Selective stepwise adsorption for enhanced removal of multi-component dissolved organic chemicals from petrochemical wastewater.

The coexistence of multi-component dissolved organic chemicals causes tremendous challenge in purifying petrochemical wastewater, and stepwise selective adsorption holds the most promise for enhanced treatments. This study is designed to enhance the removal of multiple dissolved organic chemicals by stepwise adsorption. Special attention is given to the selective removal mechanisms for the major pollutant N,N-dimethylformamide (DMF), the sensitive pollutant fluorescent dissolved organic matter (FDOM) and other components. The results indicated that the combination of coal activated carbon and aluminum silica gel produced a synergistic effect and broke the limitation of removing only certain pollutants. Combined removal rates of 80.5 % for the dissolved organic carbon and 86.7 % for the biotoxicity in petrochemical wastewater were obtained with the enhanced two-step adsorption. The adsorption performance of both adsorbents remained stable even after five cycles. The selective adsorption mechanism revealed that hydrophobic organics such as DMF was adsorbed by the macropores of coal activated carbon, while the FDOM was eliminated by π-π stacking, electrostatic interaction and hydrophobic interaction. The hydrophilic organics were removed by the mesopores of aluminum silica gel, the silica hydroxyl groups and hydrophilic interaction. This study provides a comprehensive understanding of the selective adsorption mechanism and enhanced stepwise removal of multiple pollutants in petrochemical wastewater, which will guide the deep treatment of complex wastewater.

Synthesis and Characterization of Compounds Based on Carbazole and Sulfone Groups.

Two compounds containing carbazole and sulfone groups with different alkyl chain lengths have been designed and synthesized. The sulfone group has strong absorption characteristics and the alkoxy chain and carbazole group are electron-rich, forming D-δ-A-type symmetrical molecules. The molecules have the characteristics of charge transfer and high thermal stability, and the molecules stack to form a layered staggered stack, reducing the intermolecular π-π interactions. The target compounds also exhibit strong ultraviolet-fluorescent emission in the solid state at room temperature, and they are expected to be good luminescent materials.

Facile synthesis of N-doped carbon nanoframes encapsulated by CoP nanoparticles for hydrogen evolution reaction.

Development of high-performance, economic, and stable non-noble metal catalysts is a still formidable challenge in hydrogen evolution reaction (HER) that must be overcome to alleviate the energy and environmental crisis. Herein, we designed and fabricated N-doped carbon nanoframes encapsulated by CoP nanoparticles (CoP-NCN). The 3D porous structure of the ZIF-67-derived N-doped carbon shortened the charge and mass transport pathways, contributing to enhanced electrocatalytic performance. Moreover, the synergistic effects of excellent conductivity, abundant mesopores, and high-activity CoP nanoparticles led to remarkable electrocatalytic activity toward HER with an extremely low overpotential of 120 mV at 10 mA cm-2 and long-term stability. We further indicate that the fantastic HER catalytic ability of CoP-NCN is attributed to the good conductivity and the abundant active sites. The present study provides a promising avenue toward the design of cost-effective HER electrocatalysts.

Epoxy-functionalized macroporous carbon with embedded platinum nanoparticles for electrochemical detection of telomerase activity via telomerase-triggered catalytic hairpin assembly.

Telomerase is regarded as a crucial biomarker for the early diagnosis of malignant tumors and a valuable therapeutic target. In this work, a telomerase-triggered amplification strategy was designed on the basis of a catalyzed hairpin assembly (CHA) for bridging a signal probe of platinum nanoparticles (Pt NPs) anchored on three-dimensional (3D) epoxy-functionalized macroporous carbon (Pt/MPC-COOH) in an ultrasensitive electrochemical biosensor. Pt/MPC-COOH nanomaterials with interconnected macroporous structure not only immobilized hairpin DNA probe 2 (H2) via an amide reaction (Pt/MPC-COOH-H2), but they also generated an obvious electrochemical signal in response to acetaminophen (AP) oxidation. After the introduction of telomerase, telomerase primer (TP) was extended to a telomerase extension product (TEP) with several hexamer repeats (TTAGGG)n to initiate the CHA cycle, leading to signal amplification. Subsequently, with the TEP-triggered CHA cycle amplification strategy, a large amount of Pt/MPC-COOH-H2 was introduced on the electrode surface for the construction of the electrochemical platform, which realized the sensitive detection of telomerase activity from 102 to107 cells mL-1 with a limit of detection (LOD) of 9.02 cells mL-1. This strategy provides a sensitive method for the detection of biomolecules that could be useful for bioanalysis and early clinical diagnoses of diseases.

Facile preparation of Ni nanoparticle embedded on mesoporous carbon nanorods for non-enzymatic glucose detection.

Transition metal doped carbon materials are recognized as promising sensing platforms for glucose detection. Herein, a simple strategy involving crystallinity, nanostructure engineering, and pyrolysis was developed for constructing well-defined Ni nanoparticle embedded on nanoporous carbon nanorods (Ni/NCNs). A three-dimensional nickel-based metal-organic framework (Ni-MOF) was used as both a self-sacrificing template and precursor. Due to the synergistic effects between the uniformly dispersed Ni nanoparticles and the nanoporous carbon matrix, the as-prepared Ni/NCNs exhibited remarkable electrochemical activity. The fabricated Ni/NCNs glucose sensor showed excellent electrocatalytic performance with ultra-low limit of detection, wide linear detection ranges, fast response times (within 1.6 s), superior stability, and anti-interference characteristics. Moreover, the Ni/NCNs sensing platform was successfully applied to analyze glucose concentrations in human blood samples. These results showed that Ni/NCNs hold potential applications in developing enzyme-free glucose sensors.

A novel cobalt and nitrogen co-doped mesoporous hollow carbon hemisphere as high-efficient electrocatalysts for oxygen reduction reaction.

Exploring a cheap catalyst with effective activity for oxygen reduction reaction (ORR) to replace precious metal electrocatalysts has gained tremendous attention for several decades. In this study, we designed and synthesized cobalt and nitrogen supported on mesoporous hollow carbon hemisphere (Co/N/HCHs) nanocomposites by a facile and economical approach. Semisphere-shaped mesoporous hollow carbon is self-generated using silica particles as template, followed by a pyrolysis-etching process; and exhibits high electrical conductivity and high specific surface. The unique porous structure of carbon provides significant number of the abundant defective sites and shortens the mass transfer pathway, leading to a greatly enhanced electrocatalytic activity with mainly 4e- reduction. Moreover, the synergistic effects of large electrochemically active areas and good electrical conductivity, resulting from the introduction of Co and N heteroatom, are the main reason for displaying outstanding ORR activity with a high half-wave potential of 0.8 V and the electron transfer numbers of 3.89. Furthermore, an excellent long-term stability (the current density retention of 87.0%) and superb methanol tolerance in alkaline medium are achieved. Undoubtedly, this demonstrates a potential way to strategically design the non-precious metal doped carbon catalysts for wider practical applications.

Preparation of Pt anchored on cerium oxide and ordered mesoporous carbon tri-component composite for electrocatalytic oxidation of adrenaline.

The preparation of Pt/cerium oxide and highly ordered mesoporous carbon (Pt/CeO2/OMC) nanohybrids is reported. CeO2 can be used as an active material that enhances the electrocatalytic properties of Pt nanoparticles. OMC exhibits excellent electrical conductivity and large specific surface area, which makes it a highly promising electrocatalyst support. Benefiting from the synergistic effects of the catalytic performance of Pt/CeO2 and excellent conductivity of OMC supports, the new nanocomposite of Pt/CeO2/OMC are able to create novel features of electrocatalytic activities. Pt/CeO2/OMC tri-component composite was used as an excellent sensing platform for the determination of adrenaline. The developed sensor exhibited excellent activity and convincing analytical performance towards adrenaline, such as wide linear range, high sensitivity, low limit of detection, and low limit of quantification. In addition, the recoveries ranging from 93.4 to 103.6% were obtained in human serum samples. The successful preparation of Pt/CeO2/OMC tri-component composite may promote the development of novel electrocatalyst and facilitate the design of new electrochemical sensors.

Facile preparation of CoMoO4 nanorods at macroporous carbon hybrid electrocatalyst for non-enzymatic glucose detection.

Glucose is a popular biosensor target due to its closely with diabetes or hypoglycemia in blood. Designing efficiency electrocatalysts for the determination of glucose is vital to develop glucose detection devices. CoMoO4, as a kind of bimetallic oxide material, exhibits unique electrochemical properties. 3D macroporous carbon (MPC) has large specific surface area and excellent electrical conductivity, providing an effective support for loading other nano-entities to form novel composite with good synergetic effects. Herein, nanorod-like CoMoO4 anchored onto MPC support was synthesized for the development of a promising electrochemical sensing platform for glucose. Attributing to the synergic effects between the good electrocatalytic performance of CoMoO4 nanorods and the extraordinary electrical conductivity of 3D layered MPC, the novel CoMoO4/MPC composites non-enzymatic sensor shows excellent electrocatalytic performance for oxidation of glucose. Under the optimum conditions, the proposed CoMoO4/MPC hybrids provided a reliable linear range of 5 × 10-7 to 1.08 × 10-4 M with a low limit of detection (0.13 µM) for the detection of glucose. Meanwhile, the CoMoO4/MPC sensing platform shows fast response time of 1.76 s, good stability and selectivity for detecting glucose. Moreover, this non-enzymatic sensor also has been successfully applied to measure glucose level in human blood samples. Therefore, the developed sensor holds a new promise for the construction of facile and sensitive non-enzymatic glucose analytical platform.

An enzyme-free electrochemical biosensor based on well monodisperse Au nanorods for ultra-sensitive detection of telomerase activity.

Efficient platforms for detecting telomerase activity are essential for early tumor monitoring and diagnosis. Herein, an enzyme-free electroanalytical strategy was developed for reliable and highly sensitive telomerase activity assay based on the increased electrochemical signals of methylene blue (MB) catalyzed by well monodisperse Au nanorods (AuNRs). In the presence of dNTPs and telomerase extracts, the assistant DNA 1 in the double stranded DNA can be extended to telomere repeat units (TTAGGG)n, which could form a hairpin structure by telomerase-triggered extension. The assistant DNA 2 was ingeniously dissociated from the double stranded DNA to combine with capture DNA. As a result, a large amount of AuNRs could be anchored on the surface of these sequences and used for electrocatalytic oxidation of MB. The developed biosensor showed a low limit of detection of 8.20 HeLa cells mL-1 and a wide dynamic range from 30 to 1.04 × 107 HeLa cells mL-1 for the determination of telomerase activity, which can provide a new way for telomerase activity assays in early diagnosis for cancers.

Facile synthesis of Fe, Co bimetal embedded nanoporous carbon polyhedron composites for an efficient oxygen evolution reaction.

The development of highly efficient, stable, and low-cost non-noble-metal electrocatalysts for oxygen evolution reactions (OER) is a major challenge for facilitate the efficiency of green energy storage. Bimetallic oxides are considered promising candidates as the electrocatalysts for OER because of their remarkable electrocatalytic activity, good stability, and low cost. In this work, ZIF-67 precursors were prepared via microwave irradiation and used as a self-sacrificing template. We proposed a rapid and scalable strategy to prepare Fe, Co bimetal embedded nanoporous carbon (Fe-Co/NPC) polyhedron composites by thermal decomposition of Fe species incorporated ZIF-67 precursor. Benefiting from the distinctive 3D polyhedron structural and compositional advantages, Fe-Co/NPC with hierarchical porous structure showed excellent electrochemical performance as ideal electrode material for OER. The resulting Fe-Co/NPC displayed outstanding electrocatalytic activity for OER with appreciable onset potential (1.59 V (vs. RHE)), small Tafel slope (53.55 mV dec-1), low over-potential (396 mV) to reach 10 mA cm-2, and excellent durability with negligible loss in current density after 1000 cycles. The current work demonstrated new insight into the design and construction of 3D structured Fe-Co/NPC polyhedron catalysts with highly electrocatalytic activity and good stability for electrocatalysis applications.

Electrochemical study of hydrazine oxidation by leaf-shaped copper oxide loaded on highly ordered mesoporous carbon composite.

Hydrazine is a possible human carcinogen because of its hyper toxicity. Therefore, the determination of hydrazine is particularly important for environmental protection and public security. Electrochemical method for the detection of hydrazine has drawn great interests because of its high sensitivity, fast response time, simple operation, and low cost. In this work, a leaf-like copper oxide (CuO) anchored onto wormlike ordered mesoporous carbon (OMC) composite was prepared for the construction of an electrochemical sensing platform for hydrazine. Because of the synergetic catalytic effect and unique structural properties, the obtained nanosized CuO incorporated in OMC exhibited good electrocatalytic performance for the oxidation of hydrazine with a catalytic rate constant (kcat) of 1.28 × 105 M-1s-1. Moreover, the content ratio of CuO: OMC was optimized to improve the electrocatalytic performance. The CuO/OMC hybrids can act as a sensitive and effective sensing platform for the determination of hydrazine, exhibiting wide linear range, high sensitivity, low limit of detection, and good stability. This comprehensive and systematic study may provide great opportunities for the design and construction of electrochemical sensors for environmental monitoring.

The role of adenosine in up-regulation of p38 MAPK and ERK during limb ischemic preconditioning-induced brain ischemic tolerance.

Our previous studies have demonstrated that limb ischemic preconditioning (LIP) induced brain ischemic tolerance and up-regulated the expression of p38 MAPK and ERK in the hippocampal CA1 region in rats. The present study was undertaken to investigate the role of adenosine in brain protection and up-regulation of p38 MAPK and ERK induced by LIP. It was found that adenosine A1 receptor antagonist DPCPX dose-dependently inhibited the protective effect of LIP. The up-regulation of p38 MAPK and ERK induced by LIP could be blocked by DPCPX. Furthermore, we observed the effect of adenosine on the brain ischemia. The results showed that pre-administration of adenosine could partly mimic the neuroprotective effect on the brain, up-regulate the expression of p38 MAPK and ERK. Based on the above results, it can be concluded that adenosine participated in brain protection and up-regulation of the expression of p38 MAPK and ERK during the induction of brain ischemic tolerance after LIP.

A label-free electrochemical biosensor for ultra-sensitively detecting telomerase activity based on the enhanced catalytic currents of acetaminophen catalyzed by Au nanorods.

An electrochemical biosensor was designed for the determination of telomerase activity using an enzyme-free, PCR-free, and convenient electrochemical strategy. In this work, the electrochemical biosensor was constructed through the functionalization of Au nanorods with a carboxylic group (AuNRs-3) and subsequent immobilization with capture DNA (cDNA) for sensing telomerase activity. Upon telomerase triggered extension, the telomerase activity is related to the amount of the adsorbed electrocatalyst, leading to the different electrochemical signals for readout. Integrating with the efficient electrocatalysis of AuNRs-3-cDNA towards oxidation of acetaminophen, the prepared biosensor exhibits a wide dynamic correlation of telomerase activity from 1 × 102 to 1.04 × 107 HeLa cells mL-1 with a sensitivity of 2.68 HeLa cell mL-1 and the limit of detection was calculated to be 52.81 HeLa cells mL-1 under the optimal experimental conditions. Furthermore, the application of this electrochemical biosensor would provide the great potential for analysis of telomerase activity, revealing a powerful platform for early diagnosis of cancers.

Facile synthesis of platinum-embedded zirconia/porous carbons tri-component nanohybrids from metal-organic framework and their application for ultra-sensitively detection of methyl parathion.

Pt nanoparticles immobilized on zirconium oxide (ZrO2) and porous carbons (Pt/ZrO2/PCs) tri-component nanohybrids derived from Pt/ metal-organic frameworks (MOFs) were synthesized. They were prepared by using Pt/MOFs as a template. Additionally, MOFs (UiO-66, a traditional MOFs) were used as ZrO2 and carbon sources without the need of additional precursors. The formation of these composite materials was confirmed through a comprehensive characterization such as transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The Pt/ZrO2/PCs show strong affinity toward the phosphate group and highly electrocatalytic activity for nitro compound on methyl parathion (MP) molecules. The high performance is owing to the combination of unique electrocatalytic activity of Pt species, excellent conductivity of PCs, and good adsorption properties of ZrO2 crystals for MP. The proposed Pt/ZrO2/PCs tri-component nanocomposite sensor realized the ultrasensitive detection of MP with a wide linear range between 3.8 × 10-9 and 1.14 × 10-2 mM and a low limit of detection of 1.45 × 10-9 mM. Therefore, it can be developed as an effective sensing platform for the detection of MP.

Facile synthesis of Au-embedded porous carbon from metal-organic frameworks and for sensitive detection of acetaminophen in pharmaceutical products.

Here we report an Au nanoparticles supported on nanostructured porous carbon (NPCs) hybrid through a coordination-assisted strategy. Metal-organic frameworks (MOFs) have been demonstrated as suitable precursors for preparing NPCs through the impregnation of a secondary carbon source within pores of MOFs. The thermal transformation of Au/UiO-66-NH2 composites in an inert atmosphere has yielded ultrafine Au-embedded NPCs (Au/NPCs). The formation of these composite materials was verified by a comprehensive characterization using X-ray diffraction, N2 adsorption, scanning electron microscopy, and transmission electron microscopy. Because of the unique structural properties and synergetic catalytic effect, Au/NPCs can be developed as an effective sensing platform for the detection of acetaminophen (AP), which showed high activity and excellent analytical performance towards AP, such as a wide linear range of 0.12-95.10 µM, a high sensitivity of 357.62 µA mM-1, and a low limit of detection of 49.4 nM. Importantly, the successfully fabricated Au/NPCs device accurately measured the amount of AP in pharmaceutical samples.

A Simple and Rapid Fluorescent Probe for Detection of Cr3+ Based on a Coumarin Schiff Base in Aqueous Solution.

A new Cr3+ probe was synthesized using simple Schiff base reaction, which showed prominent fluorescence increasing switch before and after addition Cr3+. The probe proved to have excellent properties, based on both UV-vis absorption and fluorescence spectra. Those properties included high switching performance, good selectivity, and small interference with other metal ions. The fluorescent change mechanism of the probe was attributed to the combined action between the restricted C=N isomerization and the suppression of highly efficient photo-induced electron transfer (PET) process. Moreover, this fluorescence probe for Cr3+ detection also has great potential for bioimaging of cancer cells.

[Effect of limb ischemic preconditioning on the expression of p38 MAPK and HSP 70 in CA3 and DG regions of the hippocampus of rats].

OBJECTIVE: To observe the expression of p38 MAPK and HSP 70 in CA3 and dentate gyrus (DG) regions of the hippocampus of rats induced by limb ischemic preconditioning (LIP). METHODS: Ninety-six rats were randomly divided into sham and LIP groups. And the animals in the LIP group were further divided into LIP 6 h, LIP 12 h, LIP 1 d, LIP 2 d, LIP 3 d, LIP 4 d and LIP 5 d subgroups according to the time of reperfusion after LIP. Immunohistochemical staining and Western blot were used to observe the expression of p38 MAPK and HSP 70 in CA3 and DG regions of the hippocampus. RESULTS: The results of the immunohistochemical staining and Western blot were consistent, which indicated that there were fluctuation in the p-p38 MAPK and HSP 70 expression in CA3 and DG regions after LIP compared with those of the sham group. The expression of p-p38 MAPK began to be up-regulated 1d after LIP and reached its peak at 3 d and lasted for 4 d after LIP. However, the expression of HSP 70 was significantly up-regulated 2 d after LIP compared to the sham group, reached its peak at 3 d and lasted until the 4 d after LIP. CONCLUSION: LIP up-regulates the expression of p38 MAPK and HSP 70 in the CA3 and DG regions of the hippocampus of rats.