JP2018145115A - Polymer composite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means that enables a drug to be encapsulated in a support stably, and also enables drug delivery to a desired target tissue (for example, brain tissue) and drug release in the tissue.SOLUTION: A polymer composite contains a block copolymer having a polymer segment having at least one boronic acid group selected from a phenylboronic acid group or a pyridylboronic acid group in a side chain, and a hydrophilic polymer segment, and a low molecular drug having a binding site to the boronic acid group.SELECTED DRAWING: None

Description

  The present invention relates to polymer composites and drug delivery devices. Specifically, the present invention relates to a polymer complex and a drug delivery device for delivering a small molecule drug to a target site.

  Drug delivery system (DDS) is a technology that selectively delivers the minimum amount of drug to the required site when needed, thereby maximizing the effect of the drug and reducing side effects. The purpose is to minimize. In order to selectively release a drug at the target site, a technique is required that can stably hold the drug without being absorbed or decomposed until it reaches the target site and can release the drug at the target site. is there.

  Attempts to use a drug carrier incorporating various drugs in a carrier as a DDS have been actively studied, and some have already been clinically applied. Liposomes, microparticles, and various polymers are used as carriers for transporting drugs. Various drugs can be used through non-covalent bonds (hydrophobic interactions, electrostatic interactions, etc.) or covalent bonds. A technology for supporting a carrier is proposed. Various studies have been conducted on drug release control technology, and drug release is controlled by autonomous responses to various stimuli such as physical stimuli such as temperature, electric field, magnetic field, and ultrasound, and environmental stimuli such as pH change. Technology has been developed.

  For example, Patent Document 1 and Non-Patent Document 1 describe a polymer micelle formed by self-organizing a block copolymer of a hydrophilic polymer segment such as polyethylene glycol (PEG) and a cationic polymer segment such as polyamino acid. Furthermore, an environment-responsive complex in which a nucleic acid is supported using a phenylboronic acid group has been proposed. In the complex, after entering the cytoplasm, the encapsulated nucleic acid can be released by replacement with other molecules such as ATP and ribonucleic acid present in the cytoplasm.

  As sites targeted by DDS, there are various tissues and cells such as cancer cells, tumor tissues, and inflammatory tissues. In recent years, research on techniques for delivering drugs to the brain has been promoted. Between the blood and the brain, there is an in vivo barrier called the blood-brain barrier (BBB) that restricts substance exchange. Due to the high permeation selectivity of the BBB, drug transport from the blood to the brain parenchyma has been severely restricted, making drug delivery to the brain very difficult.

  In general, (1) low molecular weight (500 Da or less), (2) high fat-soluble compounds can pass through the BBB, so for the purpose of delivery to the brain, low hydrophobic molecular weight compounds Drug development and screening are in progress. However, at present, there are still very limited drugs that can break through the BBB and be delivered into the brain even with low-molecular weight compounds with high hydrophobicity.

International Publication No. 2013/073697

Mitsuru Naito, Takehiko Ishii, Akira Matsumoto, Kanjiro Miyata, Yuji Miyahara, Kazunori Kataoka; A Phenylboronate Functionalized Chemie International Edition, Vol.51, 2012: 10751-10755, doi: 10.1002 / anie.201203360.

  There is still a need for a technique that allows a drug to be stably supported on a carrier and enables the drug to be released at a target site.

  As a result of intensive studies to solve the above problems, the present inventors have combined a polymer having a specific boronic acid group in the side chain with a low molecular weight drug containing a binding site for the boronic acid group. The present invention has been completed. That is, the present invention is as follows, for example.

[1] A block copolymer having a polymer segment having at least one boronic acid group selected from a phenylboronic acid group or a pyridylboronic acid group in a side chain, and a hydrophilic polymer segment;
A low molecular weight drug comprising a binding site with the boronic acid group;
A polymer composite comprising
[2] The binding site with the boronic acid group is at least one selected from a polyol structure, a diamine structure, a hydroxyamine structure, a hydroxamic acid structure, an alkoxycarboxyamide structure, and a diphosphate structure. The complex described.
[2-1] The complex according to [2], wherein the binding site has a 1,2-diol structure.
[2-2] The complex according to [2], wherein the binding site with the boronic acid group is at least one selected from the following structures 2 to 44.

[2-3] The ratio of the low molecular weight drug to the boronic acid group (drug / BA ratio) is 0.05 to 1, [1] to [2], [2-1], [2- 2].
[3] The complex according to [1] or [2], wherein the low molecular drug is a hydrophobic substance.
[4] The block copolymer is arranged radially so that the polymer segment is on the inside and the hydrophilic polymer segment is on the outside to form micelles, and the low-molecular drug is encapsulated in the micelles. , [1] to [3].
[5] The complex according to any one of [1] to [4], wherein the polymer segment is composed of a polyamino acid, and the boronic acid group is introduced into a side chain of the polyamino acid.
[5-1] The polyamino acid is a nonpolar amino acid such as leucine, isoleucine, phenylalanine, methionine, or tryptophan; an acidic amino acid such as aspartic acid or glutamic acid; a basic amino acid such as lysine, ornithine, arginine, homoarginine, or histidine; And a derivative thereof; and a complex according to any one of [1] to [5], which is a polymer of an amino acid selected from a combination thereof.
[5-2] The boronic acid group is an amide bond, carbamoyl bond, alkyl bond, ether bond, ester bond, thioester bond, thioether bond, sulfonamide bond, urethane bond, sulfonyl bond, thymine bond, urea bond, thiourea bond. And the complex according to any one of [1] to [5] and [5-1], which is introduced into a side chain of the polyamino acid via a linking group selected from a combination thereof.
[6] The hydrophilic polymer segment includes poly (ethylene glycol), polysaccharide, poly (vinyl pyrrolidone), poly (vinyl alcohol), poly (acrylamide), poly (acrylic acid), poly (methacrylamide), poly (Methacrylic acid), poly (methacrylic acid ester), poly (acrylic acid ester), polyethyl acrylate, poly (hydroxy ethyl methacrylate), polyamino acid, poly (malic acid), poly (2-methyl-2- Any of [1] to [5] composed of a hydrophilic polymer selected from oxazoline), poly (2-ethyl-2-oxazoline), poly (2-isopropyl-2-oxazoline), or derivatives thereof A complex according to any one of the above.
[7] Any of [1] to [6], wherein the boronic acid group is a phenylboronic acid group (PBA) represented by the following formula (b1) or a pyridylboronic acid group represented by the following formula (b2). A complex according to any one of the above.
(In the above formula,
R _b represents halogen selected from fluorine, chlorine, bromine, or iodine, or nitro;
n is an integer from 0 to 4,
* Indicates the point of attachment to the polymer chain)
[7-1] The composite according to [7], wherein the boronic acid group is a phenylboronic acid group (PBA) represented by the following formula (b11) or a pyridylboronic acid group represented by the following formula (b21). body.
(In the above formula,
n is an integer of 1 to 4,
* Indicates the point of attachment to the polymer chain)
[7-2] The binding site has a diphosphate structure (preferably the structure of 44 above), and the boronic acid group is a pyridylboronic acid group represented by the above formula (b11). [7] The complex described in 1.
[7-3] The complex according to [7], wherein the binding site has a 1,2-diol structure, and the boronic acid group is a pyridylboronic acid group represented by the above formula (b21).
[8] The composite according to any one of [1] to [7], wherein the block copolymer is represented by the following formula (3).
(Where
R ¹ is a hydrogen atom or an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms;
R ² represents a hydrogen atom, an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms, or an unsubstituted or substituted linear or branched alkylcarbonyl group having 1 to 24 carbon atoms. Group,
R ^4a is, independently of one another, a methylene group or an ethylene group,
L ¹ is —SS— or a valence bond,
L ² is —NH—, —O—, —O (CH ₂ ) _p1 —NH—, or —L ^2a — (CH ₂ ) _q1 -L ^2b —, wherein p1 and q1 are Independently, an integer from 1 to 5, L ^2a is OCO, OCONH, NHCO, NHCOO, NHCONH, CONH or COO, L ^2b is NH or O,
R ^9a is a divalent group represented by —NH— (CH ₂ ) _{p 2} — [NH— (CH ₂ ) _{q 2} —] _r 2 NH—, and p 2, q 2, and r 2 are independently from each other. , An integer from 1 to 5,
R ^9b is —NH— (CH ₂ ) _{p 3} — [NH— (CH ₂ ) _{q 3} —] _{r 3} NH ₂ , and p 3, q 3 and r 3 are each independently an integer of 1 to 5 Yes BA represents a boronic acid group x is 0.1 to 0.9,
m is an integer of 1 to 300. )
[9] The complex according to any one of [1] to [8], wherein the surface of the complex is modified with glucose or a glucose derivative.
[10] A composition comprising the complex according to any one of [1] to [9].
[11] The composition according to [10], wherein the low molecular drug is released from the polymer complex in the presence of reactive oxygen species.
[11-1] The composition according to [11], wherein the low molecular drug is released from the polymer complex in the presence of 1 mM or more of H ₂ O ₂ .
[12] The composition according to [10] or [11], which is used for delivering the small molecule drug to the brain.
[13] A drug delivery device comprising the complex according to any one of [1] to [9] or the composition according to any one of [10] to [12].

The present invention has one or more of the following effects.
(1) Provided is a polymer complex in which a low molecular drug containing a binding site with a boronic acid group is stably supported in a polymer and can be released by oxidation with an active oxygen species.
(2) Drug delivery to a desired target tissue (for example, brain parenchyma) and drug release in the tissue become possible.
(3) Drug release control depending on the concentration of reactive oxygen species in the target tissue becomes possible.
(4) A polymer micelle encapsulating a drug can be formed.

1 is a schematic diagram of a polymer composite according to an embodiment of the present invention. (A) shows each component, (b) shows the formed polymer complex (drug-containing polymer micelle). It is a schematic diagram showing formation of a bond between a fluorinated phenylboronic acid group (FPBA) and a 1,2-diol structure of rutin. 1 is a schematic diagram of a brain delivery system of drug-encapsulating polymer micelles that self-cleavage in response to oxidative stress by reactive oxygen species (ROS). FIG. Dynamic light scattering (DLS) of the polymeric micelle (Rutin / FPBA = 0.25) prepared in Example 2 using the block copolymer (2k-45-22.7%) prepared in Example 1 It is a figure which shows the measurement result of the particle size distribution by a method. Transmission electron microscope (TEM) of the polymer micelle (Rutin / FPBA = 0.25) prepared in Example 2 using the block copolymer (2k-45-22.7%) produced in Example 1 It is a figure which shows an image. Dynamic light scattering (DLS) of the polymer micelle (Rutin / FPBA = 0.1) prepared in Example 2 using the block copolymer (2k-70-23.3%) produced in Example 1 It is a figure which shows the time-dependent change (under different pH) of the hydrodynamic diameter (Size) by a method. Polymeric micelles prepared in Example 2 (2k-31-20.4% (Rutin / FPBA = 0.5), 2k-45-22.7% (Rutin / FPBA = 0.25), 2k-70- It is a figure which shows the time-dependent change (in PBS (pH7.4)) of the hydrodynamic diameter (Size) by the dynamic light scattering (DLS) method of 23.3% (Rutin / FPBA = 0.1)). 7A and 7B show the behavior of polymer micelles (2k-45-22.7% (Rutin / FPBA = 0.25)) in the presence of different concentrations of H ₂ O ₂ (1 mM and 0.1 mM), respectively. It is a figure which shows the time-dependent change of the hydrodynamic diameter (Size) and polydispersity (PdI) by a dynamic light scattering (DLS) method. H ₂ O ₂ in the absence (Figure 8A) or 1 mM _H 2 _{O 2} presence is a graph showing the time course of the absorption spectrum of rutin in (Fig. 8B). Polymer micelles (2k-45-22.7%) in the presence of 1 mM H ₂ O ₂ (FIG. 9A), in the presence of 0.1 mM H ₂ O ₂ (FIG. 9B) or in the absence of H ₂ O ₂ (FIG. 9C) It is a figure which shows a time-dependent change of the absorption spectrum of (Rutin / FPBA = 0.25)).

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.
In addition, this invention is not limited to the following embodiment, In the range which does not deviate from the summary, it can change arbitrarily and can implement. All publications and publications mentioned in this specification are herein incorporated by reference in their entirety regardless of their purpose.

1. Polymer Composite One aspect of the present invention provides a polymer composite. A polymer composite according to an embodiment is a block copolymer having a polymer segment having at least one boronic acid group selected from a phenylboronic acid group or a pyridylboronic acid group in a side chain, and a hydrophilic polymer segment And a low molecular weight drug including a binding site with the boronic acid group.

The present inventors can release a drug by cleaving a bond between a specific boronic acid group and a binding site of a boronic acid group in a drug (for example, a cis-diol structure) by oxidation with a reactive oxygen species (ROS). In particular, we succeeded in obtaining a polymer complex that can be used for the delivery of small molecule drugs.
Conventionally, a carrier for drug delivery using a polymer chain in which a phenylboronic acid group is introduced into a side chain has been proposed (for example, Patent Document 1: International Publication No. 2013/073697). These are intended for nucleic acids as drugs, and the drug release mechanism is also phenylboron utilizing exchange with adenosine triphosphate (ATP) present in high concentration in the intracellular environment or pH change (low pH). It depends on the cleavage of the acid ester structure. In the present invention, cleavage of the phenylboronic acid ester structure utilizing pH change (lowering the pH) and further drug release due to this may occur, but even when there is no pH change, the polymer side responding to ROS The elimination of boronic acid groups from the chain can be utilized during drug release. In Patent Document 1, since the nucleic acid is an anionic polymer, the polymer chain having a phenylboronic acid group is limited to a cationic chain. However, in the polymer complex containing the low molecular weight drug of the present invention (particularly, a hydrophobic low molecular weight compound), it is not limited to the cationic chain, and various polymer chains can be applied. Note that the present invention is not limited to the estimation mechanism. The present invention has a relatively high stability in the biological environment of the binding between a low molecular weight drug and a boronic acid group (hydrophobic interaction between boronic acid polymer segments to which the low molecular weight drug is bound) and a novel by ROS oxidation This is based on the discovery of the drug release mechanism.

The present inventors have also found that bond cleavage by ROS oxidation occurs depending on the ROS concentration. For example, responsiveness to ROS can be controlled by controlling the introduction rate of boronic acid groups. Therefore, based on the difference in the ROS concentration in the living environment, drug release at the target site and drug release can be controlled. For example, the bond between the fluorinated phenylboronic acid group and the 1,2-diol of rutin is stably maintained without being cleaved at about 0.04 mM or less, which corresponds to the H ₂ O ₂ concentration in blood, under high oxidative stress, such as in the brain of Alzheimer's patients cleavable in (high concentration H ₂ O ₂ of about 1mM or more). Such a drug delivery system based on a novel drug release mechanism based on a novel ROS oxidation, which is unconventional, is useful in terms of diversification of a delivery drug and a target tissue and drug release controllability.

The reactive oxygen species (ROS) is a general term for highly reactive oxygen species derived from oxygen molecules (O ₂ ). Specifically, superoxide anion radical (commonly referred to as superoxide; O ₂ ⁻ ), hydroxyl radical (.OH), hydrogen peroxide (H ₂ O ₂ ), singlet oxygen ( ¹ O ₂ ), nitric oxide (NO ), Nitrogen dioxide (ONO), ozone (O ₃ ), lipid peroxide (LOOH). In one embodiment, the reactive oxygen species (ROS) is hydrogen peroxide (H ₂ O ₂ ).

  In the present specification, the “polymer complex” refers to a structure in which a drug is supported in a polymer. The polymer complex can be used as a carrier (drug carrier) for drug delivery. As used herein, “for drug delivery” means biocompatible and capable of carrying the drug on a carrier.

  The polymer complex is, for example, a fine particle encapsulating a drug, and examples thereof include vesicles, dendrimers, hydrogels, and nanospheres.

“Vesicle” is intended to be a micelle, liposome, or hollow microparticle. The vesicle preferably has a biocompatible outer shell (shell portion), and the outer surface may be modified with a ligand if necessary.
“Micelle” means a vesicle formed by a single-layer molecular film. Examples of micelles include micelles formed from amphiphilic molecules such as surfactants, and micelles formed from polyion complexes (PIC micelles).
“Polyion complex” (hereinafter also referred to as “PIC”) is a copolymer of a hydrophilic block such as PEG and an anionic block, and a hydrophilic block such as PEG and a cationic block (for example, polyglutamic acid, polyasparagine). It is an ionic layer formed between the cationic block and the anionic block of both block copolymers by mixing a copolymer with an acid or the like) in an aqueous solution so as to neutralize the charge. The significance of binding PEG and the above-mentioned charged polymer chain is that the polyion complex is prevented from aggregating and precipitating, and thereby the polyion complex has a monodisperse core-shell structure with a particle size of several tens of nm. Forming nano-particles having In this case, since PEG covers the outer shell (shell) of the nanoparticle, it is known that it has high biocompatibility and is advantageous in improving the residence time in blood. It has also been shown that in forming a polyion complex, one charged block copolymer does not require a PEG moiety and may be replaced with a homopolymer, surfactant, nucleic acid and / or enzyme. In the formation of the polyion complex, at least one of the anionic polymer and the cationic polymer forms a copolymer with PEG, and both of them may form a copolymer with PEG. Further, it is well known that PIC micelles are easily formed when the PEG content is increased, and PICsomes are easily formed when the PEG content is reduced. The polyion complex is disclosed in, for example, JP-A-8-188541 and International Publication WO2006 / 118260.
The “polyion complex type polymersome” (hereinafter also referred to as “PICsome”) means hollow fine particles formed by the polyion complex.
“Liposome” means a vesicle formed by a bilayer molecular membrane. The molecular membrane is usually a bilayer membrane made of phospholipids.

The average particle diameter of the polymer composite of the embodiment is, for example, 400 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, or 80 nm or less, for example, 10 nm or more, 20 nm or more, 30 nm or more, or 40 nm or more. is there. The micellar structure has a diameter of, for example, 30 nm to 150 nm or, for example, 30 nm to 100 nm.
The polydispersity (PDI) of the polymer composite is, for example, 0.25 or less, preferably 0.20 or less, more preferably 0.15 or less.
In the present invention, the average particle diameter of the micellar structure refers to the hydrodynamic diameter (average particle diameter). The average particle diameter and polydispersity (PDI) are measured by a dynamic light scattering (DLS) method, and are values suitable for quality control purposes as an index of dispersion stability.

The polymer composite according to one embodiment of the present invention is a micellar structure containing a drug. Hereinafter, although the micellar structure shown in FIG. 1A will be described, the polymer composite of the present invention is not limited to such a form.
FIG. 1A shows a schematic diagram of a micellar structure (drug-containing polymer micelle 7) according to one embodiment. In FIG. 1A, (b) shows the drug-encapsulating polymer micelle 7, and (a) shows each component of the drug-encapsulating polymer micelle 7. As shown in FIGS. 1A (a) and (b), the drug-encapsulating polymer micelle 7 includes a block copolymer 5 and a low-molecular drug 6. The block copolymer 5 is composed of a polymer segment 1 and a hydrophilic polymer segment 3, and optionally a ligand 4 at the terminal. A micelle is formed by arranging the polymer segment 1 radially so that the polymer segment 1 is on the inside and the hydrophilic polymer segment 3 is on the outside, and the low-molecular drug 6 is encapsulated in the micelle.

  The polymer segment 1 of the block copolymer 5 has a boronic acid group 2 in the side chain, and the low molecular weight drug 6 has a binding site (not shown) with the boronic acid group. The acid group 2 and the boronic acid binding site form a covalent bond. For example, as shown in FIG. 1B, between a fluorinated phenylboronic acid group (FPBA), which is an example of a boronic acid group 2, and rutin having a 1,2-diol structure as a binding site of boronic acid. A covalent bond (phenylboronic acid ester structure) is formed. That is, in the drug-encapsulating polymer micelle 7, the low molecular drug 6 and the polymer segment 1 in the block copolymer 5 are covalently bonded to form a core part, and the other part in the polymer 5 (hydrophilic polymer) The segment 3 or the like is spread outward and forms a shell portion (outer shell portion). Since the drug-encapsulating polymer micelle 7 has the hydrophilic polymer segment 3 in the shell portion, it is excellent in biocompatibility (stability in blood).

  The bond structure between the boronic acid group 2 and the boronic acid binding site is cleaved by oxidation with reactive oxygen species (ROS). Since the boronate ester structure generated by cleavage is unstable, it is hydrolyzed to release a small molecule drug.

  In the embodiment shown in FIG. 1A, the block copolymer 5 constituting the drug-encapsulating polymer micelle 7 includes a block copolymer 5a having a ligand 4 at a terminal and a block copolymer 5b having no ligand 4 at a terminal, A drug-encapsulating polymer micelle 7 in which a part of the surface of the micelle is modified with the ligand 4 is formed. Ligand 4 can function to deliver the drug to the target site. In addition, the block copolymer 5 may be comprised only with the block copolymer 5b which does not have the ligand 4 at the terminal.

  Hereinafter, each component constituting the polymer composite will be described.

(1) Block Copolymer The block copolymer has a polymer segment having a boronic acid group in the side chain (hereinafter also simply referred to as “boronic acid segment”) and a hydrophilic polymer segment.

A Hydrophilic polymer segment The hydrophilic polymer segment may be constituted by any appropriate hydrophilic polymer. Examples of the hydrophilic polymer include poly (ethylene glycol), polysaccharide, poly (vinyl pyrrolidone), poly (vinyl alcohol), poly (acrylamide), poly (acrylic acid), poly (methacrylamide), and poly (methacrylic). Acid), poly (methacrylic acid ester), poly (acrylic acid ester), polyhydroxyethyl acrylate, poly (hydroxyethyl methacrylate), polyamino acid, poly (malic acid), poly (2-methyl-2-oxazoline) , Poly (2-ethyl-2-oxazoline), poly (2-isopropyl-2-oxazoline), or derivatives thereof. Specific examples of polysaccharides include starch, dextran, fructan, galactan and the like. Among these, poly (ethylene glycol) (PEG) is commercially available as terminal-reactive polyethylene glycols having various functional groups at the terminals, and those having various molecular weights are commercially available. Can be preferably used.

B Boronic acid segment B-1 Boronic acid group The boronic acid segment contains a boronic acid group in the side chain. The boronic acid group forms a bond with a boronic acid binding site contained in the low molecular drug, and as a result, a stable complex (for example, a micellar structure containing the low molecular drug) can be formed.
The boronic acid group is not limited as long as it is represented by R—B (OH) _2. Examples of the boronic acid group that can be used in vivo include a phenylboronic acid group and a pyridylboronic acid group. At least one hydrogen of phenyl or pyridyl of the phenylboronic acid or pyridylboronic acid group may be substituted with a substituent. That is, in the present specification, the term “phenylboronic acid” or “pyridylboronic acid group” includes those in which phenyl or pyridyl is substituted. The number of hydrogens to be substituted is 1, 2, 3, or 4, and when only one hydrogen is substituted, the substituent and the introduction site of B (OH) ₂ can be any of ortho, meta, and para. Good. By introducing a substituent, the pKa of the boronic acid group can be controlled. The pKa of the boronic acid group is specified from the boronic acid group-containing polymer chain synthesized as a monomer.

  In one embodiment, the boronic acid group has at least one of phenyl or pyridyl of the boronic acid group so as to have a pKa near physiological pH from the viewpoint of adapting to a biological environment typified by blood (less than pH 7.5). One hydrogen is replaced by an optional substituent. The pKa of the boronic acid group is preferably less than 8, and more preferably less than 7.5. On the other hand, the lower limit of pKa of the boronic acid group is not particularly limited, but may be 2 or more, or 3 or more, for example.

Use of a substituted boronic acid group has the following advantages.
First, the increased hydrophobicity of the boronic acid segment results in a favorable interaction between the block copolymers in an aqueous medium, resulting in enhanced association between the polymers, so that the block copolymers of the present invention are A very stable micellar structure can be formed in an aqueous medium. Examples of the aqueous medium include aqueous buffers such as water, physiological saline, phosphate buffer, carbonate buffer, borate buffer, and acetate buffer. In particular, since the substituted boronic acid group is highly hydrophobized under a pH environment of pKa or lower, the micellar structure can be stabilized by appropriately controlling pKa.
Second, by increasing the hydrophobicity of the boronic acid segment, when the small molecule drug is a hydrophobic substance, the boronic acid segment between the boronic acid binding site (eg, 1,2-diol) of the low molecule drug and the block copolymer Hydrophobic interactions can be enhanced. As a result, extremely stable complexes with these molecules can be obtained.
Third, the pKa of phenylboronic acid is usually about 8 to 9, but the pKa can be appropriately controlled by substitution. Since the boronic acid group and the boronic acid binding site bind to each other under a pH environment of pKa or higher, for example, the pKa is preferably close to or below physiological pH (preferably less than 8, more preferably 7.5). By performing substitution (so as to show a lower pKa), the above binding ability can be suitably exerted in a living environment.

In one embodiment, the boronic acid group is selected from a phenylboronic acid group (PBA) represented by the following formula (b1) or a pyridylboronic acid group represented by the following formula (b2).
(In the above formula,
R _b represents halogen selected from fluorine, chlorine, bromine, or iodine, or nitro;
n is an integer from 0 to 4,
* Indicates the point of attachment to the polymer chain)

Among these, from the viewpoint of reducing pKa, the boronic acid group is a fluorinated phenylboronic acid group in which R _b is fluorine in the above formula (b1) (that is, a group of the following formula (b11); hereinafter referred to as “FPBA group”. Or a pyridylboronic acid group in which n is 0 in the formula (b2) (that is, a group of the following formula (b21)), more preferably a fluorine represented by the following formula (b11) A phenylboronic acid group (FPBA group).
(In the above formula,
n is an integer of 1 to 4,
* Indicates the point of attachment to the polymer chain)

  In a preferred embodiment, the boronic acid group is a group of the above formula (b11), and the boronic acid group is introduced into the side chain of the polyamino acid via a carbamoyl bond (—CONH—). In such a case, the pKa of the boronic acid can be lowered to about 7.2.

The number of boronic acid groups introduced into the block copolymer of the embodiment can be appropriately adjusted depending on the type of polymer chain constituting the boronic acid segment (for example, the type or number of amino acid residues). Specifically, as long as a micellar structure can be stably formed, the number or introduction rate of boronic acid groups can be set to any appropriate value. As an example, the introduction rate of boronic acid groups (BA; phenylboronic acid group or pyridylboronic acid group) to the block copolymer, that is, the ratio of the molecular weight of the boronic acid group (BA) to the molecular weight of the block copolymer (BA introduction rate) is It is preferably 10 to 40%, more preferably 10 to 30%, further preferably 12 to 35%, and particularly preferably 20 to 25% from the viewpoint of micelle stability.
The BA molecular weight is the molecular weight of a boronic acid group (for example, a phenylboronic acid group (PBA) represented by the formula (b1) or a pyridylboronic acid group represented by the following formula (b2)) present in the block copolymer. It is the sum.
The total number of boronic acid groups contained in the block copolymer is, for example, 1 or more, preferably 5 to 50, more preferably 10 to 40.

B-2 Polymer Segment The polymer chain constituting the polymer segment constituting the boronic acid segment is not particularly limited as long as it can introduce a boronic acid group into the side chain and can carry a low molecular drug.
In one embodiment, the polymer segment is composed of a polyamino acid, and a boronic acid group is introduced into the side chain of the polyamino acid. Examples of polyamino acids include nonpolar amino acids such as leucine, isoleucine, phenylalanine, methionine, and tryptophan; acidic amino acids such as aspartic acid and glutamic acid; basic amino acids such as lysine, ornithine, arginine, homoarginine, and histidine; and derivatives thereof; And polymers of amino acids selected from these combinations.

The boronic acid group is typically introduced into the side chain of the polyamino acid via a linking group. Examples of the linking group include amide bond, carbamoyl bond, alkyl bond, ether bond, ester bond, thioester bond, thioether bond, sulfonamide bond, urethane bond, sulfonyl bond, thymine bond, urea bond, thiourea bond, and these. Combinations are listed. The linking group may include any suitable spacer between these bonds. Examples of the spacer include a linear or branched alkylene group having 1 to 27 carbon atoms, preferably 2 to 5 carbon atoms, a short ethylene glycol chain (—OCH ₂ CH ₂ —) _{n, and the} like.
In one embodiment, the boronic acid group is introduced into the side chain of the polyamino acid via a carbamoyl bond (—CONH—). In such a case, the pKa of the boronic acid group can be reduced, and the binding ability between the boronic acid group and the boronic acid binding site in the drug can be exhibited in a biological environment.

In one embodiment, the boronic acid polymer segment can be a charged polymer segment (eg, an anionic polymer chain segment or a cationic polymer chain segment) and / or a hydrophobic polymer segment. In such a case, in the aqueous medium, the core part composed of the charged polymer segment and / or the hydrophobic polymer segment in which the low molecular weight drug is supported via the covalent bond is changed to the shell part composed of the hydrophilic polymer segment. A covered micellar structure can be formed.
Note that a composite such as PIC may be suitably formed by combining a block copolymer containing a charged polymer segment and a polymer having a charge opposite to each other.

  The cationic polymer segment can be constituted by any suitable cationic polymer. Typical examples of the cationic polymer include polyamino acids having a cationic group in the side chain. As the cationic group, an amino group is preferable. By having an amino group in the side chain, the amino group can be coordinated to boron in the boronic acid group in an aqueous medium, and can contribute to stabilization of the polymer composite (for example, a micellar structure).

Examples of the amino acid from which the amino acid residue constituting the polyamino acid having a cationic group in the side chain is derived include any suitable amine compound for basic amino acids such as lysine, ornithine, arginine, homoarginine, histidine, and acidic amino acids. And amino acid derivatives into which is introduced. Of these, amino acid derivatives in which the carboxyl group (—C (═O) OH) of lysine and acidic amino acid is substituted with any group of the following formulas (i) to (iv) are preferable, and lysine and asparagine The —OH part of the α-position or β-position of the acid or the α-position or γ-position of the glutamic acid (—C (═O) OH) was substituted with any group of the following formulas (i) to (iv) An amino acid derivative is more preferable, and the —OH part of the α-position or β-position of lysine and aspartic acid or the α-position or γ-position of glutamic acid (—C (═O) OH) is substituted with a group of the following formula (i) The amino acid derivatives obtained are more preferred.
—NH— (CH ₂ ) _p1 — [NH— (CH ₂ ) _q1 —] _r1 NH ₂ (i);
-NH- _{(CH 2)} p2 -N _{[- (CH 2)} q2 -NH _{2] 2} (ii);
-NH- _{(CH 2)} p3 -N _{{[- (CH 2)} q3 -NH _{2] [- (CH} 2) q4 -NH-] _r2 H} (iii); and -NH- _{(CH 2) p4} - _{N {- (CH 2) q5} -N _{[- (CH 2)} q6 -NH _{2] 2} 2} (iv)
(In formulas (i) to (iv), p1 to p4, q1 to q6, and r1 to r2 are each independently an integer of 1 to 5).

  In the above formulas (i) to (iv), p1 to p4 and q1 to q6 are independently of each other, preferably 2 or 3, more preferably 2. Moreover, r1-r2 is mutually independently, Preferably it is an integer of 1-3.

  When the cationic amino acid residue is a lysine residue, there is an advantage that a polyamino acid chain is easily synthesized and the obtained block copolymer is very excellent in biocompatibility. The cationic amino acid residue is an amino acid residue in which the —OH part of the carboxyl group (—C (═O) OH) of the acidic amino acid is substituted with any group of the above formulas (i) to (iv). In some cases, these residues have different amine functional groups, so pKa exhibits multiple steps, and at physiological conditions of pH 7.4, the multiple amine functional groups are partially protonated, It has been shown that damage to cells is low.

  In one embodiment, the charged polymer segment preferably has a charge opposite to that of the small molecule drug. For example, when the low molecular drug has a positive charge in an aqueous medium, the charged polymer segment is preferably an anionic polymer chain segment. On the other hand, when the low molecular drug has a negative charge in an aqueous medium, the charged polymer segment is preferably a cationic polymer chain segment. A low molecular drug having opposite charges and a high molecular segment are bonded by electrostatic interaction, whereby a micellar structure is formed such that the low molecular drug and the charged high molecular segment are inside. The effect that a very stable micellar structure can be formed in an aqueous medium (preferably an aqueous medium near neutrality) can be obtained.

As the amino acid residue into which the boronic acid group is introduced, any appropriate amino acid residue can be selected as long as the boronic acid group can be introduced through the linking group. From the viewpoint of ease of synthesis, the boronic acid group is preferably introduced into a cationic amino acid residue having an amino group in the side chain. Only one boronic acid group may be introduced into the side chain, or a plurality of boronic acid groups may be introduced.
As a specific example, a boronic acid group is a carboxyphenylboronic acid or an ester thereof in which at least one hydrogen of the amino group and phenyl ring is substituted on a cationic amino acid residue having an amino group in the side chain. It can be introduced via an amide bond generated by the reaction of
As another specific example, a boronic acid group is introduced into the amino group of a cationic amino acid residue having an amino group in the above side chain through a linking group consisting of two amide bonds and a propylene group contained therebetween. Can be done.

  In addition to the cationic amino acid residue and the boronic acid group-containing amino acid residue, the polyamino acid chain may be referred to as an amino acid residue having a hydrophobic group in the side chain (hereinafter referred to as “hydrophobic amino acid residue”). ). By including the hydrophobic amino acid residue, the hydrophobic interaction acting between the boronic acid segments is increased in the aqueous medium, and as a result, a more stable micellar structure can be formed.

Examples of the amino acid from which the hydrophobic amino acid residue is derived include non-polar natural amino acids such as leucine, isoleucine, phenylalanine, methionine, and tryptophan, and amino acids having a hydrophobic group introduced in the side chain. Of the hydrophobic derivatives. Hydrophobic derivatives of such amino acids are preferably acidic amino acid side chains such as aspartic acid and glutamic acid, acidic amino acid side chains into which amine compounds have been introduced, and basic such as lysine, ornithine, arginine, homoarginine, and histidine. Derivatives in which a hydrophobic group is introduced into the side chain of an amino acid can be mentioned.
In the present specification, “hydrophobic” means that the solubility in 100 g of water at 25 ° C. is preferably 5 g or less, more preferably 4 g or less.

  Examples of the hydrophobic group to be introduced include saturated or unsaturated linear or branched aliphatic hydrocarbon groups having 6 to 27 carbon atoms, aromatic hydrocarbon groups having 6 to 27 carbon atoms, or steryl groups (steroids). (Residues derived from) can be preferably exemplified.

  Examples of the saturated linear or branched aliphatic hydrocarbon group having 6 to 27 carbon atoms include hexyl group (for example, n-hexyl group), heptyl group, octyl group, nonyl group, decyl group, undecyl group. Group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, icosyl group, eicosyl group, heicosyl group, heneicosyl group, docosyl group, tricosyl group, tetracosyl group, pentacosyl group, Examples include a hexacosyl group and a heptacosyl group. Examples of the unsaturated linear or branched aliphatic hydrocarbon group having 6 to 27 carbon atoms include, for example, 1 to 5 carbon-carbon bonds in the chain of the alkyl group exemplified above are carbon atoms. -The group which is a carbon double bond is mentioned.

  Examples of the aromatic hydrocarbon group having 6 to 27 carbon atoms include an aryl group and an aralkyl group. Specific examples of these include phenyl group, naphthyl group, tolyl group, xylyl group, benzyl group, phenethyl group and the like.

The steroid from which the steryl group is derived is, for example, sterol or a derivative thereof. For example, natural sterols include, but are not limited to, cholesterol, cholestanol, dihydrocholesterol, cholic acid, campesterol, cystosterol, and the like, and these semi-synthetic or synthetic compounds include these natural products. For example, synthetic precursors (if necessary, certain functional groups, some or all of the hydroxy groups are protected by hydroxy protecting groups known in the art, or the carboxyl groups are carboxyl protected Including compounds protected by groups). In addition, the sterol derivative means that a C _1-12 alkyl group and a halogen atom such as chlorine, bromine, and fluorine are introduced into the cyclopentanone hydrophenanthrene ring within a range that does not adversely affect the object of the present invention. It means that the ring system can be saturated, partially unsaturated, and the like. The sterol from which the steryl group can be derived is preferably a sterol derived from animal or vegetable oils such as cholesterol, cholestanol, dihydrocholesterol, cholic acid, campesterol, cystosterol, and more preferably cholesterol, cholestanol, dihydroxycholesterol. And particularly preferred is cholesterol.

  The polyamino acid chain segment may contain only one type of amino acid residue or two or more types of amino acid residues as a cationic amino acid residue, a boronic acid group-containing amino acid residue, and a hydrophobic amino acid residue. Good. The order of binding of the cationic amino acid residue, boronic acid group-containing amino acid residue and hydrophobic amino acid residue in the polyamino acid chain segment is arbitrary, and may be a random structure or a block structure.

  The number of cationic amino acid residues, boronic acid group-containing amino acid residues, and hydrophobic amino acid residues contained in the polyamino acid chain segment can be appropriately adjusted depending on the type of each amino acid residue.

  For example, the total number of amino acid residues contained in the polyamino acid chain segment is preferably an integer of 10 or more, more preferably an integer of 20 or more (for example, an integer of 30 or more, 40 or more, or 50 or more), preferably 300 or less. More preferably, it is an integer of 200 or less, more preferably 150 or less, and still more preferably 100 or less. When the polyamino acid chain segment includes a hydrophobic amino acid residue, the number of cationic amino acid residues can be appropriately adjusted from the above preferred range depending on the number of hydrophobic amino acid residues. When the polyamino acid chain segment includes a hydrophobic amino acid residue, the micelle can be more stabilized. Therefore, the total number of cationic amino acid residues, boronic acid group-containing amino acid residues, and hydrophobic amino acid residues is preferably 10 It may be an integer of ~ 150, more preferably 20-100.

  The anionic polymer segment can be constituted by any suitable anionic polymer. Representative examples of the anionic polymer include polyamino acids having an anionic group in the side chain. Examples of the anionic group include a carboxyl group. Examples thereof include those derived from an anionic polymer selected from the group consisting of poly (glutamic acid), poly (aspartic acid), poly (acrylic acid), poly (methacrylic acid), and poly (malic acid). Or the polyamino acid comprised from the amino acid derivative by which anionic groups, such as a carboxy group, were introduce | transduced into the side chain of the amino acid may be sufficient.

  The introduction of a boronic acid group into the side chain of the anionic polymer segment is also preferably introduced via a linking group in the same manner as the above cationic polymer segment. The number of boronic acid groups introduced into the side chain may be one or plural. In addition to the anionic amino acid residue and the boronic acid group-containing amino acid residue, the polyamino acid chain may further include an amino acid residue having a hydrophobic group in the side chain (hydrophobic amino acid residue).

  The hydrophobic polymer segment can be constituted by any suitable hydrophobic polymer. Typical examples of the hydrophobic polymer include polystyrene. The introduction of the boronic acid group into the side chain of the hydrophobic polymer segment is also preferably introduced via a linking group in the same manner as the above cationic polymer segment. When the boronic acid segment is composed of a hydrophobic polymer segment, hydrophobic interaction between the boronic acid polymer segments works favorably in an aqueous medium, resulting in enhanced association force between the polymers and stable stability. A micellar structure can be formed.

  Specific examples of C block copolymer

Specific examples of the block copolymer (cationic block copolymer) are shown in the formula (1) or (2). In the block copolymer of the formula (1) or (2), the boronic acid group is introduced into the side chain of the cationic amino acid residue. Typically, boronic acid groups can be introduced by reacting with the Q ₁ moiety of the block copolymer of formula (1) or (2), or the R ^6a and / or R ^6b moiety.

(In the formula (1) or (2),
R ¹ is a hydrogen atom or an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms,
R ² is a hydrogen atom, an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms, or an unsubstituted or substituted linear or branched alkyl group having 1 to 24 carbon atoms. An alkylcarbonyl group,
R ³ is a hydroxyl group, an unsubstituted or substituted linear or branched alkyloxy group having 1 to 12 carbon atoms, an unsubstituted or substituted linear or branched group having 2 to 12 carbon atoms. An alkenyloxy group, an unsubstituted or substituted linear or branched alkynyloxy group having 2 to 12 carbon atoms, or an unsubstituted or substituted linear or branched alkyl-substituted imino group having 1 to 12 carbon atoms Group,
The groups of R ^4a , R ^4b , R ^5a and R ^5b are, independently of one another, a methylene group or an ethylene group;
The groups R ^6a and R ^6b are independently selected from the groups (i) to (iv) above;
R ^6c and R ^6d are independently of each other an amino group of a group selected from the groups (i) to (iv) above, a saturated or unsaturated linear or branched group having 6 to 27 carbon atoms A group into which an aliphatic hydrocarbon group in the form of an aromatic hydrocarbon group having 6 to 27 carbon atoms or a steryl group is introduced,
The groups of R ^7a and R ^7b are, independently of one another, —O— or —NH—;
R ^8a and R ^8b are each independently a saturated or unsaturated linear or branched aliphatic hydrocarbon group having 6 to 27 carbon atoms or an aromatic hydrocarbon group having 6 to 27 carbon atoms. Or a steryl group,
The group of Q ₁ is —NH ₂ , —NHC (═NH) NH ₂ , or a group represented by the following formula (II):
The group of Q ₂ is —NH ₂ , —NHC (═NH) NH ₂ , or an amino group of the group represented by the above formula (II), a saturated or unsaturated linear or branched group having 6 to 27 carbon atoms A group into which an aliphatic hydrocarbon group in the form of an aromatic hydrocarbon group having 6 to 27 carbon atoms or a steryl group is introduced,
The group of P is the side chain of leucine, isoleucine, phenylalanine, methionine or tryptophan;
L ¹ and L ³ are, independently of each other, —S—S— or a valence bond;
L ² is —NH—, —O—, —O (CH ₂ ) _p1 —NH—, or —L ^2a — (CH ₂ ) _q1 -L ^2b —, wherein p1 and q1 are Independently, an integer from 1 to 5, L ^2a is OCO, OCONH, NHCO, NHCOO, NHCONH, CONH or COO, L ^2b is NH or O,
L ⁴ _{represents, -OCO- (CH 2) p2 -CO} -, - NHCO- (CH 2) p3 -CO-, or ^-L 4a _{- (CH} 2) a q2 -CO-, wherein, p2, p3 , And q2, independently of one another, are integers from 1 to 5, L ^4a is OCONH, —CH ₂ NHCO—, NHCOO, NHCONH, CONH or COO;
k is an integer of 5 to 20,000,
s is an integer of 1 to 6,
m is an integer from 0 to 300;
n is an integer of 0 to m,
a is an integer of 0 to 300;
b is an integer of 0 to a;
v is an integer from 0 to 300;
c is an integer from 0 to 300;
x is an integer of 0 to 300, y is an integer of 0 to x, z is an integer of 0 to 300,
Where z is an integer greater than or equal to 2 when m is 0;
m is an integer greater than or equal to 1 when z is 0;
Total number of primary amino groups and secondary amino groups contained in z Q ₁ groups, and (amino) primary amino groups contained in (mn) R ^6a groups and n R ^6b groups An organic group in which the hydrogen atom of the amino group of 1 or more and less than w has a boronic acid group (for example, an FPBA group represented by the above formula (I)), where w is the total of the total number of groups and secondary amino groups (Eg, an acyl group). )

In the above formula (1) or (2), the combination of L ¹ and L ^{2 and} the combination of L ³ and L ⁴ need to be combined so that they can be combined into one linking group. For example, when L ² is —NH—, L ¹ is not —S—S— but a valence bond.

  In the above formula (1) or (2), k representing the repeating number of ethylene glycol (or oxyethylene) is an integer of 5 to 20,000, preferably 5 to 2,000, more preferably 5 to 1,500. It is.

Examples of the alkyl moiety of the linear or branched alkyloxy group having 1 to 12 carbon atoms, the alkyl-substituted imino group, and the alkyl group defined by the groups R ^{1 to} R ³ include, for example, a methyl group and an ethyl group , N-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, decyl group, and undecyl group. The alkenyl or alkynyl moiety in the straight-chain or branched alkenyloxy group having 2 to 12 carbon atoms or the straight-chain or branched alkynyloxy group having 2 to 12 carbon atoms is as defined above having 2 or more carbon atoms. The thing which contains a double bond or a triple bond in the illustrated alkyl group can be mentioned.

For such groups or moieties, the substituents when “substituted” include, but are not limited to, C _1-6 alkoxy groups, aryloxy groups, aryl C _1-3 oxy groups, cyano groups, carboxyls A group, an amino group, a C _1-6 alkoxycarbonyl group, a C _2-7 acylamide group, a tri-C _1-6 alkylsiloxy group, a siloxy group, a silylamino group, or an acetalized formyl group, formyl group, chlorine or Mention may be made of halogen atoms such as fluorine. Here, for example, the indication of C _1-6 means 1 to 6 carbon atoms, and hereinafter used to represent the same meaning. Further, the unsubstituted or substituted linear or branched alkylcarbonyl group having 1 to 12 carbon atoms in the unsubstituted or substituted linear or branched alkylcarbonyl group having 1 to 24 carbon atoms is as described above. Examples of the alkyl moiety having 13 or more carbon atoms include a tridecyl group, a tetradecyl group, a pentadecyl group, a nonadecyl group, a docosanyl group, and a tetracosyl group.

The groups of the above formulas (i) to (iv) and the hydrocarbon group or steryl group defined in the above formula (1) or (2) are as described above. Regarding the groups of Q ₁ , Q ₂ , R ^6a , R ^6b , R ^6c , R ^6d , R ^8a and R ^8b , the same group may be selected for all the repeating units to which they belong, or different groups may be selected. Good. Moreover, s is 1, 3, or 4, for example.

The hydrophobic group introduced into the group of Q ₂ , R ^6c or R ^6d may be introduced via any appropriate linking group. Specific examples of the linking group include those described above as the linking group applicable when introducing a boronic acid group.

In the formula (1) or (2), when both groups of R ^4a and R ^4b represent an ethylene group, typically n and b are the integer 0, or mn and a- It represents a polyamino acid in which b is an integer 0. The former represents, for example, poly-α-glutamic acid obtained by polymerization of N-carboxylic acid anhydride of glutamic acid γ-benzyl ester, and the latter is, for example, a strain belonging to the genus Bacillus including Bacillus natto. It represents poly-γ-glutamic acid to be produced. On the other hand, when both groups of R ^4a and R ^4b represent methylene groups, it is understood that the respective repeating units having these groups can coexist. The same applies to the groups R ^5a and R ^5b in formula (1) or (2). From the viewpoint of production efficiency, the groups R ^4a and R ^4b are preferably methylene groups, and the groups R ^5a and R ^5b are ethylene groups.

In another embodiment, the group R ¹ may be substituted with a group that includes a target binding site. By introducing the target binding site to the end of the polymer, the reachability of the drug (for example, nucleic acid) to the desired target site can be improved. The group containing the target binding site may be any suitable group as long as it has directivity or functionality for the target tissue, for example, an antibody or a fragment thereof, or other functionality or targeting property It may be a group derived from a physiologically active substance such as protein, peptide, aptamer, sugar such as lactose, folic acid, and derivatives thereof.

In one embodiment, the group R ¹ can be a ligand. By introducing the ligand into the end of the polymer, a polymer complex (eg, a micellar structure) in which at least a part of the surface is modified with the ligand can be formed. The ligand can improve the reachability of the drug to a desired target site.
For example, the ligand can be glucose or a derivative GLUT1 ligand of glucose that binds to GLUT1. In this case, glucose or a derivative thereof exposed on the outer surface binds to GLUT1, which is a glucose transporter expressed on the inner surface of the vascular endothelial cell of the brain, whereby the polymer complex is taken into the vascular endothelial cell, and blood It may be possible to move through the brain barrier (BBB) to the brain parenchyma. For example, R ¹ can have the following structure:

  In another embodiment, the block copolymer is preferably biodegradable. Various copolymers are known as such copolymers, and any of them can be used in principle. For example, highly biocompatible and biodegradable block copolymers include, for example, polyethylene glycol-polyaspartic acid, polyethylene glycol-polyglutamic acid, and polyethylene glycol-poly ((5-aminopentyl) -aspartic acid. ) Block copolymers can be used, and polymers in which the above boronic acid is introduced into the side chain of the polyamino acid chain of these polymers are also preferred.

In a preferred embodiment, the block copolymer is represented by the following formula (3).
In Formula (3), R ^9a is a divalent group represented by —NH— (CH ₂ ) _{p 2} — [NH— (CH ₂ ) _{q 2} —] _r 2 NH—, and p 2, q 2, and r 2 are Each is independently an integer of 1 to 5. Preferably, p2, q2, and r2 are each independently an integer of 1 to 3.
In Formula (3), R ^9b is —NH— (CH ₂ ) _p3 — [NH— (CH ₂ ) _q3 —] _r3 NH ₂ , and p3, q3, and r3 are each independently of each other, It is an integer of 1-5. Preferably, p3, q3, and r3 are each independently an integer of 1 to 3.
In formula (3), BA represents a boronic acid group. Specifically, it is a phenylboronic acid group (PBA) represented by the above formula (b1) or (b11) or a pyridylboronic acid group represented by the above formula (b2) or (b21).
In formula (3), x is 0.1-0.9.
In formula (3), m is an integer of 1-300.
In the formula (3), R ¹ , R ² , L ¹ , L ² , R ^4a and k are the same as defined in the above formulas (1) and (2).
For example, when used for drug delivery to the brain, k is preferably an integer from 5 to 100.

Preferably, x is 0.1 to 0.9.
M is an integer of 1 to 300.
As x and m increase, the cationic amino group (NH ₂ ) present at the end of R ^9b increases, so that generally the charge repulsion of the micelle core part (boronic acid segment) increases and the stability of the micelle decreases. There is a tendency. Moreover, as x increases, the hydrophobicity of the micelle core part (boronic acid segment) increases, and the micelle stability tends to be improved.

  The block copolymer can be prepared by any suitable synthetic method. For example, an example of a method for producing a cationic block copolymer is disclosed in, for example, International Publication WO2015 / 170757, and a person skilled in the art will refer to the production method and modify it to produce a desired block copolymer. can do.

(2) Low molecular drug The low molecular drug used in the present invention is not particularly limited as long as it is a low molecular compound containing a binding site capable of forming a bond with a boronic acid group (hereinafter also referred to as “BA binding site”). The molecular weight is preferably, for example, 2,000 or less, 1,000 or less, 800 or less, or 500 or less. The lower limit of the molecular weight is not particularly limited. The low molecular weight drug of the present invention does not contain a high molecular compound such as a biopolymer such as a nucleic acid or an antibody.

  As the BA binding site, any appropriate chemical structure capable of forming a bond with a boronic acid group can be adopted. Examples of the chemical structure that can constitute the BA binding site include a polyol (particularly cis-diol) structure, a diamine structure, a hydroxyamine structure, a hydroxamic acid structure, an alkoxycarboxyamide structure, and a diphosphate structure. The reaction between the BA binding site and the boronic acid group is typically a dehydration reaction, and thus the binding between the BA binding site and the boronic acid group is typically a covalent bond. Examples of the compound having a chemical structure that can serve as a BA binding site include compounds having the following structures 2 to 44 in part and derivatives thereof.

When the boronic acid group is a phenylboronic acid group, the low molecular weight drug preferably includes any one of the chemical structures 2 to 43 described above.
In one embodiment, the small molecule drug comprises a 1,2-diol structure. That is, it is preferable that the low molecular weight drug includes any one of the chemical structures described above. All of these have a diol structure, and a stable bond can be formed with the phenylboronic acid group. More preferably, the low molecular weight drug preferably contains the 22 catechol structures. Catechol has a high binding constant with boronic acid because the diol group is fixed in the plane. For this reason, a low molecular drug having a catechol structure can form a more stable covalent bond with a boronic acid group in a biological environment.

In addition, when the boronic acid group is a pyridylboronic acid group, it is preferably a diphosphate structure (for example, the chemical structure of 44 above). It is known that a pyridylboronic acid group and a diphosphate structure form a covalent bond at pH 6 or less (Sanjoh et al, Org. Lett. 17, 2015, 588-591).

  In one embodiment, the small molecule drug is a hydrophobic substance. When the low molecular weight drug is a hydrophobic substance, a hydrophobic interaction acts between the boronic acid polymer segments to which the low molecular weight drug is bound, so that a more stable micellar structure can be formed.

  In one embodiment, the ratio of small molecule drug to boronic acid group (drug / BA ratio) is 0.05-1. Preferably, it is 0.1-0.5. By controlling the ratio between the low molecular weight drug and the boronic acid group (drug / BA ratio), a micellar structure excellent in stability and drug retention can be formed. The drug / BA ratio is the ratio of the total number of drugs to the total number of boronic acid groups contained in the polymer complex (number of moles of drug / number of moles of boronic acid group).

  Examples of the low molecular weight drug include various drugs, and examples include synthetic compounds, physiologically active substances, biocompatible fluorescent dyes, and contrast agents such as ultrasound, MRI and CT contrast agents.

  As will be described later, the polymer complex of one embodiment of the present invention is suitable for drug delivery to the brain, and can deliver the drug to the brain with high selectivity. Accordingly, the drug is not particularly limited. For example, a physiologically active substance that enhances the physiological function of the brain, a physiologically active substance that can treat brain diseases, a biocompatible fluorescent dye that can stain the brain, and ultrasound, MRI And contrast agents such as CT contrast agents can be used.

  In one embodiment, the small molecule drug is a therapeutic agent for a disease in which reactive oxygen species are directly or indirectly involved. As described above, since the polymer complex of the embodiment is one in which the drug is released by oxidation with the reactive oxygen species, that is, in the presence of the reactive oxygen species, the reactive oxygen species is directly or indirectly. Excellent therapeutic effects are expected for diseases related to the disease. For example, in the case of an antioxidant, the reactive oxygen species can be removed by the released drug.

An example of a low molecular drug having a boronic acid binding site is given below. The following compounds contain a catechol structure and are hydrophobic substances with low water solubility.

2. Method for producing polymer composite The polymer composite can be formed by a known method using the block copolymer. For example, a solution in which a low molecular drug is dissolved in a solvent such as alcohol and a solution in which a block copolymer is dissolved in a pH buffer solution are prepared separately, and then the two solutions are mixed and dialyzed against PBS. Thus, a polymer composite of a low molecular drug and a block copolymer (for example, a micellar structure containing a low molecular drug) can be produced. In the case of PIC micelles and liposomes, the drug is encapsulated in PIC micelles or liposomes by preparing a mixed solution of a polymer solution that forms PIC micelles or liposomes and stirring and mixing them. Alternatively, after the block copolymer solution is stirred to form a micellar structure or PIC micelle, a drug-dissolved solution can be added to the micelle solution to encapsulate the drug in the micelle.

3. Drug Delivery Device One aspect of the present invention provides a drug delivery device comprising the above-described polymer complex or a composition containing the polymer complex. The drug delivery device of the present invention can be used as a means for selectively and efficiently introducing an encapsulated desired drug into a target tissue. Another embodiment provides a method for releasing a desired drug contained in a target tissue or a method for controlling the release.
Specifically, the polymer complex is incorporated into various tissues in the body by administering a solution containing a polymer complex encapsulating a desired low molecular drug to a test animal.
The drug delivery device of the embodiment is one in which the drug is released by oxidation with reactive oxygen species, that is, in the presence of reactive oxygen species. Further, in one embodiment, drug release is dependent on the concentration of reactive oxygen species. Therefore, it is possible to selectively release a drug in a tissue having a high concentration of reactive oxygen species.
One embodiment is a method of releasing a drug at a target site based on the difference in ROS concentration. For example, at about 0.04 mM, which corresponds to the H ₂ O ₂ concentration in blood, the drug is stably retained in the polymer complex, under a high ROS concentration (under high oxidative stress; for example, a high concentration of H ₂ O ₂ The drug can be released at about 1 mM or more).

  The drug delivery device of the present invention can be applied to various animals such as humans, mice, rats, rabbits, pigs, dogs, cats and the like, but is not limited thereto. As the administration method to test animals, parenteral methods such as intravenous infusion are usually adopted, and each condition such as dose, number of administrations and administration period can be appropriately set according to the type and condition of the test animal. it can.

  The drug delivery device of the present invention can be used for treatment for introducing a desired low-molecular-weight drug into tissues that cause various diseases. Therefore, the present invention can also provide a pharmaceutical composition containing the above-described polymer complex and a method for treating various diseases using the above-described polymer complex (drug delivery device).

  For the above pharmaceutical compositions, excipients, fillers, extenders, binders, wetting agents, disintegrants, lubricants, surfactants, dispersants, buffers, preservatives, solubilizers commonly used in drug production. An agent, an antiseptic, a flavoring agent, a soothing agent, a stabilizer, an isotonic agent and the like can be appropriately selected and used, and can be prepared by a conventional method. Moreover, the form of a pharmaceutical composition normally employs an intravenous injection (including infusion), and is provided, for example, in the state of a unit dose ampoule or a multi-dose container.

  The above-mentioned pharmaceutical composition and treatment method are effectively applied to diseases in which reactive oxygen species are directly or indirectly involved among various diseases.

4). Delivery to Brain The drug delivery device of the present invention is particularly suitable for drug delivery to the brain. As described above, by modifying at least a part of the surface of the micellar structure with glucose or a glucose derivative that binds to GLUT1 (GLUT1 ligand), the glucose or its derivative exposed on the outer surface is converted to the vascular endothelial cells of the brain. It binds to GLUT1, which is a glucose transporter expressed on the inner surface of blood vessels, whereby the polymer complex can be taken up by vascular endothelial cells and can pass through the blood-brain barrier (BBB) and enter the brain parenchyma. .

  As used herein, “GLUT1 ligand” means a substance that specifically binds to GLUT1. Various ligands are known as GLUT1 ligands, including, but not limited to, molecules such as glucose and hexose, both of which are used in the present invention for the preparation of carriers or conjugates instead of glucose. be able to. The GLUT1 ligand preferably has an affinity for GLUT1 that is equal to or greater than that of glucose. 2-N-4- (1-azi-2,2,2-trifluoroethyl) benzoyl-1,3-bis (D-mannose-4-yloxy) -2-propylamine (ATB-BMPA), 6- (N- (7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino) -2-deoxyglucose (6-NBDG), 4,6-O-ethylidene-α-D-glucose, 2 -Deoxy-D-glucose and 3-O-methylglucose are also known to bind to GLUT1, and these molecules can also be used in the present invention as GLUT1 ligands.

  A block copolymer modified with glucose or a derivative of glucose binding to GLUT1 with a GLUT1 ligand and a method for producing a drug transporter using the same are described in International Publication No. 2015/075942, and the disclosure can be referred to. In this document, GLUT1 is expressed in an order of magnitude in vascular endothelial cells that construct the BBB, and the localization location changes depending on the blood glucose level (low blood glucose level: vascular side, high blood glucose level: brain parenchyma A technique for delivering a drug to the brain using the above has been proposed.

It is said that the brain consumes 20 to 25% of oxygen throughout the body, and it is known that the active oxygen species generated mainly in the process of metabolizing oxygen cause damage to living tissues (oxidative stress). It was also reported that oxidative modification products such as nucleic acids were detected from cerebrospinal fluid and that Aβ oligomers induced oxidative stress, suggesting that oxidative stress is a major factor in Alzheimer's disease (A. Nunomura , et al., J Neuropathol Exp Neurol 65, 631-641, 2006). For example, it is believed that the ROS concentration in the brain of Alzheimer's disease patients corresponds to an H ₂ O ₂ concentration of about 1.0 mM. In one embodiment, the polymer complex has a low molecular weight drug stably retained in the block copolymer without breaking the bond at about 0.04 mM or less corresponding to the H ₂ O ₂ concentration in blood, while Alzheimer's Under high ROS concentrations (such as in high oxidative stress; eg, high concentrations of H ₂ O _{2 of} about 1 mM or more) as in the brains of sick patients, bonds are cleaved and small molecule drugs are released.

  The drug delivery device of the present invention can be effectively used as a drug delivery device to a tissue having a high concentration of reactive oxygen species (for example, the brain of an Alzheimer's disease patient).

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[Example 1: Synthesis of various block copolymers PEG-PAsp (DET / FPBA)]
PEG-PAsp (DET / FPBA) was synthesized according to the following synthesis scheme.

1.1. Synthesis of PEG-PBLA β-benzyl-L-aspartate-N-carboxylic acid anhydride with α-methoxy-ω-amino-polyethylene glycol (MeO-PEG-NH ₂ , M _{w of} PEG: 2 kDa) as an initiator PEG-poly (β-benzyl L-aspartate) (PEG-PBLA) was synthesized by ring-opening polymerization of (NCA-BLA). 100 mg of MeO-PEG-NH ₂ was taken, dissolved in benzene and lyophilized overnight. After lyophilization, MeO-PEG-NH ₂ and NCA-BLA were completely dissolved in a mixed solvent of dimethylformamide (DMF): dichloromethane (DCM) = 1: 10 under Ar atmosphere, respectively, and the NCA-BLA solution and MeO-PEG were dissolved. to obtain a -NH ₂ solution. The NCA-BLA solution was added to the MeO-PEG-NH ₂ solution and stirred at 35 ° C. for 3 days. The reaction solution was reprecipitated into a mixed solution of n-hexane / ethyl acetate (3: 2) to recover PEG-PBLA. Thereafter, PEG-PBLA was vacuum-dried to obtain a white powder. The polymerization degree of PBLA was 35 (m = 35) (PEG-PBLA (m = 35)).
Thereafter, the same experimental steps were taken to obtain two other types of PEG-PBLA having different chain lengths (m = 51, 72; the degree of polymerization of each PBLA was 51, 72, respectively).

1.2. Synthesis of PEG-PAsp (DET) (aminolysis by DET)
PEG-PAsp (DET) was synthesized by aminolysis reaction of the collected PEG-PBLA.
Specifically, 200 mg of PEG-PBLA (m = 35) was dissolved in benzene and lyophilized. The dried PEG-PBLA was dissolved in 10 mL of N-methyl-2-pyrrolidone (NMP) under Ar atmosphere. In addition, Dry diethylenetriamine (DET) (50 equivalents to PBLA) was diluted with the same volume of NMP. These solutions were cooled to 10 ° C., and the PEG-PBLA solution was slowly added dropwise to the DET solution and stirred for 1 hour. After the reaction, the reaction solution was neutralized with 5N HCl aqueous solution while keeping the solution temperature at 10 ° C. or lower, and dialyzed for 1 day at 4 ° C. with 0.01N HCl aqueous solution. (MWCO 6000-8000 Da) Then, dialysis was performed for another day at 4 ° C. with ion-exchanged water. After dialysis, the solution was freeze-dried to obtain a white powder of PEG-PAsp (DET). The degree of polymerization of PAsp (DET) was 31 (PEG-PAsp (DET) (m = 31)).
In addition, PEG-PAsp (DET) having different chain lengths was obtained through the same experimental process for PEG-PBLA (m = 51, 72) having two different chain lengths. The degree of polymerization of each PAsp (DET) was 45 and 70, respectively (PEG-PAsp (DET) (m = 45, 70)).

1.3. Synthesis of PEG-PAsp (DET / FPBA) (FPBA modification with DMT-MM)
PEG-PAsp (DET / FPBA) was synthesized by a condensation reaction of PEG-PAsp (DET) and 4-carboxy-3-fluoro-phenylboronic acid (FPBA).
Specifically, 20 mg of PEG-PAsp (DET) (m = 31) and 4- (4,6-dimethoxy-1,3,5-triazin-2-yl) -4-methylmorpholinium chloride n hydration The product (DMT-MM) (5 equivalents to DET NH ₂ ) and sorbitol (5 equivalents to DET NH ₂ ) were dissolved in 50 mM NaHCO ₃ solution to prepare 1 mg / mL. On the other hand, FPBA (1 equivalent to NH _{2 of} DET) was dissolved in the same amount of methanol. The two solutions were mixed and reacted at 4 ° C. for 6 hours. After the reaction, dialysis was performed with 0.01N HCl aqueous solution at 4 ° C for 1 day. Thereafter, dialysis was performed with ion-exchanged water at 4 ° C. for another day. After dialysis (MWCO 6000-8000 Da), the solution was freeze-dried to obtain a white powder of PEG-PAsp (DET / FPBA). The degree of polymerization of PAsp (DET) was 24, of which FPBA was 17 units bonded, so the BA introduction rate was 24.1%. However, this BA introduction rate refers to the ratio of the molecular weight of the boronic acid group (BA molecular weight) to the molecular weight of the block copolymer. In this example, the BA molecular weight is a molecular weight having the following structure.

  In addition, PEG-PAsp (DET / FPBA) having the same chain length and three different BA introduction rates was synthesized by performing the same experimental process while changing the amount of FPBA added and the presence or absence of sorbitol. The BA introduction rates were 14.6%, 20.4%, and 30.2%, respectively.

Furthermore, the same two other types of PEG-PAsp (DET) (m = 45, 70) having different chain lengths were modified in the same manner, and PEG-PAsp (DET / DET / DET / 4) having four different BA introduction ratios in each chain length. FPBA) was synthesized.
The composition of the synthesized block copolymer (FPBA addition amount and presence / absence of sorbitol) is shown in Table 1. Hereinafter, each block copolymer is expressed as “PEG molecular weight—PAsp (DET) degree of polymerization before modification—BA introduction rate” in a form such as 2k-31-20.4%.

  As described above, the block copolymer in which the BA introduction rate was controlled at each PAsp (DET) polymerization degree was successfully synthesized.

[Example 2: Preparation of polymer micelle]
Polymeric micelles were prepared using PEG-PAsp (DET / FPBA) and rutin, a hydrophobic antioxidant with a diol structure.
A 10 mM acetate buffer (pH 4.0) was prepared using acetic acid and sodium acetate, and each block copolymer was dissolved in this solution to 1 mg / mL. Moreover, rutin was dissolved in ethanol so that it might become 1 mg / mL. The rutin solution was added to the block copolymer solution and stirred well, and the mixed solution was dialyzed overnight (MWCO: 20,000 Da) against PBS (pH 7.4) at 4 ° C. This was recovered after dialysis and each polymer micelle was prepared.

  A plurality of polymer micelles were prepared by performing the same experimental process while changing the molar ratio (Rutin / FPBA) of the amount of rutin added and the amount of FPBA contained in the block copolymer.

  The hydrodynamic diameter (particle size; Size) and polydispersity (PdI) of the prepared polymer micelles were measured by a dynamic light scattering (DLS) method using Zetasizer Nano (Malvern Instruments) (Table 2). The morphology of the polymer micelle was observed with a transmission electron microscope (TEM) by negative staining with a 1% gadolinium acetate solution. The particle size distribution and transmission electron microscope (TEM) images of polymer micelles (Rutin / FPBA = 0.25) prepared using 2k-45-22.7% as representative are shown (FIGS. 3 and 4).

As described above, a polymer assembly (polymer complex) in which rutin was incorporated into each block copolymer (PEG-PAsp (DET / FPBA)) was successfully formed.
Furthermore, polymer micelles were successfully formed by controlling the FPBA introduction rate and Rutin / FPBA. In particular, when the BA introduction rate and Rutin / FPBA are in a specific range, it was confirmed that a region where a polymer micelle having a particle size of about 30 nm can be formed is limited. In particular, in this example, when the BA introduction rate was 20 to 25%, monodispersed (low PDI) polymer micelles of around 30 nm were obtained. In addition, it was confirmed that the polymer micelle having a particle size of about 30 nm (about 20 to 40 nm) obtained at each PAsp (DET) degree of polymerization (31, 45, 70) has a spherical and monodisperse particle size distribution. It was done.

[Example 3: Particle size change at different pH]
Polymer micelles made of 2k-70-23.3% (Rutin / FPBA = 0.1) prepared in Example 2 were used. The solvent of the prepared polymer micelle was replaced with PBS having a different pH by dialysis. The selected solvent was 10 mM PBS, and the substituted pH was 7.4 and 8.5, respectively. The hydrodynamic diameter (particle diameter) at 37 ° C. of polymer micelles in each solvent was measured over time by the DLS method (apparatus: Zetasizer Nano (Malvern Instruments)). The result is shown in FIG.

As shown in FIG. 5, the particle size of the polymer micelle gradually increased at pH 7.4, whereas the change in particle size was suppressed at pH 8.5. From this result, it is considered that electrostatic repulsion by protonated NH ₂ has a negative effect on the stability of the polymer micelle.

[Example 4: Structural stability evaluation of polymer micelles]
Among the polymer micelles obtained in Example 2, those having a monodisperse particle size distribution with a hydrodynamic diameter of around 30 nm and PdI of less than 0.2 are obtained for each PAsp (DET) polymerization degree. Each one was selected and its structural stability at 37 ° C. in PBS (pH 7.4) was evaluated. That is, as a polymer micelle, 2k-31-20.4% (Rutin / FPBA = 0.5), 2k-45-22.7% (Rutin / FPBA = 0.25), 2k-70-23.3. % (Rutin / FPBA = 0.1) was used. The particle size was measured in the same manner as in Example 3. The result is shown in FIG.

From FIG. 6, it was confirmed that 2k−45 to 22.7% exhibited the highest structural stability with the smallest increase in particle size. This is because when the degree of polymerization is too small, the micelle core is not sufficiently filled. On the other hand, as the degree of polymerization increases, the number of NH ₂ simultaneously increases with the number of FPBA. This is thought to be due to destabilizing the core.

[Example 5: Verification of polymer micelle formation process]
Using the polymer micelle composed of 2k-45-22.7% (Rutin / FPBA = 0.25) which showed the highest structural stability in Example 4, an experiment on the formation process of the polymer micelle was performed.
Specifically, the block copolymer (2k-45-22.7%) was dissolved in an acetic acid buffer (pH 4.0) in the same manner as in Example 2, and rutin was dissolved in ethanol and mixed. After stirring well, dialysis was performed against external solutions having different pHs to prepare polymer micelles. Moreover, the polymer micelle formation change by the presence or absence of NaCl was similarly prepared. Similar to Example 2, the particle size (Size) and PdI were measured by the DLS method. The results are shown in Table 3.

PdI ≦ 0.20 is an index for forming spherical and monodisperse polymer micelles.
As shown in Table 3, monodisperse polymer micelle formation was not confirmed in the low pH region (pH 4.0 and 5.7), but monodisperse polymer micelle formation was confirmed at pH 6.5 or higher. It was. This suggests that electrostatic repulsion due to protonation of NH ₂ also contributes greatly to the formation of polymer micelles. The pKa of the second protonation of DET is said to be 6.0, and in this result, the formation of monodisperse polymer micelles was confirmed only above the pH. On the other hand, it was suggested that the presence or absence of NaCl does not contribute to the formation of the polymer micelle.

[Example 6: Change in particle size of polymer micelle in the presence of H ₂ O ₂ ]
Using the polymer micelle prepared in Example 2 and composed of 2k-45-22.7% (Rutin / FPBA = 0.25), the particle size (Size) of the polymer micelle in the presence of H ₂ O ₂ The change in dispersity (PdI) was measured over time. The H ₂ O ₂ concentration was adjusted to the brain environment ROS concentration (1 mM) and blood H ₂ O ₂ concentration (0.1 mM) of Alzheimer's disease patients. The results are shown in FIGS. 7A and 7B.

As shown in FIGS. 7A and 7B, no change in the particle size of the polymer micelles occurred when 0.1 mM H ₂ O _{2 was} present. On the other hand, when 1 mM H ₂ O _{2 was} present, the particle size of the polymer micelles increased rapidly, and an increase in PdI was also confirmed. From these results, it was suggested that the polymer micelle was disintegrated.

[Example 7: Change in absorption spectrum of rutin in the presence of H ₂ O ₂ ]
The influence of H ₂ O _{2 on the} rutin absorption peak was verified. 1 mM H ₂ O ₂ was added to rutin and allowed to stand at 37 ° C., and the change in absorption spectrum was measured over time. The result is shown in FIG. FIG. 8A shows the change with time of the absorption spectrum of rutin in the absence of H ₂ O ₂ (ie, in PBS). FIG. 8B shows the change with time in the absorption spectrum of rutin in the presence of 1 mM H ₂ O ₂ .

From this result, it was confirmed that the absorption peak derived from rutin and its absorbance do not depend on the H ₂ O ₂ concentration in this experimental condition.

[Example 8: Absorption spectrum change of polymer micelle in the presence of H ₂ O ₂ ]
The polymer micelle prepared in Example 2 and composed of 2k-45-22.7% (Rutin / FPBA = 0.25) was used. In the same manner as in Example _6, H 2 _{O 2} in the absence (i.e. in PBS), 1mMH ₂ O ₂ presence, measured over time absorbance spectrum changes in polymeric micelles of 0.1 mM H ₂ O ₂ presence did. The result is shown in FIG. FIG. 9A shows the time course of the absorption spectrum of the polymer micelle in the presence of 1 mM H ₂ O ₂ , and FIG. 9B shows the time course of the absorption spectrum of the polymer micelle in the presence of 0.1 mM H ₂ O ₂ . Indicates the time course of the absorption spectrum of polymer micelles in the absence of H ₂ O ₂ (ie in PBS).

From FIG. 9A to FIG. 9C, similar to the particle size change in Example 7 (FIGS. 8A and 8B), it did not respond to 0.1 mM H ₂ O ₂ , and the absorption peak shifted in the presence of 1 mM H ₂ O ₂ . It was confirmed. This is considered to be because the electronic state of the quercetin structure in rutin was changed by binding to FPBA. That is, the shift of the absorption peak represents the cleavage of the FPBA-rutin bond, suggesting the collapse of the polymer micelle in response to H ₂ O ₂ .

From the above examples, rutin as a low-molecular-weight drug containing a binding site with a boronic acid group is stably supported on the copolymer through the binding between the binding site and the boronic acid group of the block copolymer. It was confirmed.
Further, by controlling the introduction rate of boronic acid group (BA introduction rate) and the ratio of low molecular drug / boronic acid group (Rutin / FPBA) to the block copolymer, It was confirmed that a polymer micelle encapsulating a molecular drug (Rutin) was formed.
High molecular micelles containing a low molecular drug (Rutin) containing a binding site with a boronic acid group show H ₂ O ₂ responsiveness, and block the drug binding site and block in the presence of H ₂ O _{2 at} a specific concentration or higher. It was confirmed that the drug was released by cleaving the bond with the boronic acid group of the copolymer.

  The polymer composite of the present invention can be suitably applied in the field of DDS.

DESCRIPTION OF SYMBOLS 1 Polymer segment 2 Boronic acid group 3 Hydrophilic polymer chain segment 4 Ligand 5, 5a, 5b Block copolymer 6 Low molecular drug 7 Drug inclusion polymer micelle 8 Reactive oxygen species (ROS)

Claims (13)

A block copolymer having a polymer segment having at least one boronic acid group selected from a phenylboronic acid group or a pyridylboronic acid group in the side chain, and a hydrophilic polymer segment;
A low molecular weight drug comprising a binding site with the boronic acid group;
A polymer composite comprising   2. The composite according to claim 1, wherein the binding site with the boronic acid group is at least one selected from a polyol structure, a diamine structure, a hydroxyamine structure, a hydroxamic acid structure, an alkoxycarboxyamide structure, and a diphosphate structure. body.   The complex according to claim 1 or 2, wherein the low molecular weight drug is a hydrophobic substance.   The block copolymer is radially arranged so that the polymer segment is on the inside and the hydrophilic polymer segment is on the outside to form a micelle, and the low-molecule drug is encapsulated in the micelle. The complex according to any one of 1 to 3.   The complex according to any one of claims 1 to 4, wherein the polymer segment is composed of a polyamino acid, and the boronic acid group is introduced into a side chain of the polyamino acid.   The hydrophilic polymer segment includes poly (ethylene glycol), polysaccharide, poly (vinyl pyrrolidone), poly (vinyl alcohol), poly (acrylamide), poly (acrylic acid), poly (methacrylamide), poly (methacrylic acid). ), Poly (methacrylic acid ester), poly (acrylic acid ester), polyhydroxyethyl acrylate, poly (hydroxyethyl methacrylate), polyamino acid, poly (malic acid), poly (2-methyl-2-oxazoline), 6. A hydrophilic polymer selected from poly (2-ethyl-2-oxazoline), poly (2-isopropyl-2-oxazoline), or derivatives thereof, according to any one of claims 1-5. Complex. The boronic acid group is a phenylboronic acid group (PBA) represented by the following formula (b1) or a pyridylboronic acid group represented by the following formula (b2). Complex.
(In the above formula,
R _b represents halogen selected from fluorine, chlorine, bromine, or iodine, or nitro;
n is an integer from 0 to 4,
* Indicates the point of attachment to the polymer chain) The said block copolymer is a composite_body | complex as described in any one of Claims 1-7 represented by following formula (3).
(Where
R ¹ is a hydrogen atom or an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms;
R ² represents a hydrogen atom, an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms, or an unsubstituted or substituted linear or branched alkylcarbonyl group having 1 to 24 carbon atoms. Group,
R ^4a is, independently of one another, a methylene group or an ethylene group,
L ¹ is —SS— or a valence bond,
L ² is —NH—, —O—, —O (CH ₂ ) _p1 —NH—, or —L ^2a — (CH ₂ ) _q1 -L ^2b —, wherein p1 and q1 are Independently, an integer from 1 to 5, L ^2a is OCO, OCONH, NHCO, NHCOO, NHCONH, CONH or COO, L ^2b is NH or O,
R ^9a is a divalent group represented by —NH— (CH ₂ ) _{p 2} — [NH— (CH ₂ ) _{q 2} —] _r 2 NH—, and p 2, q 2, and r 2 are independently from each other. , An integer from 1 to 5,
R ^9b is —NH— (CH ₂ ) _{p 3} — [NH— (CH ₂ ) _{q 3} —] _{r 3} NH ₂ , and p 3, q 3 and r 3 are each independently an integer of 1 to 5 Yes BA represents a boronic acid group x is 0.1 to 0.9,
m is an integer of 1 to 300. )   The complex according to any one of claims 1 to 8, wherein a surface of the complex is modified with glucose or a glucose derivative.   The composition containing the composite_body | complex as described in any one of Claims 1-9.   The composition according to claim 10, wherein the low molecular drug is released from the polymer complex in the presence of reactive oxygen species.   The composition according to claim 12 or 11, which is used for delivering the small molecule drug to the brain.   A drug delivery device comprising the complex according to any one of claims 1 to 9 or the composition according to any one of claims 10 to 12.