Nitrobenzene compounds are highly toxic pollutants with good stability, and they have a major negative impact on both human health and the ecological environment. Herein, it was found for the first ...time that fluorescent DNA-silver nanoclusters (DNA-AgNCs) can catalyze the reduction of toxic and harmful nitro compounds into less toxic amino compounds with excellent tolerance to high temperature and organic solvents. In this study, the reduction of p-nitrophenol (4-NP) as a model was systematically investigated, followed by expending the substrate to disclose the versatility of this reaction. This report not only expanded the conditions for utilizing catalytic reduction conditions of DNA-AgNCs as an efficient catalyst in the control of hazardous chemicals but also widened the substrate range of DNA-AgNCs reduction, providing a new angle for the application of noble metal nanoclusters.
•A silsesquioxane polymer was used as a stabilizer for synthesis of gold nanoparticles.•Gold nanoparticles were obtained with an average particle size of 4.5nm.•A sensor was built for individual and ...simultaneous detection of nitrophenol isomers.
The water-soluble 3-n-propyl-4-picolinium silsesquioxane chloride (Si4Pic+Cl−) polymer was prepared, characterized and used as a stabilizing agent for the synthesis of gold nanoparticles (nAu). The ability of Si4Pic+Cl− to adsorb anionic metal complexes such as AuCl4− ions allowed well-dispersed nAu to be obtained with an average particle size of 4.5nm. The liquid suspension of nAu-Si4Pic+Cl− was deposited by the drop coating method onto a glassy carbon electrode (GCE) surface to build a sensor (nAu-Si4Pic+Cl−/GCE) which was used for the detection of o-nitrophenol (o-NP) and p-nitrophenol (p-NP). Under optimized experimental conditions the reduction peak current increased with increasing concentrations of both nitrophenol isomers in the range of 0.1–1.5μmolL−1. The detection limits were 46nmolL−1 and 55nmolL−1 for o-NP and p-NP, respectively. These findings indicate that the nAu-Si4Pic+Cl− material is a very promising candidate to assemble electrochemical sensors for practical applications in the field of analytical chemistry.
Cellular senescence is a stress response that imposes stable cell-cycle arrest in damaged cells, preventing their propagation in tissues. However, senescent cells accumulate in tissues in advanced ...age, where they might promote tissue degeneration and malignant transformation. The extent of immune-system involvement in regulating age-related accumulation of senescent cells, and its consequences, are unknown. Here we show that Prf1
mice with impaired cell cytotoxicity exhibit both higher senescent-cell tissue burden and chronic inflammation. They suffer from multiple age-related disorders and lower survival. Strikingly, pharmacological elimination of senescent-cells by ABT-737 partially alleviates accelerated aging phenotype in these mice. In LMNA
progeroid mice, impaired cell cytotoxicity further promotes senescent-cell accumulation and shortens lifespan. ABT-737 administration during the second half of life of these progeroid mice abrogates senescence signature and increases median survival. Our findings shed new light on mechanisms governing senescent-cell presence in aging, and could motivate new strategies for regenerative medicine.
Triple-negative breast cancer (TNBC) accounts for nearly one-quarter of all breast cancer cases, but effective targeted therapies for this disease remain elusive because TNBC cells lack expression of ...the three most common receptors seen on other subtypes of breast cancer. Here, we exploit TNBC cells’ overexpression of Notch-1 receptors and Bcl-2 anti-apoptotic proteins to provide an effective targeted therapy. Prior studies have shown that the small molecule drug ABT-737, which inhibits Bcl-2 to reinstate apoptotic signaling, is a promising candidate for TNBC therapy. However, ABT-737 is poorly soluble in aqueous conditions, and its orally bioavailable derivative causes severe thrombocytopenia. To enable targeted delivery of ABT-737 to TNBC and enhance its therapeutic efficacy, we encapsulated the drug in poly(lactic-co-glycolic acid) nanoparticles (NPs) that were functionalized with Notch-1 antibodies to produce N1-ABT-NPs. The antibodies in this NP platform enable both TNBC cell-specific binding and suppression of Notch signaling within TNBC cells by locking the Notch-1 receptors in a ligand unresponsive state. This Notch inhibition potentiates the effect of ABT-737 by up-regulating Noxa, resulting in effective killing of TNBC cells. We present the results of in vitro studies that demonstrate N1-ABT-NPs can preferentially bind TNBC cells versus noncancerous breast epithelial cells to effectively regulate Bcl-2 and Notch signaling to induce cell death. Further, we show that N1-ABT-NPs can accumulate in subcutaneous TNBC xenograft tumors in mice following systemic administration to reduce tumor burden and extend animal survival. Together, these findings demonstrate that NP-mediated co-delivery of Notch-1 antibodies and ABT-737 is a potent treatment strategy for TNBC that may improve patient outcomes with further development and implementation.
A systematic literature review of in vitro studies was performed to identify methane (CH4) mitigation interventions with a potential to reduce CH4 emission in vivo. Data from 277 peer-reviewed ...studies published between 1979 and 2018 were reviewed. Individual CH4 mitigation interventions were classified into 14 categories of feed additives based on their type, chemical composition, and mode of action. Response variables evaluated were absolute CH4 emission (number of treatment means comparisons = 1,325); total volatile fatty acids (n = 1,007), acetate (n = 783), propionate (n = 792), and butyrate (n = 776) concentrations; acetate to propionate ratio (n = 675); digestibility of dry matter (n = 489), organic matter (n = 277), and neutral detergent fiber (n = 177). Total gas production was used as an explanatory variable in the model for CH4 production. Relative mean difference between treatment and control means reported in the studies was calculated and used for statistical analysis. The robust variance estimation method was used to analyze the effects of CH4 mitigation interventions. In vitro CH4 production was decreased by antibodies (−38.9%), chemical inhibitors (−29.2%), electron sinks (−18.9%), essential oils (−18.2%), plant extracts (−14.5%), plant inclusion (−11.7%), saponins (−14.8%), and tannins (−14.5%). Overall effects of direct-fed microbials, enzymes, macroalgae, and organic acids supplementation did not affect CH4 production in the current meta-analysis. When considering the effects of individual mitigation interventions containing a minimum number of 4 degrees of freedom within feed additives categories, Enterococcus spp. (i.e., direct-fed microbial), nitrophenol (i.e., electron sink), and Leucaena spp. (i.e., tannins) decreased CH4 production by 20.3%, 27.1%, and 23.5%, respectively, without extensively, or only slightly, affecting ruminal fermentation and digestibility of nutrients. It should be noted, however, that although the total number of publications (n = 277) and treatment means comparisons (n = 1,325 for CH4 production) in the current analysis were high, data for most mitigation interventions were obtained from less than 5 observations (e.g., maximum number of observations was 4, 7, and 22 for nitrophenol, Enterococcus spp., and Leucaena spp., respectively), because of limited data available in the literature. These should be further evaluated in vitro and in vivo to determine their true potential to decrease enteric CH4 production, yield, and intensity. Some mitigation interventions (e.g., magnesium, Heracleum spp., nitroglycerin, β-cyclodextrin, Leptospermum pattersoni, Fructulus Ligustri, Salix caprea, and Sesbania grandiflora) decreased in vitro CH4 production by over 50% but did not have enough observations in the database. These should be more extensively investigated in vitro, and the dose effect must be considered before adoption of mitigation interventions in vivo.
•P450 116B5 heme domain was expressed in E. coli. and purified in a stable form.•Differential scanning calorimetry showed that the enzyme is stable up to 50 °C at pH 6.8.•High reduction potential and ...stability to H2O2 for peroxygenase activity.•Activity on aromatic compounds, diclofenac and tamoxifen demonstrated.
The heme domain of cytochrome P450 116B5 from Acinetobacter radioresistens (P450 116B5hd), a self-sufficient class VII P450, was functionally expressed in Escherichia coli, purified and characterised in active form. Its unusually high reduction potential (-144 ± 42 mV) and stability in the presence of hydrogen peroxide make this enzyme a good candidate for driving catalysis with the so-called peroxide shunt, avoiding the need for a reductase and the expensive cofactor NAD(P)H. The enzyme is able to carry out the peroxide-driven hydroxylation of aromatic compounds such as p-nitrophenol (KM = 128.85 ± 29.51 μM and kcat = 2.65 ± 0.14 min−1), 10-acetyl-3,7-dihydroxyphenoxazine (KM = 6.01 ± 0.32 μM and kcat = 0.33 ± 0.03 min−1), and 3,5,3′,5′tetramethylbenzidine (TMB). Moreover, it catalyses different reactions on well-known drugs such as hydroxylation of diclofenac (KM = 49.60 ± 6.30 μM and kcat = 0.06 ± 0.01 min−1) and N-desmethylation of tamoxifen (KM = 57.20 ± 7.90 μM and kcat = 0.79 ± 0.04 min−1). The data demonstrate that P450 116B5hd is an efficient biocatalyst for sustainable applications in bioremediation and human drug metabolite production.
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•Green synthesis of Pd/RGO/Fe3O4 nanocomposite using Withania coagulans leaf extract.•Reduction of 4-nitrophenol in water at room temperature.•Characterization of catalyst by XRD, ...FE-SEM, EDS, VSM, TEM, FT-IR and UV–vis.•The catalyst can be recovered and reused for further catalytic reactions with almost no loss in activity.
A reduced graphene oxide (RGO)/Fe3O4 based nanocomposite with palladium nanoparticles (Pd NPs) has been synthesized via a green route by Withania coagulans leaf extract as a reducing and stabilizing agent and its catalytic activity has been tested for the reduction of 4-nitrophenol (4-NP) in water at room temperature. The hydroxyl groups of phenolics in W. coagulans leaf extract is directly responsible for the reduction of Pd2+, Fe3+ ions and GO. The nanocomposite was characterized by X-ray diffraction (XRD), fourier transformed infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), Vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM). Furthermore, due to the magnetic separability and high stability of the composite the catalyst can be recovered and recycled several times without marked loss of activity.
Herein, we present the exceptional performance of FeC
-coated carbon sheets (FC) derived from the pyrolysis of waste biomass as a bifunctional catalyst for electrochemical detection and catalytic ...reduction of 4-nitrophenol (4-NP). Despite having a lower surface area, larger particle size, and lesser N content, the FC material prepared at a calcination temperature of 900 °C (FC
) outperforms the other samples. Deeper investigations revealed that the FC
efficiently facilitates the charge transfer process and enhances the diffusion rate of 4-NP, leading to increased surface coverage of 4-NP on the surface of FC
. Additionally, relatively weaker interactions between 4-NP and FC
allow the facile adsorption and desorption of reaction intermediates. Due to the synergetic interplay of these factors, FC
exhibited a linear response to changes in 4-NP concentration from 1 μM to 100 μM with a low limit of detection (LOD) of 84 nM (S/N = 3) and high sensitivity of 12.15 μA μM
cm
. Importantly, it selectively detects 4-NP in the presence of five times more concentrated 2-aminophenol, 4-aminophenol, catechol, resorcinol, and hydroquinone and ten times more concentrated metal salts such as Na
SO
. NaNO
, KCl, CuCl
, and CaCl
. Moreover, FC
can accurately detect micromolar levels of 4-NP in river water with high recovery values (99.8-103.5 %). In addition, FC
exhibited outstanding catalytic activity in reducing 4-NP to 4-aminophenol (4-AP), achieving complete conversion within 8 min with a high-rate constant of 0.42 min
. FC
also shows high recyclability in six consecutive catalytic reactions due to Fe magnetic property.
The effect of nitrophenolic shock loads on the performance of three lab scale SBRs was studied using a synthetic feed. Nitrophenols were biotransformed by Simultaneous heterotrophic Nitrification and ...aerobic Denitrification (SND) using a specially designed single sludge biomass containing Thiosphaera pantotropha. Reactors R1, R2 and R3 were fed with 200mg/L concentration of 4-nitrophenol (4-NP), 2,4-dinitrophenol (2,4-DNP), and 2,4,6-trinitrophenol (2,4,6-TNP) whereas reactor R was used as a background control. Three nitrophenolic shock loadings of 400, 600 and 800mg/Ld were administrated by increasing the influent nitrophenolic concentration while keeping the hydraulic retention time as 48h. The shocks were given continuously for a period of 4 days before switching back to normal nitrophenolic loading (200mg/Ld). The reactors were allowed to recover to normal performance level before administrating the next nitrophenolic shock load. The study showed that a nitrophenolic shock load, as high as 600mg/Ld was completely degraded by the 4-NP & 2,4-DNP bioreactors while almost half degraded by the 2,4,6-TNP bioreactor without affecting the reactor’s performance irreversibly. After resuming the normal nitrophenolic loading, it took almost 8–10 days for the reactors to recover from the shock effect. The study was further extended to evaluate the maximum possible mixed nitrophenolic loading (4-NP:2,4-DNP:2,4,6-TNP 1:1:1) to which a reactor (R3) containing 2,4,6-TNP acclimated single sludge biomass can be exposed without hampering the reactor performance irreversibly. The reactor was able to achieve pseudo-steady-state at a mixed nitrophenolic loading of 300mg/Ld with more than 90% removal of all the three nitrophenols, but could remove half of the mixed nitrophenolic loading of 600mg/Ld.
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► Nitrophenols were used as the sole source of carbon, nitrogen and energy. ► A SND based SBR containing a single sludge with Thiosphaera pantotropha was used. ► SBR could completely degrade a shock load of 600mg/Ld of 4-NP & 2,4-DNP while half degrade 2,4,6-TNP. ► The shock and mixed loading did not affect the reactors performance irreversibly. ► 2,4,6-trinitrophenol degrading SBR could half degrade a mixed load of 600mg/Ld.
P-nitrophenol is one of the most common contaminants in chemical industrial wastewater, and in situ real-time monitoring of PNP cannot be achieved by conventional analytical techniques. Here, a ...two-chamber microbial fuel cell with an aerobic anode chamber was tested as a biosensor for in situ real-time monitoring of PNP. Pseudomonas monteilii LZU-3, which was used as the biological recognition element, can form a biofilm on the anode electrode using PNP as a sole substrate. The optimal operation parameters of the biosensor were as follows: external resistance 1000Ω, pH 7.8, temperature 30°C, and maximum PNP concentration 50mgL−1. Under these conditions, the maximum voltages showed a linear relationship with PNP concentrations ranging from 15±5 to 44±4.5mgL−1. Furthermore, we developed a novel portable device for in situ real-time monitoring of PNP. When the device was applied to measure PNP in wastewater containing various additional aromatic compounds and metal ions, the performance of the biosensor was not affected and the correlation between the maximum voltages and the PNP concentrations ranging from 9±4mgL−1 to 36 ± 5mgL−1 was conserved. The results demonstrated that the MFC biosensor provides a rapid and cost-efficient analytical method for real-time monitoring of toxic and recalcitrant pollutants in environmental samples.
•Pseudomonas monteilii LZU-3 can degrade PNP and generate voltage in an aerobic anode MFC.•P. monteilii LZU-3 can form a biofilm on the anode electrode.•The maximum voltages showed a linear relationship with PNP concentrations.•A portable biosensor system was developed for real-time monitoring of PNP.
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