JP6135486B2 - Resin molded body - Google Patents

Description

  The present invention relates to an antibacterial resin molded body.

  Conventionally, as a means for imparting antibacterial properties to a resin molded body, an antibacterial agent using an antibacterial metal ion such as silver, copper, or zinc is mixed with the resin and molded with the resin, or the surface of the resin molded body It is common to coat it.

  For example, Patent Document 1 describes a resin molded body formed of a resin mixed with a fatty acid silver salt. Further, in Patent Document 2, a composite powder in which an action site such as zinc oxide that inhibits the activity of a specific enzyme and an adsorption site made of silica or the like that adsorbs the specific enzyme are included in a resin or the like. Is described.

  However, for example, in the case of a resin molded product used in a place where it touches the human body such as the human body or the skin surface, the antibacterial component requires biocompatibility and safety such as non-toxicity. May cause metal allergy.

  In addition, Patent Document 3 discloses that a plant fiber, a thermoplastic fiber, and an antibacterial coffee extraction residue or tea extraction residue are mixed and heat-treated by a dry fiber method to form a sheet. It has been described. However, antibacterial properties due to coffee extraction residue or tea extraction residue are not sufficient.

JP 2005-48031 A JP 2004-204403 A Japanese Patent Application Laid-Open No. 2004-137631

  An object of the present invention is to provide an antibacterial resin molded article excellent in biocompatibility and safety.

The resin molding of the present invention is characterized in that it is molded from a PMMA resin containing antibacterial fibroin in which thiocyanate ions are bonded to fibroin as a filler.

  Silk is used as a surgical suture, and is a material known to be safe to put in the body by completely removing sericin. Since fibroin is obtained by removing sericin from silk, it can be said that the biocompatibility and safety are proven based on the results of the suture. Therefore, a resin containing fibroin as a filler is also excellent in biocompatibility and safety.

  In addition, the present inventors have found that fibroin containing a β sheet structure in which thiocyanate ions are hydrogen-bonded exhibits antibacterial properties. The β sheet structure (straight chain structure) includes a parallel β sheet and an antiparallel β sheet.

The mechanism of antibacterial activity in fibroin is not necessarily clear at the present time, but is considered as follows. That is, thiocyanate ions (SCN ⁻ ) are stably survived as HSCN by hydrogen bonding to fibroin. The HSCN is considered to have antibacterial properties. And it is thought that the antibacterial property by HSCN becomes easy to exhibit because the coupling | bonding destination is (beta) sheet structure (linear structure).

  Fibroin includes an α-helix structure (spiral structure) and a β-sheet structure, and preferably has a β-sheet structure more than the α-helix structure. This is because when the thiocyanate ion is hydrogen-bonded to the α-helix structure, antibacterial activity due to HSCN may be less likely to be exhibited compared to the case where the thiocyanate ion is hydrogen-bonded to the β-sheet structure.

  And the resin molded product molded with the resin containing the above antibacterial fibroin as a filler is also considered to exhibit antibacterial properties as a whole by the effect of the antibacterial fibroin exposed on the surface of the resin molded product. It is done. Here, “expression” may be a partial expression of antibacterial fibroin having a predetermined shape.

  ADVANTAGE OF THE INVENTION According to this invention, the antibacterial resin molding excellent in biocompatibility and safety | security can be provided.

  In order to increase the rate at which the antibacterial fibroin is exposed on the surface of the resin molded body, the content of the antibacterial fibroin is preferably 1% by mass or more, and more preferably 10% by mass or more.

  Moreover, it is preferable that the content rate of an antimicrobial fibroin is 40 mass% or less for the intensity | strength and workability of a resin molding.

  Although it does not specifically limit as a shape of an antimicrobial fibroin, A fibrous form, a granular form, etc. can be illustrated.

  When the antibacterial fibroin is fibrous or granular, the thickness of the resin molding is preferably 1 to 10 times, more preferably 1 to 3 times the fiber diameter or particle size of the antibacterial fibroin. If it is less than 1 time, molding becomes difficult, and if it exceeds 10 times, the rate at which the antibacterial fibroin is substantially exposed on the surface of the resin molded product becomes low.

Considering the heat resistant temperature of the anti-fungal fibroin, the molding temperature is preferably up to about 0.99 ° C..

Polymethyl methacrylate resin (PMMA) which is a thermosetting resin is used . PMMA currently used for dental materials, bone cement and the like is most preferable in terms of excellent biocompatibility and high hardness.

  Antibacterial regenerated silk can have antibacterial properties against gram-negative and gram-positive bacteria. Examples of gram-negative bacteria include Escherichia coli. Examples of gram positive bacteria include Staphylococcus aureus and mutans bacteria.

  Antibacterial regenerated silk can further have antibacterial properties against fungi (distinguished from bacteria, also referred to as fungi). Candida etc. can be illustrated as fungi.

  Although the application destination of the resin molded body is not particularly limited, medical equipment, medical materials, cosmetic materials and the like can be exemplified as suitable usage destinations.

  In particular, it is preferable that the proliferation value when mutans bacteria measured according to JIS Z2801 for the resin molded body is cultured for 24 hours is less than -3.0. A mutans bacterium is one of the causative bacteria of caries present in the oral cavity of humans, and the regenerated silk-containing PMMA resin molded article having a high antibacterial property (the growth value is less than −3.0) is used for dentures, etc. This is because it is suitable as a dental material.

  Moreover, it is preferable that the proliferation value when mutans bacteria measured according to JIS L1902 about antimicrobial fibroin is cultured for 18 hours is 0.4 or less, and more preferably 0 or less. This is because when the proliferation value is 0.4 or less, antibacterial properties can be exhibited when the resin molded body is formed.

  About the resin molding of the Example which actualized this invention, it demonstrates with a manufacturing method.

<Production method of regenerated silk (antibacterial fibroin)>
First, regenerated silk (antibacterial fibroin) was produced by the following method.

1. Desericin treatment / washing process 9.0 g of raw material obtained by chopping 20 rabbit cocoons is treated with 400 mL treated water in which urea, mercaptoethanol and tris (hydroxymethyl) aminomethane (Tris) are dissolved in water ( The urea concentration was 8M, the mercaptoethanol concentration was 2% by volume, and the Tris concentration was 50 mM. The mixture was stirred at 80 ° C. for 8 hours to dissolve sericin contained in the raw material koji in the treated water.
Thereafter, insoluble silk (fibroin) is filtered off from the treated water, and the fibroin obtained by filtration is washed with distilled water, and then left to stand in a thermostatic bath at 30 ° C. for about half a day and dried. 6.7 g of fibroin was obtained.

2. Thiocyanate aqueous solution treatment 130 g of lithium thiocyanate was dissolved in 100 mL of water to prepare an aqueous solution (pH 4.6).

  In this lithium thiocyanate aqueous solution, 6.7 g of the fibroin obtained above was immersed and dissolved to obtain about 200 mL of an aqueous fibroin solution.

3. Dialysis (treatment with lithium dethiocyanate)
About 20 mL of the about 200 mL of fibroin aqueous solution obtained above is put into 10 dialysis tubes made of regenerated cellulose, and then about 50 to 65 times (volume) of distilled water is added to the fibroin aqueous solution to be treated. Each dialysis tube was immersed in the resulting container for 4 to 6 days, and lithium thiocyanate was removed by dialysis. During the period when each dialysis tube was immersed in distilled water, the distilled water in each container was changed twice a day.

4). Freeze drying (drying process)
The fibroin aqueous solution from which lithium thiocyanate was removed, obtained as described above, was divided into four equal parts, each was allowed to stand in an ethanol bath at -50 ° C. for about 1 hour and pre-frozen, and then for 1-2 days. Freeze drying was performed to obtain 6.0 g of porous dry fibroin.

5. HFIP dissolution treatment 1 g of the dried fibroin obtained above was put in 10 mL of hexafluoroisopropanol (HFIP), that is, about 10% by mass of fibroin was added to HFIP, sealed, and stirred at 50 ° C. for 2 days. A fibroin HFIP solution was obtained.

6). Spinning (filament regenerated silk molding process)
The fibroin HFIP solution obtained above was put into a 2.5 mL syringe with a nozzle having an inner diameter of 0.25 mm and a length of 10 mm, and the fibroin HFIP solution was added to the nozzle with the tip of the nozzle in ethanol. A regenerated silk having a diameter of about 120 μm, which was formed by discharging fibroin into a thread, was discharged into ethanol from the opening at the tip.

7). Heat treatment (autoclave treatment)
The filamentous regenerated silk (antibacterial fibroin) obtained above was placed in an autoclave and subjected to high-temperature and high-pressure steam treatment under conditions of 121 ° C., 100 kPa, 15 minutes. After the treatment, the residual amount of HFIP remaining on the regenerated silk (antibacterial fibroin) was measured by combustion ion chromatography (AQF-100, GA-100, manufactured by Mitsubishi Chemical Corporation) and found to be 510 ppm.

<Antimicrobial test of regenerated silk (antimicrobial fibroin)>
The filamentous regenerated silk obtained by the above production method was tested for antibacterial properties using cotton as a standard fabric in accordance with JIS L1902: 2008 (antibacterial test method and antibacterial effect of textile products).

A. Test conditions Quantitative test: Bacterial solution absorption method Viable count method: Pour plate culture method Test strain: E. coli (NBRC3301, Gram-negative bacilli and facultative anaerobes)
: Staphylococcus aureus (NBRC12732, Gram-positive cocci and facultative anaerobe)
: Mutans bacteria (IFO13955, Gram-positive streptococci and facultative anaerobes)
: Candida (NBRC1594, colorless incomplete yeast belonging to fungi)
Number of specimens: each sample 3
Sample weight: 0.2g
Inoculum volume: 0.1 mL
Test bacteria suspension: 0.05% nonionic surfactant added

A. Test operation Put a sample (0.2 g) in a vial, inoculate the sample with a bacterial solution (0.1 mL), and then tighten the cap of the vial. Then, it culture | cultivated at 37 degreeC for 18 hours. Thereafter, the bacteria were washed out from the specimen, and the number of viable bacteria was measured.

C. Measurement item The average value of the common logarithm of the viable cell count (hereinafter referred to as “viable cell logarithm”) was determined for each sample.

D. Test results Table 1 shows the logarithm of viable bacteria of each sample. The proliferation value is a value of “logarithm of viable bacteria after culturing−logarith of viable bacteria immediately after inoculation”. In addition, as a comparative example, the following antibacterial tests were also performed on the following fibers, and the measurement results are listed in Table 1.
・ Cotton fiber (unprocessed product)
・ Cotton fiber (fiber before performing “1. Desericin treatment / washing process” above)
・ Desericin cocoon fiber (fiber obtained by performing only “1. Desericin treatment / washing process” above)
・ Polyester fiber (PET fiber)
・ Nylon fiber

  As shown in Table 1, for Escherichia coli, cotton, cocoon fiber, de-sericin cocoon fiber, PET fiber, and nylon fiber as comparative examples are all antibacterial, but regenerated silk (antibacterial fibroin) has antibacterial properties. there were.

  As for Staphylococcus aureus, cotton fiber, wrinkle fiber, de-sericin wrinkle fiber, PET fiber, and nylon fiber as comparative examples were all non-antibacterial, but regenerated silk (antibacterial fibroin) was antibacterial.

  As for the mutans bacteria, the cotton fiber and the de-sericin silk fiber as comparative examples have no antibacterial property, but the regenerated silk (antibacterial fibroin) has the antibacterial property.

  As for Candida, cotton fibers and de-sericin koji fibers as comparative examples had no antibacterial property, and regenerated silk (antibacterial fibroin) also did not have antibacterial properties until the number of bacteria was significantly reduced during culture. However, compared to cotton fiber and de-sericin silk fiber, there is almost no increase in the number of bacteria during regenerated silk (antibacterial fibroin) culture, and a certain degree of antibacterial activity can be expected (the antibacterial test results of resin moldings described below) reference).

<Production method of resin molding>
Next, the resin molding was shape | molded with the following method with PMMA resin which contains said reproduction | regeneration silk (antibacterial fibroin) as a filler.

1. The regenerated silk (antibacterial fibroin) was cut into a length of 2 to 3 mm.
2. To 1 g of the methacrylic acid ester polymer, 0.55 g (25% by mass of the molded product) of the above-mentioned 1 recycled silk was added and mixed well. In addition, about the antibacterial property test with respect to Candida mentioned later, what added 0.28g (15 mass% of a molded object) of said 1 reproduction | regeneration silk and what added 1.1g (40 mass% of a molded object) are also produced. did.
3. 0.6 g of methyl methacrylate was added dropwise to the above raw material 2 and mixed well.
4). The above 3 raw materials were allowed to stand at room temperature for 25 minutes.
5. The above 4 raw materials were sandwiched between upper and lower molds made of iron plate and hot press molded under the conditions of 20 MPa, 90 ° C. and 30 minutes so that the distance between the plates was 0.2 mm.
6). The 0.2 mm-thick resin molded body molded in 5 above was taken out from the upper and lower molds and washed in ion-exchanged water for 30 minutes.
7). The resin molded body of the above 6 was dried.

  Moreover, the film which consists of a polyethylene (PE) resin single-piece | unit was used as a comparative example.

  As another comparative example, a resin molded body was molded by the same method as described above using a PMMA resin containing natural silk as a filler. The blending amount of natural silk is 0.55 g (25% by mass of the molded product).

As yet another comparison, a resin molded body made of a single PMMA resin was molded by the following method.
1. To 1 g of the methacrylic acid ester polymer, 0.6 g of methyl methacrylate was dropped and mixed well.
2. The raw material 1 was allowed to stand at room temperature for 25 minutes.
3. The above two raw materials were sandwiched between upper and lower molds made of iron plate and hot press molded under the conditions of 20 MPa, 90 ° C. and 30 minutes so that the distance between the plates was 0.2 mm.
4). The resin molded body having a thickness of 0.2 mm molded in the above 3 was taken out from the upper and lower molds and washed in ion exchange water for 30 minutes.
5. The resin molded body of the above 4 was dried.

<Antimicrobial test of resin molding>
The resin molding obtained by the above production method was subjected to an antibacterial test in accordance with JIS Z2801: 2010 (antibacterial processed product-antibacterial test method / antibacterial effect).

A. Test conditions Test strain: E. coli (NBRC3972)
: Staphylococcus aureus (NBRC12732)
: Mutans bacteria (IFO13955)
: Candida (NBRC1594)
Number of specimens: each sample 3
Sample size: 5cm x 5cm
Inoculum volume: 0.4 mL
Test medium: SCDLP medium

A. Test operation About each of the unprocessed test piece and the test piece which performed antibacterial processing, the test microbe liquid was dripped, the film was covered, and it culture | cultivated at 35 degreeC in the petri dish for 24 hours. After culturing the test solution from the film and the test piece, the number of bacteria in the solution was measured by an agar plate culture method, and the number of viable bacteria per unit area of each test piece was measured.

C. Measurement item The logarithm of viable bacteria was determined from the above viable cell count. The case where the log of live bacteria after culture was less than the log of live bacteria immediately after inoculation was regarded as antibacterial, and the case where it was greater than the log of live bacteria immediately after inoculation was evaluated as having no antibacterial properties.

D. Test results Table 2 shows the logarithm of viable bacteria of each test piece.

  As shown in Table 2, for E. coli, the PE film and the natural silk-containing PMMA resin molded product had no antibacterial properties, and the PMMA resin molded product had antibacterial properties. The contained PMMA resin molded product had high antibacterial properties.

  As for Staphylococcus aureus, the PE film had no antibacterial property, the natural silk-containing PMMA resin molded product had some antibacterial properties, and the PMMA resin molded product and the regenerated silk-containing PMMA resin molded product had high antibacterial properties.

  Regarding mutans bacteria, the PE film had antibacterial properties and the PMMA resin molded product had high antibacterial properties, but the recycled silk-containing PMMA resin molded product had even higher antibacterial properties than this PMMA resin molded product. (Proliferation value is less than -3.0).

  Since mutans bacteria are one of the causative bacteria of caries present in the oral cavity of humans, it can be said that the regenerated silk-containing PMMA resin molded article having high antibacterial properties is suitable as a dental material such as dentures.

  Regarding Candida, the PE film and the PMMA resin molded product had no antibacterial property, and the recycled silk-containing PMMA resin molded product had a slight antibacterial property. And antibacterial property was high in the case of 25 mass% with respect to the case where the reproduction | regeneration silk content rate is 15 mass% or 40 mass%.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the meaning of invention, it can change suitably and can be actualized.

Claims (7)

A resin molded body molded of PMMA resin containing antibacterial fibroin in which thiocyanate ions are bound to fibroin as a filler.   The resin molding according to claim 1, wherein the content of the antibacterial fibroin is 1% by mass or more.   The resin molding according to claim 2, wherein the content of the antibacterial fibroin is 40% by mass or less.   The resin molded body according to any one of claims 1 to 3, wherein the antibacterial fibroin is fibrous and the thickness of the resin molded body is 1 to 10 times the fiber diameter of the antibacterial fibroin.   The resin molded body according to any one of claims 1 to 3, wherein the antibacterial fibroin is granular and the thickness of the resin molded body is 1 to 10 times the particle size of the antibacterial fibroin.   The resin molded article according to claim 1, wherein the proliferation value when mutans bacteria measured according to JIS Z2801 is cultured for 24 hours is less than -3.0.   The resin molding according to claim 1, wherein the antibacterial fibroin has a proliferation value of 0.4 or less when mutans bacteria measured according to JIS L1902 are cultured for 18 hours.