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PubMedDate not supplied

Surface modification of polycarbonate with synthetic polyelectrolyte-anticoagulant activity.

Natural rubber with C = C bonds had been modified by reaction with chlorosulfonyl isocyanate (CSI) and 70% of the products were obtained, which yielded polyelectrolyte on treatment with NaOH, having sulfamate and carboxylate groups. The polyelectrolyte showed anticoagulant activity. This might be due to the presence of both sulfamate and carboxylate groups arranged in a steric manner in the molecule as that of Heparin. Surface energy parameters, platelet adhesion and plasma recalcification time were investigated. Possible comparison with heparin had been demonstrated.

Anticoagulants↗
PubMedDate not supplied

Role of reperfusion with polyelectrolyte solution and BN 52021 in hemorrhagic shock-induced changes in rat lungs.

The aim of this study was to test whether reperfusion with isotonic standard polyelectrolyte solution alone has any influence on the redox balance in the lung during hemorrhagic shock, and whether reperfusion and BN 52021, used together have better protective effect on free radical lung injury. The results showed that reperfusion with electrolyte solution increased solely glutathione reductase activity (GSSG-R), and diminished the activities of Cu,Zn-superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) as well as the content of SH-groups. Thiobarbituric acid reactive substances (TBA-rs) were much more increased in comparison to hemorrhagic shock. After reperfusion with polyelectrolyte solution and the administration of BN 52021, the antioxidant parameters returned to normal values, while TBA-rs slightly decreased.

Animals↗
PubMed1975

Biological ion exchanger resins. VII. Counter-ion activity coefficients in solutions of biological polyelectrolytes.

The single ion activity coefficients of K+ and Cl- counter-ions were determined in concentrated polyelectrolyte solutions. The polyelectrolytes investigated included DNA and several proteins. Results indicate that ion gradients of up to 40:1 do not lower the counter-ion activity coefficient below 0.5. Thus, published values of the intracellular activity coefficient of K+ are not incompatible with cellular models utilizing cytoplasmic ion exchange.

Binding Sites↗
PubMed2001

Removal of colour and turbidity in pulp and paper mill effluents using polyelectrolytes.

The present study was undertaken for removal of the colour, turbidity and COD from pulp and paper mill effluents using polyelectrolytes for pollution control and its safe disposal. Based on the pH of effluent and nature of colour imparting substance, suitable polyelectrolytes have been selected and used. A novel method of treating the above effluent with 0.2 ml/L of Rishlyte 80 L for the removal of colour, turbidity and COD has been found to be optimal and techno-economically viable when compared with the conventional method of treatment with alum.

Color↗
PubMed1991

Protective action of polyelectrolytes on endothelium.

These results show that heparin and dextran sulfate protect endothelial cells from oxygen-free radicals. Heparan sulfate and dermatan sulfate showed mild protection when measuring cell viability but none when examining the presence of LDH in media. These GAGs are obviously not as effective as heparin and dextran sulfate in protecting endothelial cells from free radical injury. It is possible, however, that other preparations of heparan sulfate and dermatan sulfate may be more effective. In cells that were pretreated with heparin for 24 hours, the protective action occurred immediately after the addition of X/XO. We can conclude that changes observed in cell viability with heparin treatment were not due to stimulation of cell growth, since this occurred too rapidly. As well, we did not observe a significant difference in cell number in cultures treated with polyelectrolytes. These results show that the anionic polyelectrolytes, in particular heparin and dextran sulfate, may be important for the treatment of ischemic episodes and inflammatory associated conditions. As well, this provides support for the argument that heparin and similar drugs are important for the prevention and treatment of atheroma. It is also possible that the presence of heparin in the mast cell may be to prevent surrounding cells from inflammatory injury.

Animals↗
PubMed1990

Grafting of synthetic polyelectrolyte onto polymer surfaces--comparison of glow discharge and 60Co-gamma-irradiation method.

Water soluble polyelectrolyte synthesised from natural rubber contains sulfamate and carboxylate groups similar to that of heparin. It is observed that synthetic heparinoid polyelectrolyte is capable of inhibiting blood coagulation. In the present study, we attempted to graft the same onto polystyrene and polymethylmethacrylate surfaces using glow discharge technique and 60Co-gamma-irradiation method, and the surfaces were compared with respect to water contact angle and platelet adhesion parameters. Heparinised surfaces are also evaluated for relative comparison.

Animals↗
PubMed1985

[Relation of the immunogenicity of artificial antigens to the number of polyelectrolyte-bound protein molecules].

Complexes and covalent conjugates of protein antigens with polyelectrolytes of different molecular mass have been synthesised. The structure and composition of the resulting water-soluble complex particles were determined. Artificial antigen immunogenicity was shown to depend on the amount of protein molecules complexed with polyelectrolytes. Direct correlation between immunostimulating activity of the polymer-carrier, immunogenicity of complex antigens and size-dependent capacity of the polymer molecule to aggregate protein globules has been established.

Acrylic Resins↗
PubMed1980

[Relationship between catalytic properties, fixed charge concentration and electrostatic potential of polyelectrolyte-bound enzymes].

An equation for the calculation of the electrostatic potentials of polyelectrolyte-enzyme supports from electrostatic parameters has been derived by relating two different theories which describe the catalytic behaviour of polyelectrolyte-bound enzymes. The electrostatic potentials of polyionic supports have been determined by use of experimental results, on the one hand, from the fixed charge concentration and the ionic strength, on the other hand, from pH- and Km-shifts of immobilized enzymes. The accordance of potentials calculated from electrostatic and kinetic parameters confirms the macroscopic carrier-enzyme model.

Amylases↗
PubMed1984

Plasma contact activation and decrease of factor V activity on negatively-charged polyelectrolytes.

The effect of negatively-charged polymers, used in some artificial devices, on plasma clotting and kinin systems was studied in vitro using polyelectrolyte complexes. Contact activation was observed as an immediate, transient and surface-dependent phenomenon. After incubation of the plasma with the polymer a small decrease of factor XII activity was noticed, which corresponded to a greater reduction of prekallikrein activity and to a marked kinin release. No significant decrease of factor XII, prekallikrein, HMW kininogen could be detected immunologically. Only the initial contact of the plasma with the polyelectrolyte lead to activation, subsequently the surface became inert. Beside contact activation, factor V activity also decreased in the plasma. The decrease was surface and time-dependent. It was independent of contact factor activation, and appeared to be related to the sulfonated groups of the polymer. If purified factor V was used instead of plasma factor V, inactivation was immediate and not time-dependent suggesting a direct adsorption on the surface. A second incubation of the plasma-contacted polymer with fresh plasma resulted in a further loss of Factor V activity.

Electrolytes↗
PubMed1981

[Polyclonal activation of B-lymphocytes by synthetic polyelectrolytes].

A study was made of the ability of polyacrylic acid, poly-4-vinylpyridine, and the copolymers 4-vinylpyridine and 4-vinyl-N-alkylpyridinium bromides with side hydrocarbonic radicals of varying length to induce in mice of different strains B-cell differentiation into the plaque-forming cells without antigenic stimulation. The polyelectrolytes have been shown to favour the transformation of B lymphocytes to the cells that secrete polyclonal antibodies, i.e. to be polyclonal activators of B lymphocytes. B lymphocyte differentiation induced by the polyelectrolytes does not depend on T cells and is liable to genetic restriction.

Acrylic Resins↗
PubMed1996

Atomic force microscopic analysis of the influence of the molecular weight of poly(L)lysine on the size of polyelectrolyte complexes formed with DNA.

We are developing self-assembling micellar vehicles based on multifunctional block copolymers as well-defined synthetic vehicles suitable for safe in vivo delivery of DNA. As a first stage, DNA expression vectors (6 kb) were condensed with poly(L)lysine of different molecular weights (3970-224 500) to form polyelectrolyte complexes and analysed by atomic force microscopy (AFM). Discrete complexes were formed in every case, although the highest molecular weight poly(L)lysine preparation (224 500) produced large complexes with significant polydispersity (diameters ranging from 120-300 nm), while the smallest poly(L)lysine (3970) produced more homogeneous complexes with diameters ranging from 20-30 nm. Poly (L)lysine preparations of molecular weight 53 700 and 23 800 produced complexes of intermediate size and poly-dispersity. The mean volumes of the complexes formed using poly(L)lysine 224 500 and 3970 were 606 000 nm3 and 3700 nm3, respectively. Polyelectrolyte complexes formed using low molecular weight poly(L)lysine also showed significantly decreased cytotoxicity. Given restrictions of access to many cellular targets and the need for good biocompatibility, synthetic vectors based on DNA condensed with low molecular weight polycations may be more appropriately developed for general use.

Cell Survival↗
PubMed1997

Sequence specificity, enantiospecificity and polyelectrolyte effect in the binding to DNA of a 6-(2-pyridyl)phenanthridine chiral photonuclease.

In order to establish the basis for the rational design of a novel family of intercalating chiral photonuclease drugs aimed at photochemotherapy, namely N, N'-dialkylated 6-(2-pyridinium)phenanthridinium (pyp) dications, a detailed investigation of the DNA binding of the dq2pyp member (where dq2 stands for -CH2CH2-), was conducted. The study addresses the sequence- and enantiospecificity, as well as polyelectrolyte effects in the drug-DNA interaction. Binding isotherms with synthetic polynucleotides, forcefield calculations, affinity chromatography in a DNA-cellulose stationary phase and salt-dependent equilibrium and kinetic studies with DNA were used. dq2pyp shows a strong preference for alternating GC over AT base pairs; binding to homopolymeric DNA is weak (< 3 x 10(4) M-1). Affinity chromatography shows enantiospecific binding of dq2pyp to DNA. The polyelectrolyte contribution to the binding free energy are shown to be relatively important (-4.8 kcal/nmol out of an overall value of -7.2 kcal/mmol at 10.2 mM Na+). The slope of the logkd (dissociation rate constant) vs. log[Na+] plot (0.7) agrees with the values predicted from counterion condensation theory for a dicationic intercalator, giving further support to such a DNA binding mode for dq2pyp. The relatively high kinetic dissociation constants (logkd = 0.70log[Na+] + 3.79) in comparison with those of propidium (two orders of magnitude larger at any Na+ concentration) seems to originate from the absence of amino groups in dq2pyp. The kinetic association constants (logka = -1.06log[Na+] + 5.53) are twice these of propidium, probably due to the less restrictive positioning of dq2pyp at the intercalation site. The kinetic studies support a mechanism of intercalation in which the drug forms a pre-equilibrium outside the complex followed by the intercalation of the drug. Molecular modelling is used throughout to rationalize all the experimental data, as well as to propose new candidates with improved DNA affinity and residence time.

Base Sequence↗
PubMed1997

New anionic polyelectrolyte hydrogel for corneal surgery.

A new high-water-content (78%) anionic polyelectrolyte hydrogel was obtained by phase inversion (demixion) of a polymer solution containing 9.0% poly(acrylonitrile sodium methallylsulphonate), 85.0% dimethylformamide, and 6.0% saline solution (0.9% NaCl). The hydrogel is permeable to water, saline, urea, creatinine, glucose, human albumin, and saline-dissolved oxygen. Investigation of the interactions between human serum and surfaces prepared with the new yielded hydrogel, compared to serum interaction with silica-free silicone (RTV), regenerated cellulose (Cuprophan), MMA/PVP copolymer (Lidofilcon), PMMA (Perspex), FIFE (Gore-Tex), and poly(acrylonitrile sodium methallylsulphonate) hemodialysis membrane (AN-69), showed the hydrogel and hemodialysis membrane (both prepared with AN-69 copolymer) to be the only materials devoid of complement (C')-activating ability.

Biocompatible Materials↗
PubMed2005

The response of normal human osteoblasts to anionic polysaccharide polyelectrolyte complexes.

Polyelectrolyte complexes (PEC) were prepared from chitosan as the polycation and several synthesized functional anion polysaccharides, and their effects on cell attachment, morphology, proliferation and differentiation were estimated using normal human osteoblasts (NHOst). After a 1-week incubation, PEC made from polysaccharides having carboxyl groups as polyanions showed low viability of NHOst on it although the NHOst on it showed an enhancement in their differentiation level. On the other hand, NHOst on PEC made from sulfated or phosphated polysaccharides showed similar attachment and morphology to those on the collagen-coated dish. When the number of NHOst was estimated after 1 week, the number on the PEC was ranged from 70% to 130% of those on the collagen-coated dish, indicating few effects of these PEC on cell proliferation. In addition, NHOst on PEC films made from sulfated polysaccharides differentiated to a level very similar to that observed on the collagen-coated dish, indicating that these PEC films maintain the normal potential of NHOst to both proliferate and differentiate. Measurement of gap junctional intercellular communication of NHOst on PEC revealed that PEC did not inhibit communication, suggesting that PEC films have few effects on cell homeostasis. Thus, PEC made from the sulfated polysaccharide may be a useful material as a new scaffold for bone regeneration.

Alkaline Phosphatase↗
PubMed2005

pH- and temperature-sensitive release behaviors from polyelectrolyte complex films composed of chitosan and PAOMA copolymer.

This paper describes the pH and temperature effects on drug release from polyelectrolyte complex (PEC) films composed of a cationic polymer, chitosan, and an anionic polymer, polyalkyleneoxide-maleic acid copolymer (PAOMA). In this study, we prepared and investigated PEC films in terms of the drug release properties as pH- and temperature-sensitive drug carriers. Drug release rates were tested at pH 3.8 and 7.2, and at 25 and 50 degrees C. Salicylic acid and phenol were selected as model drugs. An increase in pH from 3.8 to 7.2 resulted in an increase in the rate of drug release because of the repulsive forces between carboxyl groups in PAOMA and anionic groups in model drugs. When the hydrophobic PAOMA was used as a polyanion, the drug release rate increased at 50 degrees C. This is attributed to the increase of release area due to the phase transition of PAOMA and the increase of repulsive forces between carboxyl groups in PAOMA and anionic groups in model drugs.

Chitosan↗
PubMed1995

Evaluation of the counterion condensation theory of polyelectrolytes.

We compare free energies of counterion distributions in polyelectrolyte solutions predicted from the cylindrical Poisson-Boltzmann (PB) model and from the counterion condensation theories of Manning: CC1 (Manning, 1969a, b), which assumes an infinitely thin region of condensed counterions, and CC2 (Manning, 1977), which assumes a region of finite thickness. We consider rods of finite radius with the linear charge density of B-DNA in 1-1 valent and 2-2 valent salt solutions. We find that under all conditions considered here the free energy of the CC1 and the CC2 models is higher than that of the PB model. We argue that counterion condensation theory imposes nonphysical constraints and is, therefore, a poorer approximation to the underlying physics based on continuum dielectrics, point-charge small ions, Poisson electrostatics, and Boltzmann distributions. The errors in counterion condensation theory diminish with increasing distance from, or radius of, the polyion.

Biophysical Phenomena↗
PubMed1998

Conjugates of monoclonal antibodies with polyelectrolyte complexes-- an attempt to make an artificial chaperone.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from rabbit muscle is a tetrameric enzyme. Inactivation of GAPDH at 50 degreesC or in the presence of 4 M urea proceeds via formation of inactive dimers followed by their aggregation. Antibodies (clone 6C5) were selected which bind specifically inactive dimers but not native tetramers. The simplified model of chaperone action when the inactive misfolded forms are removed from the reaction media preventing aggregation was developed using antibodies in combination with polyelectrolyte complexes. The antibodies were coupled covalently to polyanionic component of the complex, poly(methacrylic) acid. The treatment of inactivated GAPDH with this conjugate followed by its precipitation after equimolar addition of polycation, poly-(N-ethyl-4-vinylpyridinium) bromide, resulted in a significant increase in the specific activity of GAPDH. The restoration of specific activity was more complete in the experiments with lower GAPDH concentration and in the samples with lower inactivation degree, conditions where aggregation is less pronounced. Some aggregates are formed at high inactivation degree and high GAPDH concentration and observed as an increase in the solution turbidity. They could be removed by centrifugation. Antibody/polyelectrolyte complex treatment followed by centrifugation to remove insoluble aggregates resulted in nearly complete restoration of enzyme specific activity.

Animals↗
PubMed2001

Selective permeation of hydrogen peroxide through polyelectrolyte multilayer films and its use for amperometric biosensors.

A platinum electrode was coated with polyelectrolyte multilayer (PEM) films to prepare an amperometric hydrogen peroxide sensor which can be used in the presence of possible interferences such as ascorbic acid, uric acid, and acetaminophen. The PEM films were prepared on the surface of a Pt disk electrode by an alternate deposition of polycation and polyanion from the aqueous solutions through electrostatic force of attraction. The Pt electrodes coated with a poly(allylamine)/poly(vinyl sulfate) or poly(allylamine)/poly(styrenesulfonate) film were used successfully for detecting H2O2 selectively in the presence of the possible interfering agents. It was suggested that H2O2 can diffuse into the PEM film smoothly while the ascorbic acid, uric acid, and acetaminophen cannot penetrate the film by a size exclusion mechanism. On the other hand, the electrodes coated with PEM films containing poly(ethyleneimine) or poly(diallyldimethylammonium chloride) were not useful for the selective determination of H2O2. The results were rationalized based on the different permeability of the films due to the different molecular density or packing in the PEM films. The PEM film-coated electrode was useful for constructing glucose biosensors by coupling with glucose oxidase.

Acetaminophen↗