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PubMed2005

Immune complement activation on polystyrene and silicon dioxide surfaces. Impact of reversible IgG adsorption.

We have studied aspects of the molecular background to immune complement activation on solid surfaces. Quartz crystal microbalance with dissipation monitoring (QCM-D) sensor surfaces were modified by means of spin coating with polystyrene (PS) or sputtering of silicon dioxide (SiO2). The IC activation on modified QCM-D surfaces was investigated by incubation in serum, followed by determinations of the amounts of bound C3 fragments (C3c) at the surface. Determinations of soluble C3a and soluble C5b-9 complex (sC5b-9) were made with enzyme immunoassay (EIA) method. We found that IC activation was high on PS surfaces, independent of the method used for measurements. On the SiO2 surfaces, IC activation was generally lower, but still detectable with anti-C3c as well as sC5b-9 and C3a determinations. Pre-coating the surfaces with a layer of IgG resulted in that IC activation became very high on PS surface, while the IC response remained low on SiO2 surfaces. The lower level of IC activation on the SiO2 surfaces was explained by a low surface concentration of IgG as measured with QCM-D. This was a result of the high reversibility of the IgG protein adsorption as well as absence of sufficient conformational changes of adsorbed IgG molecules. The QCM-D method was as sensitive as the C3a and sC5b-9 determinations to reveal surface associated IC-activation on these model surfaces. Additional advantages of the QCM-D method are the broad dynamic measurement window, i.e. the high precision and the ability to perform time resolved measurements and the ease of making different surface modifications.

Adsorption↗

PubMed2005

Functional assessment of microencapsulated porcine islets with agarose polystyrene sulfonic acid in vitro and in xenotransplantation.

We evaluated the functional efficacy of microencapsulated porcine islet xenografts transplanted into nonobese diabetic (NOD) mice. Islets were isolated from the pancreata of CSK miniature swine by manual collagenase digestion and Ficoll purification. Purified porcine islets were immediately encapsulated into microbeads of agarose polystyrene sulfonic acid (Ag-PSSa). They remained morphologically intact by dithizone staining after 7 days in culture. Insulin secretion from encapsulated islets was determined in response to glucose challenge during perifusion. When encapsulated islets were exposed to 200 mg/dL glucose, within 5 minutes, insulin release became 5-fold greater than that at 80 mg/dL. However, a second phase insulin secretion appeared in response to 250 mg/dL glucose challenge. In xenotransplantation, microencapsulated porcine islets (1000 to 1800 MC islets) were transplanted into the peritoneal cavity of diabetic NOD mice (n = 4) without immunosuppression. The survival times after the onset of diabetes were observed after both MC islets transplanted NOD mice and nontransplanted NOD mice (n = 4). MC islets transplant recipients had significantly (P < .05) longer survival (47.5 +/- 18.6; mean +/- SD) than nontransplanted NOD mice (21.0 +/- 9.31), although random blood glucose levels were not normalized.

Animals↗

PubMed2005

Efficient and selective hydrocarbon oxidation with sodium periodate under ultrasonic irradiation catalyzed by polystyrene-bound Mn (TPyP).

Rapid, efficient and selective alkene epoxidation and alkane hydroxylation with sodium periodate catalyzed by Mn (TPyP) supported on chloromethylated polystyrene, [Mn(TPyP)-CMP], under ultrasonic irradiation were reported. This catalytic system showed high selectivity in epoxidation of stilbenes and R-(+)-limonene and exhibits a particular ability to epoxidize linear alkenes such as 1-heptene. This supported catalyst can catalyze the oxidation of very inert saturated hydrocarbons as well as alkylbenzene derivatives with NaIO4 under ultrasonic irradiation. Under mild reaction conditions, this catalyst was consecutive reused five times without detectable catalyst leaching and gave over 95% epoxide yield in the epoxidation of styrene.

Adsorption↗

PubMed2004

Pyrolysis of virgin and waste polypropylene and its mixtures with waste polyethylene and polystyrene.

A comparison of waste and virgin polypropylene (PP) plastics under slow pyrolysis conditions is presented. Moreover, mixtures of waste PP with wastes of polyethylene (PE) and polystyrene (PS) were pyrolyzed under the same operating conditions. Not only the impact of waste on degradation products but also impacts of the variations in the mixing ratio were investigated. The thermogravimetric weight loss curves and their derivatives of virgin and waste PP showed differences due to the impurities which are dirt and food residues. The liquid yield distribution concerning the aliphatic, mono-aromatic and poly-aromatic compounds varies as the ratio of PP waste increases in the waste plastic mixtures. In addition to this, the alkene/alkane ratio of gas products shows variations depending on the mixing ratio of wastes.

Environmental Pollution↗

PubMed2003

On the colloidal stability of polystyrene particles prepared with surface-active initiators.

The stability of polystyrene latexes prepared with 2,2'-azobis(N-2'-methylpropanoyl-2-amino-alkyl-1)-sulphonates as surface-active initiators (inisurfs) in emulsion polymerization is investigated. The experimentally observed stability during emulsifier-free emulsion polymerization depends on the alkyl chain length of the inisurfs. The calculated barrier height of the overall interaction energy fits nicely with the experimentally observed stability during the polymerization.

Biophysical Phenomena↗

PubMed1991

Size separation of polystyrene sulfate particles (189 to 1085 nm radius) in solutions of methyl-hydroxypropyl-cellulose of different chain lengths.

Polystyrene sulfate particles of 189 to 1,085 nm radius are retarded in their electrophoretic migration in solutions of methyl-hydroxypropyl-cellulose (4,000 and 15,000 cP viscosity for a 2% solution). The retardation is proportional to polymer concentration and increases inversely with particle size. This suggests a separation mechanism based on size-dependent exclusion from the polymer network, as found previously in other liquid polymer media. In the size range of approximately 200 to 600 nm radius, the 4,000 cP polymer exhibits a steeper decrease of retardation with particle size than the 15,000 cP polymer, but fails to exhibit any size dependent retardation beyond that range.

Cholic Acids↗

PubMed1988

Separation of anticardiolipin antibodies from lupus anticoagulant on a phospholipid-coated polystyrene column.

We describe two novel developments. The first is the preparation of a "cemented" chromatography column comprising siliconized sand-coated by and cemented together with polystyrene thus providing a large hydrophobic surface area suitable for passive antigen absorption. The second is the coating of such a matrix with phospholipid and its use for separating anticardiolipin antibodies from lupus anticoagulant activity in the plasma of a patient with the lupus obstetric syndrome. This is the first description of the separate identities of these two antibodies.

Antibodies↗

PubMed1998

Separation of polystyrene microbeads using dielectrophoretic/gravitational field-flow-fractionation.

The characterization of a dielectrophoretic/gravitational field-flow-fractionation (DEP/G-FFF) system using model polystyrene (PS) microbeads is presented. Separations of PS beads of different surface functionalization (COOH and none) and different sizes (6, 10, and 15 microm in diameter) are demonstrated. To investigate the factors influencing separation performance, particle elution times were determined as a function of particle suspension conductivity, fluid flow rate, and applied field frequency and voltage. Experimental data were analyzed using a previously reported theoretical model and good agreement between theory and experiment was found. It was shown that separation of PS beads was based on the differences in their effective dielectric properties. Particles possessing different dielectric properties were positioned at different heights in a fluid-flow profile in a thin chamber by the balance of DEP and gravitational forces, transported at different velocities under the influence of the fluid flow, and thereby separated. To explore hydrodynamic (HD) lift effects, velocities of PS beads were determined as a function of fluid flow rate in the separation chamber when no DEP field was applied. In this case, particle equilibrium height positions were governed solely by the balance of HD lift and gravitational forces. It was concluded that under the experimental conditions reported here, the DEP force was the dominant factor in controlling particle equilibrium height and that HD lift force played little role in DEP/G-FFF operation. Finally, the influence of various experimental parameters on separation performance was discussed for the optimization of DEP/G-FFF.

Electrophoresis↗

PubMed2003

Helical structure of sugar-carrying polystyrene in aqueous solution by circular dichroism.

Radical polymerization of N-p-vinylbenzyl-D-lactonamide (VLA) gave an optically active helical polymer. The stereoregularity of poly(N-p-vinylbenzyl-D-lactonamide) (PVLA) measured by 13C NMR spectroscopy showed a well-resolved sharp-line width, which was assigned to the phenyl C-1 carbon of the isotactic polystyrene (PS). The helical structure of PVLA shown by circular dichroism (CD) indicated that the aromatic groups were chirally supramolecular-packed giving optically active disaccharide units in the side chain covalently linked via an amide linkage with PS, the original PS not being optically active. The intensity of CD for PVLA (a) decreased with increasing temperature due to the change in the conformation of the phenyl group or to the breakdown of intermolecular hydrogen bonding of amide groups and (b) increased in a mixture of water and alcohol due to the increased hydrophobicity. The CD intensity for maltose-carrying PS (PVMA) was slightly higher than that of PVLA CD due to the more hydrophobic property of PVMA than PVLA.

Circular Dichroism↗

PubMed2000

Separation of unmodified polystyrene nanosphere standards by capillary zone electrophoresis.

Size separation of five unmodified polystyrene nanosphere standards with diameters between 50 and 600 nm has been achieved in phosphate buffer solutions as carrier electrolyte. The electrophoretic mobility increases with particle diameter. Optical spectra was shown to be different for particles of different size. Effects of injection time, applied voltage, pH, and phosphate concentration in carrier electrolyte on particle separation were studied. Under optimal conditions the peak efficiency ranged from 600 to 10,500 theoretical plate numbers depending on nanosphere diameter was achieved.

Electrolytes↗

PubMed2001

Influence of the carrier composition on thermal field-flow fractionation for the characterisation of sub-micron polystyrene latex particles.

A study on the influence of the carrier composition in a ThFFF system on the retention and thermal diffusion of sub-micron polystyrene latex particles has been carried out. Various factors that may influence retention were studied. These include: the type of electrolyte and surfactant, their respective concentrations, and the addition of an organic modifier. Particle retention is highly sensitive to small changes in the carrier composition. It is demonstrated that under the conditions applied, secondary effects, such as particle-wall and particle-particle interactions, are negligible. Addition of surfactants is required to minimise particle-wall interactions. Generally, retention increases at higher electrolyte concentration. Furthermore, the addition of acetonitrile (ACN) to an aqueous carrier leads also to an increased retention. The type of surfactant as well as its concentration is of influence on the retention time. The three surfactants that were studied, i.e., sodium dodecyl sulfate, Brij 35 and cetyltrimethylammonium bromide, showed significant differences in particle retention behaviour. The observed differences in retention in the carriers can be attributed to actual changes in thermal diffusion. D(T) appears to be mainly determined by the interaction between the particle's surface and the carrier liquid, and is therefore highly sensitive to changes in the chemical composition of the particle surface and the carrier. Strong differences in size selectivity were found for different carrier compositions. This allows a relatively easy optimisation of the separation. On the other hand, it complicates the size and composition analysis of particles.

Chemical Fractionation↗

PubMed2001

Characterization of polystyrene and polyisoprene by normal-phase temperature gradient interaction chromatography.

Temperature gradient interaction chromatography (TGIC) is applied to the characterization of polyisoprene (PI) and polystyrene (PS) using normal-phase (NP) stationary phase--bare silica or diol bonded silica. Tetrahydrofuran-isooctane mixtures are used as a mobile phase. PI and linear and star shaped PS samples are successfully fractionated in terms of the molecular mass with a high resolution comparable to that of reversed-phase (RP) HPLC. Temperature dependence of the retention shows that the enthalpy of adsorption of PS to the stationary phase is exothermic. In addition, some characteristic features of the NP-TGIC system relative to those of RP-TGIC are presented, which include a high sensitivity on the polar end group and the simultaneous size-exclusion chromatographic and TGIC characterization of PS and PI mixtures.

Butadienes↗

PubMed2001

Ion-exchange properties of hypercrosslinked polystyrene impregnated with methyl orange.

A novel bipolar stationary phase (HCPS-MO) was prepared by impregnation of hypercrosslinked polystyrene (HCPS) with methyl orange (MO; 4-dimethylamino-4'-sulfoazobenzene) and its ion-exchange properties were studied. Simultaneous separation of cations and anions on HCPS-MO is possible, although it behaves preferentially as a cation-exchanger. Unusual selectivity of HCPS-MO for alkali and alkaline-earth metal cations: Na+ < Li+ approximately = K+ < Rb+ < NH4+ < Cs+ and Mg2+ < Sr2+ < Ca2+ < Ba2+ was observed. The effect of temperature on retention of alkali and alkaline-earth metal cations was studied. Separation of Na+, K+, Rb+, NH4+, Cs+, Mg2+ and Ca2+ on HCPS-MO with diluted cerium(III) nitrate solution as an eluent in single run is presented.

Azo Compounds↗

PubMed2001

Selective concentration of gold in water to a polystyrene-embedded fiber disk with polyoxyethylene(10)-p-isononylphenyl ether.

A new surfactant-mediated separation method was developed for concentrating traces of gold ion in water. The methodology is based on the combination of selective complexation of gold(III) with polyoxyethylene(10)-p-isononylphenyl ether, PONPE-10, and strong binding of surfactant complex to hydrophobic polystyrene resins embedded in a PTFE fiber disk (Empore disk). A 400-fold concentration of gold(III) was achieved by 400 ml load of the sample containing 0.01% (w/v) PONPE-10 and 0.10 M nitric acid and by the subsequent elution with 1.0 ml of aqueous buffer solution of 0.01 M N-(dithiocarboxyl)sarcosine diammonium. Traces of gold (0.40 ng/l) in river water samples were successfully determined with inductively coupled plasma MS.

Ethers↗

PubMed1991

Ion-exchange high-performance liquid chromatography of nucleotides and polypeptides on new types of ion-exchange sorbents, based on polystyrene-coated silicas.

A novel type of ion exchanger was prepared by multipoint covalent binding of polystyrene chains onto the surface of porous silica followed by polymer-analogous modification of the bonded layer. Both anion and cation exchangers were synthesized and examined in the separation of nucleotides and proteins. Rapid and efficient separation of basic polypeptides on strong anion exchangers and that of acidic polypeptides on strong cation exchangers could be achieved. For the separation of complete mixtures of polypeptides the application of zwitter-ionic ion exchangers can be recommended.

Animals↗

PubMed1987

High-speed and high-performance size-exclusion chromatography of proteins on a new hydrophilic polystyrene-based resin.

High-performance size-exclusion chromatography of some standard proteins, peptides and amino acids on a new hydrophilic packing material obtained by chemical transformation of a cross-linked polystyrene-divinylbenzene copolymer was studied. Columns filled with 4 and 7 micron particles were compared. The influence of the concentration of acetonitrile, isopropanol and trifluoroacetic acid in the mobile phase on the chromatographic performance was investigated. A good linear calibration graph covering the molecular weight range from 200 to 700,000, was obtained under the optimal conditions. The packing material can be used for separations, for molecular weight determinations and for the pre-fractionation of proteins. The high rigidity of the packing material allows relatively high pressures to be used and therefore fast separations to be achieved. The packing material was applied to the chromatography of proteins from beer, bones and milk.

Acetonitriles↗

PubMed2002

Analysis of mono- and diesters of o-phthalic acid by solid-phase extractions with polystyrene-divinylbenzene-based polymers.

Retention mechanisms of an unmodified and a hydroxylated polystyrene-divinylbenzene polymer were studied by solid-phase extraction of o-phthalic acid and some of its mono- and diesters from purified water and then analysing by GC-MS. The monoesters and phthalic acid were retained only when protonated (i.e. acidified with HCI to pH 0.9). Of all elution solvents tested, ethyl acetate gave the best overall recoveries (61-89%) with both polymers. Applicability to complex matrixes (e.g. acidogenic landfill leachates) was examined by introducing a washing step with acetone in acidified water (pH 0.9) to eliminate volatile fatty acids (C2-C6) from the cartridge. Finally, the method was tested on real samples.

Esters↗

PubMed2002

Surface area determination of a polystyrene-divinylbenzene chromatographic packing material via ionic amphiphile adsorption from aqueous mobile phases and application of Gouy-Chapman theory.

A method for the determination of the chromatographically accessible area of a reversed-phase column similar to the method of Hägglund and Ståhlberg [J. Chromatogr. A 761 (1997) 13] is applied to a column containing a polystyrene-divinylbenzene resin. Its theoretical basis is Gouy-Chapman theory in combination with an electrostatically modified linear adsorption isotherm. The surface area value determined for the resin, 96 m2/g, is much less than the reported surface area value, 400 m2/g, determined by N2 sorptometry and application of Branauer-Emmett-Teller (BET) theory. The method also provides a value for the number of moles of native anionic sites present on the column.

Adsorption↗