JP5110046B2 - Polysaccharide complex and method for producing the same - Google Patents

Description

  The present invention relates to a complex of a polysaccharide derived from a natural product having excellent biodegradability and biocompatibility, and relates to a simple production method in an aqueous system.

  In recent years, natural polysaccharides have attracted attention as new types of biodegradable polymer materials and biocompatible materials, and many studies have been made on their use, and various findings have been reported.

In particular, chitin and chitosan are attracting attention as biocompatible materials having bioactive effects.
Chitosan exists as a skeletal substance of crustaceans such as crabs and shrimps, insects such as beetles and crickets, and also exists in fungi and cell walls (there are many N-acetyl D-glucosamine residues, β- (1, 4) -linked polysaccharide), which is a β- (1,4) -linked polysaccharide of glucosamine and is also used as the only natural cationic polysaccharide.

  On the other hand, a polyion complex material composed of a polycationic substance and a polyanionic substance can be easily prepared in an aqueous system, and a substance insoluble in water can be obtained. 100468, JP-A-7-33682, JP-A-11-130697, JP-A-2002-638, etc.). For example, natural products such as hyaluronic acid, chondroitin, chitin, chitosan, sodium alginate, pectin, dextran, etc., and other derivatives such as carboxymethylcellulose, gelatin, polyamino acids and polypeptides and proteins, There are polyion complexes using synthetic polymers such as acrylic acid.

However, the synthetic polymer can control the cationic group or anionic group in the molecule, and it is easy to prepare polyion complexes with various physical properties, but it is poor in biodegradability and biocompatibility, and its application range is limited. Is done.
In addition, natural materials with excellent biodegradability and biocompatibility, protein materials have the risk of viral infections derived from humans and animals, and natural polysaccharides have cationic or anionic functional groups due to natural products. It cannot be controlled and has a drawback that it is difficult to form a polyion complex corresponding to various required physical properties.
Furthermore, in conventional polysaccharide derivatives such as carboxymethylcellulose, even if the degree of substitution can be controlled, the distribution of substituents within the molecule or between molecules is not uniform, and the mechanism of degradation and metabolism in vivo is not clear. It had the problem that.

JP 2000-5296 A JP-A-10-279604 Japanese Patent Laid-Open No. 11-21302 JP 2001-49591 A International Publication No. 95/7303

  The object of the present invention is that it has good processability, can be obtained easily and inexpensively by a simple purification process, has a uniform structure, can control carboxyl groups and amino groups that form ion complexes, and can be controlled by additives. An object of the present invention is to provide a polysaccharide complex having a suitable performance and excellent in biocompatibility and biodegradability, and a production method thereof.

The invention of claim 1 is a method for producing a polysaccharide complex comprising at least an oxidized polysaccharide and chitosan, wherein the oxidized polysaccharide introduces a carboxyl group or a salt thereof into the 6-position of the pyranose ring of the polysaccharide by oxidation. It is an oxidized polysaccharide, and dissolves the oxidized polysaccharide, the chitosan, and at least one additive selected from a porous agent, a crosslinking agent, a decomposition accelerator, a coupling agent, an extender, and an antibacterial agent. Alternatively, a step of preparing the dispersed solution and neutralizing the solution with an acid or an alkali to produce a salt for making the polysaccharide complex into a porous structure, and a polyion of oxidized polysaccharide and chitosan And a process for forming a complex and insolubilizing with water.

The invention of claim 2 is obtained by a method in which the oxidized polysaccharide is obtained by a method of oxidizing a polysaccharide dissolved or dispersed in water in an aqueous system using an oxidizing agent in the presence of a catalyst of an N-oxyl compound. a method for producing a polysaccharide conjugate of claim 1, wherein the formed by selectively oxidizing the primary hydroxyl group of the polysaccharide pyranose ring in the 6-position.

The invention according to claim 3, as the chitosan, the ratio of its constituent glucosamine and N- acetylglucosamine monosaccharides, 45: claim 1 or claim 2, characterized in that in the range of 55 55:45 It is a manufacturing method of the polysaccharide complex of description.

The invention of claim 4 is a polysaccharide complex produced by the method for producing a polysaccharide complex according to any one of claims 1 to 3 .

According to the present invention, a water-insoluble polysaccharide complex can be obtained easily and inexpensively by a simple method, and further, the physical properties, structure, and performance of the polysaccharide complex can be obtained by including a modifying additive. , And processability can be easily modified. The polysaccharide complex of the present invention is a polyion complex composed of chitosan made of N-acetylglucosamine and glucosamine because it is a natural ion and an oxidized polysaccharide having a uronic acid structure with a controlled chemical structure. Since it is decomposed and has high biocompatibility, it can be used as a pharmaceutical for oral administration, a pharmaceutical for percutaneous absorption, a medical material used in vivo in a surgical operation, and a pesticide, food, cosmetics and the like.
Furthermore, in the present invention, unlike a polyion complex made of a conventional natural product material, the carboxyl group and amino group forming the polyion complex can be controlled, so the structure is clear and highly safe, the physical properties of the polysaccharide complex, etc. It is possible to control various required characteristics.
Furthermore, according to the present invention, by using a COOH-type oxidized polysaccharide and water-soluble chitosan having a controlled acetylation rate, it is possible to make a complex including an additive component in a neutral region, and it is possible to use an acid or an alkali. A neutralization treatment is not required, the influence of the salt can be eliminated, and a complex that is completely water-soluble in both acidic and alkaline regions can be obtained.

1 is a chemical structural formula showing an example of the polysaccharide complex of the present invention. It is the 13C-NMR spectrum measured by melt | dissolving the sodium amyluronate used for this invention in heavy water, and the 13C-NMR spectrum measured by melt | dissolving the raw material starch in heavy water. It is the spectrum of 13C-NMR measured by melt | dissolving the sodium celouronic acid salt used for this invention in heavy water. It is the spectrum of 13 C-NMR measured by dissolving chitouronic acid sodium salt used in the present invention in heavy water. It is a 1H-NMR spectrum measured by dissolving 30% N-acetylated chitosan used in the present invention in a deuterated aqueous solution of deuterated hydrochloric acid. It is a 1H-NMR spectrum measured by dissolving 50% N-acetylated chitosan used in the present invention in a deuterated aqueous solution of deuterated hydrochloric acid. It is a 1H-NMR spectrum measured by dissolving 50% N-acetylated chitosan used in the present invention in heavy water. It is a 1H-NMR spectrum measured by dissolving 60% N-acetylated chitosan used in the present invention in an aqueous solution of deuterated hydrochloric acid. It is a graph which shows the biodegradation degree measured according to Test Example 1 of the oxidation polysaccharide used for this invention, and chitosan.

Details of the present invention will be described below.
The polysaccharide complex of the present invention comprises N-acetylglucosamine, which is a constituent monosaccharide, using an oxidized polysaccharide in which a carboxyl group or a salt thereof is introduced at the 6-position of the pyranose ring of the polysaccharide by a highly selective oxidation method as a polyanion component. It is characterized in that chitosan having a controlled ratio of glucosamine is used as a polycation component to form a polyion complex of both, and comprises one or more polysaccharide modifying additives and / or modifying additive components To do.

  First, the oxidized polysaccharide serving as a polyanion component for forming a polyion complex in the present invention will be described. The oxidized polysaccharide used in the present invention is a polysaccharide having a uronic acid structure in which the 6-position of the pyranose ring of a natural polysaccharide is selectively oxidized and a carboxyl group or a salt thereof is introduced. There are no particular restrictions on the type and origin of natural polysaccharides used as raw materials. However, cellulose, chitin, starch, etc., in which almost single constituent monosaccharides are linked in a straight chain, are used to procure raw materials and oxidize. This is particularly preferable from the viewpoint of ease of treatment and safety of uronic acid produced by oxidation.

Unlike the introduction of a carboxyl group by derivatization into a polysaccharide such as carboxymethylation, the oxidized polysaccharide used in the present invention has a carboxyl group selectively introduced at the 6-position only in one pyranose ring, Since the distribution between the molecules and within the molecule is uniform and the substituent is not introduced into the hydroxyl group by an ester bond or an ether bond, the influence of steric hindrance when forming the polyion complex is small. Moreover, there is no influence of the substituent after being decomposed in vivo and in vitro. For example, oxidized cellulose is called celouronic acid, and glucuronic acid is linked by β-1,4 bonds. Oxidized starch is called amylouronic acid, and glucuronic acid is linked by α-1,4 bonds. Oxidized chitin is called chitouronic acid or 6-oxychitin, and N-acetylglucosaminouronic acid (the 6th carbon of N-acetylglucosamine becomes a carboxyl group) is linked to β-1,4 It is connected with.

  Naturally, there are uronic acids such as alginic acid, pectin, and hyaluronic acid, but there are mainly heteropolysaccharides, and because of natural products, there are many uncontrollable parts such as the distribution of sugar residues and the effects of introduced side chains, The polyanion component of the present invention is not preferred. One feature of the polyanion component used in the present invention is that it is an oxidized polysaccharide in which the degree of oxidation is controlled to control the proportion of uronic acid.

Hereinafter, the oxidation method for obtaining the oxidized polysaccharide of the present invention will be described.
The oxidation method in the present invention is characterized in that a polysaccharide dissolved or dispersed in water is treated in an aqueous system in the presence of a catalyst such as an N-oxyl compound, and the 6-position of the pyranose ring of the polysaccharide is selected. It can be oxidized to introduce a carboxyl group or a salt thereof.

  The oxidized polysaccharide of the present invention can be obtained by oxidizing a raw material polysaccharide using an oxidizing agent in the presence of an N-oxyl compound (oxoammonium salt). Examples of the N-oxyl compound include 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (hereinafter referred to as TEMPO). In this oxidation method, carboxyl groups can be uniformly and efficiently introduced according to the degree of oxidation. The N-oxyl compound may be used in an amount as a catalyst. For example, 10 ppm to 5% is sufficient with respect to the number of moles of the constituent monosaccharide of the polysaccharide, but 0.05% to 3% is preferable.

  As the oxidizing agent, halogen, hypohalous acid, halohalic acid, perhalogenic acid or salts thereof, halogen oxide, nitrogen oxide, peroxide, etc., as long as the oxidizing agent can promote the target oxidation reaction Any oxidizing agent can be used.

  Furthermore, in this oxidation method, when the oxidation reaction is carried out in the presence of bromide or iodide, the oxidation reaction can proceed smoothly even under mild conditions, and the introduction efficiency of the carboxyl group can be greatly improved. The amount of bromide or iodide used can be selected within a range that can promote the oxidation reaction, and is, for example, 0 to 100% with respect to the number of moles of constituent monosaccharides of the polysaccharide. However, 1 to 50% is preferable from the viewpoint of reaction efficiency.

  In the polysaccharide oxidation method of the present invention, for example, it is particularly preferable to use TEMPO as the N-oxyl compound and sodium hypochlorite as the oxidizing agent in the presence of sodium bromide.

  In addition, for the purpose of increasing the selectivity of oxidation of the constituent monosaccharide residue to the primary hydroxyl group and suppressing side reactions, it is desirable to carry out the reaction at a reaction temperature of room temperature or lower, more preferably 5 ° C. or lower. Furthermore, it is preferable to keep the inside of the system alkaline during the reaction. The pH at this time is 9-13, more preferably pH 10-12.

Here, this oxidation method is characterized in that the degree of oxidation can be controlled by the amount of alkali added when the pH is kept at a constant value. When the amount of alkali added is 1 mol with respect to 1 mol of a sugar residue, the primary hydroxyl group at the 6-position in all the sugar residues is oxidized to a carboxyl group.
Therefore, if the amount of alkali or the oxidizing agent added is reduced and the amount of carboxyl groups introduced is reduced, the number of contact points between the oxidized polysaccharide and chitosan when forming a polyion complex is reduced, and the physical properties of the polysaccharide complex are reduced. Can be controlled.

  In addition, when the polysaccharide as a raw material has high crystallinity, the oxidation efficiency is deteriorated. However, the oxidation efficiency can be improved by dissolving it once in each soluble solvent and performing a regeneration treatment.

  Further, the 6-position carboxyl group of the oxidized polysaccharide is more stable when it exists as a salt such as a sodium salt, and these oxidized polysaccharide salts are highly water-soluble. Further, a desalted COOH-type oxidized polysaccharide can be obtained by adding an acid such as hydrochloric acid to the aqueous solution of the oxidized polysaccharide salt or treating with an ion exchange resin. In particular, the above-mentioned amylouronic acid and chitouronic acid (or 6-oxychitin) are water-soluble even in the COOH type.

Subsequently, chitosan serving as a polycation component for forming a polyion complex in the present invention will be described.
N-acetylglucosamine and polysaccharides in which glucosamine is β-1,4 glycosidic bonded, generally having a high glucosamine ratio is called chitosan, and having a high N-acetylglucosamine ratio is called chitin. Chitin is present in the cell walls of fungi and the like as skeleton materials for straw and shrimp, and is obtained through purification processes such as decalcification, protein removal, lipid and pigment removal. Alternatively, the chitin obtained in the above step is generally obtained by further hydrolyzing with an acid or alkali and subjecting it to a deacetylation treatment. Further, N-acetylglucosamine and glucosamine, which are constituent monosaccharides, exist also in the living body, and are easily decomposed in and out of the living body, and it can be said that their safety is high.

  As chitosan used in the present invention, the above-mentioned general chitosan can be applied, and the raw material, purification method, degree of polymerization, etc. are not particularly limited. The proportion of glucosamine in the constituent monosaccharide is desirably 20 to 100%. Since glucosamine has a cationic free amino group, this ratio is an important factor in controlling the physical properties of the polysaccharide complex of the present invention.

  The ratio of N-acetylglucosamine and glucosamine, that is, the ratio of N-acetyl group and amino group is controlled by deacetylation by hydrolysis with acid or alkali, or conversely by N-acetylation method using acetic anhydride or the like. Is possible. In the deacetylation reaction, the amino group ratio can be controlled by the hydrolysis reaction time, and in the N-acetylation reaction, the amount of reagent added.

  Here, chitosan forms a salt in a dilute acid solution and dissolves, but it is insoluble in water from neutral to alkaline. However, it is known that the ratio of glucosamine to N-acetylglucosamine is soluble in water in a wide pH range in the range of 45:55 to 55:45. When preparing this water-soluble chitosan, it is important to perform N-acetylation or deacetylation in a homogeneous system.

  Since this water-soluble chitosan is soluble in water in a wide pH range, it dissolves not only in an acidic solution but also in an aqueous solution showing the alkalinity of the uronic acid salt, and even in an alkaline aqueous solution, a complex with a uniform distribution of uronic acid and chitosan is formed. Can be manufactured.

  In addition, this water-soluble chitosan dissolved in water without a counterion and a complex in which a polyion complex is formed using the COOH type of uronic acid do not require the work of removing the counterion and can shorten the process. At the same time, there is no influence of salt in the living body.

  Here, the ratio of glucosamine and N-acetylglucosamine in chitosan is generally deacetylation degree or N-acetylation degree ((N-acetylation degree (%)) = 100%-(deacetylation degree (%))). ), But can be determined by colloid titration, infrared spectroscopy (IR) by the KBr tablet method, or nuclear magnetic resonance spectroscopy (NMR) dissolved in an acidic solution.

  In the present invention, a polysaccharide modifying additive and / or a modifying additive component may be included in the polysaccharide complex. The modifying additive is not particularly limited as long as it is added for the purpose of modifying the composite physical properties, structure, performance, and processability. , Crosslinking agent, surfactant, water-resistant agent, water repellent, filler, decomposition accelerator, adhesive, plasticizer, coupling agent, antibacterial agent, softener, lubricant, extender, colorant, UV absorber Or an additive component made of a mixture thereof, and is selected according to the required physical properties. Moreover, including these additives and / or an additive component means the state in which the additive and / or additive component is contained in the composition by adding to the polysaccharide complex. In addition, these additives and / or additive components may or may not be integrated with the polysaccharide complex. Further, the additive and / or the additive component may be contained at least once, and may be modified by adding and then removing.

For example, a porosifying agent can be added to the composite to improve the elongation and flexibility of the multi-composite. Supporting a hollow, sponge-like structure on a composite is also one method of adding a porosifying agent. Further, when a complex is produced by neutralization, a counter ion of a carboxyl group or amino group generates a salt. This salt is uniformly dispersed in the composite and can be removed by subsequent water washing. The composite from which the salt has been removed is porous, and is imparted with physical properties such as large elongation and high flexibility as compared with a composite that is not porous. These salts can also be said to be a porous agent.
Moreover, in order to strengthen the bond in the complex and increase the strength, a crosslinking agent can be added and included in the polysaccharide. The type and form of the crosslinking agent such as carbodiimide and epoxy crosslinking agent are not particularly limited, and are selected according to the required physical properties and purpose.
In addition, various decomposition accelerators can be added to the complex in order to improve the decomposability of the complex. Examples of the decomposition accelerator include enzymes and starch.

  The polysaccharide complex of the present invention comprises the above-mentioned three components of oxidized polysaccharide, chitosan, and additive component as essential components, in addition to pharmaceutical components, agricultural chemicals, antibacterial agents, fungicides, insect repellents, fragrances, and deodorants. It may contain a medicinal component such as an agent and a deodorant, a component for adjusting the medicinal effect, a component that is secondarily generated when forming a polyion complex, and the like. In addition, the above three essential components may be used alone or in combination of two or more. Furthermore, the mixing ratio of each component is not particularly limited as long as it is within the range of forming a polyion complex, and should be adjusted according to the required physical properties.

Further, in order to complex the oxidized polysaccharide and chitosan forming the complex at the molecular level, it is preferable to dissolve in an appropriate solvent to form a polyion complex. In the present invention, it is particularly preferable to use water as a medium, and an organic solvent such as alcohol or acetone can be added as necessary. The concentration of the oxidized polysaccharide, chitosan or additive in the solution is not particularly limited as long as these complexes are formed, and can be selected according to the required characteristics of the complex.
The method for forming the polyion complex of the polysaccharide complex of the present invention is exemplified below.

  The first method is to add a powder or aqueous solution of the oxidized polysaccharide or a salt thereof and a powder or aqueous solution of the chitosan or a salt thereof to an aqueous solution in which an additive component is dissolved or dispersed. Forms a polyion complex and becomes insoluble in water. At this time, the additive component existing in the solution in advance is taken into the polysaccharide complex, and the polysaccharide complex of the present invention including the additive component is obtained. If necessary, the salt between counter ions can be removed by washing with water. In order to obtain a uniform polysaccharide complex, it is preferable to mix with sufficient stirring.

  In the second method, first, a solution in which the oxidized polysaccharide, the chitosan, and the additive component are dissolved or dispersed together is prepared, and neutralized with an acid or an alkali while thoroughly stirring, whereby the oxidized polysaccharide and The polysaccharide complex of the present invention can be obtained by forming a polyion complex of chitosan to insolubilize in water and including an additive component. If necessary, the salt generated by neutralization can be removed by washing with water. The method for neutralization is not particularly limited, and can be selected according to the required characteristics of the composite.

  Oxidized polysaccharides dissolve in a wide pH range, and therefore dissolve in acidic solutions. Therefore, when an oxidized polysaccharide is added to an acidic aqueous solution of chitosan and dissolved in powder or aqueous solution, an acidic aqueous solution in which both polysaccharides are dissolved can be prepared. Conversely, water-soluble chitosan having a degree of deacetylation of 45 to 55% dissolves in water in a wide pH range, so that powdered or aqueous solution of water-soluble chitosan is added and dissolved in an alkaline aqueous solution of oxidized polysaccharide. An alkaline aqueous solution in which both polysaccharides are dissolved can be prepared. Accordingly, it is possible to select acidic and alkaline liquid properties according to the characteristics of the additive component to be added.

  Since the polysaccharide complex obtained by this method forms a polyion complex from a solution in which both cationic and anionic polysaccharides are uniformly dispersed, the complex of the contained polysaccharides becomes a more uniform complex. Furthermore, since this polysaccharide complex has a porous structure, it has characteristics such as large tensile elongation when swollen in water.

  Further, the third method is characterized in that an aqueous solution in which the oxidized polysaccharide and the chitosan are dissolved or dispersed is separately prepared in advance, and each aqueous solution is mixed to form a polyion complex. is there. At this time, the additive component is prepared separately from one or both of both polysaccharide solutions or both aqueous solutions and mixed to obtain a polysaccharide complex including the additive component.

  Here, when a water-soluble chitosan having a deacetylation degree of 45 to 55% as chitosan and a COOH type in which a counter ion is removed in advance as an oxidized polysaccharide are mixed with each other to form a polyion complex, This is particularly preferable because there is no production of salt, no salt removal work is required, and there is no influence of salt in vivo.

  The method of mixing the aqueous solution is not particularly limited, and can be selected according to the required characteristics of the composite. For example, a method of casting one solution of oxidized polysaccharide or chitosan to form a dry film and then casting the other solution thereon to form a polyion complex at the interface can also be applied.

  Although the three methods for producing the polysaccharide complex of the present invention have been described in detail above, a polyion complex is further formed from the oxidized polysaccharide and the chitosan, and then the additive solution is applied and immersed in the additive solution. Alternatively, the additive component may be supported on the polysaccharide complex by pasting the additive component together.

In addition, the polysaccharide complex of the present invention can be dried as necessary. Since the dried composite does not dissolve in water but swells, the dried composite can be swollen with a solvent such as water to change its shape, or to be laminated or laminated.
The shape of the polysaccharide complex can be arbitrarily selected from sponge, plate, film, granule, fiber, gel, flake, powder and the like.

The polysaccharide complex of the present invention thus obtained is an additive component in a matrix of a polysaccharide complex in which an ion complex structure is formed by COO- derived from oxidized polysaccharide and NH3 + derived from chitosan as shown in FIG. Is included.
The polysaccharide complex of the present invention comprises a natural polysaccharide, a highly biocompatible uronic acid, N-acetylglucosamine and glucosamine, and is easily biodegraded or metabolized. It can be used as a medicinal product, a medical material used in vivo in a surgical operation, an agrochemical, food, cosmetics, and the like. Furthermore, in the present invention, the carboxyl group and amino group forming the polyion complex can be controlled, and the physical characteristics and the like of the polysaccharide complex can be easily controlled, making it possible to meet various required characteristics.

  Hereinafter, the present invention will be specifically described based on examples.

<Production Example 1>
(Preparation of oxidized starch (amylouronate sodium salt))
A commercially available starch was used as the starch. 5 g of starch is dissolved in 100 ml of water by heating and allowed to cool. To this starch solution, an aqueous solution in which 0.1 g of TEMPO and 1.25 g of sodium bromide were dissolved was added. Next, the reaction system was cooled, 50 g of an aqueous sodium hypochlorite solution (Cl = 5%) was added, and an oxidation reaction was started. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75. When the alkali addition amount corresponding to 100% of the total number of moles of the primary hydroxyl group at the 6-position is reached, ethanol is added to stop the reaction, and water: alcohol = 2: 8. After thoroughly washing with the solution, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain a white powdery oxidized starch having a degree of oxidation of 100% (FIG. 2).

<Production Example 2>
(Preparation of oxidized cellulose (soluuronic acid sodium salt))
Commercially available regenerated cellulose was used as the raw material cellulose. 5 g of cellulose was suspended in 350 ml of water. An aqueous solution in which 0.1 g of TEMPO and 1.25 g of sodium bromide were dissolved was added to this cellulose solution. Next, the reaction system was cooled, 50 g of an aqueous sodium hypochlorite solution (Cl = 5%) was added, and an oxidation reaction was started. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75. When the alkali addition amount corresponding to 100% of the total number of moles of the primary hydroxyl group at the 6-position is reached, ethanol is added to stop the reaction, and water: alcohol = 2: 8. After thoroughly washing with the solution, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain a white powdery oxidized cellulose having a degree of oxidation of 100% (FIG. 3).

<Production Example 3>
(Preparation of oxidized cellulose (sodium salt) having an oxidation degree of 60%)
The same adjustment as in Preparation 1 for oxidized cellulose was repeated except that the sodium hypochlorite aqueous solution was changed to 30 g, and the oxidation reaction was started. The reaction was stopped when the 0.5N-NaOH aqueous solution added to maintain the pH reached 37 ml (60 mol% sodium hydroxide with respect to the number of moles of glucose residues). Thereafter, washing similar to the preparation of oxidized cellulose was repeated to obtain oxidized cellulose (sodium salt) having an oxidation degree of 60%.

<Production Example 4>
(Preparation of oxidized chitin (chitouronic acid sodium salt))
The chitin used as a raw material was a commercially available chitin obtained from cocoon shellfish through steps such as decalcification, protein removal, lipid and pigment removal.
Chitin was immersed in 10 g of a 45% sodium hydroxide aqueous solution 150 g and stirred at room temperature or lower for 2 hours. To this, 850 g of crushed ice and the surroundings were cooled with ice water or the like and added with stirring. Chitin is almost dissolved by this alkali treatment. A sample that was neutralized with hydrochloric acid, thoroughly washed with water, and not dried was used as a sample.
An aqueous solution in which 0.1 g of TEMPO and 1.25 g of sodium bromide were added to 100 g of this 5% chitin suspension was prepared so that the concentration with respect to the total solid weight of chitin was about 2 wt%. Next, the reaction system was cooled, 35 g of a sodium hypochlorite aqueous solution (Cl = 5%) was added, and an oxidation reaction was started. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75. When the alkali addition amount corresponding to 100% of the total number of moles of the primary hydroxyl group at the 6-position is reached, ethanol is added to stop the reaction, and water: alcohol = 2: 8. After thoroughly washing with the solution, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain white powdery chitin oxide having a degree of oxidation of 100% (FIG. 4).

<Production Examples 5-8>
(Preparation of COOH type of oxidized polysaccharide)
The oxidized polysaccharides of Production Examples 1 to 4 are isolated as sodium salts. Each of these powders was made into a 2% aqueous solution, and the pH was adjusted to 1 using hydrochloric acid. Precipitate filtration with excess ethanol, sufficiently desalted with a solution of water: acetone = 1: 7, dehydrated with acetone, dried under reduced pressure at 40 ° C., and each of the oxidized polysaccharides (amiuronic acid, ceurouronic acid, A COOH type of oxidized cellulose (chitouronic acid having an oxidation degree of 60%) was obtained.

<Production Example 9>
(Preparation of chitosan with N-acetylation degree of 30%)
5 g of chitosan having a degree of deacetylation of 100% was dissolved in 95 g of 10% acetic acid, diluted with 500 g of methanol, 0.95 g of acetic anhydride was added with stirring, and the mixture was stirred at room temperature for 15 hours. When a 2N-NaOH aqueous solution is added and neutralized, flakes are precipitated, which is filtered, thoroughly washed with a solution of methanol and water: acetone = 1: 7, dehydrated with acetone, and dried at 40 ° C. under reduced pressure. As a result, flaky chitosan having a N-acetylation degree of 30% was obtained (FIG. 5).

<Production Example 10>
(Preparation of water-soluble chitosan having an N-acetylation degree of 50%)
5 g of chitosan having a degree of deacetylation of 100% was dissolved in 95 g of 10% acetic acid, diluted with 500 g of methanol, 1.59 g of acetic anhydride was added with stirring, and the mixture was stirred at room temperature for 15 hours. When a 2N-NaOH aqueous solution is added and neutralized, flakes are precipitated, which is filtered, thoroughly washed with a solution of methanol and water: acetone = 1: 7, dehydrated with acetone, and dried at 40 ° C. under reduced pressure. Thus, flaky chitosan having a N-acetylation degree of 50% was obtained (FIGS. 6 and 7). This chitosan was water-soluble and had a pH of 8.2 with a 1 wt% aqueous solution. Furthermore, even if acid and alkali were added and pH was changed, it was melt | dissolving.

<Production Example 11>
(Preparation of N-acetylated 60% chitosan)
When 5 g of chitosan with a degree of deacetylation of 100% was dissolved in 95 g of 10% acetic acid, diluted with 500 g of methanol, and 1.90 g of acetic anhydride was added while stirring, gelation took about 1 hour, but it was allowed to stand at room temperature for 15 hours I put it. 2N-NaOH aqueous solution was added for neutralization and filtration. After thoroughly washing with a solution of methanol and water: acetone = 1: 7, dehydrated with acetone, dried under reduced pressure at 40 ° C., and flaky N -Chitosan having a degree of acetylation of 60% was obtained (Fig. 8).

<Test Example 1>
For the oxidized polysaccharides of Production Examples 2, 4, 6 and N-acetylated chitosan of Production Examples 9, 10 and microcrystalline cellulose powder, and carboxymethylcellulose sodium salt with a substitution degree of 0.7, Biodegradability by aerobic microorganisms in soil was evaluated. The results are shown in FIG. It can be seen that carboxymethylcellulose sodium salt hardly decomposes, whereas oxidized polysaccharides and chitosan as raw materials of the present invention decompose substantially in the same manner as cellulose.

(Evaluation method for biodegradability)
Using a microbial oxidative degradation measuring device (MODA) manufactured by Yawata Bussan Co., Ltd., standard compost (YK-2 manufactured by Yawata Bussan Co., Ltd.) 250 cc adjusted to 60% moisture and adjusted to 18% moisture as test soil. A mixture of 250 cc of sea sand was used. 10 g of the sample was uniformly mixed with the test soil, filled in a column-shaped reaction cylinder, and the temperature in the reaction cylinder was kept constant at 35 ° C. Further, decarboxylated air saturated with water vapor is vented at 40 ml / min from the bottom of the reaction cylinder, and the gas is not leaked from the top of the reaction cylinder, passes through a sulfuric acid bath to remove ammonia gas, and silica gel to remove moisture. And the moisture absorption cylinder filled with calcium chloride, and further led to the absorption cylinder filled with soda talc and soda lime. Since all the carbon dioxide generated by aerobic biodegradation of the sample is absorbed by the absorption cylinder, the amount of carbon dioxide generated by biodegradation can be quantified from the weight change of the absorption cylinder. In addition, the blank test of only the test soil which does not put a sample was performed simultaneously, and the amount of carbon dioxide generated by decomposition was calculated by subtracting the amount of carbon dioxide generated in the blank test. The theoretically generated carbon dioxide amount is calculated from the carbon content in 10 g of the sample, and the ratio of the generated carbon dioxide amount to the theoretical amount is shown in FIG. 9 as the degree of biodegradation.

<Example 1>
1 g of water-soluble chitosan having a N-acetylation degree of 50% prepared in Production Example 10 and 1 g of cellulonic acid sodium salt produced in Production Example 2 were dissolved in 100 mL of 0.1N hydrochloric acid solution. Then, 0.2N-NaOH aqueous solution was added and it adjusted to pH7, the gel was produced | generated, and the composite_body | complex of Example 1 was obtained. This complex contained sodium chloride produced by neutralization. This sodium chloride worked as a porous agent for the composite, and the composite was made porous. The composite from which sodium chloride was removed by washing had a sponge-like structure with fine and uniform pores, and showed a feature such as increased water absorption.

<Example 2>
1 g of water-soluble chitosan having a N-acetylation degree of 50% prepared in Production Example 10 and 1 g of amylouronate sodium salt produced in Production Example 1 were dissolved in 100 mL of 0.1N acetic acid solution. Then, 0.2N-NaOH aqueous solution was added and it adjusted to pH 7, and the gel was produced | generated. This composite was dried in an oven at 60 ° C. to obtain a composite of Example 2. This complex includes sodium acetate produced by neutralization.

<Comparative Example 1>
When 100 mL of a 1 wt% aqueous solution of water-soluble chitosan having a N-acetylation degree of 50% prepared in Production Example 10 was mixed with 50 mL of a 2 wt% COOH type aqueous solution of amylouronic acid produced in Production Example 5, a gel was formed. . This complex was dried in an oven at 60 ° C. to obtain a polysaccharide complex of Comparative Example 1.

<Evaluation of Example 2 and Comparative Example 1>
The composite of Example 2 and Comparative Example 1 was immersed in water. Both swollen but did not dissolve. After 1 hour, the tensile elongation of the composite was measured. As a result, Example 2 showed 1.5 to 2 times the elongation of the composite of Comparative Example 1. It was found that the produced sodium acetate improved the elongation of the composite.

  The polysaccharide complex of the present invention can also be obtained by using materials of production examples not used in the above examples and materials not described in the production examples.

Claims (4)

A method for producing a polysaccharide complex comprising at least an oxidized polysaccharide and chitosan,
The oxidized polysaccharide is an oxidized polysaccharide having a carboxyl group or a salt thereof introduced into the 6-position of the pyranose ring of the polysaccharide by oxidation; and
A solution is prepared by dissolving or dispersing the oxidized polysaccharide, the chitosan, and at least one additive selected from a porous agent, a crosslinking agent, a decomposition accelerator, a coupling agent, a bulking agent, and an antibacterial agent. Process,
A step of neutralizing the solution with an acid or an alkali to form a salt for making the polysaccharide complex into a porous structure, and forming a polyion complex of oxidized polysaccharide and chitosan to insolubilize in water A method for producing a polysaccharide complex.   The oxidized polysaccharide is obtained by a method in which a polysaccharide dissolved or dispersed in water is oxidized in an aqueous system using an oxidizing agent in the presence of a catalyst of an N-oxyl compound, and in the pyranose ring of a natural polysaccharide. The method for producing a polysaccharide complex according to claim 1, wherein the primary hydroxyl group at the position is selectively oxidized.   The ratio of glucosamine and N-acetylglucosamine which are the constituent monosaccharides as said chitosan exists in the range of 45:55 to 55:45, The polysaccharide complex of Claim 1 or Claim 2 characterized by the above-mentioned. Production method.   A polysaccharide complex produced by the method for producing a polysaccharide complex according to any one of claims 1 to 3.

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