Effects of fullerene encapsulation on structure and photophysical properties of porphyrin-linked single-walled carbon nanotubes

Fullerene-encapsulating single-walled carbon nanotubes (C(60)@SWNT) linked with porphyrins by a short bridge have been prepared for the first time. Steady state and time-resolved spectroscopies demonstrated the initial formation of an exciplex state, followed by a charge-separated state.     

Incorporation of organometallic Ru complexes into apo-ferritin cage

Spherical protein cages such as an iron storage protein, ferritin, have great potential as nanometer-scale capsules to assemble and store metal ions and complexes. We report herein the synthesis of a composite of an apo-ferritin cage and Ru(p-cymene) complexes. Ru complexes were efficiently incorporated into the ferritin cavity without degradation of its cage structure. X-Ray crystallography revealed that the Ru complexes were immobilized on the interior surface of the cage mainly by the coordination of histidine residues.     

Photoinduced Reversible Topographical Changes on Diarylethene Microcrystalline Surfaces with Biomimetic Wetting Properties

Reversible topographical changes were observed on a photochromic diarylethene microcrystalline film surface by alternate irradiation with UV and visible light. Two types of surfaces were prepared from this film: 1) Storage of the film at 30 °C for 24 hours in the dark after UV irradiation afforded a surface that was covered with needle‐shaped crystals, whose diameter and length were approximately 1 μm and 10 μm, respectively, and showed a superhydrophobic lotus effect. 2) Storage of the film at 70 °C for 3 hours in the dark caused the needle‐shaped crystals to be converted into larger rod‐like crystals (5∼8 μm wide and 20∼30 μm long) by Ostwald ripening and a disappearance of the lotus effect. The obtained activation energy of the formation of the needle‐ and rod‐shaped crystals was 143 and 162 kJ mol⁻¹, respectively. Subsequent UV irradiation to the surface, which was followed by storage at 50 °C for 1 hour in the dark, gave a doubly rough structure; small needle‐shaped crystals were formed between the larger rod‐shaped crystals. The surface showed both superhydrophobic properties and the pinned effect of the water droplet: the petal effect. Fractal analysis of both surfaces were carried out using a box‐counting method, and the lotus effect was observed in the presence of smaller‐sized crystals, whilst the petal effect was observed with larger sized crystals (ca. 100 μm). We demonstrated that the hydrophobic property was controlled by the distribution in crystal size of the closed‐ring isomer of the diarylethene. Visible‐light irradiation of both rough surfaces afforded surfaces with cubic‐shaped micro‐crystals of the open‐ring isomer.     

Cloning and functional characterization of a fructan 1-exohydrolase (1-FEH) in edible burdock (<Emphasis Type="Italic">Arctium lappa</Emphasis>L.)

Background  

We have previously reported on the variation of total fructooligosaccharides (FOS), total inulooligosaccharides (IOS) and inulin in the roots of burdock stored at different temperatures. During storage at 0°C, an increase of FOS as a result of the hydrolysis of inulin was observed. Moreover, we suggested that an increase of IOS would likely be due to the synthesis of the IOS by fructosyltransfer from 1-kestose to accumulated fructose and elongated fructose oligomers which can act as acceptors for fructan:fructan 1-fructosyltransferase (1-FFT). However, enzymes such as inulinase or fructan 1-exohydorolase (1-FEH) involved in inulin degradation in burdock roots are still not known. Here, we report the isolation and functional analysis of a gene encoding burdock 1-FEH.     

A rapid gel electrophoretic chip for serum cholesterol determination

We present a rapid gel electrophoretic chip, composed of 2.5% (w/v) acrylamide and 1% (w/v) agarose gel, for serum cholesterol determination using a photo lithography technique. After optimizations, we determined the lipoprotein concentration of standard serum using a conventional enzyme method. The serum was diluted, stained and loaded for 15 min onto the chip. After loading, the intensities of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) bands separated at the chip were estimated using an image analyzer. The intensities of these bands corresponded to concentrations obtained from a standard enzyme-based method. The detected LDL-C and HDL-C concentrations were linear up to 146 mg dL(-1) and 53 mg dL(-1) respectively. Finally, we carried out the cholesterol analysis using real biological samples obtained from nine volunteers using our electrophoretic chip. The LDL-C and HDL-C levels detected using our chip correlated well with the results obtained using the conventional enzyme-based method r(2) = 0.98 and r(2) = 0.86 for LDL-C and HDL-C, respectively. Although our sample size is small and confined only to health volunteers, we have demonstrated that this proof-of-concept gel electrophoretic chip can determine lipoproteins, simultaneously.     

Do amorphous troglitazones prepared from two diastereomer-pairs have the same molecular mobility and crystallization rate at the surface?

The surface of amorphous compounds crystallizes faster compared to the bulk. This suggests that molecules at the surface have high molecular mobility. Crystallization behavior is affected by various factors including molecular weight and glass transition temperature (T(g)). In this study, we focus on troglitazone which is composed of diastereomers, RR/SS and RS/SR, as model compound, because each diastereomer has the same molecular weight and similar chemical structure. Troglitazone is isolated into each diastereomer, and both amorphous prepared from RR/SS and RS/SR showed similar T(g) (around 60°C). The surface relaxation of each amorphous troglitazone prepared from two diastereomers, RR/SS and RS/SR, was determined to compare surface molecular mobility, using inverse gas chromatography under dry conditions. As a result, amorphous prepared from RS/SR, showed the shorter surface relaxation time at 40°C (temperature below T(g)), which means it has higher molecular mobility than that from RR/SS at the surface although both have the same molecular weight and similar T(g). Microscopy analysis was conducted to observe the crstallization behavior at the surface of amorphous troglitazone in conditions of high temperature and humidity. Micrographs showed that crystallization area at the surface of amorphous prepared from RS/SR, which showed the shorter surface relaxation time, increased faster than that of the amorphous prepared from RR/SS. Although the reason for the difference in the surface relaxation time of each amorphous troglitazone could not be determined, factors such as the difference of configuration might affect the difference.