JPH058049B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capsule body using a soluble chitin derivative such as chitosan as a film forming material and a method for producing the same.

Conventional technology Conventionally, as a method for manufacturing capsule bodies, a mixture of a polyvalent metal salt such as a calcium salt added to a fluid (core liquid) constituting the core of the capsule body is mixed with alginate, low methoxyl pectin, or the like. A method of forming a gel film by contacting with a solution of a mixture of (Japanese Patent Publication No. 48-16183), an aqueous solution containing a de-N-acetylated product of carboxylmethyl chitin or a carboxylmethyl chitin salt,
A method for manufacturing capsule bodies by dropping, stirring, and dispersing an organic acid in an aqueous anhydride solution such as a mixture of acetic anhydride and acetic acid (Japanese Patent Application Laid-open No. 55-90503)
etc. are known. However, in these known methods, the ionic strength of the liquid (core liquid) constituting the core of the capsule body is high, and the hydrogen ion concentration of the liquid changes rapidly during the capsule formation process.
It is difficult to encapsulate under biologically mild conditions, and therefore it is not suitable as a method for manufacturing capsule bodies for encapsulating biologically unstable substances.

Problems to be Solved by the Invention In the process of researching the formation of a gel film suitable for manufacturing capsule bodies, the present inventor discovered that a solution of chitosan, a type of chitin derivative, and polyphosphoric acid,
The present invention was accomplished based on the finding that an excellent gel film is formed under biologically mild conditions when a solution of metaphosphoric acid, pyrophosphoric acid, or a salt thereof is brought into contact with the material.

That is, an object of the present invention is to provide a gel body that can be formed under biologically mild conditions and a method for producing the gel body. Other objects of the invention will become apparent from the description below.

The present invention will be explained in detail below.

Structure of the Invention The capsule body according to the present invention is characterized by being formed by contacting a fluid based on polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid or a salt thereof or a mixture thereof with a solution of a soluble chitin derivative. The reason is that the above-mentioned fluid is encapsulated in the gel film as a core.

In addition, a feature of the production method according to the present invention is that the fluid constituting the core of the capsule body, which is a solution containing polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, or a salt thereof, alone or in a mixture thereof, is replaced with a soluble chitin derivative. The objective is to form a gel film containing the above-mentioned fluid as a core by dropping the fluid into a solution and contacting it under biologically mild conditions.

Means for Solving the Problems In the present invention, polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, or a salt thereof used to form the gel film of the capsule body is a compound or a salt thereof that becomes a polyanionic polymer in an aqueous solution. , sodium metaphosphate, sodium tripolyphosphate,
Examples include sodium pyrophosphate. These phosphoric acid compounds can be used alone or as a mixture.

On the other hand, the soluble chitin derivatives used to form the same gel film are obtained by chemically treating chitin, which is originally an inert substance, to increase its reaction activity, and are obtained by deacetylating chitin. Chitosan can be exemplified as a typical example.

Incidentally, chitin is N- contained in the carapace of crabs, krill, insects, etc., the cell walls of microorganisms, mushrooms, etc.
It is a linear homopolysaccharide with β (1→4) bonds of acetyl-D-glucosamine, and is produced in abundance in nature, but due to its inactivity it can be said to be an unused natural resource that cannot be used as is. .

However, chitin derivatives such as chitosan obtained by deacetylating chitin become soluble in dilute acids and have reactive activity. That is,
Chitosan has a structural unit represented by the following general formula (), It is positively charged due to the amino group in the formula, has chitosan molecules as a polycationic polymer, and exhibits reactive activity.

Therefore, when a chitosan solution of the soluble chitin derivative as described above is brought into contact with an aqueous solution of the phosphoric acid compound, its salt, or a mixture thereof, a crosslinking reaction due to charge occurs between the phosphoric acid compound and chitosan. to produce a gel-like substance.

In order to bring the two solutions into contact in the present invention, the aqueous solution containing the phosphoric acid compound or its salt may be dropped into the chitosan solution with stirring using a depositor or the like, and at this time the crosslinking reaction occurs. Once a gel film is formed by this crosslinking reaction, the solution encapsulated in the film and constituting the core will not gel at all, making it possible to obtain the desired capsule. This phenomenon occurs because when a gel film is formed, the polyanionic polymer and chitosan molecules in the solution (i.e., core liquid) contained in the gel film can no longer permeate through the film, and the reaction occurs in the core liquid. This is thought to be due to the fact that it stops progressing inside.

In the present invention, the above-mentioned phosphoric acid compound, its salt, or a mixture thereof is used in preparing the solution used as the fluid constituting the core of the capsule body.
It is appropriate to use an aqueous solution containing 0.2% by weight or more, and it is particularly preferable to use sodium metaphosphate as the phosphoric acid compound from the viewpoint of forming a gel film.

The chitosan solution with which the above aqueous solution is brought into contact is suitably one dissolved in a weak acid such as acetic acid to a concentration of 0.5 to 1.0% by weight.

As mentioned above, in the present invention, the gel film of the capsule body can be formed in a short period of time under extremely mild conditions, that is, biologically mild conditions, without using organic solvents. Biological substances, functional substances, and other various additives depending on the purpose of use of the capsule can be added and dispersed in the fluid that constitutes the core of the capsule, so that various useful substances can be added. It becomes possible to provide a capsule body containing in the core liquid.

Examples of things that can be included in the core liquid include animal cells and plant cells dispersed in a culture solution. When such biological substances or functional substances are contained in the core liquid, a decrease in the activity can be prevented.

In addition, the present invention enables encapsulation by forming a gel film in one step.
It can be said that this method is advantageous in terms of production compared to the known encapsulation method that utilizes salt crosslinking between a polyanion and a polycation as seen in No. 197031.

Furthermore, in the present invention, by controlling the formation conditions of the gel film of the capsule body, it is possible to change the membrane permeability of the gel film, so it is also possible to impart a fractionation function to the film of the capsule body. Become.

As described above, the present invention has the advantage of being able to provide a capsule body that can be used in a wide range of applications by using easily available raw materials, by simple manufacturing means, and in a short period of time.

EXAMPLES AND EFFECTS OF THE INVENTION The present invention will be explained in more detail with reference to Examples below.

Example 1 Chitosan was added to an aqueous solution containing 0.1 mol/acetic acid and 0.1 mol/sodium acetate to give a concentration of 0.7% by weight.
A chitosan aqueous solution was prepared. A separately prepared 1% by weight aqueous solution of sodium tripolyphosphate was dripped under pressure into this chitosan aqueous solution with stirring at a temperature of 25° C. through a syringe needle with an inner diameter of 0.4 mm.

A spherical capsule with a diameter of 2 to 3 mm was formed within 2 to 3 minutes after the two solutions came into contact with each other by this dropping. The membrane of the obtained capsule body was white, and even when the capsule body was left in water for a long time, the core liquid contained therein showed stable fluidity and no change was observed.

Example 2 A separately prepared 1% by weight was added to a chitosan aqueous solution prepared in the same manner as in Example 1 at a temperature of 25°C.
An aqueous solution of sodium metaphosphate was added dropwise in the same manner as in Example 1 to form spherical capsules with a diameter of 2 to 3 mm.

The membrane of the obtained capsule body was white and was found to have considerably high strength. Furthermore, even if the capsule body was left in water for a long time, the core contained therein maintained stable fluidity.

Claims (1)

[Scope of Claims] 1. A gel film formed by contacting a fluid based on polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid or a salt thereof or a mixture thereof with a solution of a soluble chitin derivative, A capsule body containing the above-mentioned fluid as a core. 2. Drop the fluid constituting the core of the capsule body, which is an aqueous solution containing polyphosphoric acid, metaphosphoric acid, pyrophosphoric acid, or a salt thereof or a mixture thereof, into a solution of a soluble chitin derivative to make it biologically mild. A method for producing a capsule body, which comprises contacting the fluid under suitable conditions to form a gel film, and encapsulating the fluid as a core.