Antibacterial complex, antibacterial complex solution, antibacterial composition, and method for producing the same

Abstract

To provide an antibacterial composite that can be suitably used as an effective ingredient of an antibacterial composition that has small environmental influence with a copper content less than a conventional copper agent and with a small amount of application, and can obtain antibacterial effect same as before or more than ever, and particularly suitable for agricultural usage, as well as, can be applied to various usages other than the agricultural usage.SOLUTION: An antibacterial composite of the present invention comprises a carrier that is a nanostructure made of a biopolymer, a metal or metal oxide that is a nanoparticle supported on the carrier, and an adjuvant having multiple positive charges, wherein a mass ratio of the content of the adjuvant to the content of the carrier [(adjuvant) / (carrier)] is 0.01 or more and 15 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an antibacterial complex, an antibacterial complex solution, an antibacterial composition, and a method for producing the same. [Background technology]

[0002] Inorganic copper pesticides have been known to be suitable for organic farming. For example, Bordeaux mixture, a mixed solution of copper sulfate and calcium hydroxide, is used on a wide range of crops, including fruit trees and vegetables, due to its excellent preventative effect against a wide range of diseases, its long-lasting efficacy, and its low cost.

[0003] On the other hand, with the recent spread of organic farming, the use of inorganic copper agents has increased, and contamination due to copper accumulation in the soil is becoming a problem. Furthermore, the copper sulfate contained in the Bordeaux mixture mentioned above is highly toxic to aquatic organisms, so it is necessary to prevent its inflow into rivers and other streams. Furthermore, because copper sulfate causes copper damage to leaves and fruits, formulations containing copper sulfate have limited application periods. Therefore, it is desirable to achieve the same effect as conventional formulations with a lower copper content.

[0004] In an attempt to treat target crops with a copper-containing formulation at a smaller application rate, Patent Document 1 proposes "a method for controlling plant pathogenic microorganisms by treating with an effective amount of copper salt particles containing a water-soluble polymer and having a primary particle size of 1 to 200 nm, wherein the copper salt forms a precipitate with copper ions and contains an anion that is not hydroxide." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2013-512870 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention aims to provide an antibacterial composition that is particularly suitable for agricultural use, which has a lower copper content or application rate than conventional copper agents, has a smaller impact on the environment, and provides antibacterial effects that are equal to or superior to conventional copper agents. Another object of the present invention is to provide an antibacterial composition that can be used in industrial applications other than agriculture, such as medical care, nursing care, livestock and fisheries, and food, as well as for general use, by using a metal with a certain antibacterial activity (e.g., copper, silver, gold, platinum, zinc, cobalt, nickel, palladium, aluminum, and combinations thereof, etc.) as the type of metal contained in the antibacterial composition, or by incorporating a metal oxide (e.g., titanium oxide, zinc oxide, iron oxide, tungsten oxide, strontium titanate, zirconium oxide, and combinations thereof, which are compounds that have antibacterial activity due to a photocatalytic reaction). Another object of the present invention is to provide an antibacterial complex and an antibacterial complex solution suitable for use as the active ingredient of the above antibacterial composition. [Means for solving the problem]

[0007] The antibacterial complex of the present invention contains a carrier that is a nanostructure made of a biopolymer, a metal or metal oxide nanoparticle supported on the carrier, and an auxiliary agent having a polyvalent positive charge, and the mass ratio of the content of the auxiliary agent to the content of the carrier [(auxiliary agent) / (carrier)] is 0.01 or more and 15 or less, thereby solving the above-mentioned problem. The mass ratio of the content of the auxiliary agent to the content of the metal or metal oxide [(auxiliary agent) / (metal·metal oxide)] may be 0.3 or more and 200 or less. The mass ratio of the content of the metal or metal oxide to the content of the support [(metal·metal oxide) / (support)] may be 0.02 or more and 0.5 or less.

[0008] In the antibacterial complex, the mass ratio of the content of the auxiliary to the content of the carrier [(auxiliary) / (carrier)] may be 0.02 or more and 15 or less, the mass ratio of the content of the auxiliary to the content of the metal or metal oxide [(auxiliary) / (metal·metal oxide)] may be 0.5 or more and 200 or less, the mass ratio of the content of the metal or metal oxide to the content of the carrier [(metal·metal oxide) / (carrier)] may be 0.04 or more and 0.5 or less, and the minimum inhibitory concentration (MIC) value of Escherichia coli and / or Staphylococcus aureus converted into the content of the metal or metal oxide, measured by a microbial metabolic activity measurement method based on a water-soluble tetrazolium salt reduction reaction, may be 0.8 or less as a ratio to the MIC value measured for a reference sample.

[0009] In the antibacterial composite, the particle size of the metal or metal oxide may be 1 nm or more and 250 nm or less. The metal may also be selected from the group consisting of copper, silver, gold, platinum, zinc, cobalt, nickel, palladium, aluminum, and combinations thereof. The metal oxide may also be selected from the group consisting of titanium oxide, zinc oxide, iron oxide, tungsten oxide, strontium titanate, zirconium oxide, and combinations thereof. The biopolymer may also be selected from the group consisting of cellulose, chitosan, chitin, silk, gelatin, collagen, alginic acid, starch, and combinations thereof. The carrier may also be a nanofiber. The adjuvant may also be a magnesium salt, a calcium salt, or a combination thereof, or a quaternary ammonium salt.

[0010] The antibacterial complex solution of the present invention contains the above antibacterial complex and an optional solvent, thereby solving the above problems.

[0011] In the above antibacterial complex solution, the carrier may be a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof, the metal or metal oxide may be copper nanoparticles, the auxiliary agent may be a magnesium salt, a calcium salt, or a combination thereof, the mass ratio of the content of the auxiliary agent to the content of the carrier [(auxiliary agent) / (carrier)] may be 0.5 or more and 5 or less, the mass ratio of the content of the auxiliary agent to the content of the metal or metal oxide [(auxiliary agent) / (metal·metal oxide)] may be 5 or more and 50 or less, and the mass ratio of the content of the metal or metal oxide to the content of the carrier [(metal·metal oxide) / (carrier)] may be 0.03 or more and 0.25 or less.

[0012] Furthermore, in the above antibacterial complex solution, the carrier may be a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof, the metal or metal oxide may be copper nanoparticles, the auxiliary agent may be a quaternary ammonium salt, the mass ratio of the content of the auxiliary agent to the content of the carrier [(auxiliary agent) / (carrier)] may be 0.1 or more and 12.5 or less, the mass ratio of the content of the auxiliary agent to the content of the metal or metal oxide [(auxiliary agent) / (metal·metal oxide)] may be 0.5 or more and 85 or less, and the mass ratio of the content of the metal or metal oxide to the content of the carrier [(metal·metal oxide) / (carrier)] may be 0.03 or more and 0.25 or less.

[0013] Furthermore, in the above antibacterial complex solution, the carrier may be a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof, the metal or metal oxide may be silver nanoparticles, the auxiliary agent may be a quaternary ammonium salt, the mass ratio of the content of the auxiliary agent to the content of the carrier [(auxiliary agent) / (carrier)] may be 0.3 or more and 5 or less, the mass ratio of the content of the auxiliary agent to the content of the metal or metal oxide [(auxiliary agent) / (metal·metal oxide)] may be 5 or more and 200 or less, and the mass ratio of the content of the metal or metal oxide to the content of the carrier [(metal·metal oxide) / (carrier)] may be 0.02 or more and 0.1 or less.

[0014] The antibacterial composition of the present invention contains the above antibacterial complex or the above antibacterial complex solution, thereby solving the above problems.

[0015] The antibacterial composition for agricultural use of the present invention contains the above antibacterial complex solution, thereby solving the above problems.

[0016] The method for producing the antibacterial complex solution of the present invention includes preparing a carrier solution containing the carrier, adding a dispersion of metal nanoparticles to the carrier solution and stirring and mixing, and adding the auxiliary agent to the resulting mixture and further stirring and mixing. [Effects of the Invention]

[0017] According to the present invention, there is provided an antibacterial composite that has a lower copper content or application rate than conventional copper agents, has less impact on the environment, and provides antibacterial effects equivalent to or superior to conventional copper agents, and is suitable for use as an active ingredient in antibacterial compositions particularly suitable for agricultural applications, as well as for antibacterial compositions that can be used for various applications other than agricultural applications. In other words, the antibacterial composite of the present invention can be used in a variety of applications, including agriculture, by preparing an antibacterial composition from a solution containing the antibacterial composite as is, or by diluting it with an optional diluent. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a flow chart illustrating an exemplary method for making the antimicrobial complex solution of the present invention. [Figure 2] FIG. 1 shows the results of plotting the mass ratio [(adjuvant) / (metal)] value and the MIC value (Cu ppm) against Escherichia coli or the MIC value (Cu ppm) against Staphylococcus aureus on a double logarithmic graph for the test solution used in Test Example 4 of the Examples. [Figure 3] FIG. 1 shows the results of plotting the mass ratio [(adjuvant) / (metal)] value versus the MIC value (BzCl ppm) against Escherichia coli or the MIC value (BzCl ppm) against Staphylococcus aureus on a double logarithmic graph for the test solution used in Test Example 4 of the Examples. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail.

[0020] [Antimicrobial Composite] The antibacterial composite of the present invention (hereinafter also referred to simply as "composite") contains a carrier which is a nanostructure made of a biopolymer, a metal or metal oxide nanoparticle supported on the carrier, and an auxiliary agent having a polyvalent positive charge. In the present invention, "containing the carrier, the metal or metal oxide, and the auxiliary" also means that the carrier, the metal or metal oxide, and the auxiliary are blended together.

[0021] [Support] In this specification, the term "support" refers to a substance that serves as a base for immobilizing a metal or metal oxide, which will be described later. That is, in the present invention, the support is a supporting body that supports a metal or metal oxide.

[0022] The carrier is a nanostructure. Examples of nanostructures include, but are not limited to, nanoparticles, nanofibers, nanowires, nanorods, nanotubes, and nanofilms. The carrier used in the present invention may have one or more types of structure (shape).

[0023] As used herein, the term "nanostructure" refers to a structure in which at least one of the size indicators (length, width, diameter, etc.) commonly used depending on the shape of the structure is on the nano-order (in the range of 1 nm to 1000 nm). For example, in the case of nanoparticles, the mean diameter of the particles (particulate material) (hereinafter also simply referred to as "particle size") is intended to be in the range of 1 nm to 1000 nm. In addition, in the case of nanofibers, the mean diameter of the fibers (fibrous material) is intended to be in the range of 1 nm to 1000 nm. In a narrower sense, nanofibers refer to fibrous material having a diameter in the range of 1 nm to 100 nm and a length 100 times or more the diameter.

[0024] As used herein, the "biopolymer" constituting the carrier refers to a natural polymer produced by the cells of an organism, and is also called a biopolymer. Generally, biopolymers are classified into three major classes, namely, polynucleotides, polypeptides, and polysaccharides, depending on the monomers, which are the repeating units constituting the molecule, and the structure of the biopolymer. In the present invention, any biopolymer classified into these three classes can be used as a carrier.

[0025] Specifically, the biopolymer is preferably selected from the group consisting of cellulose, chitosan, chitin, silk, gelatin, collagen, starch, and alginic acid. Among these, biopolymers classified as polysaccharides include cellulose, which constitutes plants; chitin, which is the main component of the shells of crabs, shrimp, and beetles; and chitosan obtained from chitin. These biopolymers are naturally abundant, biodegradable, and therefore considered to have little impact on the environment, and are therefore suitable for use as a carrier.

[0026] [Metal or Metal Oxide: Metal / Metal Oxide] The nanoparticles of the metal or metal oxide are supported on the carrier. In other words, in the antibacterial composite of the present invention, the nanoparticles of the metal or metal oxide are fixed to the biopolymer constituting the carrier. The fixing method is not particularly limited, but examples thereof include adsorption by physical interaction such as electrostatic interaction or chemical interaction (formation of chemical bonds such as covalent bond, ionic bond, metallic bond, coordinate bond, etc.).

[0027] As used herein, the term "nanoparticles" used in reference to metals or metal oxides refers to fine particles with a particle size ranging from 1 nm to 1000 nm. The particle size of nanoparticles is measured using a dynamic light scattering (DLS) method using a laser light source. Specifically, the particle size of the fine particles is measured using a method in accordance with ISO 22412:2017, in which laser light is irradiated onto the fine particles dispersed in a solution, and the scattered light is observed with a photon detector.

[0028] The particle size of the metal or metal oxide nanoparticles used in the present invention is not particularly limited. However, a smaller particle size allows a larger number of metal or metal oxide particles to be supported on a given area of ​​the carrier, allowing a wider surface area of ​​these particles to come into contact with the target object. Therefore, in the case of copper nanoparticles, for example, the antibacterial properties of the metal nanoparticles are expected to be more effectively exerted, such as by facilitating the generation of reactive oxygen, which is thought to be one of the mechanisms of the antibacterial action of metallic copper, and the elution of copper (II) ions from the metallic copper surface. Furthermore, in the case of metal oxide nanoparticles, light can be absorbed over a wider area of ​​the particle surface, allowing for more effective antibacterial action via photocatalytic reactions. Specifically, the particle size of the metal or metal oxide nanoparticles may be 1 nm to 250 nm, 1 nm to 200 nm, 1 nm to 150 nm, or 1 nm to 100 nm.

[0029] The type of metal constituting the metal nanoparticles is not particularly limited as long as it has a certain level of antibacterial properties. In other words, since it has been known that certain types of metals have a certain level of antibacterial (or bactericidal) activity, any metal can be selected depending on the intended use and the target object. For example, in the case of agricultural applications, metals that are known or expected to have antibacterial activity against bacteria that cause diseases (plant pathogenic bacteria) that may occur in the target crops can be used. Furthermore, the metal may be of one type, or multiple types may be combined. However, it is preferable to select metals taking into consideration the impact on humans, livestock, and the environment.

[0030] Specifically, metals that can be preferably used in the present invention include, but are not limited to, copper, silver, gold, platinum, zinc, cobalt, nickel, palladium, aluminum, and combinations thereof.

[0031] The type of metal oxide constituting the metal oxide nanoparticles is not particularly limited as long as it has a certain level of antibacterial properties. For example, since it has been known that certain types of metal oxides have antibacterial properties due to photocatalytic reactions, any metal oxide can be selected depending on the intended use and the target object. Of course, the mechanism of the antibacterial action of the metal oxide may be something other than photocatalytic reactions. Furthermore, the metal oxide may be one type or a combination of multiple types. However, it is preferable to select a metal oxide taking into consideration its impact on humans, animals, and the environment.

[0032] Specifically, metal oxides that can be preferably used in the present invention include, but are not limited to, titanium oxide, zinc oxide, iron oxide, tungsten oxide, strontium titanate, zirconium oxide, and combinations thereof. Note that all of the metal oxides listed above are compounds that have antibacterial activity due to a photocatalytic reaction.

[0033] The viable bacteria count (also known as general viable bacteria count) can be used as a standard for evaluating the antibacterial properties of metals or metal oxides. This is one of the hygiene indicator bacteria (contamination indicator bacteria) used to evaluate the hygienic quality of food, and is measured by measuring the number of bacteria that grow on an agar medium under certain temperature and nutritional conditions. The bacteria measured here include E. coli, coliform bacteria, Staphylococcus aureus, and Salmonella.

[0034] Furthermore, the JIS standard for the antibacterial properties of antibacterial processed metal products targets Escherichia coli and Staphylococcus aureus for evaluation. Therefore, when evaluating the antibacterial properties of the antibacterial complex of the present invention, tests using Escherichia coli and / or Staphylococcus aureus can be employed. The examples described below will describe test examples in which the antibacterial properties of an antibacterial complex solution and an antibacterial composition containing the antibacterial complex of the present invention were evaluated by tests using these bacteria.

[0035] [Auxiliary Agent] As used herein, the term "adjuvant" refers to a substance contained in a composite for the purpose of facilitating the formation of a structure in which a metal or metal oxide is supported on a carrier and / or facilitating the maintenance of that structure, and / or for the purpose of maintaining or enhancing the antibacterial properties of the composite. In other words, an adjuvant can generally mean at least one or both of a substance (adjuvant) that maintains or enhances the efficacy of the active ingredient of a pesticide or other agent or that facilitates application (use), and a substance (additive) that is added for these purposes during production or formulation.

[0036] The adjuvant is a substance having a polyvalent positive charge. The polyvalent positive charge of the adjuvant facilitates the formation of a structure in which a metal or metal oxide is supported on a carrier, and / or facilitates the maintenance of this structure. This allows the antibacterial properties of the complex to be effectively maintained. Additionally, when the adjuvant itself has antibacterial and bactericidal properties, the antibacterial properties of the complex can be enhanced. Specific examples of adjuvants include, but are not limited to, magnesium salts, calcium salts, and quaternary ammonium salts.

[0037] Magnesium salts and calcium salts each ionize in aqueous solution to form magnesium ions (Mg 2+ ) and calcium ions (Ca 2+ ) are all known to be polyvalent cations that are abundant in the environment.

[0038] Examples of magnesium salts include magnesium chloride, magnesium hydroxide, magnesium carbonate, magnesium sulfate, magnesium oxide, magnesium L-glutamate, magnesium stearate, and trimagnesium phosphate. Examples of calcium salts include calcium chloride, calcium oxide, calcium citrate, calcium hydroxide, calcium carbonate, calcium lactate, and calcium sulfate. Both the magnesium salts and calcium salts mentioned above are substances that can be used as food additives, and are therefore preferred from the viewpoint of safety.

[0039] Quaternary ammonium salts also exist in nature and are known to exist in biological compounds such as acetylcholine chloride, trimethylglycine, and L-carnitine. Many compounds have been synthesized as quaternary ammonium salts, and various applications have been reported.

[0040] Among these, benzalkonium chloride and benzethonium chloride are known to have antibacterial properties and are used as low-level disinfectants, making them suitable for use as adjuvants in the present invention. Furthermore, cetylpyridinium chloride is a bactericidal ingredient used in toothpastes, mouthwashes, mouthwashes, etc., and can therefore be used as an adjuvant in the present invention. When the antibacterial complex of the present invention contains these quaternary ammonium salts, it is expected that the antibacterial and bactericidal effects of the quaternary ammonium salt and the antibacterial effects of the metal or metal oxide will act additively or synergistically. Specifically, for example, when the antibacterial complex of the present invention contains copper nanoparticles as the metal or metal oxide and benzalkonium chloride as an adjuvant, it is expected that the immediate antibacterial activity of benzalkonium chloride and the delayed antibacterial activity due to the elution of copper(II) ions from the surface of the metallic copper and the generation of active oxygen will act on the target object in a two-stage combination or multiplication of these effects. In other words, by considering the type of metal or metal oxide pre-selected depending on the purpose of use, target object, etc., and then selecting the auxiliary agent to be combined with it, a composite can be obtained that more efficiently exhibits the desired antibacterial effect.

[0041] [Content ratio of each component] Next, the content ratio of each component contained in the antibacterial composite of the present invention, specifically the mass ratio of the content of the carrier, metal or metal oxide, and auxiliary agent, will be described.

[0042] The mass ratio of the content of the auxiliary to the content of the carrier [(auxiliary) / (carrier)] is preferably 0.01 or more and 15 or less. This more reliably maintains the structure in which the carrier supports the metal or metal oxide. In other words, when the mass ratio of the auxiliary to the carrier is adjusted to fall within the above range during the production of the composite, the structure in which the carrier supports the metal or metal oxide is easily formed. It is believed that this effect is essentially influenced by the relationship between the number of carrier molecules and the number of auxiliary molecules (or the number of ions, if ionized) contained in the composite. However, it is not practical to analyze this relationship for all possible combinations of carrier and auxiliary in the antibacterial composite of the present invention and derive a consistent index. Therefore, in the present invention, the mass ratio is used as an index instead of the relationship between the number of molecules (number of ions). The same applies to the mass ratio [(auxiliary) / (metal / metal oxide)] and the mass ratio [(metal / metal oxide) / (carrier)] described below.

[0043] This mass ratio [(auxiliary agent) / (carrier)] can be adjusted depending on the type of auxiliary agent used. For example, when the auxiliary agent is a magnesium salt, a calcium salt, or a combination thereof, the mass ratio may be 0.05 to 15, 0.05 to 10, 0.1 to 10, 0.1 to 5, or 0.5 to 5. When the auxiliary agent is a quaternary ammonium salt, the mass ratio may be 0.025 to 15, 0.05 to 15, 0.05 to 12.5, 0.1 to 12.5, 0.1 to 10, 0.1 to 5, or 0.1 to 2.5.

[0044] The mass ratio of the content of the auxiliary to the content of the metal or metal oxide [(auxiliary) / (metal·metal oxide)] is preferably 0.3 or more and 200 or less. This more reliably maintains the structure in which the metal or metal oxide is supported on the carrier, and the antibacterial properties of the composite are more efficiently exhibited. In other words, when the mass ratio of the auxiliary to the metal or metal oxide is blended within the above range during the production of the composite, the structure in which the metal or metal oxide is supported on the carrier is more easily formed and this structure is more reliably maintained, so that the antibacterial properties of the metal or metal oxide contained in the composite are more efficiently exhibited.

[0045] This mass ratio [(auxiliary agent) / (metal / metal oxide)] can be adjusted depending on the type of auxiliary agent used. For example, when the auxiliary agent is a magnesium salt, a calcium salt, or a combination thereof, the mass ratio may be 0.45 to 150, 0.5 to 100, 1 to 100, 5 to 75, 5 to 50, 5 to 45, or 5 to 40. When the auxiliary agent is a quaternary ammonium salt, the mass ratio may be 0.3 to 150, 0.3 to 100, 0.5 to 85, 0.5 to 50, 0.5 to 25, or 0.5 to 10. In particular, in the latter case, the antibacterial and germicidal effects of the quaternary ammonium salt and the antibacterial effects of the metal or metal oxide are expected to act additively or synergistically, while a low content of the quaternary ammonium salt may be desirable depending on the intended use and the target substance, and therefore the mass ratio may be a relatively small value (for example, 25 or less, or 10 or less).In contrast, in the former case, even if the content of the magnesium salt and / or calcium salt is high and the mass ratio is relatively high, the impact on humans, animals, and the environment is not thought to be significant, but from the standpoint of production efficiency and production costs, it is preferable to reduce the content of the magnesium salt and / or calcium salt and set the mass ratio to 50 or less.

[0046] The mass ratio of the content of the metal or metal oxide to the content of the carrier [(metal·metal oxide) / (carrier)] is preferably 0.02 or more and 0.5 or less. This allows the structure in which the metal or metal oxide contained in the composite is supported on the carrier to exhibit enhanced antibacterial properties against the target object. In other words, for example, when the content of the metal or metal oxide is high and the mass ratio is large, the antibacterial properties of the metal or metal oxide are theoretically likely to be exhibited, but adhesion to the target object may be reduced, resulting in a decreased residual effect. On the other hand, when the content of the metal or metal oxide is low and the mass ratio is small, adhesion to the target object may be improved due to the properties of the biopolymer constituting the carrier, but antibacterial properties may be reduced due to the small number of metal or metal oxides supported on the carrier. In this regard, when the mass ratio [(metal·metal oxide) / (carrier)] is within the above range, a composite can exhibit the desired antibacterial properties, exhibit good adhesion to the target object, and have sufficient residual effect.

[0047] From this viewpoint, the mass ratio [(metal / metal oxide) / (support)] can be adjusted depending on the types of metal or metal oxide and support used, and further, the type of auxiliary agent used may also be taken into consideration.

[0048] For example, in one embodiment where the metal or metal oxide is copper nanoparticles, the mass ratio may be 0.03 or more and 0.25 or less. In this embodiment, the carrier may be, for example, a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof. Furthermore, the adjuvant may be a magnesium salt, a calcium salt, or a combination thereof.

[0049] In another embodiment in which the metal or metal oxide is copper nanoparticles, the mass ratio may be 0.03 or more and 0.25 or less. In this embodiment, the carrier may be, for example, a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof. Furthermore, the adjuvant may be a quaternary ammonium salt.

[0050] In another embodiment in which the metal or metal oxide is silver nanoparticles, the mass ratio may be 0.02 or more and 0.1 or less. In this embodiment, the carrier may be, for example, a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof. Furthermore, the adjuvant may be a quaternary ammonium salt.

[0051] Here, with respect to the three types of mass ratios described above, in an exemplary preferred embodiment, the following conditions are satisfied: The mass ratio [(auxiliary agent) / (carrier)] is 0.02 or more and 15 or less, the mass ratio [(auxiliary agent) / (metal / metal oxide)] is 0.5 or more and 200 or less, The mass ratio [(metal / metal oxide) / (support)] is 0.04 or more and 0.5 or less. Furthermore, the antibacterial complex according to this embodiment has a lower minimal inhibitory concentration (MIC) value for Escherichia coli and / or Staphylococcus aureus, calculated as the metal or metal oxide content, than a reference sample, as measured by a microbial metabolic activity measurement method based on the reduction reaction of a water-soluble tetrazolium salt.

[0052] Here, the term "reference sample" refers to a sample that does not satisfy the above three mass ratio conditions and is close to the lower or upper limits of these ranges, but is prepared using carriers, metals or metal oxides, and auxiliary agents that are substantially the same as those contained in the antibacterial composite of the present embodiment. In other words, a reference sample is a sample used as a standard for evaluating the antibacterial properties of the antibacterial composite of the present invention. For example, if an existing agent, such as the inorganic copper agent described above, exists, the antibacterial properties of the antibacterial composite of the present invention can be evaluated by comparing it with the existing agent. However, if such an agent does not exist, or depending on the type of metal or metal oxide or auxiliary agent used, it may not be appropriate to evaluate the antibacterial properties of the antibacterial composite of the present invention by comparing it with the existing agent. Considering these circumstances, the significance of using the reference sample should be understood. Furthermore, those skilled in the art can appropriately determine the conditions for preparing such a reference sample.

[0053] The antibacterial properties of the antibacterial composite according to the present embodiment and the reference sample can be evaluated using the minimum inhibitory concentration (MIC) of Escherichia coli and / or Staphylococcus aureus, calculated as the metal or metal oxide content, measured by a microbial metabolic activity measurement method based on the water-soluble tetrazolium salt reduction reaction. An example of a specific procedure for this microbial metabolic activity measurement method is described in Test Example 4 in the Examples section below (see, Japanese Journal of Food Chemistry, Vol. 62, No. 7, pp. 321-327, 2015). Here, the MIC value obtained by the antibacterial composite according to the present embodiment is lower than the MIC value of the reference sample when the ratio of the MIC values ​​(composite according to the present embodiment / reference sample) is less than 1. This ratio is preferably 0.8 or less, more preferably 0.75 or less. In particular, in embodiments in which the adjuvant is a quaternary ammonium salt, the antibacterial and germicidal effects of the quaternary ammonium salt and the antibacterial effect of the metal or metal oxide act additively or synergistically, resulting in the complex of this embodiment exhibiting high antibacterial activity, and the above ratio may be 0.5 or less, 0.25 or less, 0.125 or less, or less than 0.1.

[0054] [Antibacterial complex solution] The antibacterial complex of the present invention may also be provided as an antibacterial complex solution in a state where it is mixed with an optional solvent. That is, the antibacterial complex solution of the present invention contains the above-mentioned antibacterial complex and an optional solvent. In the present invention, "containing the antibacterial complex and the optional solvent" also means that the antibacterial complex is a mixture of the carrier, the metal or metal oxide, the auxiliary agent, and the optional solvent.

[0055] The type of solvent is not particularly limited and can be appropriately selected depending on the application of the solution, the target object, etc. For example, in a typical embodiment, the solvent is water. In another embodiment, the solvent may be water, alcohols (e.g., methanol, ethanol, etc.), or a mixture thereof.

[0056] Here, with regard to the content ratios of each component of the complex (carrier, metal or metal oxide, and auxiliary agent) contained in the antibacterial complex solution of the present invention, the following are examples of more specific embodiments of the three types of mass ratios mentioned above.

[0057] <Embodiment L1> The mass ratio [(auxiliary agent) / (carrier)] is 0.5 or more and 5 or less, the mass ratio [(auxiliary agent) / (metal / metal oxide)] is 5 or more and 50 or less, The mass ratio [(metal / metal oxide) / (support)] is 0.03 or more and 0.25 or less. Here, the carrier may be a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof. The metal or metal oxide may also be copper nanoparticles. The adjuvant may also be a magnesium salt, a calcium salt, or a combination thereof.

[0058] <Embodiment L2> The mass ratio [(auxiliary agent) / (carrier)] is 0.1 or more and 12.5 or less, the mass ratio [(auxiliary agent) / (metal / metal oxide)] is 0.5 or more and 85 or less, The mass ratio [(metal / metal oxide) / (support)] is 0.03 or more and 0.25 or less. Here, the carrier may be a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof. The metal or metal oxide may also be copper nanoparticles. The adjuvant may also be a quaternary ammonium salt.

[0059] <Embodiment L3> The mass ratio [(auxiliary agent) / (carrier)] is 0.3 or more and 5 or less, the mass ratio [(auxiliary agent) / (metal / metal oxide)] is 5 or more and 200 or less, The mass ratio [(metal / metal oxide) / (support)] is 0.02 or more and 0.1 or less. Here, the carrier may be a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof. The metal or metal oxide may also be silver nanoparticles. The adjuvant may also be a quaternary ammonium salt.

[0060] In embodiment L1, the metal or metal oxide is copper nanoparticles, and the adjuvant is magnesium salt, calcium salt, or a combination thereof, making it suitable for agricultural applications. In addition to agricultural applications, it is also suitable for applications where minimal impact on humans and animals (high safety) and reduced environmental impact are important. In embodiment L2, the metal or metal oxide is copper nanoparticles and the auxiliary agent is a quaternary ammonium salt, making it suitable for use in applications where it is important to ensure antibacterial properties against common bacteria, etc. (e.g., medical care, nursing care, etc.). In embodiment L3, the metal or metal oxide is silver nanoparticles and the auxiliary agent is a quaternary ammonium salt, and similar to embodiment L2, it can be suitably used in applications where it is important to obtain antibacterial properties against common bacteria more reliably (e.g., medical care, nursing care, etc.). In addition, in any of the embodiments L1 to L3, by using a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof as the carrier, an antibacterial complex solution containing a complex with good adhesion to the target object and sufficient residual effect can be obtained. Furthermore, when the mass ratio [(metal / metal oxide) / (carrier)] is 0.04 or more, an antibacterial complex solution with excellent adhesion to the target object and residual effect can be obtained.

[0061] It should be noted that the above-mentioned combinations of metals or metal oxides, adjuvants, and carriers are merely examples, and that other combinations may also be used to obtain an antibacterial complex solution suitable for the intended use.

[0062] [Method for producing antibacterial complex solution] Next, a method for producing the antibacterial complex solution of the present invention will be described.

[0063] FIG. 1 is a flow chart illustrating an exemplary method for making the antimicrobial complex solution of the present invention.

[0064] Step S110: A carrier solution containing a carrier is prepared. The solvent for the carrier solution is not particularly limited. As with the solvent for the antibacterial complex solution of the present invention described above, it may be appropriately selected depending on the application of the solution, the target substance, etc. For example, in a typical embodiment, the solvent for the carrier solution is water. In another embodiment, the solvent for the carrier solution may be water, alcohols (e.g., methanol, ethanol, etc.), or a mixture thereof.

[0065] Step S120: The dispersion of metal nanoparticles or metal oxide nanoparticles is added to the carrier solution obtained in step S110 and mixed by stirring. The solvent for the dispersion of metal nanoparticles or metal oxide nanoparticles is selected to have good miscibility with the carrier solution. In a typical embodiment, the solvent for the dispersion of metal nanoparticles or metal oxide nanoparticles is the same as the solvent for the carrier solution, for example, water. In another embodiment, when the solvent for the carrier solution is a mixed solvent of multiple types of solvents, the solvent for the dispersion of metal nanoparticles or metal oxide nanoparticles may be a solvent having the same composition as the mixed solvent, or may be a solvent having substantially the same composition as or a similar composition to the mixed solvent and having good miscibility. The stirring speed, stirring time and other conditions during stirring and mixing may be appropriately set taking into consideration the volume of the solution and other factors.

[0066] Step S130: An adjuvant is added to the mixture obtained in step S120, and the mixture is further stirred and mixed. The method of adding the auxiliary agent to the mixed solution may be appropriately selected taking into consideration the form of the auxiliary agent (e.g., solid or liquid), the amount to be added, etc. Furthermore, the stirring speed, stirring time, and other conditions during stirring and mixing may be appropriately set taking into consideration the volume of the solution, the amount of the auxiliary agent added, etc., as in step S120.

[0067] [Antibacterial composition] Next, the antibacterial composition of the present invention will be described.

[0068] The antibacterial composition of the present invention contains the antibacterial complex of the present invention or the antibacterial complex solution of the present invention described above. That is, the antibacterial composition of the present invention contains the antibacterial complex of the present invention or the antibacterial complex solution of the present invention as an active ingredient. Furthermore, the antibacterial composition of the present invention may contain optional ingredients such as surfactants, thickeners, colorants, fillers, preservatives, antifreeze agents, stabilizers, and / or pH adjusters, as necessary.

[0069] The antibacterial composition of the present invention can be formulated into a desired dosage form depending on the purpose of use, the target substance, etc. Specific examples of the formulation include solid formulations such as dusts, wettable powders, water-dispersible granules, water-soluble powders, water-soluble granules, and granules; and liquid formulations such as emulsifiable concentrates, solutions, microemulsions, aqueous suspensions, aqueous emulsions, and suspoemulsions, and can be formulated into a wide variety of formulations. Furthermore, even if the formulation is in a dosage form other than the specific dosage forms exemplified above, it can be made into any formulation that can be applied by contacting the target substance directly or after dilution.

[0070] Here, as a representative embodiment of the antibacterial composition of the present invention, an agricultural antibacterial composition that is particularly suitable for agricultural use will be described.

[0071] As used herein, "particularly suitable for agricultural use" typically means that it is particularly suitable for use in preventing damage to agricultural crops by diseases and pests.

[0072] As used herein, "crops" typically refers to cultivated plants grown in fields. In addition, plants that grow naturally in the mountains and are used for food, i.e., wild vegetables, are also included in crops. Cultivated plants are not particularly limited in terms of their cultivation method (cultivation technique). Examples include open-field cultivation, greenhouse cultivation, hydroponic cultivation, forced cultivation, log cultivation, mushroom bed cultivation, and factory cultivation. Semi-cultivated plants may also be grown in a state intermediate between wild and cultivated conditions, where humans have intervened with wild plants.

[0073] One aspect of the antibacterial composition according to this embodiment is the antibacterial composite of the present invention described above, wherein the metal or metal oxide is copper nanoparticles, and the adjuvant is a magnesium salt, a calcium salt, or a combination thereof, or a quaternary ammonium salt. In other words, the antibacterial composition according to this embodiment is a copper-containing composition having antibacterial properties that is particularly suitable for agricultural applications. The antibacterial composition according to this embodiment also preferably contains the antibacterial complex solution of the present invention, and more preferably the solvent of the solution is water. When the antibacterial composition according to this embodiment is formulated into a liquid preparation (e.g., an aqueous suspension preparation), the preparation (copper agent) may be usable as is, or may be usable after being appropriately diluted with any solvent (e.g., water).

[0074] The antibacterial composition according to this embodiment is typically suitable for use on fruits and vegetables. However, the agricultural crops to which the antibacterial composition according to this embodiment can be applied are not limited to fruits and vegetables. For example, other agricultural crops include cereals (rice; barley, wheat, rye, and other grains; corn; buckwheat, etc.).

[0075] In this specification, "fruits and vegetables" typically refers to crops obtained from cultivated fruit trees, edible trees, woody plants, herbaceous plants, etc., but wild vegetables are also included in the term "fruits and vegetables."

[0076] Specifically, fruits and vegetables include fruits, vegetables, mushrooms, and wild plants. Fruits refer to fruits that are eaten. Vegetables are classified according to the part used, and include leafy vegetables, root vegetables, and fruiting vegetables. Mushrooms refer to organisms classified as fungi that form fruiting bodies large enough to be seen with the naked eye, or the fruiting bodies themselves that are eaten. Wild plants refer to plants that grow wild in the mountains and are eaten.

[0077] Examples of fruits, vegetables, and wild plants include strawberries, which can be classified as both fruits and vegetables (fruit vegetables). Also, chives, for example, can be classified as both vegetables (leafy vegetables) and wild plants. It should be noted that, in this way, it may not be possible to fit a single crop into a single classification when it comes to crops included in fruits and vegetables. On the other hand, although one of the features of the antibacterial composition according to this embodiment is its versatility, it is practically impossible to comprehensively demonstrate its effectiveness for all crops included in fruits and vegetables.

[0078] Therefore, below, as an example of classification (grouping) of fruits and vegetables to which the antibacterial composition of this embodiment can be applied, we will explain an embodiment in which we refer to the classification of applicable crops in the pesticide registration under the jurisdiction of the Ministry of Agriculture, Forestry and Fisheries. Referrer URL: https: / / www.maff.go.jp / j / nouyaku / n_sasshin / group / top.html https: / / www.maff.go.jp / j / nouyaku / n_sasshin / group / sakumotu_bunrui.html

[0079] In this embodiment, fruits and vegetables include fruits, vegetables, and edible fungi.

[0080] Fruit trees include citrus fruits, pome fruits, stone fruits, berries and other small fruits.

[0081] Vegetables include tuberous and corm vegetables, root vegetables, bulb vegetables, pulses (seeds), legume vegetables (immature), fruiting vegetables (cucurbits), fruiting vegetables (solanaceous plants), brassica vegetables (flowerhead and stem Brassicas), leafy vegetables, stalk and stem vegetables, and edible flowers.

[0082] Mushrooms include Enokitake, King Oyster Mushroom (Kaori Oyster Mushroom), Shiitake, Nameko, Hiratake, Bunashimeji, Maitake, and Tsukuritake.

[0083] More specifically, stone fruits included in fruit trees include peaches, small stone fruits, and cherries. Peaches include peaches and nectarines. Small stone fruits include apricots, plums, and prune, as well as hybrids between these crops.

[0084] Here, bacterial peach hole is known as a disease that occurs in peach cultivation. In Japan, the pathogenic bacteria of peach bacterial canker infects branches in the previous autumn, overwintering, and then forming spring canker lesions (a source of infection) in the following spring, which then disperse to the surrounding area. When spring canker lesions occur frequently, the risk of severe damage from peach bacterial canker increases, making canker removal and pesticide spraying important control measures. Furthermore, because spring canker lesions develop over a long period of time, multiple canker removal and pesticide spraying are necessary. Specific control methods include spraying Bordeaux mixture at the beginning of flowering to prevent infection from spring canker lesions; then, preventive spraying, primarily with antibiotics, every 10–14 days from flowering to harvest; and multiple canker removal procedures between the beginning of flowering and just before harvest. Furthermore, spraying Bordeaux mixture two to three times after harvest, from mid-to-late September to early October, prevents autumn infection of branches. Other measures being taken include installing windbreak nets and hedges around fields and applying fruit bags early to reduce damage to fruit.

[0085] Thus, in order to reduce damage caused by peach bacterial bore, it is important to keep the density of the fungus in the field low at all times. However, from the perspective of reducing the burden on agricultural workers, an effective control method using pesticide spraying is required. On the other hand, as mentioned above, while conventional Bordeaux mixture has excellent antibacterial and disinfectant properties, it has the problem of copper toxicity (phytotoxicity) due to the copper sulfate it contains. Furthermore, there are organic copper pesticides that are less likely to cause phytotoxicity problems, but they cannot be used in organic farming and are undesirable from the perspective of aiming for agricultural production methods that minimize the burden on the environment.

[0086] In view of these circumstances, by using the antibacterial composition according to this embodiment as an agent to replace conventional inorganic copper agents such as Bordeaux mixture, it is expected that an antibacterial effect equivalent to or superior to that of conventional agents can be obtained with a lower copper content or a lower application rate, with less impact on the environment. In the examples described below, test examples will be described in which the antibacterial performance of the antibacterial complex solution and antibacterial composition containing the antibacterial complex of the present invention was evaluated by tests using actual peach borer pathogenic bacteria and potted peach trees.

[0087] Peach bacterial hole is known to occur not only in peaches but also in the cultivation of apricots, nectarines, and plums. Therefore, an agent (antibacterial composition) that has a certain level of effectiveness against peach bacterial hole may be effective in the cultivation of the stone fruits mentioned above. Furthermore, from the perspective of plant defense mechanisms, it may be applicable to a wider range of fruit trees, such as citrus fruits and pome fruits, to other plant diseases that have similar symptoms and symptoms to peach bacterial hole, or diseases that are infected by similar pathogenic bacteria and develop in similar areas. It is also expected that the agent may be applicable to vegetables and mushrooms.

[0088] The present invention will be described in more detail below based on examples, but it should be noted that the present invention is not limited to these examples. [Example]

[0089] [Preparation of metal nanoparticles] Nanoparticle manufacturing methods can be broadly divided into top-down (pulverization) methods, in which large lumps are pulverized, and build-up (aggregation) methods, in which nanoparticles are grown from small molecular-level raw materials. The latter includes dry (gas phase) methods and wet (liquid phase) methods, with typical dry methods including thermal evaporation, laser beam methods, sputtering, and CVD (vapor phase reaction). Typical wet methods include thermal decomposition, chemical reduction, and plasma methods. Reference: Atsushi Hyono and Toru Yonezawa, Nanotechnology Lectures (VII), "Fundamentals and Recent Topics of Metal Nanoparticles," Journal of the Japan Society of Color Materials, Vol. 82, No. 10, pp. 468-474 (2009). Nanoparticles produced by either method can be used to produce the target composite. In this example, the metal nanoparticles were produced by a wet method.

[0090] [Preparation of Metal Nanoparticle Dispersion] An example of a method for preparing a metal nanoparticle dispersion is shown below. International Publication No. WO2003 / 032932 "A method for producing a hair correction fluid in which titanium group metal ultrafine particles are finely dispersed in water, the method comprising: using a high-voltage discharge generator having a titanium group metal electrode and a counter electrode in water to generate a plasma discharge between the metal and the counter electrode in water, thereby ultrafinely dispersing titanium group metal ultrafine particles in water." (Claim 2) A copper nanoparticle dispersion was prepared using a copper electrode as the electrode in the above manufacturing method. In addition, a silver nanoparticle dispersion was prepared by the same manufacturing method as above, except that a silver electrode was used as the electrode. The particle sizes of the obtained copper nanoparticles and silver nanoparticles were measured by dynamic light scattering (DLS) using a laser light source. The concentrations of the obtained copper nanoparticles and silver nanoparticles were measured using an inductively coupled plasma emission spectrometer (ICP).

[0091] [Preparation of copper nanoparticle dispersion] Another example of a method for producing copper nanoparticles is shown below. Patent Publication No.: JP 2017-071816 A "Preparing a first aqueous solution containing copper ions and citric acid and adjusted to a pH range of 10 or more and less than 12; preparing a second aqueous solution containing ascorbic acid and adjusted to a pH range of 10 or more and less than 12; A step of mixing the first aqueous solution and the second aqueous solution to reduce the copper ions and obtain a dispersion of copper nanoparticles; "(Claim 1) A method for producing copper nanoparticles, comprising: A copper nanoparticle dispersion was prepared with reference to the above. [Preparation of silver nanoparticle dispersion] Another example of a method for producing silver nanoparticles is shown below. Patent Publication No.: JP 2008-88480 A 1.0 g of silver oxide (average particle size 1.5 μm) and 1.0 g of soluble starch were added to 98 g of distilled water. The mixture was then heated at 60°C for 1 hour while stirring. The solution was initially black with suspended silver oxide, but as the reduction reaction progressed, it turned yellow and finally yellowish brown, confirming the production of silver. A portion of the solution was diluted with distilled water and observed under an electron microscope, revealing that silver nanoparticles with a particle size of 10-30 nm had been obtained." (Paragraph 0025, Example 1, Figure 1) A silver nanoparticle dispersion was prepared with reference to the above. The particle sizes of the obtained copper nanoparticles and silver nanoparticles were measured by dynamic light scattering (DLS) using a laser light source. The concentrations of the obtained copper nanoparticles and silver nanoparticles were measured using an inductively coupled plasma emission spectrometer (ICP).

[0092] [Preparation of antibacterial complex] [Preparation of antibacterial copper nanoparticle-loaded cellulose nanofibers] 83.5 g of cellulose nanofiber (manufactured by Sugino Machine Co., Ltd.) with a concentration of 2 wt% was added to 500 mL of pure water and stirred for 30 minutes. 835 mL of the copper nanoparticle dispersion (copper content: 87.6 mg, 104.9 ppm) was then added and further stirred to obtain a brown suspension. Next, 3.3 g of magnesium chloride was added as an auxiliary agent, and the mixture was stirred and mixed for 30 minutes, causing the copper nanoparticles to be adsorbed onto the cellulose nanofibers through electrostatic interaction, thereby obtaining a composite containing magnesium chloride and copper nanoparticle-supported cellulose nanofibers in which copper nanoparticles were supported on the cellulose nanofibers. The obtained complex was mixed with water (i.e., a solution containing the antibacterial complex and the solvent water), and the supernatant of the solution in the reaction vessel after stirring was clear. This confirmed that in the antibacterial complex solution obtained by the above method, the copper nanoparticles that were originally dispersed in the solvent water were supported on the cellulose nanofibers, which made the supernatant of the solution clear.

[0093] [Preparation of antibacterial complex solution] An antibacterial complex solution having the component composition shown in Table 1 below was prepared according to the same procedure as above. Table 2 shows the three mass ratios mentioned above for the content of each component of the complex (carrier, metal nanoparticles, and auxiliary agent) contained in each antibacterial complex solution.

[0094] (Examples 1 to 7) The carriers used were chitosan nanofibers, chitin nanofibers, and cellulose nanofibers (all manufactured by Sugino Machine Corp.) Two types of cellulose nanofibers were used: those produced by the TEMPO method and those produced by the mechanical crushing method. The above copper nanoparticle dispersion was used as the metal nanoparticles. Magnesium chloride was used as an adjuvant. Although the component compositions of the antibacterial complex solutions in Examples 5A and 5B are the same, the difference lies in the carrier used: Example 5A used cellulose nanofibers produced by the TEMPO method, while Example 5B used cellulose nanofibers produced by the mechanical crushing method. In all of the solutions of Examples 1 to 7, the supernatant of the solution after preparation was clear, and it was confirmed that the copper nanoparticles were supported on the predetermined carrier.

[0095] (Examples 8 to 15) The carriers used were cellulose nanofibers produced by the TEMPO method and cellulose nanofibers produced by the mechanical crushing method (both manufactured by Sugino Machine Co., Ltd.). The above copper nanoparticle dispersion was used as the metal nanoparticles. As an adjuvant, an aqueous solution of benzalkonium chloride (concentration: 10 w / v%) was used. In all of the solutions of Examples 8 to 15, the supernatant of the solution after preparation was clear, and it was confirmed that the copper nanoparticles were supported on the predetermined carrier.

[0096] (Examples 16 to 18) Chitosan nanofibers, chitin nanofibers, and cellulose nanofibers produced by the TEMPO method (all manufactured by Sugino Machine Co., Ltd.) were used as carriers. The silver nanoparticle dispersion liquid was used as the metal nanoparticles. As an adjuvant, an aqueous solution of benzalkonium chloride (concentration: 10 w / v%) was used. In all of the solutions of Examples 16 to 18, the supernatant of the solution after preparation was clear, confirming that the silver nanoparticles were supported on the predetermined carrier.

[0097] (Examples 19 to 25) For comparison, solutions of Examples 19 to 25 were prepared under the conditions shown in Table 1. The stirrer and stirring conditions used were the same as those of Examples 1 to 18. Chitosan nanofibers, chitin nanofibers, and cellulose nanofibers prepared by mechanical pulverization (all manufactured by Sugino Machine Co., Ltd.) were used as carriers. The above copper nanoparticle dispersion was used as the metal nanoparticles. As an adjuvant, an aqueous solution of benzalkonium chloride (concentration: 10 w / v%) was used. In Examples 19 to 21, a mixed solution of carrier and copper nanoparticles containing no adjuvant was obtained. The supernatant of the prepared solution was brownish-red. From this, it is believed that in the solutions of Examples 19 to 21, the copper nanoparticles were not supported on the carrier and remained in the supernatant. The solution of Example 22 is a mixed solution of a carrier and an auxiliary agent that does not contain metal nanoparticles. The solution of Example 23 is an aqueous solution of benzalkonium chloride (concentration: 10 w / v %), which was used as an adjuvant in Examples 8 to 18. The solutions of Examples 24 and 25 are copper nanoparticle dispersions adjusted to have copper nanoparticle contents of 260 ppm and 210 ppm, respectively.

[0098] [Table 1]

[0099] [Table 2]

[0100] The notes in the remarks column of Table 1 also apply to Tables 3, 6, 7, and Figure 3 below.

[0101] The solutions of Examples 1 to 25 thus prepared were subjected to an antibacterial test by the method described below. For convenience, the solutions of Examples 1 to 15, 19 to 21, 24, and 25 will also be referred to as "copper-containing solutions," and the solutions of Examples 16 to 18 will also be referred to as "silver-containing solutions."

[0102] [Antibacterial test] <Test Example 1> The test bacteria used was the peach borer (scientific name: Xanthomonas arboricola pv. pruni), a plant pathogen, and the minimum inhibitory concentration (MIC) was evaluated. The MIC values ​​were measured using a microbial metabolic activity measurement method based on the water-soluble tetrazolium salt reduction reaction (Reference: Journal of the Japan Food Chemical Industry Association, Vol. 62, No. 7, 321-327, 2015).

[0103] Preparation of a standard curve for determining the growth of the peach borer fungus The bacterial peach borer was suspended in nutrient bouillon (NB) liquid medium and incubated overnight at 27°C. 8 cfu / mL, and then serially diluted 10-fold to obtain 10 1 The concentration was adjusted to cfu / mL. NB liquid medium was used for all dilutions. Of these serially diluted solutions, 10 7 ~10 1 Add 95 μL of each cfu / mL solution to a 96-well plate, with each well containing approximately 10 6 ~10 0 The bacterial count was determined to be cfu. To each well, 95 μL of NB liquid medium and 10 μL of a mixture of 1-methoxy-PMS (1-Methoxy-5-methylphenazinium methylsulfate) and WST-1 [2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt] (final concentrations of 0.04 mM and 0.5 mM, respectively) were added, bringing the total volume in each well to 200 μL. As a control, 10 μL of a mixture of 1-methoxy-PMS and WST-1 was added to 190 μL of NB liquid medium. Each dilution and control was prepared in triplicate wells. The prepared plate was placed in a plate reader, and the temperature was set at 27°C, and the absorbance at 450 nm was measured every hour. The absorbance of each bacterial amount was expressed as the average value of three wells. From the measurement results, a calibration curve was created by plotting the incubation time (in hours) at which the absorbance of the wells with each bacterial amount exceeded 0.5 on the vertical axis and the natural logarithm of the bacterial amount on the horizontal axis. From this calibration curve, it was found that when the initial bacterial amount was 1 cfu, it took approximately 50 hours for the absorbance to exceed 0.5. In other words, if the absorbance is less than 0.5 after incubation for 50 hours or more, it can be determined that there is no bacterial growth.

[0104] Measurement of MIC values The solutions of Examples 1, 5A, 5B, 8, and 24, and the copper sulfate solution were subjected to the test. Each copper-containing solution was diluted to a copper concentration of 100 ppm, and these were used as stock solutions, which were then serially diluted 2-fold up to 16-fold to prepare six types of diluted solutions (copper-containing compositions), including the stock solutions. The copper sulfate solution was prepared by dissolving copper sulfate pentahydrate in water to a copper concentration of 1000 ppm, and then diluted to a copper concentration of 100 ppm. Subsequent serial dilutions were carried out in the same manner as for other copper-containing solutions. All dilutions were made using NB liquid medium. 95 μL of each copper-containing solution and six dilutions of the copper sulfate solution were added to a 96-well plate. About 10 minutes there 6 A suspension of 95 μL of peach borer bacteria prepared in NB liquid medium at a concentration of cfu / mL was added to each well, along with 10 μL of a mixture of 1-methoxy-PMS and WST-1 (final concentrations of 0.04 mM and 0.5 mM, respectively, as described above) for a total volume of 200 μL. As a control, NB liquid medium was added instead of the bacterial suspension. Each dilution and control was prepared in triplicate wells. The prepared plate was placed in a plate reader and cultured at a temperature of 27°C for approximately 70 hours, during which the absorbance at 450 nm was measured every hour. The representative value was calculated by subtracting the average absorbance of each control from the average absorbance of the copper-containing solution (copper-containing composition) to which the bacterial solution was added, and the minimum copper concentration at which this representative value did not exceed 0.5 during cultivation was used as the MIC value for each copper-containing solution. The same applies to copper sulfate solutions. The results are shown in Table 3.

[0105] [Table 3]

[0106] As shown in Table 3, it was confirmed that Examples 1, 5A, 5B, and 8 had antibacterial effects equal to or greater than those of the copper sulfate solution. In particular, in Examples 1 and 8, MIC values ​​(5.9 ppm and less than 1.5 ppm) were obtained that were significantly lower than the MIC value (23.8 ppm) obtained with the copper sulfate solution, and were also lower than the MIC value (11.9 ppm) obtained with the solution (copper nanoparticle dispersion) of Example 24. This demonstrates that the antibacterial composition of the present invention provides an antibacterial effect that exceeds that of copper nanoparticles alone. In addition, when the relationship between copper concentration and bacterial quantity was plotted on a log-log graph with the common logarithm of bacterial quantity (cfu) on the vertical axis and the common logarithm of the copper concentration (ppm) in the test solutions (six types of diluted solutions) on the horizontal axis, it was found that in Example 1, the bacterial quantity tended to decrease at a lower copper concentration than in the solution (copper nanoparticle dispersion) of Example 24. Furthermore, in Example 8, which used a benzalkonium chloride aqueous solution as an adjuvant, the bacterial quantity decreased at a particularly lower copper concentration than in the example using magnesium chloride, suggesting that at least the antibacterial activity of not only the copper nanoparticles but also the benzalkonium chloride was effectively acting. Furthermore, since the test results for Examples 5A and 5B were the same, no difference in MIC values ​​was observed due to differences in the manufacturing method of the cellulose nanofibers used as the carrier in this test example. Furthermore, when plotted on the double logarithmic graph described above, Examples 5A and 5B showed similar trends in antibacterial activity.

[0107] <Test Example 2> A test to confirm phytotoxicity was conducted using potted peach trees. The test solutions used were the solution of Example 2, a 10-fold dilution of the solution of Example 2, a 2000-fold dilution of a commercially available inorganic copper pesticide (Kocide (registered trademark) 3000, copper concentration 3000 ppm) (the manufacturer's recommended spray concentration for peach bacterial borer from post-harvest to defoliation), and water. Here, the copper concentration in the solution of Example 2 and the diluted solution of the solution of Example 2 was adjusted to be approximately the same as the copper concentration (150 ppm) in the diluted solution of a commercially available inorganic copper pesticide. 500 mL of each test solution was sprayed three times on three pots, and then all the leaves were inspected, and the percentage of the number of leaves that showed phytotoxicity to the total number of leaves inspected was taken as the phytotoxicity incidence rate (%). For each test solution, the mean ± standard deviation of three pots is shown in Table 4.

[0108] [Table 4]

[0109] As shown in Table 4, the solution of Example 2, whether diluted or not, had a lower incidence of phytotoxicity than commercially available inorganic copper pesticides. This demonstrates that the antibacterial composition of the present invention is particularly suitable for agricultural use, as it can achieve antibacterial effects equivalent to or superior to those of conventional copper agents at lower application rates.

[0110] <Test Example 3> A test to confirm the effectiveness of the control was conducted using potted peach trees. The test solutions used were the solution of Example 3, the solution of Example 6, a 1000-fold diluted solution of a commercially available inorganic copper pesticide (the agent used in Test Example 2) (the manufacturer's recommended spray concentration for peach bacterial borer before flowering), and water. 500 mL of each test solution was sprayed onto three pots. The next day, the seedlings were shaken to remove some of the leaves, and then the fungal solution (1 × 10 8 cfu / mL) was sprayed. This process was repeated three times at two-week intervals, and the pots were then left in the field for approximately six months until flowering in the following spring. After all the new shoots had appeared, spring-type branch lesions were confirmed, and the percentage of diseased buds among the total number of buds surveyed was calculated. For each test solution, the mean ± standard deviation of three pots is shown in Table 5.

[0111] [Table 5]

[0112] As shown in Table 5, the solutions of Examples 3 and 6 both had lower copper concentrations than commercially available inorganic copper pesticides, yet the disease incidence was equal to or lower than those. This demonstrates that the antibacterial composition of the present invention is an antibacterial composition particularly suitable for agricultural use, as it can achieve antibacterial effects equal to or better than conventional copper formulations with a lower copper content than conventional copper formulations.

[0113] <Test Example 4> The antibacterial activity against general bacteria was evaluated using a microbial metabolic activity measurement method based on the water-soluble tetrazolium salt reduction reaction (Reference: Journal of the Japan Food Chemical Industry Association, Vol. 62, No. 7, 321-327, 2015).

[0114] The solutions tested are shown in Table 6. Here, for the solutions of Examples 1, 4, 5A, 5B, 7, 8 to 11, 15, 17, and 18, the solutions with the copper concentrations shown in Table 6 were used as stock solutions, and these were diluted with Normal Bouillon (NB) liquid medium in a 2-fold serial dilution up to 128 times, and eight types of diluted solutions (copper-containing compositions) including the stock solutions were used. For comparison, the solution of Example 24 (copper nanoparticle dispersion) and a copper sulfate solution (concentration 260 ppm) having the same copper concentration as the solution of Example 24 were also serially diluted with NB liquid medium and used.

[0115] 100 μL of each test solution (undiluted solution and diluted solution) was added to an incubation vessel (a well of a 96-well microplate). Approximately 1 x 10 Escherichia coli (ATCC8739 strain) or Staphylococcus aureus (ATCC6538 strain) suspended in NB liquid medium was added to the plate. 5 cfu / 80 μL was added. Furthermore, 20 μL of a mixture of 5 mM WST-1 and 0.2 mM 1-methoxy-PMS was added as a detection reagent, and the samples were incubated at 35°C. The absorbance at 450 nm was measured at regular intervals (20 minutes for E. coli and 30 minutes for Staphylococcus aureus) for approximately 16 to 24 hours. From the results obtained, the time until the absorbance exceeded 0.5 was calculated, and the initial number of bacteria (cfu) was estimated from a calibration curve that had been measured in advance by changing the number of inoculated bacteria, and the minimum inhibitory concentration (MIC) of the test solution at which the initial number of bacteria was 0 was calculated. The results are shown in Table 6.

[0116] [Table 6]

[0117] As shown in Table 6, for E. coli, the solution of Example 24 (copper nanoparticle dispersion) had the same MIC value as the copper sulfate solution, but the solutions of Examples 1, 4, 5A, 5B, 7, 8 to 11, 15, 17, and 18 all had significantly lower MIC values ​​than the solution of Example 24 and the copper sulfate solution. In particular, the solutions of Examples 8 to 11 and 15, which contained benzalkonium chloride as an adjuvant, had significantly lower MIC values ​​than the solution of Example 24 and the copper sulfate solution, demonstrating high antibacterial activity. The higher the mass ratio [(adjuvant) / (metal)], the lower the MIC value tended to be. A similar trend was observed for the solutions of Examples 17 and 18, in which the metal was silver. In addition, when the relationship between copper concentration and initial bacterial count was plotted on a log-log graph with the common logarithm of the initial bacterial count (cfu) on the vertical axis and the common logarithm of the copper concentration (ppm) in the test solutions (eight dilutions) on the horizontal axis, it was observed that the copper concentration at which the initial bacterial count decreased when magnesium chloride was used as an adjuvant tended to be similar to that of the solution of Example 24 and the copper sulfate solution. This suggests that the antibacterial composition of the present invention can achieve antibacterial effects equivalent to or superior to conventional copper agents with a lower copper content than conventional copper agents. Furthermore, when benzalkonium chloride was used as an adjuvant, the initial bacterial count tended to decrease, especially at low copper concentrations, suggesting that not only the antibacterial activity of copper nanoparticles but also the antibacterial activity of benzalkonium chloride were effective.

[0118] On the other hand, for Staphylococcus aureus, the solution of Example 24 had a MIC value two times higher than that of the copper sulfate solution. However, a double logarithmic graph obtained in the same manner as described above for E. coli confirmed that the tendency for the initial cell count to decrease with copper concentration was similar. In other words, the difference in MIC values ​​between the solution of Example 24 and the copper sulfate solution can be explained by the fact that the concentration (dilution level) at which the initial cell count was found to be 0 differed by one level between the solution of Example 24 and the copper sulfate solution. Similarly, when the solutions of Examples 1, 4, and 5A were compared with the copper sulfate solution, the solutions of Example 4 and Example 5A had higher MIC values ​​than the copper sulfate solution. However, the plots on the double logarithmic graphs described above indicated that the copper concentrations at which the initial cell count decreased for the solutions of Example 4 and Example 5A tended to be similar to those of the copper sulfate solution. In other words, when the results for the peach borer bacteria shown in Test Example 1 and the test results for Escherichia coli mentioned above are taken into consideration, it can be said that, although there are slight differences depending on the type of bacteria, the test results for Staphylococcus aureus also suggest that the antibacterial composition of the present invention can achieve antibacterial effects equivalent to or superior to those of conventional copper agents with a copper content lower than that of conventional copper agents. Furthermore, the solutions of Examples 8 to 11 containing benzalkonium chloride as an adjuvant had MIC values ​​significantly lower than those of the solution of Example 24 and the copper sulfate solution, demonstrating high antibacterial activity, and a tendency was observed for the MIC value to decrease as the mass ratio [(adjuvant) / (metal)] increased. Furthermore, in the plots on the log-log graph described above, similar to the test results for E. coli, when benzalkonium chloride was used as an adjuvant, the initial bacterial count tended to decrease, particularly at low copper concentrations, suggesting that the antibacterial activity of not only the copper nanoparticles but also the benzalkonium chloride was effective.

[0119] Here, the values ​​of the mass ratio [(adjuvant) / (metal)] and the MIC values ​​for Escherichia coli or Staphylococcus aureus are plotted on a double logarithmic graph, and the results are shown in FIG. 2, the plots indicated by open diamonds are the MIC values ​​against E. coli of the solutions of Examples 1, 5A, 5B, and 7, and the plots indicated by closed diamonds are the MIC values ​​against E. coli of the solutions of Examples 8 to 11, and 15. The plots indicated by open squares are the MIC values ​​against Staphylococcus aureus of the solutions of Examples 1 and 5A, and the plots indicated by closed squares are the MIC values ​​against Staphylococcus aureus of the solutions of Examples 8 to 11. The plots indicated by closed circles and open circles are the MIC values ​​against E. coli and Staphylococcus aureus, respectively, of the solution of Example 24.

[0120] As shown in Figure 2, the tendency for the MIC value to decrease as the mass ratio [(adjuvant) / (metal)] increases is more pronounced when benzalkonium chloride is used as an adjuvant than when magnesium chloride is used.

[0121] Therefore, for the solutions of Examples 9 to 11 and 15, which contained benzalkonium chloride as an adjuvant and in which the cellulose nanofibers used as carriers were manufactured by the same method, the MIC values ​​converted to benzalkonium chloride (BzCl ppm) were calculated instead of the MIC values ​​converted to copper (Cu ppm) shown in Table 6, and the MIC values ​​(BzCl ppm) and the mass ratio [(adjuvant) / (metal)] (i.e., the mass ratio [(BzCl) / (Cu)]) were plotted on a double logarithmic graph, resulting in the results shown in Figure 3. 3, the plots indicated by black diamonds represent the MIC values ​​of the solutions of Examples 9 to 11 and 15 against Escherichia coli, and the plots indicated by black squares represent the MIC values ​​of the solutions of Examples 9 to 11 against Staphylococcus aureus. The plots indicated by black circles and white circles represent the MIC values ​​of the solution of Example 24 against Escherichia coli and Staphylococcus aureus, respectively.

[0122] As shown in FIG. 3, in relation to the MIC value converted to benzalkonium chloride, the MIC value tended to increase as the mass ratio [(adjuvant) / (metal)] increased. This suggests that in an embodiment containing benzalkonium chloride as an adjuvant, the presence of a metal (copper), which is an antibacterial material, can produce a synergistic effect with the antibacterial properties of benzalkonium chloride. Furthermore, this effect is thought to be more pronounced when the benzalkonium chloride content in the composition is low and the metal content is similarly low (i.e., when the mass ratio [(adjuvant) / (metal)] is small).

[0123] On the other hand, when the results of this test example are focused on the type of adjuvant, the following can be seen. Looking at the solutions of Examples 1, 4, 5A, 5B, and 7, which all contain magnesium chloride as an adjuvant, the MIC values ​​for E. coli in the solutions of Examples 1, 4, 5A, and 5B are lower than the MIC value (87.5 ppm) in the solution of Example 7. For example, the ratio of the MIC value (64.5 ppm) in the solutions of Examples 5A and 5B to the MIC value in the solution of Example 7 is approximately 0.74. Similarly, looking at the solutions of Examples 8 to 11 and 15, which have in common the fact that they contain benzalkonium chloride as an adjuvant, the MIC values ​​for Escherichia coli in the solutions of Examples 8 to 11 are lower than the MIC value (22.9 ppm) in the solution of Example 15. For example, the ratio of the MIC value (13.9 ppm) in the solution of Example 11 to the MIC value in the solution of Example 15 is approximately 0.61.

[0124] In other words, it can be said that the solutions of Examples 7 and 15 both exhibit superior antibacterial activity compared to the solution of Example 24 (copper nanoparticle dispersion) and the copper sulfate solution, but if these are positioned as the above-mentioned "reference samples," then the solutions of Examples 1, 4, 5A, 5B, and 8 to 11 can be evaluated as exhibiting even superior antibacterial activity.

[0125] Thus, in evaluating the antibacterial properties of the antibacterial composite of the present invention, it is possible to evaluate from multiple perspectives by combining various types and content ratios (mass ratios of the contents) of the components contained in the composite. As a result, it is possible to provide an antibacterial composition that can achieve the desired antibacterial effect depending on the purpose of use, target object, etc., and that can be applied to agriculture, industrial applications other than agriculture, such as medical care, nursing care, livestock and fisheries, and food, as well as general applications.

[0126] <Test Example 5> The adhesion to the substrate and residual effectiveness were evaluated by the following methods.

[0127] As the substrate, a membrane filter (manufactured by Advantec Toyo Co., Ltd., cellulose mixed ester type, pore size 0.20 μm) was used.

[0128] The solutions tested are shown in Table 7. Here, for the solutions of Examples 1, 4, 5A, 7, 8 to 11, and 15, diluted solutions (copper-containing compositions) diluted so that the copper concentrations were the values ​​shown in Table 7 were used. For comparison, the solutions of Examples 22, 23, and 25 (copper nanoparticle dispersions), and a copper sulfate solution having the same copper concentration as the solution of Example 25 (concentration: 210 ppm) were used.

[0129] 1 mL of each of the solutions of Examples 5A, 8, 9, 11, 15, 22, 23, and 25 and the copper sulfate solution was diluted with 9 mL of ultrapure water, filtered through a membrane filter, and dried in vacuum for 4 hours. For the solutions of Examples 1 and 4, the carrier concentration in the solution was higher than that of the other copper-containing solutions, so 0.4 mL of each was diluted with 9.6 mL of ultrapure water, 0.2 mL of the solution of Example 7 was diluted with 9.8 mL of ultrapure water, and 0.5 mL of the solution of Example 10 was diluted with 9.5 mL of ultrapure water, and each was filtered through a membrane filter and dried in vacuum for 4 hours. In this way, by adjusting the dilution ratio taking into consideration the carrier concentration in each solution, the substances remaining on the membrane filter after filtration and drying were prevented from peeling off from the membrane filter.

[0130] Each membrane filter was cut into 5 x 20 mm pieces, immersed in ultrapure water with stirring for 10 minutes, and dried in a vacuum for 4 hours. After repeating the process of immersion in ultrapure water with stirring and vacuum drying twice, the membrane filters were placed upright in a 96-well microplate and sterilized with ethylene oxide gas. Then, add the bacterial solution (1 × 10 5 cfu / 180 μL NB medium) and WST-1 reagent (20 μL of a mixture of 5 mM WST-1 and 200 μM 1-methoxy-PMS) were added, and the absorbance at 450 nm was measured at regular intervals (20 minutes, 30 minutes, or 1 hour) while culturing at 35°C for approximately 16, 24, or 70 hours. The test bacteria used were Escherichia coli (ATCC8739 strain), Staphylococcus aureus (ATCC6538 strain), or bacterial peach borer.

[0131] In addition, to determine whether or not there was any effect due to the number of times the process of stirring and immersing in ultrapure water and vacuum drying was repeated, similar tests were conducted on samples in which each membrane filter was simply cut into pieces measuring 5 x 20 mm, as well as on samples in which the cut membrane filters had been subjected to the process of stirring and immersing in ultrapure water and vacuum drying once and on samples in which the cut membrane filters had been subjected to this process twice. In addition, as a control, a similar test was carried out using only a membrane filter without filtering any of the solutions.

[0132] From the results obtained, the time until the absorbance exceeded 0.5 was calculated, and the initial number of bacteria was estimated from a calibration curve that had been measured in advance with different numbers of inoculated bacteria, and the percentage of the inoculated number of bacteria (viable bacteria rate) was calculated. The test was performed with n=3. The results are shown in Table 7.

[0133] [Table 7]

[0134] In Table 7, the item names "0 immersion times," "1 immersion time," and "2 immersion times" refer to the number of times each cut membrane filter was subjected to the above-mentioned process of immersion in ultrapure water with stirring and vacuum drying.

[0135] As shown in Table 7, when the solutions of Example 1, Example 4, Example 5A, Example 7, Examples 8 to 11, and Example 15 were used for Escherichia coli, the viable cell rate for "zero immersion" was lower than the result for the control membrane filter alone (64.9%), indicating that the antibacterial properties of the complex are exerted by the complex being attached (retained) on the membrane filter. On the other hand, when the solution of Example 22 was used, no antibacterial activity was observed in the "zero immersion" case. When the solution of Example 23 was used, the viable cell rate in the "zero immersion" case was lower than that of the control membrane filter alone, presumably due to the antibacterial effect of benzalkonium chloride. When the solution of Example 25 was used, filtering a solution with a high copper concentration left many copper nanoparticles on the membrane filter, which is thought to have resulted in the antibacterial properties of the copper nanoparticles themselves, resulting in a particularly low viable bacteria rate for "zero immersion." However, it should also be noted that a similarly low viable bacteria rate (<0.001%) was obtained when the solution of Example 8 (copper concentration 126.9 ppm), which has a lower copper concentration, was used. In contrast, when a copper sulfate solution with the same copper concentration was used, the viable bacteria rate for "zero immersion" exceeded 100%. These results suggest that in order to achieve antibacterial activity when attached (retained) on the membrane filter used in this test example or on a substrate with similar materials and properties, not only must the antibacterial metal (copper) be present, but it must also be in the form of nanoparticles.

[0136] Next, looking at the viability of E. coli for "zero immersion," "one immersion," and "two immersion" tests, it can be seen that the viability was high when the solutions of Examples 4, 7, and 15 were used. A common feature of these solutions is that the mass ratio [(metal) / (carrier)] was 0.037 (Example 4), 0.035 (Example 7), and 0.030 (Example 15), which was lower than that of the other solutions. Note that the mass ratio [(metal) / (carrier)] of the solution of Example 1 was 0.048, indicating excellent antibacterial activity, and therefore the influence of differences in the type of carrier may also be considered a factor. However, due to the material of the membrane filter used in this test example, there is a limit to the amount of carrier (nanofiber) that can be retained by the membrane filter (approximately 60 μg / cm). 2 Considering also the degree to which antibacterial activity is maintained after adhesion (retention) to a substrate, a high mass ratio [(metal) / (carrier)] is desirable in order to have good adhesion to a predetermined substrate and to exert residual effectiveness by maintaining antibacterial activity even after adhesion (retention) to the substrate. Specifically, a mass ratio [(metal) / (carrier)] of 0.04 or more can be said to be a good guideline.

[0137] The results and discussion regarding E. coli above also apply to Staphylococcus aureus and bacterial peach borer. That is, when the solutions of Examples 5 and 8 were used, the viability rates of both Staphylococcus aureus and bacterial borer of peach were low for "zero immersion," "one immersion," and "two immersion," demonstrating excellent antibacterial activity. It is noteworthy that the solutions of Examples 5 and 8 had mass ratios of [(metal) / (carrier)] of 0.177 and 0.176, respectively, and that the mass ratios of [(adjuvant) / (carrier)] and [(adjuvant) / (metal)] were also close to each other. As mentioned above, the antibacterial activity of the complex may differ depending on whether the adjuvant is magnesium chloride or benzalkonium chloride, depending on whether the adjuvant itself has antibacterial properties. In other words, by keeping the content ratios (mass ratios) of each component contained in the complex at approximately the same level and varying the type (combination) of the components, it can be said that compositions having antibacterial properties suitable for various purposes and applications, as well as excellent adhesion to and residual activity on the target object (substrate) can be prepared. [Industrial Applicability]

[0138] The antibacterial complex of the present invention can be used in a variety of applications including agriculture as an antibacterial composition either as a solution containing the complex or by diluting it with an optional diluent. In particular, when copper nanoparticles are used as the metal nanoparticles, the composition can be used as an agricultural antibacterial composition that has a lower copper content or application rate than conventional copper agents, has a smaller impact on the environment, and provides antibacterial effects that are equal to or better than conventional antibacterial effects. Furthermore, in the present invention, nanoparticles of metals that have a certain antibacterial effect, such as copper or silver, can be used as the metal type, and therefore, in addition to agricultural applications, the present invention can also be applied to industrial applications such as medical care, nursing care, livestock and fisheries, and food, as well as general applications. Furthermore, since the antibacterial composite of the present invention has good adhesion to substrates, in the case of agricultural applications, in addition to the bark of target crops, it can exhibit antibacterial properties when attached to materials such as nonwoven fabrics, and is expected to also exhibit a certain degree of residual effectiveness.

Claims

1. An antibacterial complex comprising a carrier, a metal or metal oxide nanoparticles supported on the carrier, an adjuvant, and an optional solvent, the carrier is a nanofiber of a biopolymer selected from the group consisting of cellulose, chitosan, chitin, and combinations thereof; the metal or metal oxide is copper nanoparticles; the adjuvant is a magnesium salt, a calcium salt, or a combination thereof; the magnesium salt is selected from the group consisting of magnesium chloride, magnesium hydroxide, magnesium carbonate, magnesium sulfate, magnesium oxide, magnesium L-glutamate, magnesium stearate, trimagnesium phosphate, and combinations thereof; the calcium salt is selected from the group consisting of calcium chloride, calcium oxide, calcium citrate, calcium hydroxide, calcium carbonate, calcium lactate, calcium sulfate, and combinations thereof; a mass ratio of the content of the auxiliary agent to the content of the carrier [(auxiliary agent) / (carrier)] is 0.5 or more and 5 or less; a mass ratio of the content of the auxiliary agent to the content of the metal or metal oxide [(auxiliary agent) / (metal / metal oxide)] is 5 or more and 50 or less; An antibacterial complex solution, wherein the mass ratio of the content of the metal or metal oxide to the content of the carrier [(metal / metal oxide) / (carrier)] is 0.03 or more and 0.25 or less.

2. The antibacterial complex solution described in claim 1, wherein the particle size of the copper nanoparticles is 1 nm or more and 250 nm or less.

3. An antibacterial composition containing the antibacterial complex solution described in claim 1 or 2.

4. An agricultural antibacterial composition containing the antibacterial complex solution described in claim 1 or 2.

5. A method for producing the antibacterial complex solution according to claim 1 or 2, comprising: preparing a carrier solution containing the carrier; Adding a dispersion of copper nanoparticles to the carrier solution and stirring to mix; The adjuvant is added to the resulting mixture, and the mixture is further stirred and mixed. The method includes:

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