Anti-pathogenic agent composed of bio-nano carbon

Abstract

To provide a novel anti-pathogenic agent that needs no excitation means.SOLUTION: The present invention provides an anti-pathogenic agent composed of bio-nano carbon (another name: biochar), which is the bio-nano carbon obtained by carbonizing biomass, wherein the biomass is rice husk, and a mass ratio of silicon oxide to carbon is 5:95 to 20:80. When mixed and fixed in a polymer, the anti-pathogenic agent demonstrates anti-pathogenic effects through a water-soluble medium.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an anti-pathogen agent composed of bio-nanocarbon obtained by burning biomass.

Background Art

[0002] With the pandemic of the novel coronavirus, situations such as a significant shortage of alcohol have occurred, and new means for decontaminating pathogens are required. In particular, in recent years, non-enveloped viruses that are not easily affected by alcohol have often prevailed, so the development of effective anti-pathogen agents against them has become an urgent issue. In particular, since walls and the like always require decontamination, the development of a material having a constant anti-pathogenic property that replaces the spraying of a drug whose effect disappears over time after spraying is desired. Materials in which a metal is supported on a photocatalyst mainly composed of titanium oxide or zeolite have been developed and put into practical use, but excitation means such as light are required, or the effect is only on the surface, so their applications are limited (for example, see Patent Document 1, Patent Document 2, and Patent Document 3). In other words, it can be said that means for constantly removing pathogens are required.

[0003] On the one hand, as the global environment deteriorates with the increase in population, and grains and the like would lead to a large loss of carbon sources if discarded, resource utilization as biomass has been desired (see, for example, Non-Patent Document 1). Among these, biochar produced from residues of grains or wood as raw materials has been tried for use as a soil conditioner, and the goal of improving the carbon cycle has been attempted. Among biochars, those with a particle size in the nanometer range are particularly referred to as bio-nanocarbon (also known as biochar), and various characteristic properties such as magnetism and conductivity may appear from their shape and composition, and have attracted attention. In particular, biochar obtained by burning rice husks contains silicon oxides derived from plant opal, and thus exhibits specific behaviors such as generating heat by microwaves (see, for example, Patent Document 3), and is expected to have a wide range of application fields. However, it is known that adding biochar to soil changes the microbial environment (see, for example, https: / / doi.org / 10.1038 / s41598-022-10682-2 nature.com / scientificreports / ), but its antimicrobial effect is completely unknown. Also, biochar or biochar is a general term for those carbonized using plants, and its structure is a composite of carbon, graphite, graphene, graphene oxide, etc., and sometimes contains additional metals such as silicon, calcium, and magnesium. Biochar (biochar) obtained from gramineous plants usually contains silicon compounds derived from plant opal and is usually referred to as "rice husk silica" regardless of the carbon content. Also, it is known that the biochar obtained by burning rice husks has different contents of silicon sensitizers and carbon forms depending on the treatment method, and its control is important (see, for example, Patent Document 4). In other words, it can be said that its shape, form, and composition greatly affect the properties of biochar.

[0004] That is, the development of a novel anti-pathogen agent that does not require an excitation means, preferably an anti-pathogen agent utilizing biomass, has been desired.

Prior Art Documents

Non-Patent Literature

[0005]

Non-Patent Literature 1

Patent Literature

[0006]

Patent Literature 1

Patent Literature 2

Patent Literature 3

Patent Literature 4

Patent Literature 5

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made under such a background art, and an object thereof is to provide a novel anti-pathogen agent that does not require an excitation means.

Means for Solving the Problems

[0008] In view of such a situation, the present inventors have sought a novel anti-pathogen agent that does not require an excitation means and have made intensive research efforts. As a result, such characteristics have been found in nano-sized biocarbon, leading to the completion of the invention. That is, the present invention is as shown below. In addition, such a novel anti-pathogen agent is also made using biomass. <1> An anti-pathogen agent composed of bio-nanocarbon (alias; biochar) obtained by carbonizing biomass, wherein the biomass is rice husk and the mass ratio of silicon oxide to carbon is 5:95 to 20:80. <2>The antimicrobial agent according to <1>, which exhibits an antimicrobial effect through a water-soluble medium when mixed and fixed with a polymer. <3>The antimicrobial agent according to <1> or <2>, wherein the pathogen is a virus, bacterium or fungus.

Advantages of the Invention

[0009] According to the present invention, a novel antimicrobial agent that does not require a special means can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

[0011] The anti-pathogen agent of the present invention is characterized by comprising bio-nanocarbon (nano-sized biocarbon, synonymous with biocchar). The bio-nanocarbon is characterized by heating and carbonizing biomass, followed by pulverization to adjust the particle size. As the biomass to be used, biomass derived from gramineous plants is preferable, and examples thereof include rice husks and wheat husks such as rice and wheat, and plant bodies after harvesting the fruits. This is because it is preferable for the anti-pathogen agent of the present invention to contain silicon oxides such as silica and silicon carbide in its constituent components, and thus it is preferable to contain glass as plant opal. Based on these, other plant biomass can be appropriately contained within a range where the mass ratio of silicon oxide to carbon is not changed. The bio-nanocarbon, which is the anti-pathogen agent of the present invention, can be obtained by heating such biomass in an electric furnace at 1500 to 4000 ° C, more preferably 2000 to 3500 ° C, for 4 to 12 hours under weakly oxidizing conditions. As the weakly oxidizing conditions, a gas obtained by adding a small amount of oxygen to nitrogen at a mass ratio of 5:95 to 20:80, more preferably 7:93 to 15:85, can be gently supplied as an example. Gentle means leaving it to natural supply or flowing an air current of about 11 / min as an example. Thus, after confirming that the silicon oxide is contained in the equivalent amount in the carbonized crude organism by FTIR, it is pulverized to a particle size of 100 to 500 nm, preferably 150 to 300 nm, using a fine pulverizer such as a jet mill. At this time, if the predetermined amount of silicon oxide is not present, there is a risk of powder explosion, so this point requires attention. When examining the particle size distribution of such bio-nanocarbon, two peaks, that is, a carbon peak and a silicon oxide peak, exist. The silicon oxide peak appears at a smaller side than the carbon peak. The mass ratio of silicon oxide to carbon is 3:97 to 20:80, more preferably 5:95 to 15:85.

[0012] Biochar with such physical properties exhibits excellent anti-pathogenic effects against pathogens such as bacteria, viruses, and fungi. Examples of bacteria include pathogenic Escherichia coli, Legionella, Campylobacter, etc. Examples of viruses include non-enveloped viruses such as adenovirus, RS virus, norovirus, and enveloped viruses such as coronavirus, influenza, herpes, etc. Examples of fungi include Candida, Trichophyton, etc.

[0013] The bio-nanocarbon, which is the anti-pathogenic agent of the present invention, exerts an anti-pathogenic effect not only through direct contact with pathogens but also indirectly or through a medium around them. Since the growth of microorganisms is inhibited even when the leachate is added to the medium, it is considered that some substance with an anti-pathogenic effect is released or the surrounding environment is changed. Since the medium exhibits an electromagnetic wave shielding effect, it is clear that the surrounding electrical environment is changed. Also, silver ions, which are typical antibacterial ions, do not show an antibacterial effect even when compounded in a polymer at about 2000 ppm. Also, a simple mixture of silica and carbon does not show water solubility or an antibacterial effect.

[0014] The following examples are shown to explain the present invention in more detail.

Examples

Example 1

[0015] The bio-nanocarbon of the present invention was produced according to the following procedure. 1.1 kg of wheat husks were placed in an electric furnace, and while gently flowing nitrogen containing 7% oxygen, they were kept at 2500-3000 ° C for 12 hours to carbonize, obtaining crude biocarbon. This was pulverized in a jet mill to obtain bionanocarbon, which is the antipathogen agent of the present invention, having an average particle size of 212 nm and containing 6% silicon oxide. FTIR is shown in Figure 1, particle size distribution diagram in Figure 2, and micrograph in Figure 3. From the photograph, a hierarchical structure was recognized, and it was presumed to be a mixture of graphite, graphene, and silicene. In particular, a sharp peak was present at 1600 cm-1 to 1100 cm-1 in FTIR, suggesting the presence of a silicene oxide structure. This means that when producing such biocarbon, water can be added to the carbonized and burned rice husks, filtered to remove insoluble matter, and the structure can be confirmed by FTIR or the like to produce it. Example 2

[0016] The anti-pathogenic effect of the anti-pathogenic agent of Example 1 was confirmed by the following method. The procedure for the four species, E. coli, S. aureus and Candida albicans, was as follows. 1. 0.1 ml of the bacterial solution was adjusted to 1 x 105 cells / mL in PBS solution (pH 7.0), inoculated onto Sabouraud dextrose medium, and cultured at 37°C for 24 hours. 0.1 ml of 2000 ppm biochar PBS solution (pH 7.0) was added to the plate. For the control, 0.1 ml of PBS was added to the plate. 2. After culturing for 48 hours, the absorbance of the plate at 680 nm was measured. 3. The removal rate was calculated using the following formula: Removal rate=100 * (Control absorbance-Sample absorbance) / Control absorbance The results are shown in Table 1. It can be seen that there is an excellent anti-pathogen effect.

[0017] [Table 1] Example 3

[0018] 0.2% of the bio-nanocarbon of Example 1 and 99.8% of polyethylene were heated, melted and mixed at 180 °C, and pellets were produced using a pelletizer. The anti-pathogen effect of this pellet was examined using yeast. The samples were adjusted as follows. Sample 1 3 ml of water was added to 0.1 g of the pellet and immersed for 24 hours, and the immersion liquid was obtained by decantation to obtain Sample 1. Sample 2 3 ml of water was added to the pellet of the residue of Sample 1 and immersed for 24 hours, and the supernatant was taken by decantation to obtain Sample 2. Sample 3 3 ml of water was added to the pellet of the residue of Sample 2 and immersed for 24 hours, and the supernatant was taken by decantation to obtain Sample 3. Sample 4 The pellet of the residue of Sample 3 was taken as Sample 4. Sample 5 The pellet of Example 1 Sample 6 Water was used as a control. 200 μl of a 0.1% yeast solution was seeded in a Sabouraud dextrose medium and pre-cultured for 24 hours. 200 μl of each sample was added thereto and cultured for 24 hours, and colony formation and the like were observed to examine the effect on yeast. Furthermore, a petri dish was placed between mobile phones emitting a spurious electromagnetic wave of 157 V / m, and the absorption of the spurious wave was examined. The results are shown in Table 2. From this, it can be seen that the leachate also has an anti-pathogen effect.

[0019] [Table 2]

[0020] <Comparative Example 1> The wheat husk was calcined while ventilating at 1000 °C to obtain biochar in the form of rice husk silica with a purity of 98%. This had no antibacterial effect on yeast and no water solubility.

[0021] <Comparative Example 2> The apple branches were processed in the same manner as in Example 1 to obtain biochar with a carbon content of 99%. This had no antibacterial effect on yeast and was also not water-soluble.

Industrial Applicability

[0022] The present invention can be applied to antibacterial coatings and sterilizing coatings.

Claims

1. The anti-pathogen agent is made of bionanocarbon (also known as biochar) obtained by carbonizing biomass, characterized in that the biomass is rice husk and the mass ratio of silicon oxide to carbon is 5:95 to 20:

80.

2. The anti-pathogen agent according to claim 1, which exerts an anti-pathogen effect via an aqueous medium when mixed and fixed in a polymer.

3. The anti-pathogenic agent according to claim 1 or 2, characterized in that the pathogen is a virus, a bacterium or a fungus.

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