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Query: UMLS:C0267964 (PAA)
 2,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mixed micelles of cetyltrimethylammonium chloride (CTAC) and n-dodecyl hexaoxyethylene glycol monoether (C12E8) bind to polyanions when the mole fraction of the cationic surfactant exceeds a critical value (Yc). Yc corresponds to a critical micelle surface charge density at which polyelectrolyte will bind to this colloidal particle. Turbidimetric titrations were used to determine Yc for such cationic-nonionic micelles in the presence of acrylic acid and acrylamido-2-methylpropane sulfonate homopolymers (PAA and PAMPS, respectively) and their copolymers with acrylamide, as function of pH, ionic strength, and polyelectrolyte counterion. In 0.20 M NaCl, Yc for PAA is found to be remarkably insensitive to pH, i.e., virtually independent of the apparent polymer charge density xiapp. On the other hand, the expected inverse relationship between Yc and xiapp is observed either for PAA when NaCl is replaced by TMACl (tetramethylammonium chloride), or when xiapp is manipulated using acrylic acid/acrylamide copolymers at high pH. The effective charge density of PAA is thus seen to be suppressed by specific sodium ion binding, indicating that the influence of salts on the interaction of polycarboxylic acids with colloidal particles may differ qualitatively from their effect on the analogous behavior of strong polyanions. Comparisons between homo- and copolymers of acrylic acid were carried out also to test the hypothesis that the "mobility" of charges on PAA at moderate pH (degree of ionization less than unity) could make this "annealed" polymer exhibit the behavior of a more highly charged one. The results, while consistent with this expectation, were obscured by the likely effect of copolymer sequence distributions. Copyright 1998 Academic Press.
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PMID:Binding of Polycarboxylic Acids to Cationic Mixed Micelles: Effects of Polymer Counterion Binding and Polyion Charge Distribution. 973 88

This study investigated the relationship of the washability of gels based on two mucoadhesive polymers (sodium carboxymethylcellulose [NaCMC] and polyacrylic acid [PAA]) and their mixtures to their physical properties such as consistency and hydration/dissolution. The mucoadhesive properties of the two polymers and the effect of mucus-polymer interaction on gel washability at the mucoadhesive interface were also investigated using mixtures of PAA and NaCMC gels with increasing mucin amounts. Release and wash-away properties of the gels were assessed by means of a simultaneous release and wash-away test, whereas the consistency and hydration/dissolution properties of the gels were investigated by rheological analysis (viscosity and dynamic viscoelastic tests) and liquid uptake measurements, respectively. The results showed that PAA was characterized by lower release and wash-away properties than those of NaCMC. Mixing of two gels at different ratios allowed modulation of the release and wash-away properties. A relationship between washability and hydration/dissolution properties was found. Gel consistency by itself did not always provide a complete explanation of the wash-away process. The two polymers investigated showed different rheological interaction properties with mucin. Depending on the extent of such interaction, gel-mucin mixture had hydration/dissolution and washability properties that were quite different with respect to the initial gel.
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PMID:Drug release and washability of mucoadhesive gels based on sodium carboxymethylcellulose and polyacrylic acid. 1002 13

In this paper we show that hyperbranched polymers can be used as a host matrix for electrostatic entrapment of enzymes. Specifically, amine-functionalized glucose oxidase (GOx+) and horseradish peroxidase, as well as poly(amidoamine) dendrimer-modified horseradish peroxidase, reversibly sorb into polyanionic, hyperbranched poly(sodium acrylate) (PAA-) films that are on the order of a few hundred angstroms thick. The quantity of GOx+ entrapped within the PAA- films depends on the nature of film preparation but is typically on the order of 0.06 unit/cm2. The extent to which entrapped GOx+ retains its activity depends on the film history, but for PAA-/GOx+ composites not exposed to glucose and stored at 4 degrees C, the original activity is retained for up to 68 days and perhaps longer.
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PMID:Electrostatic immobilization of glucose oxidase in a weak acid, polyelectrolyte hyperbranched ultrathin film on gold: fabrication, characterization, and enzymatic activity. 1045 Jan 59

The aim of this work was to evaluate how the addition of mucoadhesive polymers to aqueous solutions affects the ocular response of tropicamide (0.2%; w/v). The polymer solutions tested were carboxymethylcellulose sodium salt (CMC-Na; 1%; w/v), hyaluronic acid sodium salt (HA-Na; 0.1%; w/v) and polyacrylic acid (PAA; 0.2%; w/v). Polymeric solutions were compared to a nonviscous formulation (AS). In vitro mucoadhesion measurements were expressed as a percentage of the adhesion force mucin-mucin, considering this one as 100% mucoadhesion. The values ofmucoadhesion obtained were 172%, 127%, 103% and 87.6% for formulations with CMC, PAA, HA and AS, respectively. The mydriatic response of tropicamide was determined in adult male New Zealand rabbits, weighing 1.7-2 Kg, by pupil diameter measurements at different times after instillation. The area under the mydriatic response-time curve (AUC 0-6 hr) was interpreted as an indication of the bioavailability of tropicamide in each vehicle. The AUC 0-6 hr was related to the in vitro mucoadhesion for each formulation. Tropicamide solutions with CMC-Na and PAA resulted in mucoadhesion and AUC 0-6 hr values approximately 1.9 and 1.4 times higher than AS. Although the solution with HA-Na was less mucoadhesive than PAA, the hyaluronic acid solution resulted in a higher AUC mydriasis/time value. Formulations with HA-Na and PAA presented values of surface tension close to that observed in the lacrimal fluid, with the Imax (maximum pupil diameter) being higher than for CMC-Na and AS. Greater than 90% of the mydriatic effect disappeared 4.5 hr after instillation for PAA and AS. Nevertheless, the mydriatic effect remained up to 5.5 hr for HA-Na and CMC-Na. HA-Na solution enhanced the bioavailability oftropicamide, presenting a value of mucoadhesion similar to the reference mucin-mucin.
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PMID:Enhancement of the mydriatic response to tropicamide by bioadhesive polymers. 1111 33

We have developed a new mucoadhesive drug delivery formulation based on an ionic complex of partially neutralized poly(acrylic acid) (PAA) and a highly potent beta blocker drug, levobetaxolol x hydrochloride (LB x HCl), for use in the treatment of glaucoma. PAA was neutralized with sodium hydroxide to varying degrees of neutralization. Aqueous solutions containing concentrations of LB x HCl equivalent to the degree of PAA neutralization were added to the PAA solutions and formed insoluble complexes, which were isolated. The complex formation was followed by turbidimetric titration, and the complexes were characterized by IR and 1H NMR spectroscopy. Complexes were prepared with varying degrees of drug loading, such that the same PAA chain would have free -COOH groups for mucoadhesion along with ionic complexes of LB x H+ with COO- groups. Thin films of the complexes dissociated to release the drug by ion exchange with synthetic tear fluid. The films shrunk continuously during release of the drug and dissolved completely in 1 h. Solid inserts of these films could be useful as a mucoadhesive ophthalmic drug delivery system.
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PMID:Insoluble ionic complexes of polyacrylic acid with a cationic drug for use as a mucoadhesive, ophthalmic drug delivery system. 1126 74

Non-covalent molecular imprinting of poly(allylamine hydrochloride) (PAA HCl) with glucose phosphate mono-sodium salt produced molecularly imprinted polymer (MIP) hydrogels capable of quantitative, isomerically specific binding of glucose. By ionic association of a template molecule, glucose phosphate mono-sodium salt, to the polymer prior to covalent crosslinking, MIP hydrogels were created with an affinity for binding glucose. In this study we have synthesized MIPs using epichlorohydrin, ethylene glucol diglycidyl ether, and glycerol diglycidyl ether as crosslinkers in order to evaluate their effectiveness with respect to molecular imprinting for glucose. MIP hydrogels were also synthesized with the different crosslinkers and varying amounts of the template molecule in an attempt to elucidate the impact of imprint quantities on the effectiveness of the imprinting technique. Batch equilibration studies, using each of the MIPs and similar non-molecularly imprinted polymers were performed to determine their binding capacities with respect to glucose and fructose. The binding capacity data are discussed and employed in the evaluation of the specificity imparted by the imprinting procedure. MIP hydrogels with binding capacities in excess of 0.5 g of glucose per gram of dried gel were synthesized. Isomeric specificity in hydrogels imprinted for glucose was demonstrated by higher binding capacities of glucose than those of fructose in the same polymers.
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PMID:Molecularly imprinted polymer hydrogels displaying isomerically resolved glucose binding. 1137 47

The antimicrobial effects of sodium hypochlorite (SH, 200 ppm, at an adjusted pH of 6.80 +/- 0.20 and at an unadjusted pH of 10.35 +/- 0.25), quaternary ammonium compound (pH 10.20 +/- 0.12, 200 ppm), and peroxyacetic acid (PAA, pH 3.45 +/- 0.20, 150 ppm) on previously acid-adapted or nonadapted Listeria monocytogenes inoculated (10(5) CFU/ml) into beef decontamination water washings were evaluated. The effects of the sanitizers on suspended cells (planktonic or deattached) and on cells attached to stainless steel coupons obtained from inoculated washings stored at 15 degrees C for up to 14 days were studied. Cells were exposed to sanitizers on days 2, 7, and 14. The pathogen had formed a biofilm of 5.3 log CFU/cm2 by day 2 of storage (which was reduced to 4.6 log CFU/cm2 by day 14), while the total microbial populations showed more extensive attachment (6.1 to 6.6 log CFU/cm2). The sanitizers were more effective in reducing populations of cells in suspension than in reducing populations of attached cells. Overall, there were no differences between previously acid-adapted and nonadapted L monocytogenes with regard to sensitivity to sanitizers. The total microbial biofilms were the most sensitive to all of the sanitizers on day 2, but their resistance increased during storage, and they were at their most resistant on day 14. Listeria monocytogenes displayed stronger resistance to the effects of the sanitizers on day 7 than on day 2 but had become sensitized to all sanitizers by day 14. SH at the adjusted pH (6.80) (ASH) was generally more effective in reducing bacterial populations than was SH at the unadjusted pH. PAA generally killed attached cells faster at 30 to 300 s of exposure than did the other sanitizers, except for ASH on day 2. PAA was more effective in killing attached cells than in killing cells treated in suspension, in contrast to the other sanitizers.
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PMID:Biofilm formation by acid-adapted and nonadapted Listeria monocytogenes in fresh beef decontamination washings and its subsequent inactivation with sanitizers. 1243 Jun 92

Polyionic complexes of chitosan (CS) and poly(acrylic acid) (PAA) were prepared in a wide range of copolymer composition and with two kind of drugs. Release of amoxicillin trihydrate and amoxicillin sodium from these different complexes were studied. The swelling behavior of and solute transport in swellable hydrogels were investigated to check the effect of polymer/polymer and polymer/drugs interactions. The electrostatic polymer/polymer interactions take place between the cationic groups from CS and the anionic ones from PAA. The diffusion of amoxicillin trihydrate was controlled only by the swelling/eroding ratio of the polyionic complexes. The swelling degree of amoxicillin sodium hydrogels was more extensive when compared to the swelling degree of amoxicillin trihydrate formulations. It was concluded that the water uptake was mainly governed by the degree of ionization. Restriction of amoxicillin sodium diffusion could be achieved by polymer/ionized-drug interaction that retards the drug release. Freeze-dried polyionic complexes could serve as suitable candidates for amoxicillin site-specific delivery in the stomach.
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PMID:Release of amoxicillin from polyionic complexes of chitosan and poly(acrylic acid). Study of polymer/polymer and polymer/drug interactions within the network structure. 1252 91

The bacterial surfaces of enterococci are not uniform. This fact is confirmed by several studies and by our results when great differences between individual strains with regard to their cell surface hydrophobicity, binding of eight ECM (extracellular matrix) molecules immobilized on latex beads and four selected ECM molecules in microtiter plates were observed. The strains expressing high binding of ECM molecules (e.g., HJ 18, HJ 23, HJ 24, HJ 26, HJ 28, HJ 36, etc.) were found among Enterococcus faecalis and E. faecium by PAA (particle agglutination assay). On the other hand, weak ECM binders (e.g., HJ 21, HJ 32, HJ 34, HJ 38, HJ 39, HJ 42, HJ 43) were also found. A direct correlation was found between porcine mucin and fetuin binding ability of eight selected strains tested in microtiter plates and by PAA. Moreover, the influence of tunicamycin treatment was different because significant (P < 0.001) blocking effect of tunicamycin was observed with two selected strains (HJ 26 and HJ 36), whereas two strains (HJ 18 and HJ 22) were not significantly affected in their fetuin binding. The treatment of six enterococcal strains with proteolytic enzymes, pronase P, and trypsin, and with sodium metaperiodate also significantly (P < 0.001) decreased their fetuin binding. This suggests that both protein and carbohydrate moieties are involved in the binding of immobilized fetuin. However, the influence of these chemicals on the fetuin binding by individual strains was different.
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PMID:Binding of extracellular matrix molecules by enterococci. 1273 51

Experiments measuring the solubility of kaolin particles in terms of the concentration of aluminum and silicon ions in supernatant were carried out as a function of the pH of the slurry over a wide range of dosages of different dispersing agents varying from 0.5 to 12 mg/(g solids). The concentrations of the metal ions in supernatant were found to be strongly affected by the type and the dosage of the dispersants and pH of the solution. In this study, the mechanism of the reaction between the dispersing agents and kaolin particles was studied and the dissolution capacities of metal ions (aluminum and silicon) were identified from kaolin particles in the absence and presence of dispersing agents. The three anionic dispersing agents used were sodium polyacrylate (Na-PAA), sodium hexametaphosphate (Na-HMP), and sodium silicate (Na-silicate), based on the industrial application of these agents and their ability to produce a stable dispersion for this purpose.
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PMID:Influence of dispersing agents and solution conditions on the solubility of crude kaolin. 1475 85


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