Synthesis of polymers having a phospholipid polar group connected to a poly(oxyethylene) chain and their protein adsorption-resistance properties

New methacrylates having a phospholipid polar group which was connected to various lengths of poly(oxyethylene) chains to form a polymerizable group (MEOnPC) were synthesized. The MEOnPC could polymerize with n-butyl methacrylate (BMA) in ethanol using a conventional radical polymerization technique. The unit mole fraction of MEOnPC in the polymer corresponded to that in the feed monomer solution. The MEOnPC polymers were soluble in ethanol, insoluble in water, but swelled in water and became hydrated. On the surface of a poly(BMA) membrane coated with MEOnPC, the phosphorylcholine groups of the MEOnPC unit present were determined by x-ray photoelectron spectroscopy. As a fundamental evaluation for biomedical materials, adsorption of one of the plasma proteins, fibrinogen, on acrylic beads coated with the MEOnPC polymers was evaluated. The amount of fibrinogen adsorbed on the MEOnPC polymer was smaller than that on the original acrylic beads, poly(BMA) and poly(2-hydroxyethyl methacrylate). The increase in the MEOnPC unit mole fraction in the polymer showed more effective protein adsorption-resistant properties. © 1996 John Wiley & Sons, Inc.     

Linear polybiurets: Facile synthesis and characteristic properties

Linear polybiurets have been synthesized by polyaddition of benzyloxyamine and diisocyanates, and properties of the novel polymeric materials have been elucidated. Prior to polymerization, model reactions between benzyloxyamine and phenyl isocyanate were examined in detail and proved to be controlled by the molar ratio of reagents and by catalysts to give the urea (1:1 adduct) and/or biuret (1:2 adduct). Under appropriate conditions, the biuret was synthesized in a quantitative yield. Polymerization of equimolar amounts of benzyloxyamine and diphenylmethane or hexamethylene diisocyanate proceeded smoothly to give polybiurets with inherent viscosities up to 0.52 dL/g. The benzyl group of the model biuret and polybiuret could be removed by catalytic hydrogenation. Both the N-benzyloxy-type and N-hydroxy-type polybiurets showed excellent solubility in common organic solvents. The two kinds of polybiurets as well as model biurets adsorbed metal cations efficiently. The N-hydroxybiuret structure exhibited particularly high affinity for iron(III) and was useful for selective removal of iron from metal cation mixtures. © 1996 John Wiley & Sons, Inc.     

Conformationally Flexible Biphenyl‐phosphane Ligands for Ru‐Catalyzed Enantioselective Hydrogenation

Stereomutation of a BIPHEP/RuCl ₂ /diamine complex (shown schematically) is possible because of the conformational flexibilty of BIPHEP ligands. The result is an asymmetric activation in the Ru‐catalyzed hydrogenation of carbonyl compounds to optically active alcohols. Whereas a racemic BINAP/RuCl₂ complex with a chiral diamine activator gives a 1:1 mixture of two diastereomers, unequal amounts of the diastereomers can be produced from a BIPHEP/RuCl₂ complex and a chiral diamine. Ar=3,5‐dimethylphenyl, BINAP=2,2′‐bis(diphenylphosphanyl)‐1,1′‐binaphthyl, BIPHEP=2,2′‐bis(diarylphosphanyl)biphenyl.     

BDH-TTP as a Structural Isomer of BEDT-TTF,and Its Two-Dimensional Hexafluorophosphate Salt

Metallic behavior down to low temperature is shown by charge transfer salts of BDH-TTP ( 1 ), a structural isomer of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF). In the case of (BDH-TTP)₂PF₆ this behavior is attributed to the structure, which is made up of κ-type sheets of BDH-TTP donor molecules and sheets of PF₆⁻ anions.     

An efficient synthesis of N-tert-butoxycarbonyl-O-cyclohexyl-L-tyrosine

A facile and efficient synthesis of N-tert-butoxycarbonyl-O-cyclohexyl-L-tyrosine [Boc-Tyr(Chx)-OH] is described. Boc-Tyr-OH was treated with NaH in dimethylformamide and then with 3-bromocyclohexene to give N-Boc-O-(cyclohex-2-enyl)-L-tyrosine [Boc-Tyr(Che)-OH] in 70% yield. Hydrogenation of Boc-Tyr(Che)-OH over PtO2 afforded Boc-Tyr(Chx)-OH in almost quantitative yield. The highest yield was achieved when a side product in the synthesis of Boc-Tyr-OH, Boc-Tyr(Boc)-OH, was not removed, because it was also converted to Boc-Tyr(Che)-OH without any additional manipulations. The new synthetic method described here is convenient for practical use, and would facilitate the widespread use of the Chx group for the hydroxy-protection of Tyr.     

Direct Oxidation of Propylene with Molecular Oxygen Over Ti-Modified Sulfated Zirconia Catalyst, 2. In Situ Diffuse Reflectance FT-IR Study

During the reaction of propylene with O₂, in situ Diffuse Reflectance FT-IR measurements were performed over Ti-modified SZ and SZ catalysts. Without O₂, the main bands characteristic of (branched) hydrocarbons, formed by oligomerization leading to, finally, carbonaceous residue, appeared within the range of 3900-2750 cm^-1, which was affected by the bands of surface OH groups. Investigation of these IR bands showed the role of molecular oxygen not only to limit the formation of carbonaceous species on the catalyst surface, but also to form oxygenates and these findings were in good agreement with the results of catalytic reaction.     

Engineering Chiral Catalysts through Asymmetric Activation and Super High Throughput Screening (SHTS)

A conceptually new strategy for asymmetric catalysis, namely asymmetric activation, in which a chiral activator selectively activates one enantiomer of a racemic chiral catalyst, and a highly efficient screening system for finding the most effective catalysts, namely super high throughput screening (SHTS), by which the reaction can be conducted in parallel and the ee% of the product is allowed to determine within minutes, are summarized in the present account. It is reasonable to believe that SHTS technique combined with asymmetric activation or deactivation principle will provide a very powerful methodology for finding the new catalysts and the best catalyst tuning for asymmetric reactions.     

Induced chiral helical effect on the main chain of aliphatic polyacetylenes

11‐Dodecyn‐1‐ol as an achiral, aliphatic, monosubstituted acetylene was copolymerized with cholesteryl 3‐butynyl carbonate as a chiral, aliphatic, monosubstituted acetylene with Rh(nbd)[B(C₆H₅)₄] (nbd = norbornadiene) in tetrahydrofuran. The main chain of the obtained copolymers seemed to be mainly composed of the cis‐type structure. The backbone π–π* transition of these copolymers showed significant circular dichroism (CD), indicating an excess of one‐handed helical conformation. These CD signals were varied with the contents of the cholesteryl units in the copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 913–917, 2001     

Pipette tip biosensors for bacterial double-stranded DNA using bioluminescence induced by zinc finger luciferase

The authors describe a pipette type of biosensor for detecting target genes and using a zinc finger protein fused to luciferase (ZF luciferase). The ZF protein binds to a specific DNA sequence, and the target double-stranded (ds) DNA can be detected by monitoring the enzymatic activity of ZF luciferase. A small avidin-immobilized reaction plate is placed on a plastic pipette tip (referred to as Biologi tip). The dsDNA detection procedures are carried out by using a programmable dispensing robot equipped with a photodetector. These procedures include (a) the aspiration of an analyte to capture the biotinylated target dsDNA (a product of a polymerase chain reaction) on the small reaction plate inside the pipette tip, (b) the introduction of ZF luciferase and luciferin into the pipette tip, and (c) migration of the pipette tip to the detection port to measure bioluminescence on the small reaction plate. The emission originating from luciferase activity is observed on the reaction plate containing immobilized biotin-tagged target dsDNA, whereas plates containing non-target or biotinylated single-stranded DNA only do not yield a signal. The intensity of emission increases proportionally to the concentration of dsDNA, and the detection limit of the target dsDNA is as low as 62 pM. An actual genomic DNA sample from Escherichia coli O157 was successfully detected by this automatic analyzer using the Biologi tip equipped with a reaction plate. This indicates that this system has a large potential for practical applications, including in particular point-of-care analyses in hygiene control, food safety testing, and clinical diagnosis.

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Graphical abstract A pipette-type biosensor was developed to detect target genes using a luciferase-fused zinc finger protein, where a small NeutrAvidin-immobilized reaction plate was placed on the tip, and the biotinylated target double-stranded DNA was detected by monitoring the bound luciferase activity.