JP3005667B2 - Modified silk protein, method for producing the same, and osteosynthetic material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a modified silk protein,
The present invention relates to a method for producing the same and an osteointegrative material .

[0002]

2. Description of the Related Art Bone substitute materials are widely used in the fields of orthopedics and dentistry as artificial joints, artificial bones, artificial ligaments, artificial tendons, artificial dental roots and the like. The main components used as bone substitute materials are metals, glass and ceramics.

[0003]

However, the above-mentioned metal and glass / ceramic bone substitute materials have a low affinity for living bone and have a drawback such that loosening and bone resorption become remarkable when used for a long period of time. Is a big problem.

[0004] In an attempt to solve this problem, research and development are being conducted to improve the function of the bone cement by using a methyl methacrylate polymer or by appropriately defining the composition of various alloys and ceramics. .

[0005] Therefore, attention has been paid to the fact that the component of living bone is hydroxyapatite, and techniques for improving the bone affinity of various materials have been developed. For example, a technique of plasma-coating hydroxyapatite on a metal surface such as titanium (J. Biomed. Mater. Res.
Journal, Vol. 27, pp. 603-610, 1993) and a method of incorporating a hydroxyapatite component as one component of ceramics such as calcium phosphate (Bi
omaterials, Vol. 14, pp. 216-224, 1993) .However, these materials have a high mechanical elastic modulus,
There is a problem that the use application is significantly restricted due to low toughness. In addition, since these materials have mechanical properties different from those of living bones, there is also a problem that danger such as bone resorption cannot be denied due to physical stimulation.

Therefore, as a means for solving these problems, a composite material of hydroxyapatite and a synthetic polymer such as poly-L-lactic acid (Cells Mater.
2, pp. 329-337, 1992), and a composite material of hydroxyapatite and a synthetic polymer such as polyhydroxybutyrate (Biomaterials, Vol. 14, Vol.
793-796, 1993), and a composite material of hydroxyapatite and a biopolymer such as collagen (Biomaterials, Vol. 14, pages 97-106, 1993).
Years) are reported respectively. This is based on the fact that living bone is a complex tissue of hydroxyapatite and collagen, which is a biopolymer, but synthetic polymers such as poly-L-lactic acid or polyhydroxybutyrate are generally used. Because of its poor compatibility with living tissues, the effect on osteoblasts and the like cannot be ignored, and there is a possibility that a problem may occur in osteosynthesis in the long term.

[0007] When collagen, which is a biopolymer having excellent biocompatibility, is used, although the problems of the synthetic polymer can be avoided, collagen is prepared by extraction from animal tissues. Not only does the manufacturing process for the material become complicated, but also the cost of manufacturing the material is high.

On the other hand, silk thread, which is a biopolymer obtained through silkworms, is a material having an appropriate elastic modulus and excellent mechanical properties such as excellent toughness, and has already been produced at the industrial level as a traditional clothing material. .

[0009] In the non-clothing field, as in the case of silk thread, which has been conventionally used as a surgical suture, silk protein is less irritating to living tissues and has excellent cell adhesion and proliferation properties. It is a material with excellent biocompatibility.

[0010] Since the production of cocoons into silk threads is possible on an industrial level, silk proteins can be produced at a lower cost than other biopolymers, and silk proteins can be used to solve the problem of collagen. Suitable as a material.

[0011] However, since silk protein alone has low osseointegrability and is insufficient as an osteosynthetic material,
Development of new utilization technology is desired.

The present invention has an appropriate elastic modulus and toughness,
A modified silk protein having biocompatibility, a simple production process, and a low production cost ;
And an osteosynthetic material using the modified silk protein as a material .

[0013]

SUMMARY OF THE INVENTION One modified silk tamper of the present invention
The protein is attached to the reactive side chain in the silk protein with amino acids.
Succinic anhydride and glutaric anhydride that become ionic groups after the reaction
Acid, phthalic anhydride or O-sulfobenzoic anhydride
By chemical modification processing, or
Phosphoric acid having an ionic group such as an acid group or a sulfate group in the side chain
Methacrylic monomer or styrenesulfonic acid monomer
Introduce the ionic group by grafting with nomer
It is characterized by comprising. Introduction of the ionic group of the present invention
The modified silk protein is made of
Citric acid, glutaric anhydride, phthalic anhydride or O
-Reacting with sulfobenzoic acid, or the silk protein
And the methacrylic phosphate monomer or styrene
By graft polymerization with sulfonic acid monomer,
Obtained.

The osteosynthetic material of the present invention is characterized in that
A modified silk protein having a functional group introduced therein,
Silk protein adsorbs calcium, phosphate and hides
It has the ability to form roxyapatite. Raw materials and
Said silk protein is, for example, fibroin,
Consisting of syn or a mixture of both.
Methacrylic acid-based monomers include, for example, polypropylene
Recall methacrylate acid phosphate
And the styrene sulfonic acid monomer is, for example,
It is sodium p-styrenesulfonate. In addition,
The silk protein used in Ming is cocoon, raw silk, or
Can be obtained by scouring.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various methods have been reported for imparting osteointegration to various materials. In particular, recently, hydroxyapatite, which is a living bone component, is used, for example, with collagen, poly L
-An excellent material can be prepared by mixing with a material such as lactic acid or coating a surface of a material such as a metal or ceramic with hydroxyapatite and fusing it with hydroxyapatite in living bone.

Also, a method of firmly joining the material and the bone tissue by depositing and forming hydroxyapatite on the surface of a material such as high-density polyethylene or polyethylene terephthalate (Polymer Prep)
prints, Japan, vol. 44, p. 1485, 1995
Year) has been reported. This is a promising method for improving the osteointegration of the material by efficiently adsorbing calcium and phosphoric acid, which are the components of hydroxyapatite, on the material and effectively generating hydroxyapatite on the surface or inside of the material. .

The present invention uses chemical modification or grafting as a means for improving the osteointegration of the material.

The modified silk protein of the present invention is chemically modified
Reactive side of silk protein by engineering or grafting
Calcium by chemically bonding ionic groups to the chain,
It has a function of effectively adsorbing phosphoric acid.
The osteosynthetic material of the present invention
It is composed of silk protein. The reactive side chain of the silk protein referred to here means a basic amino acid side chain such as lysine, arginine and histidine, and a side chain having a hydroxyl group such as serine and tyrosine, and the ionic group means aspartic acid and glutamic acid. Etc. means a carboxyl group.

An osteosynthetic material having the ability to form hydroxyapatite in the material by the efficient adsorption of calcium and phosphoric acid by the ionic group used for the modification. The term “modification” as used herein means that new properties are imparted to the silk protein by biochemical or physicochemical properties by chemical modification or grafting.

An osteosynthetic material having the property of effectively adsorbing calcium and phosphoric acid by introducing a polymerizable molecule having an ionic group in the molecular side chain into silk protein. The term "polymerizable molecule having an ionic group in the molecular side chain" as used herein means, for example, a vinyl compound having a carboxyl group, a phosphate group, a sulfate group or the like in the side chain.

As the silk protein used in the present invention, any silk protein may be used as long as it is derived from wild silkworms, such as silkworms, heavenly silkworms, and tussah silkworms. Any known method such as extraction from a silk gland in which a substance to be accumulated is accumulated, or cocoon thread, a method of extracting from silk thread, or a method of separating silk protein such as fibroin or sericin from cocoon thread or raw silk by scouring is used. You may. In particular, it is preferable to use a silk protein derived from the silkworm cocoon from the viewpoint of simplicity of the production process of the method for obtaining a silk protein, or economic efficiency and efficiency.

Examples of the silk protein include fibroin and sericin. To produce the osteosynthetic material, any silk protein may be used, but fibroin, which can be obtained in large quantities through silkworms, is preferred. Further, a mixture of fibroin and sericin may be used as the silk protein.

The chemical modification processing in the present invention means that a reactive amino acid residue such as lysine, arginine, bistidine or the like in a silk protein is reacted with a dibasic acid anhydride such as phthalic anhydride or succinic anhydride having a high reactivity. Means to introduce an ionic group into a chemical compound by a chemical method.

As the reactive material used for the chemical modification, those capable of reacting with amino acids having a reactive side chain such as lysine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, histidine, tyrosine, serine and cysteine in fibroin are used. There is no particular limitation as long as it becomes an ionic group after the reaction, and examples of the chemically modified material suitable for such purposes include succinic anhydride, glutaric anhydride, phthalic anhydride, and O-sulfobenzoic anhydride. No. Further, as the chemical modification processing method, any of known reaction methods may be used.For example, when phthalic anhydride or O-sulfobenzoic anhydride is used, these dibasic acid anhydrides are dissolved and acyl There is no particular limitation as long as the solvent can introduce a group, and N, N-dimethylformamide, dimethylsulfoxide, tetrahydrofuran, pyridine and the like can be mentioned as solvents meeting these purposes.

The reaction temperature at the time of chemically modifying the silk protein is preferably 40 ° C. or higher, and the reaction time is preferably 30 minutes to 3 hours. The reaction temperature and the reaction time may be appropriately set depending on the difference in reactivity of the reactive material for chemical modification used. For example, in the case of phthalic anhydride having low reactivity, the reaction temperature is 70 to 80 ° C., and the reaction time is
In the case of highly reactive O-sulfobenzoic acid for 30 minutes to 5 hours and a reaction temperature of 55 to 70 ° C. and a reaction time of 30 minutes to 3 hours, predetermined chemical modification processing can be performed.

The bath ratio between the silk protein and the solvent is
It is good to set 1: 10-1: 50, preferably 1:30.

After the chemical modification reaction, it is desirable to carry out a washing treatment with a solvent such as isopropanol in order to remove unreacted substances adhering to the silk protein, followed by a boiling treatment with 55 ° C. acetone for 1 hour.

The amount of the ionic group introduced into the silk protein is 1 to 35% by weight, preferably 1 to 20% by weight, based on the weight (dry weight) of the silk protein. If the amount of the ionic group introduced is less than 1% by weight, sufficient osseointegration to the silk protein cannot be provided, and if the amount of the ionic group introduced exceeds 35% by weight, the silk protein mechanical There is a risk that the biocompatibility of the silk protein may be lost due to the deterioration of the biological properties.

The term "grafting" in the present invention means that a monomer such as a vinyl compound having an ionic side chain is graft-polymerized to a silk protein by a grafting technique.

Usually, the grafting solution may be an aqueous solution if it is a water-soluble vinyl compound, or a grafting solution emulsified with an emulsifier such as an ionic surfactant or a nonionic surfactant if it is insoluble in water. Processing solutions can be used. As a specific grafting method, a vinyl compound for grafting is formed into an aqueous solution or an emulsified solution, and the silk protein is immersed in the aqueous solution or the emulsified solution and subjected to a graft polymerization reaction in the presence of a polymerization initiator.

The vinyl compound used for the grafting is not particularly limited as long as an ionic group can be introduced as a result of the grafting.
Those capable of introducing a phosphate group or a sulfate group are preferable, and examples thereof include a styrene sulfonic acid monomer and a methacrylic phosphate monomer.

Further, even for a vinyl compound for grafting which does not have ionic properties, after grafting, the molecular side chains of the graft polymer are chemically modified so that ionic compounds can be incorporated into the silk protein to be grafted. The method of introducing a functional group can also be used in the same manner as a conventionally known grafting method. Further, the amount of the vinyl compound to the silk protein used for the grafting varies depending on the type of the vinyl compound and the degree of the grafting, but if the amount is about 10 to 150% by weight based on the amount of the silk protein, the grafting efficiency is good. Economical grafting is possible.

The surfactant used for dispersing the water-insoluble monomer in water during the grafting is as follows.
The surfactant is not particularly limited as long as it is a surfactant capable of dispersing and emulsifying a poorly water-soluble graft monomer in water.
Nonionic surfactants such as C (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), for example, a mixture of an anionic surfactant and a nonionic surfactant such as brand name Newcalgen (manufactured by Takemoto Yushi Co., Ltd.) Is mentioned.

In the grafting, the polymerization initiator used is not particularly limited as long as it generates a radical active species, and is preferably a water-soluble one, and is preferably a persulfate such as ammonium persulfate or sodium persulfate. Is mentioned. Further, physical methods such as radiation, plasma discharge, corona discharge, and light can be used.

If the amount of the polymerization initiator used is within the range of 1.2 to 3.0% by weight based on the vinyl compound, the inherent properties of the silk protein are not deteriorated.

The polymerization reaction in the grafting process is as follows.
The temperature is gradually raised from room temperature to 60 to 80 ° C in 30 to 60 minutes, and then the polymerization reaction is carried out at a constant temperature of 60 to 80 ° C for 0.5 to 2 hours. If the heating rate exceeds this range, the grafting does not proceed efficiently. Also, the reaction temperature
If the temperature is lower than 60 ° C., the grafting rate decreases, so that economical grafting cannot be performed.
When the temperature exceeds 80 ° C., the reaction control tends to be difficult, and reproducible grafting cannot be performed. If the reaction time is less than 0.5 hours, the grafting rate is reduced, and the desired osteointegration cannot be sufficiently provided.If the reaction time exceeds 2 hours, the silk protein surface To produce a homopolymer, and the grafting effect becomes insufficient.

The silk protein thus chemically modified or grafted has a capability of efficiently adsorbing calcium and phosphoric acid and forming hydroxyapatite as a living bone component. Can be provided.

Hydroxyapatite contains calcium and phosphoric acid as main components and forms one crystal system composed of them. The ability to form hydroxyapatite as used herein refers to the ability to efficiently adsorb and adhere hydroxyapatite components such as calcium and phosphoric acid, and to accumulate hydroxyapatite using them as nuclei.

[0039]

EXAMPLES Hereinafter, specific examples of the present invention will be described together with comparative examples.

Example 1 This example is an example of chemical modification of a silk protein with phthalic anhydride. As a silk protein, a silk feather double with a 14-mom based on the JIS color fastness test method (JIS L 0803) was used, and the following chemical modification with phthalic anhydride was performed.

First, 0.85 g of silk feather double was immersed in a chemically modified solution obtained by dissolving 2.25 g of phthalic anhydride in 15 ml of N, N-dimethylformamide. A chemical reaction was carried out at a temperature of 80 ° C. for 3 hours in the reaction vessel, and phthalic anhydride was reacted with the silk feather. In addition, the bath ratio of silk feather double and dithimerformamide is 1:
It was set to 15.

Next, after the reaction was completed, the chemically-modified silk feathers removed from the chemically-modified processing solution were washed with N, N-dimethylformamide, and subsequently washed with acetone at a temperature of 55 ° C.
Unreacted phthalic anhydride adhering to the silk feathers was removed by boiling for 1 hour to prepare a sample.

The produced sample was subjected to a drying treatment at a temperature of 105 ° C. for 2 hours, and this was designated as Sample No. 1. And sample No.
The chemical modification ratio of the sample No. 1 was determined from the weight difference from the silk feather double before processing and found to be 5.9%.

Example 2 This example is an example of chemical modification of a silk protein with succinic anhydride.

Using a silk feather with a 14-mom according to the JIS color fastness test method (JIS L 0803) as a silk protein, the following chemical modification with succinic anhydride was carried out.

First, 0.51 g of silk feather double was immersed in a chemically modified processing solution in which 1 g of succinic anhydride was dissolved in 10 ml of N, N-dimethylformamide, and the reaction mixture was made of a glass reactor equipped with a back cooler. A chemical reaction was performed in a container at a temperature of 75 ° C. for 90 minutes, and succinic anhydride was reacted with the silk feathers.
In addition, the bath ratio of Kinuha double and dithimerformamide was 1:20.

Next, after the reaction was completed, the chemically modified silk feather doubles taken out of the chemically modified processing solution were washed with isopropanol, and subsequently boiled with acetone at a temperature of 55 ° C. for 1 hour, and then heated at a temperature of 20 ° C. Was thoroughly washed with cold water to remove unreacted succinic anhydride attached to the silk feathers to prepare a sample.

The produced sample was subjected to a drying treatment at a temperature of 105 ° C. for 2 hours, and this was designated as Sample No. 2. And sample No.
The chemical modification ratio was determined from the weight difference between the silk feather double before processing and that of the silk feather doubler, and it was 7.5%.

Example 3 This example is an example of silk protein grafting with polypropylene glycol methacrylate acid phosphate.

As the silk protein, a silk feather with a 14-mom according to the JIS color fastness test method (JIS L 0803) was used, and the following polypropylene glycol methacrylate acid phosphate (trade name, manufactured by Johoku Chemical Co., Ltd.)
JAMP-100).

First, 50% by weight of polypropylene glycol methacrylate acid phosphate (trade name: JAMP-100) was added to 0.34 g of silk feather double, and silk feather double and polypropylene glycol methacrylate acid phosphate (trade name) were used as polymerization initiators. Name JAMP-100)
2.5% by weight of 2,2'-azobis (2-amidinopropane dihydrochloride: manufactured by Wako Pure Chemical Industries, Ltd.) was used as a nonionic surfactant. ) Was immersed in a grafting solution dissolved in 5.3 ml of an aqueous solution containing
The temperature was raised to 45 ° C. in 45 minutes, and the reaction was performed at 80 ° C. for 1 hour to perform grafting. The bath ratio between the silk feathers and the grafting solution was 1:20.

Next, after the reaction was completed, the grafted silk feather doubled taken out of the grafting solution was treated with a 0.4% aqueous solution of Neugen HC (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in an aqueous solution.
After washing at ℃ for 30 minutes, wash thoroughly with cold water at a temperature of 20 ° C and thoroughly attach to silk feathers. Polypropylene glycol methacrylate acid phosphate (trade name: JAMP-100) and a nonionic surfactant A sample was prepared by removing the unreacted substances of the above.

The prepared sample was subjected to a drying treatment at 105 ° C. for 2 hours, and this was designated as Sample No. 3. And sample No.
The grafting ratio of No. 3 was determined from the weight difference from the silk feather double before processing, and was found to be 16%.

Example 4 This example is an example of silk protein grafting with sodium p-styrenesulfonate.

Using a silk feather with a 14-mom according to the JIS color fastness test method (JIS L 0803) as a silk protein, the following grafting treatment with sodium p-styrenesulfonate was performed.

First, 100% by weight of sodium p-styrenesulfonate based on 0.32 g of silk feathers and 2.5% by weight based on the total weight of silk feathers and sodium p-styrenesulfonate as a polymerization initiator 2,2'-azobis (2-amidinopropane dihydrochloride: manufactured by Wako Pure Chemical Industries, Ltd.) was used as a nonionic surfactant at a 0.4% trade name of Neugen HC.
0.32 g of silk feather double was immersed in a grafting solution dissolved in 4.7 ml of an aqueous solution containing (Daiichi Kogyo Seiyaku Co., Ltd.), and the temperature was raised from room temperature to 80 ° C. in 45 minutes. The reaction was allowed to proceed for a time to perform grafting. The bath ratio between the silk feathers and the grafting solution was 1:20.

After completion of the reaction, the grafted silk feathers taken out of the grafting solution were treated with a 0.4% aqueous solution of Neugen HC (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in an aqueous solution of 80%.
30 ° C. for 30 minutes, and then thoroughly washed with cold water at a temperature of 20 ° C. to remove unreacted products of sodium p-styrenesulfonate and nonionic surfactant attached to the silk feathers. To prepare a sample.

The prepared sample was subjected to a drying treatment at 105 ° C. for 2 hours, and this was designated as Sample No. 4. And sample No.
Grafting rate was calculated from the difference in weight between silk feathers 2 and 4 before processing and found to be 6%.

Example 5 This example is an experiment of calcium adsorption on a chemically modified or grafted silk protein.

The calcium adsorption experiment was performed as follows.

First, in Examples 1 and 2, the chemical modification processing was performed.
Alternatively, each sample of silk feathers double-grafted in Examples 3 and 4 (Sample No. 1, Sample No. 2, Sample No. 3, Sample N)
o.4) was cut into a size of 1 cm x 1 cm to obtain a calcium adsorption experiment sample.

Next, each sample was immersed in 10 ml of a simulated body fluid composed of various inorganic salts, and allowed to stand in a thermostat at a temperature of 37 ° C. for 3 days. Three days later, each sample was taken out, washed with water, and dried at room temperature for three days.

The dried sample was subjected to elution treatment with a 1N hydrochloric acid solution at 60 ° C. to extract calcium, and the amount of calcium (mmol / cm ² ) was quantified by a colorimetric method. Table 1 shows the results.

[0064]

[Table 1]

Example 6 This example is an experiment on the adsorption of phosphoric acid to a silk protein that has been chemically modified or grafted.

The phosphoric acid adsorption experiment was performed as follows.

First, in Examples 1 and 2, chemical modification
Alternatively, each sample of silk feathers double-grafted in Examples 3 and 4 (Sample No. 1, Sample No. 2, Sample No. 3, Sample N)
o.4) was cut into a size of 1 cm × 1 cm to obtain a phosphoric acid adsorption experiment sample.

Next, each sample was immersed in 10 ml of a simulated body fluid composed of various inorganic salts, and allowed to stand in a thermostat at a temperature of 37 ° C. for 3 days. Three days later, each sample was taken out, washed with water, and dried at room temperature for three days.

The dried sample was subjected to an elution treatment with a 1N hydrochloric acid solution at 60 ° C. to extract phosphoric acid, and the amount of phosphoric acid was quantified by a colorimetric method. Table 2 shows the results.

[0070]

[Table 2]

Comparative Example 1 An experiment for adsorption of calcium and phosphoric acid on untreated silk protein.

Chemical modification processing as untreated silk protein,
Alternatively, a silk feather double with a 14 momme according to JIS dye fastness test method (JIS L 0803) without any grafting treatment was used, and this was used as Sample Comparative Example 1.

Then, in the same manner as in Example 5, the amount of calcium in Sample Comparative Example 1 was quantified. Table 1 shows the results.

Further, the amount of phosphoric acid in Sample Comparative Example 1 was quantified in the same manner as in Example 6. Table 2 shows the results.

As is clear from Table 1, Sample No. 1
It can be seen that 2, 3, and 4 are materials that adsorb calcium efficiently and are easier to adsorb calcium than Comparative Example 1.

As is clear from Table 2, Sample No. 1
It can be seen that 2, 3, and 4 are materials that adsorb phosphoric acid efficiently and are easier to adsorb phosphoric acid than Comparative Example 1.

Example 7 This example is an example using silkworm silk fibroin fiber (silkworm silk) as silk protein.

The silkworm cocoon was boiled with a 0.2% by weight aqueous solution of sodium carbonate at 98 ° C. for 45 minutes to remove sericin on the silkworm cocoon surface and refined to produce silkworm silk fibroin fiber (silkworm silk).

Using the produced silkworm silk fibroin fiber (silkworm silk), a chemical modification process was performed in the same manner as in Examples 1 and 2, or a grafting process was performed in the same manner as in Examples 3 and 4. Then, a silk fibroin fiber having the same chemical modification rate or graft processing rate as that of the corresponding example was prepared.

Each of the prepared fibers was used as a sample No. 5, No.
6, No. 7, and No. 8.

Then, the mechanical properties (strength, elongation) of each fiber were measured. Table 3 shows the obtained results.

The mechanical properties (strength and elongation) of Comparative Example 1 and other materials were also measured. Table 3 also shows the obtained results.

The sample N was prepared in the same manner as in Example 5.
When the amounts of calcium of o.5 and sample No.7 were quantified, sample No.5 was equivalent to sample No.1, and sample No.7 was equivalent to sample No.3.

The sample N was prepared in the same manner as in Example 6.
When the amounts of phosphoric acid in o.5 and sample No.7 were quantified, sample No.5 was equivalent to sample No.1, and sample No.7 was sample N
It was equivalent to o.3.

[0085]

[Table 3]

As is clear from Table 3, the chemical modification processing
Alternatively, the strength of the grafted silk protein of the present invention is close to that of a living bone, and in particular, it has mechanical properties equivalent to those of a living tendon, indicating that it is excellent as an osteosynthetic material.

The present invention is not limited to these embodiments.

As described above, the osteosynthetic material of the present invention has an improved ability to adsorb calcium and phosphate by chemically bonding an ionic group to the reactive side chain of the silk protein by chemical modification or grafting. Bone-binding material, ionic group used for modification Adsorbs calcium and phosphoric acid efficiently, so that bone-binding material capable of forming hydroxyapatite in material, ionic group is converted to molecular side chain This is an osteosynthetic material whose calcium and phosphate adsorption capacity has been modified by introducing its polymerizable molecules into silk proteins.

[0089]

According to the osteosynthetic material of the present invention, an osteosynthetic material having a moderate elasticity and tough mechanical properties, and a biocompatible silk protein having the osteosynthetic properties. Has the effect of providing. In addition, this osteosynthetic material efficiently adsorbs calcium and phosphoric acid, has the ability to form hydroxyapatite as a bone component on the surface and inside of the osteosynthetic material, and strongly binds to bone tissue. In addition, since silk protein is excellent in cell attachment and proliferation, it is effective for bone formation, and it becomes a good scaffold for fibroblasts, etc.
It can also be used as a joining material for soft tissue such as muscle and hard tissue such as bone. From these characteristics, the osteosynthetic material of the present invention can be used as a material for artificial tendons and artificial ligaments, which has been difficult with conventional materials such as metals and ceramics, and has a great effect on medical treatment. Is to give.

According to the method for producing an osteosynthetic material of the present invention, an osteosynthetic material obtained by imparting osteosynthetic characteristics to a biocompatible silk protein having appropriate elasticity and tough mechanical properties. There is an effect that the material can be easily manufactured at low cost.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61L 27/00 A61K 6/08 A61L 25/00

Claims (6)

(57) [Claims] (1) An amino group is added to a reactive side chain in a silk protein.
Succinic anhydride, glucan anhydride, which becomes an ionic group after reaction with acid
Talic acid, phthalic anhydride, or O-sulfobenzoic anhydride
Chemical modification by acid or carboxyl
Having ionic groups such as phosphate group, phosphate group and sulfate group in the side chain
Methacrylic phosphate monomer or styrene sulfo
The ionic group by grafting with an acid monomer
A modified silk protein, characterized by being introduced with: 2. The method according to claim 1, wherein the silk protein is fibroin,
Lysine, or a mixture of both,
Methacrylic phosphate monomer is polypropylene glycol
Methacrylate acid phosphate.
The styrene sulfonic acid monomer is p-styrene
2. The composition according to claim 1, which is sodium sulfonate.
The modified silk protein shown. 3. A silk protein, comprising : a silk protein;
Succinic anhydride, which becomes an ionic group after reaction with amino acid, anhydride
Glutaric acid, phthalic anhydride, or O-sulfoanhydride
Reacting with benzoic acid, or
Ionic, such as xyl, phosphate, or sulfate
Methacrylic acid-based monomer having a group in the side chain, or
Graft polymerization with a styrene sulfonic acid monomer,
Modified silk tamper by introducing the ionic group into a silk protein
A method for producing a modified silk protein , characterized in that a modified silk protein is obtained . 4. The method according to claim 1, wherein the silk protein is fibroin,
Lysine, or a mixture of both,
Methacrylic phosphate monomer is polypropylene glycol
Methacrylate acid phosphate.
The styrene sulfonic acid monomer is p-styrene
4. The composition according to claim 3, which is sodium sulfonate.
The method for producing the modified silk protein described above. 5. An amino group is added to a reactive side chain in a silk protein.
Succinic anhydride, glucan anhydride, which becomes an ionic group after reaction with acid
Talic acid, phthalic anhydride, or O-sulfobenzoic anhydride
Chemical modification by acid or carboxyl
Having ionic groups such as phosphate group, phosphate group and sulfate group in the side chain
Methacrylic phosphate monomer or styrene sulfo
The ionic group by grafting with an acid monomer
And a modified silk protein comprising
The protein adsorbs calcium and phosphoric acid and
Osteosynthesis characterized by the ability to form sheapatite
Material. 6. The method according to claim 6, wherein the silk protein is fibroin,
Lysine, or a mixture of both,
Methacrylic phosphate monomer is polypropylene glycol
Methacrylate acid phosphate.
The styrene sulfonic acid monomer is p-styrene
6. The composition according to claim 5, which is sodium sulfonate.
Osteosynthetic material.