Quaternary Poly Research Articles

Electrical Communication Between Graphite Electrodes and Glucose Oxidase/Redox Polymer Complexes

Abstract Redox polymers can fold along the glycoproteins of glucose oxidase (MW 160,000) at low electrolyte concentrations and thereby penetrate the enzyme. Upon penetration, the distance between the redox centers of the polymer and the FADH2 centers of the reduced enzyme is reduced sufficiently for electrons to be transferred and, therefore, for the mediated electro-oxidation of glucose on conventional electrodes. At high (1M) electrolyte (NaCl) concentrations the redox polymers coil. Such coiling prevents the penetration of the enzyme by the redox polymers. Consequently, electron transfer does not take place and glucose is not electro-oxidized. When an appropriate polycationic redox polymer is covalently bound to the enzyme, the electro-oxidation of glucose occurs even at high electrolyte concentrations. Electron transfer from the enzyme's FADH2 centers to copolymers of poly(N-methyl-4-vinylpyridinium) chloride with either poly(vinylferrocene), E° = 0.25V (SCE), or with poly(4-vinylpyridine) complexes of Os(bpy)2Cl, E° = 0.25V (SCE), or of Os(4,4′-dimethylbpy)2Cl, E° = 0.15V (SCE) is rapid. The polycationic poly(4-vinylpyridine) complex of Os(bpy)2Cl can be covalently bound to glucose oxidase by preparing the terpolymer with 4-aminostyrene, diazotization and reaction of the diazonium cations with tyrosine or tryptophane residues of the enzyme. Glucose electrodes made with the redox polymer modified enzyme are relatively stable and sensitive. Furthermore, simple and fast amperometric glucose electrodes can be made by adsorbing either non-quaternized or quaternized poly(vinylpyridine) complexes of [Os(bipyridine)2Cl]2+ (MW 300,000) on graphite, and adsorbing on these polymer films glucose oxidase. These electrodes do not require diffusing redox mediators or membranes to contain the enzyme and the redox polymer. The redox polymer is shown to electrically “wire” the enzyme's redox centers to the electrode. The glucose response of the electrodes is faster than 1 sec; their current increases linearly with glucose concentration through the 0–10 mM range. At 60 mM glucose, their current density is about 20 μA/cm2.

Physical and Biological Properties of Water Soluble Polyelectrolyte Complexes

Water soluble non-stoichiometric polyelectrolyte complexes have been investigated as potential drug carrier systems for parenteral administra tion. Complexes between the polycationic quaternized poly(vinyl imidazole) (QPVI) and an excess of a higher molecular weight partially sulfonated dextran (pDS) were designed to inherit the biocompatible properties of dextran. Polyelectrolyte complexes with an overall anionic nature prepared from excess poly(methacrylic acid) (PMAA) and low molecular weight quaternary poly amines were also studied. Sedimentation velocity techniques and size exclu sion chromatography showed that complexation was present in all of the systems studied under the appropriate conditions. These studies also indicated that an increasing [polycation]/[polyanion] ratio resulted in a smaller, more compact complex conformation. Platelet aggregation studies showed that toxic aggregatory effects normally induced by the polycations, and to a lesser extent the pDS, were eliminated in vitro when they formed part of a soluble polyelec trolyte complex. In vivo distribution studies in mice using 125I-labelled polyca tion complexed with pDS or PMAA showed accumulation of 40-50% of the ad ministered dose in the liver after 2 hours. The polycation present in these com plexes appears to have been prevented, to some extent, from interacting with negatively-charged biological surfaces, such as platelets in vitro. However this complexation was not sufficient, at least for the macromolecules we have ex amined, to prevent the extensive incidence of unwanted interactions in vivo, lead ing to removal of the polyelectrolyte complexes from the circulation. In conclusion it has been shown that the ionic bonds which hold this type of complex to gether, are not sufliciently strong in vivo to preserve a stable complex structure.

Formation of Bivalent Metal Complexes of Quaternary Pyridine and Poly(4-vinylpyridine) Containing Uracil

Monomeric and polymeric compounds containing uracil group, i.e., 3-[2,4(3H)-pyrimidinedionyl]propylpyridinium bromide (2) and quaternary poly(4-vinylpyridine) containing 2,4(3H)-pyrimidinedione (4), were prepared and their complexation with bivalent metal ions was studied by visible and ESR spectroscopy. The concentrated methanolic solution of monomeric ligand 2 and bivalent metal ions like copper(II), cobalt(II), and zinc(II) gave mixed ligand complexes (5a–c) consisting of two molecules of 2, two molecules of methanol, and one bivalent metal ion. Complexes 5a–c in dilute methanolic solution were unstable and transformed to complexes 6 consisting of four molecules of 2 and one ion of bivalent metal. The uracil group of polymer 4 in methanol did not give a mixed ligand complex like 5 but exclusively formed the complex of type 6. On the other hand, compounds 2 and 4 with tetraamminecopper(II) bromide in water gave mixed ligand complexes composed of two molecules of uracil residue, two molecules of ammonia, and one molecular copper(II) ion.

Mobility of Spin Probes in Quaternized Poly(4-vinylpyridine) Membranes

The mobility of nonionic and anionic spin probes in water-containing quaternized poly(4-vinylpyridine) membranes was investigated by means of an electron spin resonance (ESR) technique. Poly(4-vinylpyridine) was quaternized and crosslinked by dibromoalkane Br(CH2)nBr (n=4, 6, 8, 10), and the effects of the side alkyl chain length were studied. Three spin probes, 2,2,4,4-tetramethyl-1,2,3,4-tetrahydro-γ-carboline-3-oxyl (SPII), 2,2,6,6-tetramethyl-1-piperidinyloxy (SPIV), and sodium 2,2,5,5-tetramethyl-1-pyrrolidinyloxy-3-carboxylate (ASPI), were used. In the temperature region examined, the side methylene chain length had no effect on the mobility of SPII and SPIV, but a little effect for ASPI. This suggests that the ASPI can monitor the mobility of the side alkyl chain. In addition, the effects of water on the mobility of the spin probes were investigated. The mobility of the spin probes was much greater in the membrane containing 30 wt% water than in that containing 3 wt% water, and the polarity around the probes was larger in the former than in the latter membrane. From this, as pointed out in our previous papers on nylon 6/spin probe systems, the effects of water are divided into (1) the effects on the mobilities of the polymer chains and probe molecules, and (2) the effects on the microenvironment around the spin probes.

Flocculation Effect to Kaolin Suspension of Quaternary Poly- (2- or 4-vinylpyridine)

Various quaternary poly- (2- or 4-vinylpyridinium) salts (QP2P or QP4VP) were prepared by the alkylation of poly- (2- or 4-vinyl-pyridine) with various alkyl bromides.Flocculation test for 5% kaolin suspension was carried out to elucidate the effect of the chain length of the alkyl bromides and the degree of quaternization. The influence of pH value and the concentration of kaolin suspension on the flocculation effect were examined.Flocculation ability of the quaternary salts was evaluated by sedimentation rate, sedimentation volume and turbidity.The results obtained are as follows. 1) QP 2 VP or QP 4 VP obtained from the higher alkyl bromides showed high rate of sedimentation. 2) The bulky precipitation was obtained with QP 2 VP or QP 4 VP derived from the higher alkyl bromides. 3) The lower charge density of QP 2 VP was effective for clarity of supernatant, and QP 2 VP or QP 4 VP derived from the higher alkyl bromides showed good properties. 4) The rate of sedimentation or clarity of supernatant decreased rapidly at the pH value of 6 to 7.5. 5) Kaolinconcentration from 2.5 to 10% decreased rapidly the sedimentation rate. 6) QP 2 VP or QP 4 VP was more effective comparing with the commercial f locculants such as SUMI-FLOC, PAS-A, and HIMONIC Neo-600.

The Michaelis–Menten-Type Hydrolysis of an Anionic Phenyl Ester by Partly Quaternized Poly(1-vinyl-2-methylimidazole) and Its Copolymers

The catalytic hydrolysis of 3-nitro-4-acetoxy-benzoic acid was carried out mainly at 30°C, pH 8.0 in 1.0-M aqueous KCl. The polymer catalysts used were prepared by partial quaternization of the homopolymer and copolymers of 1-vinyl-2-methylimidazole with methyl iodide. Michaelis–Men ten kinetics were observed for all the catalysts, reaction constants being Km=3–12 mM and kcat=0.01–0.002 min−1. Both Km and kcat values were maximal when the extent of quaternization of MVI polymer was 5–20%. This was probably attributable to the conformational change of the catalytic site in this region. Otherwise, the catalytic activity was explicable in terms of hydrophobic and electrostatic interactions between catalyst and substrate. In the partly quaternized polymers, the binding capacity and the intracomplex reactivity, in general, were increased or decreased simultaneously by varying the polymer composition. However, the binding and intracomplex reaction were compensatory in the case of uncharged polymer catalysts.

Some Difficulties in Manipulation of the Ribbon Arch Mechanism and Suggestions for their Solution

We report a strategy in improving the diffusion dialysis efficiency of anion exchange membranes (AEMs) by implementing a multi-amine oligomer bridge in the membrane matrix. The multi-amine oligomer, poly-dimethyl aminoethyl methacrylate (PD) was prepared via free radical polymerization, followed by partial quaternization with methyl iodide. The remaining tertiary amine groups were designed to react with benzyl bromide groups in the polymer brominated poly(2,6-dimethyl-1,4-phenylene oxide (BPPO) matrix, thus creating an intermolecular connection. The intermolecular connection serves as crosslinks and also helps to regulate the interconnectivity of the hydrophilic regions. By tuning the molecular weight and the remaining tertiary amine groups within PD, series of AEMs were fabricated. These membranes show potential in recovering waste acid via diffusion dialysis. For example, membrane M-5 shows an extraordinarily high separation factor (SH/Fe) of ∼2074 along with acceptable proton dialysis coefficient (UH=0.0098 m/h). The SH/Fe is much higher than that of the conventional quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (QPPO) membrane without oligomer cross-linker (UH=0.0080–0.0132 m/h, SH/Fe=5–60). The improvement in diffusion dialysis efficiency could be attributed to the improved interconnectivity of the hydrophilic regions, which stems from the incorporation of inter-chain ionic bridge.