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Results for “Polystyrenes”

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PubMed2002

Synthesis of [difluoro-(3-alkenylphenyl)-methyl]-phosphonic acids on non-crosslinked polystyrene and their evaluation as inhibitors of PTP1B.

A series of [difluoro-(3-alkenylphenyl)-methyl]-phosphonates were prepared on non-crosslinked polystyrene, a soluble polymer support. After cleavage from the support, the resulting phosphonic acids were examined for inhibition with protein tyrosine phosphatase 1B. Compound 20, bearing an alpha,beta-unsaturated allyl ester moiety, was the most potent of this series of compounds, being a reversible, competitive inhibitor with a K(i) of 8.0+/-1.4 microM.

Binding, Competitive↗

PubMed2001

Immobilisation on polystyrene of diazirine derivatives of mono- and disaccharides: biological activities of modified surfaces.

The potential of surface glycoengineering for biomaterials and biosensors originates from the importance of carbohydrate-protein interactions in biological systems. The strategy employed here utilises carbene generated by illumination of diazirine to achieve covalent bonding of carbohydrates. Here, we describe the synthesis of an aryl diazirine containing a disaccharide (lactose). Surface analysis techniques [X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToF-SIMS)] demonstrate its successful surface immobilisation on polystyrene (PS). Results are compared to those previously obtained with an aryl diazirine containing a monosaccharide (galactose). The biological activity of galactose- or lactose-modified PS samples is studied using rat hepatocytes, Allo A lectin and solid-phase semi-synthesis with alpha-2,6-sialyltransferase. Allo A shows some binding to galactose-modified PS but none to lactose-modified surfaces. Similar results are obtained with rat hepatocytes. In contrast, sialylation of lactose-modified PS is achieved but not with galactose-modified surfaces. The different responses indicate that the biological activity depends not only on the carbohydrate per se but also on the structure and length of the spacer.

Animals↗

PubMed2003

Resonance energy transfer from dibucaine to acriflavine in polystyrene latex dispersions.

Resonance energy transfer from dibucaine (DC) to acriflavine (AF) has been investigated both in homogeneous aqueous solutions and in polystyrene latex dispersions. The energy transfer reaction is observed by monitoring fluorescence quenching of DC as well as sensitized emission of AF. It is found that the energy transfer from DC to AF is remarkably enhanced on going from the aqueous homogeneous solution to the latex dispersion. This is mainly attributed to the fact that both the donor and acceptor are effectively adsorbed onto the latex particles, as evidenced by the measurement of adsorption isotherms. From the adsorption experiments, it is also elucidated that electrostatic interaction is significant at low DC concentration, while hydrophobic interaction dominates at the higher concentration especially at higher pH.

Acriflavine↗

PubMed1999

Effect of surface roughness on proliferation and alkaline phosphatase expression of rat calvarial cells cultured on polystyrene.

Rough-surfaced substrates made by a variety of methods have been shown to influence osteoblast proliferation and differentiation. The purpose of this study is to confirm the role of surface roughness in promoting osteoblastic differentiation using tissue culture polystyrene as substrate, by excluding factors other than roughness. Immature osteogenic cells derived from fetal rat calvariae were cultured on the plastic cover strips having varied degrees of roughness created by treatment with four kinds of grinding paper of different particle sizes. The proliferation and gene expression of alkaline phosphatase (ALP) and osteocalcin of the calvarial cells increased on the rough-surfaced cover strips. These levels increased in response to the increase in the degree of surface roughness up to 0.8 microm of average roughness and then decreased to the level observed for the smooth surface. These results demonstrate that the surface roughness itself caused increases in osteoblastic proliferation and differentiation in cell cultures.

Alkaline Phosphatase↗

PubMed2000

Quaternized trimethylaminated polystyrene-coated zirconia as a strong anion exchange material for HPLC.

The synthesis and characterization of a new, base-stable, strong anion exchange phase by amination of polystyrene-coated zirconia (PS-ZrO2) are described. Even though the ion exchange capacity of the quaternized trimethylaminated PSZrO2 (QTMA-PS-ZrO2) is only 0.07 mequiv/g, it is able to separate various inorganic anions, benzoic acid derivatives, and nucleotides in their deprotonated states. The effects of ionic strength, eluent pH, and counterion type are discussed. In the presence of both phosphate and fluoride ions in the eluent, band broadening caused by Lewis acid/base interactions between zirconia and analytes is greatly suppressed. The mixed retention modes (ion exchange, hydrophobic interaction, and Lewis acid/base interactions) on QTMA-PS-ZrO2 offer a different selectivity toward various anionic analytes than do other zirconia- and nonzirconia-based ion exchangers.

Antiporters↗

PubMed1993

Stabilization of reactive species within polystyrene divinylbenzene polymer networks.

The effect of cross-linking, surface area, and porous nature of modified polystyrene-divinylbenzene (STY-DVB) reagents has been investigated. The supports were prepared via two techniques and modified to contain various chemical functionalities. These reagents were used in an on-line reactor for automated derivatization of amines in HPLC. The reproducibility of the response vs the physical nature of the porous support and the chemical functionality was determined. The ability to stabilize highly reactive acylating reagents toward high concentrations of aqueous base was found to be a complex interaction of pore size distribution, percent cross-linking, surface area, and absolute loading of the analytical reagent on the porous support.

Chromatography, High Pressure Liquid↗

PubMed1994

Pulsed-field capillary electrophoresis: optimizing separation parameters with model mixtures of sulfonated polystyrenes.

The electrophoretic transport of high molecular weight charged solutes, both flexible and stiff polymers, has been studied by capillary electrophoresis under constant-field and pulsed-field conditions. Sulfonated polystyrenes were used as model solutes in different entangled polymer solutions. First, changes of the end-to-end distance vectors of flexible polymers were examined through the mobility/potential-gradient curves. Under pulsed-field conditions, the influence of different pulse shapes, frequencies, and amplitudes of forward and backward pulses on the electrophoretic mobilities of model solutes was studied. Resolution of the mixture components was strongly affected by changes in frequency of both sine-wave and square-wave pulses. The experimental results obtained under pulse-field conditions are roughly in agreement with the existing theories of electrophoretic transport.

Electrophoresis↗

PubMed2003

Low-attomole electrospray ionization MS and MS/MS analysis of protein tryptic digests using 20-microm-i.d. polystyrene-divinylbenzene monolithic capillary columns.

This work explores the use of 20-microm-i.d. polymeric polystyrene-divinylbenzene monolithic nanocapillary columns for the LC-ESI-MS analysis of tryptic digest peptide mixtures. In contrast to the packing of microparticles, capillary columns were prepared, without the need of high pressure, in fused-silica capillaries, by thermally induced in situ copolymerization of styrene and divinylbenzene. The polymerization conditions and mobile-phase composition were optimized for chromatographic performance leading to efficiencies over 100000 plates/m for peptide separations. High mass sensitivity (approximately 10 amol of peptides) in the MS and MS/MS modes using an ion trap MS was found, a factor of up to 20-fold improvement over 75-microm-i.d. nanocolumns. A wide linear dynamic range (approximately 4 orders of magnitude) was achieved, and good run-to-run and column-to-column reproducibility of isocratic and gradient elution separations were found. As samples, both model proteins and tissue extracts were employed. Gradient nano-LC-MS analysis of a proteolytic digest of a tissue extract, equivalent to a sample size of approximately 1000 cells injected, is presented.

Amino Acid Sequence↗

PubMed2004

HPLC and MALDI-TOF MS analysis of highly branched polystyrene: resolution enhancement by branching.

Temperature gradient interaction chromatography (TGIC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were applied for the characterization of highly branched polystyrenes (PS) prepared by linking living polystyryl anions using 4-chlorodimethylsilylstyrene. Reversed-phase (RP)-TGIC showed an unexpectedly high resolution according to the number of branches despite significant overlap of the molecular weight as confirmed by MALDI-TOF MS. The enhancement of the resolution is ascribed to the contribution of the nonpolar groups in the branched PS: the dimethylsilyl groups in the branching unit as well as the sec-butyl initiator groups. As the number of branches increases, the number of nonpolar groups increases, which in turn increases the RP-TGIC retention synergistically with increasing molecular weight. In contrast, a poorer resolution was found in normal-phase-TGIC, in which the nonpolar groups reduce the retention. The resolution in RP-TGIC appears superior to that of liquid chromatography at the chromatographic critical condition (LCCC) of PS. It is seemingly due to the synergistic contribution of the incremental PS molecular weight to the functionality in the branched PS in RP-TGIC while only the functionality contributes to the separation in LCCC. This type of resolution enhancement could be utilized efficiently for the analysis of highly branched polymers such as dendrimers or hyperbranched polymers.

Chromatography, High Pressure Liquid↗

PubMed2000

A comparative study of the chromatographic selectivity of polystyrene-coated zirconia and related reversed-phase materials.

The chromatographic selectivities of polystyrene-coated zirconia (PS-ZrO2) have been investigated in detail by means of homologue series retention studies and studies of a variety of nonpolar aromatic positional isomers. This material has been compared to polybutadiene-coated zirconia, octadecyl- and phenyl-bonded silica, and polymer-based reversed phases. In addition, the separations of a wide variety of compound classes on PS-ZrO2 were compared with those on other aromatic and aliphatic RPLC phases. The PS-ZrO2 material exhibits substantial differences in selectivity toward nonpolar and polar analytes as compared to other phases, especially with respect to polybutadiene-coated zirconia (PBD-ZrO2). On PS-ZrO2, polynuclear aromatic hydrocarbons (PAHs) are retained much more than are alkylbenzenes, whereas on PBD-ZrO2 the opposite is observed. In addition, PS-ZrO2 has much greater selectivity than does PBD-ZrO2 for the separation of structural isomers which differ in the position of phenyl groups. In general, even though the carbon content of PS-ZrO2 is much lower than that of conventional reversed-phase materials, such as octadecyl-bonded silica (C18-SiO2), polar analytes exhibit sufficient retention and differential selectivity on PS-ZrO2 that resolution comparable to that on C18-SiO2 can be obtained but with substantially improved analysis times.

Chromatography, Liquid↗

PubMed2000

Integration of an immunosorbent assay system: analysis of secretory human immunoglobulin A on polystyrene beads in a microchip.

An immunosorbent assay system was integrated into a glass microchip. Polystyrene beads were introduced into a microchannel, and then human secretory immunoglobulin A (s-IgA) adsorbed on the bead surface was reacted with colloidal gold conjugated anti-s-IgA antibody and detected by a thermal lens microscope. The scale merits of liquid microspace on the molecular behavior remarkably contributed to reduced assay time. The integration cut the time necessary for the antigen-antibody reaction by 1/90, thus shortening the overall analysis time from 24 h to less than 1 h. Moreover, troublesome operations required for conventional immunosorbent assays could be replaced by simple operations.

Antigen-Antibody Reactions↗

PubMedDate not supplied

Capture of HIV-1 gp120 and virions by lectin-immobilized polystyrene nanospheres.

A lectin such as concanavalin A (Con A) was immobilized on the surfaces of poly(methacrylic acid) branches covered with polystyrene nanospheres with a diameter of 360 nm, which were obtained by the free radical copolymerization of styrene with the poly(tert-butylmethacrylate) macromonomer, followed by hydrolysis. Using Con A-immobilized (0.3 microgram/cm2) nanospheres, the interaction of the nanospheres with HIV-1 was determined by the reduction of the gp120 level and the viral infectivity of the HIV-1 suspensions after a 60 min incubation at room temperatures. Con A-immobilized nanospheres achieved a 95 and a 77% reduction of the gp120 level and the infectivity at a concentration of 0.5 mg/mL, respectively, indicating the effective capture of the gp120 and the virions.

Concanavalin A↗

PubMed2000

Polyampholyte gelatin adsorption to colloidal latex: pH and electrolyte effects on acrylic and polystyrene latices.

Polyampholytic gelatin adsorption onto two model, aqueous colloidal dispersions of like size and surface charge density, but varying hydrophobicity are reported. Adsorption isotherms and hydrodynamic layer thickness of the adsorbed gelatin layer are reported for variations of solution pH (above the gelatin IEP) and electrolyte concentration. A van't Hoff analysis of the temperature dependence of the dilute-limiting adsorption equilibrium constants provides evidence for adsorption driven by electrostatic polarization to like-charged surfaces, as well as additional hydrophobic interactions with polystyrene colloidal surfaces. It is demonstrated how these measurements can be used to predict the perikinetic stability of gelatin-coated colloidal latices and, hence, are useful for the rational formulation of dispersions containing polyampholytes.

Acrylates↗

PubMedDate not supplied

Amphiphilic block copolymers as bile acid sorbents: 2. Polystyrene-b-poly(N,N,N-trimethylammoniumethylene acrylamide chloride): self-assembly and application to serum cholesterol reduction.

This paper presents morphological studies and preliminary bile salt binding properties of the new amphiphilic diblock copolymer polystyrene-b-poly(N,N,N-trimethylammoniumethylene acrylamide chloride) (PS-b-PTMEACl)(1) (see Figure 1), a derivative of PS-b-poly(tert-butylacrylate) (PS-b-PtBuA). In an aqueous environment, PS-b-PTMEACl forms simple spheres (approximately 20 nm diameter), large compound micelles (>100 nm diameter), and larger, more complex architectures as presented and discussed below. The colloidal stability with respect to sodium chloride and as a function of particle concentration is also considered. Finally, PS-b-PTMEACl aggregates were prepared and tested as an alternative to the commercially available bile salt sequestrant resins that target coronary heart disease due to elevated cholesterol levels. Electron micrographs were employed to visualize the colloid-based polyelectrolyteminus signbiosurfactant interaction and chromatographic separation analytical methods were used to quantify the sequestration. The results indicate that although at this preliminary stage they require laborious preparation, self-assembled aggregates may present an interesting alternative to the clinically used bile salt sequestrants.

Bile↗

PubMedDate not supplied

Surface plasmon resonance study of carbohydrate-carbohydrate interaction between various gangliosides and Gg3-carrying polystyrene.

Carbohydrate-carbohydrate interactions between Gg3 trisaccharide-carrying polystyrene (PN(Gg3)) and monolayers of several glycosphingolipids (GSLs) were quantitatively investigated by surface plasmon resonance techniques. PN(Gg3) was adsorbed onto a GM3 monolayer strongly and specifically with an apparent affinity constant of K(a) = 2.5 x 10(6) M(-1), and the apparent affinity constants onto GSLs decreased in the following order: GM3 > LacCer > (KDN)GM3 approximately GlcCer > GM2 approximately GD3 approximately GM4 > GM1 approximately 2,6-isoGM3 > ceramide. These results suggest that PN(Gg3) recognizes not only some specified portions of GM3 but also the trisaccharide as a whole. On the other hand, PN(Lac) and PN(Cel) were bound to GSLs less strongly (K(a) approximately 10(4) M(-1)) and less selectively. The kinetic analysis revealed that the selectivity in the adsorption of PN(Gg3) onto the GM3 monolayer is dominated by the faster adsorption rate.

Carbohydrate Sequence↗

PubMedDate not supplied

Catalytic peptide synthesis by trypsin modified with polystyrene in chloroform.

Trypsin was modified with a hydrophobic synthetic polymer, polystyrene. The attachment was achieved by first coupling free amines in the trypsin with azo-bis(4-cyano-valeric acid) and then irradiating the product in the presence of styrene. Decomposition of the azo structure provided free radical initiation of styrene polymerization, with the trypsin thus becoming part of the end group for the polymer chain initiated. That the modified trypsin retained catalytic activity when dissolved in chloroform was demonstrated by using it to catalyze the formation of a peptide linkage between amino acids. The catalytic reaction was stereoselective.

Animals↗

PubMedDate not supplied

Photoimmobilization of insulin onto polystyrene dishes for protein-free cell culture.

Photoreactive insulin was synthesized by coupling with azidobenzoic acid. The insulin derivative was immobilized onto the wells of polystyrene culture plates by photoir-radiation. The photoimmobilized insulin enhanced the growth of anchorage-dependent cells such as Chinese hamster ovary CHO-K1 and mouse fibroblast STO cells by more than native or azidophenyl-derivatized insulin. A small amount of photoimmobilized insulin (1-10% of the amount of the native or derivatized insulin) enhanced the growth of CHO-K1 and STO cells. In addition, the maximal mitogenic effect of the immobilized insulin was greater than that of native or derivatized insulin. Photoimmobilization could be a universal means of immobilizing growth factors onto the surface of materials devoid of chemical functional groups scaffolding growth factors and providing a new protein-free cell culture system or tissue engineering materials.

Animals↗

PubMedDate not supplied

Capture of rare cells in suspension with antibody-coated polystyrene beads.

A method for the separation of one cell type present in small number from a predominant mixture of cell types using macroscopic polystyrene beads is demonstrated. An antibody specific to murine leukocytes (CD45) was adsorbed to the surface of the beads. Beads and murine hybridoma B cells were placed in test tubes and periodically inverted at fixed time intervals, causing the beads to settle through the suspension under creeping flow conditions. Capture was dependent upon interception: the captured cells must have traveled along streamlines that brought them to within a cell radius of the bead surface. B cells attached to 99-micrometer beads (maximum shear rate 8.1 s-1) were captured with greater efficiency but in lesser quantity than those attached to 170-micrometer beads (maximum shear rate 13.9 s-1). Cell capture unexpectedly reached a plateau in less than 2 h, a phenomenon that appears to involve changes in both the cells and the beads. Capture of cells was effective out to dilutions of 1:10 000 with purity in the captured population of better than 74%. This method allows for the study of physical parameters important for cell attachment and capture as well as for practical separation of rare cells.

Animals↗