Enhanced enzyme activity and enantioselectivity of lipases in organic solvents by crown ethers and cyclodextrins

Lipases from Candida rugosa (CRL) and Pseudomonas cepacia (PCL) were co-lyophilized with cyclic oligoethers including four crown ethers and nine cyclodextrins (CyDs), and their transesterification activity and enantioselectivity in organic solvents were evaluated. The PCL co-lyophilized with each additive showed simultaneously enhanced enzyme activity and enantioselectivity when compared to the native lipase lyophilized from buffer alone; in contrast, such enhancement was not observed for the co-lyophilized CRL. Among the cyclic oligoethers examined, permethylated betaCyD (Me1.78betaCyD), as the most suitable additive, was used for the optimization of both the co-lyophilized PCL preparation and reaction conditions by determining the effects of varying the additive/lipase ratio, aqueous pH, the nature of organic solvents, and temperature. The initial rate determined for the transesterification between racemic 2,2-dimethyl-1,3-dioxolane-4-methanol and vinyl butyrate in diisopropyl ether at 30 degrees C increased by up to 17-fold and the enantioselectivity represented by E could be doubled. While there was an inverse correlation between temperature and enantioselectivity, with the Me1.78betaCyD-PCL co-lyophilizate, the reaction rate even at 0 degrees C was much higher than that at higher temperatures in the native PCL-catalyzed reaction. Hence, this method seems to be of practical use for the large-scale production of optically active compounds.     

Effects of Processing Parameters on the Deposition of Yttria Partially Stabilized Zirconia Coating During Suspension Plasma Spray

The process–microstructure relationship in suspension plasma spray (SPS) of yttria partially stabilized zirconia (YSZ) has been studied experimentally. An ethanol‐based suspension with a powder loading of 25 wt% was plasma sprayed with radial injection under four different plasma conditions, to examine the effects of plasma gas composition (Ar/He ratio), secondary gas (Ar/He and Ar/H₂), and the nozzle diameter of the plasma gun. The suspension feeding rate was optimized firstly and coatings were prepared for microstructural observation. Capturing of in‐flight particles into water as well as collection of splats formed on heated flat metal substrates were utilized in order to better understand the more complicated intermediate process steps in SPS. It was found that a plasma jet with higher momentum allowed a higher suspension flow rate and both columnar and deep vertically cracked structure could be created depending on the plasma parameters as well as the substrate surface roughness.     

Lipid Composition and Antioxidant Capacity Evaluation in Tilapia Fillets Supplemented with a Blend of Oils and Vitamin E

Since the nutritional value of farm‐raised fish fillets is directly related to the diet provided, we supplemented the diet of Tilapia (Oreochromis niloticus) with a blend of chia (Salvia hispanica L.) oil, tung (Aleurites fordii) oil, and conjugated linoleic acid (CLA) to evaluate the effects on the fatty acid composition. Vitamin E was also added to the diet to improve the antioxidant capacity of tilapia fillets. We observed an increase in α‐linolenic acid content (from 6.56 to 19.03 mg g^?1 of total lipids), as well as the incorporation of CLA and conjugated linolenic acid (CLnA) isomers in the fillets. The addition of vitamin E resulted in the antioxidant capacity improvement of the fillets and higher values were found after 15 feeding days (39.25 µmol TE g^?1 in the Ferric Reducing Ability Power assay). Supplementation proved to be an excellent tool to improve the nutritional value of fish fillets.     

A Helix‐Stabilized Cell‐Penetrating Peptide as an Intracellular Delivery Tool

Two types of cationic cyclic α,α‐disubstituted α‐amino acids: Api (which possesses a lysine mimic side chain) and Api^C2Gu (which possesses an arginine mimic side chain), were developed. These amino acids were incorporated into an arginine‐based peptide sequence [(l ‐Arg‐l ‐Arg‐dAA)₃: dAA=Api or Api^C2Gu], and the relationship between the secondary structures of the resulting peptides and their ability to pass through cell membranes was investigated. The peptide containing Api^C2Gu formed a stable α‐helical structure and was more effective at penetrating cells than the nonhelical Arg nonapeptide (R₉). Furthermore, the peptide was able to deliver plasmid DNA into various types of cells in a highly efficient manner.     

Development of Tetrachlorophthalimides as Liver X Receptor β (LXRβ)‐Selective Agonists

Liver X receptor (LXR) agonists are candidates for the treatment of atherosclerosis via induction of ABCA1 (ATP‐binding cassette A1) gene expression, which contributes to reverse cholesterol transport (RCT) and to cholesterol efflux from the liver and intestine. However, LXR agonists also induce genes involved in lipogenesis, such as SREBP‐1c (sterol regulatory binding element protein 1c) and FAS (fatty acid synthase), thereby causing an undesirable increase in plasma and hepatic triglyceride (TG) levels. Recent studies indicate that LXRα contributes to lipogenesis in liver, and selective LXRβ activation improves RCT in mice. Therefore, LXRβ‐selective agonists are promising candidates to improve atherosclerosis without increasing plasma or hepatic TG levels. However, the ligand‐binding domains in the two LXR isoforms α/β share high sequence identity, and few LXR ligands show subtype selectivity. In this study we identified a tetrachlorophthalimide analogue as an LXRβ‐selective agonist. Structural development led to (E)‐4,5,6,7‐tetrachloro‐2‐(2‐styrylphenyl)isoindoline‐1,3‐dione ( 24 a ), which shows potent and selective LXRβ agonistic activity in reporter gene assays. In binding assays, compound 24 a bound to LXRβ preferentially over LXRα. It also induced the expression of ABCA1 mRNA but not SREBP‐1c mRNA in cells. Compound 24 a appears to be a promising lead compound for therapeutic agents to treat atherosclerosis without the side effects induced by LXRα/β dual agonists.     

Plasmonic enhancements of photoluminescence in hybrid Si nanostructures with Au fabricated by fully top-down lithography

The authors study plasmonic enhancements of photoluminescence (PL) in Si nanodisk (ND) arrays hybridized with nanostructures such as nanoplates of Au, where these hybrid nanostructures are fabricated by fully top-down lithography: neutral-beam etching using bio-nano-templates and high-resolution electron-beam lithography. The separation distance between the Si ND and Au nanostructure surfaces is precisely controlled by inserting a thin SiO₂ layer with a thickness of 3 nm. We observe that PL intensities in the Si NDs are enhanced by factors up to 5 depending on the wavelength by integrating with the Au nanoplates. These enhancements also depend on the size and shape of the Au nanoplates.     

Printed silver nanowire antennas with low signal loss at high-frequency radio

Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film.     

Effect of the licorice flavonoid isoliquiritigenin on the sleep architecture and profile in mice

The sleep-promoting effect of isoliquiritigenin (ILTG) was investigated by analyzing the sleep architecture in mice. A hypnotic diazepam (DZP, 2 mg/kg) significantly decreased sleep latency by 39.7% and increased the amount of non-rapid eye movement sleep (NREMS) by 103.8% for the first 3 h after administration. ILTG (50 mg/kg) also produced a significant decrease in sleep latency (30.7%) and an increase in the amount of NREMS (61.1%). DZP significantly decreased delta (0.5–4 Hz) activity as compared with the vehicle; however, ILTG did not alter the delta activity. These results mean that ILTG induces sleep similar to physiological sleep without a decline in sleep quality.     

Isolation of a novel alkaline-induced laccase from Flammulina velutipes and its application for hair coloring

Laccase is a member of the multi-copper oxidase family and a promising for hair coloring. In this study, we isolated a novel alkaline-induced laccase from the white-rot fungus Flammulina velutipes and studied the possibility to apply the enzyme for hair coloring. Laccase activity detected in the culture supernatant of F. velutipes was found to significantly increase when exchanging the medium to laccase inducing one whose pH was adjusted to 9.0. Three isozymes were detected by activity staining on non-denaturing SDS-PAGE. The major isozyme, Flac1, was purified from the culture supernatant after being induced at pH 9.0 by ion-exchange column chromatography. The N-terminal peptide sequence of Flac1 was determined, revealing clear homology with laccases from other white-rot fungi. Optimum pH of oxidation was found to be around pH 5.0-6.5 regardless of several different substrates used. Oxidation activities of Flac1 to several hair dye agents as substrate showed the higher activity at pH 6.5 than that at pH 9.0. Oxidation activity was also detected at pH 9.0 which was suitable for hair coloring. When the purified Flac1 was applied for hair coloring system without using hydrogen peroxide, effective coloring was observed at the protein amount of 0.25mg/1g of hair used. These results indicated that this alkaline-induced novel laccase isolated from the culture supernatant of F. velutipes might be a useful enzyme for hair color.