Communications of the ACM, Vol. Larry Press, Grey Burkhart, Will Foster, Seymour Goodman, Peter Wolcott, and Jon Woodard Over the years, we covered the globe with cities then linked them with railroads, highways, telephone lines, power grids, canals, and so forth. We are now deploying the Internet, and several organizations and projects are tracking this global diffusion . This article describes one such project, the Mosaic Group http:
These include antibiotics such as but not limited to rifampin, gentamicin, vancomycin, neomycin, soframycin, bacitracin, polymycin, synthetic antibiotics including ofloxacin, levofloxacin and ciprofloxacin, antibacterials including biguanides such as chlorhexidine and their salts, alkyl ammonium halides such as benzalkonium chloride cetrimide, domiphen bromide and phenolics such as triclosan.
The antimicrobial coating formulation of the present invention comprise coating solutions that include at least one hydrophilic polymer that is dissolved in an appropriate solvent, and a bioactive agent comprising a substantially water-insoluble antimicrobial metallic material that is solubilized in the coating solution so as to form a homogeneous phase or a substantially homogeneous phase with the hydrophilic polymer.
The coating solutions of the invention comprise one or more water-soluble hydrophilic polymers having polyfunctional groups, including but not limited to polyvinyl alcohol, polyvinylpyrrolidone, polyethyleneimine, polyacrylic acid, polyhydroxyethylmethacrylate, and copolymers and mixtures thereof.
In a currently preferred embodiment, the coating solutions of the invention comprise an aqueous solution of polyvinyl alcohol PVA. The substantially water-insoluble antimicrobial metallic material is chosen from, but not limited to, antimicrobial metal salts and metal complexes of silver, copper and zinc.
In a preferred embodiment, the substantially water-insoluble antimicrobial metallic material is a substantially water insoluble antimicrobial silver compounds including, but not limited to, silver halides, silver sulfazines, silver sulfadiazines, silver sulfonamides and silver sulfonylureas.
In a currently preferred embodiment the substantially water-insoluble antimicrobial metallic compound is silver sufladiazine, AgSD. In another preferred embodiment, antimicrobial coating formulations of the present invention additionally comprise a stabilizer compound that maintains the substantially water-insoluble antimicrobial metallic material, which is solubilized in the coating formulation, in a solubilized form in coatings obtained from the coating formulations.
Examples of such stabilizer compounds include antioxidant, photostabilizer or free-radical scavenger compounds, or mixtures thereof. Stabilizer compounds include, but are not limited to TiO2 and WO3 in any of their polymorphic forms.
Photostabilizing compounds include compounds such as magnesium silicate. In a currently preferred embodiment, the stabilizer compound is TiO2.
The substantially water-insoluble antimicrobial metallic material is dissolved in an aqueous acidic solution at an elevated temperature so as to effect complete dissolution of the metallic material.
The acidic solution containing the dissolved antimicrobial metallic material is then mixed with an aqueous solution of the hydrophilic polymer so as to maintain the antimicrobial metallic material in a solubilized form in the solution mixture in a homogeneous or substantially homogeneous aqueous phase, wherein the antimicrobial metallic material and the hydrophilic polymer are homogeneously dispersed in the aqueous coating solution.
In a currently preferred embodiment, a pre-determined amount of silver sulfadiazine is added to an aqueous solution of heated dilute nitric acid to bring the desired concentration of AgSD into solution.
Following the complete dissolution of the AgSD, a pre-determined amount of PVA having the desired percent hydrolysis and molecular weight range is added with stifling. The viscosity of the resulting coating solution comprising the PVA and solubilized AgSD ranges from about 10 to about 30 centipoises cPdepending on the characteristics of the PVA used.
In another embodiment, the AgSD solution in aqueous nitric acid is further mixed with buffer solution, such as for example, a phosphate buffer, prior to addition of PVA.
In another preferred embodiment of the invention, the coating formulation of the invention comprises a coating solution containing a hydrophilic polymer dissolved therein, a bioactive agent comprising a antimicrobial metallic material that is solubilized in the coating solution, and at least one stabilizer compound that is either dissolved in the coating solution to form a homogeneous phase, or suspended in the coating solution as a microparticulate dispersion.
In a currently preferred embodiment, the stabilizer compound is an inorganic oxide antioxidant compound, namely TiO2, which is suspended as a microparticular dispersion in the coating formulation.
The coating formulations of the invention is applied on a substrate surface using any of the standard coating methods known in the art such as dipping, spraying, rolling, etc.
In a preferred embodiment, the coating formulations are applied on substrate materials using a dipping process. The substrate is then mechanically withdrawn from the coating material such that a uniform coat is achieved.
The antimicrobial coatings of the invention comprising a bioactive agent that includes a solubilized antimicrobial metallic material and optionally, a stabilizer compound of are obtained by applying the antimicrobial coating formulations of the invention on a substrate material, subjecting the coating to either a partial or complete drying step, followed by reacting the coatings formed thereby to a cross-linking step.
The coatings of the invention may be produced on substrate materials either in their unfinished form sheet, granules, pellets etc. When the substrate to be coated contains a lumen, a vacuum or positive pressure may be applied to during the coating process to ensure that all parts of the substrate are contacted with the coating formulation.
The substrate material is optionally subjected to a spin step to aid in vertical and radial consistency of the resulting coating when utilizing a dip process during the withdrawal of the substrate material from the coating formulation. In one embodiment the spin rate during coated substrate material withdrawal is maintained between rpm.
In one embodiment, the withdrawal speed ranges between about 0. In another embodiment, the antimicrobial coating formulations of the invention comprising coating solutions are applied to the surface of a substrate material by a spray coat method.
The antimicrobial coating formulations is sprayed on the substrate material surface using standard spraying equipment and methods known in the art. Suitable spraying equipment include, but are not limited to, sprayers using pressurized air, and sprayers using an ultrasonic spray head, both of which aerosolize the coating solutions.
PVA molecular weight range, weight percentage, and percent hydrolysis are appropriately chosen so as to maximally aerosolize the coating solution.
For example, by overlaying two coating layers of approximately the same thickness, the effective concentration of AgSD released per cm2 of the coated substrate is effectively doubled.
Other variations include excluding the cross-linking step in the inner layers of with a multiple-layer coating, and limiting the cross-linking to the outermost coating layer.
The coating layer formed on substrate material surface by any of the methods described hereinabove is then dried by a suitable drying process that include, but not limited to, air-drying, infrared radiation, convection or radiation drying e.Photo Disclaimer: This photo may not reflect the actual final product you wish to purchase.
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This grant will pay for Kathryn to work for the AGSD-UK for two months. At the end of the two months, Kathryn will provide AGSD-UK with a well-written, easy-to-understand report on McArdle disease, which will be published on the AGSD-UK website and be made available as a .