Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
  • A01N59/20—Copper

Definitions

• This disclosure is directed to antimicrobial glass-ceramics, and in particular antimicrobial glass-ceramics containing silver, copper or a combination of silver and copper.
• the present disclosure is directed to the formation of an antimicrobial glass-ceramic ("GC") having an amorphous phase and a crystalline phase and an antimicrobial agent selected from the group consisting of silver, copper and a mixture of silver and copper.
• GC antimicrobial glass-ceramic
• Another aspect of the disclosure is a method of making a antimicrobial article having at least one selected antimicrobial agent therein, the method comprising the steps of providing a glass-ceramic substrate without an antimicrobial agent thereon, the glass-ceramic substrate having a crystalline component and an amorphous component; and subjecting said glass-ceramic substrate to an ion-exchange process using an ion-exchange bath containing at least one ion-exchangeable antimicrobial agent salt and an exchangeable alkali metal salt to thereby form a antimicrobial glass-ceramic article, wherein the antimicrobial agent(s) is selected from the group consisting of copper, silver and a mixture of copper and silver.
• the silver and copper, or mixture thereof can be zero valent existing in the GC as Ag° or Cu°, which is the metallic form; can be ionic and exist in the GC as Ag +1 , Cu +1 or Cu +2 ; or can be in the GC as a mixture of the zero valent and ionic forms of one or both agents, for example, Ag° and Cu +1 and/or Cu +2 , Ag +1 and Cu°, and other combination of the zero valent and ionic species.
• the antimicrobial agent can be incorporated into the GC by either (1) ion-exchange of a preformed GC using an ion-exchange bath containing one or both of the foregoing antimicrobial agents, or (2) by including one or both of the foregoing antimicrobial agents into batched materials used to prepare a glass that is then cerammed to form a GC.
• the antimicrobial agent will be present in the GC in ionic form, as the oxide, since nitrates of the antimicrobial agent can be used for the ion-exchange and because the nitrate species on the GC are easily decomposed during the ion-exchange process.
• the antimicrobial agent is also deemed present as the oxide due to the conditions of melting, forming, nucleating and ceramming the glass, all of which can be carried out in air. In either case the resulting antimicrobial agent containing GC can be used as-is or can be subjected to a reduction step.
• Figure 1 is an electron microprobe (EMP) analysis of a spodumene-type glass-ceramic after ion-exchange using a 5wt% AgN0 3 /95wt% NaN0 3 bath at 420°C for 20 minutes.
• EMP electron microprobe
• Figure 2A is an EMP analysis after ion-exchange using a 5wt%
• Figure 2B is an Ag map of the glass-ceramic of Figure 2A.
• Figure 3 is a photograph of a spodumene GC (a) after ion-exchange at 420°C for 20 minutes using 5wt% Ag in a NaN0 3 bath (top, GC is white) and (b) after reduction at 420°C for 5 hours in H 2 at 1 atmosphere pressure (bottom, GC is grey).
• Figure 4A and 4B are SEM micrographs of the surface ( Figure 4A) and edge
• Figures 5A-5C are SEM micrographs of the spodumene GC of Figures 4A/4B after reduction at 450°C for 5 hours in 1 atmosphere H 2 .
• Figure 6 is the EMP analysis of a spodumene GC containing 1 mole% CuO as-made after heat treatment at 1100°C.
• the term "antimicrobial,” means an agent(s) or material, or a surface containing the agent(s) or material that will kill or inhibit the growth of microbes from at least two of families consisting of bacteria, viruses and fungi.
• the term as used herein does not mean it will kill or inhibit the growth of all species microbes within such families, but that it will kill or inhibit the growth or one or more species of microbes from such families.
• the components of all the glass-ceramic compositions suitable for ion-exchange, or glasses that are suitable for ion-exchange before being cerammed into a glass-ceramic, are given in terms of weight percent (wt%) as the oxide unless indicated otherwise.
• glass-ceramic is defined herein as a material that has both an amorphous component and a crystalline component. Glass-ceramics are
• microcrystalline solids produced by the controlled devitrification of glass.
• glasses are batched, melted, fabricated to shape, and then converted by a heat treatment to a partially- crystalline material with a highly uniform
• microstructure The basis of controlled crystallization lies in efficient internal nucleation, which allows development of fine, randomly oriented grains minimizing voids, micro-cracks, or other porosity. Because of the nature of the crystalline microstructure, the mechanical properties, including strength, elasticity, fracture toughness, and abrasion resistance, may be higher in GCs than in glass.
• An aspect of the disclosure is an antimicrobial article comprising a substrate comprising a glass-ceramic having a crystalline component, an amorphous component, and at least one antimicrobial agent selected from the group consisting of silver, copper and a mixture of silver and copper.
• Another aspect of the disclosure is a method of making a antimicrobial article having at least one selected antimicrobial agent therein, the method comprising the steps of providing a glass-ceramic substrate without an antimicrobial agent thereon, the glass-ceramic substrate having a crystalline component and an amorphous component; and subjecting said glass-ceramic substrate to an ion-exchange process using an ion-exchange bath containing at least one ion-exchangeable antimicrobial agent salt and an exchangeable alkali metal salt to thereby form a antimicrobial glass-ceramic article, wherein the antimicrobial agent(s) is selected from the group consisting of copper, silver and a mixture of copper and silver.
• the antimicrobial GC article has a crystalline component in the range of 20-98 Vol% and an amorphous component in the range of 2-80 Vol%.
• the crystalline component can comprise a single crystalline phase of or a plurality of crystalline phases; that is, one or a plurality of crystalline phases.
• the antimicrobial GC article has a crystalline component in the range of 20-90 Vol% and an amorphous component in the range of 80-10 Vol%.
• the antimicrobial GC article has a crystalline component in the range of 40-90 Vol% and an amorphous component in the range of 60-10 Vol%.
• the crystalline component in some embodiments, is dispersed substantially uniformly within the glass component and exhibits a particle size ranging between 10 nm-20 microns, for example, 10 nm-19 microns, for example, 10 nm-18 microns, for example, 10 nm-17 microns, for example, 10 nm-16 microns, for example, 10 nm-15 microns, for example, 10 nm-14 microns, for example, 10 nm-13 microns, for example, 10 nm-12 microns, for example, 10 nm-1 1 microns, for example, 10 nm-10 microns, for example, 10 nm-9 microns, for example, 10 nm-8 microns, for example, 10 nm-7 microns, for example, 10 nm-6 microns, for example, 10 nm-5 microns, for example, 10 nm-4 microns, for example, 10 nm-3 microns, for example, 10 n
• the crystalline component has a particle size in the range of 10 nm-1 micron that is dispersed substantially uniformly within the glass component. In another embodiment the crystalline component has a particle size in the range of 10 nm-5 microns that is dispersed substantially uniformly within the glass component. In a further embodiment the crystalline component has a particle size in the range of 10 nm-2 microns that is dispersed substantially uniformly within the glass component.
• the crystalline component in some embodiments, is dispersed substantially uniformly within the glass component and exhibits an average particle size ranging between 10 nm-20 microns, for example, 10 nm-19 microns, for example, 10 nm-18 microns, for example, 10 nm-17 microns, for example, 10 nm-16 microns, for example, 10 nm-15 microns, for example, 10 nm-14 microns, for example, 10 nm-13 microns, for example, 10 nm-12 microns, for example, 10 nm-11 microns, for example, 10 nm-10 microns, for example, 10 nm-9 microns, for example, 10 nm-8 microns, for example, 10 nm-7 microns, for example, 10 nm-6 microns, for example, 10 nm-5 microns, for example, 10 nm-4 microns, for example, 10 nm-3 microns, for example, 10 nm
• the crystalline component has an average particle size in the range of 10 nm-1 micron that is dispersed substantially uniformly within the glass component. In another embodiment the crystalline component has an average particle size in the range of 10 nm-5 microns that is dispersed substantially uniformly within the glass component. In a further embodiment the crystalline component has an average particle size in the range of 10 nm-2 microns that is dispersed substantially uniformly within the glass component.
• a GC article without an antimicrobial agent therein or thereon is provided and subjected to an ion-exchange process using an ion-exchange bath containing at least one ion-exchangeable antimicrobial agent salt and an exchangeable alkali metal salt.
• the antimicrobial agent salt and the alkali metal salt are present in the bath as a nitrate.
• the alkali metal can be, for example, sodium nitrate, potassium nitrate or a mixture thereof.
• concentration of the salts containing the antimicrobial agent(s) in the ion-exchange bath in some embodiments, is in the range of 1 wt% to 100 wt%.
• the balance of the bath can be a salt of an alkali metal or an alkaline earth metal.
• concentration of the salts containing the antimicrobial agent(s) in the ion-exchange bath is in the range of 5 wt% to 100 wt%.
• the concentration of the silver salt or copper salt, or mixture thereof, in the ion-exchange bath can be in the range of 0.01 wt% to 10 wt%. In one embodiment, the concentration of the silver salt or copper salt, or mixture thereof, in the ion-exchange bath is in the range of 0.01 wt% to 5 wt%.
• the ion-exchange temperatures can be in the range of 300-500°C with an ion-exchange time in the range of greater than 5 minutes to less than 6 hour. The temperature range could be higher if sulfate is present. The exact choice of time and temperature will be dependent on the depth of layer sought to be exchanged into the GC.
• the ion-exchange is carried out at a temperature in the range of 350-420°C, depending for example on the bath used, for a time of one hour or less time; for example without limitation, at a temperature of 420°C for a time in the range of 5 minutes to 20 minutes. If it is desired to have the antimicrobial ion-exchanged deeply into the GC, the ion-exchange can be carried out at higher temperatures for a longer time, for example without limitation, at a temperature of 450°C for a time in the range of 4-6 hours.
• the antimicrobial agent in the antimicrobial article is silver and the article has a surface concentration of silver, determined as Ag 2 0, of 1- 20 wt%. In some embodiments, in the antimicrobial article the antimicrobial agent is copper and the article has a surface concentration of copper, determined as CuO, of 1- 20 wt%. In some embodiments, in the antimicrobial article the antimicrobial agent is a mixture of copper and silver and the article has a surface concentration of copper and silver, determined as Ag 2 0 and CuO, of 1-20 wt% .
• the antimicrobial agent in the antimicrobial article is silver and the article has a surface concentration of silver, determined as Ag 2 0, of 6 wt% or less. In some embodiments, in the antimicrobial article the antimicrobial agent is copper and the article has a surface concentration of copper, determined as CuO, of 6 wt% or less. In some embodiments, in the antimicrobial article the antimicrobial agent is a mixture of copper and silver and the article has a surface concentration of copper and silver, determined as Ag 2 0 and CuO, of 6 wt% or less.
• the antimicrobial agent in the antimicrobial article is silver and the article has a surface concentration of silver, determined as Ag 2 0, of 1-6 wt%. In some embodiments, in the antimicrobial article the antimicrobial agent is copper and the article has a surface concentration of copper, determined as CuO, of 1- 6 wt%. In some embodiments, in the antimicrobial article the antimicrobial agent is a mixture of copper and silver and the article has a surface concentration of copper and silver, determined as Ag 2 0 and CuO, of 1-6 wt%.
• GC-forming components such as sand, sodium and/or potassium oxide, aluminum oxide, borate magnesia and/or other components as need to form a specific GC material were dry mixed in an appropriate vessel and a solution of the antimicrobial agent salt(s) was added to the dry materials during mixing, for example, by spraying the solution of antimicrobials agent s into the vessel.
• the solution is an aqueous solution.
• the methods can further comprising reducing the resulting antimicrobial agent(s) in the antimicrobial containing GC by heating in a reducing atmosphere at a selected temperature for a selected time to reduce the antimicrobial agent(s) to the zero valent form.
• the reducing conditions use a hydrogen atmosphere, for example, a pure H 2 environment, at a pressure in the range of 1-10 atmospheres at a temperature in the range of from 300°C to 600°C, for example, 350°C to 500°C for a time in the range of from 1-6 hours, for example, 2-6 hours or, for example, 1-5 hours.
• Other reducing substance such as forming gas can also be used.
• Glass-ceramics found useful for preparing antimicrobial GCs contain 20-98 Vol.% crystalline component and 2-80 Vol.% glass component.
• the antimicrobial glass-ceramics can be optically transparent or non-transparent and they can be colored or non-colored (that is, clear), where clear means no visible coloration.
• a transparent glass-ceramic can be either clear or colored.
• White and black are considered colors herein.
• the GC materials that can be used in practicing the disclosure can be selected from the group consisting of beta-spodumene solid solution (including both Li and Cu types, and solid solutions of Li, Cu, Mg, and Na), beta-quartz solid solutions
• Exemplary GCs used herein include beta-spodumene and beta-quartz solid solutions and Macor (Corning Incorporated) which is a machinable, white, odorless, porcelain-like (in appearance) GC material that has the appearance of porcelain and is 55 Vol% fluorophlogopite mica and 45 Vol% borosilicate glass.
• the antimicrobial GC is optically transparent and has a color or is uncolored. In another embodiment, the antimicrobial GC is translucent or opaque and has a color.
• the GCs may have compositions as described by the ranges in Table 1. The compositions are listed in weight percent.
• Figure 1 is an electron microprobe (EMP) analysis of a spodumene-type glass-ceramic after ion-exchange using a 5wt% AgN0 3 /95wt% NaN0 3 bath at 420°C for 20 minutes.
• Line 10 shows the wt % of Ag 2 0 present in the GC as a function of depth in microns.
• Figure 2A is an EMP analysis after ion-exchange using a 5wt%
• FIG. 2B is an Ag map of the glass-ceramic of Figure 2A. The light areas 12 show increased Ag concentration.
• Figure 3 is a photograph of a spodumene GC (a) after ion-exchange at 420°C for 20 minutes using 5wt% Ag in a NaN0 3 bath (top, GC is white) and (b) after reduction at 420°C for 5 hours in H 2 at 1 atmosphere pressure (bottom, GC is grey).
• Figure 4A and 4B are SEM micrographs of the surface (Figure 4A) and edge ( Figure 4B) of a spodumene GC after ion-exchange using a 5wt% AgN0 3 /95wt% NaN0 3 bath at 420°C for 20 minutes.
• Figures 5A-5C are SEM micrographs of the spodumene GC of Figures 4A/4B after reduction at 450°C for 5 hours in 1 atmosphere H 2 .
• Figure 6 is the EMP analysis of a spodumene GC containing 1 mole% CuO as-made after heat treatment at 1100 °C.
• compositions are shown in Table 2, Compositions A and B are examples of MacorTM and nepheline compositions, respectively, and examples C, D, E, and F are examples of beta-quartz. Table 3, examples K, L, M, N, O, and P, shows examples of beta-spodumene.
• Example Q in Table 3 is an exemplary fluormica glass- ceramic.
• Example R in Table 3 is an exemplary canasite glass-ceramic.
• Example S in Table 3 is an exemplary spodumene glass-ceramic.
• Tables 2 and 3 give
• the GCs listed in Tables 1, 2, and 3 can be used as a base GC and the ion-exchanged to provide or increase the amount of copper, silver, or combinations thereof in the GC.
• the GCs listed in Tables 1, 2, and 3 can have concentrations of silver, copper, or combinations thereof in the range of from 0- 20 wt%, for example, 1-20 wt%, for example, 1-19 wt%, for example, 1-18 wt%, for example, 1-17 wt%, for example, 1-16 wt%, for example, 1-15 wt %, for example, 1- 14 wt%, for example, 1-13 wt%, for example, 1-12 wt%, for example, 1-1 1 wt%, for example, 1-10 wt%, for example, 1-9 wt%, for example, 1-8 wt%, for example, 1-7 wt%, for example, 1-6 wt%, for example, 1-5 wt%, or, for example, 2-20 wt%, for example, 3-20 wt%, for example, 4-20 wt%, for example, 5-20 wt%, for example, 6- 20 wt
• Antimicrobial agent containing GCs have been tested for their antimicrobial activity, for example, using methods described below, and some of the antimicrobial GCs have a Log Reduction of >2.
• the article has an antimicrobial Log Reduction of >0.2, for example, >0.5, for example, >1, for example, >1.5, for example, >2, for example, >2.5, for example, >3, for example, >3.5, for example, >4, for example, >4.5, for example, >5.
• the article has an antiviral Log Reduction of >4 and an antibacterial Log Reduction >5.
• the article is capable of inhibiting at least 2 microbial species to a Log Reduction >1 within 1 hour.
• the article has an antibacterial Log Reduction of greater than 4 after 6 hours.
• Antibacterial testing for example, antibacterial-wet tests were performed on several exemplary glass-ceramics. Each testing sample glass-ceramic was cut into a glass-ceramic slide of lx 1 inch and put into petridish. Three uncoated glass-ceramic slides were used as negative controls. Gram negative E. coli bacteria were suspended in a 1/500 luria broth (LB) medium at a concentration of lX10 6 cell/ml. 156 ⁇ 1 of E. coli cell suspension was placed onto each sample surface and held in close contact by using a sterilized laboratory PARAFILM, and incubated for 6 hours at 37 C at saturation humidity (>95% relative humidity). Each sample was done in triplicate.
• LB luria broth
• PARAFILM sterilized laboratory PARAFILM
• PBS Phosphate Buffered Saline
• Antibacterial testing for example, antibacterial-dry tests were performed on several exemplary glass-ceramics. Each testing sample glass-ceramic was cut into a glass-ceramic slide of lx 1 inch 2 and put into petridish in triplicate. Non copper doped (uncoated) glass-ceramic slides were used as negative controls. Gram positive Staphylococcus aureus bacterial was cultured for at least 3 consecutive days before and on the day of testing, the inocula was culture for at least 48hours. The bacterial culture was Vortexed, serum(5% final concentration) was added and Triton X- 100(fmal concentration 0.01%) was added to the inocula.
• This exemplary GC was optically translucent to transparent. The treatment in H 2 and antimicrobial activity is listed in Table 4.
• An exemplary spodumene GC with Cu, example E in Table 2 had a crystal phase developed using the following thermal treatment: 720 ° C/2h+ 1000 ° C/4h to produce spodumene phase.
• the treatment in H 2 and antimicrobial activity is listed in Table 5.
• the treatment in H 2 and antimicrobial activity is listed in Table 6.
• An exemplary spodumene ion-exchanged GC with Ag (Ag was added by 5% AgN0 3 in a bath concentration ion-exchange), example S is the base GC prior to ion- exchange in Table 3, had a crystal phase developed using the following thermal treatment: 720 ° C/2h+ 1000 ° C/4h to produce spodumene phase.
• the measured wt% of Ag 2 0 was 16 wt%.
• the treatment in H 2 and antimicrobial activity is listed in Table 7.
• An exemplary spodumene ion-exchanged GC with Ag is the base GC prior to ion-exchange in Table 3, had a crystal phase developed using the following thermal treatment: 720 ° C/2h+ 1000 ° C/4h to produce spodumene phase.
• Ag was added by AgN0 3 ion-exchange at 350 ° C/10min as shown in Table 8.
• the GC was also Na ion-exchanged at 390 ° C/3.5h to strengthen the GC.
• the treatment in H 2 and antimicrobial activity is listed in Table 8.
• An exemplary mica GC with Cu, example A in Table 2 had a crystal phase developed using the following thermal treatment: 720 ° C/2h+ 950 ° C/4h to produce mica phase.
• the treatment in H 2 and antimicrobial activity is listed in Table 9.
• An exemplary canasite GC with Cu is the base GC prior to ion- exchange in Table 3, had a crystal phase developed using the following thermal treatment: 720 ° C/2h+ 850 ° C/4h to produce canasite phase.
• the first exemplary canasite in Table 10 was ion-exchanged with Ag at 450 ° C/20min with 5% AgN0 3 .
• the treatment in H 2 and antimicrobial activity is listed in Table 10.
• An exemplary Macor GC with Cu, example A in Table 2 had a crystal phase developed using the following thermal treatment: 720 ° C/2h+ 950 ° C/4h to produce MacorTM phase.
• the first exemplary MacorTM in Table 11 was ion- exchanged with Ag at 450 ° C/20min with 5% AgN0 3 .
• the treatment in H 2 and antimicrobial activity is listed in Table 1 1.
• the treatment in H 2 and antimicrobial activity is listed in Table 12.

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