POLYMER CONTRAST AGENT

Abstract

A copolymer includes a copolymer X and a chelating agent molecule bonded to the copolymer X. The copolymer X includes structural units of (A), (B), and (C),

##STR00001##

where R.sup.1, R.sup.2, and R.sup.3 are independently a hydrogen or a C.sub.1-3 alkyl, R.sup.4 is a C.sub.1-3 alkyl, R.sup.5 is a hydrogen, a C.sub.1-18 alkyl, a 3- to 8-membered cycloalkyl optionally having a substituent, an adamantyl, a C.sub.6-18 aryl optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, X.sup.1, X.sup.2, and X.sup.3 are independently an oxygen, a sulfur, or NR.sup.7, R.sup.6 is a hydrogen, a leaving group, or a linker, R.sup.7 is a hydrogen or a C.sub.1-3 alkyl group, m is an integer in the range of 1 to 100, and n is an integer in the range of 0 to 3.

Claims

1. A copolymer, comprising: a copolymer X; and a chelating agent molecule bonded to the copolymer X, wherein the copolymer X comprises structural units of formula (A), formula (B), and formula (C), ##STR00032## where R.sup.1, R.sup.2, and R.sup.3 are the same or different and are a hydrogen atom or a C.sub.1-3 alkyl group, R.sup.4 is a C.sub.1-3 alkyl group, R.sup.5 is a hydrogen atom, a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, X.sup.1, X.sup.2, and X.sup.3 are the same or different and are an oxygen atom, a sulfur atom, or NR.sup.7, R.sup.6 is a hydrogen atom, a leaving group, or a linker, R.sup.7 is a hydrogen atom or a C.sub.1-3 alkyl group, m is an integer of 1 to 100, and n is an integer of 0 to 3.

2. The copolymer according to claim 1, wherein the polymer X is a copolymer formed by polymerization of three monomers of formula (1), formula (2), and formula (3), ##STR00033## where R.sup.1, R.sup.2, and R.sup.3 are the same or different and are a hydrogen atom or a C.sub.1-3 alkyl group, R.sup.4 is a C.sub.1-3 alkyl group, R.sup.5 is a hydrogen atom, a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, X.sup.1, X.sup.2, and X.sup.3 are the same or different and are an oxygen atom, a sulfur atom, or NR.sup.7, R.sup.6 is a hydrogen atom, a leaving group, or a linker, R.sup.7 is a hydrogen atom or a C.sub.1-3 alkyl group, m is an integer of 1 to 100, and n is an integer of 0 to 3.

3-18. (canceled)

19. The copolymer according to claim 1, wherein the copolymer has a number average molecular weight in a range of 5,000 to 150,000.

20. The copolymer according to claim 1, wherein the chelating agent molecule is a molecule having a residue of formula (a), ##STR00034## where R.sup.8 is a hydrogen atom or a hydroxyalkyl group R.sup.9 and R.sup.10 are a hydrogen atom or [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]* and are different such that when R.sup.9 is a hydrogen atom, R.sup.10 is [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]*, and when R.sup.9 is [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]*, R.sup.10 is a hydrogen atom, X.sup.4 is an oxygen atom, a sulfur atom, NR.sup.7, or CH.sub.2O, Y and Y are a hydrogen atom, a methyl group, or a hydroxy group, or Y and Y together are an oxygen atom, L is an arylene group, a cycloalkylene group, SS, C(O)O, OC(O), C(O)NH, NHC(O), NHC(O)O, OC(O)NH, or a peptide bond including 1 to 4 amino acid residues, * is a bond to the copolymer, and o and p independently are an integer of 0 to 10.

21. The copolymer according to claim 1, wherein the chelating agent molecule is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,2,3-triacetic acid (HP-DO3A), 10-[1,1,1-tris(hydroxymethyl)methyl]-1,4,7-triscarboxymethyl-1,4,7,10-tetraazacyclododecane (DO3A-butrol), 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid-10-(2-thioethyl)acetamide (DO3A-Thiol), or S-2-(4-aminobenzyl)-1,4,7,10-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA-p-NH.sub.2Bn).

22. The copolymer according to claim 1, wherein the chelating agent molecule is bonded to the copolymer X by a covalent bond or a non-covalent bond.

23. A polymer contrast agent, comprising: the copolymer of claim 1; and a paramagnetic metal.

24. The polymer contrast agent according to claim 23, wherein the paramagnetic metal is gadolinium or manganese.

25. A diagnostic imaging drug, comprising: the copolymer of claim 1; and a paramagnetic metal.

26. The diagnostic imaging drug according to claim 25, wherein the paramagnetic metal is gadolinium or manganese.

27. A single chain nanoparticle, comprising: the copolymer of claim 1.

28. A pharmaceutical composition, comprising: the copolymer of claim 1.

29. A single chain nanoparticle, comprising: the copolymer of claim 1.

30. A single chain nanoparticle, comprising: the polymer contrast agent of claim 23.

31. A single chain nanoparticle, comprising: the diagnostic imaging drug of claim 25.

32. The copolymer according to claim 2, wherein the copolymer has a number average molecular weight in a range of 5,000 to 150,000.

33. The copolymer according to claim 2, wherein the chelating agent molecule is a molecule having a residue of formula (a), ##STR00035## where R.sup.8 is a hydrogen atom or a hydroxyalkyl group, R.sup.9 and R.sup.10 are a hydrogen atom or [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]* and are different such that when R.sup.9 is a hydrogen atom, R.sup.10 is [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]*, and when R.sup.9 is [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]*, R.sup.10 is a hydrogen atom, X.sup.4 is an oxygen atom, a sulfur atom, NR.sup.7, or CH.sub.2O, Y and Y are a hydrogen atom, a methyl group, or a hydroxy group, or Y and Y together are an oxygen atom, L is an arylene group, a cycloalkylene group, SS, C(O)O, OC(O), C(O)NH, NHC(O), NHC(O)O, OC(O)NH, or a peptide bond including 1 to 4 amino acid residues, * is a bond to the copolymer, and o and p independently are an integer of 0 to 10.

34. The copolymer according to claim 2, wherein the chelating agent molecule is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,2,3-triacetic acid (HP-DO3A), 10-[1,1,1-tris(hydroxymethyl)methyl]-1,4,7-triscarboxymethyl-1,4,7,10-tetraazacyclododecane (DO3A-butrol), 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid-10-(2-thioethyl)acetamide (DO3A-Thiol), or S-2-(4-aminobenzyl)-1,4,7,10-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA-p-NH.sub.2Bn).

35. The copolymer according to claim 2, wherein the chelating agent molecule is bonded to the copolymer X by a covalent bond or a non-covalent bond.

36. A polymer contrast agent, comprising: the copolymer of claim 2; and a paramagnetic metal.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0058] FIG. 1 is a diagram showing a .sup.1H-NMR spectrum of a copolymer obtained in Example 1, measured by using nuclear magnetic resonance (NMR).

[0059] FIG. 2 is a diagram showing a chromatogram of the copolymer obtained in Example 1, obtained by gel permeation chromatography (GPC).

[0060] FIG. 3 is a diagram showing a .sup.1H-NMR spectrum of a copolymer obtained in Example 69, measured by using the nuclear magnetic resonance (NMR).

[0061] FIG. 4 is a diagram showing a chromatogram of the copolymer obtained in Example 69, obtained by gel permeation chromatography (GPC).

[0062] FIG. 5 is a diagram showing a UV spectrum of a copolymer obtained in Example 98, measured by using ultraviolet spectrum measurement (UV).

[0063] FIG. 6 is a diagram showing a .sup.1H-NMR spectrum of a chelating agent-bonded copolymer obtained in Example 106, measured by using the nuclear magnetic resonance (NMR).

[0064] FIG. 7 is a diagram showing a .sup.1H-NMR spectrum of a chelating agent-bonded copolymer obtained in Example 134, measured by using the nuclear magnetic resonance (MAR).

[0065] FIG. 8 is a diagram showing a .sup.1H-NMR spectrum of a chelating agent-bonded copolymer obtained in Example 142, measured by using the nuclear magnetic resonance (MAR).

[0066] FIG. 9 is a diagram showing a .sup.1H-NMR spectrum of a chelating agent-bonded copolymer obtained in Example 150, measured by using the nuclear magnetic resonance (NMR).

[0067] FIG. 10 is a diagram showing a .sup.1H-NMR spectrum of a chelating agent-bonded copolymer obtained in Example 151, measured by using the nuclear magnetic resonance (MAR).

[0068] FIG. 11 is a diagram showing a particle diameter measurement result (scattering intensity distribution) of a Gd-DOTA-bonded SCNP obtained in Example 152 in dynamic light scattering (DLS).

[0069] FIG. 12 is a diagram showing a temporal change in the imaging ability of the Gd-DOTA-bonded SCNP obtained in Example 152 in a contrast test on the C26-transplanted, tumor-bearing mouse.

DESCRIPTION OF EMBODIMENTS

[0070] Terms in the present description are used in the meanings commonly used in the field unless otherwise specified. Hereinafter, the present invention will be described in more detail.

[0071] In the present description, the term nanoparticle refers to a structure having a particle diameter of 100 nm or less.

[0072] In the present description, the term single chain nanoparticle (SCNP) refers to a nanoparticle formed by using, for example, chemical crosslinking, hydrophobic interaction, or ionic bonding in a single chain as a driving force. The SCNP often indicates a nanoparticle having a relatively small particle diameter of 20 nm or less among nanoparticles.

[0073] In the present description, the term initiator means an initiator for thermal radical polymerization such as an azo compound or a peroxide.

[0074] In the present specification, the term chain transfer agent refers to a compound that causes a chain transfer reaction in radical polymerization, and is preferably a compound having a thiocarbonyl group.

[0075] In the present description, the term C.sub.1-3 alkyl group means a linear or branched, alkyl group having 1 to 3 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

[0076] In the present description, the term C.sub.1-18 alkyl group means a linear or branched, alkyl group having 1 to 18 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group.

[0077] In the present description, the term 3- to 8-membered cycloalkyl group optionally having a substituent means a cyclic alkyl group having 3 to 8 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The substituent is not particularly limited, and examples thereof include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an alkylamino group having 1 to 6 carbon atoms, a di-alkylamino group having 1 to 6 carbon atoms in which alkyl groups are the same or different, a thiol group, an alkylthio group having 1 to 6 carbon atoms, a carboxyl group, an alkoxycarbonyl group having 1 to 6 carbon atoms, and a carbamoyl group.

[0078] In the present description, the term C.sub.6-18 aryl group optionally having a substituent means a monocyclic or polycyclic condensed aromatic hydrocarbon group, and examples thereof include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, and a naphthacenyl group. Further, a C.sub.6-14 aryl group optionally having a substituent means a monocyclic or polycyclic condensed aromatic hydrocarbon group, and examples thereof include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group. The substituent is not particularly limited, and examples thereof include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an alkylamino group having 1 to 6 carbon atoms, a di-alkylamino group having 1 to 6 carbon atoms in which alkyl groups are the same or different, a thiol group, an alkylthio group having 1 to 6 carbon atoms, a carboxyl group, an alkoxycarbonyl group having 1 to 6 carbon atoms, and a carbamoyl group.

[0079] In the present description, the term 5- to 10-membered heteroaryl group optionally having a substituent means a 5- to 10-membered, monocyclic aromatic heterocyclic group or condensed aromatic heterocyclic group containing 1 to 4 heteroatoms selected from a nitrogen atom, an oxygen atom, and a sulfur atom, other than a carbon atom, as atoms constituting the ring. Examples of the monocyclic aromatic heterocyclic group include a furyl group, a thienyl group, a pyrrolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an imidazolyl group, a pyrazyl group, a thiallyl group, an oxazolyl group, an isoxazolyl group, a 1,3,4-thiadiazolyl group, a 1,2,3-triazolyl group, a 1,2,4-triazolyl group, and a tetrazolyl group. Examples of the condensed aromatic heterocyclic group include a benzofuranyl group, a benzothiophenyl group, a quinoxalinyl group, an indolyl group, an isoindolyl group, an isobenzofuranyl group, a chromanyl group, a benzimidazolyl group, a benzothiazolyl group, a benzoxazolyl group, a quinolyl group, and an isoquinolinyl group. The term 6- to 10-membered heteroaryl group optionally having a substituent means a 6- to 10-membered, monocyclic aromatic heterocyclic group or condensed aromatic heterocyclic group containing 1 to 4 heteroatoms selected from a nitrogen atom, an oxygen atom, and a sulfur atom, other than a carbon atom, as the atoms constituting the ring. Examples of the monocyclic aromatic heterocyclic group include a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, and a pyridazinyl group. Examples of the condensed aromatic heterocyclic group include a benzofuranyl group, a benzothiophenyl group, a quinoxalinyl group, an indolyl group, an isoindolyl group, an isobenzofuranyl group, a chromanyl group, a benzimidazolyl group, a benzothiazolyl group, a benzoxazolyl group, a quinolyl group, and an isoquinolinyl group. The substituent is not particularly limited, and examples thereof include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an alkylamino group having 1 to 6 carbon atoms, a di-alkylamino group having 1 to 6 carbon atoms in which alkyl groups are the same or different, a thiol group, an alkylthio group having 1 to 6 carbon atoms, a carboxyl group, an alkoxycarbonyl group having 1 to 6 carbon atoms, and a carbamoyl group.

[0080] In the present description, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0081] In the present description, the hydroxyalkyl group means a linear or branched, alkyl group having 1 to 3 carbon atoms in which one hydrogen atom is substituted with a hydroxyl group, and examples thereof include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group.

[0082] In the present description, the arylene group means a divalent aromatic hydrocarbon cyclic group having 6 to 10 carbon atoms, and examples thereof include phenylene and naphthylene.

[0083] In the present description, the cycloalkylene group means a divalent cyclic saturated hydrocarbon group having 3 to 7 carbon atoms, and examples thereof include cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, and cycloheptylene.

[0084] In the present description, the contrast agent is a compound to be administered into the body for purpose of improving accuracy of diagnostic imaging, and is a drug used in, for example, the MRI, computed tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), or ultrasonic diagnostic imaging. The contrast agent is usually a compound (contrast agent molecule) in which the paramagnetic metal is coordinated to respective chelating agent molecules. The contrast agent molecule may be loaded into the copolymer by an action such as electrostatic interaction, hydrogen bond, hydrophobic interaction, or covalent bond to the copolymer X of the present invention.

[0085] In the present description, the chelating agent molecule is a compound that forms a complex by a coordination bond to a metal ion. The metal ion is preferably a paramagnetic metal ion.

[0086] In the present description, the pharmaceutical composition means one composed of the copolymer (hereinafter, also referred to as the chelating agent-bonded copolymer or the contrast agent molecule-bonded copolymer) in which the chelating agent molecule or the contrast agent molecule is bonded to (loaded into due to an action such as electrostatic interaction, hydrogen bond, hydrophobic interaction, or covalent bond) the copolymer X of the present invention, and a carrier. Examples of the loading form of the contrast agent molecule include a form in which the contrast agent molecule is present on the particle surface, a form in which the contrast agent molecule is contained in a nanoparticle, and a combination form thereof where the contrast agent molecule-bonded copolymer forms the nanoparticle.

[0087] One embodiment of the present invention is a copolymer (chelating agent molecule-bonded copolymer or contrast agent molecule-bonded copolymer) in which a chelating agent molecule or a contrast agent molecule is bonded to a copolymer X having structural units represented by the following formulas (A), (B), and (C):

##STR00007## [0088] wherein, R.sup.1, R.sup.2, and R.sup.3 are the same or different and represent a hydrogen atom or a C.sub.1-3 alkyl group, R.sup.4 represents a C1-3 alkyl group, R.sup.5 represents a hydrogen atom, a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, X.sup.1, X.sup.2, and X.sup.3 are the same or different and represent an oxygen atom, a sulfur atom, or NR.sup.7, R.sup.6 represents a hydrogen atom, a leaving group, or a linker, R.sup.7 represents a hydrogen atom or a C1-3 alkyl group, m represents an integer of 1 to 100, and n represents an integer of 0 to 3.

[0089] In the copolymer X of the present invention, the structural unit (A) functions as a unit that imparts hydrophilicity, and the structural unit (B) functions as a unit that imparts hydrophobicity. Further, the structural unit (C) functions as a scaffold to which an active ingredient (drug or contrast agent molecule) is bonded to the copolymer X, the chelating agent molecule-bonded copolymer, or the contrast agent molecule-bonded copolymer. Having these three structural units serves to imparting the copolymer X, the chelating agent molecule-bonded copolymer, or the contrast agent molecule-bonded copolymer of the present invention a property of forming SCNP in water, and to facilitating the formed SCNP to precisely control particle diameter at a minute scale of 20 nm or less, and to function as a drug delivery carrier having high tumor accumulation. [0090] R.sup.1 in the structural unit (A) represents a hydrogen atom or a C.sub.1-3 alkyl group, and is preferably a hydrogen atom or a methyl group, preferably a hydrogen atom, an ethyl group, or a propyl group, and more preferably a hydrogen atom. [0091] X.sup.1 represents an oxygen atom, the sulfur atom, or NR.sup.7, and is preferably an oxygen atom, a sulfur atom, or NH, and more preferably an oxygen atom. [0092] m represents an integer of 1 to 100, preferably an integer of 3 to 100, and from a viewpoint of imparting good hydrophilicity, preferably 3 to 80, more preferably from 4 to 60, still more preferably 4 to 40, and yet more preferably from 4 to 22. [0093] R.sup.4 represents a C.sub.1-3 alkyl group, specifically a methyl group, an ethyl group, an n-propyl group or an isopropyl group, preferably a methyl group or an ethyl group, and more preferably a methyl group. [0094] R.sup.2 in the structural unit (B) represents a hydrogen atom or a C.sub.1-3 alkyl group, and is preferably a hydrogen atom or a methyl group, preferably a hydrogen atom, an ethyl group, or a propyl group, and more preferably a hydrogen atom. [0095] X.sup.2 represents an oxygen atom, a sulfur atom, or NR.sup.7, and is preferably an oxygen atom, a sulfur atom, or NH, and more preferably an oxygen atom. [0096] n represents an integer of 0 to 3, preferably an integer of 1 to 3, and more preferably 1. [0097] R.sup.5 represents a hydrogen atom, a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.1-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, and from a viewpoint of imparting the hydrophobicity to the structural unit (B), preferably a C.sub.1-13 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, more preferably a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, and still more preferably a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group, an adamantyl group, or a C.sub.6-18 aryl group. Meanwhile, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-14 aryl group optionally having a substituent, or a 6- to 10-membered heteroaryl group optionally having a substituent is also preferable. Here, the substituent is preferably one or more types selected from a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, and an alkynyl group having 2 to 6 carbon atoms. [0098] R.sup.3 in the structural unit (C) represents a hydrogen atom or a C.sub.1-3 alkyl group, and is preferably a hydrogen atom or a methyl group, preferably a hydrogen atom, an ethyl group, or a propyl group, and more preferably a hydrogen atom. [0099] X.sup.3 represents an oxygen atom, a sulfur atom, or NR.sup.7, and is preferably an oxygen atom, a sulfur atom, or NH, and more preferably an oxygen atom. [0100] R.sup.6 represents a hydrogen atom, a leaving group, or a linker. The leaving group is a group that can detach when the structural unit (C) binds to the drug (contrast agent molecule) or the chelating agent molecule, and the linker is a group that can be used for crosslinking when the structural unit (C) binds to the drug (contrast agent molecule) or the chelating agent molecule. As the leaving group or linker, a C.sub.1-18 alkyl group optionally having a substituent, a 3- to 8-membered cycloalkyl group optionally having a substituent, or a C.sub.7-19 aralkyl group optionally having a substituent is preferable. Here, examples of the substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an alkylamino group having 1 to 6 carbon atoms, a di-alkylamino group having 1 to 6 carbon atoms in which alkyl groups are the same or different, a thiol group, an alkylthio group having 1 to 6 carbon atoms, a carboxyl group, an alkoxycarbonyl group having 1 to 6 carbon atoms, and a carbamoyl group. Among these groups, the linker is preferably a group having a functional group such as a hydroxyl group, an amino group, a thiol group, or a carboxyl group as a substituent.

[0101] Preferred examples of the leaving group of R.sup.6 include a group represented by the following formula (4):

##STR00008##

[0102] Preferred examples of the linker of R.sup.6 include groups selected from the following formulas (5) to (7).

##STR00009##

No Text.

[0103] The copolymer X of the present invention is the copolymer having the structural units represented by formulas (A), (B) and (C). The copolymer X may be a random copolymer or a block copolymer and is preferably a random copolymer. As for a composition ratio of each structural unit in one molecule, when (A) is 1 part by mass, preferably (B) is 0.01 to 100 parts by mass and (C) is 0.1 to 100 parts by mass; more preferably (B) is 0.05 to 18 parts by mass and (C) is 0.1 to 20 parts by mass, and particularly preferably (B) is 0.05 to 4 parts by mass and (C) is 0.1 to 16 parts by mass.

[0104] A polymerization degree of the copolymer X of the present invention is not particularly limited, and the number average molecular weight thereof is preferably 5,000 to 150,000, and more preferably 8,000 to 150,000.

[0105] In the copolymer of the present invention, as described above, the monomer represented by general formula (1) functions as a unit that imparts the hydrophilicity, and the monomer represented by general formula (2) functions as a unit that imparts the hydrophobicity. Further, the monomer represented by general formula (3) functions as a scaffold to which the drug and the copolymer are bonded. Examples of the monomer functioning as the hydrophobic unit represented by general formula (2) include monomers represented by the following formulas.

##STR00010## ##STR00011## ##STR00012## ##STR00013## ##STR00014## ##STR00015## ##STR00016## ##STR00017##

No Text.

[0106] In general formula (1), R.sup.1 represents a hydrogen atom or a C1-3 alkyl group, and is preferably a hydrogen atom or a methyl group, preferably a hydrogen atom, an ethyl group, or a propyl group, and more preferably a hydrogen atom.

[0107] In general formula (2), R.sup.2 represents a hydrogen atom or a C.sub.1-3 alkyl group, and is preferably a hydrogen atom or a methyl group, preferably a hydrogen atom, an ethyl group, or a propyl group, and more preferably a hydrogen atom.

[0108] In general formula (3), R.sup.3 represents a hydrogen atom or a C.sub.1-3 alkyl group, and is preferably a hydrogen atom or a methyl group, preferably a hydrogen atom, an ethyl group, or a propyl group, and more preferably a hydrogen atom.

[0109] In general formula (1), R.sup.4 represents a C.sub.1-3 alkyl group, specifically a methyl group, an ethyl group, an n-propyl group or an isopropyl group, preferably a methyl group or an ethyl group, and more preferably a methyl group.

[0110] In general formula (1), X.sup.1 represents an oxygen atom, a sulfur atom, or NR.sup.7, and is preferably an oxygen atom, a sulfur atom, or NH, and more preferably an oxygen atom.

[0111] In general formula (1), m represents an integer of 1 to 100, and is preferably an integer of 3 to 100, and preferably 3 to 80, more preferably 4 to 60, still more preferably 4 to 40, and yet more preferably 4 to 22 from the viewpoint of imparting good hydrophilicity.

[0112] In general formula (2), R.sup.5 represents a hydrogen atom, a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent, and from the viewpoint of imparting hydrophobicity to the structural unit (B), a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent is preferable, a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-18 aryl group optionally having a substituent, or a 5- to 10-membered heteroaryl group optionally having a substituent is more preferable, and a C.sub.1-18 alkyl group, a 3- to 8-membered cycloalkyl group, an adamantyl group, or a C.sub.6-18 aryl group is still more preferable. In addition, a 3- to 8-membered cycloalkyl group optionally having a substituent, an adamantyl group, a C.sub.6-14 aryl group optionally having a substituent, or a 6- to 10-membered heteroaryl group optionally having a substituent is also preferable. Here, the substituent is preferably one or more selected from a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, and an alkynyl group having 2 to 6 carbon atoms.

[0113] In general formula (2), X.sup.2 represents an oxygen atom, a sulfur atom, or NR.sup.7, and is preferably an oxygen atom, a sulfur atom, or NH, and more preferably an oxygen atom.

[0114] In general formula (2), n represents an integer of 0 to 3, preferably an integer of 1 to 3, and more preferably 1.

[0115] In general formula (3), R.sup.6 represents a hydrogen atom, a leaving group, or a linker. As the leaving group or linker, a C.sub.1-18 alkyl group optionally having a substituent, a 3- to 8-membered cycloalkyl group optionally having a substituent, or a C.sub.7-19 aralkyl group optionally having a substituent is preferable. Here, examples of the substituent include a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 6 carbon atoms, an amino group, an alkylamino group having 1 to 6 carbon atoms, a di-alkylamino group having 1 to 6 carbon atoms in which alkyl groups are the same or different, a thiol group, an alkylthio group having 1 to 6 carbon atoms, a carboxyl group, an alkoxycarbonyl group having 1 to 6 carbon atoms, and a carbamoyl group. Among these groups, as the linker, a group having a functional group such as a hydroxyl group, an amino group, a thiol group, or a carboxyl group as a substituent is preferable.

[0116] Preferred specific examples of the leaving group of R.sup.6 include a group represented by the following formula (4):

##STR00018##

[0117] Preferred specific examples of the linker of R.sup.3 include groups selected from the following formulas (5) to (7):

##STR00019##

No Text.

[0118] In general formula (3), X.sup.3 represents an oxygen atom, a sulfur atom, or NR.sup.7, and is preferably an oxygen atom, a sulfur atom, or NH, and more preferably an oxygen atom.

[0119] The copolymer X of the present invention is formed by copolymerizing three monomers represented by general formulas (1) to (3). The copolymerization may be random copolymerization or block copolymerization, and those formed by random copolymerization are preferable. As for a blending ratio of the three monomers, it is preferable that 0.01 to 100 parts by mass of monomer (2) and 0.1 to 100 parts by mass of monomer (3) are polymerized, it is more preferable that 0.05 to 18 parts by mass of monomer (2) and 0.1 to 20 parts by mass of monomer (3) are polymerized, and it is particularly preferable that 0.05 to 4 parts by mass of monomer (2) and 0.1 to 16 parts by mass of monomer (3) are polymerized, with respect to 1 part by mass of monomer (1).

[0120] In addition, solvates in which various solvents are coordinated are also included in the copolymer X of the present invention. In the present description, examples of the solvate include a hydrate and an ethanolate. The solvent may be coordinated to the copolymer X of the present invention in any number.

[0121] The copolymer X of the present invention can be produced by various known methods. The production method is not particularly limited, and for example, the copolymer X can be produced according to a basic polymer synthesis method described below.

##STR00020##

[0122] In the formula, R represents a hydrogen atom or a C.sub.1-3 alkyl group, and R represents a group represented by R.sup.4, R.sup.5 or R.sup.6.

[0123] This reaction shows a step of producing a polymer (III) by reacting a monomer (I) with a chain transfer agent (II) and an initiator. This reaction can be performed in the absence of a solvent or in a solvent such as alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; N,N-dimethylformamide; N,N-dimethylacetamide; N-methylpyrrolidone; acetonitrile; and ethyl acetate, and it is preferable to use aromatic hydrocarbons such as toluene and xylene as a solvent. As the chain transfer agent, for example, it is possible to use 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT), cyanomethyl dodecyltrithiocarbonate (CDTTC), 2-cyano-2-propyldodecyl trithiocarbonate (CPDTTC), 4-cyano-4-[(dodecylsulfanyl-thiocarbonyl)sulfanyl]pentanoic acid (CDSPA), or 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid 3-azido-1-propanol ester (N.sub.3-CTA), and it is preferable to use DDMAT. Where polymerization is carried out by using a chain transfer agent, the copolymer X of the present invention has a structure in which a part or all of a structure of the chain transfer agent is partially bonded. Where the copolymer X includes a structure of the chain transfer agent, the structure may be removed by an appropriate method. As the initiator, an azo polymerization initiator such as 2,2-azobis-isobutyronitrile (AIBN), 1,1-azobis(cyclohexanecarbonitrile) (ACHN), 2,2-azobis-2-methylbutyronitrile (ANMBN), 2,2-azobis-2,4-dimethylvaleronitrile (ADVN), or dimethyl 2,2-azobis(2-methylpropionate) (MAIB) can be used, and AIBN is preferably used. The reaction temperature is 0 to 300 C., preferably 0 to 150 C., and more preferably 1 to 100 C., and the reaction time is 1 minute to 48 hours, and preferably 5 minutes to 24 hours. In this reaction, a random copolymerized copolymer X can be produced by carrying out the reaction in the coexistence of monomers (I) having different structures.

[0124] The chelating agent bonded to the copolymer X is a molecule having a residue represented by the following formula (a):

##STR00021## [0125] wherein, R.sup.8 represents a hydrogen atom or a hydroxyalkyl group; R.sup.9 and R.sup.10 represent a hydrogen atom or [(CH.sub.2)-L-(CH.sub.2).sub.p]*; X.sup.4 represents an oxygen atom, a sulfur atom, NR.sup.7, or CH.sub.2O; Y and Y represent a hydrogen atom, a methyl group, or a hydroxy group, or Y and Y together represent an oxygen atom; L represents an arylene group, a cycloalkylene group, SS, C(O)O, OC(O), C(O)NH, NHC(O), NHC(O)O, OC(O)NH, or a peptide bond including 1 to 4 amino acid residues; * represents a bond to the copolymer; and o and p independently represent an integer of 0 to 10, and where R.sup.9 is a hydrogen atom, R.sup.10 is [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]*, and where R.sup.9 is [(CH.sub.2).sub.o-L-(CH.sub.2).sub.p]*, R.sup.10 is a hydrogen atom.]

[0126] Examples of the chelating agent include 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A), 1-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,2,3-triacetic acid (HP-DO3A), 10-[1,1,1-tris(hydroxymethyl)methyl]-1,4,7-triscarboxymethyl-1,4,7,10-tetraazacyclododecane (DO3A-butrol), 1,4,7,10-tetraazacyclododecane-N,N,N,N-tetraacetic acid mono-(N-hydroxysuccinimidyl) ester (DOTA-NHS), [(2S,5S,8S,11S)-4,7-bis-carboxymethyl-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclo-dodecan-1-yl]acetic acid (M4DO3A), [(2S,5S,8S,11S)-4,7,10-tris-carboxymethyl-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecane-1-yl]acetic acid (M4DOTA), ,,,-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTMA), (R)-2-[(2S,5S,8S,11S)-4,7,10-tris-((R)-1-carboxyethyl)-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecane-1-yl]propionic acid (M4DOTMA), 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid-10-(2-thioethyl)acetamide (DO3A-Thiol), 5-2-(4-aminobenzyl)-1,4,7,10-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (p-NH.sub.2-Bn-DOTA), 2-methyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (MCTA), diethylenetriaminepentaacetic acid (DTPA), 4-carboxy-5,8,11-tris(carboxymethyl)-1-phenyl-2-oxa-5,8,11-triazatridecane-13-oic acid (BOPTA), ethylenediaminetetraacetic acid (EDTA), 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid (PCTA12), 1,4,8,11-tetraazacyclotetradecane-N,N,N,N-tetraacetic acid (TETA), 1,4,7,10-tetraazacyclotridecane-N,N,N,N-tetraacetic acid (TRITA), 1,5,9,13-tetraazacyclohexadecane-N,N,N,N-tetraacetic acid (HETA), 10-phosphonomethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (MPDO3A), N,N-bis(2-hydroxybenzyl)-ethylenediamine-diacetic acid (HBED), N,N-bis-(2-hydroxyphenylglycine)-ethylenediamine (EHPG), 2-[bis[2-[carboxylatomethyl-[2-(2-methoxyethylamino)-2-oxoethyl]amino]ethyl]amino]acetate (DTPA-BMEA), N-[2-[bis(carboxymethyl)amino]-3-(4-ethoxyphenyl)propyl]-N-[2-[bis(carboxymethyl)amino]ethyl]glycine (EOB-DTPA), N,N-bis[2-[bis(carboxymethyl)amino]ethyl]-L-glutamic acid (DTPA-Glu), N,N-bis[2-[bis(carboxymethyl)amino]ethyl]-L-lysine (DTPA-Lys), N,N-bis[2-[carboxymethyl[(methylcarbamoyl)methyl]amino]-ethyl]glycine (DTPA-BMA), and (+/)-trans-3,10,13,19-tetraazatricyclo[13.3.1.0.sup.4,9]nonadeca-1(19),15,17-triene-3,10,13-triacetic acid (cyclo-PCTA12).

[0127] Examples of the paramagnetic metal ion include a gadolinium ion, a manganese ion, an iron ion, a nickel ion, a cobalt ion, a dysprosium ion, and a terbium ion, and among the ions, the gadolinium ion or the manganese ion is preferable.

[0128] The contrast agent molecule-bonded copolymer of the present invention includes the chelating agent-bonded copolymer and the paramagnetic metal. As the contrast agent molecule, a known MRI contrast agent can be used, and a complex molecule of the paramagnetic metal ion and formula (a) is preferable, Gd-DOTA, GdHP-DO3A, Gd-DO3A-butrol, Gd-DO3A-Thiol, and Gd-DOTA-p-NH2-Bn are more preferable, and Gd-DOTA is particularly preferable.

[0129] A salt of the contrast agent molecule-bonded copolymer of the present invention is not particularly limited as long as the salt is a pharmaceutically acceptable salt. Examples of such salt include alkali metal salts such as a sodium salt and a potassium salt, salts with metals of Group 2 elements such as a calcium salt and a magnesium salt, organic amine salts such as a phenethylamine salt, and ammonium salts.

[0130] Where geometric isomers or optical isomers are present in the contrast agent molecule-bonded copolymer of the present invention, mixtures or separations of those isomers are also included in the scope of the present invention. Separation of the isomers can be performed by a conventional method.

[0131] The contrast agent molecule-bonded copolymer of the present invention can be produced by various known methods. The production method is not particularly limited, and for example, the contrast agent molecule-bonded copolymer can be produced according to a synthesis method described below.

##STR00022##

[0132] In the formula, R, R, X.sup.4, Y, Y, or L represents a similar group as described above, and P.sub.1 or P.sub.2 represents a protecting group.

[0133] This reaction refers to a process of producing a chelating agent-bonded copolymer (VI) by reacting the copolymer (III) with a linker (IV) and a chelating agent (V) in a solvent or without a solvent, in the presence of a condensing agent and in the presence or absence of a reaction accelerator.

[0134] The solvent is not particularly limited, and this reaction can be performed in a solvent, for example, alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as dichloromethane, chloroform, and 1,2-dichloroethane; N,N-dimethylformamide; N,N-dimethylacetamide; N-methylpyrrolidone; acetonitrile; and ethyl acetate. It is preferable to use an aprotic polar solvent such as tetrahydrofuran, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, or ethyl acetate.

[0135] The linker is not particularly limited as long as the linker can link the copolymer and the chelating agent, and examples thereof include ethylenediamine, N-Boc-ethylenediamine, 1,3-propanediamine, N-Boc-1,3-propanediamine, 1,4-butanediamine, N-Boc-1,4-butanediamine, 1,5-pentanediamine, N-Boc-1,5-pentanediamine, 1,6-hexanediamine, N-Boc-1,6-hexanediamine, 1,7-heptanediamine, N-Boc-1,7-heptanediamine, 1,8-octanediamine, N-Boc-1,8-octanediamine, 1,9-nonanediamine, N-Boc-1,9-nonanediamine, 1,10-decanediamine, N-Boc-1,10-decanediamine, 2-aminoethanol, 2-(Boc-amino)-1-ethanol, 3-amino-1-propanol, 3-(Boc-amino)-1-propanol, 4-amino-1-butanol, 4-(Boc-amino)-1-butanol, 5-amino-1-pentanol, 5-(Boc-amino)-1-pentanol, 6-amino-1-hexanol, 6-(Boc-amino)-1-hexanol, 7-(Boc-amino)-1-heptanol, 8-(Boc-amino)-1-octanol, 9-(Boc-amino)-1-nonanol, 10-(Boc-amino)-1-decanol, glycolic acid, tert-butyl glycolate, 3-hydroxypropionic acid, tert-butyl 3-hydroxypropanoate, 4-hydroxybutyric acid, tert-butyl 4-hydroxybutanoate, cystamine, N-Boc-cystamine, 6-maleimidohexanoic acid N-succinimidyl ester, 4-maleimidobutyric acid N-succinimidyl ester, 3-maleimidopropionic acid N-succinimidyl ester, 3-(2-pyridyldithio)propionic acid N-succinimidyl ester, 4-(N-maleimidomethyl)cyclohexanecarboxylate N-succinimidyl ester, (S)-2-[(S)-2-amino-3-methylbutanamido]-N-[4-(hydroxymethyl)phenyl]-5-ureidopentanamide, [(S)-1-[[(S)-1-[[4-(hydroxymethyl)phenyl]amino]-1-oxo-5-ureidopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]carbamic acid (9H-fluoren-9-yl)methyl ester, [(S)-1-[[(S)-1-[[4-(hydroxymethyl)phenyl]amino]-1-oxo-5-ureidopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]carbamic acid allyl ester, 6-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)-N[(S)-1-[[(S)-1-[[4-(hydroxymethyl)phenyl]amino]-1-oxo-5-ureidopentan-2-yl]amino]-3-methyl-1-oxobutan-2-yl]hexanamide, -alanine, -alanine tert-butyl ester, and a pharmaceutically acceptable salt thereof, and N-Boc-ethylenediamine, 2-(Boc-amino)-1-ethanol, tert-butyl glycolate, and N-Boc-cystamine are preferable.

[0136] Where the chelating agent includes a functional group linkable to the copolymer X in its structure, it is also possible to directly link the copolymer and the chelating agent without interposing the linker.

[0137] The protecting group represented by P.sub.1 and P.sub.2 is not particularly limited, and can be selected with reference to, for example, a literature (Protective Groups in Organic Synthesis Fifth Edition, John Wiley & Sons, Inc.).

[0138] Examples of the condensing agent include carbodiimide reagents such as dicyclohexylcarbodiimide (DCC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (WSC-HCl), and diisopropylcarbodiimide (DIPCDI), and phosphonium salt type or guanidinium salt type reagents such as (1H-benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP), (1H-benzotriazol-1-yloxy)tris(pyrrolidino)phosphonium hexafluorophosphate (PyBOP), 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo(4,5-b)pyridinium-3-oxide hexafluorophosphate (HATU), (1-cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate (COMU), chloro-N,N,N,N-tetramethylformamidinium hexafluorophosphate (TCFH), 1-[bis(dimethylamino)methylene]-1H-benzotriazolium-3-oxide hexafluorophosphate (HBTU), 1-[bis(dimethylamino)methylene]-1H-benzotriazolium-3-oxide tetrafluoroborate (TBTU), 1-[bis(dimethylamino)methylene]-5-chloro-1H-benzotriazolium-3-oxide hexafluorophosphate (HCTU), and 1-[bis(dimethylamino)methylene]-5-chloro-1H-benzotriazolium-3-oxide tetrafluoroborate (TCTU), and among the reagents, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (WSC-HCl), (1H-benzotriazol-1-yloxy)tris(pyrrolidino)phosphonium hexafluorophosphate (PyBOP), 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo(4,5-b)pyridinium-3-oxodohexafluorophosphate (HATU), (1-cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate (COMU), and chloro-N,N,N,N-tetramethylformamidinium hexafluorophosphate (TCFH) are preferable.

[0139] Examples of the reaction accelerator include triethylamine, diisopropylethylamine, pyridine, lutidine, picoline, N,N-dimethylaminopyridine (DMAP), 1-methylimidazole, 2,2,6,6-tetramethylpiperidine (TMP), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), N-methylmorpholine (NMM), 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), 1-hydroxybenzotriazole (HOBt), 6-chloro-1-hydroxybenzotriazole (6-Cl-HOBt), 3,4-dihydro-3-hydroxy-4-oxo-1,2,3-benzotriazine (HOOBt), and 1-hydroxy-7-azabenzotriazole (HOAt), and among the reaction accelerators, diisopropylethylamine, N,N-dimethylaminopyridine (DMAP), 1-methylimidazole, 2,2,6,6-tetramethylpiperidine (TMP), and 1,8-diazabicyclo[5.4.0]-7-undecene (DBU) are preferable.

[0140] The reaction temperature may be from 0 C. to 100 C., preferably from 1 to 80 C., and the reaction time may be from 5 minutes to 1 week, and preferably from 2 hours to 3 days. To smoothly advance the reaction, the reaction may be performed under a nitrogen stream or an argon stream.

##STR00023##

[0141] In the formula, R, R, X.sup.4, Y, Y, or L represents a similar group as described above, and M represents a paramagnetic metal ion.

[0142] This reaction refers to a process of producing a contrast agent molecule-bonded copolymer (VII) by reacting a chelating agent-bonded polymer (VI) with a paramagnetic metal ion (M).

[0143] This reaction can be performed in water or in a solvent, for example, alcohols such as methanol, ethanol, 1-propanol, and 2-propanol; an aprotic polar solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, or ethyl acetate, and is preferably performed in water. The paramagnetic metal ion is not particularly limited as long as the ion has coordination ability to the chelating agent, and it is possible to use, for example, Fe(2+), Fe(3+), Cu(2+), Ni(2+), Rh(2+), Co(2+), Cr(3+), Gd(3+), Eu(3+), Dy(3+), Tb(3+), Pm(3+), Nd(3+), Tm(3+), Ce(3+), Y(3+), Ho(3+), Er(3+), La(3+), Yb(3+), Mn(3+), or Mn(2+), and it is preferable to use Gd(3+) or Mn(2+). The reaction temperature may be from 0 to 300 C., preferably from 0 to 150 C., and more preferably from 1 to 100 C., and the reaction time may be from 1 minute to 48 hours, and preferably from 5 minutes to 24 hours.

[0144] The produced polymer X and contrast agent molecule-bonded copolymer of the present invention can be purified by a polymer isolation and purification method generally known in the field of polymer chemistry. Specific examples thereof include treatment operations such as extraction, recrystallization, salting out using, for example, ammonium sulfate or sodium sulfate, centrifugation, dialysis, ultrafiltration, adsorption chromatography, ion exchange chromatography, hydrophobic chromatography, normal phase chromatography, reverse phase chromatography, gel filtration, gel permeation chromatography, affinity chromatography, electrophoresis, countercurrent distribution, and combinations thereof.

[0145] The copolymer X and the contrast agent molecule-bonded copolymer of the present invention can be utilized as carriers for transporting various drugs (contrast agents). For example, a pharmaceutical composition including the contrast agent molecule-bonded copolymer in which the contrast agent is loaded into (contained in) the copolymer X of the present invention can be used as a contrast agent and/or a diagnostic drug for various cancer diseases such as a colon cancer, a duodenal cancer, a gastric cancer, a pancreatic cancer, a liver cancer, a lung cancer, a uterine cancer, an ovarian cancer, and brain tumors because the tumor accumulation ability is high, as confirmed in test examples described later.

[0146] When the copolymer and the contrast agent molecule-bonded copolymer of the present invention are used as a drug transport carrier, the dose and the number of doses may be appropriately selected in consideration of, for example, administration form, age and body weight of a patient, and nature or severity of a symptom to be treated, and the dose and the number of doses should not be limited. However, when a polymer encapsulating a drug is intravenously injected by an injection, for example, for an adult (60 kg), a single dose is preferably administered in an amount of 0.12 mg to 12,000,000 mg, more preferably 1.2 mg to 1,200,000 mg, and particularly preferably 12 to 120 000 mg.

[0147] The pharmaceutical composition of the present invention can be produced by mixing the copolymer X of the present invention with the contrast agent molecule. Further, the pharmaceutical composition can also be produced by mixing the copolymer X of the present invention with the chelating agent molecule and then with the paramagnetic metal. Preferably, the single chain nanoparticle may be produced using the contrast agent molecule-bonded copolymer of the present invention, or the single chain nanoparticle of the copolymer X of the present invention may be produced and then mixed with the contrast agent molecule. The single chain nanoparticle can be produced by a known method.

[0148] In the pharmaceutical composition of the present invention, the contrast agent molecule may be loaded into the copolymer X or the contrast agent molecule-bonded copolymer by the action such as electrostatic interaction, hydrogen bond, hydrophobic interaction, or covalent bond.

[0149] A route of administration of the pharmaceutical composition of the present invention is desirably the most effective one for treatment, and the pharmaceutical composition can be administered by a parenteral administration preparation such as an oral administration preparation, an injection, or a transdermal administration preparation. For example, parenteral administration such as intraarterial injection, intravenous injection, subcutaneous injection, intramuscular injection, or intraperitoneal injection is preferable, and intraarterial injection and intravenous injection are more preferable. The number of doses should not be limited, and examples thereof include one to several doses per week average.

[0150] Various preparations suitable for the route of administration can be produced by a conventional method by appropriately selecting preparation additives such as excipients, extenders, binders, wetting agents, disintegrants, lubricants, surfactants, dispersants, buffers, preservatives, solubilizing agents, antiseptics, flavoring agents, soothing agents, stabilizers, and isotonizing agents that are conventionally used in formulation.

[0151] The preparation additives that can be contained in the various preparations described above are not particularly limited as long as the preparation additives are pharmaceutically acceptable. Examples of such preparation additives include purified water, water for injection, distilled water for injection, pharmaceutically acceptable organic solvents, collagen, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, sodium alginate, water-soluble dextran, sodium carboxymethyl starch, pectin, xanthan gum, gum arabic, casein, gelatin, agar, glycerin, propylene glycol, polyethylene glycol, petrolatum, paraffin, stearyl alcohol, stearic acid, human serum albumin, mannitol, sorbitol, and lactose. Additives to be used are appropriately selected according to various preparations, and can be used alone or in combination.

[0152] The injection can also be prepared as a non-aqueous diluent (for example, polyethylene glycol, vegetable oils such as olive oil, and alcohols such as ethanol), a suspension, or an emulsion. Sterilization of the injection can be performed by filtration sterilization using a filter, and blending of, for example, a microbicide. In addition, the injection can be produced in a form of preparation before use. That is, the injection can be formed into a sterile solid composition by, for example, lyophilization, and can be dissolved in water for injection, distilled water for injection, or another solvent before use.

EXAMPLES

[0153] Hereinafter, the present invention will be described more specifically with reference to examples. These examples are provided for purpose of exemplification and are not intended to limit embodiments of the invention.

[Example 1] Production of poly[(benzyl acrylate)-co-(poly(ethylene glycol)methyl ether acrylate)-co-(1-ethoxyethyl Acrylate)]

(1) Synthesis of 1-Ethoxyethyl Acrylate (EEA)

[0154] Ethyl vinyl ether (28.725 mL) was weighed under an argon atmosphere, and thereto was added a phosphoric acid (50 mg) under ice cooling. Thereto was added acrylic acid (17.15 mL), and the mixture was stirred at room temperature for 48 hours. Further thereto was added hydrotalcite (3 g), and the mixture was stirred for 2 hours, and the reaction was stopped. After celite filtration, unreacted ethyl vinyl ether was removed by evaporation. Thereto was added phenothiazine (up to 500 ppm) as a polymerization inhibitor, and the mixture was purified by distillation under reduced pressure together with calcium hydride (distillation temperature of 28 to 32 C.). The obtained 1-ethoxyethyl acrylate was dispensed into a glass vial and stored at 30 C.

[0155] .sup.13C NMR (400 MHz, CDCl.sub.3), , ppm: 15.29 (OCH.sub.2CH.sub.3), 21.16 (COOCH(CH.sub.3)), 64.98 (OCH.sub.2), 96.73 (COOCH(CH.sub.3)), 128.84 (CH.sub.2CH), 131.43 (CH.sub.2CH), 166.00 (COO).

(2) Synthesis of poly[(benzyl acrylate)-co-(poly(ethylene glycol) methyl ether acrylate)-co-(1-ethoxyethyl Acrylate)]

[0156] 100 mg of 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) was weighed and dissolved in 17.3 mL of toluene to prepare a DDMAT/toluene stock solution (5.78 mg/mL as a DDMAT concentration). Similarly, 22 mg of 2,2-azobis(2-methylpropionitrile) (AIBN) was weighed and dissolved in 17.3 mL of toluene to prepare an AIBN/toluene stock solution (AIBN concentration: 1.27 mg/mL). Separately, 1.296 g of poly(ethylene glycol) methyl ether acrylate (mPEGA, the average value (n) of the numbers of repetitions of ethylene glycol is 9), 0.394 g of benzyl acrylate (BnA), 0.039 g of 1-ethoxyethyl acrylate, 1.73 mL of a DDMAT/toluene stock solution, and 1.73 mL of an AIBN/toluene stock solution were added, and polymerization was performed in an oil bath at 70 C. After a lapse of 90 minutes, the polymerization was stopped, and then the reaction solution was subjected to a reprecipitation method or dialyzed against methanol to recover the copolymer. Since the obtained copolymer was basically a viscous body, in the reprecipitation method, an operation of dropping the reaction solution into a centrifuge tube to which a poor solvent (hexane/ethyl acetate=7/3 [v/v]) was added and recovering the solution by centrifugation (2,000g, 5 min) was repeated 3 times, and finally vacuum drying was performed to obtain 1.223 g of poly[(benzyl acrylate)-co-(poly(ethylene glycol) methyl ether acrylate)-co-(1-ethoxyethyl acrylate)]. As a result of analyzing the polymerization degree of each monomer and the number average molecular weight (M.sub.n,NMR) from a .sup.1H-NMR spectrum of the obtained copolymer measured using NMR, the polymerization degree of mPEGA (n=9) was 102, the polymerization degree of BnA was 94, the polymerization degree of EEA was 9, and M.sub.n,NMR was 65,900. The molecular weight dispersion (M.sub.w/M.sub.n) of the obtained copolymer was measured using GPC, and as a result, it was found to be 1.53.

##STR00024##

[Measurement Apparatus and Conditions]

(1) .SUP.1.H-NMR Measurement

[0157] Apparatus: JNM-ECX 400 (400 MHz)/JEOL Ltd. [0158] Solvent: Dimethyl sulfoxide-d.sub.6 containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0159] Sample concentration: 20 mg/mL [0160] Measurement temperature: 25 C. [0161] Number of integration times: 256 times [0162] Result: FIG. 1

(2) GPC Measurement

[0163] Apparatus: HPLC-Prominence system/SHIMADZU CORPORATION [0164] Detector: RID-10A Refractive index detector/SHIMADZU CORPORATION [0165] Column: TSKgel -2500 column/Tosoh Corporation [0166] (Column size: 7.8 mm300 mm, particle diameter: 7 m, exclusion limit molecular weight: 510.sup.3) [0167] TSKgel -4000 column/Tosoh Corporation [0168] (Column size: 7.8 mm00 mm, particle diameter: 10 m, exclusion limit molecular weight: 410.sup.5) [0169] TSKgel guardcolum/Tosoh Corporation [0170] Mobile phase: N,N-dimethyformamide (DMF) containing 10 mmol/L lithium bromide [0171] Temperature: 40 C. [0172] Flow rate: 0.5 mL/min [0173] Sample concentration: 6 mg/mL [0174] Standard substance: Poly(methyl methacrylate) standard ReadyCal set, M.sub.p 800-2,200,000 Da/SIGMA [0175] Result: FIG. 2

TABLE-US-00001 TABLE 1 Composition ratio (molar ratio to chain transfer agent) Chain Polymerization transfer Monomer Temper- Poly- degree agent Initiator mPEGA ature merization Yield mPEGA Example DDMAT AlBN n = 9 BnA EEA Solvent ( C.) time (min) (g) n = 9 BnA EEA M.sub.n, NMR M.sub.w/M.sub.n 1 1 0.5 100 90 10 Toluene 70 90 1.223 102 94 9 65 900 1.53

Examples 2 to 68

[0176] Polymers having different composition ratios and average molecular weights shown in the following table were produced by appropriately changing the type, charged amount, reaction temperature, and polymerization time of the monomers (mPEGA, BnA, and EEA) used in Example 1, and using the same method as in Example 1.

TABLE-US-00002 TABLE 2 Composition ratio (molar ratio to chain transfer agent) Monomer Chain 2-Hydroxy- transfer 2-Hydroxy 4-Hydroxy 3-phenoxy Temper- Poly- agent Initiator mPEGA ethyl butyl propyl ature merization Example DDMAT AlBN ACHN n = 4 n = 9 n = 22 BnA EEA acrylate acrylate acrylate Solvent ( C.) time (min) 2 1 2 255 15 30 Toluene 70 90 3 1 2 160 20 20 Toluene 70 60 4 1 2 240 30 30 Toluene 70 60 5 1 2 170 10 20 Toluene 70 60 6 1 2 255 15 30 Toluene 70 60 7 1 0.5 16 16 8 Toluene 70 90 8 1 0.5 18 14 8 Toluene 70 90 9 1 0.5 20 12 8 Toluene 70 90 10 1 0.5 20 12 8 Toluene 70 90 11 1 0.5 20 12 8 Toluene 70 90 12 1 0.5 20 16 4 Toluene 70 10 13 1 0.5 20 16 4 Toluene 70 30 14 1 0.5 20 16 4 Toluene 70 50 15 1 0.5 20 16 4 Toluene 70 70 16 1 0.5 20 16 4 Toluene 70 90 17 1 0.5 22 10 8 Toluene 70 90 18 1 0.5 24 8 8 Toluene 70 90 19 1 0.5 24 8 8 Toluene 70 90 20 1 0.5 28 4 8 Toluene 70 90 21 1 0.5 10 25 15 Toluene 70 90 22 1 0.5 17 25 8 Toluene 70 90 23 1 0.5 22.5 12.5 15 Toluene 70 90 24 1 0.5 25 20 5 Toluene 70 90 25 1 0.5 29.5 12.5 8 Toluene 70 90 26 1 0.5 30 24 6 Toluene 70 90 27 1 0.5 35 28 7 Toluene 70 90 28 1 0.5 50 40 10 Toluene 70 90 29 1 0.5 10 10 180 Toluene 70 90 30 1 0.5 30 30 140 Toluene 70 90 31 1 0.5 30 70 100 Toluene 70 90 32 1 0.5 30 110 60 Toluene 70 90 33 1 0.5 50 10 140 Toluene 70 90 34 1 0.5 50 50 100 Toluene 70 90 35 1 0.5 50 90 60 Toluene 70 90 36 1 0.5 50 130 20 Toluene 70 90 37 1 0.5 70 30 100 Toluene 70 90 38 1 0.5 70 70 60 Toluene 70 90 39 1 0.5 70 110 20 Toluene 70 90 40 1 0.5 80 80 40 Toluene 70 90 41 1 0.5 80 100 20 Toluene 70 90 42 1 0.5 90 10 100 Toluene 70 90 43 1 0.5 90 50 60 Toluene 70 90 44 1 0.5 90 90 20 Toluene 70 90 45 1 0.5 100 20 80 Toluene 70 90 46 1 0.5 100 40 60 Toluene 70 90 47 1 0.5 100 50 50 Toluene 70 90 48 1 0.5 100 60 40 Toluene 70 90 49 1 0.5 100 70 30 Toluene 70 90 50 1 0.5 100 80 20 Toluene 70 90 51 1 0.5 110 30 60 Toluene 70 90 52 1 0.5 110 70 20 Toluene 70 90 53 1 0.5 130 10 60 Toluene 70 90 54 1 0.5 130 50 20 Toluene 70 90 55 1 0.5 150 30 20 Toluene 70 90 56 1 0.5 170 10 20 Toluene 70 90 57 1 0.5 200 160 40 Toluene 70 90 58 1 0.5 300 240 60 Toluene 70 90 59 1 0.5 400 320 80 Toluene 70 90 60 1 2 105 155 40 Toluene 70 90 61 1 2 120 240 40 Toluene 70 90 62 1 2 140 210 50 Toluene 70 90 63 1 2 140 220 40 Toluene 70 90 64 1 0.1 100 80 20 1,4- 70 90 dioxane 65 1 0.5 100 50 50 1,4- 70 180 dioxane 66 1 0.5 100 80 20 1,4- 70 180 dioxane 67 1 0.1 130 65 65 1,4- 70 90 dioxane 68 1 0.1 130 104 26 1,4- 70 90 dioxane

TABLE-US-00003 TABLE 3 Polymerization degree 2-Hydroxy- 2-Hydroxy 4-Hydroxy 3-phenoxy mPEGA ethyl butyl propyl Example n = 4 n = 9 n = 22 BnA EEA acrylate acrylate acrylate M.sub.n, NMR M.sub.w/M.sub.n 2 250 18 31 62 400 1.37 3 155 22 20 39 200 1.23 4 211 29 29 53 100 1.32 5 162 11 20 39 000 1.22 6 227 15 28 54 300 1.33 7 16 16 8 11 800 1.20 8 18 14 8 12 400 1.20 9 13 8 5 8 600 1.46 10 20 13 8 13 400 1.30 11 18 11 7 11 700 1.33 12 8 7 1 5 300 1.51 13 16 13 3 10 800 1.30 14 19 15 3 12 200 1.28 15 20 16 4 13 300 1.39 16 24 19 4 15 700 1.29 17 21 10 8 13 200 1.20 18 13 5 4 8 000 1.44 19 24 8 8 14 300 1.21 20 26 4 8 14 600 1.20 21 7 17 9 8 100 1.41 22 11 17 5 9 200 1.39 23 15 9 10 10 700 1.30 24 26 21 5 16 900 1.31 25 20 10 6 12 400 1.33 26 33 27 6 21 500 1.34 27 39 30 7 25 000 1.36 28 39 4 8 20 200 1.25 29 10 10 159 29 700 1.19 30 27 27 122 35 600 1.27 31 30 66 91 38 600 1.17 32 27 91 52 35 800 1.20 33 45 10 123 41 000 1.31 34 44 45 86 41 100 1.20 35 45 79 54 42 700 1.24 36 43 111 19 42 000 1.28 37 60 28 87 46 500 1.24 38 55 57 49 43 000 1.27 39 56 89 18 44 300 1.30 40 79 80 36 56 400 1.43 41 81 106 17 58 900 1.51 42 81 12 93 54 600 1.27 43 71 42 51 48 600 1.30 44 70 73 18 48 400 1.32 45 84 19 72 54 200 1.33 46 80 35 52 51 900 1.35 47 84 45 44 54 200 1.33 48 82 52 35 53 100 1.36 49 94 68 26 60 100 1.50 50 104 83 20 66 700 1.52 51 93 30 55 57 700 1.33 52 84 56 18 52 400 1.35 53 105 10 52 60 000 1.35 54 102 42 18 58 900 1.37 55 111 25 18 60 100 1.40 56 131 10 18 67 400 1.43 57 129 108 31 84 100 1.51 58 170 144 40 111 200 1.61 59 221 191 50 144 700 1.68 60 58 102 78 91 200 1.71 61 62 143 21 93 100 1.68 62 59 105 93 95 000 1.82 63 60 106 18 85 400 1.68 64 75 66 19 49 400 1.46 65 67 37 39 44 300 1.40 66 61 56 20 41 600 1.43 67 75 42 42 52 300 1.61 68 75 68 18 51 400 1.56

Example 69

[0177] 110 mg of 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) was weighed and dissolved in 19.0 mL of toluene to prepare a DDMAT/toluene stock solution (5.78 mg/mL as a DDMAT concentration). Similarly, 25 mg of 2,2-azobis(2-methylpropionitrile) (AIBN) was weighed and dissolved in 19.7 mL of toluene to prepare an AIBN/toluene stock solution (AIBN concentration: 1.27 mg/mL). Separately, 12.96 g of poly(ethylene glycol) methyl ether acrylate (mPEGA, the average value (n) of the numbers of repetitions of ethylene glycol is 9), 3.50 g of benzyl acrylate (BnA), 0.78 g of 1-ethoxyethyl acrylate, 17.3 mL of a DDMAT/toluene stock solution, and 17.3 mL of an AIBN/toluene stock solution were added, and polymerization was performed in an oil bath at 70 C. After a lapse of 90 minutes, the polymerization was stopped, and then the reaction solution was subjected to a reprecipitation method or dialyzed against methanol to recover the copolymer. Since the obtained copolymer was basically a viscous body, in the reprecipitation method, an operation of dropping the reaction solution into a centrifuge tube to which a poor solvent (hexane/ethyl acetate=7/3 [v/v]) was added and recovering the solution by centrifugation (2,000g, 5 min) was repeated 3 times, and finally the vacuum drying was performed. By treating obtained copolymer with 0.5N HCl at room temperature, an ethoxyethyl group was eliminated to obtain 12.41 g of poly[(benzyl acrylate)-co-(poly(ethylene glycol)methyl ether acrylate)-co-(acrylic acid)].

[0178] As a result of analyzing a polymerization degree of each monomer and a number average molecular weight (M.sub.n,NMR) of the obtained copolymer from a .sup.1H-NMR spectrum measured by using NMR, the polymerization degree of mPEGA (n=9) was 88, the polymerization degree of BnA was 75, the polymerization degree of EEA was 17, and M.sub.n,NMR was 57,200. Moreover, a molecular weight dispersion (M.sub.w/M.sub.n) of the obtained copolymer was measured by using the GPC and a result thereof was 1.51.

##STR00025##

[Measurement Apparatuses and Conditions]

(1) .SUP.1.H-NMR Measurement

[0179] Apparatus: JNM-ECX400 (400 MHz)/JEOL Ltd. [0180] Solvent: dimethyl sulfoxide-d.sub.6 containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0181] Sample concentration: 20 mg/mL [0182] Measurement temperature: 25 C. [0183] Number of integration times: 256 times [0184] Results: FIG. 3

(2) GPC Measurement

[0185] Apparatus: HPLC-Prominence system/SHIMADZU CORPORATION [0186] Detector: RID-10A Refractive index detector/SHIMADZU CORPORATION [0187] Column: TSKgel -2500 column/Tosoh Corporation [0188] (Column size: 7.8 mm300 mm, particle diameter: 7 m, and exclusion limit molecular weight: 510.sup.3) [0189] TSKgel -4000 column/Tosoh Corporation [0190] (Column size: 7.8 mm300 mm, particle diameter: 10 m, and exclusion limit molecular weight: 410.sup.5) [0191] TSKgel guardcolum/Tosoh Corporation [0192] Mobile phase: N,N-dimethyformamide (DMF) containing 10 mmol/L of lithium bromide [0193] Temperature: 40 C. [0194] Flow rate: 0.5 mL/min [0195] Sample concentration: 6 mg/mL [0196] Standard substance: poly(methyl methacrylate) standard ReadyCal set, M.sub.p 800-2,200,000 Da/SIGMA [0197] Results: FIG. 4

TABLE-US-00004 TABLE 4 Composition ratio (molar ratio to chain transfer agent) Chain transfer Monomer Temper- Poly- Polymerization degree agent Initiator mPEGA ature merization Yield mPEGA Example DDMAT AlBN n = 9 BnA EEA Solvent ( C.) time (g) n = 9 BnA EEA M.sub.n, NMR M.sub.w/M.sub.n 69 1 0.5 100 80 20 Toluene 70 90 12.41 88 75 17 57 200 1.51

Examples 70 to 97

[0198] Polymers having different composition ratios and average molecular weights as shown in the following table were produced by appropriately changing charged amounts and polymerization times of the monomers (mPEGA, BnA, and EEA) used in Example 69, by the same method as Example 69.

TABLE-US-00005 TABLE 5 Composition ratio (molar ratio to chain transfer agent) Chain transfer Monomer agent Initiator mPEGA Temperature Polymerization Example DDMAT AlBN (n = 9) BnA EEA Solvent ( C.) time (min) 70 1 0.5 16 10 6 Toluene 70 30 71 1 0.5 10 25 15 Toluene 70 95 72 1 0.5 17 25 8 Toluene 70 95 73 1 0.5 22.5 12.5 15 Toluene 70 95 74 1 0.5 25 10 15 Toluene 70 60 75 1 0.5 25 12.5 12.5 Toluene 70 120 76 1 0.5 29.5 12.5 8 Toluene 70 95 77 1 0.5 32.5 13 19.5 Toluene 70 100 78 1 0.5 40 16 24 Toluene 70 100 79 1 0.5 40 20 20 Toluene 70 100 80 1 0.5 50 20 30 Toluene 70 100 81 1 0.5 50 25 25 Toluene 70 100 82 1 0.5 75 30 45 Toluene 70 100 83 1 0.5 75 37.5 37.5 Toluene 70 100 84 1 0.5 50 10 140 Toluene 70 90 85 1 0.5 50 50 100 Toluene 70 90 86 1 0.5 50 90 60 Toluene 70 90 87 1 0.5 70 70 60 Toluene 70 90 88 1 0.5 70 110 20 Toluene 70 90 89 1 0.5 80 100 20 Toluene 70 90 90 1 0.5 90 90 20 Toluene 70 90 91 1 0.5 100 20 80 Toluene 70 90 92 1 0.5 100 40 60 Toluene 70 90 93 1 0.5 100 50 50 Toluene 70 90 94 1 0.5 100 60 40 Toluene 70 90 95 1 0.5 100 90 10 Toluene 70 90 96 1 0.5 200 160 40 Toluene 70 90 97 1 0.5 400 320 80 Toluene 70 90

TABLE-US-00006 TABLE 6 Polymerization degree Monomer mPEGA EEA Example (n = 9) BnA (Acrylic acid) M.sub.n, NMR M.sub.w/M.sub.n 70 13 8 5 8 200 1.29 71 7 17 9 7 400 1.41 72 11 17 5 8 800 1.39 73 15 9 10 10 000 1.30 74 18 8 11 11 000 1.34 75 19 11 10 11 900 1.37 76 20 10 6 12 000 1.33 77 33 14 18 19 700 1.13 78 40 18 25 24 100 1.14 79 39 22 21 24 300 1.14 80 48 21 30 28 800 1.16 81 49 27 27 30 100 1.16 82 67 29 42 40 100 1.21 83 69 37 37 42 000 1.22 84 45 10 123 32 200 1.31 85 44 45 86 34 900 1.20 86 45 79 54 38 800 1.24 87 55 57 49 39 400 1.27 88 56 89 18 43 000 1.30 89 81 106 17 57 700 1.51 90 70 73 18 47 200 1.32 91 84 19 72 49 000 1.32 92 80 35 52 48 100 1.34 93 84 45 44 51 000 1.33 94 82 52 35 50 600 1.36 95 102 94 9 65 200 1.58 96 129 108 31 81 900 1.51 97 221 191 50 141 100 1.68

Example 98

End Structure Conversion of Terpolymer

[0199] In toluene (70 mL), the copolymer obtained in Example 69 (7.00 g) was dissolved. To this solution, AIBN (411 mg) and lauroyl peroxide (100 mg) were added, and the mixture was stirred in a hot water bath at 80 C. overnight. After the reaction was stopped by ice cooling, the copolymer was recovered by subjecting the reaction solution to reprecipitation method or dialyzed against methanol. Since the obtained copolymer was basically a viscous body, in the reprecipitation, an operation of dropping the reaction solution into a centrifuge tube to which the poor solvent (hexane/ethyl acetate=7/3 [v/v]) was added and recovering the solution by centrifugation (2,000g, 5 min) was repeated three times, and finally the vacuum drying was performed to obtain a terpolymer with a converted end structure (6.25 g).

[0200] A residual ratio of the end structure of the obtained copolymer was evaluated based on an absorbance of a peak derived from a trithiocarbonate group (wavelength: 309 nm) in a UV spectrum measured by using an ultraviolet-visible spectrophotometer, and a result thereof was 0.0%.

##STR00026##

[Measurement Apparatuses and Conditions]

(1) UV Spectrum Measurement

[0201] Apparatus: Hitachi spectrophotometer U-9300/Hitachi, Ltd. [0202] Solvent: purified water [0203] Sample concentration: 4 mg/mL [0204] Measurement wavelength: 250 to 500 nm [0205] Results: FIG. 5

TABLE-US-00007 TABLE 7 Azo compound Residual ratio of Example Copolymer used used in reaction end structure (%) 98 Example 69 AlBN 0.0

Examples 99 to 105

[0206] Copolymers having different end structures as shown in the following table were synthesized by appropriately changing a type and a charged amount of the azo compound for the copolymers obtained in Examples 70 to 97 by the same method as Example 98.

TABLE-US-00008 TABLE 8 Azo compound Residual ratio of Example Copolymer used used in reaction end structure (%) 99 Example 70 AlBN 0.0 100 Example 74 AlBN 0.0 101 Example 82 AlBN 0.0 102 Example 92 AlBN 3.6 103 Example 93 AlBN 0.0 104 Example 82 MAlB 0.0 105 Example 93 MAlB 0.0

Example 106

Synthesis of Chelating Agent-Bonded Copolymer (Disulfide Bond)

[0207] In DMF (13 mL), the copolymer obtained in Example 98 (650 mg) was dissolved, (1-cyano-2-ethoxy-2-oxoethylideneaminooxy)dimethylaminomorpholinocarbenium hexafluorophosphate (COMU) (166 mg) and 2,2,6,6-tetramethylpiperidine (TMP) (66 L) were added, and the mixture was stirred at room temperature for 3 hours. Thereto was added Boc-cystamine hydrochloride (280 mg), and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of dichloromethane (DCM) and trifluoroacetic acid (TFA) [DCM/TFA=5/3 (v/v)] (10 mL), and the mixture was stirred at room temperature overnight to perform deprotection. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. In DMF (21 mL), the obtained copolymer (534 mg) was dissolved, DOTA-tris(t-Bu ester) (387 mg), COMU (289 mg), and TMP (114 L) were added, and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)](32 mL) and the mixture was stirred at room temperature overnight to perform carboxyl group deprotection, and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to obtain the chelating agent-bonded copolymer (disulfide linker) (557 mg).

##STR00027##

[0208] For the chelating agent-bonded copolymer (disulfide linker) before the carboxyl group deprotection, the number of the chelating agent introduced to one molecule of the copolymer was analyzed from a .sup.1H-NMR spectrum measured by using NMR, and a result thereof was 11 mol/mol.

[Measurement Apparatuses and Conditions]

(1) .SUP.1.H-NMR Measurement

[0209] Apparatus: JNM-ECX400 (400 MHz)/JEOL Ltd. [0210] Solvent: dimethyl sulfoxide-d.sub.6 containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0211] Sample concentration: 20 mg/mL [0212] Measurement temperature: 25 C. [0213] Number of integration times: 256 times [0214] Results: FIG. 6

TABLE-US-00009 TABLE 9 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 106 Example 98 11

Examples 107 to 133

[0215] For the copolymers obtained in Examples 69 to 105, copolymers having different numbers of the chelating agent introduced to one molecule of each copolymer as shown in the following table were synthesized by appropriately changing charged amounts of the linker and the chelating agent by the same method as Example 106.

TABLE-US-00010 TABLE 10 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 107 Example 69 11 108 Example 70 2 109 Example 74 4 110 Example 75 4 111 Example 78 10 112 Example 79 8 113 Example 80 13 114 Example 81 12 115 Example 82 19 116 Example 83 18 117 Example 84 28 118 Example 85 29 119 Example 86 22 120 Example 87 20 121 Example 88 10 122 Example 90 10 123 Example 91 30 124 Example 92 23 125 Example 93 25 126 Example 94 19 127 Example 99 3 128 Example 100 5 129 Example 101 10 130 Example 102 28 131 Example 103 25 132 Example 104 12 133 Example 105 18

Example 134

Synthesis of Chelating Agent-Bonded Copolymer (Amide Bond 1)

[0216] In DMF (16 mL), the copolymer obtained in Example 69 (400 mg) was dissolved, COMU (153 mg) and TMP (61 L) were added, and the mixture was stirred at room temperature for 3 hours. Then, N-(tert-butoxycarbonyl)-1,2-diaminoethane (58 mg) was added, and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)] (16 mL), and the mixture was stirred at room temperature overnight to perform deprotection. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. In DMF (28 mL), the obtained copolymer (276 mg) was dissolved, DOTA-tris(t-Bu ester) (96 mg), COMU (89 mg), and TMP (70 L) were added, and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)](16 mL) and the mixture was stirred at room temperature overnight to perform carboxyl group deprotection, and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to obtain the chelating agent-bonded copolymer (amide bond 1) (242 mg).

##STR00028##

[0217] For the chelating agent-bonded copolymer (amide bond 1) before the carboxyl group deprotection, the number of the chelating agent introduced to one molecule of the copolymer was analyzed from a .sup.1H-NMR spectrum measured by using NMR, and a result thereof was 11 mol/mol.

[Measurement Apparatuses and Conditions]

(1) .SUP.1.H-NMR Measurement

[0218] Apparatus: JNM-ECX400 (400 MHz)/JEOL Ltd. [0219] Solvent: dimethyl sulfoxide-de containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0220] Sample concentration: 20 mg/mL [0221] Measurement temperature: 25 C. [0222] Number of integration times: 256 times [0223] Results: FIG. 7

TABLE-US-00011 TABLE 11 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 134 Example 69 11

Examples 135 to 141

[0224] For the copolymers obtained in Examples 71 to 78, copolymers having different numbers of the chelating agent introduced to one molecule of each copolymer as shown in the following table were synthesized by appropriately changing charged amounts of the linker and the chelating agent by the same method as Example 134.

TABLE-US-00012 TABLE 12 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 135 Example 71 8 136 Example 72 4 137 Example 73 8 138 Example 75 5 139 Example 76 5 140 Example 77 9 141 Example 78 10

Example 142

Synthesis of Chelating Agent-Bonded Copolymer (Amide Bond 2)

[0225] To a solution of the copolymer obtained in Example 98 (300 mg) in DMF (15 mL), were added COMU (65 mg) and TMP (26 L), and the mixture was stirred at room temperature for 3 hours. Thereto was added p-NH.sub.2-Bn-DOTA-tetra(t-Bu ester) (114 mg), and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)] (32 mL) and the mixture was stirred at room temperature overnight to perform carboxyl group deprotection, and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to obtain the chelating agent-bonded copolymer (amide bond 2) (281 mg).

##STR00029##

[0226] For the chelating agent-bonded copolymer (amide bond 2) before the carboxyl group deprotection, the number of the chelating agent introduced to one molecule of the copolymer was analyzed from a .sup.1H-NMR spectrum measured by using NMR, and a result thereof was 7 mol/mol.

[Measurement Apparatuses and Conditions]

(1) .SUP.1.H-NMR Measurement

[0227] Apparatus: JNM-ECX400 (400 MHz)/JEOL Ltd. [0228] Solvent: dimethyl sulfoxide-d.sub.6 containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0229] Sample concentration: 20 mg/mL [0230] Measurement temperature: 25 C. [0231] Number of integration times: 256 times [0232] Results: FIG. 8

TABLE-US-00013 TABLE 13 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 142 Example 98 7

Examples 143 to 149

[0233] For the copolymers obtained in Examples 69 to 97, copolymers having different numbers of the chelating agent introduced to one molecule of each copolymer as shown in the following table were synthesized by appropriately changing charged amounts of the linker and the chelating agent by the same method as Example 142.

TABLE-US-00014 TABLE 14 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 143 Example 69 18 144 Example 89 15 145 Example 90 14 146 Example 93 30 147 Example 95 9 148 Example 96 16 149 Example 97 20

Example 150

Synthesis of Chelating Agent-Bonded Copolymer (Ester Bond 1)

[0234] In dichloromethane (7 mL), the copolymer obtained in Example 98 (400 mg) was dissolved, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (WSC-HCl) (69 mg) and 4-(dimethylamino)pyridine (DMAP) (44 mg) were added, and the mixture was stirred at room temperature for 3 hours. Then, 2-(tert-butoxycarbonylamino)-1-ethanol (183 L) was added, and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in the solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)] (16 mL), and the mixture was stirred at room temperature overnight to perform deprotection. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. In DMF (7 mL), the obtained copolymer (350 mg) was dissolved, DOTA-tris(t-Bu ester) (118 mg), COMU (88 mg), and TMP (35 L) were added, and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)] (16 mL) and the mixture was stirred at room temperature overnight to perform carboxyl group deprotection, and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to obtain the chelating agent-bonded copolymer (ester bond 1) (238 mg).

##STR00030##

[0235] For the chelating agent-bonded copolymer (ester bond 1) before the carboxyl group deprotection, the number of the chelating agent introduced to one molecule of the copolymer was analyzed from a .sup.1H-NMR spectrum measured by using NMR, and a result thereof was 12 mol/mol.

[Measurement Apparatuses and Conditions]

(1) 1H-NMR Measurement

[0236] Apparatus: JNM-ECX400 (400 MHz)/JEOL Ltd. [0237] Solvent: dimethyl sulfoxide-d.sub.6 containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0238] Sample concentration: 20 mg/mL [0239] Measurement temperature: 25 C. [0240] Number of integration times: 256 times [0241] Results: FIG. 9

TABLE-US-00015 TABLE 15 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 150 Example 98 12

Example 151

Synthesis of Chelating Agent-Bonded Copolymer (Ester Bond 2)

[0242] To a solution of the copolymer obtained in Example 100 (400 mg) in dichloromethane (7 mL), were added WSC-HCl (69 mg) and DMAP (44 mg), and the mixture was stirred at room temperature for 3 hours. Thereto was added tert-butyl glycolate (111 L), and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)] (16 mL), and the mixture was stirred at room temperature overnight to perform carboxyl group deprotection. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. To a solution of the obtained copolymer (350 mg) in DMF (7 mL), were added p-NH.sub.2Bn-DOTA-tetra(t-Bu ester) (174 mg), COMU (88 mg), and TMP (35 L), and the mixture was stirred at 30 C. for 3 days. The reaction solution was dialyzed and purified (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, and external liquid: methanol), and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to recover the copolymer. The obtained copolymer was dissolved in a solution mixture of DCM and TFA [DCM/TFA=5/3 (v/v)] (16 mL) and the mixture was stirred at room temperature overnight to perform carboxyl group deprotection, and then the solvent was removed by the distillation under reduced pressure and the vacuum drying to obtain the chelating agent-bonded copolymer (ester bond 2) (54 mg).

##STR00031##

[0243] For the chelating agent-bonded copolymer (ester bond 2) before the carboxyl group deprotection, the number of the chelating agent introduced to one molecule of the copolymer was analyzed from a .sup.1H-NMR spectrum measured by using NMR, and a result thereof was 13 mol/mol.

[Measurement Apparatuses and Conditions]

(1) .SUP.1.H-NMR Measurement

[0244] Apparatus: JNM-ECX400 (400 MHz)/JEOL Ltd. [0245] Solvent: dimethyl sulfoxide-d.sub.6 containing 0.03% tetramethylsilane/KANTO CHEMICAL CO., INC. [0246] Sample concentration: 20 mg/mL [0247] Measurement temperature: 25 C. [0248] Number of integration times: 256 times [0249] Results: FIG. 10

TABLE-US-00016 TABLE 16 Number of chelating agent introduced Copolymer to one molecule of Example used copolymer (mol/mol) 151 Example 98 13

Example 152

Preparation of Gd-DOTA-Bonded SCNP

[0250] In purified water (50 mL), the chelating agent-bonded copolymer obtained in Example 106 (500 mg) was dissolved and the mixture was bubbled with argon for 20 minutes. After addition of gadolinium chloride hexahydrate (313 mg), the solution was adjusted to pH 6.5 with 1N aqueous sodium hydroxide solution. This solution was stirred at 60 C. for 3 hours to perform a complex formation reaction between Gd and DOTA. Then, dialysis purification was performed using purified water as an external liquid (dialysis membrane: Spectra/Por Regenerated Cellulose Membrane 6, molecular cut off: 3.5 kDa, external liquid: purified water) to roughly purify free Gd. The free Gd was precipitated as phosphate by adding 10-fold concentrated Dulbecco's phosphate buffered saline (D-PBS()) (8.5 mL) and stirring for 30 minutes. This solution was filtered through a filter (pore diameter: 0.2 m), and then dialyzed against purified water again to remove salts contained in the buffer. An obtained inner fluid of the dialysis membrane was lyophilized to obtain the Gd-DOTA-bonded SCNP (356 mg).

[0251] The number of Gd bonded to one molecule of the copolymer of the Gd-DOTA-bonded SCNP obtained after the purification was measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES), and was 9.4 mol/mol. Further, a Z-average particle diameter and a polydispersity index of the Gd-DOTA-bonded SCNP when dispersed in PBS were measured by dynamic light scattering (DLS), and a result of the Z-average particle diameter was 9.3 nm (polydispersity index: 0.15).

[Measurement Apparatuses and Conditions]

(1) ICP-AES Measurement

[0252] Apparatus: sequential high frequency plasma light emitting apparatus ICPE-9000/SHIMADZU CORPORATION [0253] Pretreatment apparatus: microwave sample pretreatment apparatus ETHOS EASY/Milestone General [0254] Measurement wavelength: 342 nm [0255] Standard solution: gadolinium standard solution (Gd1000) for ICP analysis/FUJIFILM Wako Pure Chemical Corporation [0256] Internal standard substance: yttrium standard solution (Y1000) for ICP analysis/FUJIFILM Wako Pure Chemical Corporation [0257] Sample concentration: 10 mg/mL (in terms of polymer)

(2) DLS Measurement

[0258] Apparatus: Zetasizer NanoZS/Malvern Instruments Ltd. [0259] Measurement temperature: 25 C. [0260] Sample concentration: 10 mg/mL [0261] Results: FIG. 11

TABLE-US-00017 TABLE 17 Number of Gd Z-average bonded to one particle Poly- Copolymer molecule of diameter dispersity Example used copolymer (mol/mol) (nm) index 152 Example 106 3.4 9.3 0.15

Examples 153 to 198

[0262] For the chelating agent-bonded copolymers obtained in Examples 107 to 151, contrast agent molecule-bonded SCNPs having different numbers of the paramagnetic metal bonded to one molecule of each copolymer as shown in the following table were synthesized by appropriately changing a type and a charged amount of the paramagnetic metal, and using a similar method as in Example 152.

TABLE-US-00018 TABLE 18 Number of paramagnetic Z-average Paramagnetic metal element bonded particle Poly- Copolymer metal to one molecule of diameter dispersity Example used element copolymer (mol/mol) (nm) index 153 Example 107 Gd 9.5 8.3 0.14 154 Example 108 Gd 0.8 8.1 0.28 155 Example 109 Gd 3.2 6.2 0.28 156 Example 110 Gd 2.9 6.5 0.26 157 Example 111 Gd 8.4 6.6 0.17 158 Example 112 Gd 7.7 6.4 0.12 159 Example 113 Gd 10.7 7.0 0.15 160 Example 114 Gd 11.2 7.1 0.17 161 Example 115 Gd 17.3 8.7 0.16 162 Example 116 Gd 15.9 8.6 0.18 163 Example 117 Gd 26.1 17.1 0.39 164 Example 118 Gd 18.1 19.0 0.41 165 Example 119 Gd 14.9 10.4 0.20 166 Example 120 Gd 16.5 11.1 0.30 167 Example 121 Gd 8.1 9.9 0.12 168 Example 122 Gd 6.3 10.2 0.15 169 Example 123 Gd 35.1 10.3 0.17 170 Example 124 Gd 19.6 10.9 0.21 171 Example 125 Gd 22.7 10.0 0.21 172 Example 126 Gd 17.6 10.9 0.27 173 Example 127 Gd 2.2 10.2 0.58 174 Example 128 Gd 4.1 4.9 0.14 175 Example 129 Gd 10.3 11.6 0.38 176 Example 130 Gd 27.0 10.1 0.20 177 Example 131 Gd 21.4 10.1 0.19 178 Example 132 Gd 12.6 12.5 0.40 179 Example 133 Gd 14.7 10.8 0.18 180 Example 134 Gd 11.4 9.4 0.25 181 Example 135 Gd 6.0 11.2 0.58 182 Example 136 Gd 3.9 9.8 0.46 183 Example 137 Gd 6.5 23.2 1.08 184 Example 138 Gd 4.9 5.2 0.21 185 Example 139 Gd 3.9 18.2 1.00 186 Example 140 Gd 10.4 5.6 0.19 187 Example 141 Gd 11.9 5.8 0.17 188 Example 142 Gd 4.8 9.5 0.21 189 Example 143 Gd 13.0 9.1 0.15 190 Example 144 Gd 10.0 7.9 0.08 191 Example 145 Gd 10.0 8.4 0.15 192 Example 146 Gd 24.0 9.2 0.19 193 Example 147 Gd 7.0 8.6 0.17 194 Example 148 Gd 13.3 18.1 0.25 195 Example 149 Gd 23.0 20.4 0.29 196 Example 150 Gd 9.2 9.5 0.19 197 Example 151 Gd 9.5 8.8 0.17 198 Example 143 Mn 9.4 7.4 0.15

Comparative Example 1

Preparation of Magnescope Solution

[0263] To PBS (4.6 mL), was added a Magnescope intravenous injection 38% syringes 10 mL (Guerbet Japan KK) (0.4 mL) to prepare a PBS solution in which Gd was 0.5 mol/L.

[Test Example 1] Measurement of Relaxivity

[0264] The Gd-DOTA-bonded SCNP obtained in Example 152 was adjusted such that the Gd ion concentration in PBS was 1, 0.5, 0.25, 0.125, 0.0625, or 0.03125 mmol/L, respectively, and a longitudinal relaxation time (T.sub.1 time) and a transverse relaxation time (T.sub.2 time) were measured. From the obtained T.sub.1 time and T.sub.2 time, longitudinal relaxivity (r.sub.1) and transverse relaxivity (r.sub.2) were given according to equations 1 and 2, respectively, and were 13.1 and 15.9. The T.sub.1 time and the T.sub.2 time of the magnescope solution (Comparative Example 1) were measured by the same procedure as described above. From the obtained T.sub.1 time and T.sub.2 time, r.sub.1 was 4.1, and r.sub.2 was 4.9.

[Measurement Apparatuses and Conditions]

[Measurement Apparatus]

[0265] Permanent magnet type 1 Tesla magnetic resonance imaging (MRI) apparatus (1.0 Tesla, ICON, Bruker Biospin, Ettlingen, Germany)

[Conditions]

Longitudinal Relaxivity Measurement (r.SUB.1.):

Inversion Recovery Spin-Echo Method

[0266]
(RARE Sequence, TR/TE=20,000/17 msec, RARE factor=4,Inversion Time=45,100,200,400,800,1,600,3,200,6,400,8,000,10,000,120,000 msec, FOV=3.843.84 cm, Matrix Size=6464, Number of slice=1,Slice thickness=3 mm, NEX=1,Scan time=5 min 20 sec per scan)

[Conditions]

Transverse Relaxivity Measurement (r.SUB.2.)

Multi-Echo Spin-Echo Method

[0267]
(Reference measurement: MSME Sequence, TR=15,000 msec, TE=40, 80, 120, 160, 200 to 3,072 msec or 10,240 msec (256 step), FOV=3.843.84 cm, Matrix Size=6464, Number of slice=1, Slice thickness=3 mm, NEX=1, Scan time=16 min 00 sec)

Formula 1 Definition of Relaxivity r.SUB.1

[00001]$1/T_1=1/T_1^0+r_1\left[\mathrm{Gd}\right]$

[0268] In the equation, T.sub.1 represents a longitudinal relaxation time(s) of water in the presence of the contrast agent, T.sub.1.sup.0 represents a longitudinal relaxation time(s) of water (in the absence of the contrast agent), r.sub.1 represents the longitudinal relaxivity (mS-is-1), and [Gd] represents a concentration (mmol/L) of Gd ions contained in the contrast agent.

Equation 2 Definition of Relaxivity r.SUB.2

[00002]$1/T_2=1/T_2^0+r_2\left[\mathrm{Gd}\right]$

[0269] In the equation, T.sub.2 represents a longitudinal relaxation time(s) of water in the presence of the contrast agent, T.sub.2.sup.0 represents a longitudinal relaxation time (s) of water (in the absence of the contrast agent), r.sub.2 represents the transverse relaxivity (mS.sup.2s.sup.1), and [Gd] represents the concentration (mmol/L) of Gd ions contained in the contrast agent.

[Test Example 2] Contrast Test

[0270] Tumor-bearing models obtained by subcutaneously transplanting a mouse colon cancer cell line C26 into female nude mice (BALB/c-nu/nu, 4 weeks old; Japan SLC, Inc.) were used for the contrast test.

[0271] The mouse colon cancer cell line C26 subcultured in a CO.sub.2 incubator was suspended in a liquid medium (Dulbecco's Modified Eagle's Medium-high glucose, Sigma-Aldrich), and injected subcutaneously in the back of each nude mice such that the number of cells per mouse was 110.sup.6/50 L. Then, the nude mice were raised for about 10 days, and then administered with the agent when an average value of tumor volumes of the mice was grown to about 200 mm. The Gd-DOTA-bonded SCNP obtained in Example 152 was intravenously administered through the tail vein, and the contrast test was performed immediately after the administration, 1 hour after the administration, 2 hours after the administration, and 24 hours after the administration. As a comparison, the magnescope solution (Comparative Example 1) was used, and administered in a similar manner. A dose of each agent was 0.4 mmol/kg in terms of Gd.

[0272] A temporal change in the imaging ability is shown in FIG. 12. In a case of the Gd-DOTA-bonded SCNP, an effect of enhancing the contrast was confirmed immediately after the administration, and the effect was sustained until 24 hours after the administration with a peak at 2 hours after the administration. Meanwhile, in a case of the magnescope solution (Comparative Example 1), an effect of enhancing the contrast was confirmed immediately after the administration, and the effect was reduced to the same extent as before the administration after 1 hour from the administration. Further, the effect of enhancing the contrast immediately after the administration of the magnescope solution was weaker than the effect of enhancing the contrast after 2 hours from the administration of the Gd-DOTA-bonded SCNP. The above results indicate that the Gd-DOTA-bonded SCNP has an excellent imaging effect compared to the magnescope solution.

[Measurement Apparatuses and Conditions]

[Measurement Apparatus]

[0273] Permanent magnet type 1 Tesla magnetic resonance imaging (MRI) apparatus (1.0 Tesla, ICON, Bruker Biospin, Ettlingen, Germany)

[Conditions]

T1-Weighted Image:

[0274]
Spin echo method (MSME Sequence, TR/TE=400/10 msec, FOV=3.843.84 cm, Matrix Size=256256, Number of slice=1, Slice thickness=3 mm, NEX=10, Scan time=17 min 4 sec)