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Redistribution reaction of quaternized poly-4-vinylpyridine polycations and their conjugates with alpha-chymotrypsin by oppositely charged latex particles is disclosed. The polycations are strongly adsorbed on the latex surface. Nevertheless, they are able to migrate between the latex species via occasional interparticle contacts. In the case of a homogeneous latex such interchange results in uniform distribution of polycations by latex particles. The distribution drastically changes, when alpha-chymotrypsin-polycation conjugates interact with a mixture of two latexes: one chemically modified by bovine serum albumin and the other one by specific protein inhibitor of alpha-chymotrypsin. In this case the interchanging polycations are finally fixed on the latex particles carrying the centres of specific binding of the enzyme vector, i.e. recognize them in the latex mixture. The obtained results are considered to mimic physico-chemical interaction and recognition of target supermolecular bio-objects by large macromolecules carrying relatively small molecular vectors.
The surface of medical devices is a common site of bacterial and fungal adhesion, first step to the constitution of a resistant biofilm leading frequently to chronic infections. In order to prevent such complications, several physical and chemical modifications of the device surface have been proposed. Here, we experiment a new type of topical antifungal coating using the layer-by-layer technique. The nanometric multilayer film obtained by this technique is functionalized by the insertion of a chromogranin A-derived antifungal peptide (CGA 47-66, chromofungin). We show that the embedded peptide keeps its antifungal activity by interacting with the fungal membrane and penetrating into the cell. In vitro studies demonstrate that such an antifungal coating is able to inhibit the growth of yeast Candida albicans by 65% and completely stop the proliferation of filamentous fungus Neurospora crassa. The cytotoxicity of such a coating was also assessed by growing human gingival fibroblasts at its surface. Finally, the antifungal coating of poly(methylmethacrylate), a widely used material for biomedical devices, is successfully tested in an in vivo oral candidiasis rat model. Taken together, these results assessed the functionalized multilayer films containing a new potent antifungal non-toxic peptide, as a novel and promising technique for local antifungal protection.
The rheological characteristics of the wastewater sludge were investigated by using a Haake Rheostress RS 75 rheometer. The stress-sweep experiments and the small-amplitude-oscillatory-shearing (SAOS) tests were conducted. The stress-sweep measurements demonstrate that addition of polymer coagulants to sludge samples could significantly influence the corresponding complex shear modulus G*. Furthermore, the SAOS tests indicate that the sludge samples treated with polymer coagulants will form more rigid structures. The original sludge samples mostly show typical viscoelastic liquid-like behavior. However, the solid-like behaviors were always observed in the samples treated with polymers.
To investigate the possibility of producing charge-neutral gene delivery complexes with extended, non-particulate structures, DNA was allowed to self-assemble with a series of hydrophilic cationic polymers containing quaternary charged trimethylammonio ethylmethacrylate (TMAEM, 5, 15, 50, 100 mol%) copolymerised with hydrophilic N-(2-hydroxypropyl)methacrylamide (HPMA, 95, 85, 50, 0 mol%, respectively). Copolymers were all able to bind DNA, assessed using ethidium bromide fluorescence, although copolymers with low TMAEM content did not expel ethidium bromide. Increasing TMAEM content of the copolymers changed the morphology of the complexes from extended (5-15 mol% TMAEM), through partially condensed particles (50 mol%) to discrete nanoparticles (100 mol% TMAEM). Complexes based on copolymers with low TMAEM content (5-50 mol%) showed less resistance to degradation by nucleases and lower surface charge (21.2+/-5.9-45.1+/-3.9 mV) than those formed using 100 mol% TMAEM (57.8+/-8.2 mV). They also showed significantly less association with phagocytic cells in vitro (human leucocytes, uptake decreased by up to 92.3%; murine peritoneal macrophages, uptake decreased by up to 69.6%), although in vivo their hepatic accumulation was only slightly decreased (maximum decrease 27.6%). Finding the appropriate balance of hydrophilicity and stability is key to development of effective vectors for gene delivery.
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Hydrolytically degradable, multilayered films ranging from 10 to 100 nm have been constructed by the layer-by-layer deposition of degradable polycations and oppositely charged polyanions. Polycations play dual roles in these systems, serving as structural components of the film as well as transient elements designed to trigger release; polyanions serve as structural components and as entities to be released or delivered. The films erode in a controlled manner under physiological conditions and are suitable for the incorporation and subsequent controlled release of functional polyanions such as DNA.
Our experiments have shown that the joint incubation of thymocytes and syngeneic macrophages in vitro for 60 minutes is accompanied by a certain increase in the helper activity of thymocytes. The presence of polyacrylic acid or the copolymer of acrylic acid and N-vinyl-pyrrolidone, containing 56 mol% of acrylic acid, in this system ensures a considerable increase in the helper activity of thymocytes, incubated jointly with marrow cells and sheep red blood cells and then transferred into a cell culture in vivo.
For the system kappa-carrageenan/amitriptyline it is shown that the degree of binding of amitriptyline is closely related to the carrageenan conformation as regulated by the counterions (Na+ or K+). The adsorption becomes much more pronounced when the carrageenan molecule is in the helix form (counterion K+) than when it has a coil conformation (counterion Na+). Furthermore, for the helical state the adsorption becomes strongly cooperative. It is also shown experimentally that the release from the adsorbed state has a conversion temperature at about 42 degrees C (helix-coil transition). The effect is also related to the linear charge density. For iota-carrageenan with a higher charge density the adsorption is strong and cooperative both in the presence of Na+ and K+ ions.
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The influence on the electrophoretic behavior of polystyrenesulfonates of the percentage of high-molecular-mass chains in an entangled poly(ethylene oxide) solution having a bimodal molecular mass distribution has been investigated and compared with the results obtained for similar solutions of unimodal molecular mass distribution. The comparisons between the different separating polymer solutions were made at a constant total mass concentration, so as to keep constant the mesh size and to highlight the sole effect of the network dynamics. The use of binary polymer mixtures of two different molecular masses but of same nature can be a convenient alternative to modulate the dynamics of the network and the viscosity of the separating medium. A 20-30% content of high-molecular-mass chains in an entangled poly(ethylene oxide) solution having a binary molecular mass distribution appears to be a good compromise for a moderate viscosity and a good separation selectivity in comparison with a solution containing only chains of high molecular mass at the same concentration.
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