Preparation of prolonged-release spherical micro-matrix of ibuprofen with acrylic polymer by the emulsion-solvent diffusion method for improving bioavailability

Prolonged-release spherical micro-matrices of ibuprofen with acrylic polymer (Eudragit RS) were prepared using a novel emulsion-solvent diffusion method. It was found by examining cross sections of the spherical matrix before and after dissolution tests with a scanning electron microscope and a porosimeter that the resultant micro-matrix had a sponge-like internal structure. The spherical matrices were successfully recovered with a relatively high concentration of the drug in ethanol (0.4-0.6 g/ml) and over a wide range of temperatures (5-35 degrees C). The size of the spherical matrix could be easily controlled by varying the agitation speed of the system and the concentration of emulsifier added to the aqueous medium. The drug release rate from the spherical matrix decreased with increasing concentration of polymer formulated due to the reduced diffusion path and increased tortuosity in the matrix. Spherical matrices with ibuprofen:Eudragit RS = 3:1 improved the bioavailability of the drug and prolonged the drug action in beagle dogs.     

A plug and play microfluidic device

Chip-to-world interface is a major issue in the field of microfluidics and its applications. We developed a plug and play microfluidic device composed of a fluid driving unit and a polymer chip containing microfluidic channels and reservoirs. The one and only connection of the device to the external world is a set of electric control lines for the driving unit. Just putting the reagents and samples onto the reservoirs, the chip can be operated for chemical or biochemical reaction and analysis. We demonstrate here that silicon-based micropumps embedded in the present device allow us to achieve flexible fluidic manipulations with minimum time delay and dead volume.     

Highly sensitive spectrophotometric determination of osmium(VIII) with pyrogallolphthalein and hydrogen peroxide in the presence of Brij 35

Summary A highly sensitive determination of osmium(VIII) is based on the decolouring reaction with pyrogallolphthalein (gallein) and hydrogen peroxide in the presence of Brij 35. Beer's law was obeyed in the range of 0–0.5 ng of osmium(VIII) per 10 ml and the apparent decomposed absorption coefficient was 2.5×10⁹ l mol^–1 cm^–1 at 535 nm.Application of xanthene derivatives in analytical chemistry. Part XCIII. Part XCII see ref. [1]     

Rate constants of the O(D) reactions with N2, O2, N2O, and H2O at 295 K

Using a technique of laser flash photolysis coupled with vacuum ultraviolet laser-induced fluorescence spectroscopy, the rate coefficients of O(¹D) reactions with N₂, O₂, N₂O, and H₂O at 295 ± 2 K have been determined to be , k_O2=(4.06±0.24)×10^-11, k_N2O=(1.35±0.08)×10^-10 and . The quoted uncertainties include estimated errors and are the 95% confidence level. The k_N2 and k_N2O values obtained are larger than the current NASA/JPL recommendations by 26% and 16%, respectively, although they are still within the error limits associated with the recommendations.     

Basic peptides as functional components of non-viral gene transfer vehicles

Improving the performance of non-viral gene-delivery vehicles that consist of synthetic compounds and nucleic acids is a key to successful gene therapy. Supplementing synthetic vehicles with various biological functions by using natural or artificial peptides is a promising approach with which to achieve this goal. One of the obstacles hindering this effort is that some of the potentially useful peptides, especially those with many basic amino acid residues, interfere with the formation of the complex owing to strong electrostatic interactions with the nucleic acid. In this review, we describe our recent work in examining the potential of these peptides in gene delivery, using a recombinant lambda phage particle as the model for the gene-delivery complex. Lambda phage encapsulates large duplex DNA in a rigid polyplex-like shell with a diameter of 55 nm, and can display various peptides on this capsid, independently of particle formation. By examining the expression of marker genes encapsulated in the phage capsid, we have demonstrated that the protein transduction domain of HIV Tat protein and the nuclear localization signal derived from SV40 T antigen can remarkably facilitate the delivery of these marker genes across the two major barriers, the cell membrane and the nuclear membrane, respectively. Our results indicate that these basic peptides can constitute effective components of synthetic gene-transfer complexes, as long as sufficient copies are displayed on the outer surface of the complex.     

Red–Green–Blue Trichromophoric Nanoparticles with Dual Fluorescence Resonance Energy Transfer: Highly Sensitive Fluorogenic Response Toward Polyanions

A red–green–blue (RGB) trichromophoric fluorescent organic nanoparticle exhibiting multi‐colour emission was constructed; the blue‐emitting cationic oligofluorene nanoparticle acted as an energy‐donor scaffold to undergo fluorescence resonance energy transfer (FRET) to a red‐emitting dye embedded in the nanoparticle (interior FRET) and to a green‐emitting dye adsorbed on the surface through electrostatic interactions (exterior FRET). Each FRET event occurs independently and is free from sequential FRET, thus the resultant dual‐FRET system exhibits multi‐colour emission, including white, in aqueous solution and film state. A characteristic white‐emissive nanoparticle showed visible responses upon perturbation of the exterior FRET efficiency by acceptor displacement, leading to highly sensitive responses toward polyanions in a ratiometric manner. Specifically, our system exhibits high sensitivity toward heparin with an extremely low detection limit.     

Synthesis and some Physical Properties of 1-Cyclohexyl-2-(4”-Halobiphenyl-4'-yl)Ethanes

A series of 1-(trans-4'-n-alkylcyclohexyl)-2-(4”-halobiphenyl-4'-yl)ethanes, which show nematic phases, was prepared. Their transition temperatures, enthalpies and entropies were measured. Their bulk viscosities, birefringences and dielectric constants were determined by extrapolation. 1-(trans-4'-n-propylcyclohexyl)-2-(4”-fluorobiphenyl-4'-yl)ethane has a high clearing of 125° C, a low viscosity of 25 c.p. at 20 °C, a relatively high birefringence of 0.166 at 25 °C, and a positive dielectric anisotropy of 4.9. The transition temperatures, the N-I transition entropies, the bulk viscosities and the birefringences for the 1-(trans-4'-n-alkylcyclohexyl)-2-(4”-fluorobiphenyl-4'-yl)ethanes exhibited odd-even effects in relation to the number of carbon atoms in the alkyl chain. The bulk viscosity as a function of the third power of the van der Waals radius of the halogeno group, the birefringence as a function of the van der Waals radius of the halogeno group, and the dielectric constants as a function of the dipole moment of the halogeno group are discussed for the 1-(trans-4'-n-propylcyclohexyl)-2-(4”-halobiphenyl-4'-yl)ethanes.