Building a novel vitronectin assay by immobilization of integrin on calixarene monolayer

Membrane proteins possess significant hydrophobic domains and are likely to deplete their native activity immobilized on the solid surface relative to those occurring in a membrane environment. To investigate an efficient immobilization method, calix[4]crown-ether monolayer as an artificial protein linker system was constructed on the gold surface and characterized by Fourier transform infrared reflection absorption spectroscopy (FTIR-RAS), atomic force microscopy (AFM) and cyclic voltammetry (CV). Integrin alpha(v)beta3 was functionally immobilized onto the monolayer and the integrin-vitronectin interaction was investigated by surface plasmon resonance (SPR). It was found that calix[4]crown-ether was assembled as a monolayer on the gold surface. Orientation and accessibility of integrin alpha(v)beta3 was assessed by sensitive binding of its natural ligand, vitronectin at pg mL(-1) level. Moreover, surface coverage of integrin layer and thickness calculated through SPR curve simulation verified that integrin layer was a monolayer in activated form. In combination with the SPR method, this calix[4]crown monolayer provided a reliable and simple experimental platform for the investigation of isolated membrane proteins under experimental conditions resembling those of their native properties.     

Field‐Effect Nanoparticle‐Based Glucose Sensor on a Chip: Amplification Effect of Coimmobilized Redox Species

A capacitive EIS (electrolyte‐insulator‐semiconductor) structure was modified with gold nanoparticles together with glucose oxidase and used as field‐effect‐based glucose biosensor using the constant capacitance mode. Co‐immobilization of ferrocene redox species resulted in a two‐fold increase of the biosensor sensitivity. The effect was explained by the hydrogen peroxide‐mediated oxidation of ferrocene resulting in a pool of charged species at the interface increasing the sensor response towards glucose. The studied approach was suggested as a general means to amplify signals from Si chip‐based field‐effect enzyme biosensors.     

A new semi-analytical method for the non-linear static analysis of an infinite beam on a non-linear elastic foundation: A general approach to a variable beam cross-section

We propose a new non-linear method for the static analysis of an infinite non-uniform beam resting on a non-linear elastic foundation under localized external loads. To this end, an integral operator equation is newly formulated, which is equivalent to the original differential equation of non-uniform beam. By using the integral operator equation, we propose a new functional iterative method for static beam analysis as a general approach to a variable beam cross-section. The method proposed is fairly simple as well as straightforward to apply. An illustrative example is presented to examine the validity of the proposed method. It shows that just a few iterations are required for an accurate solution.     

The effect of photoactivated transformations of Ag+ and Ag0 in silica fillers on their biocidal activity

Research on Chemical Intermediates - Ag and AgCu containing powdered silica fillers of polymers for medical applications have been synthesized using mechanochemical activation with a low content of...     

Water-Soluble Conjugates of ZnS:Mn Quantum Dots with Chlorin e6 for Photodynamic Therapy

An algorithm for wavefront calculation of ordinary and extraordinary waves after propagation through hemispherical components made of a uniaxial crystal is developed. The influence of frequency dispersion of n _о and n _e , as well as change in the direction of the optic axis of the crystal, on extraordinary wavefront in hemispheres made of from leuco-sapphire and a plastically deformed analog thereof is determined.     

Photocatalytic Properties of Hybrid Nanostructures Based on Nanoparticles of TiO<Subscript>2</Subscript> and Semiconductor Quantum Dots

Multilayer hybrid nanostructures based on nanoparticles of TiO₂ and CdSe/ZnS semiconductor quantum dots were formed. Generation of active forms of oxygen by hybrid nanostructures under visible-light irradiation is demonstrated to take place, which is indicative of efficient photoinduced electron transfer from quantum dots to titanium-oxide nanoparticles contained in the hybrid nanostructures.     

Di‐μ‐methoxo‐bis({N,N′‐bis­[2‐(3,5‐di­methyl­pyrazol‐1‐yl)­ethyl]­amine‐κ3N}copper(II)) bis­(hexa­fluoro­phosphate)

The title compound, [Cu₂(C₁₄H₂₃N₅)₂(CH₃O)₂](PF₆)₂, has a doubly methoxo‐bridged centrosymmetric copper dimer cation involving two tridentate bis­(pyrazolyl)­amine ligands. The geometry of each Cu^II atom is a distorted square pyramid with two N atoms of the pyrazole in bis­[2‐(3,5‐di­methyl‐1‐pyrazolyl)­ethyl]­amine (bpea) and two μ₂‐bridging O atoms of the methoxo ligands forming the basal plane, and the amine N atom occupying the axial position. In the bridging plane, the Cu—O bond lengths are 1.940 (4) and 1.942 (4) Å, and the bond angles for O—Cu—O and Cu—O—Cu are 76.1 (2) and 103.9 (2)°, respectively. The Cu?Cu distance is 3.058 (1) Å. The central four‐membered ring lies on an inversion centre.     

Curing reaction of biphenyl epoxy resin with different phenolic functional hardeners

The investigation of cure kinetics and relationships between glass transition temperature and conversion of biphenyl epoxy resin (4,4′-diglycidyloxy-3,3′,5,5′-tetramethyl biphenyl) with different phenolic hardeners was performed by differential scanning calorimeter using an isothermal approach over the temperature range 120–150°C. All kinetic parameters of the curing reaction including the reaction order, activation energy, and rate constant were calculated and reported. The results indicate that the curing reaction of formulations using xylok and dicyclopentadiene type phenolic resins (DCPDP) as hardeners proceeds through a first-order kinetic mechanism, whereas the curing reaction of formulations using phenol novolac as a hardener goes through an autocatalytic kinetic mechanism. The differences of curing reaction with the change of hardener in biphenyl epoxy resin systems were explained with the relationships between T_g and reaction conversion using the DiBenedetto equation. A detailed cure mechanism in biphenyl-type epoxy resin with the different hardeners has been suggested. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 773–783, 1998     

A new approach for estimating the recrystallization rate and equilibrium melting temperature

A method is described for measuring the heat and rate of recrystallization following partial melting. The method uses a specific sequence of temperatures with a differential scanning calorimeter, and the melting and recrystallization processes were confirmed by optical observations. The method was applied to poly(butylene terephthalate). The rate of recrystallization was found to be roughly two orders of magnitude faster than isothermal crystallization from the melt. The melting temperatures obtained from recrystallization were used in the Hoffman–Weeks equation to deduce 236°C as the equilibrium melting temperature for poly(butylene terephthalate). © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 133–141, 1998