Preparation of gold nano-cones as surface-enhanced Raman scattering sensors for molecule detection

Surface-enhanced Raman spectroscopy (SERS) is a powerful novel analytical tool which integrates high levels of sensitivity for trace analysis of chemical and biomolecular species due to the massive enhancement of Raman signals by using nanometre-sized metal particles. However, SERS can be envisaged as an analytical tool only if substrates with strong, predictable and reproducible SERS enhancement can be produced. Here we have developed one simple Ar+ ions sputtering technology to prepare gold nano-cones array on silicon substrates as surface-enhanced Raman scattering (SERS)-active substrates. The tip of the gold cone-structures exhibited an extremely sharp curvature with an apex diameter of 20 nm and the interior apex angle of the nanocones was around 20 degrees. These samples were evaluated as potential SERS substrates using Rhodamine 6G molecules as molecule probe and exhibited SERS enhancement factor of greater than 10, originated from the localized electron field enhancement around the apex of cones and the surface plasmon coupling of periodic structures.     

Electrochemical Characterization of a Porous Pt Nanoparticle ＂Nanocube-Mosaic＂ Prepared by a Modified Polyol Method with HCI Addition

Porous and single crystalline platinum (Pt) nanoparticles (NPs) have been successfully synthesized by reduction of H₂PtCl₆·6H₂O and then investigated by optical spectroscopy and transmission electron microscopy. H₂PtCl₆·6H₂O was reduced using ethylene glycol in the presence of polyvinylpyrrolidone under highly acidic conditions (pH < 1) to form single crystalline Pt particles about 5 nm in size. These particles were then stacked via {100} facets, forming 50-nm length porous nanocubes with a mosaic structure. The porous Pt NPs exhibited excellent catalytic properties for methanol oxidation. In particular, the electrochemical surface area was ∼63 m²/g, five times higher than that for non-porous Pt NPs prepared using a conventional method. We suggest that the high catalytic activity of porous Pt NPs is due to a combination of the crystalline structure having exposed {100} facets and a porous morphology.      

Phylogenetic analysis of atmospheric halotolerant bacterial communities at high altitude in an Asian dust (KOSA) arrival region, Suzu City

The microbial communities transported by Asian desert dust (KOSA) events have attracted much attention as bioaerosols because the transported microorganisms are thought to influence the downwind ecosystems in Korea and Japan. However, the atmospheric microbial community has not been investigated at high altitude in the KOSA arrival area. In this study, to estimate the viability and diversity of atmospheric halotolerant bacteria, which are expected to resist to various environmental stresses as well as high salinities, bioaerosol samples were collected at 10 and 600 m above the ground within the KOSA arrival area, Suzu City, Japan, during KOSA events. During the sampling period, the particle numbers at 600 m were higher than those at 10 m, suggesting that large particles of aerosol fall from the high altitude of 600 m to the ground surface. The microorganisms in bioaerosol samples grew in media containing up to 15% NaCl concentrations demonstrating the viability of the halotolerant bacteria in bioaerosol samples. The PCR-DGGE analysis using 16S rDNA revealed that the bacterial species in NaCl-amended cultures were similar to the bacteria detected from the genomic DNA directly extracted from the bioaerosol samples. The 16S rDNA sequences of bacterial communities in bioaerosol samples were classified into 4 phylotypes belonging to the Bacilluscereus or Bacillussubtilis group. The bioaerosol samples collected at 600 m included 2 phylotypes belonging to B. subtilis, and one phylotype among all 4 phylotypes was identical between the samples at 10 and 600 m. In the atmosphere at 600 m, the halotolerant bacterial community was expected to remain viable, and the species composition was expected to include a few species of the genus Bacillus. During this investigation period, these atmospheric bacteria may have been vertically transported to the ground surface, where the long-range KOSA particle transport from China is frequently observed.     

Mitochondria Turnover and Lysosomal Function in Hematopoietic Stem Cell Metabolism

Hematopoietic stem cells (HSCs) reside in a hypoxic microenvironment that enables glycolysis-fueled metabolism and reduces oxidative stress. Nonetheless, metabolic regulation in organelles such as the mitochondria and lysosomes as well as autophagic processes have been implicated as essential for the determination of HSC cell fate. This review encompasses the current understanding of anaerobic metabolism in HSCs as well as the emerging roles of mitochondrial metabolism and lysosomal regulation for hematopoietic homeostasis.     

Purified Canola Lutein Selectively Inhibits Specific Isoforms of Mammalian DNA Polymerases and Reduces Inflammatory Response

In the screening of DNA polymerase (pol) inhibitor, we isolated lutein, a carotenoid, from the crude (unrefined) pressed oil of canola (low erucic acid rapeseed, Brassica napus L.). Commercially prepared carotenoids such as lutein (1), zeaxanthin (2), β-cryptoxanthin (3), astaxanthin (4), canthaxanthin (5), β-carotene (6), lycopene (7), capsanthin (8), fucoxanthin (9) and fucoxanthinol (10), were investigated for the inhibitory activities of pols. Compounds 1, 2 and 8 exhibited strong inhibition of the activities of mammalian pols β and λ, which are DNA repair- and/or recombination-related pols. On the other hand, all carotenoids tested had no influence on the activity of a mammalian pol α, which is a DNA replicative pol. Lutein (1) was the strongest pol inhibitor of mammalian pols β and λ in the prepared ten carotenoids tested, but did not influence of the activities of mammalian pols α, γ, δ and ε. The tendency for pols β and λ inhibition by these carotenoids showed a positive correlation with the suppression of TPA (12-O-tetradecanoylphorbol-13-acetate)-induced inflammation. These results suggest that cold pressed unrefined canola/rapeseed oil, or other oils with high levels of lutein and other carotenoids, may be useful for their anti-inflammatory properties.     

Initiator‐fragment incorporation radical polymerization of diallyl phthalate: Kinetics,formation of hyperbranched polymer,and iridescent porous film thereof

Diallyl phthalate (DAP) was polymerized in toluene using dimethyl 2,2′‐azobisisobutyrate (MAIB) of high concentrations (0.1–0.9 mol/L) as initiator. The polymerization of DAP of 1.50 mol/L with MAIB of 0.50 mol/L proceeded homogeneously at 80°C without gelation to give soluble polymers in a high yield of 93%. Kinetic results of the homogeneous polymerization at 80°C suggest significant contributions of the degradative chain transfer and the primary radical termination as shown by the rate equation, R_p = k [MAIB]^0.8[DAP]^1.0 (R_p = polymerization rate). The polymer formed in the polymerization of DAP (1.30 mol/L) with MAIB (0.50 mol/L) at 80°C for 8 h consisted of the DAP units with (17 mol %) and without (47 mol %) double bond and the methoxycarbonylpropyl group (36 mol %) as MAIB‐fragment. The large fraction of the incorporated initiator‐fragment as terminal group indicates that the polymer has a hyperbranched structure. The film cast from a solution of the hyperbranched poly(DAP) in tetrahydrofuran showed an iridescent color. The confocal scanning laser microscope image of the film revealed that the iridescent film contained the pores of about 1 μm arranged in an ordered array. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 408–415, 2006     

The CO–H2 and CO–H2O reactions over TiO2 nanotubes filled with Pt metal nanoparticles

We have investigated the catalytic behavior of Pt encapsulated TiO₂ nanotubes for the water gas shift reaction as well as the hydrogenation of CO. Pt–TiO₂ nanotube catalysts were prepared by employing fine fiber shaped crystals of [Pt(NH₃)₄](HCO₃)₂ complex as a structure determining template material. The turnover frequencies (TOF) of these nanotube catalysts were more than one order of magnitude larger than conventional impregnation Pt/TiO₂ catalysts, and the selectivity for methanol in CO–H₂ reaction was extraordinary high compared to the impregnation catalysts. The XPS and XRD analyses of the nanotubes revealed characteristic electronic state of reduced TiO₂ (Ti³⁺ in rutile structure) with zerovalent Pt even after the calcination at 773 K. In WGS reaction, electron rich Ti³⁺ on the nanotube wall may play an important role to activate water molecules for the oxidation of CO. In CO–H₂ reaction, similar promotion effect of Ti³⁺ species may be operating for selective methanol formation by supplying active OH(a).