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 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been demonstrated previously that isohydric hypercapnia (IH) does not affect agonist-induced tension development in pulmonary arteries. The aim of the present study was to examine the effects of IH on depolarisation-induced, steady state tension in the isolated rat pulmonary artery. Rings were submaximally contracted with high KCl under control conditions (5% CO(2)-95% air). IH was achieved by switching to a modified PSS (isosmotic substitution of NaHCO(3) for NaCl), equilibrated with 10% CO(2) in air. On switching to IH, a significant increase in mean (+/-SEM) tension (25.3+/-6.3% Tmax) was observed in endothelium intact rings (n=6). Endothelial removal significantly reduced this response. Non-specific inhibition of nitric oxide synthase (NOS) isoenzymes (L-NAME, 10(-3) M) abolished the IH-induced increase in tension while inhibition of neuronal NOS (TRIM, 10(-5) M) was without effect. The relaxant response to the nitric oxide donor sodium nitroprusside was similar in IH and control conditions. These results suggest that IH caused an endothelium-dependent increase in depolarisation-induced tension by reducing NO production.
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PMID:Hypercapnia-induced contraction in isolated pulmonary arteries is endothelium-dependent. 1085 24

An effective and facile approach for the preparation of multilayered nanostructure of gold nanorods (Au NRs) has been demonstrated. Linear polyethylenimine (LPEI) was selected as a polymeric adhesive layer, and an anionic polyelectrolyte poly(sodium styrenesulfonate) (PSS) was used as the linker of the positively charged Au NRs in multilayered nanostructure. They were deposited onto the LPEI-modified indium-doped tin oxide (ITO) substrate alternately using the layer-by-layer assembly technique via electrostatic interactions. The plasmonic property of the multilayered nanostructure of Au NRs is tunable by the controlled self-assembly process. FE-SEM was used to study the morphologies of the resulted substrates with Au NRs monolayer membrane and with Au NRs multilayered membrane. More importantly, it was found that the multilayered NRs films could be used as a surface-enhanced Raman spectroscopy (SERS) substrate for probing 4-aminothiophenol (4-ATP).
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PMID:Fabrication, characterization, and application in SERS of self-assembled polyelectrolyte-gold nanorod multilayered films. 1685 3

We describe the fabrication of multilayers and microcapsules with biologically designed targeting activity using chemoenzymatic synthesized carbohydrate-branched polyelectrolytes. A novel cationic d-galactose-branched copolymer [poly(vinyl galactose ester-co-methacryloxyethyl trimethylammonium chloride), PGEDMC] is alternated with poly(styrene sulfonate) (PSS) to form thin multifilms by the layer-by-layer (LbL) technique on such different solid surfaces as quartz slides, poly(ethylene terephthalate) (PET) films, silicon wafers, and polystyrene (PS) microparticles. The experimental protocols were first optimized on flat, smooth silica substrates using UV-vis, contact angle, and atomic force microscopy (AFM) measurements. The film properties of PGEDMC/PSS multilayers are modified by varying polyelectrolyte concentration, ionic strength, and counteranion types. Hollow capsules were formed after the removal of colloidal templates; transmission (TEM) and scanning (SEM) electron microscopy were used to verify the LbL process integrity. PGEDMC/PSS planar films and capsules carrying beta-galactose as recognition signals have specific recognition abilities with peanut agglutinin (PNA) lectin rather than concanavalin A (Con A) lectin observed by fluorescence spectroscopy.
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PMID:Bioactive galactose-branched polyelectrolyte multilayers and microcapsules: self-assembly, characterization, and biospecific lectin adsorption. 1698 63

We describe the construction of hepatic-targeting microcapsules by self-assembly of chemo-enzymatic synthesized poly(vinyl galactose ester-co-methacryloxyethyl trimethylammonium chloride) (PGEDMC) containing galactose branches, which can be specifically recognized by membrane bound galactose receptors (ASGPR), for acyclovir (ACV) controlled release system. Alternate deposition of PGEDMC and poly(sodium 4-styrenesulfonate) (PSS) was carried out on ACV microcrystals. It was revealed that the drug release rate decreases with the increase of coated layer number and a microcapsule-drying treatment would enhance the sustained release effect probably because of a multilayer shrink and tightness during the process. The complete release of ACV yielded a hollow PGEDMC/PSS multilayered network with favorable integrity and nano-thickness by TEM and SEM. The potential targetability of the system was proved in vitro by PNA lectin recognition. Lectin hardly adsorbed on the film where the outmost layer was a polyanion or a polycation without galactose component. Whilst the galactose-containing layer (PGEDMC) was the outmost layer, a significant lectin combination was observed. This technique could provide a promising way to encapsulate and deliver various target substances in biological and pharmaceutical applications.
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PMID:Hepatic-targeting microcapsules construction by self-assembly of bioactive galactose-branched polyelectrolyte for controlled drug release system. 1793 43

In this article, a layer-by-layer (LbL)-assembled coordination multilayer on planar and 3D substrates was explored by the alternate deposition of a transition-metal-containing polyelectrolyte and a ligand-containing polymer via the formation of complexes. The metal-ligand coordination between the building blocks of Co(2+)-exchanged poly(styrene sulfonate) (PSS) and poly(4-vinyl pyridine) (P4 VP) has been demonstrated using UV-vis, FTIR, and XPS. The film thickness, structure, and morphology as well as the wettability as a function of bilayer number have been systematically investigated by profilometry, SEM, AFM, and contact angle analyzers. For the purpose of separation applications, the metal-ligand-coordinated multilayer was assembled on both flat sheet and hollow fiber polymeric porous substrates using a dynamic pressure-driven LbL technique. It was demonstrated that the LbL-assembled PSS(Co)(1/2)/P4 VP multilayer membrane had high dehydration performance with respect to different solvent-water mixtures; it also had aromatic compound permselectivity from aromatic-aliphatic hydrocarbons and water-softening capacity. Meanwhile, the successful assembly of multilayers on hollow fibers indicates that the dynamic pressure-driven LbL technique is a unique approach to the construction of multilayers on porous 3-D substrates. Therefore, the metal-ligand-coordinated self-assembly could emerge as a powerful technique for the preparation of a range of separation membranes in different types of modules.
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PMID:Construction of metal-ligand-coordinated multilayers and their selective separation behavior. 2035 9

Electrostatic layer-by-layer assembly was the basis for the synthesis of multilayer nanorod/polymer composite films. Cationic and water-soluble CdSe nanorods (NRs) were synthesized and partnered with anionic polymers including poly(sodium 4-styrenesulfonate) (PSS) and two polythiophene-based photoactive polymers, sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate (PTEBS) and poly[3-(potassium-6-hexanoate)thiophene-2,5-diyl] (P3KHT). Controlled multilayer growth is shown through UV-vis spectroscopy, cross-sectional SEM and surface analytical techniques including atomic force microscopy. The formation of an intimate nanorod/conducting polymer bulk heterojunction is confirmed through cross-sectional SEM, TEM, and scanning Auger analysis. A series of photovoltaic devices was fabricated on ITO electrodes using CdSe NRs in combination with PTEBS or P3KHT. A thorough device analysis showed that performance was limited by low short circuit current although charge transfer was confirmed in the ELBL nanocomposite thin films.
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PMID:Electrostatic layer-by-layer assembly of CdSe nanorod/polymer nanocomposite thin films. 2035 38

A stretchable e-textile was fabricated by simply soaking Spandex fabric in a conductive polymer aqueous dispersion, PEDOT-PSS. The resulting conductive fabric had an average conductivity of 0.1 S/cm. Subjecting the fabric to more than one soaking step increased the conductivity of the fabric up to ca. 2.0 S/cm resulting in a 33% faster switching speed. This simple methodology is not limited to Spandex (50% nylon/50% polyurethane). Several other fabric compositions were investigated for their conductivity via this process, including 100% cotton, 60% cotton/40% polyester, 95% cotton/5% Lycra, 60%polyester/40% rayon, 100% polyester, and 80% nylon/20% Spandex, listed in order of decreasing hydrophilicity. Those fabrics with higher water uptake resulted in higher conductivities upon soaking in PEDOT-PSS. Electrochromic polymers coated on the fabric could be switched between their different colored states, even upon stretching of the Spandex. SEM revealed that the electrochromic polymer coated on the substrate separated under stretching, uncovering the color of the base conducting fabric. It was found that the PEDOT-PSS was not a film on the Spandex but rather homogenously dispersed nanoparticles within the fabric matrix forming a percolated network.
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PMID:Conductivity trends of PEDOT-PSS impregnated fabric and the effect of conductivity on electrochromic textile. 2048 42

Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed.
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PMID:Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon. 2085 47

Polythiophene/poly(sodium 4-styrene sulfonate) (PT/PSS) composite nanoparticles having different particle size were prepared by Fe(3+)-catalyzed oxidative polymerization in aqueous medium. This facile method includes a FeCl3/H2O2 (catalyst/oxidant) combination system, which guarantees a high conversion (more than 95%) of thiophene monomers in various concentration of poly(styrene sulfonate) (PSS) with only a trace of FeCl3. Particle size of PT/PSS composite nanoparticles decreased from 134 nm to 26 nm as the concentration of PSS and H2O2 increased, and which was confirmed by SEM and CHDF analyses. The poly(ethylene terephthalate) (PET) film coated with PT/PSS was transparent and showed a high conductivity in a dried state. The sheet resistivity decreased as the ratio of PT to PSS increased. Photoluminescence property of the PT/PSS composite nanoparticles was also investigated.
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PMID:PSS resin-fortified polythiophene nanoparticles for highly transparent conducting films. 2113 30

Different graphene inks have been synthesized by chemical methods. These uniform dispersions were stabilized by various functional groups such as room temperature ionic liquid, polyaniline, polyelectrolyte (poly[2,5-bis(3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt) and poly(styrenesulfonate) (PSS). The dispersions can be easily cast into high-quality, free-standing films but with very different physiochemical properties such as surface tension and adhesion. SEM and AFM methods have been applied to have a detailed study of the properties of the inks. It is found that graphenes modified by p-type polyaniline show the highest surface tension. Diverse surface adhesive properties to the substrate are also found with various functional groups. The different viscoelasticities of graphene inks were related to the microscopic structure of their coating layer and subsequently related to the configuration, chemistry and molecular dimensions of the modifying molecules to establish the property-structure relationship. Modifications of graphene inks made from chemical reduction cannot only enable cost-effective processing for printable electronics but also extend the applications into, for example, self-assembly of graphene via bottom-up nano-architecture and surface energy engineering of the graphenes. To fabricate useful devices, understanding the surface properties of graphene inks is very important. It is the first paper of this kind to study the surface tension and adhesion of graphene influenced by different functional groups.
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PMID:Properties of graphene inks stabilized by different functional groups. 2150 55


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