Anticoagulant activity of a synthetic heparinoid in relation to molecular weight and N-sulfate content

Addition of chlorosulfonyl isocyanate to C=C bonds in cis-1,4-polyisoprene and reaction of the adduct with NaOH resulted in the formation of a water-soluble polyelectrolyte with N-sulfate and carboxylate groups. The polyelectrolyte showed anticoagulant activity and it was found, just as with heparin, that the activity was related to molecular weight and N-sulfate content

Iron(III)-chelating resins X. Iron detoxification of human plasma with iron(III)-chelating resins

Iron detoxification of human blood plasma was studied with resins containing desferrioxamine B (DFO) or 3-hydroxy-2-methyl-4(1H)-pyridinone (HMP) as iron(III)-chelating groups. The behaviour of four resins was investigated: DFO-Sepharose, HMP-Sepharose and crosslinked copolymers of 1-(ß-acrylamidoethyl)-3-hydroxy-2-methyl-4(1H)-pyridinone (AHMP) with 2-hydroxyethyl methacrylate (HEMA) and of AHMP with N,N-dimethylacrylamide (DMAA). The efficiency of iron detoxification of plasma of the resins was mainly dependent on the affinity of the ligands and the hydrophilicity of the resins. The results of a stability study in phosphate-buffered saline at a physiological pH indicated that AHMP-DMAA was the most stable resin, whereas the Sepharose gels had a relatively lower stability. Experiments with the AHMP-DMAA resin showed that the resin was able to remove iron from plasma with different iron contents, and from plasma poisoned with FeCl3, iron(III) citrate or transferrin. A rapid removal from free serum iron was observed, whereas iron from transferrin was removed slowly afterwards. Only the overload iron was removed since in all cases the normal serum iron level of ca. 1 ppm was obtained

Investigations on vinylene carbonate. V. Immobilization of alkaline phosphatase onto LDPE films cografted with vinylene carbonate and N-vinyl-N-methylacetamide

Low-density polyethylene (LDPE) films cografted with vinylene carbonate (VCA) and N-vinyl-N-methylacetamide (VIMA) were studied as a matrix for the immobilization of the enzyme alkaline phosphatase (ALP) either by direct fixation or by inserting spacers. When water-soluble alkyldiamines such as diaminoethylene, diaminobutane, diethylenetriamine, and diaminohexane were used as spacers between the matrix and the enzyme, the surface concentration (SC) of the active ALP coupled on the matrix was increased, whereas the effect of the spacer on the SC was dependent on the length of the spacer. Bovine serum albumin (BSA) was preimmobilized onto the LDPE films to provide a better simulation of the biological environment for the enzyme, and the SC of ALP on the matrix was significantly increased by coupling ALP onto the BSA preimmobilized surfaces. Compared to native ALP, some physicochemical properties of ALP could be improved by the covalent immobilization

Iron(III) chelating resins-IV. Crosslinked copolymer beads of 1-(B-acrylamidoethyl)-3-hydroxy-2-methyl-4(1H)-pyridinone (AHMP) with 2-hydroxyethyl methacrylate (HEMA)

Iron(III) chelating beads have been synthesized by copolymerization of 1-(ß-acrylamidoethyl)-3-hydroxy-2-methyl-4(IH)-pyridinone (AHMP) with 2-hydroxyethyl methacrylate (HEMA), and ethyleneglycol dimethacrylate (EGDMA) as the crosslinking agent. The synthesis of the AHMP-HEMA beads was performed by suspension polymerization of AHMP, HEMA and EGDMA in benzyl alchol¿20% aqueous NaCl solution using 2,2¿-azobisisobutyronitrile (AIBN) as the initiator and polyvinylalcohol (40¿88) as a suspending agent.\ud \ud The crosslinked copolymer beads were characterized by IR, and the AHMP content was determined by elemental analysis. The AHMP-HEMA beads were not too hydrophilic, and the copolymers absorbed at equilibrium only 40¿50% water. It was found that the copolymer beads were very stable at 25°, but some degradation was observed at 121°.\ud \ud The AHMP-HEMA copolymers were able to chelate iron(III) and the chelation was dependent on the conditions such as pH and temperature. However, the capacities towards iron(III) chelation were always found to be much lower than the calculated values. The influence of the polymeric matrix on the iron(III) chelating ability was studied with iron(III) chelating resins containing various polymeric matrices. It was found that the iron(III) chelating efficiencies of the resins were strongly affected by their hydrophilicities. The low chelating efficiency of the AHMP-HEMA beads (0¿40%) is probably due to their poor swelling in water

Synthetic heparinoids labelled with 125I and 35S

The labelling of a water-soluble synthetic polyelectrolyte, having anticoagulant activity, has been studied. The polyelectrolyte is derived from cis-1,4-polyisoprene and contains N-sulfate and carboxylate groups. [125I]-Iodination of the polyelectrolyte, using the Chloramine-T method and an electrolytic method, resulted in a [125I]-labelled polyelectrolyte from which release of the label occurred. Resulfation of a partially desulfated polyelectrolyte with a [35S]-sulfur trioxide trimethylamine complex resulted in a [35S]-labelled polyelectrolyte which showed no release of the label

Mechanical properties and chemical stability of pivalolactone-based poly(ether ester)s

The processing, mechanical and chemical properties of poly(ether ester)s, prepared from pivalolactone (PVL), 1,4-butanediol (4G) and dimethyl terephthalate (DMT), were studied. The poly(ether ester)s could easily be processed by injection moulding, owing to their favourable rheological and thermal properties. The tensile response of a poly(ether ester) with a butylene terephthalate (4GT) content of 72 mol%, which exhibited the phenomena of necking and strain-hardening, was related to the morphology of these copolymers. The influence of the short 4G-PVL segments was reflected in a high Young's modulus and yield stress, and resulted in a tough behaviour for the poly(ether ester), with an ultimate elongation of 500%. The poly(ether ester)s were stable towards treatment at room temperature with water or weakly acidic or alkaline solutions. Conditioning at 90°C in water for 264 h resulted in a water uptake of 1 wt%, whereas the rate of hydrolysis was 0.0003 (expressed in An rel h-1) for the poly(ether ester) with a 4GT content of 72 mol%. Although a decay in the mechanical properties for the PVL-based poly(ether ester) after exposure to water at 90°C was observed, these materials were assumed to have a higher hydrolytical stability than other poly(ether ester)

Investigations on vinylene carbonate. IV. Radiation induced graft copolymerization of vinylene carbonate and N-vinyl-N-methylacetamide onto polyethylene films

Graft copolymerization of binary mixtures of vinylene carbonate (VCA) and N-vinyl-N-methylacetamide (VIMA) onto low density polyethylene (LDPE) films was studied by the mutual γ-irradiation technique. Sufficient amounts of functionally active VCA groups could be grafted onto the surface and the hydrophilicity of the surface was also improved. The grafting of VCA onto polyethylene films in the binary solutions was found to be promoted by the presence of VIMA, thus showing a positive synergism. The VCA content in the graft copolymers was always higher than in the copolymers obtained by homogeneous copolymerization using the same monomer feed composition. The monomer reactivity ratios, as well as a preferential partitioning of the monomers surrounding the polymeric substrate, were considered to explain the grafting reactions in the binary systems