4-Nitrophenol at environmentally relevant concentrations mediates reproductive toxicity in Caenorhabditis elegans via metabolic disorders-induced estrogen signaling pathway.

4-Nitrophenol (4-NP), as a toxic and refractory pollutant, has generated significant concern due to its adverse effects. However, the potential toxic effects and mechanism remained unclear. In this study, the reproduction, development, locomotion and reactive oxygen species (ROS) production of Caenorhabditis elegans were investigated to evaluate the 4-NP toxicity. We used metabolomics to assess the potential damage mechanisms. The role of metabolites in mediating the relationship between 4-NP and phenotypes was examined by correlation and mediation analysis. 4-NP (8 ng/L and 8 µg/L) caused significant reduction of brood size, ovulation rate, total germ cells numbers, head thrashes and body bends, and an increase in ROS. However, the oosperm numbers in uterus, body length and body width were decreased in 8 µg/L. Moreover, 36 differential metabolites were enriched in the significant metabolic pathways, including lysine biosynthesis, ß-alanine metabolism, tryptophan metabolism, pentose phosphate pathway, pentose and glucuronate interconversions, amino sugar and nucleotide sugar metabolism, starch and sucrose metabolism, galactose metabolism, propanoate metabolism, glycerolipid metabolism, and estrogen signaling pathway. The mechanism of 4-NP toxicity was that oxidative stress caused by the perturbation of amino acid, which had effects on energy metabolism through disturbing carbohydrate and lipid metabolism, and finally affected the estrogen signaling pathway to exert toxic effects. Moreover, correlation and mediation analysis showed glycerol-3P, glucosamine-6P, glucosamine-1P, UDP-galactose, L-aspartic acid, and uracil were potential markers for the reproduction and glucose-1,6P2 for developmental toxicity. The results provided insight into the pathways involved in the toxic effects caused by 4-NP and developed potential biomarkers to evaluate 4-NP toxicity.

A dual-signal triple-readout optical sensing platform for α-glucosidase and ß-glucosidase activity monitoring and inhibitor screening based on luminescent covalent organic framework.

BACKGROUND: As promising biomarkers of diabetes, α-glucosidase (α-Glu) and ß-glucosidase (ß-Glu) play a crucial role in the diagnosis and management of diseases. However, there is a scarcity of techniques available for simultaneously and sensitively detecting both enzymes. What's more, most of the approaches for detecting α-Glu and ß-Glu rely on a single-mode readout, which can be affected by multiple factors leading to inaccurate results. Hence, the simultaneous detection of the activity levels of both enzymes in a single sample utilizing multiple-readout sensing approaches is highly attractive. RESULTS: In this work, we constructed a facile sensing platform for the simultaneous determination of α-Glu and ß-Glu by utilizing a luminescent covalent organic framework (COF) as a fluorescent indicator. The enzymatic hydrolysis product common to both enzymes, p-nitrophenol (PNP), was found to affect the fluorometric signal through an inner filter effect on COF, enhance the colorimetric response by intensifying the absorption peak at 400 nm, and induce changes in RGB values when analyzed using a smartphone-based color recognition application. By combining fluorometric/colorimetric measurements with smartphone-assisted RGB mode, we achieved sensitive and accurate quantification of α-Glu and ß-Glu. The limits of detection for α-Glu were determined to be 0.8, 1.22, and 1.85 U/L, respectively. Similarly, the limits of detection for ß-Glu were 0.16, 0.42, and 0.53 U/L, respectively. SIGNIFICANCE: Application of the proposed sensing platform to clinical serum samples revealed significant differences in the two enzymes between healthy people and diabetic patients. Additionally, the proposed sensing method was successfully applied for the screening of α-Glu inhibitors and ß-Glu inhibitors, demonstrating its viability and prospective applications in the clinical management of diabetes as well as the discovery of antidiabetic medications.

Carboxymethyl ß-Cyclodextrin Assistance for the 4-Nitrophenol Reduction Using Cobalt-Based Layered Double Hydroxides.

Cobalt-aluminum-layered double hydroxides containing carboxymethyl ß-cyclodextrin (CMßCD) were synthesized by coprecipitation and evaluated as a cobalt source for the 4-nitrophenol reduction in an aqueous medium. Several physicochemical techniques (XRD, FTIR, TGA) indicated the intercalation of the anionic cyclodextrin without damages to the hydrotalcite-type structure. These lamellar cobalt-aluminum hybrid materials (CoAl_CMßCD) were evaluated in the 4-nitrophenol reduction and showed higher activities in comparison with the CMßCD-free standard material (CoAl_CO3). To rationalize these results, a set of experimental controls going from physical mixtures of CoAl_CO3 with different cyclodextrins to other cobalt-based materials were investigated, highlighting the beneficial effects of both the layered double hydroxide and CMßCD-based hybrid structures. CMßCD also showed a beneficial effect as an additive during the 4-nitrophenol reduction. CoAl_CO3, dispersed in a fresh CMßCD solution could be re-used for five successive cycles without the loss of activity.

Biochemical characterization of an esterase from Thermobifida fusca YX with acetyl xylan esterase activity.

BACKGROUND: Esterases (EC 3.1.1.X) are enzymes that catalyze the hydrolysis ester bonds. These enzymes have large potential for diverse applications in fine industries, particularly in pharmaceuticals, cosmetics, and bioethanol production. METHODS AND RESULTS: In this study, a gene encoding an esterase from Thermobifida fusca YX (TfEst) was successfully cloned, and its product was overexpressed in Escherichia coli and purified using affinity chromatography. The TfEst kinetic assay revealed catalytic efficiencies of 0.58 s-1 mM-1, 1.09 s-1 mM-1, and 0.062 s-1 mM-1 against p-Nitrophenyl acetate, p-Nitrophenyl butyrate, and 1-naphthyl acetate substrates, respectively. Furthermore, TfEst also exhibited activity in a pH range from 6.0 to 10.0, with maximum activity at pH 8.0. The enzyme demonstrated a half-life of 20 min at 70 °C. Notably, TfEst displayed acetyl xylan esterase activity as evidenced by the acetylated xylan assay. The structural prediction of TfEst using AlphaFold indicated that has an α/ß-hydrolase fold, which is consistent with other esterases. CONCLUSIONS: The enzyme stability over a broad pH range and its activity at elevated temperatures make it an appealing candidate for industrial processes. Overall, TfEst emerges as a promising enzymatic tool with significant implications for the advancement of biotechnology and biofuels industries.

Toxicity of bisphenol A and p-nitrophenol on tomato plants: Morpho-physiological, ionomic profile, and antioxidants/defense-related gene expression studies.

Bisphenol A (BPA) and p-nitrophenol (PNP) are emerging contaminants of soils due to their wide presence in agricultural and industrial products. Thus, the present study aimed to integrate morpho-physiological, ionic homeostasis, and defense- and antioxidant-related genes in the response of tomato plants to BPA or PNP stress, an area of research that has been scarcely studied. In this work, increasing the levels of BPA and PNP in the soil intensified their drastic effects on the biomass and photosynthetic pigments of tomato plants. Moreover, BPA and PNP induced osmotic stress on tomato plants by reducing soluble sugars and soluble proteins relative to control. The soil contamination with BPA and PNP treatments caused a decline in the levels of macro- and micro-elements in the foliar tissues of tomatoes while simultaneously increasing the contents of non-essential micronutrients. The Fourier transform infrared analysis of the active components in tomato leaves revealed that BPA influenced the presence of certain functional groups, resulting in the absence of some functional groups, while on PNP treatment, there was a shift observed in certain functional groups compared to the control. At the molecular level, BPA and PNP induced an increase in the gene expression of polyphenol oxidase and peroxidase, with the exception of POD gene expression under BPA stress. The expression of the thaumatin-like protein gene increased at the highest level of PNP and a moderate level of BPA without any significant effect of both pollutants on the expression of the tubulin (TUB) gene. The comprehensive analysis of biochemical responses in tomato plants subjected to BPA and PNP stress illustrates valuable insights into the mechanisms underlying tolerance to these pollutants.

New insight on porcine carboxylesterases expression and activity in lung tissues.

Over the course of the last twenty years, there has been a growing recognition of the pig's potential as a valuable model for studying human drug metabolism. This study aimed to investigate the expression, enzymatic activity, inhibitory susceptibility, and cellular localization of carboxylesterases (CES) in porcine lung tissue not yet explored. Our results showed that CESs hydrolysis activity followed Michaelis-Menten kinetics in both cytosolic and microsomal fractions of porcine lung tissues (N = 8), with comparable hydrolysis rates for tested substrates, namely 4-nitrophenyl acetate (pNPA), 4-methylumbelliferyl acetate (4-MUA), and fluorescein diacetate (FD). We also determined the CESs hydrolysis activity in a representative sample of the porcine liver that, as expected, displayed higher activity than the lung ones. The study demonstrated variable levels of enzyme activities and interindividual variability in both porcine lung fractions. Inhibition studies used to assess the CESs' involvement in the hydrolysis of pNPA, 4-MUA, and FD suggested that CESs may be the enzymes primarily involved in the metabolism of ester compounds in the pig lung tissue. Overall, this study provides insight into the distribution and diversity of CES isoforms involved in substrate hydrolysis across different cellular fractions (cytosol and microsomes) in porcine lungs.

Enhancing the microbial advanced oxidation of P-nitrophenol in sediment through accelerating extracellular respiration with electrical stimulation.

Microbial advanced oxidation, a fundamental process for pollutant degradation in nature, is limited in efficiency by the weak respiration of indigenous microorganisms. In this study, an electric field was employed to enhance microbial respiration and facilitate the microbial advanced oxidation of p-nitrophenol (PNP) in simulated wetlands with alternation of anaerobic and aerobic conditions. With intermittent air aeration, an electric field of 0.8 V promoted extracellular electron transfer to increase Fe2+ generation through dissimilatory iron reduction and the production of hydroxyl radicals (•OH) through Fenton-like reactions. As a result, the PNP removal rate of the electrically-stimulated group was higher than that of the control (72.15 % vs 46.88 %). Multiple lines of evidence demonstrated that the electrically-induced polarization of respiratory enzymes expedited proton-coupled electron transfer within the respiratory chain to accelerate microbial advanced oxidation of PNP. The polarization of respiratory enzymes with the electric field hastened proton outflow to increase cell membrane potential for adenosine triphosphate (ATP) generation, which enhanced intracellular electron transportation to benefit reactive oxygen species generation. This study provided a new method to enhance microelectrochemical remediation of the contaminant in wetlands via the combination of intermittent air aeration.

Enhanced denitrification and p-nitrophenol removal performance via hydrophilic sponge carriers fixed with dual-bacterial: Optimization, performance, and enhancement mechanism.

Effective treatment of industrial wastewater containing complex pollutants, such as nitrate (NO3--N) and organic pollutants, remains a significant challenge to date. Here, a strain Nocardioides sp. ZS2 with denitrification and degradation of p-nitrophenol (PNP) was isolated and its culture conditions were optimized by kinetic analysis. Hydrophilic sponge carriers were prepared using polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and chitosan (CS) to construct bioreactors. Furthermore, to further enhance the PNP degradation and denitrification performance of bioreactors, Pseudomonas stutzeri GF2 with denitrification capability was introduced. The results revealed that the removal efficiencies of PNP and NO3--N reached 97.9 % and 91.9 %, respectively, when hydraulic retention time (HRT) of 6 h, C/N of 2.0, and pH of 6.5. The bioreactor exhibited stable denitrification performance even with fluctuations in the influent PNP concentration. The potential functional prediction results revealed that the abundance of amino acids, fatty acids, and carbohydrates increased as the influent C/N decreased, reflecting a tendency of the microbial community to adjust carbon source utilization to maintain cell growth, metabolic balance, and resist adverse C/N environments. This research provides new insights into the effective removal of organic pollutants and NO3--N in wastewater treatment.

[Melatonin Enhances the Effect of ABT-737 in Acute Monocytic Leukemia THP-1 Cells].

Melatonin (N-acetyl-5-methoxytryptamine, MEL) is a hormone synthesized by the pineal gland. Due to its oncostatic effect, it can be considered as an antitumor agent and used for combination therapy. ABT-737, a Bcl-2 inhibitor, promotes cell death after treatment with agents that induce pro-apoptotic signals. In the present study, the combined effect of MEL and ABT-737 on changes in proliferative and mitotic activity, mitochondrial membrane potential, intracellular production of reactive oxygen species (ROS), and cytosolic Ca^(2+) was studied. Moreover, changes in the expression of anti- and pro-apoptotic proteins (Bcl-2 and Bax), autophagy markers (LC3A/B (I, II)), endoplasmic reticulum stress markers (chaperones BIP and PDI, CHOP) were studied under these conditions. The effect of MEL together with ABT-737 led to an increase in the level of cytosolic Ca^(2+), intracellular production of ROS and a decrease in the membrane potential of mitochondria. The content of Bcl-2 increased, while the level of Bax decreased. Activation of CHOP stimulated autophagy and led to a decrease in the synthesis of chaperones BIP and PDI. It is assumed that melatonin can enhance the effect of other chemotherapeutic agents and can be used in the treatment of tumors.

Efficient removal of p-nitrophenol from water by imidazolium ionic liquids functionalized cellulose microsphere.

Removing p-nitrophenol (PNP) from water resources is crucial due to its significant threat to the environment and human health. Herein, imidazolium ionic liquids with short/long alkyl chain ([C2VIm]Br and [C8VIm]Br) modified cellulose microspheres (MCC-[C2VIm]Br and MCC-[C8VIm]Br) were synthesized by radiation method. To examine the impact of adsorbent hydrophilicity on adsorption performance, batch and column experiments were conducted for PNP adsorption. The MCC-[C2VIm]Br and MCC-[C8VIm]Br, with an equivalent molar import amount of ionic liquids, exhibited maximum adsorption capacities of 190.84 mg/g and 191.20 mg/g for PNP, respectively, and the adsorption equilibrium was reached within 30 min. Both adsorbents displayed exceptional reusability. Integrating the findings from XPS and FTIR analyses, and AgNO3 identification, the suggested adsorption mechanism posited that the adsorbents engaged with PNP through ion exchange, hydrogen bonds and π-π stacking. Remarkably, the hydrophobic MCC-[C8VIm]Br exhibited superior selectivity for PNP than the hydrophilic MCC-[C2VIm]Br, while had little effect on adsorption capacity and rate. MCC-[C8VIm]Br-2 with high grafting yield increased the adsorption capacity to 327.87 mg/g. Moreover, MCC-[C8VIm]Br-2 demonstrated efficient PNP removal from various real water samples, and column experiments illustrated its selective capture of PNP from groundwater. The promising adsorption performance indicates that MCC-[C8VIm]Br-2 holds potential for PNP removal from wastewater.

Construction of mechanically robust and recyclable catalytic hydrogel based on hydroxypropyl cellulose-supported by montmorillonite/ionic liquid with different anions for pollutants(4-NP, MB, CR, Rhb) degradation.

Dye wastewater poses a serious threat to the environment and human health, necessitating sustainable degradation methods. In this study, Na-based Montmorillonite (MMT) was exfoliated using different ionic liquids ([C16MIM][Cl], [C16MIM][BF4], [C16MIM][PF6]), and silver nanoparticles (Ag NPs) were green-synthesized using hydroxypropyl cellulose (HPC). The HPC significantly enhanced the dispersion of MMT in the hydrogel. By introducing lauryl methacrylate (LMA), a hydrophobic associative network was constructed in PAM/LMA/HPC/MMT@ILs&Ag NPs hydrogel. This hydrogel demonstrated outstanding mechanical properties, with a stress of 833.21 kPa, strain of 3300 %, and toughness of 14.36 MJ/m3. It also exhibited excellent catalytic activity, with a rate constant of 0.83 min-1 for 4-nitrophenol degradation at 28 °C. The effects of temperature and catalyst concentration on the catalytic reaction were systematically investigated. This study presents a simple green synthesis approach for Ag NPs using HPC, achieving superior mechanical performance and stable MMT dispersion in aqueous solutions.

Silver nanoparticle-decorated cellulose beads: Eco-friendly catalysts for efficient 4-nitrophenol reduction and antibacterial performance.

This study presents an innovative and environmentally friendly method to produce fibrous cellulose beads by mechanically stirring natural fibers in an aqueous medium. Date palm fibers are transformed into uniform beads with a diameter of 1.5 to 2 mm through chemical treatment and mechanical agitation. These beads are then decorated with silver nanoparticles (Ag0 NPs) in a one-step synthesis, giving them catalytic capabilities for the reduction of 4-nitrophenol (4-NP) and antibacterial activities. Characterization techniques such as FTIR, XRD, SEM, EDX, and TGA confirmed the successful synthesis and deposition of Ag0 NPs on the cellulose beads. Tests showed complete conversion of 4-NP to 4-AP in just 7 min, with pseudo-first-order kinetics and a Kapp of 0.590 min-1. Additionally, Ag0@CB demonstrated exceptional recyclability and stability over five cycles, with minimal silver release. The beads also showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus, effectively eradicating bacterial colonies in 30 min. In summary, Ag0@CB exhibits multifunctional capabilities for degrading organic pollutants and biomedical applications, offering promising potential for large-scale production and practical use in water treatment and antibacterial coatings.

Nitrophenols in the environment: An update on pretreatment and analysis techniques since 2017.

Nitrophenols, a versatile intermediate, have been widely used in leather, medicine, chemical synthesis, and other fields. Because these components are widely applied, they can enter the environment through various routes, leading to many hazards and toxicities. There has been a recent surge in the development of simple, rapid, environmentally friendly, and effective techniques for determining these environmental pollutants. This review provides a comprehensive overview of the latest research progress on the pretreatment and analysis methods of nitrophenols since 2017, with a focus on environmental samples. Pretreatment methods include liquid-liquid extraction, solid-phase extraction, dispersive extraction, and microextraction methods. Analysis methods mainly include liquid chromatography-based methods, gas chromatography-based methods, supercritical fluid chromatography. In addition, this review also discusses and compares the advantages/disadvantages and development prospects of different pretreatment and analysis methods to provide a reference for further research.

A composite of AgNPs and lignin porous microspheres via in-situ reduction of Ag+ and its catalytic performance.

Despite the widespread utilization of nano silver composites in the domain of catalytic hydrogenation of aromatic pollutants in wastewater, certain challenges persist, including the excessive consumption of chemical reagents during the preparation process and the difficulty in recycling. In this study, silver ions were reduced in-situ by taking advantage of the adsorptive and reducing capacities of hydroxyls and amino groups on lignin porous microspheres (LPMs) under mild ultrasonic conditions, and lignin porous microspheres loaded with silver nanoparticles (Ag@LPMs) were conveniently prepared. Ag@LPMs had excellent catalytic and cycling performances for p-nitrophenol (4-NP), methylene blue (MB) and methyl orange (MO). The 4-NP could be completely reduced to 4-AP within 155 s under the catalysis of Ag@LPMs, with a pseudo-first-order kinetic constant of 1.28 min-1. Furthermore, Ag@LPMs could still complete the catalytic reduction of 4-NP within 10 min after five cycles. Ag@LPMs with the particle size ranging from 100 to 200 µm conferred ease of recycling, and the porous structure effectively resolved the issue of sluggish mass transfer encountered during the catalytic process. At the same time, the binding force of nano silver and LPMs obtained by ultrasonic was stronger than that of heating, so the materials prepared by ultrasonic had better cycling performance. Silver ions concentration and pH value in the preparation process affected the catalytic performance of Ag@LPMs, 50 mmol/L Ag+ and pH value of 7 turned out to be the optimization conditions.

Coupling Peptide-Based Encapsulation of Enzymes with Bacteria for Paraoxon Bioremediation.

The catalytic efficiency of enzymes can be harnessed as an environmentally friendly solution for decontaminating various xenobiotics and toxins. However, for some xenobiotics, several enzymatic steps are needed to obtain nontoxic products. Another challenge is the low durability and stability of many native enzymes in their purified form. Herein, we coupled peptide-based encapsulation of bacterial phosphotriesterase with soil-originated bacteria, Arthrobacter sp. 4Hß as an efficient system capable of biodegradation of paraoxon, a neurotoxin pesticide. Specifically, recombinantly expressed and purified methyl parathion hydrolase (MPH), with high hydrolytic activity toward paraoxon, was encapsulated within peptide nanofibrils, resulting in increased shelf life and retaining ∼50% activity after 132 days since purification. Next, the addition of Arthrobacter sp. 4Hß, capable of degrading para-nitrophenol (PNP), the hydrolysis product of paraoxon, which is still toxic, resulted in nondetectable levels of PNP. These results present an efficient one-pot system that can be further developed as an environmentally friendly solution, coupling purified enzymes and native bacteria, for pesticide bioremediation. We further suggest that this system can be tailored for different xenobiotics by encapsulating the rate-limiting key enzymes followed by their combination with environmental bacteria that can use the enzymatic step products for full degradation without the need to engineer synthetic bacteria.

Determining the esterase activity of peptides and peptide assemblies.

Catalytic peptides are gaining attention as alternatives to enzymes, especially in industrial applications. Recent advances in peptide design have improved their catalytic efficiency with approaches such as self-assembly and metal ion complexation. However, the fundamental principles governing peptide catalysis at the sequence level are still being explored. Ester hydrolysis, a well-studied reaction, serves as a widely employed method to evaluate the catalytic potential of peptides. The standard colorimetric reaction involving para-nitrophenyl acetate hydrolysis acts as a benchmark assay, providing a straightforward and efficient screening method for rapidly identifying potential catalysts. However, maintaining standardized conditions is crucial for reproducible results, given that factors such as pH, temperature, and substrate concentration can introduce unwanted variability. This necessity becomes particularly pronounced when working with peptides, which often exhibit slower reaction rates compared to enzymes, making even minor variations significantly influential on the final outcome. In this context, we present a refined protocol for assessing the catalytic activity of peptides and peptide assemblies, addressing critical considerations for reproducibility and accuracy.

Evaluation of degradation efficacy and toxicity mitigation for 4-nitrophenol using argon and air-mixed argon plasma jets.

This paper investigates the effects of argon (Ar) and that of Ar mixed with ambient air (Ar-Air) cold plasma jets (CPJs) on 4-nitrophenol (4-NP) degradation using low input power. The introduction of ambient air into the Ar-Air plasma jet enhances ionization-driven processes during high-voltage discharge by utilizing nitrogen and oxygen molecules from ambient air, resulting in increased reactive oxygen and nitrogen species (RONS) production, which synergistically interacts with argon. This substantial generation of RONS establishes Ar-Air plasma jet as an effective method for treating 4-NP contamination in deionized water (DW). Notably, the Ar-Air plasma jet treatment outperforms that of the Ar jet. It achieves a higher degradation rate of 97.2% and a maximum energy efficiency of 57.3 gkW-1h-1, following a 6-min (min) treatment with 100 mgL-1 4-NP in DW. In contrast, Ar jet treatment yielded a lower degradation rate and an energy efficiency of 75.6% and 47.8 gkW-1h-1, respectively, under identical conditions. Furthermore, the first-order rate coefficient for 4-NP degradation was measured at 0.23 min-1 for the Ar plasma jet and significantly higher at 0.56 min-1 for the Ar-Air plasma jet. Reactive oxygen species, such as hydroxyl radical and ozone, along with energy from excited species and plasma-generated electron transfers, are responsible for CPJ-assisted 4-NP breakdown. In summary, this study examines RONS production from Ar and Ar-Air plasma jets, evaluates their 4-NP removal efficacy, and investigates the biocompatibility of 4-NP that has been degraded after plasma treatment.

Green construction of self-floating polysaccharide-based hydrogels with catalytic activity for efficient organic pollutants reduction.

This study employed an anionic heteropolysaccharide extracted from overgrown Enteromorpha and homopolysaccharide pullulan to fabricate a self-floating hydrogel by introducing bubble templates. Subsequently, green in-situ reduction and immobilization of silver nanoparticles (Ag NPs) in the hydrogel were successfully achieved without additional reducing agents. The heteropolysaccharide from Enteromorpha provides carboxyl and sulfate groups for Ag+ ions complexation, which is beneficial for the in-situ reduction of Ag NPs and inhibits their aggregation. The incorporation of bubble templates facilitates the creation of a hierarchical pore structure in the hydrogel, giving it self-floating properties for easy recycling, while the hierarchical network with rich anchor sites ensuring adequate traction for Ag NPs dispersion and stabilization. By adjusting polysaccharide content and using bubble templates, Ag NPs smaller than 10 nm can be obtained. The composite hydrogel exhibits tunable catalytic activity and excellent degradation towards Rhodamine B, Methyl Orange, and 4-Nitrophenol, with the normalized rate constant (knor) of 78.89, 59.08, and 30.42 min-1 g-1, respectively. Notably, the reduction efficiency remained above 98 % after 6 recycles with little leaching of Ag NPs, benefiting from its self-floating ability for easy recovery in practical applications.

Hydrazone-linked covalent organic framework functionalized with cysteine as a fluorescence sensor and Exploration of paper chip for p-nitrophenol detection.

The large use and emission of p-nitrophenol (p-NP) seriously pollute the environment and endanger human health. In this work, a hydrazone-linked fluorescent covalent organic framework (BATHz-COF) was simply synthesized at room temperature and covalently linked N-acetyl-L-cysteine (NALC) via the "thiol-ene" click reaction, where carboxyl groups were introduced to improve dispersion and fluorescence intensity. As a rapid, good selectivity and reusability fluorescence sensor, the obtained COF-NALC has been used for quantitative analysis of p-NP predicated on the internal filtering effect (IFE). Under optimal conditions, COF-NALC enabled quantitative detection of p-NP with a linear range of 5-50 µM and the detection limit was 1.46 µM. The application of COF-NALC to the detection of p-NP in river water samples was successful, and the satisfactory recoveries were 98.0%-109.3%. Furthermore, the fluorescent COF paper chips constructed by in situ growth were combined with a smartphone to build a visual platform for the quick and real-time detection of p-NP, providing an excellent illustration for the development of intelligent fluorescence sensing in environmental analysis.

Bioinspired synthesis of multifunctional, highly stable polymeric templated silver-silica colloids as catalytic and antibacterial coatings for paper.

In this paper, a simple, bottom up, bioinspired technique is proposed for the synthesis of highly stable colloids of silica supported spherical silver nanoparticles (SiO2@Ag) that act as efficient catalytic and antimicrobial coatings for an organic substrate, filter paper. The core - shell structure and the highly branched dendritic polymer, poly(ethylene)imine, enabled the precise control of growth rate and morphology of silica and silver nanoparticles. The polymer also enabled the deposition of these nanoparticles onto an organic substrate, filter paper, through immersion by modifying its surface. The catalytic and antibacterial properties of these samples were assessed. The results obtained from this analysis showed a complete degradation of an aqueous pollutant, 4-nitrophenol, for 6 successive catalytic cycles without intermediate purification steps. Furthermore, the polymeric silica-silver suspension proved to express antibacterial activity against both Gram-positive and Gram-negative bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa). The antibacterial properties were evaluated according to the disk diffusion method, whereas the Minimum Inhibitory Concentration was also determined. The samples were examined by Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray diffraction analysis, z-potential analysis, Fourier Transform Infrared Spectroscopy and Ultraviolet-visible Spectroscopy.