Quantitative determination of fenoterol and fenoterol derivatives in rat plasma using on-line immunoextraction and liquid chromatography/mass spectrometry

An on-line immunoextraction and liquid chromatography/mass spectrometry (LC/MS) method was developed and validated for the determination of R,R'-fenoterol, R,R'-methoxyfenoterol and R,S'-naphthylfenoterol in rat plasma. Sample preparation involved immunoextraction of analytes using an antibody raised against R,R'- and R,S'-aminofenoterol that was immobilized onto chromatographic support. LC was performed on a Waters hydrophilic interaction chromatography (HILIC) column (150 mm x 2.1mm), using an isocratic mobile phase of methanol:ammonium acetate (10mM, pH 6.8) (90:10, v/v) at a flow rate of 0.2 ml/min. The MS was operated in the single ion monitoring mode (m/z 304.2 for R,R'-fenoterol, m/z 318.1 for R,R'-methoxyfenoterol, and m/z 339.2 for R,S'-naphthylfenoterol). Optimization of analytes desorption process from the immunoextraction column was performed by factorial analysis and the sample calibration curves were made with spiked rat plasma samples containing 0.5-100 ng/ml of drugs. The cross-selectivity studies of the antibody were determined and the results suggested high selectivities toward R,R'-fenoterol, R,R'-methoxyfenoterol and R,S'-naphthylfenoterol. The accuracy of assay was more than 96% while intra- and inter-day precision of assay were less than 12.4%. Stability studies (2h benchtop, freeze/thaw, and autosampler stability) were conducted and the analytes were stable through out studies. The validated method was used to determine the plasma concentration-time profiles of drugs after oral administration to rats of R,R'-fenoterol, R,R'-methoxyfenoterol and R,S'-naphthylfenoterol.     

Biomineralized Multifunctional Magnetite/Carbon Microspheres for Applications in Li‐Ion Batteries and Water Treatment

Advanced functional materials incorporating well‐defined multiscale architectures are a key focus for multiple nanotechnological applications. However, strategies for developing such materials, including nanostructuring, nano‐/microcombination, hybridization, and so on, are still being developed. Here, we report a facile, scalable biomineralization process in which Micrococcus lylae bacteria are used as soft templates to synthesize 3D hierarchically structured magnetite (Fe₃O₄) microspheres for use as Li‐ion battery anode materials and in water treatment applications. Self‐assembled Fe₃O₄ microspheres with flower‐like morphologies are systematically fabricated from biomineralized 2D FeO(OH) nanoflakes at room temperature and are subsequently subjected to post‐annealing at 400 °C. In particular, because of their mesoporous properties with a hollow interior and the improved electrical conductivity resulting from the carbonized bacterial templates, the Fe₃O₄ microspheres obtained by calcining the FeO(OH) in Ar exhibit enhanced cycle stability and rate capability as Li‐ion battery anodes, as well as superior adsorption of organic pollutants and toxic heavy metals.     

Nonenzymatic amperometric sensor for ascorbic acid based on hollow gold/ruthenium nanoshells

We report a new nonenzymatic amperometric detection of ascorbic acid (AA) using a glassy carbon (GC) disk electrode modified with hollow gold/ruthenium (hAu–Ru) nanoshells, which exhibited decent sensing characteristics. The hAu–Ru nanoshells were prepared by the incorporation of Ru on hollow gold (hAu) nanoshells from Co nanoparticle templates, which enabled AA selectivity against glucose without aid of enzyme or membrane. The structure and electrocatalytic activities of the hAu–Ru catalysts were characterized by spectroscopic and electrochemical techniques. The hAu–Ru loaded on GC electrode (hAu–Ru/GC) showed sensitivity of 426 μA mM⁻¹ cm⁻² (normalized to the GC disk area) for the linear dynamic range of <5 μM to 2 mM AA at physiological pH. The response time and detection limit were 1.6 s and 2.2 μM, respectively. Furthermore, the hAu–Ru/GC electrode displayed remarkable selectivity for ascorbic acid over all potential biological interferents, including glucose, uric acid (UA), dopamine (DA), 4-acetamidophenol (AP), and nicotinamide adenine dinucleotide (NADH), which could be especially good for biological sensing.     

Irreversible inhibition of CD13/aminopeptidase N by the antiangiogenic agent curcumin

CD13/aminopeptidase N (APN) is a membrane-bound, zinc-dependent metalloproteinase that plays a key role in tumor invasion and angiogenesis. Here, we show that curcumin, a phenolic natural product, binds to APN and irreversibly inhibits its activity. The direct interaction between curcumin with APN was confirmed both in vitro and in vivo by surface plasmon resonance analysis and an APN-specific antibody competition assay, respectively. Moreover, curcumin and other known APN inhibitors strongly inhibited APN-positive tumor cell invasion and basic fibroblast growth factor-induced angiogenesis. However, curcumin did not inhibit the invasion of APN-negative tumor cells, suggesting that the antiinvasive activity of curcumin against tumor cells is attributable to the inhibition of APN. Taken together, our study revealed that curcumin is a novel irreversible inhibitor of APN that binds to curcumin resulting in inhibition of angiogenesis.     

Benzimidazole-based imine-linked chemosensor: chromogenic sensor for Mg2+ and fluorescent sensor for Cr3+

We synthesized an imine-linked, benzimidazole-based chemosensor that can be used for chromogenic recognition of Mg²⁺ and fluorescent recognition of Cr³⁺. The chemosensor shows sensitive, selective, and ratiometric recognition of Cr³⁺ through concurrent quenching at one wavelength and enhancement of fluorescence intensity at another wavelength. It can also be used to detect Mg²⁺ via UV–vis absorption spectroscopy. DFT calculations support these phenomena. The sensor can be used to strain microbe cells without breakage.     

Nonspecific association of 2',3'-cyclic nucleotide 3'-phosphodiesterase with the rat forebrain postsynaptic density fraction

The 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), a protein of unknown function in vivo, is abundantly expressed in myelinating glia in two isoforms, CNP1 and CNP2. In this study, immunoblot analysis showed that CNP1 is the major isoform in adult forebrain, and that both isoforms are included in the postsynaptic density (PSD) fraction and tyrosine-phosphorylated at the basal level. However, subcellular distribution and detergent extraction data showed that CNP is nonspecifically associated with the PSD fraction. Immunocytochemistry revealed that CNP is detected, in a weak but punctate pattern, in dissociated rat hippocampal neurons of 3 days to 2 weeks in vitro. The CNP-positive punctae were distributed throughout soma and dendrites, and distinct from PSD95-positive ones. Immunoblot analysis indicated that CNP is also expressed in neuronal stem cell lines, HiB5 and F11. Interestingly, in addition to the known two isoforms, a new CNP isoform of MW 45 kDa was expressed in these cell lines and was the major type of isoform in F11 cells. Taken together, our data suggest that CNP is expressed in the early stage of in vitro development and nonspecifically included in the adult rat PSD fraction.     

Graphene Nanosheets as a Platform for the 2D Ordering of Metal Oxide Nanoparticles: Mesoporous 2D Aggregate of Anatase TiO2 Nanoparticles with Improved Electrode Performance

Graphene nanosheets are successfully applied as an effective platform for the 2D ordering of metal oxide nanoparticles. Mesoporous 2D aggregates of anatase TiO₂ nanoparticles are synthesized by the heat treatment of the uniformly hybridized nanocomposite of layered titanate–reduced graphene oxide (RGO) at elevated temperatures. The precursor layered titanate–RGO nanocomposite is prepared by self‐assembly of anionic RGO nanosheets and cationic TiO₂ nanosols. The calcination of the as‐prepared layered titanate–RGO nanocomposite at 500 °C induces a structural and morphological change of layered titanate nanoplates into anatase TiO₂ nanoparticles without significant modification of the RGO nanosheet. Increasing the heating temperature to 600 °C gives rise to elimination of the RGO component, leading to the formation of sheetlike porous aggregates of RGO‐free TiO₂ nanoparticles. The nanocomposites calcined at 500–700 °C display promising functionality as negative electrodes for lithium ion batteries. Among the present calcined derivatives, the 2D sheet‐shaped aggregate of TiO₂ nanoparticles obtained from calcination at 600 °C delivers the greatest specific discharge capacity with good capacity retention for all current density conditions applied. Such superior electrode performance of the nanocomposite calcined at 600 °C is attributable both to the improved stability of the crystal structure and crystal morphology of titania and to the enhancement of Li⁺ ion transport through the enlargement of mesopores. The present findings clearly demonstrate the usefulness of RGO nanosheets as a platform for 2D‐ordered superstructures of metal oxide nanoparticles with improved electrode performance.     

Determination of the radon emanation fraction from phosphogypsum using LSC

A simple method for the determination of the radon emanation fraction was studied using a liquid scintillation counter. The radon activity of the gaseous phase in a closed container was measured 1 day and 35 days after sealing and used to calculate the radon emanation fraction. Radon leakage from the container was investigated using a ²²⁶Ra radioactive standard solution (SRM4967, NIST) to plot a radon growth curve. The method was applied to materials that typically contain a high level of radium, such as phosphogypsum, phosphate fertilizer and a rock sample. The effect of temperature on the radon emanation fraction from the materials was investigated at 0, 10, 20, 30 and 40 °C. It was found that there is a linear correlation (R ² = 0.746 − 0.946) between temperature and the emanation fraction. Within the temperature range, the radon emanation fractions were 0.241–0.466 for phosphogypsum, 0.225–0.351 for phosphate fertilizer and 0.154–0.351 for the rock sample.     

Selective ethylene trimerization with a cyclopentadienyl-arene titanatrane catalyst

Cyclopentadienyl-arene titanatrane catalysts activated by methylaluminoxane (MAO) cocatalysts were studied for the trimerization of ethylene. The introduction of electron-rich multidentate ligands to the catalysts?? active sites resulted in good productivity and selectivity for ethylene trimerization. Various amounts of MAO were tested, and methods of its introduction to the system were varied. It has been shown that pre-alkylation of the catalyst with MAO increases the productivity of ethylene trimerization. The effects of reaction temperature and pressure on 1-hexene productivity and selectivity were also studied. The rate of ethylene conversion was approximately first order with respect to ethylene concentration. 1-Hexene was produced under moderate conditions, allowing energy savings to be gained through lower temperature reactions.