULT1A1-catalyzed sulfonation of 10nM estrone and 4μM p-nitrophenol with IC₅₀ values of 2.6 and 2.1μM, respectively, but did not inhibit SULT1E1-catalyzed estrone sulfonation. In human liver cytosol, the combined effect of celecoxib and known SULT1A1 and 1E1 inhibitors, quercetin and triclosan, resulted in inhibition of 17β-E2-3-sulfonation such that the 17-sulfate became the major metabolite: this is of interest because the 17-sulfate is not readily hydrolyzed by steroid sulfatase to 17β-E2. Investigation of hepatic cytosolic steroid sulfonation in rat revealed that celecoxib did not stimulate 17β-E2 17-sulfonation in male or female rat liver as it does with human SULT2A1 and human liver cytosol, demonstrating that rat is not a useful model of this effect. In silico studies suggested that the presence of the bulky tryptophan residue in the substrate-binding site of the rat SULT2A homolog instead of glycine as in human SULT2A1 may explain this species difference.

Antiproliferation and antibacterial effect of biosynthesized AgNps from leaves extract of Guiera senegalensis and its catalytic reduction on some persistent organic pollutants

The study concentrate on the biosynthesis of silver nanoparticles (AgNps) from the leaves extract of Guiera senegalensis with focus on its; antiproliferation effect on prostate (PC3), breast (MCF7) and liver (HepG2) cancer cell lines, antibacterial effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and the degradation on 4-nitrophenol (4-NP) and congo red dye (CR). The synthesized AgNps were characterized by FTIR, TEM, FESEM, XRD and EDX analysis. The EDS spectrum revealed that the synthesized nanoparticles (Nps) were composed of 55.45% Ag atoms of spherical shape with approximately 50nm size, identified from TEM and FESEM data. The antiproliferation effect of the AgNps varies with cell lines in a concentration dependent manner. The result showed that the AgNps were more effective on PC3 (IC₅₀ 23.48μg/mL) than MCF7 (29.25μg/mL) and HepG2 (33.25μg/mL) by the virtue of their IC₅₀ values. The AgNps were highly effective against E. coli and S. aureus by killing 99% colonies. The AgNps also shows a good catalytic reduction of the toxic organic pollutants in which only 3mg of the AgNps degraded 95% of both CR dye and 4-NP in 22 and 36min respectively. Therefore, the green synthesis of AgNps may have potential applications in pharmacology and industries for the treatment of cancers, bacterial infections and in degrading toxic organic pollutants in water.

CF2H, a Hydrogen Bond Donor

The CF₂H group, a potential surrogate for the OH group, can act as an unusual hydrogen bond donor, as confirmed by crystallographic, spectroscopic, and computational methods. Here, we demonstrate the bioisosterism of the OH and CF₂H groups and the important roles of CF₂-H···O hydrogen bonds in influencing intermolecular interactions and conformational preferences. Experimental evidence, corroborated by theory, reveals the distinctive nature of CF₂H hydrogen bonding interactions relative to their normal OH hydrogen bonding counterparts.

Formation of iron oxide/Pd hybrid nanostructures with enhanced peroxidase-like activity and catalytic reduction of 4-nitrophenol

Iron oxide/Pd hybrid nanostructures with controllable Pd loading from 0.05 to 1.0 (calculated as Pd/Fe molar ratio) have been synthesized by chemical reduction of Pd²⁺ on iron oxide particles. The combination of iron oxide and Pd exhibits enhanced peroxidase-like activity and catalytic activity toward reduction of 4-nitrophenol. The catalytic enhancements were found to be dependent on the Pd loading amount as well as the synergistic effect between iron oxide and Pd. These results suggest that iron oxide with unique surface chemical state can be an active supporter and suggest an effective way to design superior hybrid nanostructures for catalytic applications.

Anticancer, antibacterial and pollutant degradation potential of silver nanoparticles from Hyphaene thebaica

We present here the biosynthesis of AgNps from the aqueous extract of H. thebaica fruit, and monitored through UV-Vis spectrophotometer. The functional group were characterized through ATR-FTIR spectroscopy, the particle size, morphologies and elemental composition of the nanoparticles were investigated by using TEM, FESEM and EDS respectively. The anti-proliferation activity of the synthesized AgNps was carried out using MTT assay on human prostate (PC3), breast (MCF7) and liver (HepG2) cancer cell lines. The anti-proliferation assay showed that the AgNps were able to inhibit the proliferation of the cancer cell lines in a dose depending manner. The effect was found more pronounced on prostate (IC₅₀ 2.6 mg/mL) followed by breast (IC₅₀ 4.8 mg/mL) and then liver cancer cell lines (IC₅₀ 6.8 mg/mL). The prepared AgNps were found to inhibit 99% growth of both E. coli and S. aureus after 24 h of incubation. The nanoparticles were used for the degradation of 4-nitrophenol (4-NP) and Congo red dyes (CR), which efficiently degrade CR, but make complex formation with 4-NP. Therefore, the AgNps synthesized from the aqueous fruit extract of H. thebaica have potential application in pharmacology and waste water treatment.

Catalytic reduction of 4-nitrophenol and photo inhibition of Pseudomonas aeruginosa using gold nanoparticles as photocatalyst

A simple, green method is described for the synthesis of Gold (Au) nanoparticles (NPs) using Cotoneaster horizontalis extract as a phyto-reducer and capping agent with superior photo inhibition activity against Pseudomonas aeruginosa. Different from the other methods used elevated temperatures for nanoparticles synthesis, the novelty of our method lies in its energy saving process and fast synthesis rates (~5min for AuNPs), and its potential to tune the nanoparticles size and afterward their catalytic activity. The starch, fatty acid and reducing sugars present in the extract are mostly responsible for repaid reduction rate Au⁺³ ions to AuNPs. Strong Plasmon resonance (SPR) of AuNPs was observed at 560nm, which indicates the formation of gold nanoparticles. Uv-visible spectroscopy, high resolution transmission electron microscope (HRTEM) and energy dispersion X-ray diffraction (XRD) were preformed to find out the formation of AuNPs. Proficient reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) in the presence of AuNPs and NaBH₄ was observed and was found to depend upon the nanoparticle size or the extract concentration. The AuNPs was also evaluated for antibacterial against P. aeruginosa. Before transferred it into antibacterial activity, it placed under visible light for 120min. The same experiment was performed in dark as control medium. The photo irradiated AuNPs was observed to be more effective against P. aeruginosa. The result showed that diameter of zone of inhibition of visible light irradiated AuNPs against P. aeruginosa was 17 (±0.5) and in dark was 8 (±0.4) mm.

Simultaneous AuIII Extraction and In Situ Formation of Polymeric Membrane-Supported Au Nanoparticles: A Sustainable Process with Application in Catalysis

A polymeric membrane-supported catalyst with immobilized gold nanoparticles (AuNPs) was prepared through the extraction and in situ reduction of Au^III salts in a one-step strategy. Polymeric inclusion membranes (PIMs) and polymeric nanoporous membranes (PNMs) were tested as different membrane-support systems. Transport experiments indicated that PIMs composed of cellulose triacetate, 2-nitrophenyloctyl ether, and an aliphatic tertiary amine (Adogen 364 or Alamine 336) were the most efficient supports for Au^III extraction. The simultaneous extraction and reduction processes were proven to be the result of a synergic phenomenon in which all the membrane components were involved. Scanning electron microscopy characterization of cross-sectional samples suggested a distribution of AuNPs throughout the membrane. Transmission electron microscopy characterization of the AuNPs indicated average particle sizes of 36.7 and 2.9 nm for the PIMs and PNMs, respectively. AuNPs supported on PIMs allowed for >95.4 % reduction of a 0.05 mmol L^-1 4-nitrophenol aqueous solution with 10 mmol L^-1 NaBH₄ solution within 25 min.

Anchoring of silver nanoparticles on graphitic carbon nitride sheets for the synergistic catalytic reduction of 4-nitrophenol

In this paper, a facile process was developed for anchoring of silver nanoparticles on graphitic carbon nitride sheets (Ag/g-C₃N₄) with high catalytic activity for reduction of 4-nitrophenol. The morphology and structure of the as-prepared Ag/g-C₃N₄ composite were investigated by FESEM, TEM, XRD and XPS. The reaction mechanism and the reduction kinetics of 4-nitrophenol under different light irradiation were systematically studied. The results showed that the obtained Ag/g-C₃N₄ composite exhibited a much higher electro/photo catalytic activity and stability for reduction of 4-nitrophenol. Significantly, due to the synergistic effect and interaction between highly dispersed Ag nanoparticles (Ag NPs, ∼7.2 nm) and lamellar g-C₃N₄, not only transfer of interfacial charge, but also the separation of photoinduced electrons occurred when the reaction was proceeded under light. In addition, the composite exhibited high stability and reusability during the cycling experiments. The results showed that the Ag/g-C₃N₄ composite is an effective and stable electro/photo catalyst for reduction of 4-nitrophenol.

Enhanced reactivity of microscale Fe/Cu bimetallic particles (mFe/Cu) with persulfate (PS) for p-nitrophenol (PNP) removal in aqueous solution

In this study, batch experiments were conducted to examine the enhanced reactivity of microscale Fe/Cu bimetallic particles (mFe/Cu) with persulfate (PS) for p-nitrophenol (PNP) removal in aqueous solution. The key operating parameters (i.e., theoretical Cu mass loadings (TML_Cu), mFe/Cu dosage, PS dose, initial pH and temperature) were optimized by the batch experiments, respectively. The experimental data were followed well the pseudo-first-order kinetic model. Result reveals that refractory PNP (500 mg L^-1) was effectively degraded by mFe/Cu-PS system with removal of 98.4% and k_obs of 1.91 min^-1 after only 3 min treatment under the optimal operating conditions. Moreover, compared with control experiments (i.e., mFe/Cu, microscale Fe⁰ with PS (mFe⁰-PS), and PS alone), mFe/Cu-PS system exerted better performance for PNP removal due to the strong synergistic effect between PS and mFe/Cu. According to the analysis results of degradation kinetics of PNP, COD (chemical oxygen demand) removal, UV-vis absorption spectra and the intermediates formed, the results reveal that the PNP removal by mFe/Cu-PS system was mainly attributed to reduction accompanied slight oxidation. And based on the analysis of surface characteristics of mFe/Cu particles, it is further demonstrated that PS could enhance the reactivity of mFe/Cu through rapid corrosion of iron surface and decrease of surface passivation of mFe/Cu surface when the low molar ratio of PS to mFe/Cu (i.e., 1:43) was used in this study. These results also illustrates mFe/Cu-PS can be as a high efficient pretreatment technology for the removal of toxic refractory PNP from wastewater.

Selection of active phase of MnO2 for catalytic ozonation of 4-nitrophenol

Catalytic ozonation is a highly effective method in wastewater treatment, and MnO₂ materials are widely recognized as active heterogeneous catalysts in this process. Many works reported the progress in active MnO₂ synthesis, but the active phase is rarely systematically studied. In this paper, all six phases of MnO₂ (α-, β-, δ-, γ-, λ- and ε-) were synthesized by facile methods. Their catalytic activities in ozonation of 4-nitrophenol (4-NP) were evaluated and correlated with the physicochemical properties obtained from X-ray Diffraction (XRD), transmission electron microscopy (TEM), physical adsorption and cyclic voltammetry (CV) analysis. α- MnO₂ was found to be the most active catalyst in 4-NP degradation at neutral pH. MnO₂ with low average oxidation state (AOS) showed stronger oxidation/reduction peaks in CV characterization, which benefited catalytic decomposition of ozone to generate active species. Superoxide radical was confirmed as the main oxidizing species, along with singlet oxygen and ozone molecule oxidation in bulk solution and little contribution of oxidation on the MnO₂ surface. Mn²⁺ leaching happened during catalytic ozonation, but its catalytic role is negligible. This result may give rise to the preparation of new active MnO₂ catalysts.

Green synthesis of Pd/walnut shell nanocomposite using Equisetum arvense L. leaf extract and its application for the reduction of 4-nitrophenol and organic dyes in a very short time

Palladium nanoparticles (PdNPs) have been immobilized on the surface of walnut shell powder using Equisetum arvense L. leaf extract as reducing and stabilizing agents in this work. FT-IR spectroscopy, UV-Vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction (XRD) pattern, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM) have been used in the characterization of the nanocomposites thus prepared. High catalytic activity was shown by these nanocomposites in the reduction of different dyes. The PdNPs' diameter on the walnut shell was predominantly found within the 5-12-nm range. The advantages of these catalysts include facile and clean synthesis, simple preparation procedure, excellent properties, alterable supports, and low cost, which make them applicable in reduction of 4-nitrophenol (4-NP), Congo red (CR), methylene blue (MB), and rhodamine B (RhB) in the presence of aqueous NaBH₄ at room temperature. Pd/walnut shell nanocomposites were highly active catalysts for reduction of these dyes. Moreover, Pd/walnut shell nanocomposite can be recovered and recycled seven times without any appreciable loss of catalytic activity. Graphical abstract Waste walnut shell as a natural valuable resource support for green synthesis of Pd/walnut shell nanocomposite using Equisetum arvense L. leaf extract and its application for the reduction of 4-nitrophenol and organic dyes in a very short time.

Crystal Structure and Functional Characterization of an Esterase (EaEST) from Exiguobacterium antarcticum

A novel microbial esterase, EaEST, from a psychrophilic bacterium Exiguobacterium antarcticum B7, was identified and characterized. To our knowledge, this is the first report describing structural analysis and biochemical characterization of an esterase isolated from the genus Exiguobacterium. Crystal structure of EaEST, determined at a resolution of 1.9 Å, showed that the enzyme has a canonical α/β hydrolase fold with an α-helical cap domain and a catalytic triad consisting of Ser96, Asp220, and His248. Interestingly, the active site of the structure of EaEST is occupied by a peracetate molecule, which is the product of perhydrolysis of acetate. This result suggests that EaEST may have perhydrolase activity. The activity assay showed that EaEST has significant perhydrolase and esterase activity with respect to short-chain p-nitrophenyl esters (≤C8), naphthyl derivatives, phenyl acetate, and glyceryl tributyrate. However, the S96A single mutant had low esterase and perhydrolase activity. Moreover, the L27A mutant showed low levels of protein expression and solubility as well as preference for different substrates. On conducting an enantioselectivity analysis using R- and S-methyl-3-hydroxy-2-methylpropionate, a preference for R-enantiomers was observed. Surprisingly, immobilized EaEST was found to not only retain 200% of its initial activity after incubation for 1 h at 80°C, but also retained more than 60% of its initial activity after 20 cycles of reutilization. This research will serve as basis for future engineering of this esterase for biotechnological and industrial applications.

Biodegradation and detoxification of chloronitroaromatic pollutant by Cupriavidus

Current study reports isolation of Cupriavidus strain a3 which can utilize 2-chloro-4-nitrophenol (C4NP) as sole source of carbon and nitrogen, leading to its detoxification. Degradation process was initiated by release of nitrite ion resulting in the formation of 2-chlorohydroquinone as intermediate. The nitrite releasing activity was also evident in the cell free protein extract. Different parameters for 2C4NP biodegradation were optimized. The degradation pattern followed Haldane substrate inhibition model with maximum specific degradation rate (q_max) of 0.13/h, half saturation constant (K_s) of 0.05mM, and 2C4NP inhibition constant (K_i) of 0.64mM. The isolate was successfully applied to remediation of 2C4NP-contaminated soil in microcosm study. 2-Dimensional protein electrophoresis analysis showed that growth of the isolate in the presence of 2C4NP resulted in modification of membrane permeability and induction of signal transduction protein. In our knowledge, this is the first study reporting degradation and detoxification of 2C4NP by Cupriavidus.

Bioreductive deposition of highly dispersed Ag nanoparticles on carbon nanotubes with enhanced catalytic degradation for 4-nitrophenol assisted by Shewanella oneidensis MR-1

Biogenetic nanomaterials research provides insights and valuable implications for the green synthesis of nanomaterials and auxiliary biodegradation behaviors. Ag nanoparticles (Ag NPs) fabricated on multiwalled carbon nanotubes (MWNTs) (Ag/MWNTs nanocomposites) are prepared in situ assisted by Shewanella oneidensis MR-1 (S. oneidensis MR-1) that provide respiratory pathway to transmit electrons. The Ag/MWNTs nanocomposites are characterized by a scanning electron microscopy (SEM), an energy dispersive X-ray (EDX), a transmission electron microscopy (TEM), an X-ray diffraction (XRD), and an X-ray photoelectron spectroscopy (XPS), respectively. The results indicate that Ag NPs (less than 20 nm in diameter) are successfully formed on the MWNTs without an aggregation. In application studies, the catalytic activities of the Ag/MWNTs nanocomposites towards the reduction of 4-nitrophenol (4-NP) by sodium borohydride (NaBH₄) are tracked by a UV-visible spectroscopy. It is suggested that the Ag/MWNTs nanocomposites exhibit a satisfactory catalytic efficiency, which might be ascribed to the high dispersion of Ag NPs on MWNT surfaces. Moreover, the final results indicate that only after 10 min of reaction, the catalytic degradation ratio of 4-NP reaches 94.0% in the presence of Ag/MWNTs nanocomposites assisted by S. oneidensis MR-1.

Efficient 2-Nitrophenol Chemical Sensor Development Based on Ce2O3 Nanoparticles Decorated CNT Nanocomposites for Environmental Safety

Ce₂O₃ nanoparticle decorated CNT nanocomposites (Ce₂O₃.CNT NCs) were prepared by a wet-chemical method in basic medium. The Ce₂O₃.CNT NCs were examined using FTIR, UV/Vis, Field-Emission Scanning Electron Microscopy (FESEM), X-ray electron dispersive spectroscopy (XEDS), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). A selective 2-nitrophenol (2-NP) sensor was developed by fabricating a thin-layer of NCs onto a flat glassy carbon electrode (GCE, surface area = 0.0316 cm²). Higher sensitivity including linear dynamic range (LDR), long-term stability, and enhanced electrochemical performances towards 2-NP were achieved by a reliable current-voltage (I-V) method. The calibration curve was found linear (R² = 0.9030) over a wide range of 2-NP concentration (100 pM ~ 100.0 mM). Limit of detection (LOD) and sensor sensitivity were calculated based on noise to signal ratio (~3N/S) as 60 ± 0.02 pM and 1.6×10⁻³ μAμM^-1cm^-2 respectively. The Ce₂O₃.CNT NCs synthesized by a wet-chemical process is an excellent way of establishing nanomaterial decorated carbon materials for chemical sensor development in favor of detecting hazardous compounds in health-care and environmental fields at broad-scales. Finally, the efficiency of the proposed chemical sensors can be applied and utilized in effectively for the selective detection of toxic 2-NP component in environmental real samples with acceptable and reasonable results.

Nickel nanoparticles-chitosan composite coated cellulose filter paper: An efficient and easily recoverable dip-catalyst for pollutants degradation

In this report, we used cellulose filter paper (FP) as high surface area catalyst supporting green substrate for the synthesis of nickel (Ni) nanoparticles in thin chitosan (CS) coating layer and their easy separation was demonstrated for next use. In this work, FP was coated with a 1 wt% CS solution onto cellulose FP to prepare CS-FP as an economical and environment friendly host material. CS-FP was put into 0.2 M NiCl₂ aqueous solution for the adsorption of Ni²⁺ ions by CS coating layer. The Ni²⁺ adsorbed CS-FP was treated with 0.1 M NaBH₄ aqueous solution to convert the ions into nanoparticles. Thus, we achieved Ni nanoparticles-CS composite through water based in-situ preparation process. Successful Ni nanoparticles formations was assessed by FESEM and EDX analyses. FTIR used to track the interactions between nanoparticles and host material. Furthermore, we demonstrated that the nanocomposite displays an excellent catalytic activity and reusability in three reduction reactions of toxic compounds i.e. conversion of 4-nitrophenol to 4-aminophenol, 2-nitrophenol to 2-aminophenol, and methyl orange dye reduction by NaBH₄. Such a fabrication process of Ni/CS-FP may be applicable for the immobilization of other metal nanoparticles onto FP for various applications in catalysis, sensing, and environmental sciences.

Application of pseudo-emulsion-based hollow fiber strip dispersion for the extraction of p-nitrophenol from aqueous solutions

The extraction of p-nitrophenol (PNP) from aqueous solutions through a pseudo-emulsion hollow fiber strip dispersion (PEHFSD) system was conducted in a microporous hydrophobic polypropylene hollow fiber membrane contactor. For the optimization of the process variables, face-centered central composite design (FCCD) has been used. It was observed that initial feed concentration, carrier composition and stripping phase concentration were the three FCCD factors, which influenced the nitrophenol extraction. Using the optimized process conditions for the separation of PNP, experiments were also performed for the separation of other nitrophenols through PEHFSD system. By the FCCD design and analysis, almost 99% extraction of all three nitrophenols was achieved at optimum conditions. A mass transfer model was also developed and aqueous and membrane resistances were evaluated as 196.46 s cm(-1) and 50.14 s cm(-1), respectively.

Microbial community and metabolism activity in a bioelectrochemical denitrification system under long-term presence of p-nitrophenol

Bioelectrochemical denitrification system (BEDS) is a promising technology for nitrate removal from wastewaters. The hazards and effects concerning p-nitrophenol (PNP) towards BEDS lack enough investigations and possess great research prospects. This study investigated how PNP affected the nitrate removal efficiency, microbial communities, functional denitrifying genes abundances, nitrate and nitrite reductase activities, diffusible signal factors (DSF) release, and extracellular polymeric substances (EPS) production in the BEDS. Results indicated that nitrate removal efficiency decreased with initial PNP concentration increased from 0 to 100mg/L. Phylum Firmicutes and class Clostridia were the main contributors for denitrification process in this BEDS. The abundances of the denitrifying genes nirS, nirK, napA, and narG all presented decreased trends with increasing PNP. In addition, the concentrations of nitrate reductase (NR), nitrite reductase (NIR), and EPS obviously decreased, while the concentration of DSF increased with increasing PNP, which demonstrated that higher PNP would inhibit the biofilm formation.