News Column

"Metastable Silver Nanoparticle Composites" in Patent Application Approval Process

May 22, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- A patent application by the inventors OLDENBURG, STEVEN J. (San Diego, CA); BALDWIN, RICHARD K. (San Diego, CA), filed on October 25, 2013, was made available online on May 8, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application has not been assigned to a company or institution.

The following quote was obtained by the news editors from the background information supplied by the inventors: "Various embodiments of the present invention relate to a metastable silver nanoparticle composite, a process for its manufacture, and its use as a source for silver ions. In various embodiments, the composite comprises, consists essentially of, or consists of metastable silver nanoparticles that change shape when exposed to moisture, a stability modulant that controls the rate of the shape change, and a substrate to support the silver nanoparticles and the modulant.

"Silver is a well-known broad spectrum antimicrobial. Both ionic and nanoparticle forms of silver have been integrated into a number of biomedical devices to increase the efficacy of treatment. For example, Nucryst Pharmaceuticals has developed Acticoat (e.g. U.S. Pat. No. 6,989,156) which contains nanocrystalline silver that has enhanced solubility and sustained release of silver ions. Other silver dressings include Silvercell, aquacell and MeipexAG.

"All of the known silver dressing have ion release profiles that are a function of their local environment."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "In one embodiment, the control over the ion release profile is an important factor in the efficacy of treatment. There is a need for a more general class of composites where the time release of silver ions is modulated by the physical and chemical properties of the composite. Provided herein are several embodiments of a composite comprising metastable silver nanoparticles and a stability modulant having antimicrobial activity for use in the prevention of bacterial, fungal and yeast growth.

"Provided herein in one embodiment is a composite comprising a metastable silver nanoparticle, a stability modulant and a substrate, and where the silver nanoparticles undergo a change in shape when the composite is exposed to moisture.

"In one embodiment, the silver nanoparticles in the composite are coated with a stability modulant that modifies the silver nanoparticle's ion release rate in a dry environment or a moist environment.

"In one embodiment, the composite contains a coating that can is released when the composite is exposed to moisture, where the released coating modifies the silver nanoparticle's ion release rate in a moist environment.

"In one embodiment, the composite contains a stability modulant particle that is bound to the substrate and can dissolve in a moist environment over time to modify the silver nanoparticle's ion release rate in a moist environment. In some embodiments, stability modulants can either be etchants which include but are not limited to oxidants or protectants which include but are not limited to barriers to prevent silver ion release, reductants or both. In one embodiment, etchants increase the rate or amount of silver ion release while protectants slow or decrease the amount of silver ion release.

"In one embodiment, the color of the composite indicates the concentration and the shape of the silver nanoparticles bound to the substrate.

"In one embodiment, the composite is used to treat wounds.

"In one embodiment, a composite comprises a metastable silver nanoparticle and a stability modulant, where the silver nanoparticle undergoes a change in shape when the composite is exposed to moisture. In various embodiments, the composite further comprises a substrate. In various embodiments, the silver nanoparticles are nanoplates, nanopyramids, nanocubes, nanorods, or nanowires. In one embodiment, the silver nanoparticles are not spheres and undergo a reduction in aspect ratio when exposed to moisture. In one embodiment, the silver nanoparticles undergo a reduction in aspect ratio when exposed to water.

"In one embodiment, the nanoparticles are faceted and the vertices between their crystal faces undergo an increase in radius of curvature on exposure to moisture. In one embodiment, the stability modulant is a surface coating on the silver nanoparticles. In various embodiments, the surface coating is an oxide, a polymer, organic ligand, thiol, stimulus responsive polymer, polyvinylpyrollidone, silica, polystyrene, tannic acid, polyvinylalcohol, polystyrene or polyacetylene. In one embodiment, the stability modulant is a chemical that is dried onto the substrate. In one embodiment, the chemical is an oxidant. In various embodiments, the chemical is a borate salt, a bicarbonate salt, a carboxylic acid salt, sodium borate, sodium bicarbonate, sodium ascorbate, chlorine salts, primary amines or secondary amines. In one embodiment, the stability modulant is a mixture of etchants and protectants.

"In one embodiment, the stability modulant is a population of particles. In one embodiment, the particles release chlorine salts or chemicals with primary or secondary amines over a period of time greater than 30 minutes (e.g., 45 minutes, 50 minutes, 60 minutes, 2 hours or more).

"In one embodiment, the composite further comprises a protectant on the surface of the particle and a reductant bound to the substrate. In one embodiment, the substrate is a porous network of fibers. In various embodiments, the substrate is a sheet, sock, sleeve, wrap, shirt, pant, mesh, cloth, sponge, paper, filter, medical implant, medical dressing or bandage. In one embodiment, the silver nanoparticles are primarily crystalline.

"In one embodiment, at least 50% of the silver nanoparticle surface area is a silver ion lattice in the {111} crystal orientation. In one embodiment, the composite releases silver ions over a period of time greater than 30 minutes. In one embodiment, the silver nanoparticles are physisorbed, covalently bonded, or electrostatically bound to the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

"Further objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the invention, in which the following is a description of the drawings. The drawings are examples, and should not be used to limit the embodiments. Moreover, recitation of embodiments having stated features is not intended to exclude other embodiments having additional features or other embodiments incorporating different combinations of the stated features. Further, features in one embodiment (such as in one figure) may be combined with descriptions (and figures) of other embodiments.

"FIG. 1A illustrates one embodiment of a cubic nanoplate that has a small radius of curvature.

"FIG. 1B illustrates one embodiment of a cubic nanoplate with a larger radius of curvature.

"FIG. 2A illustrates one embodiment of a generally plate shaped nanoparticle with a specific width and thickness.

"FIG. 2B illustrates a one embodiment of a change of shape into another particle that has an increased thickness and a decreased width.

"FIG. 3 illustrates the optical spectra of one embodiment of silver nanoplates that have different aspect ratios.

"FIG. 4 shows a transmission electron microscopy (TEM) image of one embodiment of silver nanoplates after synthesis.

"FIG. 5 shows a TEM image of one embodiment of silver nanoplates after five days.

"FIG. 6 shows a chart that documents the optical shift associated with the shape change of silver nanoplates according to one embodiment of the invention.

"FIG. 7A illustrates one embodiment of a composite that contains fibers and metastable silver particles.

"FIG. 7B shows metastable silver particles that are plate shaped according to one embodiment of the invention.

"FIG. 7C shows metastable silver particles that are plate shaped and coated with a stability modulant according to one embodiment of the invention.

"FIG. 8A illustrates a one embodiment of a composite that contains fibers, metastable silver particles and a chemical stabilant.

"FIG. 8B illustrates the chemical coating component that is applied to the fiber and nanoparticles to form the composite according to one embodiment of the invention.

"FIG. 9 illustrates a composite that contains fibers, metastable silver particles and particles that release a stability modulant over time according to one embodiment of the invention.

"FIG. 10A illustrates a bandage that contains metastable silver particles attached to a woven mesh according to one embodiment of the invention.

"FIG. 10B illustrates a close-up view of the metastable silver particles attached to a woven mesh according to one embodiment of the invention."

URL and more information on this patent application, see: OLDENBURG, STEVEN J.; BALDWIN, RICHARD K. Metastable Silver Nanoparticle Composites. Filed October 25, 2013 and posted May 8, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3191&p=64&f=G&l=50&d=PG01&S1=20140501.PD.&OS=PD/20140501&RS=PD/20140501

Keywords for this news article include: Antimicrobials, Amines, Patents, Therapy, Nanoparticle, Nanotechnology, Organic Chemicals, Emerging Technologies.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


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Source: Politics & Government Week


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