HK1197715B - Stabilized hypohalous acid solutions - Google Patents

Description

Stable hypohalous acid solutions

RELATED APPLICATIONS

This application claims benefit and priority from U.S. provisional application 61/454,383, filed 3/18/2011 and U.S. provisional application 61/526,149, filed 8/22/2011, each of which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates to stable solutions and formulations of hypohalous acids, such as hypochlorous acid (HOCl), and methods of making and using the same. The solution can be used to clean and/or disinfect surfaces, food such as fruits, vegetables and crops, or mammalian tissue (including wounds). The solution can also be used for the preservation of agricultural products and cut flowers.

Background

Hypochlorous acid is an oxidizing and microbicidal agent that is produced by the natural immune system of the human body to fight infections. Hypochlorous acid is produced as the final step of the Oxidative Burst Pathway (Oxidative Burst Pathway), and a large amount of hypochlorous acid is released into phagocytic vesicles to destroy invading microorganisms. It is believed that hypochlorous acid exerts its biocidal effect by: attack surface and plasma membrane proteins, impairing solute transport and salt balance of bacterial cells (Pieterson et al, Waters SA,22 (1): 43-48 (1996)). Coli exposed to hypochlorous acid loses viability in less than 100ms due to inactivation of many vital systems (Fair et al, 40j.am. water Works assoc.1051-61 (1940)). Hypochlorous acid at 2.6ppm resulted in 100% growth inhibition of E.coli in the diluted bacterial suspension in about 5 minutes (Chesney et al, 178J. bacteriol.2131-2135 (1996)). According to Chemistry of Watertreatment (2)^ndEdition), s.d.faust and o.m.aly (1998), only 0.08ppm (for a.aerogenes), 0.06ppm (for s.typhosa), 0.05ppm (for shigella dysenteriae), and 0.03ppm (for s.dysenteriae) are required for 100% kill within 5 minutesIn E.coli).

Although hypochlorous acid is microbicidal, it is not significantly toxic to human or animal cells, at least in part because human and animal cells have a broad, highly effective defense mechanism known as the Antioxidant Defense System (ADS).

Hypohalous acids have a wide range of applications where control of microbial contamination is important, for example in the care and treatment of wounds, disinfection of hard surfaces such as medical or dental equipment, food safety and handling, water treatment and other industrial and agricultural applications.

One limitation associated with hypochlorous acid solutions is their stability, which has limited many commercial uses to the following: in these cases the solution may be prepared in situ for relatively immediate use. Existing alternatives include a dajin solution for wound care, which is a diluted sodium hypochlorite solution (0.5%) prepared by the following method: sodium hypochlorite (5.25%), sodium bicarbonate/carbonate (1%), and clean tap water were mixed. However, dacron solution has a high pH and therefore causes pain and burning in the wound treatment, along with rash, itching, swelling, urticaria, and/or blisters. Also, for at lower pH: (<8.5), the Dajin solution is unstable and unsuitable. Another alternative is Microcyn^TMAnd (3) solution. Although Microcyn has a2 year shelf life, its drawbacks are a limited level of Available Free Chlorine (AFC) of about 80ppm (pH of 7.4), and a lower percentage of hypochlorous acid, which can limit its biocidal efficacy. EcaFlo^TMCan be used for hard surface disinfection. In addition to the high sodium chloride content, this solution contains equimolar amounts of hypochlorite and hypochlorous acid. The pH of this solution was about 7.5 and the AFC content of the solution was about 460 ppm. This solution has a relatively short shelf life of 30 days.

There is an unmet need for hypohalous acid solutions that have high AFC content, sufficient stability and/or other properties needed for commercial use in medical and other commercial environments, and that are neither irritating or harmful to humans. The present invention meets these and other objectives.

Disclosure of Invention

The present invention provides stable hypohalous acid solutions or formulations thereof that can be conventionally packaged for sale or stored for later use when needed. The invention also provides methods of making stable hypohalous acid solutions or formulations thereof, and methods for use in disinfecting mammalian tissue (including wounds and burns), disinfecting or cleaning hard surfaces, treating (e.g., preserving and/or disinfecting) food or cut flowers, and the like.

In one aspect, the present invention provides a stable hypohalous acid solution. The solution contains a stabilizing amount of Dissolved Inorganic Carbon (DIC), which may be in the form of: alkali metal bicarbonate, alkaline earth metal bicarbonate, alkali metal carbonate, or alkaline earth metal carbonate. The solution can have an available free chlorine (available free chlorine, AFC) content of about 10ppm to about 10,000ppm (parts per million), and a pH of about 4.0 to about 7.5. For example, in some embodiments, the solution has a pH of about 5 to about 7. In some embodiments, the solution contains hypochlorous acid and is prepared by electrolysis of brine. The solution is stabilized for at least one month, as determined by changes in pH and/or AFC over time, but in various embodiments, the solution is stabilized for at least six months, at least one year, or more.

In some embodiments, sodium bicarbonate is introduced into the solution at a molar ratio of about 5:1 to about 1:5 relative to AFC content. For example, sodium bicarbonate can be added at a molar ratio of about 1:1, about 1:2, or about 1:3 or greater (i.e., more dilute) relative to AFC content (e.g., hypohalous acid content). In some embodiments, sodium bicarbonate is introduced into the solution at a level of about 1:1 to about 1:2 relative to AFC content. While in some embodiments the solution may contain a phosphate buffer, in other embodiments the solution contains no phosphate buffer, or only a limited amount of phosphate buffer. For example, the solution may include HOCl produced by electrolysis of brine, and the solution may have an AFC content of about 100ppm to about 500ppm, a pH of about 5 to about 7, a salinity of about 0.02% to about 1.0%, and an amount of dissolved inorganic carbon of about 300mg/L to about 1500 mg/L. In some embodiments, the salinity of the solution does not affect the amount of bicarbonate required for solution stabilization. In some embodiments, the HOCl solution is formulated as a hydrogel.

In another aspect, the present invention provides a method of preparing a stable hypohalous acid solution. The methods include introducing DIC (e.g., in the form of a carbonate or bicarbonate) by addition to an electrolyte for electrochemical treatment, or by direct addition to an electrolyzed solution comprising a hypohalous acid (e.g., HOCl).

Other aspects of the invention provide methods of disinfecting, cleaning, or treating mammalian tissue, such as wounds, burns, or skin disorders, or methods of sanitizing, disinfecting, or cleaning hard surfaces, or methods of treating or preserving food or agricultural products or cut flowers. Due to the stability of hypohalous acid solutions and formulations, this method need not be performed close to the preparation of biocidal solutions. Moreover, as shown herein, the stable hypohalous acid solutions of the present invention maintain activity even in the presence of high organic loading. In other embodiments, the present invention provides methods of treating skin conditions including skin diseases, rosacea (rosasea), skin infections, skin allergies, psoriasis, or acne. In such embodiments, the HOCl may be formulated as a hydrogel.

Other aspects of the invention will become apparent from the following detailed description of the invention.

Drawings

FIG. 1 shows the change in pH over time of a HOCl solution (A) stored at room temperature or a HOCl solution (B) stored at less than 20 ℃.

FIG. 2 shows the change in AFC over time for HOCl solutions stored at room temperature (A) or at less than 20 deg.C (B).

FIG. 3 shows the AFC degradation over storage time in bottled HOCl solutions containing bicarbonate ("unbuffered"), or containing bicarbonate and phosphate buffers.

FIG. 4 shows the change in pH and AFC for HOCl solutions containing bicarbonate but no phosphate buffer.

Fig. 5 shows the reduction of clostridium difficile spores in the presence of high organic load. The solutions tested were as follows: AFC at pH6.7,250ppm, NaHCO at 400mg/L₃(ii) a AFC at pH6.7,480mg/L, 0.0NaHCO₃(ii) a AFC at pH6.3,480ppm, and NaHCO at 1000mg/L₃。

FIG. 6 shows the results of a prolonged stability study of HOCl by electrochemical treatment of NaHCO at pH5.4 of interest₃The enriched NaCl solution was produced, bottled in polyethylene terephthalate (PET) containers and stored at room temperature.

Figure 7 shows the stability of HOCl added to a vessel containing dry sodium bicarbonate. Figure 7A shows pH stability. FIG. 7B shows the stability of AFC content.

Figure 8 shows the effect of bicarbonate on pH and solution stability in hypochlorous acid solutions with target pH for agricultural applications.

Figure 9 shows the change in pH after formulation into a hydrogel.

Detailed Description

The present invention provides stable hypohalous acid solutions or formulations thereof that can be conventionally packaged for sale or stored for later use when needed. The invention also provides methods of preparing the stable hypohalous acid solutions, and methods for use in disinfecting mammalian tissue (including wounds and burns), disinfecting or cleaning surfaces, or treating or preserving food or cut flowers.

In one aspect, the present invention provides stable hypohalous acid solutions or formulations thereof. The solution contains a stabilizing amount of Dissolved Inorganic Carbon (DIC), such as an alkali metal bicarbonate, an alkaline earth metal bicarbonate, an alkali metal carbonate, or an alkaline earth metal carbonate. The solution can have an Available Free Chlorine (AFC) content of about 10ppm to about 10,000ppm (parts per million), and a pH of about 4.0 to about 7.5. In some embodiments, the solution contains hypochlorous acid and is prepared by electrolysis of brine. The solution is stabilized for at least one month, as determined by changes in pH and/or AFC over time, but in various embodiments, the solution is stabilized for at least six months, at least one year, or more.

The hypohalous acid solution may be produced by electrolysis of a halogen salt, such as sodium chloride, and may comprise a mixture of oxidising species, such as primarily hypochlorous acid and sodium hypochlorite. Hypochlorous acid and hypochlorite are in equilibrium, and the location of equilibrium is primarily determined by pH (i.e., pH affects the concentration of each component). The electrolyzed sodium chloride solution having a pH of 5.1-6.0 has a purity of about 95% or more hypochlorous acid. Thus, the supplied electrolyzed solution may have a pH of about 4.0 to about 7.5, but in some embodiments has a pH of about 4.4 to about 7.0, or a pH of about 5 to about 7, or a pH of about 5.4 to about 6.4, or a pH of about 5.0 to about 6.4. At a pH of about 5.4, the solution will contain predominantly (close to 100%) hypochlorous acid relative to hypochlorite.

Although the solution may include, or consist essentially of, hypochlorous acid as an active agent, in some embodiments, the solution may contain other hypohalous acids (e.g., HOBr, or mixtures thereof). In some embodiments, the solution contains other oxidizing or free radical generating species, such as hypohalites (e.g., hypochlorites), hydrogenOxide, H₂O₂And O₃And the like.

The biocidal activity of the solution can be expressed in terms of available free chlorine or AFC. Although the present invention is applicable to an AFC range of about 10ppm to about 10,000ppm (or to about 5000ppm), in some embodiments, the solution has a relatively high AFC content and is applicable to mammalian tissue or agricultural products. For example, the solution may have an AFC content of about 100ppm to 1000ppm, alternatively 100ppm to 500ppm, alternatively about 150ppm to about 250 ppm. Other AFC levels may also be used and may be selected based on the intended application. For example, without any limitation, for surface disinfection, AFC may be about 140ppm to about 2000ppm, or about 400ppm to about 1000 ppm.

While hypochlorous acid may be chemically generated (e.g., by acidifying hypochlorite) according to some embodiments, hypohalous acid may also be electrolytically generated. Electrochemical production of hypohalous acids is by treatment of halide-based electrolytes in diaphragm-type cells. Electrochemical treatment of saline is described, for example, in U.S. Pat. No. 7,303,660, U.S. Pat. No. 7,828,942, and U.S. Pat. No. 7,897,023, which are incorporated herein by reference in their entirety.

The solution uses a stabilizing amount of DIC, which can be an alkali metal bicarbonate, alkali metal carbonate, alkaline earth metal bicarbonate, or alkaline earth metal carbonate, such as sodium, potassium, calcium, or magnesium. In some embodiments, the bicarbonate or carbonate is added prior to forming the hypohalous acid (e.g., by electrochemical treatment), and in other embodiments, the bicarbonate or carbonate is added to the solution after forming the hypohalous acid. For example, one or more bicarbonate salts or one or more carbonate salts may be added to the precursor solution, the electrolyte, and/or the final solution.

DIC is introduced in a "stabilizing amount" which can be determined from the change in pH or AFC content of the solution over time. Typically, the solution is considered stable if the amount of AFC does not drop below about 75% of the initial value over about 6 months. In some embodiments, AFC content is stable for at least one year from the date the solution was produced. Moreover, the stability of the solution can be measured in terms of pH. Typically, the solution is considered stable if the pH does not change by 1 unit over about 6 months. In some embodiments, the pH is stable for at least one year from the date the solution is prepared. For greater stability, the solution should be stored at 25 ℃ or 20 ℃ or less. 25 ℃ and 20 ℃ are reference temperatures for determining stability. For stability testing, the solutions were packaged in HDPE bottles, stored in the dark, and stored closed.

The amount of stability in DIC (e.g., as added carbonate or bicarbonate) can be determined from AFC content. For example, in some embodiments, a stabilizing amount of carbonate or bicarbonate is introduced into the solution at a molar ratio of about 5:1 to 1:5 relative to the level of AFC. In some embodiments, the bicarbonate or carbonate is introduced into the solution in at least an equimolar amount relative to the AFC content (e.g., hypochlorous acid content). In other embodiments, the DIC (e.g., bicarbonate or carbonate) is introduced at about 5:1, about 2:1, about 1:2, about 1:3, or about 1:5 relative to AFC content. In various embodiments, other buffering components, such as phosphate buffers, are not used, or are minimally used. For example, for a solution having an AFC content of about 200ppm to about 500ppm, the carbonate or bicarbonate can be introduced in an amount of about 300mg/L to about 1500mg/L to stabilize the solution. In some embodiments, such solutions are stabilized by the introduction of about 400mg/L to about 1000mg/L carbonate or bicarbonate.

Without being bound by theory, Dissolved Inorganic Carbon (DIC) (which generally includes carbonate, bicarbonate, carbonic acid, and dissolved CO)₂) Provide low or minimal buffering capacity in the target pH range of the solutions and compositions described herein. However, these solutions are effectively stabilized such that the solutions and compositions do not rely on "on-demand" production. The stabilizing effect may be due in part to the free radical scavenging ability of DIC, thereby slowing HAnd (4) decomposing the OCl. In addition, solutions prepared by electrochemical treatment of bicarbonate-enriched sodium chloride solutions (relative to chemical acidification with an equivalent amount of carbonate/bicarbonate stabilized sodium hypochlorite) have different properties in terms of DIC, and the stabilization effect can be different.

In some embodiments, as shown in fig. 5, the addition of alkali metal bicarbonate, alkali metal carbonate, alkaline earth metal bicarbonate, or alkaline earth metal carbonate provides enhanced biocidal efficacy for treating microorganisms or biofilms, particularly in the presence of high organic loading.

Although the hypohalous acid solution may be in liquid form, the solution may take the form of a cream (cream), a gel (e.g., a silicone-based gel), and/or a foam by the addition of conventional ingredients known in the art. For example, topical formulations of electrochemical solutions are disclosed in US2005/0196462, the entire contents of which are incorporated herein by reference. In these embodiments, the formulation is better contained near the site of application by limiting the flow of the solution away. Moreover, conventional applicators for creams, foams, and the like are known and may be used in accordance with the present invention. The solutions of the present invention are particularly suitable for hydrogel formulations due to their potential to provide low conductivity, even at relatively high AFC content and "skin-friendly" pH levels.

In certain embodiments using hydrogel formulations, the compositions have an AFC content of greater than about 100ppm, greater than about 150ppm, greater than about 200ppm, greater than about 250ppm, or greater than about 300 ppm. Also, the formulation may have a viscosity of from about 0.5mS/cm to about 12mS/cm, such as from about 1mS/cm to about 10mS/cm in some embodiments. Also, the hydrogel formulation has a pH of about 5 to about 7 in some embodiments, or about 5 to about 6.5 in other embodiments. Hydrogels can be prepared from a silicate-based carrier such as sodium magnesium fluorosilicate (e.g., about 0.5% to about 5%), and additional buffering agents can be used to achieve the target pH. An exemplary buffer is phosphoric acid.

The stable solution may be packaged for storage or sale using any suitable container, such as any suitable plastic or glass bottle, or bag (e.g., plastic bag), tube, or canister (e.g., spray or aerosol canister). In some embodiments, the packaging material has a slight permeability to gases, such as CO₂And O₂. The containers may be transparent, or opaque, such that they are opaque to light, and may have any unit volume, for example, about 100ml, about 125ml, about 250ml, about 0.5 liters, about 1 liter, about 5 liters, about 10 liters, or greater.

The hypochlorous acid solution of the present invention may also be hypertonic, hypotonic, or isotonic with respect to physiological fluids (blood, plasma, tears, etc.). Alternatively, the solution may contain varying levels of salinity, for example, 0.01% to about 2.0%. Typically, when intended for use in medicine, the solution contains from about 0.02% to about 0.9% w/v NaCl. In some embodiments, the solution may be a physiological saline solution (about 0.9% w/v NaCl). In some embodiments, the solution may contain about 0.01-2.0% w/v of one or more salts, such as halide salts, e.g., NaCl, KCl, or a mixture of salts or halide salts. The salt, or halide salt, may be a salt of an alkali or alkaline earth metal, such as sodium, potassium, calcium, or magnesium. In some embodiments, the electrolyzed solution is produced using a mixture of physiologically balanced salts, as disclosed in U.S. patent 6,426,066, which is incorporated herein by reference in its entirety. Such salts may include potassium halides (e.g., KCl) and magnesium halides (e.g., MgCl)₂)。

In another aspect, the present invention provides a method of preparing a stable hypohalous acid solution. The method includes introducing a carbonate or bicarbonate salt into an electrolyte for electrochemical treatment, or directly into an electrolyzed solution comprising a hypohalous acid (e.g., HOCl).

For example, the electrolyzed solution or other hypohalous acid solution can be diluted with water or an aqueous solution containing bicarbonate or carbonate. In other embodiments, a diluted hypohalous acid solution (e.g., having a desired AFC content) is added to a vessel comprising a dried alkali metal bicarbonate, alkali metal carbonate, alkaline earth metal bicarbonate, or alkaline earth metal carbonate. The latter is an effective method for producing hypohalous acid solutions of low ionic strength, especially for hydrogel formulations.

Stable hypochlorous acid solutions (e.g., solutions of greater than 90%, 95%, or 97% HOCl) can be obtained by electrolysis of aqueous saline solutions, as described in U.S. patent 7,276,255, which is incorporated herein by reference in its entirety, or can be prepared by any suitable method or apparatus by introducing bicarbonate or carbonate salts into dry electrolyte (electrolyte) or electrolysis solutions. Carbonates or bicarbonates may be added to the dry electrolyte depending on the desired AFC content of the resulting solution, as detailed herein. The hypochlorous acid solution can be prepared by the following method: the carbonate/bicarbonate containing brine solution was passed through a coated titanium electrode separated by a semipermeable ceramic membrane at a current of about 6-9 amps. Electrochemical treatment of saline is described, for example, in U.S. Pat. No. 7,303,660, U.S. Pat. No. 7,828,942, and U.S. Pat. No. 7,897,023, which are incorporated herein by reference.

Other aspects of the invention provide methods of disinfecting or cleaning mammalian tissue, such as wounds or burns, or disinfecting or cleaning hard surfaces, or treating or preserving food or cut flowers. Due to the stability of hypohalous acid solutions, this method need not be carried out close to the preparation of the biocidal solution, and the solution can be prepared well before use.

The solutions and formulations of the present invention are useful as germicidal, disinfectant and biocidal solutions for human and animal care. The solution is harmless, non-irritating, non-sensitizing to the skin, non-irritating to the eyes, harmless if swallowed, and shows no signs of mutagenic activity. For example, the methods of the present invention provide for the wetting, lubricating, irrigating, cleaning, deodorizing, disinfecting, or debriding of wounds by rinsing, washing, or impregnating the wound with or in a stable or stored hypohalous acid solution, or by applying the solution to the wound and/or wound dressing. The wound may or may not be infected and thus the method of the invention may be used to treat infected wounds and may be used to prevent infection of uninfected wounds.

In one aspect, the present invention provides conventional means for wound care and treatment and may be used in combination with the apparatus and methods described in u.s.2010/030132, the entire contents of which are incorporated herein by reference. For example, the method may include supplying a stable solution to the wound site by one or more of soaking, scrubbing, pulse irrigation, water jet (hydro-surgery), and ultrasound, thereby effectively debriding and disinfecting the wound or tissue. The solution may be delivered before, during, and/or after negative pressure wound therapy to promote proper wound healing physiology. In these embodiments, the methods may use a wound dressing to coordinate debridement with negative pressure therapy by instillation of hypochlorous acid. Thus, the present invention may be used in combination with a wound treatment apparatus and/or wound dressing.

For example, in some embodiments, the present invention allows for first soaking and/or scrubbing with a stable hypochlorous acid solution to debride and disinfect the wound or tissue, and then applying negative pressure to the wound or tissue (as described herein) using the stable hypochlorous acid solution as a rinsing fluid to control the bioburden of the wound, remove excess exudate, and promote the formation of granulation tissue. Optionally, the method also includes seamlessly switching to stable hypohalous acid solution perfusion (e.g., active or passive perfusion without negative pressure). This seamless transition may be performed by a wound dressing that allows for controlled infusion of a stable hypochlorous acid solution with a controlled vacuum source. In these embodiments, once the endpoint of negative pressure therapy is reached, continued cell proliferation and regeneration continues without disruption of the wound bed.

In some embodiments of the invention, the wound in need of care is a pressure ulcer of the skin of grade I-IV, a stasis ulcer, a diabetic ulcer, a post-operative wound, a burn, an incision, abrasion, or a mild irritation. In some embodiments, the wound is periodically rinsed, washed, or immersed in the solution for at least two weeks, but the treatment may be periodically continued for about 4 weeks, about 9 weeks, or longer. In some embodiments, the wound is rinsed with the solution at least once per week, but may be treated with the solution at least twice per week, or more frequently.

Although the hypohalous acid solution may be delivered to the wound at room temperature, alternatively, the solution may be heated, for example, to or about body temperature. In such embodiments, the solution is comfortable and soothing for the patient, and more effective.

In some embodiments, the present invention provides methods of treating an infected or colonized wound, tissue, surgical cavity, or bone, and methods of reducing the bioburden of a wound. The treatment solutions according to the present invention described above are generally effective at killing or inactivating a broad spectrum of bacterial, fungal, and viral pathogens, including staphylococcus aureus, pseudomonas aeruginosa, escherichia coli, enterococcus, clostridium difficile, and candida. The solution does not produce resistant substances, making the method ideal compared to the delivery of traditional antibiotics.

In another aspect, the solutions of the invention are particularly suitable for use in combination with stem cell and growth factor therapies, including the use of genetically engineered cells and engineered tissues and allografts in various treatments and organs for transplantation. By using the stable hypohalous acid solution of the present invention to disinfect tissue before, during, or after addition of cells or growth factors, cell viability and growth factor integrity are maintained while unwanted microorganisms are killed.

In some embodiments, the solution or formulation thereof is administered for the control of inflammation, including inflammatory reactions or hyper-inflammation (hyper-inflammation) of the skin. For example, the solution or formulation thereof may be administered for use in the methods described in US2007/0196357 or US2010/0285151 (which are incorporated herein by reference). In some embodiments, a solution or composition of the invention is applied (e.g., to the affected area) for treating a patient suffering from a skin disorder, atopic dermatitis, skin allergies, rosacea, psoriasis, or acne, among others. In such embodiments, the HOCl solution may be formulated as a hydrogel, for example, as described elsewhere in this application.

In some embodiments, the present invention is advantageously used to combat microorganisms on surfaces because of the rapid activity against bacterial spores, fungi, and other resistant microorganisms. Because of its efficacy and speed of action, the present invention meets a number of public health needs, and needs that are not adequately addressed by currently available antimicrobial agents. Thus, application of the solution to various surfaces and materials can be used to control microbial contamination, not only for the care and treatment of wounds, but also for disinfecting hard surfaces such as medical or dental equipment, preserving and purifying food, water treatment, and other industrial and agricultural applications. In some embodiments, the solutions or compositions of the present invention are applied to crops (before or after harvesting) or cut flowers for their preservation and/or for improving the overall quality of the product. In some embodiments, the solution is potassium-based and has one or more of the utilities (e.g., methods of use) disclosed in PCT/US2011/43590, the entire contents of which are incorporated herein by reference.

In various embodiments, including treatment of food, agricultural products, and surfaces, the solution may be applied as a mist, spray, or ice.

Killing, inactivating, or otherwise reducing the active population of bacterial spores and fungi on a surface is particularly difficult. Bacterial spores have a unique spore coat chemical composition that makes them more resistant to the antimicrobial effects of chemical and physical agents than plant bacteria. Likewise, the unique chemical composition of fungal cells, particularly mold spores, makes them more resistant to chemical and physical agents than other microorganisms. Such resistance can be particularly troublesome when the spores or fungi are located on surfaces such as food, food contact sites, appliances, hospital and veterinary facilities, surgical instruments, and hospital and surgical bed wear and clothing.

Control of bacterial spore-forming microorganisms of the fungal chaff (Chaetomium funicola) and bacterial species may be particularly important during food packaging, particularly during cold or hot aseptic filling of food and beverage products. Microorganisms of the bacterial species include Bacillus cereus, Bacillus mycoides, Bacillus subtilis, Bacillus anthracis, and Bacillus thuringiensis. These latter microorganisms share many phenotypic properties, have a high level of chromosomal sequence similarity, and are known enterotoxin producers. Bacillus cereus is one of the most troublesome microorganisms because bacillus cereus has been identified as having increased resistance to bactericidal chemicals used to decontaminate environmental surfaces.

The term "surface" as used herein refers to both hard and soft surfaces and includes, but is not limited to, tile grout (tilegrout), stucco (mortar), drywall (drywall), ceramic, cement, clay, brick, decorative stucco (stucco), plastic, wallpaper, fabric, tile, mastic, and vinyl flooring, heating and/or cooling sheets, filters, vanes, grids, vents, cracks in walls or ceilings, paper and wood products such as wood, paper and cardboard, woven products such as blankets, clothing, carpets, cloth, and the like. The term surface also includes human surfaces, animal surfaces, military equipment, transportation equipment, juvenile products, plant surfaces, seeds, outdoor surfaces, soft surfaces, air, wounds, medical instruments, and the like.

Examples

Example 1: stabilized hypochlorous acid solution

Figures 1 and 2 show 5 cycles of AFC and pH measurements of hypochlorous acid wound treatment solutions over time at two ambient conditions-cold (C) and room temperature (R). As shown in the figure, pH and AFC content were not stable over time. For example, after more than about one week, the solution is unstable.

To stabilize the solution, hypochlorous acid is generated by: the electrochemical treatment contained 4.2g/L NaCl and 400mg/L NaHCO₃The electrolyte of (1). The sample was washed with sodium bicarbonate (NaHCO)₃) (pH5.6) and disodium phosphate (Na)₂HPO₄) Combined sodium bicarbonate (NaHCO)₃) (pH6.7), or sodium bicarbonate (NaHCO)₃) Mixture of disodium phosphate and sodium diphosphate (9 NaH)₂PO₄:1Na₂HPO₄) (pH5.6) buffering. The solution was stored in HDPE bottles for 1 month in the dark, and AFC was measured.

Fig. 3 shows the AFC degradation over time. The results show that when Na is reacted₂HPO₄Buffered (-25% loss) and 9NaH₂PO₄:1Na₂HPO₄The solution without phosphate buffer was significantly more stable (-8% loss) when compared to the buffered solution (-20% loss).

The stability of the stabilized solution was tested over time. Hypochlorous acid is generated by the following method: the electrochemical treatment contained 4.2g/L NaCl and 400mg/L NaHCO₃The electrolyte of (1). The solution had a pH of 5.3, a basicity of zero (0), and about 250ppm AFC. This solution was packaged in HDPE bottles and stored in the dark. The biocidal activity and stability over time of the solutions was tested by the following methods: the pH and AFC content in the closed test bottles was measured for more than 390 days. The results are shown in fig. 4, which shows that the AFC content and pH of the solution are stable for more than one year.

Generally, the NaOCl manufacturer envisages that a sodium hypochlorite solution loses about 20% of its titratable chlorine within the first 6 months and up to 60% within a year. One study assay, 25mg/mL sodium hypochlorite solution at 20 ℃ to reach 20mg/mL free residual chlorine would take 166 days based on stability at 50 ℃ and 70 ℃Studies and calculations using the Arrhenius Equation (see Nicoletti et al, "Shell-Life of a2.5% Sodium Hypochlorite solution as purified byArrhenius Equation," Braz Dent J (2009)20 (1): 27-31). Other studies have shown similar results (see "Product Characteristics, Sodium Hypochlority-Stability PCH-1400-. Contrary to these assumptions, the claimed NaHCO is₃The buffered hypochlorous acid solution retains greater than 75% of the initial level of titratable chlorine over a year, and a pH change of less than one unit.

Example 2: biocidal activity of stabilized HOCl solutions

Three solutions containing different concentrations of hypochlorous acid were prepared. The first solution (containing 250ppm hypochlorous acid) was prepared by: the electrochemical treatment contained 4.2g/L NaCl and 400mg/L NaHCO₃The electrolyte of (1). A second solution was similarly prepared by electrochemical treatment, containing 480ppm hypochlorous acid, but no NaHCO₃. The third solution contained 480ppm hypochlorous acid, but 1000mg/L NaHCO was additionally introduced₃。

To simulate the worst case, spores of clostridium difficile, a strain with high antibiotic resistance, were suspended in a highly concentrated organic medium consisting of homogenized skin cells from pigs, mucin, and bovine serum albumin. After suspending the microorganisms in the organic solution, they were seeded on plastic supports, dried and exposed to each solution in duplicate for 0, 4, 6, 8, 10 or 30 minutes. Since no existing disinfectant is able to withstand this organic load (including bleach), two different hypochlorous acid concentrations were tested.

The results (fig. 5) demonstrate that the solution with sodium bicarbonate possesses a higher biocidal activity against clostridium difficile spores under conditions of high organic load.

Example 3: extended stability study

FIG. 6 shows the results of a prolonged stability study of HOCl by electrochemical treatment of NaHCO at the target pH of 5.4₃The enriched NaCl solution was produced, bottled in polyethylene terephthalate (PET) containers and stored at room temperature. NaHCO in this formulation₃Is equal to 1 mole of NaHCO₃1 mol of HOCl. Every month (every second, 4 new samples of HOCl-stabilized solution were opened over the storage time, then opened again after one month, and tested once a week. Comparing the pH and AFC of the samples opened weekly during this month with the samples opened last confirms the stability of HOCl stabilized with sodium bicarbonate.

Example 4: stabilization of HOCl with added sodium bicarbonate

The stability of HOCl added to the vessel containing dry sodium bicarbonate is shown in fig. 7A and 7B. The ionic strength or solution salinity is not affected by the addition of sodium bicarbonate. The results demonstrate that bicarbonate as a stabilizer affects pH and AFC stability. Without being bound by any theory, the bicarbonate can act as a stabilizer, in part by scavenging free radicals generated by the decomposition of hypochlorous acid, at a pH of about 5.5 and with minimal buffering capacity of the bicarbonate. The result is a slight decrease in pH and AFC over time.

Example 5: stability of HOCl compositions for agricultural applications

The effect of DIC content on pH and solution stability in electrochemically generated hypochlorous acid solutions additionally buffered with sodium diphosphate and sodium monophosphate for a target pH (which has utility for agricultural applications) is shown in fig. 8. Compositions of hypochlorous acid with phosphate additives were tested with and without bicarbonate. The results show that hypochlorous acid has better stability in the presence of bicarbonate compared to phosphate alone. The combination of DIC and phosphate buffer provides better solution stability without significantly increasing the total dissolved solids content.

Example 6: hydrogel formulations

Hydrogel formulations containing stable hypochlorous acid solutions were prepared. The use of bicarbonate or dissolved inorganic carbon according to the invention has only a minor effect on the ionic strength or conductivity of the solution. Thus, in addition to stabilizing the HOCl solution at a pH range of about 4 to about 7.5 (e.g., about 6.0), the bicarbonate or carbonate salt does not affect ionic strength at the target pH, thereby allowing the use of hypochlorous acid with more than 200ppm available free chlorine as a dispersion medium in gel formulations, especially where low ionic strength is critical to the formulation.

A low ionic strength hypochlorous acid solution (conductivity ≦ 1mS/cm (i.e., millisiemens/cm)) with AFC =300ppm, ph5.3 was used for the hydrogel formulation containing 3% magnesium sodium fluorosilicate. To prepare hydrogels of equal viscosity made from 8mS/cmHOCl with equal pH and AFC content, more than 4% sodium magnesium fluorosilicate was required. The lower ionic strength HOCl solution as a dispersion medium allows the addition of other buffers in the final product for pH optimization without negatively impacting physical appearance and product stability. Since the gelling agent is the dry buffer itself, the ability to add other buffers in the final product for pH optimization may be beneficial.

In another example, a hypochlorous acid solution having AFC350ppm, pH5.3, salinity of 4g/l (conductivity 8mS/cm) was used to prepare a solution containing 4% F₁₂MgNa₂Si₂(magnesium sodium fluorosilicate) hydrogel. The resulting hydrogel had a viscosity of 330 centipoise (cP) and a pH of 8.2. To bring the pH into the "skin friendly" range, phosphoric acid was added as a buffer. The final hydrogel pH change over time was from pH6 to 6.8, as shown in figure 9. Additional buffers are limited by the viscosity of the gelThe conductivity increased to 10mS/cm as the viscosity changed to 220 cP.

Low ionic strength hypochlorous acid of AFC =370ppm was produced by electrochemical treatment of sodium chloride, substantially as described in U.S. patent No. 7,897,023 (incorporated herein by reference in its entirety), and collected in a container with dry sodium bicarbonate equal to 500ppm NaHCO as the original form of Dissolved Inorganic Carbon (DIC)₃. HOCl produced by this method at pH5.2 and conductivity 0.8mS/cm is the dispersion medium for the gum formulation and is used as the dispersion medium for the gel formulation. 3% sodium magnesium fluorosilicate was used as the gelling agent. A hydrogel having a viscosity of about 10,000cP with an initial pH of 8.4 and a conductivity of about 1mS/cm was formed in less than 25 minutes. Phosphoric acid is added in an amount of less than 0.25% to lower the pH of the hydrogel to the skin friendly range (about pH 5.5-5.8). A hydrogel with a viscosity above 2,000cP is formed.

All references cited in this application are incorporated herein by reference in their entirety.

Claims (19)

1. A stable solution or formulation in a container comprising hypochlorous acid and a stable amount of dissolved inorganic carbon in the form of sodium bicarbonate,

wherein the solution or formulation has a free available chlorine content of 100ppm to 500ppm, a pH of 5 to 7, and sodium bicarbonate in a molar ratio of 300mg/L to 1500mg/L, wherein the molar ratio of sodium bicarbonate to free available chlorine is 5:1 to 1:5,

wherein said available free chlorine content and said pH are stable for at least 1 month,

and wherein saidContainer pair CO₂Or O₂Has a slight permeability.

2. The stable solution or formulation of claim 1, wherein the available free chlorine content and the pH are stable for at least 6 months.

3. The stable solution or formulation of claim 1, wherein the available free chlorine content is from 150ppm to 250 ppm.

4. The stable solution or formulation of claim 1, wherein the pH is from 5.4 to 6.4 or from 5.0 to 6.4.

5. The stable solution or formulation of claim 1, wherein the molar ratio of sodium bicarbonate to available free chlorine is at least 1: 2.

6. The stable solution or formulation of claim 5 wherein the amount of sodium bicarbonate is equimolar to the available free chlorine content.

7. The stable solution or formulation of any one of claims 1 to 6, wherein the hypochlorous acid is prepared by electrolysis of a NaCl solution.

8. The stable solution or formulation of claim 7, wherein sodium bicarbonate is contained in the NaCl electrolyte.

9. The stable solution or formulation of claim 7, wherein the sodium bicarbonate is added after electrolysis.

10. The stable solution or formulation of any one of claims 1-6 and 8-9, wherein the container is a bottle, a bag, a tube, or a can.

11. The stable solution or formulation of claim 10, wherein the container is a bottle.

12. The stable solution or formulation of claim 10, wherein the container is opaque.

13. A method of preparing the stable solution or formulation of any one of the preceding claims, comprising:

introducing the dissolved inorganic carbon in the form of sodium bicarbonate into the solution or formulation in an amount sufficient to stabilize the solution or formulation for at least six months.

14. The method of claim 13, wherein the sodium bicarbonate is added to the electrolyzed solution.

15. A method of disinfecting or cleaning a hard surface comprising applying the stable solution or formulation of any one of claims 1-12 to the hard surface.

16. The method of claim 15, wherein said hard surface comprises porcelain, steel, plastic, children's supplies, and medical instruments.

17. The method of claim 15, wherein the hard surface comprises a ceramic material.

18. A method of treating a food product comprising applying the stable solution or formulation of any one of claims 1-12 to the food product.

19. The method of claim 18, wherein the solution is applied as a mist, fog, spray, or ice.