Anti-biofilm agent, composition, medical use appliance, and bacteria deposition prevention method using Anti-biofilm agent

Abstract

To provide an agent having an anti-biofilm function (function of inhibition of biofilm formation on a solid surface) that can continue and a processing method for function continuity.SOLUTION: The present invention employs a composition of an inorganic particle having an average primary particle size of 0.01-0.1 μm and represented by a general formula of (ZnO)x(Al2O3)1-x (in the formula, x is 0.5≤x<0.995). The composition of the inorganic particle is characterized by that, in a volume standard particle size distribution of the inorganic particle (secondary particle) of the composition in a water dispersion, a particle size D50 (median size) where frequency accumulation becomes 50% is 0.02-0.05 μm.SELECTED DRAWING: None

Description

[Technical field]

[0001] Much of the research on this subject has focused on the development of antibacterial surface materials and coatings (including paints), but antibacterial agents have poor ability to prevent biofilm growth, and they also wear out. The present invention relates to a bacterial adhesion inhibitor that prevents adhesion of bacteria to a solid surface and inhibits biofilm formation, and a method for inhibiting biofilm formation. [Background technology]

[0002] Biofilms are almost always present where solid surfaces come into contact with water. A biofilm is a community of microorganisms that have adsorbed to a solid surface and produced extracellular polysaccharides and have entered the matrix. In the following, the term "bacteria" will be used to represent microorganisms. Problems caused by biofilms include biofilm contamination of food packaging, food preparation utensils, cooking environments, medical equipment, medical equipment such as medical catheters, and medical environments, as well as increased frictional resistance of fluids in water pipes and ship bottoms, reduced heat transfer in heat exchangers, and corrosion of metal materials. In membrane separation, which filters liquids such as river water, seawater, and activated sludge, the organic polymers of the extracellular polysaccharides in the biofilm released into the water phase cause membrane clogging. Non-patent document 1.

[0003] Bacteria growing in biofilms are more resistant to antibacterial agents than planktonic bacteria, and once formed, they are not easily removed. Biofilms attached to solid surfaces and released into the aqueous phase in this way both cause the various problems mentioned above.

[0004] Regarding such problems, for example, Non-Patent Document 1 states that in any biofilm problem, methods of directly attacking or removing the biofilm have not been successful, and states that an effective measure is to prevent bacteria from adhering to solid surfaces.

[0005] In addition, the international standard ISO22196 for evaluating the antibiofilm performance of solid surfaces is often used for the evaluation of antibiofilm performance, but it has been pointed out that this is incorrect. A new international standard proposal for the evaluation of antibiofilm processed products has been announced. Non-patent document 2. There is an urgent need to develop antibiofilm agents and processing methods using them. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5698336 [Patent Document 2] Patent No. 5851934 [Patent Document 3] Patent Publication No. 2021-116483 [Patent Document 4] Patent No. 5723076 [Patent Document 5] Patent No. 5787566 [Non-patent literature]

[0007] [Non-Patent Document 1] Karin Sauer (Professor of Biology at the State University of New York, Associate Director of the Binghamton Biofilm Research Center) Nikkei Science 2018 03 P68~P73 "Destroying Biofilms" Original title The War on Slime (SCIENTIFIC AMERICAN November 2017) Karin Sauer [Non-Patent Document 2] Author: Naoki Nakatsugawa (SIAA Biofilm Committee Surface Technology Vol. 72. No. 5 2021 P287-P289 "Toward the establishment of a certification system for anti-biofilm processed products" Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide an agent having anti-biofilm function (function of inhibiting biofilm formation on a solid surface) and whose function lasts, and a processing method in which the function lasts. (1) Anti-biofilm agents that prevent bacteria from adhering to solid surfaces rather than attacking the bacteria. (2) An anti-biofilm agent whose anti-biofilm function lasts for a long period of time. (3) A processing method that prevents the anti-biofilm agent from dissolving or being depleted. [Means for solving the problem]

[0009] The inventors were inspired by Non-Patent Document 1, which states that "to prevent bacteria from adhering to a solid surface, it is not necessarily necessary to prevent the adhesion of the bacteria themselves, but it is also possible to inhibit the proteins used as a foothold for bacterial adhesion," and arrived at the present invention based on the following concept. An inorganic anti-biofilm agent having a catalytic function of generating active oxygen is dispersed inside, for example, a thermoplastic resin molded body (processed member). The active oxygen passes between the resin molecules, reaches the surface of the thermoplastic resin molded body, and denatures the proteins that serve as a foothold for bacterial adhesion, preventing bacterial adhesion and inhibiting the formation of a biofilm. The composite metal oxide anti-biofilm agent shown in the examples does not dissolve to the outside of the processed member, and therefore the anti-biofilm agent does not become depleted. The present invention includes the following inventions. (1) A composition of inorganic particles having an average primary particle size of 0.01 to 0.1 μm and represented by the following general formula (1), characterized in that the particle size distribution on a volume basis of the inorganic particles (secondary particles) in the composition dispersed in water has a particle diameter D50 (median diameter) at which the cumulative frequency is 50% of the total of the inorganic particles (secondary particles) in the composition is 0.02 to 0.05 μm. (ZnO)x(Al2O3)1-x (1) (wherein x is 0.5≦x<0.995) (2) The composition of inorganic particles according to (1) above, characterized in that the inorganic particles in the composition have a particle size distribution on a volume basis, the particle size D90 (median size) at which the cumulative frequency is 90% being 0.03 to 0.06 μm. (3) The inorganic particle composition according to (1) or (2) above, characterized in that the content of the organic solvent is 0.5 to 60% by volume. (4) An anti-biofilm agent comprising a composition of inorganic particles according to any one of (1) to (3) above. (5) An anti-biofilm agent-non-eluting anti-biofilm resin molded article and an anti-biofilm food packaging method using any one of the compositions (1) to (3) above. (6) An anti-biofilm paint that does not release an anti-biofilm agent, and a coating method thereof, which uses any one of the compositions (1) to (3) above. (7) A method for processing anti-biofilm fibers without eluting an anti-biofilm agent, using any one of the compositions (1) to (3) above. (8) An anti-biofilm wood preservative using any one of the compositions (1) to (3) above, and a processing method thereof. (9) An anti-biofilm medical instrument and an anti-biofilm medical device, which use any one of the compositions (1) to (3) above and from which an anti-biofilm agent is not eluted. Effect of the Invention

[0010] According to the present invention, it is possible to provide an anti-biofilm agent and a method for preventing bacterial adhesion using an anti-biofilm agent that can provide a good bacterial adhesion prevention effect against various bacterial species and on solid surfaces made of various materials. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiment of the present invention will be described in detail. Note that the present invention is not limited to the following embodiment, and can be modified in various ways within the scope of the present invention.

[0012] (Bacteria adhesion prevention agent and processing method using same) In the present invention, (a) (ZnO)x(Al2O3)1-x is selected as an active oxygen generating catalyst. Its characteristic is that it generates active oxygen regardless of the presence or absence of light. When dispersed in a resin, it does not dissolve from the resin and is not consumed. (b) In the volume-based D90 (median diameter) of the secondary particle diameter of the aqueous dispersion of (ZnO)x(Al2O3)1-x, the size of the secondary particle diameter is set to 100 nm or less to activate the generation of active oxygen. The active oxygen penetrates the resin and reaches the resin surface, preventing bacteria from adhering to the surface, inhibiting the formation of biofilms, and adding an anti-biofilm function to the product. Patent Document 1 and Patent Document 2 are inventions about antibacterial functions. They are not anti-biofilm functions. EXAMPLES

[0013] The present invention will be described in more detail with reference to examples, but it should be understood that the present invention is not limited to these examples.

[0014] (Example 1) <Synthesis of composite metal oxide> The inorganic particles used in the present invention are compounds represented by the following general formula (1). 0.5≦x<0.995, more preferably 0.7≦x<0.98, and even more preferably 0.85≦x<0.97. If x is too large, the inorganic particles will aggregate in the composition and the total surface area will decrease, and if x is too small, the effect of imparting functionality will decrease, which is not preferable. The inorganic particles can be produced by the method described in U.S. Patent No. 5,741,526. (ZnO)x(Al2O3)1-x (1) (In the formula, x is 0.5≦x<0.995) The average primary particle size of the zinc oxide aluminum solid solution (the composite metal oxide) is 0.01 to 0.05 μm. Primary particles refer to independent particles without aggregation. The average size of the primary particles is 0.01 to 0.1 μm, and more preferably 0.01 to 0.03 μm. If the average primary particle size is too large, the specific surface area decreases, and the functional effect is reduced.

[0015] Photographs are taken at a magnification of 100,000 times using a transmission electron microscope and printed at a total magnification of 500,000 times. 500 particles are randomly selected and their outlines are traced with a digitizer to obtain the particle size. The arithmetic mean value of these particle sizes is taken as the average primary particle size of the inorganic particles.

[0016] Example 2 The zinc aluminum oxide solid solution was dispersed in water, and a composition containing both fine particles (100 nm to 10 μm) and nanoparticles (100 nm or less) was prepared using a wet bead mill method.

[0017] The present inventors have developed an inorganic particle composition characterized in that the particle diameter D90 (median diameter) at which the cumulative frequency is 90% in a volume-based particle size distribution is 5 nm to 100 nm, for the obvious reason that the greater the proportion of nanoparticles in the inorganic particle composition, the greater the total surface area of ​​the particles in the composition, i.e., the greater the functionality.

[0018] The inorganic particle composition was obtained by changing the temperature during the preparation of the composition, the stirring conditions, the amount of the preparation liquid, the conditions when adding water, and the stirring method and strength. The particle size of the inorganic particles in the composition can be measured by a laser diffraction / scattering method.

[0019] The solvent of the composition is preferably water, but mixing an organic solvent with water makes it easier to control the volumetric D90 of inorganic particles.The organic solvent is preferably methanol, ethanol, isopropanol, 1-propanol, 1-butanol, tert-butyl alcohol, allyl alcohol, 1-octanol, 2-ethylhexanol, cyclohexanol, n-hexanol, etc. alcohols, N,N-dimethylacetamide, acetylacetone, acetone, aniline, ethanolamine, ethylene glycol, glycerin, p-chlorotoluene, dimethylsulfoxide, triethanolamine, methyl ethyl ketone, cyclohexane, hexane, heptane, n-octane, n-decane, butyl acetate, hexyl acetate, isooctane, cyclohexane, toluene, etc.Methanol, ethanol, isopropanol, 1-propanol, 1-butanol, tert-butyl alcohol, etc. alcohols, N,N-dimethylacetamide are more preferred. The content of the organic solvent is preferably 0.5 to 30% by volume, more preferably 5 to 20% by volume, and even more preferably 5 to 10% by volume. If the content of the organic solvent is too small, the variation in the area median diameter becomes large, and if it is too large, the inorganic particles tend to aggregate and settle, which is not preferable.

[0020] The concentration of aluminum ions (hereinafter referred to as Al ions) in the solvent of the composition is preferably 15 ppm or less, more preferably 10 ppm or less, and even more preferably 3 ppm or less. The water used on-site contains Al ions because an aluminum-based coagulating and precipitating agent is used. Al ions are not preferred because they promote the coagulation of the inorganic particles, making it difficult to control the particle size. The Al ion concentration is obtained by centrifuging the composition and measuring the filtered solvent by atomic absorption spectrometry.

[0021] When dispersing the inorganic particles in water, it is preferable to use an anionic, nonionic, amphoteric or cationic surfactant. From the viewpoint of dispersion stability, anionic and nonionic surfactants are preferred, and anionic surfactants are most preferred.

[0022] The pH of the composition is preferably 6.5 to 11.5, more preferably 7.0 to 11, and even more preferably 8.0 to 10.5. If the pH is too low, the dispersibility of the inorganic particles deteriorates, causing the particles to aggregate and settle, whereas if the pH is too high, it is undesirable since it can cause skin disorders during handling.

[0023] (1) The composition can be used to impart anti-biofilm properties to food packaging materials, improving food preservation. In this case, the anti-biofilm agent does not dissolve into the food (non-dissolution method). The composition continues to generate active oxygen, inhibiting food spoilage for a long period of time, and can also prevent or reduce the addition of food preservatives and taste-adjusting additives to food. In addition, in aseptic food filling and packaging, the heat sterilization temperature before or after filling can be lowered, or the sterilization time can be shortened, improving the taste of processed foods. As a result, the number of steps in the aseptic filling and packaging can be reduced, the expensive equipment costs can be reduced, and the time required for the aseptic filling and packaging can be shortened. The reason for this is that, while the conventional method does not have an anti-biofilm function that inhibits biofilm formation in the packaging material, the present invention has a sustained anti-biofilm function and does not dissolve the anti-biofilm agent into the contents.

[0024] <Non-elution method 1> When the inorganic nanoparticles are dispersed in a resin substrate layer that comes into contact with food, the inorganic fine particles do not migrate through the resin and are not exposed on the surface of the resin substrate layer. In addition, when the inorganic particles are added to a resin and the resin is molded by heat melt processing, a skin layer without inorganic particles is always formed. Therefore, the inorganic particles do not come into contact with food, and the generated active oxygen reaches the surface of the resin substrate layer, thereby exerting antibacterial and antibiofilm activity. The shelf life of food can be improved without dissolving the antibiofilm agent into the food.

[0025] <Non-elution method 2> It is suitable for the purpose of completely dispelling the anxiety of consumers who are concerned about the elution of antibiofilm agents into food, or for legal applications (e.g. milk) where the presence of antibacterial agents and antibiofilm agents is prohibited in layers that come into contact with food (including beverages). A shielding resin layer without inorganic particles may be provided between the food and a resin, paper, limestone, or a mixture thereof in which the inorganic nanoparticles are present. Active oxygen permeates the shielding resin layer to exhibit antibiofilm activity. The shelf life of food can be improved. A plastic film can be used for the shielding layer. The plastic film is preferably an olefin resin such as polyethylene or polypropylene, a polyester such as polyvinylidene chloride or polyethylene terephthalate, or a silicone resin, more preferably polyethylene, polypropylene, polyethylene terephthalate, or a silicone resin, and most preferably polyethylene or polypropylene. The substrate is not limited to paper or plastic. Substrates include metal, calcium carbonate, or a mixed substrate of calcium carbonate and resin. The substrate may or may not contain the inorganic particles.

[0026] Example 3 30g of chicken breast meat was mixed with 30cc of distilled water, sealed in a bag sterilized at 80℃, thoroughly kneaded, and the liquid portion was sealed in each bag. It was then placed in a 36℃ environment, and the number of Staphylococcus aureus bacteria was measured after 18 hours, and an evaluation was conducted in which it was compared with a blank. The following effects were confirmed. The global research goal is to reduce bacterial growth to 1 / 100 of the blank. However, this has not yet been achieved. <Non-elution method 1> Sample 1, <Non-elution method 2> Sample 2 Anti-biofilm agents and food anti-biofilm packaging (film) were evaluated, with the results shown in the table below. [Table 1]

[0027] (Confirmation of sustained generation of active oxygen) The antibiofilm agent of the present invention was dispersed in a polyethylene film at a weight ratio of 0.5%, and the antibacterial activity value of the film surface was measured. The phenomenon that the antibiofilm agent of the present invention continues to emit active oxygen was confirmed by the following test method and its results. The following JIS Z280 evaluation method indirectly proves that the antibiofilm performance is sustained. It can be seen that the number of floating bacteria is suppressed by the antibiofilm performance. Antibacterial test method JIS Z2801 E. coli First antibacterial activity value: 3.6 - Antibacterial activity value of the second measurement (60 days after the first measurement): 3.2 From the above results, it was confirmed that active oxygen is continuously generated. The performance duration of anti-biofilm processing is preferably, for example, 7 to 30 days for food packaging and 30 to 45 days for urinary catheters.

[0028] (2) The anti-biofilm agent of the present invention can be kneaded into fibers (including nonwoven fibers) to produce anti-biofilm fibers. The advantage of the present invention is that in addition to imparting anti-biofilm functionality, the anti-biofilm agent is not exposed on the fiber surface, and the anti-biofilm agent can be prevented from accumulating in the nozzle that forms the fibers, preventing the fibers from breaking during formation. Furthermore, as shown in Example 4, the problem can be completely solved by forming a double structure.

[0029] Example 4 The fiber is made into a double structure of an outer layer and an inner layer, and the composition of the present invention is kneaded and dispersed in the inner layer. The anti-biofilm agent of the present invention is not exposed on the fiber surface, and imparts an anti-biofilm function to the fiber surface. Patent Document 3 is an invention related to antibacterial fibers, but is not an invention related to the anti-biofilm of the present case.

[0030] (3) The composition can be incorporated into a paint and then applied to impart an anti-biofilm function. The paint is preferably an aqueous acrylic emulsion, an aqueous PVC emulsion, a water-soluble acrylic, a water-soluble alkyd, a water-soluble urethane paint, or an aqueous silicone paint.

[0031] (4) The composition is impregnated into or applied to wood to prevent decay of the wood caused by bacteria. In addition, termites eat the decayed wood on which the composition remains, killing the intestinal bacteria of the termites and causing the termites to die, thereby preventing damage to the wood by termites. The present invention is effective as a wood preservative. The antibacterial agent described in Patent Document 3 is less effective at inhibiting biofilm growth. The composition of the present invention, which substantially maximizes the proportion of nanoparticles (0.1 μm or less), actively generates active oxygen, providing a sustained anti-biofilm effect that can prevent damage caused by termites. Patent Document 4 is not an invention related to an anti-biofilm agent.

[0032] (5) Biofilms of resistant bacteria form on the inside and outside surfaces of medical catheters (plastic tubes), which are the main cause of hospital-acquired infections. Conventionally, the solution has been to use antibacterial agents, but this has the following problems: (1) Antibacterial agents leach out of the resin tube and cause harm to human health. (2) The antibacterial effect is lost within a short period of time. (3) Antibacterial agents are not very effective in preventing biofilms. The composition can be used to produce an anti-biofilm medical catheter that does not release the anti-biofilm agent and is effective for a long period of time (30 days or more).Patent Document 5, which shows the prior art, does not include any measures against biofilms. Patent Document 4 is an invention relating to an antibacterial catheter, which is different from an anti-biofilm catheter.

[0033] Biofilms are almost always present where solid surfaces come into contact with water. A biofilm is a community of microorganisms that adsorb to a solid surface and produce extracellular polysaccharides and then enter the matrix. In the following, the term "bacteria" will be used to represent microorganisms. Problems caused by biofilms include biofilm contamination of food packaging, food preparation utensils, cooking environments, medical equipment, medical catheters, and medical environments, as well as increased frictional resistance of fluids in water pipes and ship bottoms, reduced heat transfer in heat exchangers, and corrosion of metal materials. In membrane separation, which filters liquids such as river water, seawater, and activated sludge, the organic polymers of extracellular polysaccharides in biofilms released into the water phase cause membrane clogging. In the past, various efforts have been made to use antibacterial agents to combat biofilms, but it has become clear that antibacterial agents are ineffective in combating biofilms, and new international evaluation standards for antibiofilm function have been approved. This invention will contribute to solving biofilm problems in a wide range of fields. [Industrial Applicability]

[0034] Anti-biofilm functional packaging for food, anti-biofilm cookware to prevent food poisoning, anti-biofilm paints, prevention of hospital infections (paints, equipment, catheters), biofilm countermeasures for liquid supply pipes, ship bottom paints, seawater desalination, and measures to prevent clogging of activated sludge filters, etc.

Claims

1. The composition comprises inorganic particles having an average primary particle size of 0.01 to 0.1 μm and represented by the following general formula (1), wherein the inorganic particles (secondary particles) in the composition dispersed in water have a particle size distribution on a volume basis in which a particle diameter D50 (median diameter) at which a cumulative frequency reaches 50% is 0.02 to 0.05 μm: (ZnO)x(Al2O3)1-x (1) (In the formula, x is 0.5≦x<0.995)

2. 2. The composition of inorganic particles according to claim 1, wherein the inorganic particles in the composition have a particle size distribution on a volume basis, the particle size D90 (median size) at which the cumulative frequency is 90% is 0.03 to 0.06 μm.

3. 3. The composition of inorganic particles according to claim 1, wherein the content of the organic solvent is 0.5 to 60% by volume.

4. An anti-biofilm agent comprising a composition of inorganic particles according to any one of claims 1 to 3.

5. An anti-biofilm agent-non-eluting anti-biofilm resin molded product and an anti-biofilm food packaging method using the composition according to any one of claims 1 to 3.

6. An anti-biofilm paint that does not release an anti-biofilm agent, and a coating method thereof, which uses the composition according to any one of claims 1 to 3.

7. A method for processing anti-biofilm fibers without eluting an anti-biofilm agent, using the composition according to any one of claims 1 to 3.

8. An anti-biofilm wood preservative using the composition according to any one of claims 1 to 3, and a method for processing the same.

9. An anti-biofilm medical instrument and an anti-biofilm medical device, in which an anti-biofilm agent using the composition according to any one of claims 1 to 3 is not eluted.

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