JP6085983B2 - Blocking agent, carrier on which antigen or antibody to target substance is immobilized, in vitro diagnostic reagent and kit containing the same, and method for detecting target substance - Google Patents

Description

  The present invention relates to a blocking agent, a carrier on which an antigen or antibody against a target substance is immobilized, an in vitro diagnostic reagent and kit including the same, and a method for detecting the target substance.

  An immunolatex agglutination measurement method using an agglutination reaction that occurs between an antigen (antibody) that is a target substance and an antibody (antigen) against the antigen (antibody) is a method for detecting a target substance in a specimen by in vitro diagnosis. Although it is widely used in chemical research and other fields, antigens that are target substances and foreign substances in serum are directly adsorbed on the particle surface, which causes unintended latex particle aggregation to be detected and accurate measurement. There is a problem of hindering.

Therefore, for the purpose of reducing such noise, usually, a biological substance such as albumin, casein, gelatin or the like is previously coated on the particles as a blocking agent.
However, noise may occur even when such blocking treatment is performed, and when these biologically derived blocking agents are used, there is also a problem of biological contamination represented by BSE.

  Therefore, blocking agents by chemical synthesis such as polymers having polyoxyethylene (Patent Documents 1 and 2) and polyoxyethylene / pentaethylenehexamine block copolymers (Patent Documents 3 and 4) have been developed. The blocking agents described in 1 and 2 have insufficient noise reduction effects, and the blocking agents described in Patent Documents 3 and 4 require complicated purification prior to production.

JP 11-287802 A Japanese Patent No. 34079797 JP 2006-226882 A International Publication No. 2005/010529

  The problem to be solved by the present invention is that a blocking agent excellent in the effect of reducing noise when detecting a target substance in a sample by in vitro diagnosis, an antigen or an antibody against the target substance is immobilized, and the blocking agent is further coated It is an object of the present invention to provide a carrier, an in vitro diagnostic reagent and kit including the same, and a method for detecting a target substance.

  Therefore, the present inventors have found that a polymer having a repeating unit having a sulfinyl group in the side chain is excellent in the effect of reducing noise when detecting a target substance in a sample by in vitro diagnosis. completed.

  That is, this invention provides the blocking agent containing the polymer which has a repeating unit which has a sulfinyl group in a side chain.

  In addition, the present invention provides a carrier (hereinafter simply referred to as an antigen or an antibody against a target substance) partially or entirely coated with a polymer having a repeating unit having a sulfinyl group in the side chain. (Also referred to as “immobilized carrier”).

  Furthermore, the present invention provides a reagent for use in detecting a target substance in a specimen by in vitro diagnosis, which contains the above-described immobilized carrier.

  Furthermore, the present invention provides a kit for use in detection of a target substance in a specimen by in vitro diagnosis, comprising at least the above-described reagent.

  Furthermore, the present invention provides a method for detecting a target substance in a sample by in vitro diagnosis, the method comprising mixing the immobilized carrier and a sample that may contain the target substance. It is to provide.

The blocking agent of the present invention is excellent in the effect of reducing noise when detecting a target substance in a sample by in vitro diagnosis.
Moreover, according to the carrier, reagent, kit, and detection method of the present invention, a target substance in a sample can be detected accurately and simply by in vitro diagnosis.

[Blocking agent]
The blocking agent of this invention contains the polymer which has a repeating unit (henceforth a repeating unit (A)) which has a sulfinyl group in a side chain.

<Repeating unit (A)>
As said repeating unit (A), what shows hydrophilic property is preferable. Here, in this specification, hydrophilic means that it has a property with strong affinity with water. Specifically, a homopolymer consisting of only one type of repeating unit (having a number average molecular weight of about 10,000 to 100,000 by the measurement method of the Examples) is 1 g or more per 100 g of pure water at room temperature (25 ° C.). When dissolved, the repeating unit is hydrophilic.
Moreover, as said repeating unit (A), the thing of Hydrophile-Lipophile Balance (HLB value) which shows the scale of hydrophilicity hydrophobicity is 10 or more is preferable. In the case of obtaining high hydrophilicity, the HLB value is more preferably 15 or more, further preferably 20 to 40, and particularly preferably 20 to 30.
Further, in this specification, the HLB value means a value calculated from the ratio of the organic value and the inorganic value of the compound (Oda equation), and “Formation Design with Organic Concept Diagram” [1998, NIHON]. EMULSION CO. , LTD]. For example, the HLB value of the repeating unit (A) contained in the copolymer of N-1-1 described in Examples described later is (60 × 1 + 140 × 1 + 100 × 3) / (20 × 10 + 40 × 1 + (− 10 ) × 3) × 10 = 23.8.

The repeating unit (A) is not particularly limited, but nonionic ones are preferred.
In addition to the sulfinyl group, the repeating unit (A) may have a hydrophilic group such as a hydroxy group, a carboxy group, an amino group, a sulfo group, a thiol group, a phosphoric acid group, or an aldehyde group. Further, the position and the number of such hydrophilic groups are arbitrary, but the position is preferably a side chain of the polymer. On the other hand, the number of hydrophilic groups other than sulfinyl groups is preferably 0 to 12, more preferably 0 to 10, more preferably 0 to 5 in one repeating unit from the viewpoint of obtaining appropriate hydrophilicity. More preferably, 0 to 3 is more preferable, 1 to 3 is more preferable, and 2 or 3 is particularly preferable. Among the hydrophilic groups, a hydroxy group is preferable from the viewpoint of obtaining appropriate hydrophilicity. In addition, as long as the effect of this invention is not lost, some sulfinyl groups contained in a polymer may be sulfide groups or sulfonyl groups.

  Specific examples of the repeating unit (A) include a repeating unit containing at least one structure represented by the following formula (1) in the side chain. As the polymer species to be a repeating unit having the structure represented by the formula (1) in the side chain, known polymers can be used, among which (meth) acrylate polymer species and (meth) acrylamide polymer species Styrene-based polymer species are preferred. More specifically, a repeating unit represented by the following formula (2) is exemplified.

[In Formula (1), R < ³ > shows a direct bond or a C1-C24 bivalent organic group, and R < ⁴ > shows a C1-C10 organic group. ]

[In formula (2), R ¹ represents a hydrogen atom or a methyl group, R ² is a group -O-, a group * - (C = O) -O- , group * - (C = O) -NR ⁵ -, group * -NR ⁵ - (C = O) - (R ⁵ is a hydrogen atom or an organic group having 1 to 10 carbon atoms, and *, R ¹ in the formula (2) is attached R represents a position bonded to a carbon atom) or a phenylene group, and R ³ and R ⁴ are as defined above. ]
Here, each symbol in the formulas (1) and (2) will be described in detail.

R ¹ represents a hydrogen atom or a methyl group, preferably a methyl group.

R ² represents a group —O—, a group * — (C═O) —O—, a group * — (C═O) —NR ⁵ —, a group * —NR ⁵ — (C═O) — or phenylene. Indicates a group. Examples of such a phenylene group include a 1,2-phenylene group, a 1,3-phenylene group, and a 1,4-phenylene group.

The number of carbon atoms of the organic group represented by the R ⁵ is preferably 1 to 10, more preferably from 2 to 8, more preferably from 2 to 6. Examples of the organic group include hydrocarbon groups. Such a hydrocarbon group is a concept including an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

The aliphatic hydrocarbon group in R ⁵ may be linear or branched, and specifically includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a sec-butyl group. Alkyl groups such as tert-butyl group, pentyl group, hexyl group, heptyl group and octyl group.
The alicyclic hydrocarbon group is roughly classified into a monocyclic alicyclic hydrocarbon group and a bridged ring hydrocarbon group. Examples of the monocyclic alicyclic hydrocarbon group include cycloalkyl groups such as a cyclopropyl group and a cyclohexyl group. Examples of the bridged ring hydrocarbon group include an isobornyl group.
Examples of the aromatic hydrocarbon group include aryl groups such as a phenyl group.

Among R ² as described above, from the viewpoint of the blocking effect, the group * — (C═O) —O— and the phenylene group are preferable, and the group * — (C═O) —O— is particularly preferable.

R ³ represents a direct bond or a divalent organic group having 1 to 24 carbon atoms. Such direct bonds include single bonds.

Among such R ^3, a divalent organic group having 1 to 24 carbon atoms is preferable. The carbon number of such a divalent organic group is preferably 2 to 18, more preferably 2 to 10, still more preferably 2 to 9, and particularly preferably 3 to 6.

  Examples of the divalent organic group include a divalent hydrocarbon group. The divalent hydrocarbon group is preferably a divalent aliphatic hydrocarbon group and may be linear or branched. Specifically, methane-1,1-diyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, Propane-1,3-diyl group, propane-2,2-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane-1,4 -Diyl group, pentane-1,5-diyl group, hexane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, etc. An alkanediyl group may be mentioned.

The divalent hydrocarbon group may have a substituent and may contain an ether bond between carbon-carbon bonds.
Examples of the substituent that the divalent hydrocarbon group may have include the hydrophilic group. The number of the substituents is preferably 1 to 5, more preferably 1 to 3, and further preferably 1 or 2.
Moreover, as the number of the ether bonds which the said bivalent hydrocarbon group may contain, 0-5 are preferable and 0-3 are more preferable.

  Specific examples of the divalent organic group include a linking group represented by the following formula (3) and an alkanediyl group having 1 to 24 carbon atoms, and more preferably represented by the formula (3). A linking group.

[In Formula (3), R ⁶ is a single bond, a group —R ⁸ —O— (R ⁸ represents an alkanediyl group having 1 to 4 carbon atoms) or a linking group represented by the following Formula (4). R ⁷ represents an alkanediyl group having 1 to 4 carbon atoms, n represents 1 or 2, and ** represents a position bonded to a sulfur atom in the formulas (1) and (2). ]

[In the formula (4), R ⁹ represents an alkanediyl group having 1 to 4 carbon atoms, R ¹⁰ represents an alkanediyl group having 2 or 3 carbon atoms, m ¹ represents 1 or 2, m ² Represents an integer of 1 to 3. ]

R ⁶ is preferably a single bond or a group —R ⁸ —O—, and particularly preferably a single bond.

The alkanediyl group represented by R ⁷ , R ⁸ and R ⁹ has 1 to 4 carbon atoms, but 1 or 2 is preferable.
The alkanediyl group may be linear or branched, and examples thereof include the same alkanediyl groups as described above.

The carbon number of the alkanediyl group represented by R ¹⁰ is preferably 2. Examples of the alkanediyl group include the same as those represented by R ⁷ . When m ² is 2 or 3, m ² R ¹⁰ may be the same or different.
Further, 1 is preferable as n and m ^1, 1 or 2 is preferable as m ^2.

R ⁴ represents an organic group having 1 to 10 carbon atoms. Examples of such an organic group include the same groups as those represented by R ⁵ . In addition, when R ⁴ is a hydrocarbon group, such a hydrocarbon group may have a substituent, and the substituent and the number thereof may be the divalent hydrocarbon group. The thing similar to a good thing is mentioned. From the viewpoint of hydrophilicity, R ⁴ preferably does not contain a ring structure such as a cycloalkyl group, an aryl group, or an aralkyl group.

Preferable specific examples of R ⁴ as described above include organic groups having 1 to 10 carbon atoms having the hydrophilic group, more preferably a monovalent group represented by the following formula (5), carbon. It is a C1-C10 alkyl group, More preferably, it is a monovalent group represented by Formula (5).

Wherein (5), k ¹ represents an integer of 1 to 4, k ² is an integer of 0 to 4, *** the formula (1), combined with the sulfur atom in (2) Indicates the position to perform. ]

In formula (5), k ¹ is preferably 1 or 2. As the k ^2, preferably an integer of 0 to 2, 0 or 1 are more preferable.

Further, the lower limit of the total content of the repeating unit (A) is preferably 10 mol% or more, more preferably 20 mol% or more, more preferably 30 mol% in all repeating units from the viewpoint of imparting water solubility and blocking effect. The above is more preferable, and 40 mol% or more is more preferable.
On the other hand, the upper limit is preferably 99 mol% or less, more preferably 90 mol% or less, still more preferably 85 mol% or less, still more preferably 80 mol% or less, from the viewpoint of adsorption with the carrier. 70 mol% or less is still more preferable.
The content of the repeating unit (A) can be measured by ¹³ C-NMR or the like.

<Repeating unit (B)>
The polymer used in the present invention preferably further has a hydrophobic repeating unit (hereinafter also referred to as a repeating unit (B)). Here, “hydrophobic” means having a property of low affinity with water. Specifically, a homopolymer consisting of only one type of repeating unit (having a number average molecular weight of about 10,000 to 100,000 according to the measurement method in Examples) is dissolved in 100 g of pure water at room temperature (25 ° C.). If the amount is less than 1 g, the repeating unit is hydrophobic.
In addition, the HLB value of the repeating unit (B) is preferably less than 20, more preferably less than 15, more preferably less than 10 and less than 10, more preferably 0.1 to 5 in order to obtain high hydrophobicity. Particularly preferred.

  The repeating unit (B) includes known ones exhibiting hydrophobicity, and is not particularly limited, but is selected from styrenes, (meth) acrylates and (meth) acrylamides from the viewpoint of adsorption with a carrier. Those derived from more than one species of monomers are preferred, and those derived from styrenes are more preferred.

  As the repeating unit derived from the styrenes, a repeating unit represented by the following formula (6) is preferable.

[In Formula (6), R < ¹¹ > shows a hydrogen atom or a methyl group, R < ¹² > shows a C1-C10 organic group, and p shows the integer of 0-5. ]

In formula (6), examples of the organic group represented by R ¹² include the same groups as those represented by R ⁵ , but the carbon number thereof is preferably 1 to 6, and more preferably 1 to 3. It is. Moreover, the thing without a hydrophilic group is preferable. Such an organic group may be substituted with an alkoxy group having 1 to 3 carbon atoms. Also, when p is integer of 2 to 5, p number of R ¹² may be the same or different.

  Moreover, although p shows the integer of 0-5, 0-3 are preferable and 0 is more preferable.

  Specific examples of the repeating unit derived from styrenes include styrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-tert- Examples thereof include repeating units derived from butylstyrene, α-methylstyrene and the like.

Examples of the (meth) acrylates include (meth) acrylic acid C such as methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. _1-10 alkyl; (meth) acrylic acid C _6-10 cycloalkyl such as methacrylic cyclohexyl; (meth) acrylic such as 1-methoxyethyl (meth) acrylate and 2-methoxyethyl (meth) acrylate Acid C _1-10 alkoxy C _1-10 alkyl; (meth) acrylate 1-adamantyl, (meth) acrylate 1-methyl- (1-adamantylethyl), (meth) acrylate tricyclo [5.2.1. And (meth) acrylic acid ester having a bridged cyclic hydrocarbon group having 8 to 16 carbon atoms such as 0 ^2,6 ] decan-8-yl. In these (meth) acrylates, the C _1-10 alkyl group is preferably a C _1-8 alkyl group, and the C _6-10 cycloalkyl group is preferably a C _6-8 cycloalkyl group. _{The 1-10} alkoxy group is preferably a C _1-6 alkoxy group, and the bridged ring hydrocarbon group having 8 to 16 carbon atoms is preferably a bridged ring hydrocarbon group having 8 to 12 carbon atoms.

Examples of the (meth) acrylamides include N, N-diC _1-10 alkyl (meth) acrylamide; N-C _1-10 alkyl (meth) acrylamide such as N-isopropyl (meth) acrylamide; N In addition to N—C _2-10 alkanoyl C _1-10 alkyl (meth) acrylamide such as — (1,1-dimethyl-2-acetylethyl) (meth) acrylamide, (meth) acryloylpiperidine and the like can be mentioned. In these (meth) acrylamides, the C _1-10 alkyl group is preferably a C _3-10 alkyl group, and the C _2-10 alkanoyl group is preferably a C _2-6 alkanoyl group.

The lower limit of the total content of repeating units (B) is preferably 1 mol% or more, more preferably 10 mol% or more, and more preferably 15 mol% or more in all repeating units from the viewpoint of adsorption with the carrier. Preferably, 20 mol% or more is more preferable, and 30 mol% or more is more preferable.
On the other hand, the upper limit is preferably 90 mol% or less, more preferably 80 mol% or less, still more preferably 70 mol% or less, and even more preferably 60 mol% or less in all repeating units from the viewpoint of imparting water solubility.
In addition, what is necessary is just to measure content of a repeating unit (B) similarly to content of a repeating unit (A).

  Further, the molar ratio [(A) :( B)] of the repeating unit (A) and the repeating unit (B) contained in the polymer is preferably 10: 1 to 10:30 from the viewpoint of the blocking effect, 10: 2 to 10:20 are more preferable, and 10: 3 to 10:15 are still more preferable.

  The polymer used in the present invention may have a hydrophilic repeating unit (C) other than the repeating units (A) and (B). Such hydrophilic repeating unit (C) includes an anionic monomer (anionic monomer), a cationic monomer (cationic monomer), or a nonionic monomer (nonionic monomer). The thing which originates is mentioned, These 1 type or 2 types or more may be included.

  Examples of the anionic monomer include unsaturated carboxylic acid monomers such as vinyl benzoic acid and (meth) acrylic acid; unsaturated sulfonic acid monomers such as styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and isoprene sulfonic acid. Can be mentioned.

  Examples of the cationic monomer include those having an unsaturated bond with a primary to quaternary amino group such as allylamine, aminostyrene, N, N-dimethylaminopropyl (meth) acrylamide methyl chloride quaternary salt and the like.

  In addition, examples of nonionic monomers include unsaturated carboxylic acid ester monomers having a hydroxy group such as hydroxyethyl (meth) acrylate, glyceryl (meth) acrylate, and polyoxyethylene (meth) acrylate; N- (2-hydroxy And (meth) acrylamide monomers having a hydroxy group such as ethyl) (meth) acrylamide.

  The total content of the repeating unit (C) is preferably 0 to 49 mol%, more preferably 0 to 20 mol%, still more preferably 0 to 10 mol%, and 0 to 1 mol% in all repeating units. Particularly preferred.

  In addition, when the polymer used in the present invention is a copolymer, the arrangement of the repeating units is not particularly limited, and the copolymer may be a block copolymer, a graft copolymer, a random copolymer, an alternating copolymer, or the like. Any of copolymers may be used.

Moreover, as a number average molecular weight ( _Mn ) of the polymer used by this invention, 5000-1 million are preferable, 7000-200000 are more preferable, and 10,000-150,000 are especially preferable. When the number average molecular weight is 5000 or more, the blocking effect is improved. On the other hand, when the number average molecular weight is 1 million or less, the viscosity is suppressed and the handling becomes easy.
Moreover, as a weight average molecular weight ( _Mw ) of the polymer used by this invention, 5000-5 million are preferable, 7000-1 million are more preferable, 7000-200,000 are still more preferable.
Moreover, as molecular weight distribution ( _Mw / _Mn ), 1.0-5.0 are preferable, 1.0-4.0 are more preferable, 1.0-3.0 are still more preferable, 1.5- 2.5 is particularly preferred.
In addition, what is necessary is just to measure the said number average molecular weight and a weight average molecular weight according to the method as described in the Example mentioned later.

Moreover, as a polymer used by this invention, a water-soluble thing is preferable from a viewpoint of a blocking effect. Here, in the present specification, water-soluble means that the polymer becomes transparent when added to and mixed with water (25 ° C.) so that the polymer solid content is 1% by mass.
Moreover, as a polymer used by this invention, a nonionic thing is preferable.

  Moreover, as a polymer used by this invention, the thing whose HLB value is the range of 10-22 is preferable from a viewpoint of provision of water solubility and a blocking effect.

Next, the manufacturing method of the polymer used by this invention is demonstrated.
The polymer used in the present invention is (1) introducing a sulfide group into the side chain of a known polymer and converting the sulfide group to a sulfinyl group, and (2) forming a side chain when polymerized. A monomer having a sulfide group in a portion thereof is polymerized or copolymerized with another monomer, and the sulfide group of the obtained (co) polymer is converted into a sulfinyl group, (3) or when the side chain is polymerized A monomer having a sulfinyl group in the portion can be produced by polymerization or copolymerization with other monomers.
The said manufacturing method is concretely demonstrated taking the example of the manufacturing method of the following copolymer (N-1).
That is, a copolymer (S-1) is obtained by the step 1-A-1 and the step 1-A-2, or by the step 1-B or the step 1-C, and the copolymer (G- A copolymer (N-1) is obtained through 1).

  (Each symbol in the formula is as defined above.)

<Step 1-A-1>
Step 1-A-1 is a step of obtaining a copolymer (M-1) by polymerizing the compound (A-1-1) and the compound (B-1) in the presence of a polymerization initiator.
Examples of the compound (A-1-1) include (meth) acrylic acid and the like, and these can be used alone or in combination of two or more.
Moreover, the said styrene is mentioned as a compound (B-1), As the total usage-amount, 0.001-1.5 molar equivalent is preferable with respect to a compound (A-1-1).

Examples of the polymerization initiator include 2,2′-azobis (isobutyronitrile), dimethyl 2,2′-azobis (2-methylpropionate), 2,2′-azobis (4-methoxy). Azo initiators such as -2,4-dimethylvaleronitrile; peroxides such as di (3,5,5-trimethylhexanoyl) peroxide and benzoyl peroxide. These polymerization initiators include one kind. It can be used alone or in combination of two or more.
The total amount of the polymerization initiator used is usually about 0.0002 to 0.2 times by mass with respect to the compound (A-1-1).

Moreover, you may use a solvent and a chain transfer agent for process 1-A-1. Solvents include amide solvents such as dimethylformamide, dimethylacetamide and N-methylpyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; ester solvents such as ethyl acetate, butyl acetate and γ-butyrolactone; aromatics such as toluene and benzene Type | system | group solvent; Ether type | system | group solvents, such as 1, 4- dioxane, diethyl ether, are mentioned, These solvents can be used individually by 1 type or in combination of 2 or more types. The total amount of these solvents used is usually about 0.5 to 15 times by mass relative to the compound (A-1-1).
Examples of the chain transfer agent include mercaptoethanol, thioglycerol, tert-dodecyl mercaptan, and the like.

  The reaction time in step 1-A-1 is not particularly limited, but is usually about 0.5 to 24 hours, and the reaction temperature may be appropriately selected below the boiling point of the solvent, but is usually about 0 to 120 ° C. It is.

<Step 1-A-2>
Step 1-A-2, the copolymer obtained in Step 1-A-1 a -R ² of (M-1), is ring-opening addition to a glycidyl group or an oxetanyl group of the compound (C-1), In this step, a copolymer (S-1) is obtained.
Examples of the compound (C-1) used in Step 1-A-2 include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and the total use amount thereof is in the copolymer (M-1). 1.5-10 molar equivalent is preferable with respect to the repeating unit derived from a compound (A-1-1).

Step 1-A-2 is preferably performed in the presence of a catalyst. Examples of the catalyst include quaternary ammonium salts such as tetrabutylammonium bromide; quaternary phosphonium salts such as tetrabutylphosphonium bromide and tetrabutylphosphonium chloride. These catalysts are used singly or in combination of two or more. it can.
The total amount of the catalyst used is usually about 0.01 to 0.2 molar equivalents with respect to the repeating unit derived from the compound (A-1-1) in the copolymer (M-1).
Moreover, as a solvent used suitably at process 1-A-2, the thing similar to process 1-A-1 is mentioned.

  The reaction time in step 1-A-2 is not particularly limited, but is usually about 1 to 24 hours, and the reaction temperature may be appropriately selected below the boiling point of the solvent, but is usually about 40 to 200 ° C. .

<Step 1-B and Step 1-C>
In step 1-B and step 1-C, compound (A-1-2) or compound (A-1-3) and compound (B-1) are polymerized in the presence of a polymerization initiator, This is a step of obtaining a coalescence (S-1).
Examples of the compound (A-1-2) include glycidyl (meth) acrylate and oxetanyl (meth) acrylate, and examples of the compound (A-1-3) include vinylbenzyl glycidyl ether, 4-hydroxybutyl (meta ) Acrylate glycidyl ether and the like. In addition, these can be used individually by 1 type or in combination of 2 or more types.
Step 1-B and step 1-C may be performed in the same manner as in step 1-A-1.

<Process 2>
Step 2 includes ring-opening addition of —SR ⁴ to the glycidyl group or oxetanyl group of the copolymer (S-1) obtained in Step 1-A-2, Step 1-B or Step 1-C. In this step, a polymer (G-1) is obtained.
Examples of the compound represented by R ⁴ SH used in Step 2 include thioglycerol and mercaptoethanol, and thioglycerol is preferable from the viewpoint of improving hydrophilicity.
The total amount of the compound used is usually 0.1 to 20 molar equivalents relative to the repeating unit derived from the compound (A-1-1), (A-1-2) or (A-1-3). , Preferably 1 to 10 molar equivalents.

Step 2 is preferably performed in the presence of a catalyst. Examples of the catalyst include basic catalysts such as triethylamine and N, N-dimethyl-4-aminopyridine, and these catalysts can be used alone or in combination of two or more.
The total amount of the catalyst used is usually 0.01 to 40 molar equivalents with respect to the repeating unit derived from the compound (A-1-1), (A-1-2) or (A-1-3). .

  Step 2 is preferably performed in the presence of a solvent. As the solvent, in addition to the solvent that can be used in Step 1, an alcohol solvent such as ethanol and methanol, or a mixed solvent thereof can be used, and the total amount used is usually 0 with respect to the copolymer (S-1). About 5 to 20 times the mass.

  The reaction time in step 2 is not particularly limited, but is usually about 1 to 8 hours, and the reaction temperature may be appropriately selected below the boiling point of the solvent, but is usually about 40 to 100 ° C.

  Step 2 may be performed before step 1-B or step 1-C, and then polymerization of step 1-B or step 1-C may be performed.

<Step 3>
Step 3 is a step of obtaining a copolymer (N-1) by converting the sulfide group of the copolymer (G-1) obtained in Step 2 into a sulfinyl group using an oxidizing agent. In addition, as long as the effect of this invention is not lost, some sulfinyl groups contained in a copolymer may become a sulfide group or a sulfonyl group.

The oxidizing agent is roughly classified into an organic oxidizing agent and an inorganic oxidizing agent, and examples of the organic oxidizing agent include peracetic acid, perbenzoic acid, and metachloroperbenzoic acid. On the other hand, examples of the inorganic oxidizing agent include hydrogen peroxide, chromic acid, permanganate and the like. In addition, these oxidizing agents can be used individually by 1 type or in combination of 2 or more types.
Moreover, the usage-amount of an oxidizing agent is 1.0-10.0 mol normally with respect to the repeating unit derived from a compound (A-1-1), (A-1-2) or (A-1-3). It is about equivalent.

Step 3 is preferably performed in the presence of a solvent. Examples of such a solvent include water; amide solvents such as dimethylformamide and dimethylacetamide; alcohol solvents such as methanol and ethanol, and the like. These solvents can be used alone or in combination of two or more. Water and alcohol solvents are preferred.
The total amount of the solvent used is usually about 1 to 20 times by mass with respect to the copolymer (G-1).

  The reaction time in step 3 is not particularly limited, but is usually about 1 to 24 hours, and the reaction temperature may be appropriately selected below the boiling point of the solvent, but is usually about 25 to 70 ° C.

  In each step, isolation of each reaction product may be performed by filtration, washing, drying, recrystallization, reprecipitation, dialysis, centrifugation, extraction with various solvents, neutralization, chromatography, etc., if necessary. Ordinary means may be combined as appropriate.

Then, as shown in Examples below, a polymer having a repeating unit having a sulfinyl group in the side chain obtained as described above is coated with a carrier on which an antigen or antibody against a target substance in a sample is immobilized. As a result, noise due to non-specific adsorption to the carrier is significantly reduced. In addition, noise caused by the sensitizer can be reduced.
Therefore, the said polymer is useful as a blocking agent and can be used for the blocking method.
And such a polymer may be used as it is as a blocking agent, and can also be used as a raw material for manufacturing a blocking agent. In addition, the blocking agent of the present invention is easy to handle because it has good solubility in a solvent, and is not easily deteriorated over time, and has excellent storage stability.

Here, in this specification, blocking refers to preventing non-specific adsorption caused by other than antigen-antibody reaction between a target substance in a specimen and an antigen or antibody against the target substance in in vitro diagnosis, and This refers to preventing the occurrence of carrier aggregation due to non-specific adsorption. In addition, when the target substance in the specimen is adsorbed to the carrier without passing through the antigen or antibody against the target substance, an abnormality in the measured value may occur, and this includes preventing it.
Examples of the in vitro diagnosis include latex agglutination method, ELISA method, chemiluminescence method, immunoturbidimetric method (TIA) method, radioimmunoassay (RIA), immunochromatography and the like. This is particularly useful for preventing aggregation of the carrier due to the non-specific adsorption in the latex aggregation method.
Latex aggregation means that latex particles to which an antibody (or antigen) is bound and an antigen (or antibody) that is a target substance in a specimen bind to form an aggregate of two or more particles.
Examples of specimens generally include various biological liquid samples such as serum, plasma, urine, saliva, and crushed specimens of feces and foods. As a measurement sample, a sample diluent obtained by diluting a sample with a pH buffer solution, protein, amino acid, or the like may be used. In addition, target substances contained in such specimens are usually antigens such as receptors, enzymes, blood proteins, infectious disease-related antigens, microorganisms, viruses, hormones, environmental substances (eg, environmental hormones), and the like, and these antigens. It is sufficient that the antibody has a binding property to a specific antigen, and includes an antibody fragment.

  Moreover, as content of the said polymer in the blocking agent of this invention, 0.01-50 mass% is preferable and 0.01-10 mass% is more preferable. Even at such a low concentration, an excellent blocking effect is exhibited.

The blocking agent of the present invention may contain a solvent and a blocking agent other than the polymer of the present invention in addition to the above polymer, and one of these may be used alone or two or more of them may be combined.
Examples of the solvent include lower alcohols such as water, ethanol, methanol, and isopropanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; acetate esters such as ethyl acetate and butyl acetate; amides such as dimethylformamide; sulfoxides such as dimethyl sulfoxide; Is mentioned. Further, the blocking agent may be a living water-derived polymer such as bovine serum albumin (BSA) or a water-soluble polymer obtained by chemical synthesis.

[Immobilized carrier]
The carrier on which the antigen or antibody against the target substance of the present invention is immobilized is characterized in that it is partially or entirely coated with a polymer having a repeating unit having a sulfinyl group in the side chain.
The carrier is not particularly limited, and examples thereof include latex particles, gold nanoparticles, ELISA plates, immunochromatography membranes, and the like. Among these, latex particles are preferable. The immobilized carrier of the present invention is particularly useful for detection of a target substance in a specimen by a latex agglutination method.
Examples of latex particles include (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, (meth) acryloylmorpholine, N, N-dimethylamino. (Meth) acrylamide compounds such as propyl acrylamide, methyl chloride quaternary salt of N, N-dimethylaminopropyl acrylamide, diacetone acrylamide, N-vinylacetamide; methoxyethyl (meth) acrylate, methyl (meth) acrylate, ( (Meth) ethyl acrylate, (meth) propyl acrylate, (meth) lauryl acrylate, (meth) cyclohexyl cyclohexyl, (meth) acrylate isobornyl, benzyl (meth) acrylate, glycerol (meth) (Meth) acrylate compounds such as acrylate, polyethylene glycol (meth) acrylate, 2-hydroxyethyl (meth) acrylate; unsaturated aldehyde compounds such as acrolein; (meth) acrylic acid, itaconic acid, maleic anhydride, crotonic acid, etc. Unsaturated carboxylic acid compound or unsaturated carboxylic acid anhydride compound; unsaturated sulfonic acid compound such as styrene sulfonic acid, isoprene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid; styrene compound such as styrene and aminostyrene, Examples thereof include polymer particles derived from monomers such as allylamine and N-vinyl-2-pyrrolidone. Among such polymer particles, those which are a copolymer of a styrene compound and an unsaturated carboxylic acid compound are preferred, and a copolymer of styrene and an unsaturated carboxylic acid compound selected from acrylic acid, methacrylic acid and itaconic acid. What is a coalescence is more preferable.
The average particle size of the carrier is preferably 0.01 to 1 μm.

  Examples of the antigen or antibody against the target substance include the same antigens and antibodies as those described above.

In addition, the method for immobilizing an antigen or antibody against a target substance on a carrier may be carried out by bringing them into contact with each other in accordance with a conventional method such as physical adsorption by hydrophobic-hydrophobic interaction or chemical bonding using a water-soluble carbodiimide-based condensing agent. .
Specific methods include (1) a method in which the carrier is brought into contact with the solution containing the polymer used in the present invention, and the polymer is physically adsorbed on the surface of the carrier in the solution while leaving the dispersion medium, (2) Examples include a method in which a carrier is brought into contact with a solution containing a polymer used in the present invention, and then a dispersion medium is removed to form a dry film of the polymer on the surface of the carrier. More specifically, after dispersing the carrier in the solution containing the polymer used in the present invention, centrifugation is performed, the supernatant is removed, and the carrier is redispersed again with water or a buffer.

Moreover, it is preferable to use the said polymer 0.01-1000 mass parts with respect to 100 mass parts of support | carriers, and it is more preferable to use 0.1-500 mass parts.
Moreover, as a density | concentration in the solution of the said polymer at the time of coating, 0.01-50 mass% is preferable, and 0.01-10 mass% is more preferable. Even at such a low concentration, an excellent blocking effect is exhibited.

〔reagent〕
A reagent for use in detection of a target substance in a sample by in vitro diagnosis according to the present invention contains the above-described immobilized carrier. In the reagent of the present invention, the content of the immobilized carrier of the present invention is preferably 0.001 to 20% by mass, more preferably 0.01 to 10% by mass.
In addition to the immobilized carrier, the reagent of the present invention may contain a solvent and a blocking agent other than the polymer of the present invention, and one of these may be contained alone or in combination of two or more. May be. The blocking agent other than the polymer of the present invention is the same as described above, but the solvent is a phosphate buffer, glycine buffer, Good buffer, other than the solvent that may be contained in the blocking agent of the present invention, Examples include various buffer solutions such as a Tris buffer solution and an ammonia buffer solution.
The reagent of the present invention is particularly useful for detecting a target substance in a specimen by a latex agglutination method.

〔kit〕
A kit for use in detecting a target substance in a specimen by in vitro diagnosis according to the present invention is characterized by comprising at least the above-described reagent.
The kit of the present invention further comprises a reaction buffer (also referred to as a first reagent) containing albumin in addition to the reagent containing the immobilized carrier of the present invention (also referred to as a second reagent). preferable.
Examples of the albumin include serum albumin and may be treated with protease. The content of albumin in the first reagent is usually 0.001 to 5% by mass.
The first reagent may contain a solvent and a sensitizer for latex aggregation measurement. Examples of the solvent include an aqueous medium. Examples of the aqueous medium include the various buffers described above.
Examples of the sensitizer for measuring latex aggregation include polyvinyl alcohol and polyvinyl pyrrolidone.
Moreover, the kit of this invention may be equipped with positive control, negative control, serum dilution liquid, etc. other than the said 1st reagent and 2nd reagent. The medium for the positive control and negative control may be a serum or physiological saline containing no measurable target substance, or a solvent. Examples of the solvent include the above aqueous medium.

  The kit of the present invention can be used in the method for detecting a target substance of the present invention in the same manner as a kit for use in detecting a target substance in a specimen by normal in vitro diagnosis. In addition, the concentration of the target substance can be measured according to a conventional method. In particular, it is useful for detecting a target substance in a specimen by a latex agglutination method.

[Target substance detection method]
The method for detecting a target substance in a specimen by in vitro diagnosis according to the present invention is characterized by mixing the immobilized carrier and a specimen that may contain the target substance.

Further, the mixing of the carrier and the specimen is preferably performed within a pH range of 4.0 to 10. The mixing temperature is usually in the range of 25 to 45 ° C., and the mixing time is usually 1 to 20 minutes.
Moreover, it is preferable that this detection method uses a solvent. The solvent is the same as that which the reagent of the present invention may contain.
The concentration of the immobilized carrier of the present invention is preferably 0.001 to 5% by mass, more preferably 0.01 to 1% by mass in the reaction system.

  Then, the target substance in the specimen is detected by optically detecting the agglutination reaction resulting from the mixing of the carrier and the specimen, and the concentration of the target substance can also be measured. The optical detection of the agglutination reaction may be performed according to a conventional method using an optical instrument that can detect scattered light intensity, transmitted light intensity, absorbance, and the like.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples.

Each analysis condition in the examples is as follows.
<Molecular weight measurement>
Weight average molecular weight (Mw) and number average molecular weight (Mn) were measured using a TSKgel α-M column manufactured by Tosoh Corporation, flow rate: 0.5 ml / min, elution solvent: NMP solvent (H ₃ PO ₄ : 0.016M, LiBr: 0.030M), column temperature: Measured by gel permeation chromatography (GPC) using polystyrene as a standard under analysis conditions of 40 ° C.
<NMR spectrum>
^{The 13} C-NMR spectrum was measured by a model AVANCE 500 (500 MHz) manufactured by BRUKER using d6-DMSO as a solvent and an internal standard substance.

Example 1 Synthesis of Copolymer (N-1-1) A copolymer (N-1-1) was obtained according to the following synthesis route.

113 g of glycidyl methacrylate and 113 g of styrene, 6.8 g of 2,2′-azobis (isobutyronitrile) as a polymerization initiator, and 475 g of N, N-dimethylformamide were mixed and placed in a flask. Nitrogen was blown into this, the temperature was raised to 70 ° C., polymerized for 6 hours, and then cooled to room temperature. This solution was purified by reprecipitation with methanol and dried under reduced pressure to obtain a copolymer (S-1-1).
In the obtained copolymer (S-1-1), the content of repeating units derived from glycidyl methacrylate was 48 mol%, and the content of repeating units derived from styrene was 52 mol%. These contents were measured by ¹³ C-NMR.

Next, 10 g of the obtained copolymer (S-1-1), 32.1 g of thioglycerol, and 95 g of N, N-dimethylformamide were mixed and placed in a flask. The temperature was raised to 60 ° C. while blowing nitrogen, and 120 g of triethylamine was added as a catalyst, followed by reaction for 4 hours, and then cooled to room temperature. This solution was purified by reprecipitation with water and freeze-dried to obtain a copolymer (G-1-1).
Next, 10 g of the obtained copolymer (G-1-1) was dispersed in 85.5 g of water and put into a flask. To this, 4.5 g of 30% aqueous hydrogen peroxide solution was added and reacted at room temperature for 18 hours. The aqueous solution obtained was dialyzed to obtain a copolymer (N-1-1) (yield: 13%). When this copolymer (N-1-1) and water were mixed and the concentration was adjusted to 1% by mass, the copolymer (N-1-1) was dissolved in water.
Moreover, the number average molecular weight of the obtained copolymer (N-1-1) was 19000, the weight average molecular weight was 30000, and molecular weight distribution was 1.59.
The structure of the copolymer (N-1-1) was confirmed by ¹³ C-NMR.

Example 2 Synthesis of Copolymer (N-1-2) A copolymer (N-1-2) was obtained by the same synthesis route as in Example 1 above.
170 g of glycidyl methacrylate and 56.8 g of styrene, 6.8 g of 2,2′-azobis (isobutyronitrile) as a polymerization initiator, and 475 g of N, N-dimethylformamide were mixed and placed in a flask. Nitrogen was blown into this, the temperature was raised to 70 ° C., polymerized for 6 hours, and then cooled to room temperature. This solution was purified by reprecipitation with methanol and dried under reduced pressure to obtain a copolymer (S-1-2).
In the obtained copolymer (S-1-2), the content of repeating units derived from glycidyl methacrylate was 67 mol%, and the content of repeating units derived from styrene was 33 mol%. These contents were measured in the same manner as in Example 1.

  Next, 10 g of the obtained copolymer (S-1-2) and 44.7 g of thioglycerol and 95 g of N, N-dimethylformamide were mixed and placed in a flask. The temperature was raised to 60 ° C. while blowing nitrogen, and 167 g of triethylamine was added as a catalyst, followed by reaction for 4 hours, and then cooled to room temperature. This solution was purified by reprecipitation with water and freeze-dried to obtain a copolymer (G-1-2).

Subsequently, 10 g of the obtained copolymer (G-1-2) was dispersed in 84.4 g of water and put into a flask. To this, 5.6 g of 30% aqueous hydrogen peroxide solution was added and reacted at room temperature for 18 hours. The aqueous solution obtained was dialyzed to obtain a copolymer (N-1-2) (yield: 18%). When the copolymer (N-1-2) and water were mixed and the concentration was adjusted to 1% by mass, the copolymer (N-1-2) was dissolved in water.
Moreover, the number average molecular weight of the obtained copolymer (N-1-2) was 31000, the weight average molecular weight was 56000, and molecular weight distribution was 1.81.
The structure of the copolymer (N-1-2) was confirmed by ¹³ C-NMR.

Example 3 Synthesis of Copolymer (N-1-3) A copolymer (N-1-3) was obtained by the same synthesis route as in Example 1.
170 g of glycidyl methacrylate and 56.8 g of styrene, 2.27 g of 2,2′-azobis (isobutyronitrile) as a polymerization initiator and 450 g of ethyl acetate were mixed and placed in a flask. Nitrogen was blown into this, the temperature was raised to 70 ° C., polymerized for 8 hours, and then cooled to room temperature. This solution was purified by reprecipitation with methanol and dried under reduced pressure to obtain a copolymer (S-1-3).
In the obtained copolymer (S-1-3), the content of repeating units derived from glycidyl methacrylate was 67 mol%, and the content of repeating units derived from styrene was 33 mol%. These contents were measured in the same manner as in Example 1.

  Next, 10 g of the obtained copolymer (S-1-3) and 44.7 g of thioglycerol and 95 g of N, N-dimethylformamide were mixed and placed in a flask. The temperature was raised to 60 ° C. while blowing nitrogen, and 167 g of triethylamine was added as a catalyst, followed by reaction for 4 hours, and then cooled to room temperature. This solution was purified by reprecipitation with water and freeze-dried to obtain a copolymer (G-1-3).

Next, 10 g of the obtained copolymer (G-1-3) was dispersed in 84.4 g of water and put into a flask. To this, 5.6 g of 30% aqueous hydrogen peroxide solution was added and reacted at room temperature for 18 hours. The aqueous solution obtained was dialyzed to obtain a copolymer (N-1-3) (yield: 15%). When the copolymer (N-1-3) and water were mixed and the concentration was adjusted to 1% by mass, the copolymer (N-1-3) was dissolved in water.
Moreover, the number average molecular weight of the obtained copolymer (N-1-3) was 33000, the weight average molecular weight was 60000, and molecular weight distribution was 1.82.
The structure of the copolymer (N-1-3) was confirmed by ¹³ C-NMR.

  The HLB values (Oda formula) of the copolymers (N-1-1) to (N-1-3) obtained in Examples 1 to 3 are shown in Table 1 below. In addition, when the homopolymer which consists of the repeating unit (A) which a copolymer (N-1-1)-(N-1-3) has was synthesize | combined and 1 g was added to 100 g of pure waters, it was normal temperature (25 degreeC). Dissolved. Moreover, when the homopolymer which consists of the repeating unit (B) which a copolymer (N-1-1)-(N-1-3) has was synthesize | combined and 1 g was added to 100 g of pure waters, it was normal temperature (25 degreeC). It did not dissolve completely.

Example 4 Preparation of target substance detection reagent (1)
1 mL of 10% by weight aqueous solution of latex particles for immunodiagnostic (product number: G0305 (average particle size: 0.31 μm, surface COOH group content: 0.21 mmol / g-LTx, manufactured by JSR Corporation)) and HEPES buffer (0.05 M, pH 7.5) 9 mL (particle concentration = 1% by mass), 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride (manufactured by Dojin Chemical Co., Ltd.) It added so that a final concentration might be 0.05 mass%. Furthermore, 0.5 mL of a 10 mg / mL aqueous solution of an anti-CRP (C-reactive protein) antibody (rabbit) was added to this particle dispersion and stirred at room temperature for 3 hours to immobilize the antibody on the surface of the particles.
Thereafter, 0.5 mL of a 0.5% by mass aqueous solution of the copolymer (N-1-1) was added to the particle dispersion, and the mixture was slowly rotated and stirred at room temperature for 10 hours, followed by centrifugation at 15,000 rpm for 15 minutes. The particles were collected as a precipitate.
The particles were then resuspended in 10 mL of HEPES buffer (0.05 M, pH 7.5) and dispersed with ultrasound for 10 minutes. After this resuspension and dispersion operation was repeated once again, 200 mL of 10 mM HEPES buffer (pH 7.5) containing 0.02% by weight bovine serum albumin (BSA) was added to the particle dispersion to obtain a particle solid content of 0.05. The mass was adjusted to be mass%, the mixture was dispersed with ultrasonic waves for 10 minutes, and passed through a 0.8 μm disk filter.
Through a series of these operations, a dispersion (second reagent) of antibody-immobilized latex particles coated with the copolymer (N-1-1) was obtained.

Example 5 Preparation of target substance detection reagent (2)
In Example 4, a dispersion of antibody-immobilized latex particles was prepared in the same manner as in Example 4 except that the copolymer (N-1-2) was used instead of the copolymer (N-1-1). Obtained.

Example 6 Preparation of target substance detection reagent (3)
In Example 4, an antibody-immobilized latex particle dispersion was prepared in the same manner as in Example 4 except that the copolymer (N-1-3) was used instead of the copolymer (N-1-1). Obtained.

Comparative Example 1
In Example 4, a dispersion of antibody-immobilized latex particles was obtained in the same manner as in Example 4 except that the addition of the 0.5 mass% aqueous solution of copolymer (N-1-1) was not performed.

Comparative Example 2
In Example 4, a dispersion of antibody-immobilized latex particles was obtained in the same manner as in Example 4 except that bovine serum albumin (BSA) was used instead of the copolymer (N-1-1).

Test Example 1 Blocking effect evaluation test (1)
A 10 mM HEPES buffer solution (pH 7) containing 3 μL of physiological saline and 150 μL of the first reagent (0.1% by weight bovine serum albumin aqueous solution and 1.0% by weight polyvinyl alcohol (molecular weight 20,000)) in a plastic transparent cell. 5)) was added and the mixture was stirred uniformly and held for 5 minutes.
Next, after adding 150 μL of the dispersion liquid (second reagent) prepared in Examples 4 to 6 and Comparative Examples 1 and 2 to the cells and stirring uniformly, the absorbance after 50 seconds and the absorbance after 200 seconds passed. The difference was measured using a Hitachi 7180 automatic analyzer (use wavelength 570 nm and measurement temperature 37 ° C.). The results are shown in Table 2.

Test Example 2 blocking effect evaluation test (2)
First, instead of physiological saline, the difference in absorbance was measured in the same manner as in Test Example 1 except that five CRP antigen physiological saline solutions with different concentrations and known concentrations were used, respectively. A calibration curve was created from the relationship between the difference and the CRP antigen concentration.
Next, in place of physiological saline, test examples were used except that specimens whose CRP concentrations were known for 50 persons whose concentrations were accurately measured in advance by another method (these concentrations are respectively referred to as antigen concentration X) were used. The difference in absorbance was measured in the same manner as in 1, and the CRP antigen concentration was calculated from the obtained absorbance difference using the calibration curve prepared above (these calculated antigen concentrations are designated as antigen concentration Y, respectively).
Each CRP antigen concentration X was plotted on the X axis and each CRP antigen concentration Y was plotted on the Y axis, and the correlation coefficient R ² was determined for this function. The results are shown in Table 3.
Note that the closer the correlation coefficient R ² is to 1, the less the influence of excessive aggregation caused by the components contained in the specimen, and the better the blocking effect.

  From the results of Test Examples 1 and 2, it can be seen that the blocking agent of the present invention has an excellent noise reduction effect.

Claims (13)

A blocking agent used to prevent nonspecific adsorption to a carrier in in vitro diagnosis or to prevent the occurrence of aggregation of the carrier due to the nonspecific adsorption , having a repeating unit having a sulfinyl group in the side chain A blocking agent containing a polymer.   The blocking agent according to claim 1, wherein the repeating unit having a sulfinyl group in the side chain is hydrophilic. The blocking agent according to claim 1 or 2, wherein the repeating unit having a sulfinyl group in the side chain is represented by the following formula (2).

[In formula (2), R ¹ represents a hydrogen atom or a methyl group, R ² is a group -O-, a group * - (C = O) -O- , group * - (C = O) -NR ⁵ -, group * -NR ⁵ - (C = O) - (R ⁵ is a hydrogen atom or an organic group having 1 to 10 carbon atoms, and *, R ¹ in the formula (2) is attached Or a phenylene group, R ³ represents a direct bond or a divalent organic group having 1 to 24 carbon atoms, and R ⁴ represents an organic group having 1 to 10 carbon atoms. . ]   The blocking agent according to any one of claims 1 to 3, wherein the polymer further has a hydrophobic repeating unit.   The blocking agent according to claim 4, wherein the hydrophobic repeating unit is a repeating unit derived from one or more monomers selected from styrenes, (meth) acrylates and (meth) acrylamides.   The blocking agent according to any one of claims 1 to 5, wherein the polymer has an HLB value of 10 to 22.   A carrier on which an antigen or antibody against a target substance is immobilized, which is partially or entirely coated with a polymer having a repeating unit having a sulfinyl group in the side chain.   The immobilized carrier according to claim 7, wherein the carrier is latex particles.   A reagent for use in detecting a target substance in a specimen by in vitro diagnosis, comprising the immobilized carrier according to claim 7 or 8.   The reagent according to claim 9, which is used for detection of a target substance in a specimen by a latex agglutination method.   A kit for use in detecting a target substance in a sample by in vitro diagnosis, comprising at least the reagent according to claim 9 or 10.   A method for detecting a target substance in a specimen by in vitro diagnosis, comprising mixing the immobilized carrier according to claim 7 or 8 with a specimen that may contain the target substance. .   The detection method according to claim 12, which is a method for detecting a target substance in a specimen by a latex agglutination method.