Pt‐Nanoparticle Incorporated Carbon Paste Electrode for the Determination of Cu(II) Ion by Anodic Stripping Voltammetry

Pt‐nanoparticles were synthesized and introduced into a carbon paste electrode (CPE), and the resulting modified electrode was applied to the anodic stripping voltammetry of copper(II) ions. The synthesized Pt‐nanoparticles were characterized by cyclic voltammetry, scanning electron microscopy and X‐ray photoelectron spectroscopy techniques to confirm the purity and the size of the prepared Pt‐nanoparticles (ca. 20 nm). This incorporated material seems to act as catalysts with preconcentration sites for copper(II) species that enhances the sensitivity of Cu(II) ions to Cu(I) species at a deposition potential of ?0.6 V in an aqueous solution. The experimental conditions, such as, the electrode composition, pH of the solution, pre‐concentration time, were optimized for the determination of Cu(II) ion using as‐prepared electrode. The sensitivity changes on the different binder materials and the presence of surfactants in the test solution. The interference effect of the coexisted metals were also investigated. In the presence of surfactants, especially TritonX‐100, the Cu(II) detection limit was lowered to 3.9×10^?9 M. However, the Pt‐nanoparticle modified CPE begins to degrade when the period of deposition exceeds to 10 min. Linear response for copper(II) was found in the concentration range between 3.9×10^?8 M and 1.6×10^?6 M, with an estimated detection limit of 1.6×10^?8 M (1.0 ppb) and relative standard deviation was 4.2% (n=5).     

A facile synthesis of polypyrrole nanotubes using a template-mediated vapor deposition polymerization and the conversion to carbon nanotubes

Polypyrrole (PPy) nanotubes with highly uniform surface and tunable wall thickness were fabricated by one-step vapor deposition polymerization (VDP) using anodic aluminium oxide (AAO) template membranes, and transformed into carbon nanotubes through a carbonization process.     

Chemical Speciation of Amphoteric Ions on Semi‐Dry Scrubber Residue and Bag‐House Ash from MSWI

Two series of size‐fractionated combusted residues, a bag‐house ash and a scrubber residue, from a municipal solid waste incinerator (MSWI) were prepared and extracted by means of sequential chemical extraction (SCE) procedures proposed by Tessier. Concentrations of water‐soluble phase, exchangeable phase, carbonated phase, Fe/Mn oxide phase, organic matter phase, and residual phase bound amphoteric metals (Pb and Zn) were obtained, and have been compared with those of single batch extraction of toxic characteristic leaching procedure (TCLP). In each size fraction of baghouse ash or scrubber residue, lead or zinc shows a common phenomena that the TCLP value is always lower than the content of the water‐soluble fraction. For lead, baghouse ash has a significant size‐dependent distribution on the water‐soluble phase to perform a size‐dependent test of lead in the TCLP test. The zinc TCLP data having less size dependence might be due to that neither the baghouse ash nor the scrubber residue has a size‐dependent distribution on the water‐soluble zinc phase.     

Profiling surface glycans on live cells and tissues using quantum dot-lectin nanoconjugates

The surface of mammalian cells is densely coated with complex glycans, which are directly involved in cell-cell or cell-protein interactions that trigger various biological responses. Here, we present a novel glycomics approach that uses quantum dot (Qdot)-lectin nanoconjugates to interrogate the surface glycans of tissues and patterned cells. Our approach allows highly sensitive in situ monitoring of specific lectin-glycan interactions and quantitative information on surface glycans for each examined cell line and tissue. The results clearly show significant changes in glycosylation for each cell line and tissue sample. We expect that these results will be applicable in cancer diagnostics and promote the development of new analytical tools for glycomics.     

Platinum-catalyzed diastereoselective intramolecular coupling of allyl halides and hydrazones

Nucleophilic allyl platinum addition to hydrazones under platinum-catalyzed conditions was studied. To generate nucleophilic allyl platinum complexes, allyl halides were employed with platinum complexes, SnCl(2), and H(2). The allyl platinum(IV) intermediates reacted with the hydrazone to give the corresponding cyclic amine derivatives in good yield and with excellent diastereoselectivity. The cis selectivity of N-tethered substrates was attributed to a tight interaction of allyl platinum species with the hydrazone, on the basis of the results of solvent screening and acid/base addition experiments.     

Anthocyanins protect against A2E photooxidation and membrane permeabilization in retinal pigment epithelial cells

The pyridinium bisretinoid A2E, an autofluorescent pigment that accumulates in retinal pigment epithelial cells with age and in some retinal disorders, can mediate a detergent-like perturbation of cell membranes and light-induced damage to the cell. The photodynamic events initiated by the sensitization of A2E include the generation of singlet oxygen and the oxidation of A2E at carbon-carbon double bonds. To assess the ability of plant-derived anthocyanins to modulate adverse effects of A2E accumulation on retinal pigment epithelium (RPE) cells, these flavylium salts were isolated from extracts of bilberry. Nine anthocyanin fractions reflecting monoglycosides of delphinidin, cyanidin, petunidin and malvidin were obtained and all were shown to suppress the photooxidation of A2E at least in part by quenching singlet oxygen. The anthocyanins tested exhibited antioxidant activity of variable efficiency. The structural characteristics relevant to this variability likely included the ability to form a stable quinonoidal anhydro base at neutral pH, a conjugated diene structure in the C (pyrane) ring, the presence of hydroxyl groups on the B (benzene) ring and the relative hydrophobicity conferred by the arrangement of substituents on the B ring. Cells that had taken up anthocyanins also exhibited a resistance to the membrane permeabilization that occurs as a result of the detergent-like action of A2E.     

Degradation of polystyrene using montmorillonite clay catalysts

Summary The performance of acid-treated montmorillonite catalysts in the degradation of polystyrene (PS) was investigated in this study. The degradation was carried out in a semi-batch reactor with a mixture of PS and catalyst at 400-450^oC. The commercial Süd Chemie acid-treated montmorillonite clays (K-series) showed good catalytic activity for the degradation of PS. The styrene monomer and ethylbenzene were major liquid products. The increase of surface acidity enhanced further cracking of styrene dimer and trimer to produce styrene monomer. Higher production of ethylbenzene for K30 may be related to its bigger pore volume and surface area compared to those of K5. High degradation temperature favored styrene monomer production.     

Platinum-free tungsten carbides as an efficient counter electrode for dye sensitized solar cells

Mesoporous tungsten carbides displayed an excellent solar conversion efficiency (7.01%) as a counter electrode for dye sensitized solar cells under 100 mW cm(-2), AM 1.5G illumination, which corresponded to ca. 85% of the efficiency of the conventional platinum electrode.     

Mutant-Selective Allosteric EGFR Degraders are Effective Against a Broad Range of Drug-Resistant Mutations

Targeting epidermal growth factor receptor (EGFR) through an allosteric mechanism provides a potential therapeutic strategy to overcome drug-resistant EGFR mutations that emerge within the ATP binding site. Here, we develop an allosteric EGFR degrader, DDC-01-163, which can selectively inhibit the proliferation of L858R/T790M (L/T) mutant Ba/F3 cells while leaving wildtype EGFR Ba/F3 cells unaffected. DDC-01-163 is also effective against osimertinib-resistant cells with L/T/C797S and L/T/L718Q EGFR mutations. When combined with an ATP-site EGFR inhibitor, osimertinib, the anti-proliferative activity of DDC-01-163 against L858R/T790M EGFR-Ba/F3 cells is enhanced. Collectively, DDC-01-163 is a promising allosteric EGFR degrader with selective activity against various clinically relevant EGFR mutants as a single agent and when combined with an ATP-site inhibitor. Our data suggests that targeted protein degradation is a promising drug development approach for mutant EGFR.