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.     

Synthesis of epigallocatechin trimer, (epigallocatechin)2-epicatechin,and (epigallocatechin)2-catechin via a Lewis acid mediated one-pot condensation and their antitumor activities in prostate cancer cells

Syntheses of epigallocatechin trimer, (epigallocatechin)₂-epicatechin and (epigallocatechin)₂-catechin were achieved. The key condensation to form the proanthocyanidin trimer derivatives was accomplished in a one-pot procedure using a dimeric epigallocatechin electrophile, which was prepared in situ by self-condensation of an epigallocatechin derivative, and an epigallocatechin, epicatechin, or catechin derivative as the nucleophile in the presence of a Lewis acid. The epigallocatechin monomer to trimer compounds containing a pyrogallol group significantly suppressed cell proliferation in PC-3 prostate cancer cells.     

A new method of using supercritical carbon dioxide as a green solvent for synthesis and purification of 5,5‴-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2‴-quaterthiophene,which is one of n-type organic semiconducting materials

We have investigated synthesis as well as purification of 5,5?-bis(tridecafluorohexyl)-2,2′:5′,2″:5″,2?-quaterthiophene (BFH-4?T, n-type organic semiconducting material) using supercritical carbon dioxide (scCO₂) as a green solvent. BFH-4T was obtained in good selectivity and high yield by TDAE/PdCl₂-catalyzed reductive coupling reaction of 5-bromo-5′-(tridecafluorohexyl)-2,2′-bithiophene in scCO₂. We have also successfully established purification of the reaction mixture by passing scCO₂ in the reaction vessel. The product was yellow powder of BFH-4T with purity of more than 99% and Pd catalyst was not contained.     

Preparation of thermo- and redox-responsive branched polymers composed of three-armed oligo(ethylene glycol)

We herein report the preparation of thermo- and redox-responsive branched polymers by the condensation reaction of three-armed oligo(ethylene glycol) (trisOEG) and cystamine (CA). The prepared branched polymers exhibited a soluble–insoluble transition at a lower critical solution temperature (LCST) and formed coacervate droplets through a liquid–liquid phase separation process. We then demonstrated control of the LCSTs of the branched polymers by varying the feed ratio of CA and the surrounding salt concentration close to body temperature. In addition, the trisOEG-cys _x polymer formed coacervate droplets above the LCST, in which hydrophobic molecules were condensed. The redox response of the branched polymers was also investigated. Interestingly, the branched polymers degraded to low-molecular-weight materials (i.e., trisOEG) in the presence of dithiothereitol as a reducing agent through cleavage of the disulfide bond of CA. This facile preparation of branched polymers is expected to be valuable in the context of functional biomedical materials and modifiers for materials surfaces, such as the bases for drug delivery carriers and separation materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2623–2629     

Element geochemistry of Holocene sediment and paleoenvironmental change in the Changjiang Estuary

Analyses of 41 elements reveal that Holocene sediments in the Changjiang Estuary bear regular elemental compositions in different sedimentary environments, and Holocene sediments came mainly from the Changjiang River based on compositions of REEs and most trace elements. Some heavy metals are more enriched in the surface sediment than in the deltaic sediments, reflecting human impact. Elemental compositions of the river channel sediment are related to the influence of proximal sediments. Sedimentary environments exert some influences on elemental compositions. Some chemical indices can be used to record chemical weathering undergone by the Changjiang sediment and environmental change.     

Inhibition of acetylcholinesterase activity by essential oil from Citrus paradisi

Inhibition of acetylcholinesterase (AChE) activity by essential oils of Citrus paradisi (grapefruit pink in USA) was studied. Inhibition of AChE was measured by the colorimetric method. Nootkatone and auraptene were isolated from C. paradisi oil and showed 17-24% inhibition of AChE activity at the concentration of 1.62 microg/mL.     

Complex formation of amphiphilic polymers with azo dyes and their photoviscosity behavior

The hydrophobic interaction of amphiphilic copolymers, which contain 2-hydroxyethyl methacrylate(HEMA) and 1vinyl-2-pyrrolidone (VPy), with Methyl Orange (MO) was compared with that of HEMA-acrylamide (AAm) copolymers to deduce the correlation between their complexation ability in a photochromic azo dye and the photoviscosity effect in aqueous copolymer/dye complex solution. On the basis of the dialysis data and fluorometric analysis it appeared that the complexation dependence on HEMA content in the copolymers was due to the hydrophobic interaction between the polymer and the dye. For a comparable HEMA content AAm copolymers bound less MO than VPy copolymers. It was confiied by photoviscosity measurements that the conformation of the complex composed of photochromic azo dye and HEMA copolymer changed reversibly in response to the photo- and thermal isomerization of the dye. In HEMA-AAm copolymer systems the photoviscosity effect was small compared with that of HEMA-VPy copolymer systems. From these results it was concluded that the complexation ability of polymers due to the hydrophobic interaction was an important factor in producing a large photoinduced conformational change in water.     

Palladium(O)-catalyzed allylic alkylation and amination of allylic phosphates

Allyl diethyl phosphates (1) can be easily substituted with malonates and amines in the presence of palladium(O) catalyst. Synthetic utility of the reaction is demonstrated by the sequential amination-amination and alkylation-amination of (Z)-4-acetoxybut-2-enyl diethyl phosphate (1b) with high regio- and stereoselectivity.     

NAD(P)+-NAD(P)H model. 38. Reduction of aldehyde by 1,4-dihydroquinolin derivative

Benzaldehyde are reduced to benzyl alcohol by a model compound of NAD(P)H almost quantitatively. Reductions of some other aldehydes are also mentioned.