Development of a solid-supported biotinylation reagent for efficient biotin labeling of SH groups on small molecules

We report here the design and synthesis of a novel and selective SH-group biotinylating reagent, KSH-1 (1), for the biotinylation of small molecules using solid phase chemistry. The results demonstrate that 1 efficiently biotinylated a small molecule, captopril, and afforded the product in high yield and purity.     

Super-liquid-repellent surfaces prepared by colloidal silica nanoparticles covered with fluoroalkyl groups

A simple and easy method to prepare super-liquid-repellent surfaces is proposed. Sol-gel films were prepared by hydrolysis and condensation of alkoxysilane compounds. Both surface energy and roughness were controlled using colloidal silica particles and fluoroalkylsilane. When the fractional amounts of both colloidal silica and fluoroalkylsilane were optimized in the films, the film surface exhibited repellency to both water and oil. Finally, it was shown that the method proposed here would be applied to a simple one-pot coating for a uniform large area, and be useful for practical use.     

Thermal switching characteristics based on smectic-A↔chiral nematic phase transitions of (liquid crystals/chiral dopant) composites,with and without side chain-type liquid crystalline polymer

The light switching characteristics induced by a thermal smectic A (SmA) ? chiral nematic (N*) phase transition were studied for homeotropically aligned [smectic A liquid crystal (SmA-LC)/nematic liquid crystal (N-LC)/chiral dopant] and [side chain type smectic A liquid crystalline polymer (SmA-LCP)/N-LC/chiral dopant] composites. A drastic change from a transparent SmA phase to a light-scattering N* phase occurred in both composites upon heating. In the case of the heat-induced N* phase for the (SmA-LC/N-LC/chiral dopant) composite, the N* phase exhibited weak light scattering due to formation of a scroll texture. On the other hand, in the case of the heat-induced N* phase for the (SmA-LCP/N-LC/chiral dopant) composite, the N* phase showed strong light scattering due to formation of a focalconic texture. The existence of a SmA-LCP was responsible for a higher contrast ratio between the transparent SmA phase and the light scattering N* phase for the (SmA-LCP/ N-LC/chiral dopant) composite than for the (SA-LCN/N-LC/chiral dopant) composite.     

Thermal characteristics of ammonium nitrate, carbon, and copper(II) oxide mixtures

Ammonium nitrate (AN) has been extensively used as an oxidizer in energetic compositions, and is a promising compound as a propellant and gas generator. It is well-known that metal oxides help to address some of the disadvantages of AN, such as low stability and a low burning rate in these applications. In order to investigate the effects of copper(II) oxide (CuO) on the thermal decompostion of AN mixtures, the thermal characteristics of AN, carbon, and CuO mixtures were measured using simultaneous differential scanning calorimetry and thermogravimetry–differential thermal analysis connected with infrared spectroscopy and mass spectrometry. As a combustible material, activated carbon (AC), and carbon black (CB) were used in this study. In the TG–DTA results for AN/AC/CuO and AN/CB/CuO mixtures in an open cell, an exotherm was observed at approximately 210 and 230 °C, respectively. In addition, the IR and mass spectra of the gases produced from the AN/AC/CuO and AN/CB/CuO mixtures indicated the presence of CO₂. Notably, the effect of CuO addition on the oxidation of the AN/AC/CuO mixture was different from that on the AN/CB/CuO mixture; the oxidation of AC shifted to a lower temperature, while the oxidation of CB shifted to a higher temperature. These results suggest that the effect of CuO on the oxidation of different types of carbon depends on the chemical reactivity of the carbon, which is derived from its physical properties.     

Morphological studies of a (self-assembling oil gelator/liquid crystal) composite system

The aggregation structure of a novel (self-assembling oil gelator/liquid crystal) composite was investigated using light scattering studies and morphological observations. The oil gelator forms a self-assembled-networks aggregate in an organic solvent with a low molecular weight liquid crystal (LC). It became apparent from Hv light scattering patterns and polarizing optical microscopy that two types of LC molecular alignments exist in the composite: a random orientation and a spherulite type one in a nematic gel state. Also, optical and atomic force microscopic observations revealed that fibrils which formed bundles in the fibre-like and spherulite-like aggregates, were formed in the composite. The alignment of the liquid crystal molecules was related to the aggregation structure of the self-assembling oil gelator in a liquid crystal gel state.     

Formulation design of taste-masked particles, including famotidine, for an oral fast-disintegrating dosage form

In this study, the taste-masking of famotidine, which could apply to any fast-disintegrating tablet, was investigated using the spray-dry method. The target characteristics of taste-masked particles were set as follows: the dissolution rate is not to be more than 30% at 1 min and not less than 85% at 15 min, and the particle size is not to be more than 150 microm in diameter to avoid a gritty feeling in the mouth. The target dissolution profiles of spray-dried particles consisting of Aquacoat ECD30 and Eudragit NE30D or triacetin was accomplished by the screening of formulas and the appropriate lab-scale manufacturing conditions. Lab-scale testing produced taste-masked particles that met the formulation targets. On the pilot scale, spray-dried particles with attributes, such as dissolution rate and particle size, of the same quality were produced, and reproducibility was also confirmed. This confirmed that the spray-dry method produced the most appropriate taste-masked particles for fast-disintegrating dosage forms.     

The relationship between the electrospray ionization behaviour and biological activity of some phosphino Cu(I) complexes

Electrospray ionization mass spectrometry was usefully employed for the characterization of three phosphino copper(I) complexes of medicinal interest. This technique revealed that the original [CuL₄]⁺ pro‐drugs (L = hydrophilic tertiary phosphine) underwent dissociation with production of coordinative unsaturated [CuL₃]⁺ and [CuL₂]⁺ species, which represented key intermediates for the activation of potential biological properties. The more favoured was the displacement of the ligands from the [CuL₄]⁺ parent complex, the more favoured was in turn the possibility for the metal ion to directly interact with biological substrates, including pharmacological targets related to cancer proliferation. An inverse correlation between the stability and the cytotoxic activity of the three copper(I) complexes investigated has been clearly established. Copyright © 2010 John Wiley & Sons, Ltd.