Stable G-quadruplex structure in a hydrated ion pair: cholinium cation and dihydrogen phosphate anion

A combination of cholinium cations and dihydrogen phosphate anions is indispensable for the G-quadruplex structure regardless of water content. No G-quadruplex structure was observed in most salts even containing either cholinium cations or dihydrogen phosphate anions.     

Biogenous iron oxide-immobilized palladium catalyst for the solvent-free Suzuki–Miyaura coupling reaction

Iron oxide produced by iron-oxidizing bacteria, Leptothrix ochracea, (biogenous iron oxide: BIO) was used as a support for immobilized palladium catalysts with organic cross-linkers. Palladium immobilized on BIO bearing imidazolium chloride delivered the desired biaryl products in sufficient yields in the Suzuki–Miyaura coupling reactions under solvent-free conditions and could be reused several times without significant loss of catalytic activity. It is shown that BIO can be exploited as a useful support for immobilization of palladium and the BIO-immobilized palladium catalyst effectively promotes the solvent-free Suzuki–Miyaura coupling reactions.     

Carbon nanotube enhanced mediator-type biosensor for real-time monitoring of glucose concentrations in fish

We have developed a mediator-type biosensor to rapidly monitor blood glucose concentrations in fish, which are an indicator of stress. Glucose oxidase was used to detect glucose concentrations and ferrocene was used to limit the effect of oxygen. We also improved the sensitivity and durability of the sensor for better performance. Single-walled carbon nanotubes were used to enhance sensor sensitivity. Affixing the carbon nanotubes (30 mg ml^-1) to the working electrode increased the sensor sensitivity to 61.9 mM nA^-1 mm^-2, twice the value for the sensor without single-walled carbon nanotubes. A fabricated mediator-type biosensor sensor was used to perform real-time in vivo measurements. The sensor was implanted into the interstitial fluid of a fish eyeball, and detection was transmitted to a personal computer by a wireless potentiostat. Continuous measurement of the glucose concentration was possible for 78 hours. Stress was artificially applied to the fish during the measurement, and the change of blood glucose concentrations were observed. Our proposed sensor is applicable for effectively monitoring stress in free-swimming fish.     

Plasmonic resonance enhancement of single gold nanorod in two-photon photopolymerization for fabrication of polymer/metal nanocomposites

We investigated the plasmonic resonance enhanced two-photon photopolymerization (PETPP) using the isolated chemical synthesized gold nanorods for fabrication of polymer/metal nanocomposites. The isolated gold nanorods with the plasmonic resonance band around 750 nm covered by photoresist were irradiated by a femtosecond laser with the wavelength of 780 nm. The PETPP trigged by the plasmonic resonance enhancement of gold nanorods was localized only in the distance smaller than 30 nm from the surface of gold nanorods, which matched the distance of plasmonic resonant enhanced field of the gold nanorod. The shapes of obtained polymer/gold nanocomposites were changed from the “dumbbell” to the “ellipsoid” with the increase of laser irradiating intensity used for PETPP. This study would provide a potential method for fabricating the plasmonic nanomaterials and nanostructures of polymer/metal nanocomposites, which could be expected to be applied in the emerging fields such as nanophotonics, nanobiosensor, nanolithography.     

Synthesis of phosphorylcholine-oligoethylene glycol-alkane thiols and their suppressive effect on non-specific adsorption of proteins

A series of phosphorylcholine-oligoethylene glycol-alkane thiols were synthesized, and their suppressive effect on the non-specific adsorption of proteins was evaluated by comparison with corresponding oligoethylene glycol-alkane thiols. It was found that phosphorylcholine-oligoethylene glycol-alkane thiols had a greater suppressive effect on the non-specific adsorption of proteins.     

Wireless biosensor system for real-time cholesterol monitoring in fish “Nile tilapia”

The rapidly increasing demand for cultured fish as a food resource requires simple, effective methods for controlling fish health in culture conditions. Plasma total cholesterol levels are significantly related to fish mortality following bacterial challenge, and are thus a good indicator of the general health of fish. We developed a wireless biosensor system to continuously monitor the total cholesterol concentration in fish (Nile tilapia, Oreochromis niloticus). The biosensor was constructed with Pt-Ir wire (φ0.178 mm) as the working electrode and Ag/AgCl paste as the reference electrode. Cholesterol oxidase and cholesterol esterase were immobilized on the working electrode using glutaraldehyde. The sensor output was linear and strongly correlated with the cholesterol level (R = 0.9970) in the range of 2.65-403 mg dl⁻¹. This range covers the range of total cholesterol levels in fish. To avoid blood coagulation and proteins coalescing on the sensor, we implanted the sensor in the fluid under the scleral surface of the eyeball (EISF). The EISF is presumed to reflect the levels of most blood components and does not include the substances contained in blood that inhibit sensor measurement. Total cholesterol concentrations in blood and EISF were strongly correlated (R = 0.8818, n = 72) in the blood total cholesterol range of 74-480 mg dl⁻¹. Therefore, we used EISF as an alternative to blood and performed continuous in vivo-monitoring of the total cholesterol concentration in fish. We also investigated the application of the calibration method and wireless monitoring system. These applications enabled us to securely monitor total cholesterol levels in free-swimming fish in an aquarium for over 40 h. Thus, our newly developed sensor provided a rapid and convenient method for real-time monitoring of total cholesterol concentrations in free-swimming fish.     

Stepwise Reduction of Azapentabenzocorannulene

Mono‐ and dianions of 2‐tert‐butyl‐3a²‐azapentabenzo[bc,ef,hi,kl,no]corannulene ( 1 a ) were synthesized by chemical reduction with sodium and cesium metals, and crystallized as the corresponding salts in the presence of 18‐crown‐6 ether. X‐ray diffraction analysis of the sodium salt, [{Na⁺(18‐crown‐6)(THF)₂}₃{Na⁺(18‐crown‐6)(THF)}( 1 a ^2?)₂], revealed the presence of a naked dianion. In contrast, controlled reaction of 1 a with Cs allowed the isolation of singly and doubly reduced forms of 1 a , both forming π‐complexes with cesium ions in the solid state. In [{Cs⁺(18‐crown‐6)}( 1 a ^?)]?THF, asymmetric binding of the Cs⁺ ion to the concave surface of 1 a ^? is observed, whereas in [{Cs⁺(18‐crown‐6)}₂( 1 a ^2?)], two Cs⁺ ions bind to both the concave and convex surfaces of the dianion. The present study provides the first successful isolation and characterization of the reduced products of heteroatom‐containing buckybowl molecules.     

The Progress of the Gait Impairment and Brain Activation in a Patient with Post-stroke Hemidystonia

Objective: We explore the effects of body weight-supported (BWS) treadmill training, including the change of cortical activation, on a patient with post-stroke hemidystonia. Patient: The patient was a 71-year-old man with left thalamus hemorrhage. His motor symptoms indicated slight impairment. There was no overactive muscle contraction in the supine, sitting, or standing positions. During his gait, the right initial contact was the forefoot, and his right knee showed an extension thrust pattern. These symptoms suggested that he had post-stroke hemidystonia. Methods: The patient performed BWS treadmill training 14 times over 3 weeks. The effects of the BWS training were assessed by a step-length analysis, electromyography and functional magnetic resonance imaging (fMRI). Results: The patient''s nonparetic step length was extended significantly in the Inter-BWS (p<0.001) and Post-BWS (p=0.025) periods compared to the Pre-BWS session. The excessive muscle activity of the right gastrocnemius medialis in the swing phase was decreased at the Inter-BWS, Post-BWS, and follow-up compared to the Pre-BWS session. The peak timing difference of the bilateral tibialis anterior muscle became significant (p<0.05) on the first day of the intervention. The fMRI revealed that the cortical areas activated by the motor task converged through the intervention (p<0.05, family-wise error corrected). Conclusion: These results suggest that there was improvement of the patient''s symptoms of post-stroke hemidystonia due to changes in the brain activity during voluntary movement after BWS intervention. Body weight-supported treadmill training may thus be an effective treatment for patients with poststroke hemidystonia.     

High-performance liquid chromatographic separation of carbohydrates on graphitized carbon columns

Graphitized carbon columns (GCC) for high-performance liquid chromatography are relatively new and have a unique ability to resolve isomeric and closely related compounds. The retention mechanism of carbohydrates on GCC is mainly based on adsorption and the flat surface of GCC packing brings about unique selectivity, but also includes hydrophobic interactions. The chromatographic behaviour of monosaccharides, disaccharides, cyclodextrins (CDs), branched CDs, oligosaccharide alditols, chito-oligosaccharides, N-linked oligosaccharides and glycopeptides has been studied, and it has become apparent that the elution patterns are based on the size and planarity of the molecule (position and configuration of linkage).