KR20240042378A - Composition for shielding radioactive ray and radiation shielding material comprising thereof - Google Patents

Abstract

The present invention provides a composition for radiation shielding, comprising Cladosporium sp. microorganisms with radiation-shielding inorganic particles attached to the surface.

Description

Composition for shielding radioactive ray and radiation shielding material comprising the same

The present invention relates to a composition for radiation shielding and a radiation shielding material containing the composition.

Radiation (radioactive ray) is generally an electromagnetic wave or particle ray generated when a radioactive material (radioactive isotope) decays into a stable material, such as gamma ray (γ-ray), These include beta rays (β-ray) and alpha rays (α-ray).

Radiation mainly occurs in places that handle radioactive materials, such as nuclear medicine-related hospitals, nuclear power plants, nuclear waste disposal facilities, military nuclear material facilities, and non-destructive industries. When exposed to such radiation in large amounts or for a long period of time, DNA is damaged and is fatal to the human body, so efficient radiation shielding is a very important factor for workers.

The handling of radioactive materials is increasing every year, and the current global radiation shielding market is known to be worth approximately 1,700 trillion won.

Lead has a high atomic number (82) and a high density, so it has excellent radiation shielding properties and has been used as a radiation shielding material for a long time. To this day, most radiation shielding materials contain a large amount of lead. However, lead-based radiation shielding materials are not only heavy, but lead can cause neurological and cardiovascular diseases in the human body, and cause environmental problems such as soil pollution.

Research has been conducted on eco-friendly radiation shielding materials to replace lead, and metal materials with high densities such as barium, bismuth, tungsten, zirconium, tin, cerium, and antimony are known to have a radiation shielding effect. For stability reasons, these metal substances are mainly used as shielding agents in the form of metal salts and metal oxides rather than pure metal forms.

For example, barium sulfate (BaSO ₄ ) is a substance widely distributed in nature, is insoluble in water, is harmless to the human body, and has an excellent radiation shielding effect, so it is used as a radiological contrast agent.

Radiation shielding suits, aprons, etc. need to be light and flexible for mobility. Therefore, radiation-shielding metal compounds are made into nano- or micro-particle sizes, mixed with polymer materials or binders, and hardened to produce shielding sheets, or are used as shielding coating materials.

Republic of Korea Patent No. 10-1145703 discloses a radiation shielding sheet manufactured by mixing and curing barium sulfate powder with a silicone polymer and a silicone curing accelerator.

Republic of Korea Patent No. 10-2035512 discloses a coating agent for radiation shielding that mixes radiation shielding agents such as tungsten, bismuth, barium, europium, dysprosium, and strontium with a binder resin such as epoxy and urethane.

Republic of Korea Patent No. 10-1731785 is a flexible hydrogel matrix in which radiation-shielding metal particles are cross-linked with first polymers such as alginate, chitosan, and hyaluronic acid and second polymers such as polyacrylamide, polyvinyl alcohol, and polyethylene. A radiation shielding material imparted with elasticity is disclosed.

Although these radiation-shielding particles have a lower density than lead (11 g/cm ³ ), they generally have a high density of 4.5 g/cm ³ or more, and have poor miscibility and dispersibility with respect to the polymer materials they are mixed with, so the content of the shielding particles is limited. There are limitations, and the higher the content of radioactive shielding particles, the heavier the shielding material becomes. In addition, since the radiation shielding effect of these shielding materials depends on the content of radiation shielding particles rather than the polymer material, flexibility may be reduced by increasing the thickness of the shielding material to increase shielding power.

Republic of Korea Patent No. 10-1145703 Republic of Korea Patent No. 10-2035512 Republic of Korea Patent No. 10-1731785

The purpose of the present invention is to provide a new radiation-shielding composition and radiation-shielding material that has excellent radiation-shielding ability and is flexible and lightweight.

The present invention provides a composition for radiation shielding, comprising Cladosporium sp. microorganisms with radiation-shielding inorganic particles attached to the surface.

In one embodiment, the radiation-shielding inorganic particle may be an inorganic particle selected from the group consisting of barium, bismuth, tungsten, zirconium, tin, cerium, antimony, or a metal salt or metal oxide thereof. In one embodiment, the radiation-shielding inorganic particle may be an inorganic particle selected from the group consisting of barium sulfate, barium carbonate, bismuth oxide, and tungsten oxide, but is preferably barium sulfate.

In one aspect, the Cladosporium genus microorganism may be Cladosporium cladosporioides , and in one example, the Cladosporium genus microorganism may be Cladosporium cladosporioides. It may be the Ceb-RadF-001 strain (accession number: KCCM12440P).

In one aspect, the radiation shielding composition may further include microorganisms of the genus Phanerochyta and/or microorganisms of the genus Trichosporon .

In one aspect, the microorganism of the Phanerochaete genus may be Phanerochaete chrysosporium or Phanerochaete sordida , and in one example, Phanerochaete chrysosporium Y-2 strain (accession number: KCCM10725P) can be used.

In one aspect, the microorganism of the Trichosporon genus may be Trichosporon loubieri , and in one example , the Trichosporon loubieri Y1 -A strain (accession number: KCTC10876BP) may be used. there is.

Meanwhile, the present invention provides a radiation shielding material containing the radiation shielding composition.

In one aspect, the radiation shielding material may include a microbial immobilization carrier.

The microorganism immobilization carrier may be a porous material, but is not limited thereto.

The microorganism immobilization carrier may be selected from polymer resin, activated carbon, zeolite, non-woven fabric, or fabric, but is not limited thereto.

The microorganism immobilization carrier may further include carbon nanotubes or graphene.

The radiation shielding material according to the present invention uses Cladosporium sp . microorganisms that can effectively attach radiation-shielding inorganic particles to the surface, thereby producing radiation-shielding inorganic particles without the dispersion technology and polymer binder required in the prior art. It can be effectively dispersed in the shielding material.

In addition, the radiation shielding material according to the present invention is harmless to the human body and does not cause environmental pollution problems even when disposed of. It is significantly lighter and more flexible than conventional shielding materials, allowing for comfortable worker activity, and can be used as materials for radiation shielding clothing, aprons, gloves, shoes, etc. Alternatively, it has high utility value as a construction material.

Figure 1 shows the arrangement of microbial samples according to the irradiation distance in the radiation (gamma ray) irradiation room implemented in the present invention.
Figure 2 shows the change in shape of each microbial strain according to an increase in radiation (gamma ray) irradiation in an experimental example of the present invention.
In Figure 3, (b) is a photograph of the growth of the Cladosporium cladosporioides strain that was not irradiated with radiation, and (c) is a photograph of the growth of the Cladosporium cladosporioides strain with an absorbed dose of 392 Gy.
Figure 4 shows a porous polyurethane filter used for microbial attachment in the present invention.
Figure 5 shows the arrangement of shielding material samples according to the irradiation distance in the radiation (gamma ray) irradiation room implemented in the present invention.
In Figure 6, a) is a micrograph of a Cladosporium cladosporioides strain cultured without the addition of barium sulfate as in Example 3, and b) is a photomicrograph of Cladosporium cladosporioides strain cultured with the addition of barium sulfate as in Example 5. This is a photomicrograph of a Sporium cladosporioides strain.

In the present invention, 'radiation' includes ionizing radiation, gamma rays, X-rays, neutron rays, alpha rays, and beta rays.

In the present invention, 'microorganism' is or includes 'strain' unless otherwise specified.

In the present invention, 'single microorganism' refers to a microorganism consisting of only one type of strain.

In the present invention, 'complex microorganism' refers to a group of microorganisms consisting of two or more strains. Complex microorganisms include mixing cultures of single microorganisms or culturing two or more strains in the same medium.

In the present invention, in relation to radiation dose, 'low dose', 'medium dose', and 'high dose' are used in relation to the radiation dose in the embodiments of the present invention. It is only a term used to compare the radiation shielding effects of different radiation shielding effects, and does not imply an absolute range of hazards. The dose unit 'Gy' (Gray) is a unit that represents the radiation energy absorbed by a material. When 1 joule (J) is absorbed per 1 kg of material, it is defined as 1Gy. For example, if exposed to more than 1 Gy of radiation at a time, acute radiation sickness occurs in almost all people, and if the whole-body radiation dose is extremely high (usually more than 20 Gy), serious acute neurovascular disease can occur. there is. For reference, the highest radiation exposure to power plant workers in the Chernobyl accident was 16 Gy. In the embodiments of the present invention, 220.6 Gy and 392 Gy are expressed as low doses, but this only means that they are relatively low compared to 21,687 Gr and 38,600 Gy, and are tens to hundreds of times the lethal dose.

The present inventor studied various microorganisms to select microorganisms that can effectively block high-risk radiation such as gamma rays and , 2020.10.14. It was confirmed that single microorganisms of Trichosporon sp. and their complex microorganisms have excellent radiation shielding ability . Filed under Korean Patent Application No. 10-2020-0132329.

Furthermore, the present inventors added barium sulfate, a radiation-shielding inorganic particle, to Cladosporium sp., which has the best radiation-shielding ability among the microorganisms, and cultured them. As a result, surprisingly, barium sulfate was added to the Cladosporium sp. The present invention was completed by confirming that Cladosporium sp. naturally attached to the surface of microorganisms and aggregated with each other.

The present invention provides a composition for radiation shielding, comprising Cladosporium sp. microorganisms with radiation-shielding inorganic particles attached to the surface.

Since the radiation-shielding inorganic particles are dispersed in the culture medium, they are preferably water-insoluble.

The radiation-shielding inorganic particles can be any known inorganic particles having radiation-shielding properties. In one embodiment, the radiation-shielding inorganic particle may be barium, bismuth, tungsten, zirconium, tin, cerium, antimony, or a metal salt or metal oxide thereof. In one aspect, the radiation-shielding inorganic particle may be barium sulfate, barium carbonate, bismuth oxide, or tungsten oxide, but is preferably barium sulfate.

Barium sulfate is a material used in contrast media and is widely known as a radiation shielding agent. Barium carbonate (BaCO ₃ ) is soluble in acidic conditions such as stomach acid, but is water-insoluble and is known to have excellent shielding ability against gamma rays and X-rays (Journal of Radiation Protection and Research 2017; 42(1): 26-32). Bismuth oxide (Bi ₂ O ₃ ) is known to have an excellent radiation shielding effect (Fibers and Polymers volume 17, pages2047-2054 (2016)). In one aspect, the radiation-shielding inorganic particles may be nano-sized or micro-sized.

The Cladosporium sp . microorganism is known as a black mold that produces melanin pigment, and Cladosporium cladosporioides is preferred, but is not limited thereto. In one example, it may be the Cladosporium Cladosporioides Ceb-RadF-001 strain. The Cladosporium Cladosporioides Ceb-RadF-001 strain was released on February 26, 2019. It is deposited at the Korean Culture Center of Microorganisms (Address: 45 Hongjenae 2-ga-gil, Seodaemun-gu, Seoul) with deposit number KCCM12440P.

The radiation shielding composition may be the strain itself, or its culture or mixture, and the strain, culture, or mixture may be in the form of semi-dried or dried powder, if necessary.

In one aspect, the radiation shielding composition can be prepared by culturing a Cladosporium sp . strain and then adding radiation-shielding inorganic particles and further cultivating it. Alternatively, it can be prepared by drying and powdering the strain and mixing it with barium sulfate.

In another aspect, the radiation shielding composition may be prepared by culturing a Cladosporium sp. strain in a culture medium to which a radiation-shielding inorganic matrix is further added.

The radiation shielding composition of the present invention may further include microorganisms of the genus Phanerochaete and/or Trichosporon sp. in addition to microorganisms of the genus Cladosporium sp.

The microorganism of the Phanerochaete sp . is known as a white mold, and Phanerochaete chrysosporium or Phanerochaete sordida are preferred, but are not limited thereto. In one example, the strain Phenerochyte Chrysosporium Y-2 may be used. The Phenerochyte Chrysosporium Y-2 strain was developed on December 19, 2005. It is deposited at the Korean Culture Center of Microorganisms (KCCM), address: 45 Hongjenae 2-ga-gil, Seodaemun-gu, Seoul, with deposit number KCCM10725P.

The microorganism of the Trichosporon sp . is a yeast, and Trichosporon loubieri can be preferably used, but is not limited thereto. In one example, the strain Trichosporon rubieri Y1-A can be used. The Trichosporon rubieri Y1-A strain was developed on February 26, 2001. It has been deposited at the Korea Research Institute of Bioscience and Biotechnology Biological Resources Center (KCTC, Korean Collection for Type Cultures, address: 181 Ipsin-gil, Jeongeup-si, Jeollabuk-do) under the deposit number KCTC10876BP.

The microorganisms according to the present invention can be cultured in a medium. Natural media or synthetic media can be used as the culture medium. The culture medium may include a carbon source, a nitrogen source, and inorganic salts.

The carbon source of the culture medium is not limited, but includes, for example, glucose, sucrose, fructose, maltose, lactose, dextrin, dextrose, starch ( Carbon sources may be known in the field of microbial culture, such as sugars such as starch, organic acids such as malic acid and citric acid, and fatty acids with low molecular weight.

The nitrogen source of the culture medium is not limited, but includes, for example, peptone, meat extract, yeast extract, dried yeast, casein, whey protein, soybean, ammonium salt, nitrate and other organic or inorganic nitrogen and sulfur. It may be a nitrogen source known in the field of microbial culture, such as a containing compound.

The inorganic salts of the culture medium are not limited, but include, for example, magnesium (Mg). Manganese (Mn), Calcium (Ca). Iron (Fe), potassium (K), sodium (Na), phosphorus (P), sulfur (S), boron (B), molybdenum (Mo), copper (Cu), cobalt (Co), zinc (Zn), etc. Likewise, it may be an inorganic salt known in the field of microbial culture.

The culture medium may further contain growth factors, if necessary, in addition to carbon source, nitrogen source, and inorganic salts. Growth factors may be amino acids, vitamins, nucleic acids, or compounds related thereto.

Microorganisms according to the present invention are not limited, but can be cultured in a temperature range of 20°C to 40°C, preferably in a culture temperature range of 25°C to 35°C.

Microorganisms according to the present invention are not limited, but can be cultured for 12 hours to 7 days, preferably 12 hours to 5 days.

The composition for radiation shielding of the present invention may contain single microorganisms or complex microorganisms. The complex microorganism of the present invention can be manufactured by mixing cultures obtained by cultivating each strain individually, or by culturing two or more strains together.

The concentration of microorganisms in the radiation shielding composition of the present invention is not limited, but is 0.5×10 ² CFU/ml or more, preferably 0.5×10 ³ CFU/ml or more, more preferably 0.5×10 ⁴ CFU/ml or more. , more preferably 0.5×10 ⁵ CFU/ml or more.

In one aspect, the composition for radiation shielding of the present invention may be a microbial culture medium, or a microorganism concentrated or purified from a culture medium, and may be in a dried or semi-dried form, if necessary.

An acceptable carrier may be added to the radioactive shielding composition of the present invention, if necessary. Acceptable carriers include those suitable as nutrients for selected microorganisms, such as saline solution, sterilized water, buffered saline solution, dextrose solution, maltodextrin solution, glycerol, and one or more of these ingredients can be mixed and used as necessary. Other common additives such as antioxidants, buffers, and bacteriostatic agents can be added. Additionally, diluents, dispersants, surfactants, binders, and lubricants can be additionally added to formulate a liquid formulation such as an aqueous solution, suspension, or emulsion, or a solid formulation such as powder.

Meanwhile, the present invention provides a radiation shielding material containing the radiation shielding composition. The radiation shielding material of the present invention may include microorganism immobilized media. A microorganism immobilization carrier can be used to allow microorganisms to adhere well while maintaining the shape of the shielding material. In one aspect, the microorganism immobilization carrier may be a porous material such as a matrix-type polymer resin with pores, activated carbon, zeolite, non-woven fabric, fabric, etc. The polymer resin is not limited, but may be, for example, synthetic polymers such as polyurethane, polyacrylamide, polyethylene glycol, and polyvinyl alcohol, or natural polymers such as agar, agarose, k-carrageenan, alginate, and chitosan. The form of the microorganism immobilization carrier is not limited, but may be foam, sponge, filter, sheet, or film, and, if necessary, may be in the form of powder or pellets. In one aspect, the radiation shielding composition may be supported on a microorganism immobilization carrier to stabilize the attachment, and additional culturing may be performed if necessary. Additionally, it can be semi-dried or dried as needed.

In one aspect, the radiation shielding material according to the present invention can be manufactured by impregnating the radiation shielding composition (microorganism culture or concentrate) with a microbial immobilization carrier. The impregnation time is to ensure that the microorganisms sufficiently adhere to the carrier, and can be appropriately adjusted depending on the type of microorganism and carrier. The impregnation time may be 12 hours or more, but is not limited thereto. The impregnation time may preferably be from 1 to 15 days. If necessary, a semi-drying or drying process may be added after impregnation. Natural drying is preferred.

In one embodiment, the microorganism immobilization carrier may be manufactured by a known entrapment or encapsulation method.

The microorganism immobilization carrier may further include carbon nanotubes or graphene, which are known to have a radiation shielding effect.

The radiation shielding composition or radiation shielding material according to the present invention can be used in various materials such as radiation shielding clothing (shielding clothing), shielding apron, shielding gloves, shielding hat, shielding shoes, shielding sheet, and shielding panel. At this time, the radiation shielding composition or radiation shielding material can be used as an internal material of a shielding product.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are for illustrative purposes only and the scope of the present invention is not limited to these examples.

Example 1: Solitary microorganism ( Phanerochaete chrysosporium Manufacture of composition for radiation shielding containing strain)

Phanerochaete chrysosporium Y-2 strain (accession number: KCCM10725P) was cultured in PDB medium with 200 g of potato infusion and 20 g of dextrose added to 1 liter of purified water in a shaking incubator at 130 rpm and 25°C for 5 days. did. Cultivation was stopped when the microbial growth curve was in the middle of the logarithmic and stationary phases and used in subsequent experiments.

Example 2: Solitary microorganism ( Trichosporon louberi Manufacture of composition for radiation shielding containing strain)

Trichosporon loubieri Y1 -A (accession number: KCTC10876BP) was grown in YPD medium containing 10 g of yeast extract, 20 g of peptone, and 20 g of dextrose in 1 liter of purified water, using a shaking incubator at 130 rpm and 25°C for 24 hours. Cultured. Cultivation was stopped when the microbial growth curve was in the middle of the logarithmic and stationary phases and used in subsequent experiments.

Example 3: Solitary microorganism ( Cladosporium cladosporioides Manufacture of composition for radiation shielding containing strain)

Cladosporium Cladosporioides Ceb-RadF-001 strain (accession number: KCCM12440P) was cultured in PDB medium to which 200 g of potato infusion and 20 g of dextrose were added to 1 liter of purified water in a shaking incubator at 130 rpm and 25°C for 7 days. did. Cultivation was stopped when the microbial growth curve was in the middle of the logarithmic and stationary phases and used in subsequent experiments.

Experimental Example 1: Measurement of survival rate of microbial strains following radiation irradiation

(1) Preparation of samples

Microorganism samples were prepared by placing 200 mL of each microorganism-containing composition prepared in Examples 1 to 3 in a 0.5 L Erlenmeyer flask with a baffle and closing it with a stopper made of hydrophobic silicone that is breathable and has low moisture evaporation. . Three microbial samples (3 repetitions) were prepared for each type of microorganism.

(2) Irradiation

Radiation experiments were conducted on the samples prepared above in the radiation irradiation laboratory of the Jeongeup branch of the Korea Atomic Energy Research Institute.

As shown in Figure 1, the microbial samples were placed at a distance of 25 cm and 379 cm from the radiation source in a cobalt 60 ( ⁶⁰ Co) irradiation chamber, respectively, and placed on a magnetic stirrer (DAIHAN Scentific model SHO-2D). It was raised and irradiated with radiation while continuing to stir at a speed of about 100 RPM. The control group did not receive radiation.

The laboratory temperature during the experiment period was maintained in the range of 21°C to 25°C without artificial control. The fluorescent lights in the laboratory were mainly turned on during work hours and turned off after work hours.

The absorbed dose rate of the sample was calculated from the ⁶⁰ Co source and irradiation distance, and radiation was irradiated for 93.08 hr over about 5 days.

^{The 60} Co radiation dose conditions are shown in Table 1 below.

Absorbed dose rate and total absorbed dose Absorbed dose rate irradiation distance investigation time Absorbed dose (D) 233 Gy/hr 25cm 93.08hrs 233 Gy/hr ×93.08 hr = 21,687 Gy 2.37 Gy/hr 379cm 93.08hrs 2.37 Gy/hr×93.08 hr = 220.6 Gy

(3) Measurement of survival rate of microorganisms after irradiation. For the Trichosporon loubieri strain, the number of viable microorganisms (bacterial concentration) was measured before irradiation (day 0) and after irradiation for about 5 days, and for the Cladosporium cladosporioides strain and the Phanerochaete chrysosporium strain. The amount of microbial biomass was measured before irradiation (day 0) and after irradiation for about 5 days, and is shown in Tables 2 to 4 below.

The survival rate of microorganisms was calculated as a percentage by calculating the number of viable cells (bacterial concentration) or biomass of the strain according to the radiation dose compared to the control, using a strain cultured for about 5 days without radiation (0 Gy) as a control. .

⁶⁰ Co according to radiation dose Cladosporium cladosporioides Strain survival rate goodness Dry biomass (mg/100mL) Survival rate compared to Control on day 5 (%) 0 days 5 days 0 Gy
(Control) 205 495 100% 220.6 Gy 205 531 107.3% 21687 Gy 205 289 58.4%

⁶⁰ Co according to radiation dose Phanerochaete chrysosporium Strain survival rate goodness Dry biomass (mg/100mL) Survival rate compared to Control on day 5 (%) 0 days 5 days 0 Gy
(Control) 288 623 100% 220.6 Gy 288 588 94.4% 21687 Gy 288 290 46.5%

⁶⁰ Co according to radiation dose Trichosporon louberi Strain survival rate goodness Viable bacteria count (CFU/mL) Survival rate compared to Control on day 5 (%) 0 days 5 days 0 Gy
(Control) 1.0×10 ⁶ 7.1×10 ⁶ 100% 220.6 Gy 1.0×10 ⁶ 6.9×10 ⁶ 97.2% 21687 Gy 1.0×10 ⁶ 5.6×10 ⁴ 0.8%

As shown in Tables 2 to 4, the Phanerochaete chrysosporium strain and the Trichosporon loubieri strain showed a high survival rate of over 94% at 220.6 Gy, and the Cladosporium cladosporioides strain showed 7.3% more growth compared to the control. It is believed that the Cladosporium cladosporioides strain showed higher growth by using the high energy of radiation as a growth energy source. Phanerochaete chrysosporium and Cladosporium cladosporioides strains survived by 46.5% and 58.4%, respectively, even after absorbing high doses (21,687 Gy). For reference, it can be seen that the microorganisms of the present invention have a significantly higher survival rate against radiation compared to the Deinococcus radiodurans strain, which American researchers reported to be very resistant to radiation, showing a 1% survival rate at 9,000 Gy.

Experimental Example 2: Experiment on morphological changes in microorganisms according to radiation dose

The same procedure as in Experimental Example 1 was performed, but the doses were increased to 392 Gy, 3,810 Gy, and 38,600 Gy for 7 days, respectively. In order to check the morphological changes in microbial strains according to the irradiation dose, 10 ml of each sample was diluted 10 ⁴ times with sterile saline solution and placed on a solid medium (NA, TSA, PDA) containing nutrients for each strain, and the samples survived. The growing microbial strains were observed and shown in Figure 2.

As shown in Figure 2, it can be seen that as the dose increases, the thickness and size of the mycelium and spores increase, and the endoplasmic reticulum and nuclear (DNA) material in the mycelium and spores increase.

Experimental Example 3: Depending on the radiation dose Cladosporium cladosporioides Measurement of strain growth

The Cladosporium cladosporioides strain, whose growth amount increased even at 220.6 Gy conducted in Experimental Example 1, was cultured in a culture dish as shown in FIG. 3, and then irradiated with gamma rays at 392 Gy, 3810 Gy, and 38600 Gy for 7 days, respectively, to determine the bacterial growth cycle. The size was measured again and the results are shown in Table 5 and Figure 3 below. Control is a strain that was not irradiated.

7 days ⁶⁰ Bacterial growth measurement results after Co irradiation Number of radiation days 0 days 7 days Control Diameter 3.60 cm Diameter 3.90 cm 392 Gy irradiation Diameter 3.59 cm Diameter 5.20 cm
(Growth increased by 1.78 times compared to the control group) 3,810 Gy irradiation Diameter 3.61 cm Diameter 3.10cm 38,600 Gy irradiation Diameter 3.62 cm Diameter 3.05cm

As shown in Figure 3 and Table 5, the Cladosporium cladosporioides strain has a growth ring diameter of 5.20 cm at a dose of 392 Gy, which is a 1.78-fold increase in size compared to the control. In addition, it can be seen that it does not die even at a high dose of 38,600 Gy.

Example 4: Preparation of microorganism-introduced radiation shielding material

As shown in FIG. 4, the microorganism-containing radiation shielding compositions prepared in Examples 1 to 3 were each supported on a porous polyurethane filter with a pore size of 25 ppi and a thickness of 10 mm, and then dried to form a radiation shielding material to which each microorganism was attached. After preparing the sample, a radiation shielding effect experiment was conducted.

The prepared radiation shielding material sample was placed in a ⁶⁰ Co irradiation room as shown in FIG. 5 and irradiated with radiation under the shielding ability test irradiation conditions shown in Table 6 below, and the results of the shielding rate measurement are shown in Table 7. At this time, the radiation shielding rate measurement sensor was attached to the back of the polyurethane shielding material sample using Alanine Pellet Dosimeters (Bruker BioSpin, USA), and the measuring device was an e-scan (Bruker BioSpin, USA). The control is a porous polyurethane filter that does not contain microorganisms.

Radiation shielding ability test irradiation conditions irradiation ⁶⁰ Co Temperature: 22.7±1℃ (irradiation room) Absorbed dose rate (Gy/hr) 2.3 Light illuminance: 30-70 Lx Total investigation time 48hrs Total absorbed dose: 110.4 Gy

Radiation shielding rate measurement results Treatment (3 repetitions) Radiation Shielding Rate
Shielding rate (%) = [(D ₀ -D)/D ₀ )]×100 Example strain 22hrs 48hrs Shielding ratio average (%) Control - 1 repetition
2 repetitions
3 repetitions 7.714206
5.359606
7.847337 10.222980
7.970050
9.021764

medium 6.973717 9.071598 8.2 Example 1 P. chrysosporium 1 repetition
2 repetitions
3 repetitions 15.006447
14.716102
14.467462 14.156591
14.255646
14.714976

medium 14.730004 14.375738 14.6 Example 2 T. loubieri 1 repetition
2 repetitions
3 repetitions 15.251054
12.580364
12.132538 15.172152
10.388004
13.717625

medium 13.321318 13.092594 13.2 Example 3 C. cladosporioides 1 repetition
2 repetitions
3 repetitions 28.317547
21.776832
22.431189 25.219327
22.316921
19.726522

medium 24.175189 22.420923 23.3 2mm thick lead
4mm thick lead
6mm thick lead 13.668271
17.361586
29.168030 11.646847
19.719506
26.541714 12.7
18.5
27.9

(D ₀ : Absorbed dose of directly exposed Alanine Pellet, D: Absorbed dose of Alanine Pellet on the back of the shielded sample) As shown in Table 7 above, treatment tool to which single microorganisms according to the present invention were attached (Examples 1 to 3) showed a higher radiation shielding rate than the control and 2 mm thick lead, and in particular, the treatment group to which Cladosporium cladosporioides strain was attached showed the highest radiation shielding rate of 23.3%, which showed a higher shielding rate than 4 mm thick lead.

In addition, the treatment group to which complex microorganisms according to the present invention were attached showed a significantly higher radiation shielding rate than that of single microorganisms, and the compositions of Examples 5 to 7 showed a radiation shielding rate comparable to that of lead with a thickness of 6 mm.

Example 5: Microorganisms introduced with radiation-shielding inorganic particles Preparation of strains

In the above examples, the correlation between radiation-shielding inorganic particles was confirmed for the Cladosporium cladosporioides strain with the best radiation-shielding ability.

1% of barium sulfate (BaSO ₄ ) powder was added to the culture medium of the Cladosporium cladosporioides strain cultured as in Example 3, and the culture was shaken for about 7 days.

In order to confirm the morphological changes in the cultured Cladosporium cladosporioides strain, 10 ml of each sample was diluted 10 ⁴ times with sterile saline solution and the microorganisms were observed under a microscope, as shown in FIG. 6.

In Figure 6, a) is a micrograph of Cladosporium Cladosporioides strain cultured without the addition of barium sulfate as in Example 3, and b) is a photomicrograph of Cladosporium cladosporium sulfate strain cultured with the addition of barium sulfate as in Example 5. This is a photomicrograph of a Sporium cladosporioides strain (×400).

As shown in b) of Figure 6, it can be seen that barium sulfate particles are aggregated and attached to the surface of the Cladosporium Cladosporioides strain.

Example 6: Preparation of radiation shielding material containing microorganisms introduced with radiation-shielding inorganic particles

The cells of the Cladosporium cladosporioides strain attached to barium sulfate prepared in Example 5 were recovered, pressed flat, moisture removed, and dried to prepare a shielding material sample. The thickness of the microbial layer of the flatly pressed dry sample was 0.5 mm. X-ray shielding tests on the above samples were conducted three times in the radiation laboratory of Gachon University College of Health Sciences, and the results are shown in Table 8 below. X-ray irradiation was conducted for 10.0 mSec (3.2 mAs) based on a tube voltage of 110 kV and a tube current of 320 mAs. The HEPA filter was used as a protective layer on the outer surface of the flatly pressed sample microorganisms. The experimental conditions were HEPA filter alone, HEPA filter with 2 mm thick lead, barium sulfate only, and shielding material introduced with Cladosporium cladosporioides strain, respectively, to compare the shielding effectiveness using each as a control.

1 repetition 2 repetitions 3 repetitions medium radiation shielding rate ^*
(%) No shielding 1.1 1.2 1.0 1.10 0 HEPA filter 0.9 1.1 0.9 0.97 11.8 HEPA filter+Pb(2mm) 0.2 0.3 0.2 0.23 79.1 HEPA filter+BaSO ₄ 0.8 0.7 0.7 0.73 33.6 HEPA filter+
C. cladosporioides
(Example 3) 0.8 0.7 0.8 0.77 30.0 HEPA filter+
BaSO ₄ +
C. cladosporioides
(Example 5) 0.5 0.7 0.6 0.60 45.5

(Radiation shielding rate ^* (%) = (No shielding measurement value - sample measurement value) / No shielding measurement valueAs shown in Table 8 above, radiation shielding of the Cladosporium Cladosporioides strain to which barium sulfate is attached. The rate was 45.5%, indicating that the shielding properties were significantly improved compared to barium sulfate alone (33.6%) and Cladosporium cladosporioides alone (30.0%).

Example 7: Radiation shielding material containing microorganisms introduced with radiation-shielding inorganic particles

As in Example 5 , the Cladosporium Cladosporioides strain culture medium to which barium sulfate particles were attached was placed on a porous polyurethane filter in the same manner as in Example 4 and dried to prepare a radiation shielding material sample, and the same A radiation shielding effect experiment was conducted using this method, and the results are shown in Table 9 below.

Radiation shielding rate measurement results Treatment (3 repetitions) Radiation Shielding Rate
Shielding rate (%) = [(D ₀ -D)/D ₀ )]×100 Example strain 22hrs 48hrs Shielding ratio average (%) Example 3 C. cladosporioides 1 repetition
2 repetitions
3 repetitions 23.986524
22.066954
24.536575 22.599665
20.268566
20.965874

medium 23.530018 21.278035 22.4 Example 5 C. cladosporioides
+ BaSO ₄ 1 repetition
2 repetitions
3 repetitions 28.924562
27.669525
29.256635 25.989622
25.942657
28.166556

medium 28.616907 26.699612 27.7

As shown in Table 9, the radiation shielding rate of the Cladosporium cladosporioides strain to which the barium sulfate particles of Example 5 were attached was found to be 27.7%, which was similar to that of the Cladosporium clades of Example 3. The radiation shielding rate of the Dosporioides strain was significantly higher than that of 22.4%.

Korea Microbial Conservation Center (overseas) KCCM12440P 20190226 Korea Microbial Conservation Center (overseas) KCCM10725P 20051219 Korea Research Institute of Bioscience and Biotechnology KCTC10876BP 20010226

Claims (10)

A composition for radiation shielding, comprising Cladosporium sp. microorganisms with radiation-shielding inorganic particles attached to the surface. According to paragraph 1,
A composition for radiation shielding, wherein the radiation-shielding inorganic particles are selected from the group consisting of barium, bismuth, tungsten, zirconium, tin, cerium, antimony, or metal salts or metal oxides thereof. According to paragraph 1,
The radiation-shielding inorganic particle is an inorganic particle selected from the group consisting of barium sulfate, barium carbonate, bismuth oxide, or tungsten oxide. According to paragraph 1,
A composition for radiation shielding, wherein the microorganism of the Cladosporium genus is Cladosporium cladosporioides . According to paragraph 1,
A composition for radiation shielding, wherein the microorganism of the Cladosporium genus is Cladosporium Cladosporioides Ceb-RadF-001 strain (accession number: KCCM12440P). A radiation shielding material comprising the radiation shielding composition according to claim 1. According to clause 6,
The radiation shielding material includes a microbial immobilization carrier. In clause 7,
A radiation shielding material, wherein the microorganism immobilization carrier is a porous material. According to clause 8,
A radiation shielding material wherein the microorganism immobilization carrier is selected from polymer resin, activated carbon, zeolite, non-woven fabric, or fabric. According to clause 6,
The radiation shielding material further includes carbon nanotubes or graphene.