Polyelectrolyte complex for imparting antimicrobial properties to a substrate
Inventors
Toreki, William • Moore, David N. • Liesenfeld, Bernd • Mikhaylova, Albina • Olderman, Gerald M.
Assignees
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Publication Number
US-8545862-B2
Publication Date
2013-10-01
Expiration Date
Abstract
Anionic polyelectrolytes are used as binding agents to reduce the solubility of cationic antimicrobial polyelectrolytes. Ionic attraction between the anionic stabilizing polyelectrolytes and the antimicrobial cationic polyelectrolytes results in formation of a polyelectrolyte complex (PEC). A treatment liquid comprising a stable colloid, suspension, dispersion, solution, coacervate, or emulsion of the PEC in an aqueous carrier is used to treat an article, thus coating, infiltrating, or infusing the PEC onto or into the article. Subsequent drying results in an antimicrobial article wherein the PEC is bound to the article and is significantly less prone, relative to either of the component polyelectrolytes, to being washed, leached, leaked, extracted, or migrated from the antimicrobial article during use, or when exposed to aqueous fluids or solvents. The antimicrobial article can be further treated with ethylene oxide which enhances its antimicrobial efficacy, its biocompatibility, and its utility in wound dressings, medical devices, clothing, etc.
Core Innovation
The invention provides an antimicrobial method of preparing an antimicrobial article by using a treatment liquid that consists essentially of a stable aqueous solution, colloid, suspension, dispersion, coacervate, or emulsion of a polyelectrolyte complex (PEC). The PEC is prepared by mixing an aqueous solution of an anionic polyelectrolyte, consisting essentially of a derivative or copolymer of poly(acrylic acid) or polystyrene sulfonate, with a stoichiometric excess of an aqueous solution of an antimicrobial cationic polyelectrolyte, consisting essentially of a quaternary ammonium polymer or a quaternary ammonium copolymer. The anionic and antimicrobial cationic polyelectrolytes are mixed in a controlled manner to produce a PEC that remains evenly dispersed in the treatment liquid, while avoiding significant or non-reversible phase separation, coagulation, or formation of solids, precipitates, flocs, agglomerates, or particles during normal storage or usage.
The anionic polyelectrolyte produces a concentration of 0.025 to 0.20 weight percent in the treatment liquid, and the antimicrobial cationic polyelectrolyte produces a concentration of 0.10 to 0.50 weight percent in the treatment liquid. The molar ratio of charge sites in the antimicrobial cationic polyelectrolyte relative to charge sites in the anionic polyelectrolyte is between 1:1 and 2:1. A treatment liquid meeting these conditions is applied to an article and then dried.
After applying and drying the treated article, the PEC is non-leachably bound to the resulting antimicrobial article. The disclosure presents this drying-based non-leachable binding as reducing wash-off, leaching, and migration relative to the individual components, and reports maintained or greater resistance to leaching after ethylene oxide treatment or sterilization. The disclosure also includes biocompatibility-related considerations using ISO/ASTM cytotoxicity and extractability concepts, including ISO 10993-12 extractability thresholds as part of the overall performance characterization.
Claims Coverage
The partial content includes two independent claims. Both independently require controlled formation of a stable, evenly dispersed polyelectrolyte complex (PEC) using defined anionic and antimicrobial cationic polyelectrolytes, together with constraints preventing significant or non-reversible phase separation and solid formation; the first independent claim further requires applying the treatment liquid and drying to create a non-leachably bound antimicrobial article.
Stable PEC treatment liquid with controlled charge-site mixing
Providing a treatment liquid consisting essentially of a stable aqueous solution, colloid, suspension, dispersion, coacervate, or emulsion of a polyelectrolyte complex (PEC) prepared by mixing an aqueous solution of an anionic polyelectrolyte consisting essentially of a derivative or copolymer of poly(acrylic acid) or polystyrene sulfonate producing a concentration of 0.025 to 0.20 weight percent with a stoichiometric excess of an aqueous solution of an antimicrobial cationic polyelectrolyte consisting essentially of a quaternary ammonium polymer or a quaternary ammonium copolymer producing a concentration of 0.10 to 0.50 weight percent, wherein the molar ratio of charge sites in the antimicrobial cationic polyelectrolyte relative to charge sites in the anionic polyelectrolyte is between 1:1 and 2:1, and wherein the anionic polyelectrolyte and the antimicrobial cationic polyelectrolyte have been mixed in a controlled manner to produce the PEC which remains evenly dispersed in the treatment liquid, and wherein there is no significant or non-reversible phase separation, coagulation, or formation of solids, precipitates, flocs, agglomerates, or particles of the PEC during normal storage or usage of the treatment liquid.
Applying and drying to non-leachably bind PEC antimicrobial article
Applying the treatment liquid to an article, followed by drying the treated article, whereby PEC is non-leachably bound to the resulting antimicrobial article.
Controlled mixing to form stable, evenly dispersed PEC treatment liquid for storage
Mixing, in a controlled manner, an aqueous solution of an anionic polyelectrolyte consisting essentially of a derivative or copolymer of poly(acrylic acid) or polystyrene sulfonate having a concentration of 0.025 to 0.20 weight percent in the treatment liquid, and a stoichiometric excess of an aqueous solution of an antimicrobial cationic polyelectrolyte consisting essentially of a quaternary ammonium polymer or a quaternary ammonium copolymer having a concentration of 0.10 to 0.5 weight percent in the treatment liquid, wherein the molar ratio of charge sites in the antimicrobial cationic polyelectrolyte relative to charge sites in the anionic polyelectrolyte is between 1:1 and 2:1, to produce a treatment liquid consisting essentially of a stable aqueous solution, colloid, suspension, dispersion, coacervate, or emulsion of a polyelectrolyte complex, PEC which remains evenly dispersed in the treatment liquid, and wherein there is no significant or non-reversible phase separation, coagulation, or formation of solids, precipitates, flocs, agglomerates, or particles of the PEC during normal storage or usage of the treatment liquid.
Across the two independent claims, the claim coverage centers on forming a stable, evenly dispersed polyelectrolyte complex (PEC) treatment liquid through controlled mixing of an anionic poly(acrylic acid)/polystyrene sulfonate-derived polyelectrolyte with an antimicrobial quaternary ammonium polyelectrolyte under defined charge-site molar ratio and concentration ranges, while preventing significant or non-reversible phase separation and solid formation. The first independent claim additionally requires applying the PEC treatment liquid to an article and drying so that the PEC becomes non-leachably bound to the resulting antimicrobial article.
Stated Advantages
Non-leachably binding of PEC to the antimicrobial article after drying.
Improved resistance to leaching relative to individual components.
Maintained or greater resistance to leaching after ethylene oxide (EtO) treatment or sterilization.
Biocompatibility and extractability performance as characterized by ISO/ASTM cytotoxicity and ISO 10993-12 extractability concepts (including ppm thresholds).
Antimicrobial efficacy as characterized by log-kill results (including after ethylene oxide treatment/sterilization per the disclosure).
Documented Applications
Treatment of substrates/articles by applying the PEC-containing aqueous treatment liquid followed by drying, including textile-like materials and other substrate types described in the disclosure (e.g., nonwovens, wood pulp, cellulose powder, rayon, cotton gauze).
Antimicrobial performance testing of the resulting antimicrobial articles, including with organisms mentioned in the disclosure and testing frameworks referenced (e.g., ATCC Method 100 and related log-kill characterization).
Sterilization-related use context in which antimicrobial efficacy and resistance to leaching are evaluated after ethylene oxide (EtO) treatment.
Extractability/biocompatibility characterization of the antimicrobial articles, including ISO 10993-12 extractability concepts and cytotoxicity testing frameworks referenced in the disclosure.
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