scholarly journals Antibacterial activity of chitosan and the interpolyelectrolyte complexes of poly(acrylic acid)-chitosan

2010 ◽  
Vol 53 (3) ◽  
pp. 623-628 ◽  
Author(s):  
Hortensia Ortega-Ortiz ◽  
Baltazar Gutiérrez-Rodríguez ◽  
Gregorio Cadenas-Pliego ◽  
Luis Ibarra Jimenez

The antimicrobial activity of chitosan and water soluble interpolyelectrolyte complexes of poly(acrylic acid)-chitosan was studied. Chitosans of two different molecular weights were tested at different concentration for 0.5 to 5 g·L-1 as antimicrobial agents against P. aeruginosa and P. oleovorans. In both cases, the best microbial inhibition was obtained with the concentration of 5 g·L-1. However, the interpolyelectrolyte complexes of poly(acrylic acid)-chitosan with composition φ =2 produced higher antibacterial activity than the two chitosans at the concentration of 0.5 g·L-1. The NPEC2 complex was more effective than chitosans. This could be attributed to the number of moles of the amino groups of chitosan and the carboxylic acid groups of the interpolyelectrolyte complexes poly(acrylic acid).

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1140
Author(s):  
Silvana Alfei ◽  
Gabriella Piatti ◽  
Debora Caviglia ◽  
Anna Maria Schito

The growing resistance of bacteria to current chemotherapy is a global concern that urgently requires new and effective antimicrobial agents, aimed at curing untreatable infection, reducing unacceptable healthcare costs and human mortality. Cationic polymers, that mimic antimicrobial cationic peptides, represent promising broad-spectrum agents, being less susceptible to develop resistance than low molecular weight antibiotics. We, thus, designed, and herein report, the synthesis and physicochemical characterization of a water-soluble cationic copolymer (P5), obtained by copolymerizing the laboratory-made monomer 4-ammoniumbuthylstyrene hydrochloride with di-methyl-acrylamide as uncharged diluent. The antibacterial activity of P5 was assessed against several multi-drug-resistant clinical isolates of both Gram-positive and Gram-negative species. Except for strains characterized by modifications of the membrane charge, most of the tested isolates were sensible to the new molecule. P5 showed remarkable antibacterial activity against several isolates of genera Enterococcus, Staphylococcus, Pseudomonas, Klebsiella, and against Escherichia coli, Acinetobacter baumannii and Stenotrophomonas maltophilia, displaying a minimum MIC value of 3.15 µM. In time-killing and turbidimetric studies, P5 displayed a rapid non-lytic bactericidal activity. Due to its water-solubility and wide bactericidal spectrum, P5 could represent a promising novel agent capable of overcoming severe infections sustained by bacteria resistant the presently available antibiotics.


2015 ◽  
Vol 60 (2) ◽  
pp. 1561-1564
Author(s):  
E.-H. Lee ◽  
K.-M. Kim ◽  
W.-Y. Maeng ◽  
D.-H. Hur

Abstract After preparing aqueous suspensions from magnetite particles with a poly-acrylic acid, we investigated the effects of several experimental parameters. We characterized the stability of the suspensions using visual inspection, sedimentation, adsorption, and thermal stability of the dispersant. The dispersion stability is affected by the solution pH, the concentrations of magnetite particles, the molecular weight, the concentration of the dispersants, and the temperature. The stability of the suspensions increased as the concentration of the dispersant and the temperature increased. In terms of the molecular weights of the dispersant, the suspensions with dispersant of low-molecular weight (1800) were more stable than those of high-molecular weight (250000) at room temperature. However, at high temperature the suspensions with high-molecular weight showed stability. The adsorption efficiency of the dispersant was very low. The dispersant of high-molecular weight showed a higher thermal integrity than that of low-molecular weight. From this work, we obtained the optimum conditions for stable aqueous suspensions of magnetite particles.


Langmuir ◽  
1998 ◽  
Vol 14 (7) ◽  
pp. 1554-1559 ◽  
Author(s):  
Guochang Wang ◽  
Fred Henselwood ◽  
Guojun Liu

Author(s):  
J.P. Armistead ◽  
R.R. Price ◽  
O.-K. Kim ◽  
L.-S. Choi

Small amounts (less than 30 ppm) of polymer dissolved in solution may significantly reduce the work required to pump fluids through a pipe at a given rate. In other words, the drag of the solution along the pipe walls is reduced. Drag reduction by polymers has been well characterized, however the molecular origin of the phenomena is not fully understood. Polymers that exhibit drag reduction characteristics typically have high molecular weight, have predominantly linear, flexible chains, and have an expanded molecular configuration in solution.Work in this laboratory has focused on the drag reduction behavior of poly(acrylic acid), PAA, in recent years. This polymer is one of the most shear stable water-soluble polymers and due to the ionic groups in the polymer chain its conformation in solution changes with pH and ionic strength. In a recent work, PAA solutions of 18 ppm, pH=8.1, showed an initial drag reduction of over thirty-five percent in rotating disc experiments. Over four minutes of shearing the drag reduction decreased to ten percent. This was surprising because of the known shear stability of PAA. When the sheared solution was left undisturbed for two weeks, it did not recover its drag reduction performance. However, the addition of NaCl to the solution during the shearing immediately restored drag reduction to its initial level. It was hypothesized that the shear flow induced interchain association that was possibly stabilized by hydrogen bonding and that the addition of the NaCl caused dissociation and drag reduction recovery. In additional work, fluorescence probe studies showed that shear flow induced local chain rigidity in the originally flexible polymer chains. In this study, the drag reduction experiments were repeated and the configurations of the sheared and unsheared polymer chains were viewed using electron microscopy.


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