JP2014156555A - Method for producing nanoparticle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing nanoparticles composed of an amphiphilic block polymer with a uniform particle diameter.SOLUTION: In a method for producing nanoparticles composed of an amphiphilic block polymer having a hydrophilic block and a hydrophobic block, a laminar flow of a polymer solution is formed by introducing a solution including the amphiphilic block polymer having the hydrophilic block and the hydrophobic block in an organic solvent into a polymer solution supply channel, at least two laminar flows of a water-based liquid are formed by introducing the water-based liquid into at least two water-based liquid supply channels, and the nanoparticles composed of the amphiphilic block polymer are formed by merging the laminar flow of the polymer solution with the two laminar flows of the water-based liquid such that the laminar flow of the polymer solution is sandwiched between the mentioned at least two laminar flows of the water-based liquid.

Description

  The present invention belongs to the fields of supramolecular chemistry, medical and pharmaceutical collaboration, and nanomedicine. The present invention relates to a method for producing nanoparticles composed of an amphiphilic block polymer, and more particularly to a method for producing nanoparticles composed of an amphiphilic block polymer using a novel merging structure of a polymer solution and an aqueous liquid. In particular, the present invention is suitable for continuous production of nanoparticles having a uniform particle size made of an amphiphilic block polymer excellent in biocompatibility. The present invention also relates to a microflow cell that can be used for continuous production of the nanoparticles.

  Molecular imaging techniques have been developed to diagnose tumors and other diseases. Examples of molecular imaging techniques include positron tomography PET (Positron Emission Tomography), single photon emission tomography SPECT (Single Photon Emission Computed Tomography), magnetic resonance imaging MRI (Magnetic Resonance Imaging), and fluorescence imaging. . There is a need for a probe that is suitable for each of these diagnoses, has high sensitivity, that is, high accumulation selectivity to a lesion site, and has minimal invasiveness.

  Further, when looking toward the treatment, chemotherapy using an anticancer agent is performed in cancer treatment for metastasis prevention after early treatment and after surgical treatment or radiation treatment. Anticancer drugs have a significant effect on normal tissues and have side effects. Various drug delivery systems (DDS) have been researched and developed to reduce side effects. As one of these, the development of DDS anticancer agents using nanoparticles as a carrier utilizing the characteristics of new blood vessels (EPR effect: Enhanced Permeability and Retention Effect) that are prominently seen during the initial growth of cancer has attracted attention. Nanoparticles have been studied. The EPR effect is a fast-growing tumor in which nanoparticles with a particle size of several tens to several hundreds of nm (for example, about 20 to 200 nm) administered into blood leak from the capillary system with abnormally enhanced permeability. It is a phenomenon in which lymphatic vessels are still underdeveloped in the interstitial space of tissues, helping to accumulate.

  JP-A-11-335267, JP-A-2003-26812 and JP-A-2001-226294 disclose methods for producing polymer micelles containing a poorly water-soluble drug. According to JP 2001-226294 A, an organic solution is prepared by dissolving a poorly water-soluble drug and a block copolymer comprising a hydrophilic segment and a hydrophobic segment in a water-immiscible organic solvent. The obtained organic solution is mixed with an aqueous medium to form an oil-in-water (O / W) type emulsion, and the organic solvent is evaporated from the obtained emulsion to form a polymer micelle solution encapsulating the drug. In addition, a method for producing a polymer micelle in which a poorly water-soluble drug is encapsulated by sonication and ultrafiltration treatment of the obtained polymer micelle solution is disclosed. However, according to the publication, the organic solvent is removed by dialysis, and then the particles are refined by performing ultrasonic treatment (so-called top-down method), and the process is complicated. In addition, when particles are refined by ultrasonic treatment, it is difficult to precisely control the particle size. Furthermore, since the particles once produced by ultrasonic treatment are destroyed and the drug contained in the particles may leak, it is difficult to control the amount of the drug contained.

  Japanese Patent Application Laid-Open No. 2012-213747 discloses a flow channel member having a micro flow channel having a diameter of 50 to 300 μm, and a pressurizing unit that pressurizes a raw material liquid in which particles are dispersed or dissolved and pressurizes the raw material liquid. In addition, a fine particle manufacturing apparatus including a vacuum drying chamber for introducing and drying the raw material liquid that has passed through the flow path member is disclosed. The fine particle production apparatus disclosed in the publication discloses a method of so-called top-down method in which particles that have already been formed are pumped and refined.

  Japanese Patent Application Laid-Open No. 2005-246227 discloses a method for producing bubble-containing leuco dye-encapsulated microcapsules that can be broken by ultrasonic waves or pressure. The particle size of the produced microcapsule is as large as a micrometer size (for example, 4 μm [0021] in the first embodiment and 6 μm [0033] in the third embodiment). Since a homogenizer is used to refine a large particle size to a micrometer size (so-called top-down method), it is difficult to control the amount of leuco dye contained in the microcapsule.

  In JP 2009-256324 A, a volatile organic acid aqueous solution containing a physiologically active substance or a volatile organic acid solution of a physiologically active substance is mixed with a volatile organic solvent containing a biodegradable polymer to produce an emulsion. And a method for producing bioactive substance-containing microparticles comprising a step of mixing the obtained emulsion with an aqueous solution of a negatively charged polymer. There is no description regarding the particle size of the fine particles.

  JP 2012-170861 A discloses at least two inlets I1 to In (n ≧ 2), at least one outlet O, inlet channels C1 to Cn connected to the inlets I1 to In, respectively, With respect to the flow channel structure X having the flow channel portion J formed by joining the inlet flow channels C1 to Cn simultaneously or stepwise, the raw material of the hydrogel from the inlet I1 A gelling agent solution G is continuously introduced from the inlet I2 to form a fiber in which the sol solution Z is at least partially gelled in the flow path portion J; Non-spherical hydrogel by cutting the fiber by confining the fiber in which the sol solution Z is at least partially gelled in the droplet inside or outside the X Making children, synthesis of non-spherical hydrogel particles is disclosed. According to the publication, the sol solution Z is continuously introduced together with the gelling agent solution G to form a fiber in which the sol solution Z is gelled in the flow path portion J after the merge. The fiber formed by the gelation is confined in the droplet to cut the fiber to produce non-spherical hydrogel particles. The publication does not disclose an amphiphilic block polymer, and the produced hydrogel particles have a very large diameter of about several μm to several centimeters ([0021]).

  As nanoparticles used in a drug delivery system (DDS), for example, JP 2008-24816 A (US Patent Application Publication US 2008/0019908) discloses an amphiphilic block polymer having a hydrophilic block and a hydrophobic block. The hydrophilic block is a hydrophilic polypeptide chain having 10 or more sarcosine units, and the hydrophobic block includes a unit selected from the group consisting of an amino acid unit and a hydroxyl acid unit as an essential constituent unit. In addition, an amphiphilic block polymer that is a hydrophobic molecular chain having 5 or more of the essential structural units is disclosed, and a molecular assembly having a particle size of 10 to 500 nm composed of the amphiphilic block polymer is disclosed.

  International Publication WO 2009/148121 and Biomaterials, 2009, Vol. 30, p. No. 5156-5160 is a polymer micelle having a linear amphiphilic block polymer in which a hydrophobic block is a polylactic acid chain and a hydrophilic block is a polysarcosine chain is self-assembled in an aqueous solution and has a particle size of 30 nm or more. Forming (lactosomes). In addition to high blood retention, lactosomes have been shown to significantly reduce the amount of accumulation in the liver as compared to polymeric micelles that have been developed so far. This lactosome is a molecular imaging that targets cancerous sites by utilizing the property (EPR effect) that nanoparticles with a particle size of several tens to several hundreds of nanometers staying in the blood easily collect in cancerous diseases. Alternatively, it can be applied as a nanocarrier for drug delivery.

  International publication WO2012 / 17685 discloses that a branched amphiphilic block polymer having a branched hydrophilic block containing sarcosine and a hydrophobic block having polylactic acid is self-assembled in an aqueous solution and has a particle size of 10 It is disclosed to form ˜50 nm polymeric micelles (lactosomes).

JP 11-335267 A JP 2003-26812 A JP 2001-226294 A JP 2012-213747 A JP 2005-246227 A JP 2009-256324 A JP 2012-170861 A JP 2008-24816 A US Patent Application Publication US2008 / 0019908 WO2009 / 148121 WO2012 / 176885 gazette

Biomaterials, 2009, volume 30, p. 5156-5160

  In the above-mentioned WO2009 / 148121 and WO2012 / 176885, nanoparticles are produced from an amphiphilic block polymer by a film method. The film method includes the following steps. That is, a step of preparing a solution containing an amphiphilic block polymer in an organic solvent in a container (for example, a glass container), removing the organic solvent from the solution, and containing the amphiphilic block polymer on the inner wall of the container A step of obtaining a film, and a step of adding water or an aqueous solution to the container and performing ultrasonic treatment to convert the film-like substance into a particle-like molecular aggregate to obtain a dispersion liquid of the molecular aggregate. Furthermore, the film method may include a step of subjecting the dispersion of the molecular assembly to a lyophilization treatment. The film method is a batch method, which is not preferable from the viewpoint of productivity, and is not suitable for controlling the particle size between batches.

  Moreover, although what was actually performed is not disclosed in the above-mentioned WO2009 / 148121 and WO2012 / 1768585, it is also disclosed that nanoparticles are produced by an injection method (WO2009 / 148121). [0145] of WO2012 / 176885, [0088]). The injection method includes the following steps. That is, a step of preparing a solution containing an amphiphilic block polymer in an organic solvent in a container (for example, a test tube), a step of dispersing the solution in water or an aqueous solution, and a step of removing the organic solvent Done. Further, in the injection method, a purification treatment step may be appropriately performed before the step of removing the organic solvent. The disclosed injection method is a batch type, is not preferable from the viewpoint of productivity, and is not suitable for controlling the particle size between batches.

  On the other hand, in order to obtain a desired EPR effect, it is desired to produce nanoparticles having a uniform particle diameter in the range of, for example, about 20 to 200 nm.

  An object of the present invention is to provide a method for producing nanoparticles comprising an amphiphilic block polymer having a uniform particle size.

  As a result of intensive studies, the inventors of the present invention formed a laminar flow of an amphiphilic block polymer solution having a hydrophilic block and a hydrophobic block and a laminar flow of at least two aqueous liquids. Are formed so that the laminar flow is sandwiched between the laminar flows of the at least two aqueous liquids to continuously form nanoparticles composed of an amphiphilic block polymer having a uniform particle size in the range of about 20 to 200 nm. The present inventors have found that this can be done and have completed the present invention.

The present invention includes the following inventions.
(1) A method for producing nanoparticles comprising an amphiphilic block polymer having a hydrophilic block and a hydrophobic block,
A solution containing an amphiphilic block polymer having a hydrophilic block and a hydrophobic block in an organic solvent is introduced into the polymer solution supply channel to form a laminar flow of the polymer solution,
Introducing an aqueous liquid into at least two aqueous liquid supply channels to form a laminar flow of at least two aqueous liquids;
The method for producing nanoparticles, wherein the laminar flow of the polymer solution is merged so as to be sandwiched between the laminar flows of the at least two aqueous liquids to form nanoparticles composed of an amphiphilic block polymer.

(2) a polymer solution inlet;
The polymer solution supply channel connected to the polymer solution inlet;
At least two aqueous liquid inlets;
The at least two aqueous liquid supply channels respectively connected to the aqueous liquid inlet;
A merge part where the polymer solution supply channel and the at least two aqueous liquid supply channels merge;
A nanoparticle formation channel located downstream of the confluence, and
A nanoparticle-containing liquid outlet at the downstream end of the nanoparticle formation channel;
Have
The merging portion uses a micro flow cell formed by arranging the at least two aqueous liquid supply channels so as to sandwich the polymer solution supply channel,
Introducing the amphiphilic block polymer-containing solution from the polymer solution inlet, supplying a laminar flow of the polymer solution to the junction through the polymer solution supply channel,
An aqueous liquid is introduced from the at least two aqueous liquid inlets, and a laminar flow of the at least two aqueous liquids is supplied to the junction through the at least two aqueous liquid supply channels.
While the laminar flow of the polymer solution and the laminar flow of the aqueous liquid are brought into contact with each other toward the downstream side of the nanoparticle formation flow path from the confluence, nanoparticles formed of an amphiphilic block polymer are formed,
The method for producing nanoparticles according to claim 1, wherein a liquid containing the formed nanoparticles is obtained from the nanoparticle-containing liquid outlet.

(3) The micro flow cell is
A substrate,
A resin film disposed on the substrate and formed with the polymer solution supply channel, the at least two aqueous liquid supply channels, the junction, and the nanoparticle formation channel;
The polymer solution inlet is formed at a position corresponding to the upstream end of the polymer solution supply flow path disposed on the resin film, and at least at a position corresponding to the upstream end of each of the at least two aqueous liquid supply flow paths. Two aqueous liquid inlets are formed, a cover sheet in which the nanoparticle-containing liquid outlet is formed at a position corresponding to the downstream end of the nanoparticle formation flow path,
Have
The method for producing nanoparticles according to (2), wherein the substrate, the resin film, and the resin film and the cover sheet are bonded in a liquid-tight state.

(4) The merging portion of the microflow cell is configured such that a laminar flow of the aqueous liquid is generated at the downstream end of the polymer solution supply channel from the left and right sides with respect to the flow direction of the polymer solution from upstream to downstream. The method for producing nanoparticles according to (2) or (3) above, wherein the two aqueous liquid supply channels are arranged with respect to the polymer solution supply channel so as to sandwich the laminar flow of .

(5) The said amphiphilic block polymer has a hydrophilic block having an alkylene oxide unit and / or a sarcosine unit and a hydrophobic block having a hydroxy acid unit, in any one of the above (1) to (4) The manufacturing method of the nanoparticle of description.

(6) The method for producing nanoparticles according to any one of (1) to (5), wherein the amphiphilic block polymer has a hydrophilic block having a sarcosine unit and a hydrophobic block having a lactic acid unit. .

(7) The method for producing nanoparticles according to (6), wherein the total number of sarcosine units contained in the hydrophilic block is 2 to 300.

(8) The method for producing nanoparticles according to (6) or (7), wherein the number of lactic acid units contained in the hydrophobic block is 5 to 400.

(9) The method for producing nanoparticles according to any one of (1) to (8), wherein the formed nanoparticles have a particle size of 10 to 200 nm.

(10) The method for producing nanoparticles according to any one of (1) to (9) above, wherein the particle size distribution of the formed nanoparticles exhibits unimodality.

(11) The nanoparticle according to any one of (1) to (10), wherein a drug and / or a labeling agent is contained in the polymer solution to obtain a nanoparticle containing the drug and / or the labeling agent. Production method.

(12) The nanoparticle according to any one of (1) to (11), wherein a drug and / or a labeling agent is contained in the aqueous liquid to obtain a nanoparticle containing the drug and / or the labeling agent. Manufacturing method.

(13) A microflow cell for producing nanoparticles composed of an amphiphilic block polymer having a hydrophilic block and a hydrophobic block,
At least one polymer solution inlet;
At least one polymer solution supply channel connected to the polymer solution inlet;
At least two aqueous liquid inlets;
At least two aqueous liquid supply channels respectively connected to the aqueous liquid inlets;
A merge part where the polymer solution supply channel and the at least two aqueous liquid supply channels merge;
A nanoparticle formation channel located downstream of the confluence, and
A nanoparticle-containing liquid outlet at the downstream end of the nanoparticle formation channel;
Have
The junction part is a micro flow cell in which the at least two aqueous liquid supply channels are arranged so as to sandwich the polymer solution supply channel.

The micro flow cell is
A substrate,
A resin film disposed on the substrate and formed with the polymer solution supply channel, the at least two aqueous liquid supply channels, the junction, and the nanoparticle formation channel;
The polymer solution inlet is formed at a position corresponding to the upstream end of the polymer solution supply flow path disposed on the resin film, and at least at a position corresponding to the upstream end of each of the at least two aqueous liquid supply flow paths. Two aqueous liquid inlets are formed, a cover sheet in which the nanoparticle-containing liquid outlet is formed at a position corresponding to the downstream end of the nanoparticle formation flow path,
Have
The substrate, the resin film, and the resin film and the cover sheet are bonded to each other in a liquid-tight state.

The confluence portion of the microflow cell is configured such that the flow of the aqueous liquid flows from the left and right sides of the flow direction of the polymer solution from the upstream to the downstream at the downstream end of the polymer solution supply flow path. The microflow cell for producing the above-mentioned nanoparticles, wherein the two aqueous liquid supply channels are arranged with respect to the polymer solution supply channel so as to be sandwiched.

A method for controlling the particle size of nanoparticles composed of an amphiphilic block polymer having a hydrophilic block and a hydrophobic block,
A solution containing an amphiphilic block polymer having a hydrophilic block and a hydrophobic block in an organic solvent is introduced into the polymer solution supply channel to form a laminar flow of the polymer solution,
Introducing an aqueous liquid into at least two aqueous liquid supply channels to form a laminar flow of at least two aqueous liquids;
A method for controlling the particle size of nanoparticles, wherein the laminar flow of the polymer solution is merged so as to be sandwiched between the laminar flows of the at least two aqueous liquids to form nanoparticles made of an amphiphilic block polymer having a uniform particle size .

  In the present invention, a laminar flow of an amphiphilic block polymer solution having a hydrophilic block and a hydrophobic block and a laminar flow of at least two aqueous liquids are formed, and the laminar flow of the polymer solution includes the at least two laminar flows. Nanoparticles made of an amphiphilic block polymer are formed by merging them so as to be sandwiched between laminar flows of an aqueous liquid.

  In the joining portion (that is, the downstream end of the polymer solution supply flow path), the laminar flow of the aqueous liquid causes the laminar flow of the polymer solution from the left and right sides, for example, with respect to the flow direction of the polymer solution from upstream to downstream. Pinch. Then, the laminar flow of the polymer solution flows through the center of the flow channel from the confluence portion to the nanoparticle formation flow channel (upstream portion of the nanoparticle formation flow channel), and the laminar flow of the aqueous liquid flows around the flow channel. It flows through the part (the part in contact with the inner wall of the flow path). The laminar flow velocity of the polymer solution is accelerated by flowing through the center of the flow path, and the area of the liquid-liquid interface with the laminar flow of the aqueous liquid surrounding the flow increases. The self-assembly of the amphiphilic block polymer is considered to occur mainly at the liquid-liquid interface. By increasing the area of the liquid-liquid interface at the junction and increasing the flow velocity of the polymer solution laminar flow, the self-assembly of the amphiphilic block polymer is promoted and has a uniform particle size in the range of about 20 to 200 nm (ie, Nanoparticles are formed (the particle size distribution is unimodal).

  Since the nanoparticles made of the amphiphilic block polymer produced in the present invention have a uniform particle diameter in the range of about 20 to 200 nm, a desired EPR effect can be obtained. Therefore, when the nanoparticle contains a labeling agent, it becomes a useful molecular probe in a molecular imaging system. Furthermore, when a drug is contained in the nanoparticles, it becomes a useful carrier in a drug delivery system (DDS).

  Furthermore, according to the present invention, nanoparticles composed of an amphiphilic block polymer can be continuously produced. Continuous production is excellent in production efficiency, and stably gives uniform-sized nanoparticles without variation in particle size between batches.

  Furthermore, according to the present invention, the particle size of the nanoparticles can be controlled by changing the flow velocity of the laminar flow of the amphiphilic block polymer solution and the laminar flow of the aqueous liquid.

FIG. 1 is a plan view schematically showing the confluence of a laminar flow of a polymer solution and a laminar flow of an aqueous liquid in the present invention. FIG. 2 is a schematic configuration diagram illustrating an example of a nanoparticle production apparatus. FIG. 3 is a diagram showing details of the microflow cell. 4 (a), (b), and (c) are graphs showing the DLS measurement results in Example 1, and FIG. 4 (d) is a diagram showing an outline of the flow path of the used microflow cell. 5 (a), (b), and (c) are graphs showing the DLS measurement results in Comparative Example 1, and FIG. 5 (d) is a diagram showing an outline of the flow path of the used microflow cell. FIG. 6 is a plan view schematically showing the merge of the laminar flow of the polymer solution and the laminar flow of the aqueous liquid in the comparative example. FIGS. 7A, 7B, and 7C are graphs showing the DLS measurement results in Example 2, and FIG. 7D is a diagram showing an outline of the flow path of the used microflow cell. 8A, 8B, and 8C are graphs showing the DLS measurement results in Comparative Example 2, and FIG. 8D is a diagram showing an outline of the flow path of the used microflow cell. FIG. 9 is a diagram basically showing the same simulation as that shown in FIG. 1 with respect to the simulation of the flow path merging structure shown in FIG. ) Is a graph showing a simulation result. FIG. 10 is basically the same as that shown in FIG. 6 with respect to the simulation of the merged structure of the Y-shaped channel shown in FIG. FIG. 10B is a graph showing a simulation result.

[1. Amphiphilic block polymer]
In the present invention, the amphiphilic block polymer has a hydrophilic block and a hydrophobic block, and is particularly capable of forming nanoparticles by self-organization by contact with an aqueous liquid (water or aqueous solution). It can be used without limitation. A nanoparticle is a particle having a nano-order size, and includes molecular aggregates such as micelles and vesicles.

  For example, an amphiphilic block polymer having a hydrophilic block having an alkylene oxide unit and / or a sarcosine unit and a hydrophobic block having a hydroxy acid unit can be used. Examples of the alkylene oxide unit include an ethylene oxide unit and a propylene oxide unit. In the case of ethylene oxide units, the hydrophilic block will contain PEG chains. Examples of the hydroxy acid unit include glycolic acid, lactic acid, and hydroxybutyric acid.

  Hereinafter, an amphiphilic block polymer having a hydrophilic block having a sarcosine unit and a hydrophobic block having a lactic acid unit will be described as an example of the amphiphilic block polymer. The amphiphilic block polymer may be either linear or branched. The hydrophilic block and the hydrophobic block are bonded via a linker portion.

[1-1. Hydrophilic block]
In the present invention, the specific level of the physical property “hydrophilic” possessed by the hydrophilic block of the amphiphilic block polymer is not particularly limited, but at least the entire hydrophilic block is hydrophobic as described below. The property which is relatively hydrophilic with respect to the polylactic acid chain as a functional block. Or hydrophilic property of the grade which becomes possible to implement | achieve amphiphilic property as a whole copolymer molecule, when a hydrophilic block forms a copolymer with a hydrophobic block. In addition, the hydrophilicity is such that the amphiphilic block polymer can self-assemble in a solvent to form a self-assembly, particularly a particulate self-assembly.

  In the present invention, the amphiphilic block polymer may have a linear structure or a branched structure in the hydrophilic block. In the case of the branched structure, each branch of the hydrophilic block contains sarcosine.

  In the hydrophilic block, the types and ratios of the structural units are appropriately determined by those skilled in the art so that the entire block is hydrophilic as described above. For example, the total number of sarcosine units contained in the hydrophilic block is 2 to 300. Specifically, in the case of a linear type, the total of sarcosine units may be, for example, about 10 to 300, 20 to 200, or about 20 to 100. When the number of structural units exceeds the above range, when the molecular assembly is formed, the formed molecular assembly tends to lack stability. Below the above range, an amphiphilic block polymer is not formed, or formation of a molecular assembly tends to be difficult.

  In the case of the branched type, the total number of sarcosine units contained in all branches may be, for example, 2 to 200, 2 to 100, or 2 to 10. Or the sum total of the sarcosine unit contained in all the some hydrophilic blocks may be 30-200 or 50-100, for example. The average number of sarcosine units per branch can be, for example, 1-60, 1-30, 1-10, or 1-6. That is, each hydrophilic block can be configured to include a sarcosine or polysarcosine chain. When the number of structural units exceeds the above range, when the molecular assembly is formed, the formed molecular assembly tends to lack stability. Below the above range, an amphiphilic block polymer is not formed, or formation of a molecular assembly tends to be difficult.

  In the case of the branched type, the number of branches in the hydrophilic block may be 2 or more, but is preferably 3 or more from the viewpoint of efficiently obtaining particle-shaped micelles when forming a molecular assembly. The upper limit of the number of branches in the hydrophilic block is not particularly limited, but is 27, for example. In particular, in the present invention, the number of branches of the hydrophilic block is preferably 3. The branch structure can be appropriately designed by those skilled in the art.

Sarcosine (i.e. N- methyl glycine) has high water-solubility, also polymers of sarcosine cis than ordinary amide group because of their N-substituted amide - are possible trans isomerization, addition, C ^alpha carbon around Since there is little steric hindrance, it has high flexibility. The use of such a structure as a building block is very useful in that the block has basic characteristics with high hydrophilicity or basic characteristics having both high hydrophilicity and high flexibility.

  Furthermore, it is preferable that the hydrophilic block has a hydrophilic group (for example, represented by a hydroxyl group) at the terminal (that is, the terminal opposite to the linker part).

  In the polysarcosine chain, all sarcosine units may be continuous or non-consecutive, but the molecular design was made so as not to impair the basic characteristics of the polypeptide chain as a whole. It is preferable.

[1-2. Hydrophobic block]
In the present invention, the specific degree of the physical property of “hydrophobic” possessed by the hydrophobic block is not particularly limited, but at least the hydrophobic block is relative to the entire hydrophilic block. In other words, it is a region having a strong hydrophobicity, and it is sufficient if the copolymer molecule is formed so as to be amphiphilic as a whole by forming a copolymer with the hydrophilic block. Alternatively, it is sufficient that the amphiphilic block polymer is hydrophobic enough to allow self-assembly in a solvent to form a self-assembly, preferably a particulate self-assembly.

  The hydrophobic block present in one amphiphilic block polymer may not be branched or may be branched. However, when the hydrophobic block is not branched, the density of the hydrophilic branched shell portion increases with respect to the hydrophobic core portion, so that a stable core / shell molecular assembly having a smaller particle size is formed. It is thought that it is easy to do.

  In the present invention, the hydrophobic block includes a polylactic acid chain (PLA). The types and ratios of the structural units in the hydrophobic block are appropriately determined by those skilled in the art so that the entire block is hydrophobic as described above. For example, the number of lactic acid units contained in the hydrophobic block is 5 to 400. Specifically, for example, when the hydrophobic block is not branched, the number of lactic acid units may be, for example, 5 to 100, 15 to 60, or 25 to 45. When the hydrophobic block is branched, the total number of lactic acid units contained in all branches may be, for example, 10 to 400, preferably 20 to 200. In this case, the average number of lactic acid units per branch is, for example, 5 to 100, preferably 10 to 100.

  When the number of structural units exceeds the above range, when a molecular assembly is formed, the formed molecular assembly tends to lack stability. If the number of structural units is less than the above range, formation of the molecular assembly tends to be difficult.

  When the hydrophobic block is branched, the number of branches is not particularly limited, but from the viewpoint of efficiently obtaining particle-shaped micelles when forming a molecular assembly, for example, the number of branches in the hydrophilic block may be less than or equal to it can.

Polylactic acid has the following basic characteristics.
Polylactic acid has excellent biocompatibility and stability. For this reason, a molecular assembly obtained from an amphiphilic substance having polylactic acid as a building block is very useful in terms of applicability to a living body, particularly a human body.
In addition, polylactic acid has an excellent biodegradability, so it is rapidly metabolized and has low accumulation in tissues other than cancer tissues in vivo. For this reason, a molecular assembly obtained from an amphiphilic substance having polylactic acid as a building block is very useful in terms of specific accumulation in cancer tissue.
Since polylactic acid is excellent in solubility in a low-boiling solvent, when a molecular assembly is obtained from an amphiphilic substance having such a polylactic acid as a building block, a harmful high-boiling solvent is used. It is possible to avoid use. For this reason, such a molecular assembly is very useful in terms of safety to living bodies.

  In the polylactic acid chain (PLA) constituting the hydrophobic block, all lactic acid units may be continuous or discontinuous. However, the hydrophobic block as a whole has the above basic characteristics. It is preferable that the molecule is designed so as not to be damaged.

  The polylactic acid chain (PLA) constituting the hydrophobic block is a poly L-lactic acid chain (PLLA) composed of L-lactic acid units or a poly D-lactic acid chain composed of D-lactic acid units ( PDLA). Moreover, you may be comprised from both the L-lactic acid unit and the D-lactic acid unit. In this case, the L-lactic acid unit and the D-lactic acid unit may be any of an alternating arrangement, a block arrangement, or a random arrangement.

[1-3. Ratio of sarcosine units to lactic acid units]
In the amphiphilic block polymer, the number of sarcosine units (that is, the number of sarcosine units contained in the hydrophilic block, or the total number of sarcosine units contained in all branches when the hydrophilic block is branched) and N ^S, polylactic acid unit number (i.e., the number of lactic acid units contained in the hydrophobic block, or the total number of lactic acid units contained in all branches in the case where the hydrophobic block is branched) and N ^L The ratio N ^S / N ^L can then be, for example, 0.05-5 or 0.05-4. More ^preferably, N S / ^{N L} is 0.05 or more and less than 1.8, for example 0.05 to 1.7, 0.05 or 1.67 or less, 0.1 to 1.7, or 0 1 or more and 1.67 or less.

[1-4. Polymer structure]
The structure of the linker moiety that connects the hydrophilic block and the hydrophobic block is not particularly limited as long as it is a chemically acceptable structure. Those skilled in the art can appropriately design the molecule.

  In the case of a branched structure, for example, when the number of branches on the hydrophilic block side is 2, two molecules containing a polysarcosine chain from one N atom at the linker site of the molecular chain containing a polylactic acid chain Chains can be branched. In other words, the N atom directly or indirectly bound to the polylactic acid chain can be directly or indirectly bound to the two polysarcosine chains.

  For example, when the number of branches on the hydrophilic block side is 3, three molecular chains including a polysarcosine chain are branched from one C atom in the linker site of the molecular chain including a polylactic acid chain. sell. In other words, the C atom directly or indirectly bonded to the polylactic acid chain can be directly or indirectly bonded to the three polysarcosine chains. The same applies to the case where one P atom or Si atom in the linker site is branched, or when the entire amphiphilic block polymer molecule forms a quaternary ammonium molecule.

  When the number of branches on the hydrophilic block side exceeds 3, the molecule can be designed so that the branches have a further branched structure.

  In the case where the hydrophobic block side is also branched, the molecular design can be performed from the same viewpoint as described above.

  The following formula (I) shows a preferred structure of the branched amphiphilic block polymer in which the number of branches on the hydrophilic block side is 3 and there is no branch on the hydrophobic block side.

  In the formula (I), n1, n2 and n3 are numbers that are 3 to 200 in total, m is a number of 5 to 100, and R is a hydrogen atom or an organic group. The organic group may have 1 to 20 carbon atoms. Specific examples include an alkyl group and an alkylcarbonyl group.

  The following formula (II) shows a preferred structure of the branched amphiphilic block polymer when the number of branches on the hydrophilic block side is 3 and the number of branches on the hydrophobic block side is 2.

  In formula (II), n1, n2 and n3, and R are the same as in formula (I). m1 and m2 represent the numbers whose total is 10-400.

[1-5. Synthesis method of amphiphilic block polymer]
A person skilled in the art can appropriately synthesize a linear amphiphilic block polymer. For example, a hydrophobic block part (polylactic acid part) is synthesized and a functional group (for example, an amino group) that can serve as a linker for connecting a hydrophilic block part (polysarcosine part) is introduced to one end of a polylactic acid chain. . Next, polysarcosine may be introduced into this amino group.

  In the synthesis of a branched amphiphilic block polymer, the synthesis of a hydrophobic block part (polylactic acid part), the synthesis of a hydrophilic block part (sarcosine part or polysarcosine part), and the synthesis of a linker part connecting these blocks Made.

  For example, a linker reagent for linking a sarcosine or polysarcosine chain and a polylactic acid chain is synthesized, and is used as an initiator to extend by addition of a sarcosine moiety or by a polymerization reaction of a polysarcosine moiety and a polymerization reaction of a polylactic acid moiety. Thus, a branched amphiphilic block polymer can be synthesized.

  Further, for example, after adding sarcosine to a linker reagent, or by preparing a polysarcosine chain as a hydrophilic block in advance by a polymerization reaction and adding it to a linker reagent, the polylactic acid chain is elongated to thereby extend branched parents. A solvable block polymer can be synthesized.

  Furthermore, for example, both polysarcosine or both polysarcosine chain and polylactic acid chain are prepared in advance as a hydrophilic block and a hydrophobic block, respectively, and these blocks are linked using a separately synthesized linker reagent, thereby branching type. Amphiphilic block polymers can be synthesized.

  The linker reagent has one functional group (for example, a hydroxyl group, an amino group, etc.) that can bind to a lactic acid monomer (lactic acid or lactide) or a polylactic acid chain, or a number corresponding to the desired number of branches on the hydrophobic block side. In addition, a functional group (for example, an amino group) capable of binding to a sarcosine monomer (for example, sarcosine or N-carboxy sarcosine anhydride) or polysarcosine can be provided in a number corresponding to the desired number of branching on the hydrophilic block side. In this case, in the linker reagent, molecular design is appropriately performed by those skilled in the art so that each functional group capable of binding to the sarcosine monomer or polysarcosine has the same reactivity as much as possible.

  The functional group capable of binding to the lactic acid monomer or polylactic acid chain and the functional group capable of binding to the sarcosine monomer or polysarcosine can be protected by a protecting group, respectively. In this case, as each protecting group, those capable of being selectively removed as necessary are appropriately selected by those skilled in the art. For example, a linker reagent for synthesizing a branched amphiphilic block polymer having 3 hydrophilic branch side branching numbers can be prepared based on, for example, a trishydroxymethylaminomethane (Tris) structure.

  Furthermore, when the hydrophobic block side is branched, for example, it can be prepared based on a structure in which branch points are further increased to the above-described trishydroxymethylaminomethane structure. The structure with an increased branching point is all of trishydroxymethylaminomethane, amino acids having amino groups in the side chain as specific functional groups capable of binding to polylactic acid chains (specific examples include lysine and ornithine). By adding an amino acid derivative in which the amino group is protected, followed by deprotection. A branch point can be increased by adding a similar amino acid derivative to the amino group which has been deprotected and freed.

A method for synthesizing the polysarcosine chain and the polylactic acid chain can be appropriately determined by those skilled in the art depending on the functional group in the linker reagent, and may be selected from known peptide synthesis methods and polyester synthesis methods.
Peptide synthesis is preferably performed, for example, by ring-opening polymerization of N-carboxysarcosine anhydride (sarcosine NCA) using a basic group such as an amino group in a linker reagent as an initiator.
The polyester synthesis is preferably performed, for example, by ring-opening polymerization of lactide using a basic group such as an amino group in a linker reagent as an initiator.

  In addition, when synthesizing a branched amphiphilic block polymer having a different number of branches from the above specific examples, those skilled in the art can appropriately prepare various modifications from the viewpoint of organic chemistry.

The chain lengths of the polysarcosine chain and the polylactic acid chain can be adjusted by adjusting the charge ratio between the initiator and the monomer in the polymerization reaction. The chain length can be confirmed by, for example, ¹ HNMR.

[2. Molecular assembly]
In the present invention, molecular aggregates such as micelles, multiple micelles, and vesicles having a size of nano order by aggregation of amphiphilic block polymers having hydrophilic blocks and hydrophobic blocks or by self-assembled orientation (nano Particles) are formed.

  The case where an amphiphilic block polymer having a hydrophilic block having a sarcosine unit and a hydrophobic block having a lactic acid unit is used as an example of the amphiphilic block polymer will be described below.

  In the present invention, a molecular assembly (lactosome) is a structure formed by aggregation of the above linear or branched amphiphilic polymer or by self-assembled orientation. From the viewpoint of practicality, the present invention is preferably a micelle-shaped molecular assembly configured such that the inner side (core portion) is a hydrophobic block and the outer side (shell portion) is a hydrophilic block. By containing an appropriate metal ion, the molecular assembly of the present invention becomes a useful structure as a probe in molecular imaging or as a preparation in a drug delivery system.

  The branched amphiphilic block polymer has a larger molecular cross-sectional area at the hydrophilic portion than the linear amphiphilic block polymer due to the presence of a plurality of polysarcosine chains as branched chains. For this reason, the molecular assembly formed from the branched amphiphilic block polymer is excellent in stability as a particle. Furthermore, the particles can have a large curvature. For this reason, the molecular assembly composed of the branched block polymer has the basic feature that the size of the particles can be reduced.

  In addition, molecular aggregates composed of branched amphiphilic block polymers have a higher density of hydrophilic groups on the surface compared to linear lactosomes due to the presence of multiple polysarcosine chains as branched chains. It has the basic feature that sexual sites are less exposed.

[3. Preparation of molecular assembly]
The production of a molecular assembly (nanoparticle) composed of an amphiphilic block polymer having a hydrophilic block and a hydrophobic block will be described with reference to the drawings.

  In the present invention, a solution containing an amphiphilic block polymer having a hydrophilic block and a hydrophobic block in an organic solvent is introduced into a polymer solution supply channel to form a laminar flow of the polymer solution, and an aqueous liquid is used. At least two aqueous liquid supply channels are introduced to form a laminar flow of at least two aqueous liquids, and the laminar flow of the polymer solution is merged so as to be sandwiched between the laminar flows of the at least two aqueous liquids. Nanoparticles composed of a block polymer are formed.

  Examples of the organic solvent for dissolving the amphiphilic block polymer include trifluoroethanol, ethanol, hexafluoroisopropanol, dimethyl sulfoxide, dimethylformamide, and the like. The aqueous liquid means water or an aqueous solution. Distilled water, distilled water for injection, physiological saline, buffer solution and the like are used.

  FIG. 1 is a plan view schematically showing the confluence of a laminar flow of a polymer solution and a laminar flow of an aqueous liquid in the present invention. In FIG. 1, the joining portion J is configured such that the laminar flows Fw1 and Fw2 of the aqueous liquids from the left and right sides with respect to the flow direction of the polymer solution from the upstream to the downstream at the downstream end of the polymer solution supply channel Cp. Two aqueous liquid supply channels Cw1 and Cw2 are arranged with respect to the polymer solution supply channel Cp so as to sandwich the flow Fp. By adopting such a combined structure of the flow paths, the laminar flows (flows) Fw1 and Fw2 of the aqueous liquid sandwich the laminar flow (flow) Fp of the polymer solution. Then, the laminar flow Fp of the polymer solution mainly flows in the center of the flow channel from the junction J to the downstream nanoparticle formation flow channel Cn, and the laminar flows Fw1 and Fw2 of the aqueous liquid flow around the flow channel. It flows mainly through the part (the part in contact with the inner wall of the flow path). The flow velocity of the laminar flow Fp of the polymer solution is increased by flowing through the central portion of the flow path, and the area of the liquid-liquid interface with the laminar flows Fw1 and Fw2 of the aqueous liquid surrounding the flow increases. The self-assembly of the amphiphilic block polymer is considered to occur mainly at the liquid-liquid interface. By increasing the area of the liquid-liquid interface at the junction and increasing the flow velocity of the polymer solution laminar flow, the self-assembly of the amphiphilic block polymer is promoted and has a uniform particle size in the range of about 20 to 200 nm (ie, Nanoparticles are formed (the particle size distribution is unimodal).

  FIG. 2 is a schematic configuration diagram illustrating an example of a nanoparticle production apparatus. In FIG. 2, the nanoparticle production apparatus includes the microflow cell 1 having the above-described flow path merging structure, a means for supplying a polymer solution to the microflow cell 1, a means for supplying an aqueous liquid to the microflow cell 1, Means for recovering the nanoparticle-containing liquid from the microflow cell 1 are provided.

The microflow cell 1 is not particularly limited as long as it has the flow path merging structure shown in FIG. 1. The microflow cell 1 illustrated in FIG.
A polymer solution inlet Ip;
A polymer solution supply channel Cp connected to the polymer solution inlet Ip;
At least two aqueous liquid inlets Iw1, Iw2,
At least two aqueous liquid supply channels Cw1, Cw2 connected to the aqueous liquid inlets Iw1, Iw2, respectively;
A junction J where the polymer solution supply channel Cp and the at least two aqueous liquid supply channels Cw1, Cw2 merge;
A nanoparticle formation channel Cn located on the downstream side of the junction J,
A nanoparticle-containing liquid outlet On at the downstream end of the nanoparticle formation channel Cn;
Have
The junction J is formed by arranging the at least two aqueous liquid supply channels Cw1, Cw2 so as to sandwich the polymer solution supply channel Cp.

  The polymer solution supply means includes a polymer solution tank 11, a three-way valve 14 that includes a syringe pump 13 and is connected to the tank 11 via a conduit 12, and extends from the three-way valve 14 to the polymer solution inlet Ip of the microflow cell 1. And a pipe line 15 connected to the pipe.

  The aqueous liquid supply means includes an aqueous liquid tank 21, a three-way valve 24 that includes a syringe pump 23 and is connected to the tank 21 via a pipe 22, a pipe 25 that extends from the three-way valve 24, and the pipe 25 The pipes 26 and 27 are branched from and extended to two and connected to the aqueous liquid inlets Iw1 and Iw2 of the microflow cell 1, respectively.

  The means for collecting the nanoparticle-containing liquid has a conduit 30 extending from the nanoparticle-containing liquid outlet On of the microflow cell 1 and a nanoparticle-containing liquid recovery tank 31 connected to the conduit 30. .

FIG. 3 is a diagram showing details of the microflow cell.
The microflow cell 1 is not particularly limited as long as it includes the above elements. More specifically, referring to FIG. 3, the microflow cell 1 is
A substrate 101;
A resin film 102 disposed on the substrate 101 and formed with the polymer solution supply channel Cp, the at least two aqueous liquid supply channels Cw1, Cw2, the junction J, and the nanoparticle formation channel Cn; ,
The polymer solution inlet Ip is disposed on the resin film 102 and corresponds to the upstream end of the polymer solution supply channel Cp. The upstream ends of the at least two aqueous liquid supply channels Cw1 and Cw2 Cover sheet 103 in which at least two aqueous liquid inlets Iw1, Iw2 are formed at a position corresponding to, and the nanoparticle-containing liquid outlet On is formed at a position corresponding to the downstream end of the nanoparticle formation channel Cn;
Have
The substrate 101, the resin film 102, and the resin film 102 and the cover sheet 103 are joined in a liquid-tight state.

  That is, at the downstream end of the polymer solution supply flow path Cp, the joining portion J of the microflow cell 1 has a laminar flow (flow) of the aqueous liquid from the left and right sides with respect to the flow direction of the polymer solution from upstream to downstream. The two aqueous liquid supply channels Cw1 and Cw2 are arranged with respect to the polymer solution supply channel Cp so as to sandwich the laminar flow (flow) of the polymer solution.

  The substrate 101, the resin film 102, and the cover sheet 103 can be formed from a resin material. As the resin material, for example, cyclic polyolefin (COP) synthesized using cycloolefin as a monomer is preferable from the viewpoint of transparency and excellent thermocompression bonding. The thickness of each of the above is not particularly limited, but the substrate 101 is about 1 mm to 3 mm, for example about 2 mm, the resin film 102 is about 50 μm to 200 μm, for example about 100 μm, and the cover sheet 103 is about 200 μm to 1 mm, for example about 500 μm. It is good to be the thickness of. Since cyclic polyolefin (COP) is a non-polar material, it is subjected to surface modification such as ultraviolet irradiation or plasma treatment as appropriate, and then subjected to thermocompression bonding to each of the substrate 101, the resin film 102, and the resin film 102. And the cover sheet 103 may be joined in a liquid-tight state. Thermocompression bonding is a method of joining these members by press-contacting them at a temperature below the melting point to cause plastic deformation. Depending on the processing conditions of thermocompression bonding, the height of each flow path can be obtained according to the thickness of the resin film 102.

  The amphiphilic block polymer-containing solution in the polymer solution tank 11 is introduced into the polymer solution inlet Ip of the micro flow cell 1 while adjusting the flow rate with a syringe pump 13 and a three-way valve 14, and the polymer solution supply channel While supplying the laminar flow Fp of the polymer solution to the junction J through Cp, the microfluidic cell while adjusting the flow rate of the aqueous liquid in the aqueous liquid tank 21 with the syringe pump 23 and the three-way valve 24. It is introduced into one aqueous liquid inlet Iw1, Iw2, and the laminar flows Fw1, Fw2 of the two aqueous liquids are supplied to the junction J through the two aqueous liquid supply channels Cw1, Cw2. The laminar flow (flow) Fp of the polymer solution is joined so as to be sandwiched between the two laminar flows (flows) Fw1 and Fw2 of the aqueous solution. As described with reference to FIG. 1, the laminar flow Fp of the polymer solution flows mainly from the central portion of the flow path from the confluence J to the downstream nanoparticle formation flow path Cn, and the laminar flow Fw1, Fw2 mainly flows in the peripheral part of the flow path (the part in contact with the inner wall of the flow path). The flow velocity of the laminar flow Fp of the polymer solution is increased by flowing through the central portion of the flow path, and the area of the liquid-liquid interface with the laminar flows Fw1 and Fw2 of the aqueous liquid surrounding the flow increases. By increasing the area of the liquid-liquid interface at the junction and increasing the flow velocity of the polymer solution laminar flow, the self-assembly of the amphiphilic block polymer is promoted and has a uniform particle size in the range of about 20 to 200 nm (ie, Nanoparticles are formed (the particle size distribution is unimodal). The nanoparticle-containing liquid coming out from the nanoparticle-containing liquid outlet On is collected in the collection tank 31.

  The collected nanoparticle-containing liquid may be appropriately post-treated. As a post-processing step, a step of removing the organic solvent is performed. Furthermore, you may perform a refinement | purification process process suitably before the process of removing an organic solvent. As the purification treatment, for example, treatment such as gel filtration chromatography, filtering, and ultracentrifugation can be performed. In this way, a nanoparticle solution or dispersion can be obtained.

  The obtained nanoparticle solution or dispersion may be freeze-dried. A known method can be used as the freeze-drying method without any particular limitation. For example, the nanoparticle solution or dispersion obtained as described above can be frozen with liquid nitrogen and sublimated under reduced pressure. Thereby, a freeze-dried product of the molecular assembly is obtained. That is, the molecular assembly can be stored as a lyophilized product. If necessary, the molecular aggregate can be used for use by adding water or an aqueous solution to the lyophilized product to obtain a dispersion of the molecular aggregate. The water or aqueous solution is not particularly limited, and those skilled in the art may appropriately select a biochemically and pharmaceutically acceptable one. Examples thereof include distilled water for injection, physiological saline, and buffer solution.

[4. Particle size of molecular assembly]
The particle diameter of the molecular assembly (nanoparticle) produced in the present invention is, for example, 10 to 200 nm. Here, the “particle diameter” means a particle diameter having the highest frequency of appearance in the particle distribution, that is, a central particle diameter. The method for measuring the size of the molecular assembly of the present invention is not particularly limited, and can be appropriately selected by those skilled in the art. Examples thereof include an observation method using a transmission electron microscope (TEM) or an atomic force microscope (AFM), a dynamic light scattering (DLS) method, and the like. In the DLS method, the migration diffusion coefficient of particles that are in Brownian motion in a solution is measured. In the embodiment of the present specification, the dynamic light scattering method is used.

  The particle diameter of the nanoparticles changes the introduction flow rate of the polymer solution and the introduction flow rate of the aqueous liquid, and the flow rate of the laminar flow Fp of the polymer solution in the junction J and the laminar flow of the aqueous liquid surrounding it. It can be controlled by changing the flow velocity of Fw1 and Fw2 and changing the area of the liquid-liquid interface. By increasing the total introduction flow rate of the polymer solution and the aqueous solution, it is possible to obtain nanoparticles having a smaller particle diameter and nanoparticles exhibiting a unimodal particle size distribution.

  For example, as shown in the Examples, in the case of a lactosome composed of a linear amphiphilic block polymer having a hydrophilic block composed of a sarcosine unit and a hydrophobic block composed of a lactic acid unit, the downstream side of the junction J When the total flow rate of the polymer solution and the aqueous liquid in the nanoparticle formation channel Cn is increased from 1000 μL / min to 3000 μL / min, the particle size of the obtained nanoparticles decreases from 115 nm to 43 nm, and The unimodality of the particle size distribution is increased. In this way, the particle size of the resulting nanoparticles can be controlled.

  Moreover, if the hydrophilic block in an amphiphilic block polymer is a branched structure, the particle diameter of the particle | grains comprised from them will become small compared with a linear type. For example, in the case of lactosomes, the particle diameter of particles made of a linear polymer can be about 35 to 200 nm, whereas the particle diameter of particles made of a branched polymer can be about 10 to 30 nm. The particle diameter can be further controlled by using a linear polymer and a branched polymer in combination and changing the ratio. The smaller the particle diameter (for example, 50 nm or less), the easier it is to obtain the EPR effect when administered in vivo.

[5. Drug delivery system and molecular imaging]
In the present invention, when producing nanoparticles, the polymer solution can contain a drug and / or labeling agent to obtain nanoparticles containing the drug and / or labeling agent. In this case, the drug and / or labeling agent is soluble in the organic solvent. Moreover, when producing a nanoparticle, a chemical | medical agent and / or a labeling agent can be contained in the said aqueous liquid, and the nanoparticle containing a chemical | medical agent and / or a labeling agent can be obtained. In this case, the drug and / or labeling agent is soluble in water. The drug and / or labeling agent may be appropriately selected by those skilled in the art according to the purpose.

[5-1. Target of administration of molecular assembly]
In the present invention, the drug delivery system and molecular imaging include administering the above-described molecular assembly into a living body. The living body to which the molecular assembly is administered is not particularly limited, and may be a human or non-human animal. Non-human animals are not particularly limited, but mammals other than humans, more specifically, primates, rodents (mouse, rats, etc.), rabbits, dogs, cats, pigs, cows, sheep, horses, etc. Can be mentioned.

  The molecular assembly used in the method of the present invention is excellent in specific accumulation at a vascular lesion site (for example, a malignant tumor site, an inflammatory site, an arteriosclerotic site, an angiogenic site, etc.). Since the molecular assembly of the present invention accumulates in tissues at these sites due to the EPR (enhanced permeability and retention) effect, the accumulation does not depend on the type of tissue at the vascular lesion site. The administration target of the fluorescent probe of the present invention is preferably a cancer. There are a wide variety of cancers that can be the target of administration. For example, liver cancer, pancreatic cancer, lung cancer, cervical cancer, breast cancer, colon cancer and the like can be mentioned.

[5-2. Administration]
The method of administration into the living body is not particularly limited, and can be appropriately determined by those skilled in the art. Therefore, the administration method may be systemic administration or local administration. That is, the molecular probe can be administered by any of injection (needle-type, needle-free), internal use, and external use.

[5-3. Detection of molecular assembly]
In the present invention, molecular imaging includes a step of detecting a signal derived from an administered molecular assembly. By detecting the administered molecular assembly, the state of the administration target (particularly the position and size of the tissue such as cancer) can be observed from outside the body. As a detection method, any means capable of visualizing the administered molecular assembly can be used. The detection means can be appropriately determined by those skilled in the art according to the type of labeling agent possessed by the molecular assembly.

  Those skilled in the art can appropriately determine the time from administration to the start of detection. For example, it can be 1 to 24 hours after administration. The amount of lactosome accumulated in the tumor part and other than the tumor part and the temporal change of the accumulation amount are examined by the detection means.

  In addition, it is preferable to detect the molecular assembly from the viewpoint of accuracy by measuring from a plurality of directions, not from one direction of the living body. Specifically, it is preferable to perform measurement from at least three directions, more preferably from at least five directions. When performing measurement from five directions, for example, measurement can be performed from the left and right abdominal sides, from both the left and right bodies, and from the back side.

  Examples are shown below to explain the present invention in more detail, but the present invention is not limited to these Examples.

[Straight-chain amphiphilic block polymer (PLLA _39- PSar ₇₄ )]
In the examples, a linear amphiphilic block polymer (PLLA ₃₉ -PSar ₇₄ ) having a hydrophilic block composed of 74 sarcosine units and a hydrophobic block composed of 39 L-lactic acid units was used. The synthesis of the polymer was performed by referring to the methods described in WO2009 / 148121 and WO2012 / 17685, from sarcosine-NCA (Sar-NCA) and aminated poly-L-lactic acid (a-PLLA), glycolic acid, O- (benzotriazol-1-yl) -N, N, N ′, N′-tetramethyluronium hexafluorophosphate (HATU) and N, N-diisopropylethylamine (DIEA) were used.

[Example 1]
Using the apparatus shown in FIGS. 1 to 3, nanoparticles were produced from a linear amphiphilic block polymer (PLLA ₃₉ -PSar ₇₄ ) as follows.

As water 21, Milli-Q was used. As the polymer solution 11, an amphiphilic block polymer (PLLA ₃₉ -PSar ₇₄ ) was dissolved in N, N-dimethylformamide (DMF) at a concentration of 8 mg / mL, stirred at 60 ° C. for 30 min in an oil bath, and brought to room temperature. What used the temperature was used.

  In the illustrated apparatus, a syringe pump 14, 24 (Hamilton PSD / 3) is used for liquid feeding, and a micro fixed to a jig via each Teflon (registered trademark) tube 12, 15, 22, 25, 26, 27. Two liquids of the polymer solution 11 and the aqueous liquid 21 were introduced into the flow cell 1. A heater and a thermocouple are installed in the jig, and the micro flow cell 1 can be heated. The syringe pumps 14 and 24 were connected to a personal computer through a controller, and the flow rate was set by the personal computer. First, the inside of the flow path Cn downstream from the junction J was filled with water, and then the polymer solution was fed. After discarding 500 μL of the initial flow, sampling was started. In addition, the capacity | capacitance of the syringe was 2.5 mL, and liquid feeding was stopped when all the water flowed. The particle size and particle size distribution of the obtained sample were measured by DLS (Malvern Zetasizer Nano S).

The flow rate ratio FRR (Flow Rate Ratio) of water to the polymer solution is
The flow rate of the polymer solution is Qp,
Let Qw be the flow rate of water,
FRR = Qw / Qp
It is represented by In the examples, FRR = 9. The total flow rate Qt = Qw + Qp of the combined solution of the polymer solution and water. Further, water was distributed from the pipeline 25 to the pipelines 26 and 27 via the bifurcated connector so that the flow rates of water to the aqueous liquid supply channels Cw1 and Cw2 were equal.

  The microflow cell used in Example 1 had a channel width: 700 μm, a channel length: 611 mm, a channel volume: 29 μL, and the number of turns in the nanoparticle formation channel Cn downstream from the junction J was 14. The flow path temperature of the micro flow cell 1 was set to 25 ° C. In addition, as for the micro flow cell 1, with reference to FIG. 3, as for the board | substrate 101, the resin film 102, and the cover sheet 103, all are cyclic polyolefin resin (Zeonor 1600R, glass transition temperature Tg: 161 degreeC, the Nippon Zeon Corporation make). The thickness of the substrate 101 was 2 mm, the thickness of the resin film 102 was 100 μm, and the thickness of the cover sheet 103 was 500 μm.

  (A) First, under the condition of FRR = 9, the polymer solution supply flow path Cp and the two aqueous liquid supplies are supplied so that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rate of the polymer solution and water is 1000 μL / min. A polymer solution and water were introduced into the channels Cw1 and Cw2. The nanoparticle-containing liquid was recovered 31 from the downstream end of the nanoparticle formation channel Cn. The collected nanoparticle-containing liquid was diluted 2-fold with Milli-Q. This diluted solution was passed through a filter of 200 nm [PALL Acrodisc (registered trademark) 25 mm Syringe Filter w / 0.2 μm Supor (registered trademark) Membrane], and DLS measurement was performed on the filtered solution.

  The DLS measurement result is shown in FIG. The horizontal axis is the particle diameter [nm], and the vertical axis is the intensity [%]. A main peak was observed at 115 nm and a minor peak was observed at 37 nm. The PdI value representing the polydispersity of the particle size distribution was 0.19.

  (B) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the two aqueous liquids are set so that the total flow rate Qt = Qw + Qp of the combined solution of the polymer solution and water is 2000 μL / min. DLS (Malvern Instruments Ltd, Zetasizer Nano S) measurement was performed in the same manner as in (a) except that the polymer solution and water were introduced into the supply channels Cw1 and Cw2.

  The DLS measurement result is shown in FIG. The main peak was observed at 47 nm and clearly showed unimodality. The PdI value was 0.13.

  (C) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the two aqueous liquids are set so that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rates of the polymer solution and water is 3000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the supply channels Cw1 and Cw2.

  The DLS measurement result is shown in FIG. The main peak was observed at 43 nm and clearly showed a single peak. The PdI value was 0.14.

  Thus, by increasing the total flow rate Qt of the liquid, the finer and unimodality of the nanoparticles was achieved.

[Comparative Example 1]
The same operation as in Example 1 was performed except that a microflow cell having a Y-shaped flow path merging structure was used instead of the microflow cell 1 of the apparatus shown in FIGS. A schematic flow path structure of the micro flow cell is shown in FIG. FIG. 6 is a plan view schematically showing the merge of the laminar flow of the polymer solution and the laminar flow of the aqueous liquid.

  5D and 6, the polymer solution supply channel Cp and one aqueous liquid supply channel Cw merge at the junction J, and the nanoparticle formation channel Cn downstream from the junction J A Y-shape is formed. That is, in the merging portion J, the laminar flow Fw of the aqueous solution pushes the laminar flow Fp of the polymer solution from the left side only with respect to the flow direction of the polymer solution from upstream to downstream toward the inner wall surface side of the nanoparticle formation channel Cn. As described above, one aqueous liquid supply channel Cw is disposed with respect to the polymer solution supply channel Cp. In such a flow path merging structure, the laminar flow (flow) Fp of the polymer solution cannot flow in the central portion of the flow path but flows mainly in a portion in contact with the inner wall of the flow path. Therefore, the flow rate of the laminar flow Fp of the polymer solution does not increase, and the area of the liquid-liquid interface with the laminar flow Fw of the aqueous liquid does not increase. Therefore, such a merging structure does not promote the self-assembly of the amphiphilic block polymer and is inferior to the unimodality of the particles.

  The microflow cell used in Comparative Example 1 had a channel width: 700 μm, a channel length: 611 mm, a channel volume: 28 μL, and the number of turns in the nanoparticle formation channel Cn downstream from the junction J was 14. The flow path temperature of the micro flow cell was 25 ° C.

  (A) First, under the condition of FRR = 9, the polymer solution supply channel Cp and the aqueous liquid supply channel are set so that the total flow rate Qt = Qw + Qp of the solution obtained by combining the polymer solution and water flow rate is 1000 μL / min. Except that the polymer solution and water were introduced into Cw, the same operation as in Example 1 (a) was performed, and DLS measurement was performed.

  The DLS measurement result is shown in FIG. A main peak was observed at 98 nm, and a smaller peak was also observed. The PdI value was 0.16.

  (B) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the aqueous liquid supply flow are set such that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rates of the polymer solution and water is 2000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the path Cw.

  The DLS measurement result is shown in FIG. A main peak was observed at 85 nm, and a smaller peak was also observed. The PdI value was 0.17.

  (C) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the aqueous liquid supply flow are set so that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rates of the polymer solution and water is 3000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the path Cw.

  The DLS measurement result is shown in FIG. A main peak was observed at 82 nm, and a smaller peak was also observed. The PdI value was 0.18.

  Thus, even if the total flow rate Qt of the liquid was increased, the nanoparticles were hardly miniaturized. Further, when the total liquid flow rate Qt was increased, the PdI value was slightly increased, and the polydispersity was increased.

[Example 2]
1-3, except that a microflow cell having the same number of turns in the nanoparticle formation flow path Cn is used, except that the flow path merge structure is the same. The same operation as in Example 1 was performed. A schematic flow path structure of the micro flow cell is shown in FIG.

  The microflow cell used in Example 2 had a channel width: 700 μm, a channel length: 612 mm, a channel volume: 29 μL, and the number of turns in the nanoparticle formation channel Cn downstream from the junction J was 28. The flow path temperature of the micro flow cell was 25 ° C.

  (A) First, under the condition of FRR = 9, the polymer solution supply flow path Cp and the two aqueous liquid supplies are supplied so that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rate of the polymer solution and water is 1000 μL / min. A polymer solution and water were introduced into the channels Cw1 and Cw2. The same operation as in Example 1 (a) was performed to perform DLS measurement.

  The DLS measurement result is shown in FIG. A main peak was observed at 124 nm, and a smaller peak of 30 nm was also observed. The PdI value was 0.15.

  (B) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the two aqueous liquids are set so that the total flow rate Qt = Qw + Qp of the combined solution of the polymer solution and water is 2000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the supply channels Cw1 and Cw2.

  The DLS measurement result is shown in FIG. The main peak was observed at 46 nm and clearly showed unimodality. The PdI value was 0.13.

  (C) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the two aqueous liquids are set so that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rates of the polymer solution and water is 3000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the supply channels Cw1 and Cw2.

  The result of DLS measurement is shown in FIG. The main peak was observed at 43 nm and clearly showed a single peak. The PdI value was 0.14.

  Thus, by increasing the total flow rate Qt of the liquid, the finer and unimodality of the nanoparticles was achieved. Moreover, from the comparison with Example 1, it has confirmed that the confluence | merging structure of a flow path was an important factor for the refinement | miniaturization of a nanoparticle, and unimodality. The number of turns of the nanoparticle formation channel Cn after merging was not so important.

[Comparative Example 2]
In place of the micro flow cell 1 of the apparatus shown in FIGS. 1 to 3, the merge structure of the flow path is a Y-shaped structure as in Comparative Example 1, and the number of turns of the nanoparticle formation flow path Cn is doubled. The same operation as in Example 1 was performed except that the microflow cell thus prepared was used. A schematic flow channel structure of the micro flow cell is shown in FIG.

  The microflow cell used in Comparative Example 2 had a channel width: 700 μm, a channel length: 612 mm, a channel volume: 28 μL, and the number of turns in the nanoparticle formation channel Cn downstream from the merged portion was 28. The flow path temperature of the micro flow cell was 25 ° C.

  (A) First, under the condition of FRR = 9, the polymer solution supply channel Cp and the aqueous liquid supply channel are set so that the total flow rate Qt = Qw + Qp of the solution obtained by combining the polymer solution and water flow rate is 1000 μL / min. Except that the polymer solution and water were introduced into Cw, the same operation as in Example 1 (a) was performed, and DLS measurement was performed.

  The DLS measurement result is shown in FIG. The main peak was observed at 120 nm, and a smaller peak of 40 nm was also observed. The PdI value was 0.18.

  (B) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the aqueous liquid supply flow are set such that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rates of the polymer solution and water is 2000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the path Cw.

  The DLS measurement result is shown in FIG. The main peak was observed at 81 nm, and a shoulder was also observed in a smaller area. The PdI value was 0.16.

  (C) Next, under the condition of FRR = 9, the polymer solution supply flow path Cp and the aqueous liquid supply flow are set so that the total flow rate Qt = Qw + Qp of the liquid obtained by combining the flow rates of the polymer solution and water is 3000 μL / min. DLS measurement was performed by performing the same operation as in the above (a) except that the polymer solution and water were introduced into the path Cw.

  The DLS measurement result is shown in FIG. A main peak was observed at 71 nm. The PdI value was 0.15.

  Thus, even when the total flow rate Qt of the liquid was increased, the fineness of the nanoparticles was small as compared with Example 2.

[Study on flow in flow path by simulation]
[Confluence structure of the flow path consistent with the present invention]
As described above, in the case of having a flow path confluence structure consistent with the present invention, it has been demonstrated that nanoparticle refinement and unimodality were achieved by increasing the total liquid flow rate Qt. This result was examined by a simulation method. For the simulation, 2D simulation was performed using COMSOL Multiphysics 4.2a. Various parameters were input according to COMSOL Multiphysics 4.2a. The concentration of the polymer solution was 8 mg / mL, and FRR = Qw / Qp = 9.

  A simulation of the merging structure of the flow path shown in FIG. 1 consistent with the present invention is shown in FIG. FIG. 9A is basically the same as that shown in FIG. The laminar flow Fp of the polymer solution and the laminar flows Fw1 and Fw2 of the aqueous liquid with respect to the position in the inner diameter width direction of the pipe line Cn near the nanoparticle formation channel Cn immediately downstream from the junction J A simulation was performed on the flow rate. FIG. 9B is a graph showing the simulation results, and the horizontal axis represents the position [Channel Width, Wc (μm)] in the inner diameter width direction as viewed from the arrow A side in the inner diameter width direction of the pipe Cn. The axis represents the laminar flow velocity [Flow Rate, Vt (m / sec)] at the position in the width direction.

  From FIG. 9B, the flow rate of the laminar flow Fp of the polymer solution at the interface between the laminar flow Fp of the polymer solution flowing in the center of the flow path and the laminar flows Fw1 and Fw2 of the aqueous liquid is expressed as follows. As the total flow rate Qt of the liquid with the combined flow rate increased from 1000 μL / min to 2000 μL / min and 3000 μL / min, it increased from about 0.4 to about 0.85 and about 1.4. That is, this simulation result shows that the flow velocity of the laminar flow Fp of the polymer solution is increased by flowing through the central portion of the flow path Cn, and the area of the liquid-liquid interface with the laminar flows Fw1 and Fw2 of the aqueous liquid surrounding it. Indicates an increase. The increase in the area of the liquid-liquid interface at the junction and the increase in the flow velocity of the polymer solution laminar flow facilitates self-organization of the amphiphilic block polymer and has a uniform particle size (that is, the particle size distribution is unimodal). The simulation results also confirmed that nanoparticles can be formed. This simulation result coincides with the results of Examples 1 and 2.

[Confluence structure of Y-shaped flow path not conforming to the present invention]
FIG. 10 shows a simulation of the merging structure of the Y-shaped channel shown in FIG. 6 that does not match the present invention. FIG. 10A is basically the same as that shown in FIG. About the flow velocity of the laminar flow Fp of the polymer solution and the laminar flow Fw of the aqueous liquid with respect to the position in the inner diameter width direction of the pipe line Cn near the nanoparticle formation channel Cn immediately downstream from the junction J A simulation was performed. FIG. 10B is a graph showing the simulation results, and the horizontal axis represents the position in the inner diameter width direction [Channel Width, Wc (μm)] viewed from the arrow B side in the inner diameter width direction of the pipe Cn. The axis represents the laminar flow velocity [Flow Rate, Vt (m / sec)] at the position in the width direction.

  From FIG. 10B, the flow rate of the laminar flow Fp of the polymer solution at the interface between the laminar flow Fp of the polymer solution flowing on the inner wall side of the nanoparticle formation channel Cn and the laminar flow Fw of the aqueous liquid Even if the total flow rate Qt of the combined solution and water flow rate is increased from 1000 μL / min to 2000 μL / min and 3000 μL / min, it increases only from about 0.2 to about 0.4 and about 0.6. It was. That is, this simulation result shows that the flow rate of the laminar flow Fp of the polymer solution flows on the inner wall surface side of the flow path Cn, and therefore is slightly faster than the case where it flows through the center of the flow path Cn. It shows that the area of the liquid-liquid interface between the laminar flow Fp and the laminar flow Fw of the aqueous liquid does not increase. Therefore, in such a merging structure, the self-assembly of the amphiphilic block polymer was not promoted, and it was confirmed by the simulation results that the unimodality of the particles was inferior. This simulation result coincides with the results of Comparative Examples 1 and 2.

J: Junction part Cp: Polymer solution supply flow path Cw1, Cw2: Aqueous liquid supply flow path Cn: Nanoparticle formation flow path Fw1, Fw2: Laminar flow of aqueous liquid Fp: Laminar flow of polymer solution

Claims (13)

A method for producing nanoparticles comprising an amphiphilic block polymer having a hydrophilic block and a hydrophobic block,
A solution containing an amphiphilic block polymer having a hydrophilic block and a hydrophobic block in an organic solvent is introduced into the polymer solution supply channel to form a laminar flow of the polymer solution,
Introducing an aqueous liquid into at least two aqueous liquid supply channels to form a laminar flow of at least two aqueous liquids;
The method for producing nanoparticles, wherein the laminar flow of the polymer solution is merged so as to be sandwiched between the laminar flows of the at least two aqueous liquids to form nanoparticles composed of an amphiphilic block polymer. A polymer solution inlet;
The polymer solution supply channel connected to the polymer solution inlet;
At least two aqueous liquid inlets;
The at least two aqueous liquid supply channels respectively connected to the aqueous liquid inlet;
A merge part where the polymer solution supply channel and the at least two aqueous liquid supply channels merge;
A nanoparticle formation channel located downstream of the confluence, and
A nanoparticle-containing liquid outlet at the downstream end of the nanoparticle formation channel;
Have
The merging portion uses a micro flow cell formed by arranging the at least two aqueous liquid supply channels so as to sandwich the polymer solution supply channel,
Introducing the amphiphilic block polymer-containing solution from the polymer solution inlet, supplying a laminar flow of the polymer solution to the junction through the polymer solution supply channel,
An aqueous liquid is introduced from the at least two aqueous liquid inlets, and a laminar flow of the at least two aqueous liquids is supplied to the junction through the at least two aqueous liquid supply channels.
While the laminar flow of the polymer solution and the laminar flow of the aqueous liquid are brought into contact with each other toward the downstream side of the nanoparticle formation flow path from the confluence, nanoparticles formed of an amphiphilic block polymer are formed,
The method for producing nanoparticles according to claim 1, wherein a liquid containing the formed nanoparticles is obtained from the nanoparticle-containing liquid outlet. The microflow cell is
A substrate,
A resin film disposed on the substrate and formed with the polymer solution supply channel, the at least two aqueous liquid supply channels, the junction, and the nanoparticle formation channel;
The polymer solution inlet is formed at a position corresponding to the upstream end of the polymer solution supply flow path disposed on the resin film, and at least at a position corresponding to the upstream end of each of the at least two aqueous liquid supply flow paths. Two aqueous liquid inlets are formed, a cover sheet in which the nanoparticle-containing liquid outlet is formed at a position corresponding to the downstream end of the nanoparticle formation flow path,
Have
The method for producing nanoparticles according to claim 2, wherein the substrate, the resin film, and the resin film and the cover sheet are bonded in a liquid-tight state.   The merging portion of the microflow cell has a laminar flow of the aqueous solution from the left and right sides with respect to the flow direction of the polymer solution from upstream to downstream at the downstream end of the polymer solution supply channel. The method for producing nanoparticles according to claim 2 or 3, wherein the two aqueous liquid supply channels are arranged with respect to the polymer solution supply channel so as to sandwich the polymer solution.   The nanoparticle production according to any one of claims 1 to 4, wherein the amphiphilic block polymer has a hydrophilic block having an alkylene oxide unit and / or a sarcosine unit and a hydrophobic block having a hydroxy acid unit. Method.   The said amphiphilic block polymer is a manufacturing method of the nanoparticle in any one of Claims 1-5 which has a hydrophilic block which has a sarcosine unit, and a hydrophobic block which has a lactic acid unit.   The method for producing nanoparticles according to claim 6, wherein the total number of sarcosine units contained in the hydrophilic block is 2 to 300.   The method for producing nanoparticles according to claim 6 or 7, wherein the number of lactic acid units contained in the hydrophobic block is 5 to 400.   The manufacturing method of the nanoparticle in any one of Claims 1-8 whose particle diameter of the nanoparticle formed is 10-200 nm.   The method for producing nanoparticles according to any one of claims 1 to 9, wherein the particle size distribution of the formed nanoparticles exhibits unimodality.   The method for producing nanoparticles according to any one of claims 1 to 10, wherein a drug and / or labeling agent is contained in the polymer solution to obtain nanoparticles containing the drug and / or labeling agent.   The method for producing nanoparticles according to any one of claims 1 to 11, wherein the aqueous liquid contains a drug and / or a labeling agent to obtain nanoparticles containing the drug and / or the labeling agent. A microflow cell for producing nanoparticles composed of an amphiphilic block polymer having a hydrophilic block and a hydrophobic block,
At least one polymer solution inlet;
At least one polymer solution supply channel connected to the polymer solution inlet;
At least two aqueous liquid inlets;
At least two aqueous liquid supply channels respectively connected to the aqueous liquid inlets;
A merge part where the polymer solution supply channel and the at least two aqueous liquid supply channels merge;
A nanoparticle formation channel located downstream of the confluence, and
A nanoparticle-containing liquid outlet at the downstream end of the nanoparticle formation channel;
Have
The junction part is a micro flow cell in which the at least two aqueous liquid supply channels are arranged so as to sandwich the polymer solution supply channel.