Search results for "Polyelectrolyte"
showing 10 items of 214 documents
Aqueous solution chemistry of alkyltin(IV) compounds for speciation studies in biological fluids and natural waters
2012
Abstract Organotin(IV) cations behave as Lewis acids of different strength depending on the charge, according to the following acidity scale: RSn3+ > R2Sn2+ > R3Sn+. For this reason they can react with Lewis bases containing –O, –N, –S donor groups to form complex species of different stability. Complex formation of organotin(IV) moieties with a great number of inorganic and organic ligands in aqueous solution is reviewed here in the light of their environmental and biological impact. To this end, complex species formation was considered in different ionic media and at different ionic strengths, with reference to the composition of natural waters and biological fluids. In particular, the in…
A physiologically active interpenetrating collagen network that supports growth and migration of epidermal keratinocytes: zinc-polyP nanoparticles in…
2020
The distinguished property of the physiological polymer, inorganic polyphosphate (polyP), is to act as a bio-intelligent material which releases stimulus-dependent metabolic energy to accelerate wound healing. This characteristic is based on the bio-imitating feature of polyP to be converted, upon exposure to peptide-containing body fluids, from stable amorphous nanoparticles to a physiologically active and energy-delivering coacervate phase. This property of polyP has been utilized to fabricate a wound mat consisting of compressed collagen supplemented with amorphous polyP particles, formed from the inorganic polyanion with an over-stoichiometric ratio of zinc ions. The proliferation and t…
Proof of multilayer structural organization in self-assembled polycation-polyanion molecular films
1994
Abstract Multilayer organization of ultrathin polycation-polyanion self-assembled films is demonstrated using two approaches. (1) Fabrication of polyion superlattices with alternation of three different polyelectrolytes in (ABCB) n fashion, which gives rise to a Bragg peak in X-ray reflectivity. The spacing d=93.4 A corresponds to the repeat unit (ABCB) n . (2) Drying-induced manipulation of the film surface at regular intervals. Normally the layer-by-layer adsorption is carried out by keeping the film wet throughout all deposition cycles. Alternatively the film surface can be manipulated by gently drying the film in a stream of nitrogen or air after the adsorption of every layer. When the …
Macromolecules in ordered media VIII. High-performance size-exclusion chromatography as a technique for characterizing the interaction between polyan…
1997
Abstract The association of polyanions with liposomes based on dimyristoyl phosphatidyl choline and stearylamine at a ratio of 50:50 was investigated in terms of the binding model and, to a lesser extent, of the partition model. Aqueous size-exclusion chromatography has been proposed as a major technique for monitoring the interactions between liposomes and polyelectrolytes and the results were compared with those obtained by fluorescence spectroscopy. Quantitatively, the extent of the association follows the order: Sodium poly(styrene sulfonate) ( K A = 10 000 M −1 ), poly (acrylic acid) ( K A = 2000 M −1 ) and poly ( l -glutamic acid) ( K A = 700 M −1 ). Also, the effect of the ionic stre…
Macromolecules in ordered media. 6. Effect of the phospholipidic bilayer composition on poly (2-vinyl pyridine) - liposome association
1997
The intrinsic fluorescence emission of poly (2-vinyl pyridine) has been exploited in order to gain insight into the nature of the interaction with artificial membranes. In this contribution, the study has been focused on the effect of the phospholipid bilayer composition on the association to the polymer. Fluorescence data have been converted into association isotherms and then analyzed in terms of both binding and partition models. Results show that the association is enhanced by the presence of negative charged phospholipid as a constituent of the liposomal membrane. The strong surface density dependence of the polymer-liposome association indicatesthe predominantly electrostatic nature o…
Macromolecules in ordered media: 7. Influence of ionic strength and bilayer composition on the association of polyelectrolytes to mixed liposomes
1997
The effect of both the phospholipid composition of the bilayer and the ionic strength of the medium on the association between poly(2-vinyl pyridine) and mixed liposomes based on dimyristoyl phosphatidic acid and dimyristoyl phosphatidil choline was investigated using fluorescence spectroscopy. Intensity changes upon addition of vesicles have allowed us to estimate the extent of the association and data have been processed as association isotherms. We found that the association is enhanced by increasing both the ionic strength and the anionic phospholipid fraction. However, whereas the negative net charge of the bilayer strongly enhances the interaction, the presence of more and more electr…
Mechanistic basis for unexpected bioavailability enhancement of polyelectrolyte complexes incorporating BCS class III drugs and carrageenans
2013
The objective of this study was to investigate the potential of λ-carrageenan to work as an absorption modifying excipient in combination with formulations of BCS class 3 substances. Trospium chloride was used as a model BCS class 3 substance. Polyelectrolyte complexes of trospium and λ-carrageenan were produced by layer-by-layer complexation. A λ-carrageenan-containing formulation was administered either in capsules size 9 to rats by gavage or directly into ligated intestinal loops of rats. Exceptionally strong variations were observed in the plasma concentrations of the rats that received λ-carrageenan compared to the control group, but enhanced plasma concentrations were observed only in…
Selective Inhibition of Human Natural Killing and Antibody-Dependent Cellular Cytotoxicity by a Polyanion
1987
A high molecular polyanion, Liquoid, was found to inhibit at nontoxic concentrations (12-50 micrograms/ml) the natural killing (NK) and the antibody-dependent cellular cytotoxic (ADCC) activity of human peripheral blood mononuclear cells selectively. Whereas NK of the K 562 target cell was slightly or not at all affected, the spontaneous lysis of PDe-B-1, an EBV-transformed B-cell line, was strongly inhibited or even completely abolished. ADCC activity could only be inhibited by Liquoid if the target cells were mycoplasma-free, while the polyanion had no effect when mycoplasma-contaminated target cells were used. Liquoid did not alter the target binding capacity of the NK effector cells and…
Fine-tuning DNA/albumin polyelectrolyte interactions to produce the efficient transfection agent cBSA-147.
2010
We present the preparation and isolation of different chemically modified BSA species with varying numbers of primary amino groups at the surface. Highly cationic albumin proteins with increased numbers of amino groups were achieved and complex formation with plasmid DNA was carefully investigated. We compare the transfection results, polyelectrolyte complexes morphologies with their impact on complex stabilities, cytotoxicities and DNA accessibility. This knowledge-driven approach led to the identification of the efficient non-viral DNA delivery agent cBSA-147, which showed high transfection efficacies and stability.
Preparation of conductive PDDA/(PEDOT:PSS) multilayer thin film: influence of polyelectrolyte solution composition.
2014
Abstract Self-assembled multilayer films made of PEDOT:PSS poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) and PDDA poly(diallyldimethylammonium chloride) were prepared using layer-by-layer method. In order to modify the growth regime of the multilayer, to fabricate an electrical conductive film and to control its thickness, the effects of pH, type of electrolyte, ionic strength and polyelectrolyte concentration were investigated. Optical reflectometry measurements show that the pH of the solutions has no effect on the film growth while the adsorbed amount increases more rapidly when BaCl2 is used instead of NaCl as electrolyte. An increase in the ionic strength (with NaCl) induces…