JPH08134146A - Polymer gel introducing nucleic acid base on side chain and its production - Google Patents

Abstract

PURPOSE: To obtain a polymer gel capable of exhibiting hydration swelling property on high temperature side and dehydration shrinkage on low temperature side, respectively by one kind of gel and favorably utilizing for medicine feeding system for feeding a medicine by the change in temperature by introducing a nucleic acid base onto the side chain. CONSTITUTION: This polymer gel is expressed by formula I [(l) is 10-50; (m) is 90-500; (n) is 1-10] and introduces a nucleic acid base on the side chain. The polymer gel is obtained by reacting, e.g. (A) 6-acryloyloxymethyl uracil of formula II obtained by reacting potassium acrylate with 6-chloromethyluracil with in the presence of 18-crown-6-ether in DMF with (B) acrylic acid or acrylic acid and acrylic amide (C) in a solvent in the presence of (D) a radical initiator and (E) a crosslinking agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel polymer gel exhibiting low-temperature contraction / high-temperature swelling behavior in response to temperature and a method for producing the same, and more particularly to a drug delivery system for delivering a drug by changing temperature.
m) a new polymer gel capable of enabling

[0002]

2. Description of the Related Art A new drug delivery system (pharmaceutical composition) capable of holding a drug in blood at an effective concentration for a long period of time, or a drug product capable of allowing a drug to act at a required position is proposed. drug delivery
It has been noticed and studied as a system).
Then, use of an alkyl-substituted amide gel was considered as a drug used in the drug delivery system that releases the drug in response to temperature. It was reported that polyacrylamide gel was partially hydrolyzed by alkali, which showed the phase inversion phenomenon of gel in water-acetone system, and that alkyl-substituted amide showed extremely large swelling change with temperature change in water. It was thought that it might adapt to use. However, the alkyl-substituted amide gel has a drawback of low mechanical strength.

Therefore, the inventors of the present invention have proposed an intervene network structure (I
Polymers with PN) have been proposed. The IPN means that the crosslinked polymer is composed of two kinds of polymers which are physically entangled with each other instead of covalent bonds in an alternating wet network structure.
As a kind of polymer compound, an alternating wet network polymer structure of the following three-dimensional copolymer of the general formula A and three-dimensional copolymer of the general formula B has been proposed (for example, see JP-A-3-79608). ).

[0004]

Embedded image

However, this polymer structure utilizes an interaction between two types of polymer chains having the roles of a hydrogen-bonding donor and an acceptor, respectively. Dehydration due to complex formation,
It utilizes the hydration-dehydration behavior of an interpolymer complex, which is the hydration of each polymer chain observed with the complex dissociation at a certain temperature or higher.

By the way, the present inventor has various contraction and swelling characteristics of a polymer gel consisting of one kind of polymer chain as an alternative to the behaviors of contraction at low temperature and swelling at high temperature due to the complex between the two kinds of polymers. investigated. Thus, conventionally, a compound having a temperature dependence based on hydration-dehydration behavior by one kind of polymer chain has been used as poly (N-
Isopropyl acrylamide) is known. This compound is hydrated at a low temperature to increase its swelling property, and is rapidly dehydrated at about 32 ° C. to decrease its swelling property.
However, the compounds that can be used in drug delivery systems are rather those that hydrate at high temperature and become more swellable and release the drug, and at low temperature they dehydrate and have less swelling and stop release of the drug. Is preferred.

[0007]

Therefore, the present inventor has
As a result of various studies on polymers having properties of dehydration on the low temperature side and hydration on the high temperature side with only one type of polymer chain, the present invention has been completed, and the present invention shrinks and swells with one type of polymer gel. It is an object of the present invention to provide a novel polymer which exhibits the characteristics described above, hydrates and swells on the high temperature side, and dehydrogenates on the low temperature side.

[0008]

The gist of the present invention is a polymer gel in which a nucleobase is introduced into the side chain represented by the general formula (1).

[0009]

[Chemical 4]

The polymer gel can be obtained by reacting acrylooxymethyluracil and acrylic acid or acrylic acid and acrylic acid amide in a solvent in the presence of a radical initiator and a crosslinking agent. This polymer
The gel is dehydrated at a low temperature in water or in a buffer solution close to physiological conditions, and the temperature is around 40 ° C (about 50% in the buffer solution).
It has the property of hydrating at a high temperature with a boundary of ℃).

Acrylooxymethyluracil, which is a raw material of this polymer gel, is prepared by a known method such as Brahm.
e method and the like (J. Polymer Sc
i. , Polym. Chem. Ed. 22: 813 (1984)). The resulting acrylooxymethyluracil (referred to as AU monomer) is reacted with acrylic acid or acrylic acid and acrylic acid amide in a solvent in the presence of a radical initiator and a cross-linking agent, which may be used at this time. The solvent is dimethyl sulfoxide (DMSO), dimethylformamide (DMF), etc., and the radical initiator is azobisisobutyronitrile (AIB).
N) and N-methylene bis acrylamide etc. can be mentioned as a crosslinking agent.

[0012]

EXAMPLES Next, the method for producing the polymer gel of the present invention will be specifically shown as examples, but the present invention is not limited to these examples. Example 1 (i) Synthesis of acrylic uracil (AU) monomer 10 ml of acrylic acid (6.1 ml, 0.09 mol)
The aqueous solution was neutralized with a 20 ml aqueous solution of KOH (5 g 0.09 mol). 100 ml of benzene was added to the solution whose neutralization was confirmed by pH test paper, and this mixed solution was added to Dea.
Using n-Starkapparatus, refluxed overnight to remove 31 ml of water. The potassium acrylate in the flask is separated by filtration, first 100
It was washed with acetone (50 ml) and then with ether (50 ml) and dried. Obtained potassium acrylate (1.1 g, 0.0
1 mol of 18-crown-6-ether (2.64)
mol, 0.01 mol) and 6-chloromethyluracil (1.1 g, 0.01 mol) were added to 30 ml of a DMF solution. The reaction mixture was refluxed at 100 ° C. for 18 hours, and the solvent DMF was distilled off under reduced pressure to obtain an oily substance. 25 ml to this
Water was added and the mixture was allowed to stand for 2 hours. The separated solid was filtered, washed with ethanol and dried. This reaction formula is shown below.

[0013]

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(Ii) Synthesis of polyacrylic uracil (PAU) AU monomer (1.34 obtained by the above method)
g, 0.0068 mol) of DMF solution was replaced with nitrogen,
Using α, α′-azobisisobutyronitrile (AIBN) as an initiator, polymerization was carried out at 60 ° C. for 48 hours. The solvent DMF was distilled off under reduced pressure, and the resulting oil was diluted with the minimum amount of DM.
It was dissolved in SO (5 ml) and poured into acetone for reprecipitation. The precipitated solid was collected by filtration, reprecipitated twice from acetone in the same way and finally reprecipitated with 95% ethanol and dried. This reaction formula is shown below.

[0015]

[Chemical 6]

The PAU polymer aqueous solution thus obtained was prepared, and its transmittance (Transmittance%) was measured. That is, the obtained PAU was treated with ultrapure water and a phosphate buffer aqueous solution (Phosphate Buffer Salin).
e, PBS (pH 7.4)).
A 0 wt% aqueous polymer solution was prepared. A constant temperature cell was attached to the UV-visible spectrophotometer, the transmittance (T%) of each aqueous solution at a predetermined temperature at 500 nm was measured, and the temperature dependence of this transmittance was investigated. The result is shown in Figure 1.
It was shown to. Aqueous solution of PAU polymer is 45 ℃ in purified water.
It showed low temperature cloudiness / high temperature dissolution. The phosphate buffer solution showed low temperature cloudiness / high temperature dissolution at a temperature of 50 ° C. At low temperature, PAU formed a polymer complex, which was insolubilized and became cloudy, and the transmittance was 0%. At high temperature, however, this polymer complex was dissociated and dissolved, resulting in a high transmittance value. Is considered to indicate. The rapid change in the permeability of the aqueous polymer solution at a certain temperature as the temperature changed indicates that the formation of a polymer complex due to the polymer effect in the PAU molecule
It is considered to be based on dissociation. As the intramolecular interaction at this time, hydrogen bond, hydrophobic interaction, van der Waals force, etc. are considered.

(Iii) Formation of Copolymer Polymer Gel In a sample bottle, acrylamide (AAm), acrylic acid (AAc), dimethylacrylamide (DMAAm),
2,2-Azobis (2-aminodipropane) dihydrochloride (V-50) and N, N-methylenebisacrylamide (MBAAm) were added to the reagents at the ratios shown in Table 1 to obtain PUAc and PUAc-10. , PUAm was obtained.

[0018]

[Table 1]

5 ml of DMS degassed from each of these reagents
A copolymer polymer gel was prepared by dissolving in O. The monomer solution was poured between two glass plates with a Teflon spacer having a thickness of 0.5 mm and a mylar sheet attached, and the mixture was reacted at 60 ° C. for 24 hours. Poly (acryloyloxymesyluracil-acrylic acid) copolymer (P
The reaction formula for UAc) is shown below.

[0020]

[Chemical 7]

After the completion of the reaction, it was immersed in purified water to remove DMSO and unreacted substances. After that, the hydrous gel was punched out into a disk shape with a diameter of 1.3 mm, and the gel was squeezed at 50 ° C for 24 hours.
And dried under reduced pressure at 50 ° C. for 24 hours. The gel of the obtained poly (acryloyloxymesyluracil-acrylic acid) copolymer (PUAc) was measured for swelling degree and change in swelling degree with external change. In other cases, that is, P
The same applies to the cases of UAc-10 and PUAm. a. Swelling degree measurement The dry weight (Wp) of this gel was measured, and this was put in a sample bottle filled with purified water and a phosphate buffer solution (pH 7.4), and the water content (Ws at equilibrium at 10 ° C to 60 ° C) (Ws) was measured. ) Was measured. This Ws was measured after taking out the gel from water and removing excess water with a medicine wrapping paper. b. Measurement of change in swelling degree due to external changes Put the gel in a sample bottle containing purified water, and at low temperature for 1 hour 3
The temperature was raised for 0 minutes and the temperature was raised for 30 minutes at a high temperature. It was determined by measuring the mass of the gel with respect to the temperature change of the degree of swelling of the gel. PU in aqueous solution
The temperature dependence of the equilibrium swelling degree of Ac is shown in FIG. 2, and the temperature dependence of the equilibrium swelling degree in the phosphate buffer solution is shown in FIG.

From these results, the temperature dependence of the low-temperature shrinkage / high-temperature swelling behavior of the PUAc gel in the purified water and the phosphate buffer solution was observed. It is considered that at a low temperature, a uracil-uracil complex is formed and dehydrated to shrink, and at a high temperature, this complex dissociates and hydrates to swell. Although the degree of swelling in the phosphate buffer solution was considerably higher than that in the purified water, the COOH of acrylic acid in the phosphate buffer solution was dissociated by protons, and the swelling degree was high due to the ion repulsion. It is thought to have been shown.

Next, the degree of swelling of the gel of poly (acryloyloxymesyluracil-acrylamide) copolymer (PUAm) and changes in the degree of swelling with external changes were measured. The result is shown in FIG. In this case as well, the temperature dependence of the low-temperature shrinkage / high-temperature swelling behavior was observed in the purified water and the phosphate buffer solution.
m showed a low degree of swelling. This is because PUAc swells due to repulsion of ions due to proton dissociation of acrylic acid, whereas acrylamide swells in phosphate buffer solution (pH 7.
It is considered that the degree of swelling was suppressed because proton dissociation did not occur even in 4).

Next, the copolymer polymer gels at 35 ° C.
And PUA when the external temperature is changed in the range of 40 ℃
The change in the degree of swelling of gels of c and PUAc-10 in purified water was measured. The results are shown in FIGS. 5 and 6. Even when the low temperature and the high temperature were repeated 3 and 4 times, a reversible change in the swelling degree was shown within a certain range. Similar to the equilibrium swelling degree, this change in swelling degree is considered to be a fold and swelling by forming an interuracil complex at low temperature, contracting by dehydration, and dissociating and hydrating at high temperature. Further, when the crosslinking concentration is 1 mol% (P
The swelling degree of 10 mol% (PUAc-10) was considerably lower than that of UAc), and the swelling degree with good reversibility could be obtained even if the crosslinking concentration was increased.

[0025]

As described above, the polymer gel in which the uracil group is introduced exhibits the behavior of low temperature shrinkage and high temperature swelling with one type of polymer chain, and further, it is obtained by copolymerization with AAm.
The UAm gel behaved similarly in the phosphate buffer solution. In addition, the reversibility of the change in the degree of swelling of the gel with the change in temperature was observed, and it was expected that it could be used as a temperature-responsive polymer gel.

[Brief description of drawings]

FIG. 1 Temperature dependence of transmittance of water and phosphate buffer solution in which PAU is dissolved

FIG. 2 Temperature dependence of equilibrium swelling degree of PUAc gel in aqueous solution

FIG. 3 Temperature dependence of equilibrium swelling degree of PUAc gel in phosphate buffer solution

FIG. 4 Temperature dependence of equilibrium swelling degree of PUAm gel in water and phosphate buffer solution

FIG. 5: PUAc with temperature change between 35 and 40 ° C.
Change of swelling degree of gel in water

FIG. 6 PUAc with temperature change between 35 and 40 ° C.
-10 Change in swelling degree of gel in water

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Junko Seki 7-15 Futaba-cho, Itabashi-ku, Tokyo (72) Inventor Mitsuo Okano 6-12-12 Kokufudai, Ichikawa-shi, Chiba (72) Inventor Yasuhisa Sakurai Suginami, Tokyo 3-17-6 Eifu, Ward

Claims (2)

[Claims] 1. A polymer gel in which a nucleic acid base is introduced into the side chain represented by the general formula (1). 1 represents 10 to 50, m represents 90 to 50, and n represents 1 to 10. 2. Acrylooxymethyluracil and acrylic acid or acrylic acid and acrylic acid amide in a solvent,
A method for producing a polymer gel in which a nucleobase is introduced into a side chain represented by the general formula (1), which comprises reacting in the presence of a radical initiator and a crosslinking agent. Embedded image 1 represents 10 to 50, m represents 90 to 50, and n represents 1 to 10.