Preparation and properties of abzyme with thyroxine deiodinase

The abzyme (Se-6E8) with a higher thyroxine deiodinase activity was prepared by modifying the serine residues of monoclonal antibody (6E8)with phenylmethanesulfonyl fluoride and sodium hydrogen selenide, and the 6E8 against O-methyl-T-4, which is a kind of thyroxine derivatives and was taken as a hapten for the first time. Two bands were found corresponding to the 5.5 kD heavy chain and the 2.7 kD light chain respectively by SDS-PAGE. The characteristics of dissociation constants, pH, and temperature were also studied. The results show that the activity of Se-6E8 is 2 010 U/mumol protein, and the proper temperature and pH of the catalytic reactions is 57 degreesC and 8.2 respectively.

Preparation and characterization of a novel beta-cyclodextrin modified poly(N-acetylaniline) film

Hydroquinone was chosen as an electroactive probe to study the beta-cyclodextrin (beta-CD) modified poly(N-acetylaniline) (PNAANI) electrode. The beta-CD modified PNAANI electrode was prepared by electrooxidation of the PNAANI electrode in a beta-CD/DMSO solution. The electrochemical properties of the beta-CD inclusion complex of hydroquinone on the PNAANI electrode and hydroquinone on the beta-CD modified PNAANI electrode were studied. In the cyclic voltammogram of hydroquinone at the beta-CD/PNAANI electrode, DeltaE(p) of the peaks is sharpening and the area of the peaks is increasing, which can be due to the inclusion of hydroquinone into the cavity of beta-CD immobilized at the electrode surface. The beta-CD/PNAANI film was characterized by X-ray photoelectron spectroscopy and H-1 NMR. The mechanism for beta-CD incorporation into the polymer film was also proposed.

Preparation and characterization of ordered yttrium arachidate multilayer

The behavior of arachidic acid on the surface of YCI3 aqueous subphase was studied by LB and Brewster angle microscopy techniques. The results showed that the pre-compressing time and the pH of the subphase played an important role in the forming of the monolayer. The monolayer on the subphase surface was irreversible. If the monolayer was compressed into wrinkles, the monolayer could not become uniform again. The optimum transferring conditions were selected and the ordered yttrium arachidate multilayer with a long spacing of 4.96 nm and a tilt angle of 28.5degrees of the three alkyl chains from the surface normal was fabricated and characterized.

Preparation and properties of conductive polyaniline/poly-omega-aminoundecanoyle fibers

Historically, polyaniline (PANI) had been considered an intractable material, but it can be dissolved in some solvents. Therefore, it could be processed into films or fibers. A process of preparing a blend of conductive fibers of PANI/poly-omega-aminoun-decanoyle (PA11) is described in this paper. PANI in the emeraldine base was blended with PA11 in concentrated sulfuric acid (c-H,SO,) to form a spinning dope solution. This solution was used to spin conductive PANI/PA11 fibers by wet-spinning technology. As-spun fibers were obtained by spinning the dopes into coagulation bath water or diluted acid and drawn fibers were obtained by drawing the as-spun fibers in warm drawing bath water. A scanning electron microscope was employed to study the effect of the acid concentration in the coagulation bath on the microstructure of as-spun fibers. The results showed that the coagulating rate of as-spun fibers was reduced and the size of pore shrank with an increase in the acid concentration in the coagulation bath. The weight fraction of PANI in the dope solution also had an influence on the microstructure of as-spun fibers. The microstructure of as-spun fibers had an influence on the drawing process and on the mechanical properties of the drawn fibers. Meanwhile, the electrically conductive property of the drawn fibers with different percentage of PANI was measured.

Preparation and characterization of poly(ethyl acrylate)/bentonite nanocomposites by in situ emulsion polymerization

Transparent poly(ethyl acrylate) (PEA)/bentonite nanocomposites containing intercalated-exfoliated combinatory structures of clay were synthesized by in situ emulsion polymerizations in aqueous dispersions containing bentonite. The samples for characterization were prepared through direct-forming films of the resulting emulsions without coagulation and separation. An examination with X-ray diffraction and transmission electron microscopy showed that intercalated and exfoliated structures of clay coexisted in the PEA/bentonite nanocomposites. The measurements of mechanical properties showed that PEA properties were greatly improved, with the tensile strength and modulus increasing from 0.65 and 0.24 to 11.16 and 88.41 MPa, respectively. Dynamic mechanical analysis revealed a very marked improvement of the storage modulus above the glass-transition temperature. In addition, because of the uniform dispersion of silicate layers in the PEA matrix, the barrier properties of the materials were dramatically improved. The permeability coefficient of water vapor decreased from 30.8 x 10(-6) to 8.3 x 10(-6) g cm/cm(2)s cmHg. (C) 2002 Wiley Periodicals, Inc.

Preparation and characterization of novel luminescent sol-gel films containing a RE3+ carboxylic acid complex

RE3+ (Eu3+, Tb3+) complexes with carboxylic acid (salicylic acid and benzoic acid) were introduced into the sol, which was prepared by the hydrolysis of tetraethoxysilane (TEOS). A sol-gel luminescent thin film (SG-LTF) was then prepared by dispersing the sol onto a silica substrate by a spin coating method. Multi-layer luminescent thin films were prepared by repeating the same process. The luminescent spectra, fluorescence lifetime and thermal stability of the SG-LTFs were investigated. For the reason of comparison polyvinylbutyral (PVB) was added into a N,N-dimethylformamide (DMF) solution in which the comparative RE3+ carboxylic acid complexes were previously dissolved to form the DMF/PVB solution and the PVB luminescent thin film (PVB-LTF) was prepared. The results show that a broad excitation band indicates the formation of RE complexes in the solid SG-LTFs. RE ions, which are restrained in the silica matrix, present longer lifetimes and higher thermal stability than that in the PVB-LTF containing the corresponding pure complexes. The different doping concentration of RE (III) complexes in the SG-LTFs and the different change of the emission intensities with the heat treatment temperature in the sol-gel thin film and the sol-gel bulk gel were also discussed in this paper.

An organic-inorganic hybrid ultrathin film: preparation and characterization of copper phthalocyanine derivative-ferric oxide nanoparticles

A nanoparticulate ferric oxide-copper tris(2,4-di-tert-amylphenoxy)-8-quinolinolylphthalocyanine hybrid ultrathin film was constructed from alternate layers by the Langmuir-Blodgett technique. The composition, morphology and structure of the film were studied by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, atomic force microscopy, small-angle X-ray diffraction, visible spectroscopy and polarized UV-Vis spectroscopy. All the above analyses suggest that the thin film is a kind of one-dimensional superlattice, composed of organic and inorganic components. The XPS data reveal that the nanoparticulate ferric oxide exists as an alpha-Fe2O3 phase in the films. Gas-sensing measurements show that the hybrid LB film has very fast response-recovery characteristics towards 2 ppm C2H5OH vapor.

Preparation and characterization of PSt-b-PHEMA metal hybrids

The block copolymer polystyrene-b-poly[2-(trimethylsilyloxy)ethylene methacrylate] (PSt-b-PTMSEMA) was synthesized using atom-transfer radical polymerization (ATRP). The hydrolysis of PSt-b-PTMSEMA led to the formation of an amphiphilic block copolymer, polystyrene-b-poly(2-hydroxylethyl methacrylate) (PSt-b-PHEMA), which was characterized by GPC and H-1-NMR. TEM showed that the PSt-b-PHEMA formed a micelle, which is PSt as the core and PHEMA as the shell. Under appropriate conditions, the nickel or cobalt ion cause chemical reactions in these micelles and could be reduced easily. ESCA analysis showed that before reduction the metal existed as a hydroxide; after reduction, the metal existed as an oxide, and the metal content of these materials on the surface is more than that on the surface of the copolymer metal ion. XRD analysis showed that the metal existed as a hydroxide before reduction and existed as a metal after reduction.

Preparation and properties of polyimide films codoped with barium and titanium oxides

Polyimide hybrid films containing bimetalic compounds were obtained by codoping poly(amic acid) with a barium and titanium precursor prepared from BaCO3, Ti(OBu)(4), and lactic acid followed by casting and thermal curing. FTIR, WAXD, and XPS measurements showed that barium and titanium precursor could be transformed to BaTiO3 at a temperature above 650 degreesC, while the mixed oxides were only found in hybrid films. The measurements of TEM and AFM indicated a homogeneous distribution of inorganic phase with particle sizes less than 50 nm. The hybrid films exhibited fairly high thermal stability, good optical transparency, and promising mechanical properties. The incorporation of 10 wt % barium and titanium oxide lowered surface and volume electrical resistivity by 2 and 5 orders, respectively, increasing dielectric constant from 3.5 to 4.2 and piezoelectric constant from 3.8 to 5.2 x 10(-12) c/N, relative to the nondoped polyimide film.

Preparation and characteristics of polyimide-TiO2 nanocomposite film

A sol-gel approach has been developed to prepare polyimide-TiO2, hybrid films fi om soluble polyimides and a modified titanium precursor. The rate of the hydrolysis reaction of titanium alkoxide can be controlled by using acetic acid as a modifier. FTIR and XPS indicated that TiO2, particles were well distributed in polyimide matrixes with particle size small per than 60 nm. Polyimide hybrid films having the TiO2, component less than or equal to 10% exhibited high thermal stability, high optical transparency and good mechanical properties and possessed higher dielectric constants than correspondingly polyimides. (C) 2000 Society of Chemical Industry.

Preparation and characterization of luminescent thin films doped with rare earth (Tb3+, Eu3+) complexes derived from a sol-gel process

Sol-gel derived luminescent thin films doped with rare earth (RE) complexes were prepared using an in-situ synthesis method with a two-step hydrolysis process and the luminescence spectra were measured. Fluorescence Lifetime and thermal stability were investigated. The results show that a broad excitation band indicates the formation of RE complexes in the solid thin films. RE ions, which are restrained in a silica matrix, present longer lifetime and higher thermal stability than that in DMF/PVB films containing the corresponding pure complexes. (C) 2000 Elsevier Science B.V. All rights reserved.

Preparation and properties of conducting polymer of doped polyaniline LB film

Stable monolayer of polyaniline doped with camphor sulfonic acid at the air-water interface has been obtained and has been successfully deposited by Langmuir-Blodgett technique onto CaF2 substrate. IR and UV-Vis-NIR spectra show that the doped molecules dedoped partially from the PANI backbone during the monolayer compression or deposition. Gas-sensing measurement indicates that the doped polyaniline LB film was sensitive to ethanol vapor at room temperature.

Processible nanomaterials with high conductivity and magnetizability. Preparation and properties of maghemite/polyaniline nanocomposite films

A versatile process employing anionic surfactants has been developed for the preparation of processible nanocomposite films with electrical conductivity and magnetic susceptibility. Maghemite (g-Fe2O3) nanoclusters (similar to 10 nm in size) are coated with 4-dodecyl- benzenesulfonic acid, and polyaniline (PAn) chains are doped with 10-camphorsulfonic acid. The coated nanoclusters and doped polymers are soluble in common solvents, and casting the solutions readily gives free-standing nanocomposite films with nanocluster contents as high as similar to 50 wt %. The g-Fe2O3/PAn nanocomposites show high conductivity (82-337 S cm(-1)) and magnetizability (up to similar to 35 emu/g g-Fe2O3).

Preparation and characterization of layered compound zirconium bis(monohydrogenphosphate)intercalated with rare earth complex

Layered compound zirconium bis(monohydrogenphosphate)(alpha-ZrP) intercalated with rare earth complex Eu(DBM)(3)phen was prepared. The pre-intercalation of p-methoxyaniline into alpha-ZrP makes the interlayer separation large enough to exchange PMA with europium complex, thus, the luminescent assembly was prepared. This was confirmed by X-ray diffraction, UV-visible spectra and elemental analysis. The fluorescence spectra and lifetime of the assembly were also presented.

Preparation and properties of a selenium-containing catalytic antibody as type I deiodinase mimic

Conversion of thyroxine (T-4) to 3,5,3'-triiodothyronine is an essential first step in controlling thyroid hormone action. Type I deiodinase (DI) can catalyze the conversion to produce the bulk of serum 3,5,3'-triiodothyronine. Acting as a mimic of DI, a selenium-containing catalytic antibody (Se-4C5) prepared by converting the serine residues of monoclonal antibody 4C5 raised against T4 into selenocysteines, can catalyze the deiodination of T4 with dithiothreitol (DTT) as cosubstrate. The mimic enzyme Se-4C5 exhibited a much greater deiodinase activity than model compound ebselen and another selenium-containing antibody Se-Hp4 against GSH. The coupling of selenocysteine with the combining pocket of antibody 4C5 endowed Se-4C5 with enzymatic activity. To probe the catalytic mechanism of the catalytic antibody, detailed kinetic studies were carried out in this paper. Investigations into the deiodinative reaction revealed the relationship between the initial velocity and substrate concentration. The characteristic parallel Dalziel plots demonstrated that Se-4C5-catalyzed reaction mechanism was ping-pong one, involving at least one covalent enzyme intermediate. The kinetic properties of the catalytic antibody were similar to those of DI, with K-m values for T-4 and DTT of approximately 0.8 muM and 1.8 muM, respectively, and a V-m value of 270 pmol per mg of protein per min. The activity could be sensitively inhibited by 6-propyl-2-thiouracil (PTU) with a K-i value of similar to 120 muM at 2.0 muM T-4 concentration. The PTU inhibition was progressively alleviated with the increasing concentration of added DTT, revealing that PTU was a competitive inhibitor for DTT.