JP2008284312A - Pathogenic microorganism sterilization method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pathogenic microorganism sterilization method by which a pathogenic microorganism is easily sterilized while safety for human body is maintained without using ultraviolet light and blending titanium oxide. <P>SOLUTION: The pathogenic microorganism sterilization method is provided in which a composition containing an oxidizing agent is brought into contact with an object and the object is irradiated with light beams including light having a single or a plurality of wavelengths within the range of 400-1,000 nm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for killing pathogenic microorganisms.

The present invention relates to a method for killing pathogenic microbes. More specifically, for example, on the surfaces of teeth, gums, oral mucosa, dentures, denture bases, crown restoration materials, orthodontic beds, wires, bridges, etc., causes of oral diseases represented by dental caries and periodontal diseases The present invention relates to a method for killing pathogenic microorganisms that can be easily killed while maintaining safety to human bodies.
Here, a pathogenic microbe refers to a microbe that causes disease such as bacteria and viruses.

  In the dental field, high-concentration hydrogen peroxide or hypochlorous acid is used as a method for sterilizing oral bacteria such as mutans bacteria. However, when these bactericides are used at high concentrations, they have side effects such as lipid oxidation and protein degeneration in normal tissues, and tissue destruction.

  Moreover, the technique described in patent document 1 is known as a sterilization technique using hydrogen peroxide. In this technology, the inside of a food packaging container is attached using a low-density hydrogen peroxide-containing solution, sterilized in a short time by the synergistic effect of the sterilizing agent attachment and ultraviolet irradiation, and by blowing an inert gas. It removes hydrogen peroxide as soon as possible. In Patent Document 1, “the hydrogen peroxide-containing solution (sterilizing agent) is a hydrogen peroxide-containing solution having a low concentration of about 0.01 to 0.5% by weight, preferably about 0.1%. It is said.

  In general, a titanium dioxide photocatalyst exhibits a photocatalytic activity in response to ultraviolet rays of 380 nm or less, but it is not preferable to irradiate the human body with such ultraviolet rays.

  On the other hand, in Patent Document 2, a dental sterilizing composition comprising a mixture containing titanium dioxide and a hydrogen peroxide solution or a compound that generates hydrogen peroxide when made into an aqueous solution is applied to the surface of the coated body, A dental sterilization method characterized by irradiating visible light having a wavelength of 500 nm. Is described.

This technique irradiates visible light including a wavelength of 380 to 500 nm, and attempts to solve the problem of Patent Document 1.
However, in Patent Document 2, it is considered that sterilization is performed by the following action. “When the titanium dioxide photocatalyst is irradiated with light, electrons, electrons and holes are generated, which react with hydrogen peroxide to generate active oxygen. This active oxygen has a much stronger oxidizing power than ozone and can oxidize and decompose almost all organic substances to carbon dioxide. ]

In Patent Document 2, active oxygen (superoxide: O ₂ ⁻ ) is the essence of bactericidal action, and for that purpose, titanium oxide is essentially blended. However, in order to mix titanium oxide, titanium oxide must be dispersed in a medium to form a sol. In addition, the technique described in Patent Document 2 cannot be used when an object to be killed by pathogenic microorganisms is desired to avoid contamination with titanium oxide.

Patent Document 2 only describes light irradiation only in the ultraviolet region, and does not describe light irradiation having a wavelength in the infrared region at all.
JP 2004-59014 A JP 2004-323417 A

  The present invention provides a method for killing pathogenic microorganisms that can easily kill pathogenic microorganisms while maintaining safety to the human body without using ultraviolet rays and without compounding titanium oxide. For the purpose.

  The invention according to claim 1 is a pathogenic microorganism that contacts an object with a composition containing an oxidant and irradiates the object with a light beam having light having a single wavelength or a plurality of wavelengths in the range of 400 nm to 1000 nm. It is a killing method.

  The invention according to claim 2 is a method for killing pathogenic microorganisms in which the oxidizing agent is hydrogen peroxide or hypochlorous acid.

  The invention according to claim 3 is the method for killing pathogenic microorganisms according to claim 1 or 2, wherein 1 μM or more of hydroxyl radicals are generated.

  The invention according to claim 4 is the method for killing pathogenic microorganisms according to any one of claims 1 to 3, wherein a light beam including light having a single wavelength or a plurality of wavelengths in the range of 700 nm to 1000 nm is irradiated. .

  The invention according to claim 5 is the method for killing pathogenic microorganisms according to any one of claims 1 to 4, which irradiates a light beam including light having a single wavelength or a plurality of wavelengths in a range of 350 nm to 500 nm.

  The invention according to claim 6 is the method for killing pathogenic microorganisms according to any one of claims 2 to 5, wherein the concentration of hydrogen peroxide is 3% by weight or less.

  The invention according to claim 7 is the method for killing pathogenic microorganisms according to any one of claims 2 to 5, wherein the concentration of hypochlorous acid is 3% by weight or less.

  The invention according to claim 8 is the object according to any one of claims 1 to 7, wherein the object is any one of a tooth, a gum, an oral mucosa, a denture, a denture base, a dental restoration material, an orthodontic floor, a wire, and a bridge. 2. A method for killing pathogenic microorganisms according to item 1.

  The invention according to claim 9 is the method for killing pathogenic microorganisms according to any one of claims 1 to 7, wherein the object is a food product.

  The invention according to claim 10 is the method for killing pathogenic microorganisms according to any one of claims 1 to 7, wherein the object is water.

  The invention according to claim 11 is the method for killing pathogenic microorganisms according to any one of claims 1 to 10, wherein the light beam is a laser beam.

  The invention according to claim 12 is the method for killing pathogenic microorganisms according to claim 11 in which the light beam is irradiated as pulsed light.

  The invention according to claim 13 is the method for killing pathogenic microorganisms according to any one of claims 1 to 12, wherein the light beam is irradiated for 25 seconds or more.

  In the invention according to claim 14, hydrogen peroxide or hypochlorous acid is brought into contact with or contained in an unexposed portion of the object, and light is irradiated from the surface of the object. The method for killing pathogenic microorganisms described in the item.

The invention according to claim 15 is the method according to any one of claims 1 to 14, wherein the object is brought into contact with an oxidant at a place other than the installation place, and then the object is placed at a predetermined place to irradiate the light beam. A method for killing pathogenic microorganisms as described.
(Function)

The operation and embodiment of the present invention will be described below together with the knowledge obtained in making the present invention.
The present inventor has examined a method for combining light irradiation with an oxidizing agent (hydrogen peroxide, hypochlorous acid) as a method for sterilizing infectious diseases (commonly called caries) in the lumen. In the hydrogen peroxide sterilization method, it is known that the sterilization efficiency is increased by irradiating ultraviolet rays or the like.
However, it is known that irradiating eyes or mucous membranes with high-power laser light may cause injury. Therefore, it is not preferable to use laser light in the ultraviolet region (186, 254, 386 nm).

Therefore, it was decided to verify the bactericidal effect by using light having a wavelength close to visible light or a wavelength in the infrared region, which is relatively safe.
In conducting the verification, the present inventor has obtained the following knowledge.

  First, it was found that a bactericidal effect occurs without using titanium oxide. Accordingly, the present invention substantially does not contain titanium oxide. Even if it is contained, only the amount below the content required in Patent Document 2 is used. Therefore, only hydrogen peroxide or hypochlorous acid is sufficient as a chemical. As a result, the contact of chemicals by application to the object is extremely simple.

  Next, it was found that hydroxyl radicals are greatly involved in the bactericidal effect, and that the concentration has a critical value. That is, it was found that the bactericidal effect rapidly increases when the hydroxyl radical is 10 μM or more.

Furthermore, Patent Document 2 considers that sterilization is performed by active oxygen (superoxide: O ₂ ⁻ ). Therefore, titanium dioxide is essentially blended in order to generate active oxygen from hydrogen peroxide. However, the present inventor has found that killing of pathogenic microorganisms is strongly performed by hydroxyl radical (OH.), And the hydroxyl radical emits a light beam having a predetermined wavelength from hydrogen peroxide or hypochlorous acid. It was found that it can be generated by irradiation.

  And it discovered that generation | occurrence | production of the hydroxyl radical was recognized also by irradiating the light which has a wavelength in an infrared region. Note that none of the patent documents suggests irradiation of light having a wavelength in the infrared region. There is no description suggesting irradiation in the infrared region that it can be used for the sterilization and sterilization of pathogenic microorganisms in the lumen and is useful for the treatment of dental areas and the prevention of infectious diseases.

  Examples of the light source used in the present invention include exothermic lamps, fluorescent lamps, halogen lamps, black lights, metal halide lamps, xenon lamps, mercury lamps, UV lamps, LEDs (light emitting diodes), and semiconductor lasers. In the case of a single wavelength, the surface obtained by contacting the light from these light sources with an antibacterial agent after guiding unnecessary light through an appropriate filter and then guiding the light through an appropriate means. May be sterilized by irradiation. The light used is not limited to a single wavelength. Light having a plurality of wavelengths may be used.

  In the present invention, a light beam including light having a single wavelength or a plurality of wavelengths in the range of 380 nm to 1000 nm is used. If it is less than 380 nm, the human body may be damaged. On the other hand, when it exceeds 1000 nm, generation of sufficient hydroxyl radicals may not be achieved.

  In the lower region (region near the ultraviolet ray), 380 to 500 nm is preferable, and 400 to 420 nm is more preferable. In the upper region (region near infrared), 750 to 1000 nm is preferable, and 800 to 900 nm is more preferable. In the range of 800 to 900 nm, the generation amount of hydroxyl radicals is remarkably increased as compared with other ranges.

In the present invention, an object is brought into contact with a composition containing an oxidizing agent.
As the oxidizing agent, hydrogen peroxide and hypochlorous acid are preferably used. These oxidizing agents can easily generate hydroxyl radicals necessary for sterilization compared to other oxidizing agents. There is no need to include titanium oxide in the composition. However, not all cases are excluded. Even if it is included, the case where the content required in the wavelength used in Patent Document 2 matches is excluded.

When the relationship between the amount of hydroxyl radicals and the bactericidal effect was examined, when the amount of hydroxyl radicals present exceeded 10 μm, the bactericidal effect suddenly occurred.
Control of the amount of hydroxyl radicals is proportional to the irradiation time of the light beam. That is, the generated hydroxyl radicals are accumulated without disappearing and increase linearly as the irradiation time increases. Accordingly, the amount of hydroxyl radicals accumulated may be controlled by controlling the irradiation time.

  Depending on the wavelength to be irradiated and the concentration of the oxidizing agent, generally, an increase in hydroxyl radicals of 0.5 μM to 10 μM or 1 μM to 10 μM is achieved by irradiation for 1 minute. The thinner the oxidant concentration, the less hydroxyl radicals are generated. Therefore, the irradiation may be longer when the density is low than when the density is high. In addition, about 5 μM of hydroxyl radicals may exist even before light irradiation. Therefore, for example, in order to achieve a sterilization effect of 10 μM, 5 μM may be generated. What is necessary is just to obtain the irradiation time under each individual condition.

In the present invention, the concentration of hydrogen peroxide or hypochlorous acid is preferably 3% by weight or less. By setting it to 3% by weight or less, the influence on the object can be reduced. Moreover, even if it is 3 weight% or less, the amount of hydroxyl radicals required for sterilization can be generated.
In addition, as a minimum, 0.01 weight is preferable. If it is less than 0.01% by weight, it may take a long time to generate hydroxyl radicals.

  In order to bring a composition containing hydrogen peroxide or hypochlorous acid into contact with an object, the composition may be applied to the object. Or what is necessary is just to immerse in the solution (solution which melt | dissolved the composition in the pure water and the electrolysis water) of the composition. You may make it contain in the inside of a target object. When it is contained inside, it may be mixed in the material of the object. In addition, a chemical may be disposed in a portion that is invisible from the outside and that can be irradiated with a light beam to be irradiated.

  In the present invention, examples of the object include teeth, gums, oral mucosa, dentures, denture bases, dental crown restoration materials, orthodontic beds, wires, bridges and the like. An object integrated with an animal in an animal is also included. However, humans are excluded from animals in countries that are not subject to protection when in the human body.

When it is desired to irradiate light of a specific wavelength, when it is desired to irradiate light of high energy locally, when it is desired to irradiate light limited to a very narrow region, laser light is preferably used.
In particular, in the present invention, by using laser light, it is possible to locally irradiate high energy light and generate many hydroxyl radicals in a short time.

  The light irradiation time may be appropriately adjusted according to the degree of sterilization, but when it includes a wavelength in the range of 700 nm to 1000 nm, it depends on the intensity of light, but is preferably 25 seconds or more. From the viewpoint of generation of hydroxyl radicals, 1 minute or more is preferable, and 5 minutes or more is more preferable. When the time is 20 seconds or longer, it is possible to generate hydroxyl radicals necessary for sterilization in a short time (thus, without unexpectedly damaging the object or its surrounding objects). In the case of other wavelengths, 1 minute or longer is preferable, and 5 minutes or longer is more preferable. Moreover, it is preferable to irradiate a laser beam.

  Hydrogen peroxide or hypochlorous acid may be brought into contact with or contained in the non-exposed portion of the object, and light may be irradiated from the surface of the object. That is, an oxidizing agent is applied to a portion where light cannot be directly irradiated (for example, the back side of the object), and light is irradiated from the surface. If the object is formed of a material having transparency for a specific wavelength, the irradiated light passes through the object and reaches the back surface, where it generates hydroxy radicals. Not only the back side but also the inside may be used. In this case, a combination of a specific wavelength and a material having transparency to the wavelength may be selected as appropriate.

  In particular, it is preferably used in the case of an object to be removed and moved from a specific place. For example, in the case of a tooth bridge, an oxidizing agent is applied to the bridge in a detached state. Then, when attached to the oral cavity, a part of the bridge becomes a shadow of gums. When infrared rays are irradiated from the surface of the gingiva, it becomes possible to generate hydroxyl radicals even in the shadow portion through the gingiva.

According to the present invention, the following effects are achieved.
By combining a visible light laser or infrared laser and an oxidizing agent (hydrogen peroxide, hypochlorous acid), pathogenic microorganisms can be killed safely and efficiently.
For example, in combination with hydrogen peroxide (1M) used in dentistry, it is expected to sterilize the cavity in a short time.

  In conventional oral sterilization, only sterilization within the range where the oxidant reaches is possible, but in the method of the present invention, sterilization within the range through which light is transmitted is possible. As a result, injury to normal tissue can be reduced, and pain associated with sterilization can be reduced.

In this example, two types of hydrogen peroxide solutions of 1M and 0.1M are irradiated with a laser diode (LD) (405 nm) at a maximum output (17.5 mW) from a distance of 90 mm, and an ESR spectrum observed. I investigated.
The measurement of the hydroxyl radical was performed by measuring the hydroxyl radical generated by light irradiation of two types of laser diodes using the ESR single spin trapping method.

Details are described below.
(1) Hydrogen peroxide solution (30%: 10M) purchased from Wako Pure Chemicals was prepared. Here,% is% by weight (the same applies hereinafter).
This hydrogen peroxide solution was diluted to 1M (3%) and 0.1M (0.3%) with pure water.

(2) 200 μL each of 1 M hydrogen peroxide solution and 0.1 M hydrogen peroxide solution were put into an eppendle / centrifuge tube (sample tube). At that time, spin trapping agent (radical scavenger) DMPO 20 μL (0.8 M) was added and stirred for 10 seconds.
DMPO is 5,5-Dimethyl-1-pyrrolin-N-oxide, and in this example, a product manufactured by Labotech (Tokyo) was used.

(3) The sample tube was fixed, and the upper part (90 mm, 150 mm) of the sample tube was irradiated with a laser diode (LD) for 1-5 minutes.
The maximum output at that time is 17.5 mW. The wavelength is 405 nm.
As a laser diode (LD) light irradiation device, a visible light laser unit (model SU-61C) manufactured by Pax Corporation was used.
The transmission wavelength was 405 nm, the maximum output was 17.5 mW, and the beam diameter at the time of condensing (irradiation distance 50 mm, 0.025 nm × 0.035 nm).

(4) After LD irradiation, about 130 μL of the solution was sucked into a quartz cell for an ESR-dedicated aqueous solution, and recording of an ESR spectrum was immediately started by an electron spin resonance apparatus (JEOL, JES-FA100). The ESR apparatus measurement conditions are shown below.
Resonance frequency: 9.427 GHz
Output: 4.0mW
Magnetic field modulation: 100 kHz
Observation magnetic field: 335.500 ± 5 mT
Measurement time: 2 minutes Modulation width: 0.1 mT
Amplification factor: 300

(5) An ESR spectrum of a spin radical (DMPO-OH) derived from a hydroxyl radical as shown in FIG. 1 was observed from a 1 M hydrogen peroxide solution. FIG. 1 suggests that hydroxyl radicals are generated in the hydrogen peroxide solution. The observed signal was a hydroxyl radical, using the hyperfine splitting constant of the ESR spectrum.
That is, the hyperfine splitting constant of the observed ESR spectrum was found to be hfcc, aN = aH = 1.49 mT, and this signal was attributed to DMPO-OH. Furthermore, from the area of the ESR spectrum, the concentration of DMPO-OH was determined to be 20 μM.
In the sterilization, if the hydroxyl radical is present in an amount of 10 μM or more, the sterilization / sterilization action occurs. Therefore, it can be seen that the present example can be sterilized / sterilized.

In this example, the experiment was performed by changing the irradiation time of the laser beam. That is, the light irradiation time dependence of hydroxyl radical generation was examined.
The other points were the same as in Example 1.
The result is shown in FIG.
In FIG. 2, the case where □ is 1M and the case where ◆ is 0.1M are shown.
An increase in signal intensity (DMPO-OH) depending on concentration and irradiation time was observed.
Further, even in the case of 0.1M, generation of hydroxyl radical was observed.

This example is an example in the case of irradiating infrared light of 805 nm.
Irradiation with 805 nm infrared light was performed by adding 990 μL and DMPO 10 μL to a glass cell (diameter 30 mm, depth 5 mm).
In addition, the Unitak Co., Ltd. product was used for the laser irradiation apparatus using infrared light.
The other points were the same as in Example 2. The concentration of hydrogen peroxide was 1M.

Before light irradiation, the hydroxyl radical was 5 μM. Upon irradiation with light, the hydroxyl radicals increased linearly by 2 μm per 10 seconds. In order to generate 10 μM, it was found that irradiation should be performed for 25 seconds or longer.
Irradiation of infrared light (805 nm) to hydrogen peroxide (1M) revealed the generation of hydroxyl radicals. The amount produced was almost the same as that of the visible light laser.

In this example, hypochlorous acid was used instead of hydrogen peroxide.
Similar results were obtained with hypochlorous acid as with hydrogen peroxide.
(Comparative Example 1)

In this example, when a wavelength of 430 nm was used, the amount of hydroxyl radicals generated was much smaller than that in Example 1.
(Comparative Example 2)

  In this example, when wavelengths of 780 nm and 830 nm 4 were used, the amount of hydroxyl radicals generated was very small compared to the case of Example 1.

FIG. 6 is an ESR spectrum diagram according to Example 1 and observed by LD irradiation. The irradiation time is 5 minutes. 6 is a graph showing the irradiation time dependency of DMPO-OH generated by LD (405 nm) irradiation according to Example 1; It is a graph which concerns on Example 2 and shows the irradiation time dependence of DMPO-OH produced | generated by LD (805 nm) irradiation.

Claims (15)

A method for killing pathogenic microorganisms, wherein a composition containing an oxidizing agent is brought into contact with an object, and the object is irradiated with light containing light having a single wavelength or a plurality of wavelengths in the range of 400 nm to 1000 nm. The method for killing pathogenic microorganisms according to claim 1, wherein the oxidizing agent is hydrogen peroxide and / or hypochlorous acid. The method for killing pathogenic microorganisms according to claim 1 or 2, wherein 1 µM or more of hydroxyl radicals are generated. The method for killing pathogenic microorganisms according to any one of claims 1 to 3, wherein a light beam containing light having a single wavelength or a plurality of wavelengths in the range of 700 nm to 1000 nm is irradiated. The method for killing pathogenic microorganisms according to any one of claims 1 to 3, wherein a light beam containing light having a single wavelength or a plurality of wavelengths in the range of 350 nm to 500 nm is irradiated. The method for killing pathogenic microorganisms according to any one of claims 2 to 5, wherein the concentration of hydrogen peroxide is 3 wt% or less. The method for killing pathogenic microorganisms according to any one of claims 2 to 5, wherein the concentration of hypochlorous acid is 3% by weight or less. The pathogenic microorganism according to any one of claims 1 to 7, wherein the object is any one of a tooth, a gum, an oral mucosa, a denture, a denture base, a crown restoration material, an orthodontic floor, a wire, and a bridge. How to kill. The method for killing pathogenic microorganisms according to any one of claims 1 to 7, wherein the object is a food product. The method for killing pathogenic microorganisms according to any one of claims 1 to 7, wherein the object is water. The method for killing pathogenic microorganisms according to any one of claims 1 to 10, wherein the light beam is laser light. The method for killing pathogenic microorganisms according to claim 11, wherein the light beam is irradiated as pulsed light. The method for killing pathogenic microorganisms according to any one of claims 1 to 12, wherein the light beam is irradiated for 25 seconds or more. The pathogenic microorganism according to any one of claims 1 to 13, wherein hydrogen peroxide or hypochlorous acid is contacted or contained in a non-exposed portion of the object, and light is irradiated from the surface of the object. How to kill. The killing of the pathogenic microorganism according to any one of claims 1 to 14, wherein an object is brought into contact with an oxidizing agent at a place other than the place of installation, and then the object is placed at a predetermined place and irradiated with the light beam. Method.

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