JP2015209462A - Preparation method of molecular assembly of amphiphilic block polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in a film method, a novel preparation method of a molecular assembly having more uniform particle diameter and a narrow particle size distribution, and to provide, in a film method, a preparation method which can increase an amount of the molecular assembly prepared in one lot.SOLUTION: The preparation method of a molecular assembly containing an amphiphilic polymer comprises, for example: distilling off a solvent from a solution in a vessel, containing a linear or branched amphiphilic block polymer to thereby form a film comprising the block polymer; and thereafter adding water or an aqueous solution into the vessel to prepare a molecular assembly. The solvent is distilled off to form the film in a state where one or more granular bodies are immersed in the solution in the vessel.

Description

  The present invention relates to a novel method for producing fine particles (molecular assemblies) having a nano-level (several tens of nanometers) particle diameter used in the fields of pharmaceuticals, agricultural chemicals, foods, battery materials, and the like. More specifically, the present invention relates to a so-called film method in which a solvent in which an amphiphilic block polymer is dissolved is distilled off in a container to form a film, and then a molecular assembly is prepared by adding water or the like.

Fine particles or molecular assemblies having nano-level particle diameters are applied in various fields. In particular, in the pharmaceutical field, the focus is on the dynamics of nanoparticles in vivo. For example, molecular imaging technology, molecular probes, and drug delivery system (DDS) technology for efficiently delivering drugs to affected areas such as tumor tissues Particles are applied. Specifically, for example, by enclosing the fluorescent agent or ¹⁸ polymer added with the radioisotope, such as ^F, such as indocyanine green (ICG) in such fine particles, attempts have been made to the molecular probe. In addition, attempts have been made to encapsulate drugs such as anticancer agents and photosensitizers in such fine particles, and to efficiently transport and treat the drug to the target lesion.
As the fine particles (molecular aggregates), for example, the following are disclosed.
(1) Hydrophobic polypeptide chain comprising a hydrophilic polypeptide chain having 10 or more sarcosine units, a unit selected from the group consisting of an amino acid unit and a hydroxyl acid unit as an essential constituent unit, and having 5 or more of the essential constituent units A molecular assembly comprising an amphiphilic block polymer having a molecular chain (see Patent Document 1).
(2) an amphiphilic block polymer having a hydrophilic block chain having 20 or more sarcosine units, a hydrophobic block chain having 10 or more lactic acid units, and 10 or more lactic acid units and a labeling group A molecular assembly comprising at least a labeled polymer (see Patent Document 2).
(3) A molecular assembly having a branched amphiphilic block polymer having a branched hydrophilic block containing sarcosine and a hydrophobic block having polylactic acid (see Patent Document 3).
At least the amphiphilic block polymers according to the above (2) and (3) can be self-assembled relatively easily to form polymer micelles having a particle size of about 30 nm, that is, molecular assembly. Moreover, it is also called “Lactosomes” (registered trademark, hereinafter omitted) because of its excellent characteristics.
Examples of a method for producing a molecular assembly such as lactosome include an injection method, a film method, an ultrasonic method, and an extruder method.
Among these, the injection method is a method in which an amphiphilic block polymer is dissolved in an organic solvent such as trifluoroethanol, and the resulting solution is dispersed in an aqueous solvent such as water for injection and purified by gel filtration chromatography or the like. And then removing the organic solvent.
In the film method, in a suitable container, an amphiphilic block polymer is dissolved in an organic solvent such as chloroform, and the organic solvent is distilled off to form a film in the container. In this method, the solvent is added and heated.

JP 2008-24816 A International Publication No. 2009/148121 International Publication No. 2012/176885

According to the film method, a nano-level molecular assembly can be easily produced. In addition, the film method is relatively easy to study conditions, and is suitable for the production of a molecular assembly of a small amount (for example, 10 mg / mL or less). However, in the film method, it may be difficult to produce a molecular assembly having a uniform particle size, that is, a narrow particle size distribution. Moreover, there is a possibility that the amount of molecular assemblies that can be produced in one lot is not sufficient.
From the above situation, the main object of the present invention is to provide a novel production method capable of producing a molecular assembly having a more uniform particle size and a narrow particle size distribution. Another object of the present invention is to provide a production method capable of increasing the amount of molecular assemblies that can be produced in one lot in the film method.

  As a result of intensive studies, the inventors have formed a film by distilling off the solvent in a state where the granular material is immersed in the solution in the container, and then adding water or an aqueous solution to make the particle diameter uniform. As a result, the inventors have found that a large number of nano-level molecular assemblies can be produced, and have completed the present invention.

Examples of the present invention include the following.
[1] A film having the block polymer is formed by distilling off the solvent from the solution containing the linear or branched amphiphilic block polymer in the container, and then water or an aqueous solution in the container. A method for producing a molecular assembly by adding
A method for producing a molecular assembly containing the amphiphilic block polymer (hereinafter referred to as the following), wherein the film is formed by distilling off the solvent in a state where one or more granules are immersed in the solution in the container. , Also referred to as “the manufacturing method of the present invention”).

[2] The method for producing a molecular assembly according to [1], wherein the granular body is a sphere.

[3] The method for producing a molecular assembly according to [2], wherein the sphere is a glass bead.

[4] The method for producing a molecular assembly according to any one of [1] to [3], wherein the total surface area of the granular material is 10 times or more the surface area of the inner wall of the container in contact with the solution.

[5] The molecular assembly according to any one of [1] to [4], wherein the amphiphilic block polymer includes a hydrophilic block chain having a sarcosine unit and a hydrophobic block chain having a lactic acid unit. How to make a body.

[6] The method for producing a molecular assembly according to [5], wherein the hydrophilic block chain has sarcosine units in the range of 2 to 500.

[7] The method for producing a molecular assembly according to the above [5], wherein the hydrophobic block chain has lactic acid units in the range of 5 to 100.

[8] The method for producing a molecular assembly according to any one of [1] to [7], wherein the amphiphilic block polymer has a functional group.
[9] The method for producing a molecular assembly according to any one of [1] to [8], wherein the solution containing the amphiphilic block polymer before film formation contains a functional substance.

[10] The method for producing a molecular assembly according to [8], wherein the functional group is a signal group or a ligand group.

[11] The method for producing a molecular assembly according to [9], wherein the functional substance is a signal agent or a drug.

[12] The method for producing a molecular assembly according to any one of the above [1] to [11], which does not include a filter treatment step for particle size and particle size distribution control.

[13] The method for producing a molecular assembly according to any one of [1] to [12], wherein the concentration of the amphiphilic block polymer in the solution before film formation is greater than 10 mg / mL.

[14] The method for producing a molecular assembly according to any one of [1] to [13], further including a freeze-drying step.

  According to the production method of the present invention, a nano-level molecular assembly having a uniform particle size and a narrow particle size distribution can be produced in a large amount (high concentration) in one lot. Therefore, it is advantageous from the viewpoint of practical use and quality control of pharmaceuticals.

It is a schematic diagram for demonstrating an example of the conventional film method. It is a schematic diagram for demonstrating an example of the manufacturing method of this invention. The measurement result of the particle diameter of the particle | grains obtained in Example 1 is represented. In the figure, the vertical axis represents scattered light intensity (%), and the horizontal axis represents particle diameter (nm). The solid line shows the particle size distribution curve after particle formation, and the broken line shows the particle size distribution curve after 200 nm filter treatment. The measurement result of the particle diameter of the particle | grains obtained in Example 2 is represented. In the figure, the vertical axis represents scattered light intensity (%), and the horizontal axis represents particle diameter (nm). The solid line shows the particle size distribution curve after particle formation, and the broken line shows the particle size distribution curve after 200 nm filter treatment. The measurement result of the particle diameter of the particle | grains obtained in Example 3 is represented. In the figure, the vertical axis represents scattered light intensity (%), and the horizontal axis represents particle diameter (nm). The solid line shows the particle size distribution curve after particle formation, and the broken line shows the particle size distribution curve after 200 nm filter treatment. The measurement result of the particle diameter of the particle | grains obtained in Example 4 is represented. In the figure, the vertical axis represents scattered light intensity (%), and the horizontal axis represents particle diameter (nm). The solid line shows the particle size distribution curve after particle formation, and the broken line shows the particle size distribution curve after 200 nm filter treatment. The measurement result of the particle diameter of the particle | grains obtained by the comparative example 1 is represented. In the figure, the vertical axis represents scattered light intensity (%), and the horizontal axis represents particle diameter (nm). A solid line indicates a particle size distribution curve after particle formation, a rough broken line (-) indicates a particle size distribution curve after 200 nm filter treatment, and a fine broken line (---) indicates a particle size distribution curve after 100 nm filter treatment.

  Hereinafter, the production method of the present invention will be described in detail.

  The production method of the present invention is to form a film having the block polymer by distilling off the solvent from the solution containing the linear or branched amphiphilic block polymer in the container, and then into the container. A method for producing a molecular assembly by adding water or an aqueous solution, wherein the film is formed by distilling off the solvent in a state where one or more granular bodies are immersed in the solution in the container. This is a method for producing a molecular assembly containing the amphiphilic block polymer.

I. About Granules The gist of the production method of the present invention is to distill off the solvent in a state in which one or more granules are immersed in the solution in the container.

  The granular body includes a step of forming a film having the block polymer by distilling off the solvent from the solution containing the linear or branched amphiphilic block polymer in the container, and water in the container. Alternatively, there is no particular limitation as long as the step of preparing a molecular assembly by adding an aqueous solution smoothly proceeds, and examples thereof include a sphere, an ellipsoid, a cylinder, and a polyhedron. Among them, a sphere is preferable because a film having a uniform thickness can be formed, and thereby a molecular assembly having a more uniform particle diameter can be formed.

The material of the granular material is inactive in the step of forming a film having an amphiphilic block polymer and the step of preparing a molecular assembly in the container, and the polymer film can be formed on the surface of the granular material. Any material can be used without particular limitation, and examples thereof include glass, resin, metal, rubber, and ceramic.
Specific examples of the granular material include glass beads, metal beads, and ceramic beads.

In carrying out the production method of the present invention, one or more granular materials may be used, and the number is not particularly limited, but usually a plurality is used. The number of granules used depends on the size and shape of the granules, the capacity and shape of the container, and the like.
The total surface area of the one or more granular materials is not particularly limited, but is preferably 10 times or more, more preferably 20 times or more, the surface area of the inner wall of the container in contact with the solution. When the total surface area of the granular material is less than 10 times the surface area of the inner wall of the container with which the solution is in contact, there is a possibility that only a molecular assembly having the same amount as that of the conventional film method without the granular material can be produced.

  Furthermore, by using one or more granules, the surface area on which a film having an amphiphilic block polymer is formed can be increased, and a uniform thin film can be formed. The polymer solution becomes more uniform. In addition, when water or an aqueous solution is added to the container to produce a molecular assembly, the granular material on which the film is formed is physically rubbed with the inner wall of the container or between the granular materials, thereby forming particles. The effect of being performed smoothly can also be obtained.

  The size of the granule may be appropriately adjusted depending on the capacity of the container, the size of the mouth, etc. For example, in the case of a sphere such as glass beads, the diameter is usually 1 to 20 mm, preferably 2 to 10 mm. is there. When the size of the granular material is within the above range, after the molecular assembly is prepared, an operation for collecting the granular material from the container can be easily performed.

II. About a solution containing a linear or branched amphiphilic block polymer Next, a linear or branched amphiphilic block polymer (hereinafter, these are also simply referred to as “amphiphilic block polymer”). The containing solution will be described in detail.

  The amphiphilic block polymer is not particularly limited as long as it can form a molecular assembly by a film method. For example, it includes a hydrophilic block chain having a sarcosine unit and a hydrophobic block chain having a lactic acid unit. Is preferred.

  The sarcosine unit of the hydrophilic block chain differs depending on whether it is linear or branched, and whether it has a constituent unit other than the sarcosine unit, etc., but the entire block chain (copolymer molecule) is hydrophilic and such a copolymer. There is no particular limitation as long as the molecule is hydrophilic to such an extent that the molecule can self-assemble in a solvent to form a molecular assembly, and is usually in the range of 2 to 500, and 20 if it is linear. The range of about ˜500 is appropriate, preferably about 40 to 300, and more preferably about 50 to 100. In the case of a branched type, the total of sarcosine units contained in all branches is suitably in the range of about 2 to 600, preferably about 10 to 400, and more preferably about 50 to 300.

  The hydrophilic block chain is preferably a polypeptide chain having a sarcosine unit. In the polypeptide chain, the sarcosine units may be continuous or discontinuous.

  The hydrophilic block chain may have a structural unit other than the sarcosine unit. Examples of the structural unit other than the sarcosine unit include natural amino acids, unnatural amino acids, and derivatives thereof. More specifically, examples include serine, threonine, lysine, aspartic acid, and glutamic acid.

  The lactic acid unit of the hydrophobic block chain differs depending on whether it is linear or branched, or whether it has a structural unit other than the lactic acid unit, etc., but the entire block chain (copolymer molecule) is hydrophobic, and such a copolymer There is no particular limitation as long as the molecule is hydrophobic enough to self-assemble in a solvent to form a molecular assembly, and is usually in the range of 5 to 100, preferably about 10 to 80. More preferably, it is about 20 to 60 pieces.

  The lactic acid unit may be composed of only the L-lactic acid unit, may be composed of only the D-lactic acid unit, or may be composed of both the L-lactic acid unit and the D-lactic acid unit. When the lactic acid unit is composed of both the L-lactic acid unit and the D-lactic acid unit, the polymerization order of the L-lactic acid unit and the D-lactic acid unit is not particularly limited, and the L-lactic acid unit, the D-lactic acid unit, May be alternately polymerized one by one or two at a time, may be polymerized randomly, or may be block polymerized. When a lactic acid unit is comprised from both an L-lactic acid unit and a D-lactic acid unit, content of each lactic acid unit is not specifically limited.

  The hydrophobic block chain may have a structural unit other than the lactic acid unit. Examples of the structural unit other than lactic acid include hydroxyl acids and amino acids other than lactic acid, and more specifically, hydroxyl acids such as glycolic acid and hydroxyisobutyric acid; glycine, alanine, valine, leucine, and isoleucine. And natural amino acids such as proline, methionine, tyrosine and tryptophan; and non-natural amino acids such as glutamic acid methyl ester, glutamic acid benzyl ester, aspartic acid methyl ester, aspartic acid ethyl ester and aspartic acid benzyl ester.

  When the amphiphilic block polymer is a branched amphiphilic block polymer, only the hydrophilic block chain may have a branched structure, or only the hydrophobic block chain may have a branched structure, Both the hydrophilic block chain and the hydrophobic block chain may have a branched structure.

  In addition, the amphiphilic block polymer may be a linear amphiphilic block polymer alone or a branched amphiphilic block polymer alone. Mixtures of block polymers may be used.

  The amphiphilic block polymer may have other groups. Other groups may be appropriately selected by those skilled in the art according to the use of the molecular assembly produced by the production method of the present invention. Examples of such other groups include functional groups such as organic groups (described later).

  The solvent for dissolving the amphiphilic block polymer is not particularly limited as long as it is inert to form an amphiphilic block polymer film, but the boiling point at 1 atm is 100 ° C. or less, preferably 90 ° C. The following low-boiling solvents are preferably used. Examples of such solvents include chloroform, diethyl ether, acetonitrile, methanol, ethanol, propanol, butanol acetone, dichloromethane, tetrahydrofuran, hexane and the like.

  The concentration of the amphiphilic block polymer in the solution varies depending on the type of the solvent and the amphiphilic block polymer, and is not particularly limited as long as it is appropriately adjusted depending on the type, shape, size, number, etc. of the particles and granules. Thus, it is possible to obtain a high density which is difficult with the conventional film method. Examples of such concentrations include 10 mg / mL to saturated dissolution concentration or less, 50 mg / mL to saturation dissolution concentration or less, and 100 mg / mL to saturation dissolution concentration or less. Thereby, compared with the conventional film method, a molecular assembly can be produced in large quantities.

  The solution in which the amphiphilic block polymer is dissolved may contain optional components such as a functional substance (described later) and additives.

  Examples of the additive include polylactic acid for controlling particle diameter, an additive for improving stability, an antioxidant and the like.

  The polylactic acid is not particularly limited as long as the particle diameter can be controlled, and a D-form, an L-form having a mean molecular weight of 1000 to 50000, preferably 2000 to 10000, or a mixture thereof is appropriately used depending on the purpose. Commercially available polylactic acid can be used as it is. The addition amount of the polylactic acid may be appropriately adjusted depending on the type of amphiphilic block polymer, the target particle size, etc., but is usually 0.1 mol% to 1000 mol% with respect to the amphiphilic polymer, preferably Is 10 mol% to 200 mol%.

  Examples of the additive for improving stability include a hydrophobic additive. Of these, aliphatic esters are preferred. The addition amount of the additive may be appropriately adjusted depending on the type of amphiphilic block polymer, the type of additive, and the like. However, in order not to affect the particle diameter, the amount is usually 10 mol% with respect to the amphiphilic polymer. Hereinafter, it is preferably 5 mol% or less. There is no limit if the effect on particle size is not considered.

  Examples of the antioxidant include tocopherol, its ester, ascorbic acid, butylhydroxytoluene, butylhydroxyanisole, propyl gallate and the like. Of these, tocopherol is preferred. The addition amount of the antioxidant may be appropriately adjusted depending on the type of the amphiphilic block polymer, the type of the antioxidant, etc. Usually, in order not to affect the particle size, It is 10 mol% or less, preferably 5 mol% or less. There is no limit if the effect on particle size is not considered.

III. Step of Forming Film Having Amphiphilic Block Polymer Subsequently, the film having the block polymer is formed in the container by evaporating the solvent from the solution containing the amphiphilic block polymer in the container. The process will be described in detail.

  As a container for forming a film, a person skilled in the art may appropriately select the type of amphiphilic block polymer and solvent, the type and shape of granules, the size, the number, the method of distilling off the solvent, and the like. Glass containers are suitable, and specific examples include glass eggplant-shaped flasks, round bottom flasks, cylindrical containers and the like. Also, the size of the container can be appropriately selected by those skilled in the art depending on the amount of the amphiphilic block polymer and the solvent, the type, shape, size, number and the like of the granular material.

  The method for distilling off the solvent may be appropriately selected by those skilled in the art depending on the type of amphiphilic block polymer and solvent, etc., and may be removed under reduced pressure. Removal may be performed. Among these, when removing the solvent under reduced pressure, it is preferable to use an evaporator because the operation is simple and the solvent can be removed in a short time. By distilling off the solvent in this manner, a film having an amphiphilic block polymer is formed on the surface of the granular body in addition to the inner wall surface of the container.

When removing the solvent under reduced pressure using an evaporator, the reduced pressure condition may be appropriately adjusted according to the size of the container, the type of the solvent, and the like, but usually in a hot water bath at 25 ° C. to 60 ° C. for 5 minutes to 60 minutes. Just a minute.
Moreover, you may vacuum-dry as needed.

  The thickness of the film containing the amphiphilic block polymer formed varies depending on the concentration of the amphiphilic block polymer in the solution, etc., and depends on the capacity of the container and the type, shape, size, number, etc. of the granular materials. The trader may adjust as appropriate, but in order to produce a molecular assembly having a more uniform particle size, water or water is used between the film formed on the inner wall surface of the container and the film formed on the surface of the granular material. The thickness is preferably such that there is a gap enough to contain the aqueous solution.

IV. Step of producing a molecular assembly by adding water or an aqueous solution into a container Subsequently, a step of producing a molecular assembly by adding water or an aqueous solution into a container will be described in detail.

  As described above, when the solvent is distilled off from the solution containing the amphiphilic block polymer in a suitable container, a film having the amphiphilic block polymer is formed on the inner wall surface of the container and the surface of the granular material in the container. . Water or an aqueous solution is added to the container in which this film is formed, and an amphiphilic block polymer or the like is dispersed or self-assembled to produce a molecular assembly.

  The water or aqueous solution to be added is not particularly limited as long as it is an aqueous medium in which a molecular assembly is formed, and may be appropriately selected according to the application. Specific examples include purified water, distilled water, and ultrapure water. When preparing a molecular assembly for use in medicine, a person skilled in the art may appropriately select a biochemically and pharmaceutically acceptable one. Such water or aqueous solution may be, for example, water for injection, physiological Examples include saline, buffer solution, and other general infusions.

The amount of the water or the aqueous solution is not particularly limited, and may be added to the extent that all the amphiphilic block polymers in the container can form a molecular assembly.
Specifically, the concentration of the amphiphilic block polymer in the obtained dispersion of the molecular assembly varies depending on the use of the molecular assembly to be obtained. For example, when used as an injection as it is, 1 mg / mL When freeze-dried by lyophilization at about 10 mg / mL, about 20 mg / mL to 100 mg / mL can be mentioned. According to the production method of the present invention, a molecular assembly having a high concentration can be obtained as compared with the conventional film method.

After adding water or aqueous solution, a heating process can be performed as needed. A molecular assembly is formed in the process in which the film having the amphiphilic block polymer is peeled off from the inner wall surface of the container and the surface of the granular material by heating.
The heating treatment may be appropriately adjusted according to the thickness of the film having the amphiphilic block polymer, the size of the container, the amount of the granular material, and the like, but usually in the range of 60 ° C to 100 ° C for 5 minutes to 60 ° C. Can be done for a minute.

  Ultrasonic treatment or manual or mechanical shaking may be performed simultaneously with the heating treatment or after the heating treatment as necessary. Moreover, you may perform the filter process for particle diameter and particle size distribution control after a heating process as needed. Filter processing for particle size and particle size distribution control is performed in order to obtain a uniform molecular aggregate with a uniform particle size distribution, excluding unnecessary excessive particles. According to the production method of the present invention, the particle size and particle size distribution are controlled. A molecular assembly with a narrow uniform particle size distribution that does not contain unnecessary excessive particles can be obtained without performing filtering for control or a small number of times.

  If necessary, after the heating process, a filter process for removing dust or the like in the sterilization or manufacturing process may be performed simultaneously with or after the filter process for controlling the particle size or the particle size distribution. Filter processing for removing dust and the like in the sterilization and manufacturing process can be performed by a conventional method, and may be performed by the same method as the filter processing for particle size and particle size distribution control, or by a different method. May be.

  After adding water or an aqueous solution to the container, the obtained dispersion liquid of the molecular assembly can be used as it is without performing the lyophilization treatment described below.

V. About freeze-drying process The production method of the present invention may further include a freeze-drying process.

  The freeze-drying step can be performed by a conventional method. For example, it can be carried out by freezing the obtained dispersion liquid of the molecular assembly with liquid nitrogen or the like and sublimating it under reduced pressure. More specifically, if necessary, after sterilizing the obtained dispersion liquid of the molecular assembly, a predetermined amount is dispensed into a suitable container such as a vial, and the condition is about −40 ° C. to −20 ° C. Pre-freezing is performed for about 2 hours, primary drying is performed at about 0 ° C. to 10 ° C. under reduced pressure, and then secondary drying is performed at about 15 ° C. to 25 ° C. under reduced pressure for freeze drying. In general, the inside of a container such as a vial can be replaced with nitrogen gas and stoppered to obtain a lyophilized composition of a molecular assembly produced by the production method of the present invention.

  In general, the obtained lyophilized composition can be redissolved and used by adding any appropriate solution (re-dissolution solution). Examples of such redissolved solution include water for injection, physiological saline, buffer solution, and other general infusion solutions. The amount of the re-dissolved solution is not particularly limited and varies depending on applications.

VI. Molecular Assembly Produced by the Production Method of the Present Invention A molecular assembly produced by the production method of the present invention (hereinafter also simply referred to as “molecular assembly”) will be described in detail.

By the production method of the present invention, a micelle-shaped molecular assembly configured such that the inner side (core portion) is a hydrophobic block chain and the outer side (shell portion) is a hydrophilic block chain can be produced. Such a molecular assembly can be provided with a functional structure having a form or function that is useful when used in a molecular imaging system or a drug delivery system (DDS). Thus, the molecular assembly becomes a useful structure as a flow in molecular imaging or as a carrier in a drug delivery system.
In order to prepare a molecular assembly having a functional structure, for example, an amphiphilic block polymer itself having a functional group bonded thereto may be used, and an amphiphilic block polymer before film formation is included. A solution containing a functional substance may be used.

  Examples of the functional group include a signal group and a ligand group.

  The signal group is a group having a characteristic that enables imaging by detection, and examples thereof include a fluorescent group, a radioactive element-containing group, and a magnetic group. Examples of the fluorescent group include groups derived from ICG, Cy7, DY776, DY750, Alexa790, Alexa750, rhodamine, quantum dots, and the like. Among them, a group derived from ICG, Cy7, DY776, DY750, Alexa790, and Alexa750 is preferable because it is possible to provide useful information when a measurement target is specified as a small animal or a site close to the body surface.

Examples of the radioactive element-containing group include groups derived from sugars, amino acids, nucleic acids, peptides, synthetic polymers and the like labeled with radioactive isotopes such as ¹⁸ F and ¹¹¹ In.

  Examples of the magnetic group include those having a magnetic material such as ferrichrome and ferrocene.

  A ligand group is a group that controls the directivity of a molecular assembly by binding to a biomolecule expressed in a target cell, thereby increasing the targeting property of the molecular assembly. Peptides and sugar chains can be mentioned.

Examples of the antibody include those having a specific binding ability to an antigen expressed in a cell at a target site.
Examples of cell adhesion peptides include adhesion factors such as RGD (arginine-glycine-aspartic acid).
Examples of sugar chains include stabilizers such as strength ruboxylmethylcellulose and amylose, and those having specific binding ability to proteins expressed in cells at the target site.

  The bonding position of the functional group is not particularly limited. For example, functional groups can be exposed on the surface (shell part) of the molecular assembly produced by binding to the terminal structural unit of the hydrophilic block chain of the amphiphilic block polymer. The functional group can be included in the core portion of the produced molecular assembly by binding to the terminal structural unit of the hydrophobic block chain.

  A functional substance is included by being located in the hydrophobic core part of the molecular assembly produced. Examples of such a functional substance include a signal agent and a drug.

As a signal agent, the compound which has the above-mentioned signal group can be mentioned, for example. Among them, containing near-infrared fluorescent substances such as fluorescein dyes and cyanine dyes, and radioactive elements such as sugars, amino acids, nucleic acids, peptides, proteins and synthetic polymers labeled with radioactive isotopes such as ¹⁸ F and ¹¹¹ In Substances are preferred.
A drug suitable for the target disease is appropriately selected by those skilled in the art. Specific examples include anticancer agents, antibacterial agents, antiviral agents, anti-inflammatory agents, immunosuppressive agents, steroid agents, hormone agents, angiogenesis inhibitors and the like. These drug molecules can be used alone or in combination of two or more kinds.

  The functional substance may have a polylactic acid group bonded thereto. The polylactic acid group is a group having a lactic acid unit as a main constituent. All of the lactic acid units may be continuous or discontinuous. Basically, the structure, chain length, and optical purity of the polylactic acid group can be determined from the same viewpoint as in the molecular design of the hydrophobic block described above. By doing in this way, in a molecular assembly, the effect that it is excellent in affinity with a functional substance and the hydrophobic block of an amphiphilic block polymer is also acquired.

  The number of lactic acid units in the polylactic acid group is usually in the range of 15 to 60, preferably about 25 to 45. Within this range, the molecular design is such that the total length of the polylactic acid-binding functional substance does not exceed the length of the above-mentioned amphiphilic block polymer. Preferably, the molecular design is such that it does not exceed twice the length of the hydrophobic block in the amphiphilic block polymer. When the number of structural units exceeds the above range, when the molecular assembly is formed, the formed molecular assembly tends to lack stability. When the number of structural units is below the above range, the affinity between the functional substance and the hydrophobic block of the amphiphilic block polymer tends to be weakened.

  The optical activity of the polylactic acid chain in the polylactic acid-binding functional substance is preferably the same as that of the branched amphiphilic block polymer or linear amphiphilic block polymer that is a constituent element of the molecular assembly. For example, when the polylactic acid chain in the branched amphiphilic block polymer or the linear amphiphilic block polymer is composed of L-lactic acid units, the polylactic acid chain in the polylactic acid-binding functional substance is also composed of L-lactic acid units. It is preferable.

  The content of the functional substance in the solution containing the amphiphilic block polymer is not particularly limited. For example, in the case of a fluorescent substance, the amount of the fluorescent dye relative to the total of the amphiphilic block polymer and the fluorescent dye. An amount in the range of 0.5 to 50 mol% is appropriate.

  The number average particle diameter of the molecular assembly, which is measured by a dynamic light scattering (DLS), is usually 10 nm to 200 nm, or 20 nm to 50 nm. When the average particle size is smaller than 10 nm, measurement by DLS may be difficult.

In addition, according to the production method of the present invention, even without performing 200 nm to 100 nm filter processing or the like, or by reducing the number of times of processing (specifically, only once), it is uniform without containing excessive particles. A molecular assembly having a narrow particle size distribution can be produced. Specifically, for example, a molecular assembly having a polydispersity index (PDI: PolyDispersity Index) of 0.2 or less can be produced.
Here, the polydispersity index (PDI) is PDI = (D ₉₀ −D ₁₀ ) / D ₅₀ (where D ₉₀ , D ₅₀ , and D ₁₀ are distribution functions G = ∫f (D) dD ( G represents a particle diameter in which the integration of the number of particles and D is the particle diameter is equal to 0.9 (90 number%), 0.5 (50 number%) and 0.1 (10 number%) of the total number of particles. . ] Is obtained from the following formula. That is, in the above relational expression, as the particle size distribution is narrower, the PDI approaches zero, and conversely, the wider the particle size distribution, that is, the greater the polydispersity, the larger the PDI.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Each physical property was measured as follows.
[Particle size]
The produced particles were diluted to 1 mg / mL with distilled water and measured as a number average using a particle size measuring apparatus (Metavern Zetasizer Nano S) by dynamic light scattering (DLS).
[PDI]
It calculated based on the following formula | equation using the measured particle diameter.
PDI = (D ₉₀ -D ₁₀ ) / D ₅₀
(Where D ₉₀ , D ₅₀ , and D ₁₀ are the integrals of the distribution function G = ∫f (D) dD (G is the number of particles, D is the particle size), respectively, and the total number of particles is 0.9 (90 %), 0.5 (50 number%) and 0.1 (10 number%).
[Unimodal]
Whether or not the particle dispersion is unimodal was evaluated using the following indicators.
○: When the particle size distribution curve of the particle size measurement result by the dynamic light scattering method (DLS) is judged to be apparently one peak ×: The particle size distribution curve of the particle size measurement result by the dynamic light scattering method (DLS) is apparent When judged to be above 2 mountains

The raw materials used are as follows.
[Amphiphilic block polymer]
As an amphiphilic block polymer, a polymer in which 66 sarcosine units in the hydrophilic block chain (average value) and 31 lactic acid units in the hydrophobic block chain (average value) are combined (hereinafter referred to as “PSar66-PLLA31”). Used).

Example 1
1 g of PSar66-PLLA31 was dissolved in 10 mL of chloroform (100 mg / mL) in an eggplant flask, and in the presence of 40 g of glass beads (diameter 2.5 to 3.5 mm), using an evaporator, The polymer film was produced on the inner wall surface of the eggplant flask and the glass bead surface under reduced pressure for a minute. Furthermore, after vacuum-drying overnight at room temperature, 20 mL of distilled water was added, and the mixture was heated at 85 ° C. for 30 minutes to form particles (50 mg / mL). After particle formation, the solution was allowed to cool to room temperature, and the particle size was measured. Then, 200 nm filter processing was performed and the particle diameter measurement was performed. The results are shown in Table 1.
Moreover, the graph of a particle diameter measurement result is shown in FIG.

Example 2
Particles were produced in the same manner as in Example 1 except that 20 g of glass beads (diameter 2.5 to 3.5 mm) were used, and the particle diameter was measured. Then, 200 nm filter processing was performed and the particle diameter measurement was performed. The results are shown in Table 1.
Moreover, the graph of a particle diameter measurement result is shown in FIG.

Example 3
Particles were produced in the same manner as in Example 1 except that 40 g of glass beads (diameter: 9.0 to 11.0 mm) were used, and particle formation measurement was performed. Then, 200 nm filter processing was performed and the particle diameter measurement was performed. The results are shown in Table 1.
Moreover, the graph of a particle diameter measurement result is shown in FIG.

Example 4
Particles were prepared in the same manner as in Example 1 except that 40 mL of distilled water was added to form particles (25 mg / mL), and the particle diameter was measured. Then, 200 nm filter processing was performed and the particle diameter measurement was performed. The results are shown in Table 1.
Moreover, the graph of a particle diameter measurement result is shown in FIG.

Comparative Example 1
A polymer film was prepared and granulated under the same conditions as in Example 1 except that glass beads were not placed in the eggplant flask, and the particle size was measured. Then, 200 nm filter processing was performed and the particle diameter measurement was performed. Thereafter, 100 nm filter treatment was performed, and the particle size was measured. The results are shown in Table 1.
Moreover, the graph of a particle diameter measurement result is shown in FIG.

  From the results of Examples 1 to 4 and Comparative Example 1, according to the production method of the present invention, a molecular assembly having a PDI smaller than that of the conventional film method can be obtained without filtering or by reducing the number of times of filtering. It is clear that a molecular assembly with uniform dispersibility can be produced in large quantities in one lot. On the other hand, in the conventional film method, when the filter treatment is not performed, or when only the filter treatment of 200 nm is performed, it is not possible to obtain monomodal particles with a PDI of 0.2 or less.

According to the production method of the present invention, a molecular assembly having a more uniform particle size and a narrow particle size distribution can be produced in a large amount in one lot. Therefore, the present invention provides a molecular imaging system, a drug delivery system (DDS), etc. It is useful in the field of Similarly, it is also useful as a method for producing a substance transport carrier in the fields of cosmetics, food, household goods and the like.

Claims (14)

In the container, the solvent is distilled off from the solution containing the linear or branched amphiphilic block polymer to form a film having the block polymer, and then water or an aqueous solution is added to the container. A method for producing a molecular assembly comprising:
A method for producing a molecular assembly containing the amphiphilic block polymer, wherein the film is formed by distilling off a solvent in a state where one or more granular materials are immersed in a solution in the container. The method for producing a molecular assembly according to claim 1, wherein the granular material is a sphere. The method for producing a molecular assembly according to claim 2, wherein the sphere is a glass bead. The method for producing a molecular assembly according to any one of claims 1 to 3, wherein the total surface area of the granular material is 10 times or more the surface area of the inner wall of the container in contact with the solution. The method for producing a molecular assembly according to any one of claims 1 to 4, wherein the amphiphilic block polymer comprises a hydrophilic block chain having a sarcosine unit and a hydrophobic block chain having a lactic acid unit. 6. The method for producing a molecular assembly according to claim 5, wherein the sarcosine unit of the hydrophilic block chain is in the range of 2 to 500. The method for producing a molecular assembly according to claim 5, wherein the number of lactic acid units in the hydrophobic block chain is in the range of 5 to 100. The method for producing a molecular assembly according to any one of claims 1 to 7, wherein the amphiphilic block polymer has a functional group. The method for producing a molecular assembly according to any one of claims 1 to 8, wherein the solution containing the amphiphilic block polymer before film formation contains a functional substance. The method for producing a molecular assembly according to claim 8, wherein the functional group is a signal group or a ligand group. The method for producing a molecular assembly according to claim 9, wherein the functional substance is a signal agent or a drug. The method for producing a molecular assembly according to any one of claims 1 to 11, which does not include a filter treatment step for particle size and particle size distribution control. The method for producing a molecular assembly according to any one of claims 1 to 12, wherein the concentration of the amphiphilic block polymer in the solution before film formation is 10 mg / mL or more. The method for producing a molecular assembly according to any one of claims 1 to 13, further comprising a freeze-drying step.