WO2017090721A1 - 検体中の検出対象を定量する方法 - Google Patents
検体中の検出対象を定量する方法 Download PDFInfo
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- WO2017090721A1 WO2017090721A1 PCT/JP2016/084946 JP2016084946W WO2017090721A1 WO 2017090721 A1 WO2017090721 A1 WO 2017090721A1 JP 2016084946 W JP2016084946 W JP 2016084946W WO 2017090721 A1 WO2017090721 A1 WO 2017090721A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/58—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances
- G01N33/581—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving labelled substances with enzyme label (including co-enzymes, co-factors, enzyme inhibitors or substrates)
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
- G01N33/54313—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals the carrier being characterised by its particulate form
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/536—Immunoassay; Biospecific binding assay; Materials therefor with immune complex formed in liquid phase
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
- G01N33/54313—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals the carrier being characterised by its particulate form
- G01N33/54326—Magnetic particles
Definitions
- the present invention relates to a method for quantifying a detection target in a specimen.
- a trace component in a specimen is detected using an antigen-antibody reaction or the like.
- the specimen include specimens obtained from a living body such as various body fluids such as serum, plasma, urine, and lymph.
- Patent Document 1 discloses a first binding substance in which a stimulus-responsive substance and a first affinity substance for the detection target are combined, and a second substance having a charge.
- the specimen are mixed and placed under the aggregation condition of the stimulus-responsive substance, and the stimulus-responsive substance is dispersed in the mixture
- a method for detecting the presence or absence of a detection target based on the turbidity of a mixture.
- the stimulus-responsive substance when the detection target is present, the stimulus-responsive substance is inhibited and dispersed while being agglutinated, whereas when the detection target is not present, the stimulus-responsive substance is aggregated.
- the presence or absence of such aggregation inhibition is reflected in the turbidity of the mixture.
- the greater the amount of the detection target the more the stimulus-responsive substance is agglomerated and dispersed to lower the turbidity, and then the relationship between the detection target amount and the turbidity is reversed.
- the turbidity decreases from the initial value over time. This is because the agglomerated magnetic substance is solid-liquid separated by magnetic force, but higher detection sensitivity can be obtained by utilizing the difference between the maximum measured value and the measured value after that point. It has been.
- the present invention has been made in view of the above circumstances, and an object thereof is to provide a method capable of detecting and quantifying a detection target quickly and with high sensitivity.
- the present inventors have found that the degree of dispersion of the stimulus-responsive substance can be detected and quantified rapidly and with high sensitivity by determining the particle size of the suspension in the mixture,
- the present invention has been completed. Specifically, the present invention provides the following.
- a method for quantifying a detection target in a sample A mixing step of mixing a carrier particle carrying a stimulus-responsive substance and a first affinity substance for the detection target, and the specimen to prepare a mixture; A measurement step of placing the mixture under agglomeration conditions of the stimulus-responsive substance and measuring a particle size of a suspension in the mixture; Determining the amount of the detection target based on the particle diameter.
- the detection target can be quantified quickly and with high sensitivity.
- the method for quantifying a detection target in a sample of the present invention comprises a carrier particle carrying a stimulus-responsive substance and a first affinity substance for the detection target (hereinafter sometimes referred to as a first bound substance), a sample Mixing step for preparing a mixture, placing the mixture under agglutination conditions of the stimulus-responsive substance, measuring step for measuring the particle size of the suspension in the mixture, and the amount to be detected based on the particle size Determining step.
- sample> examples of the sample include various body fluids such as human or animal serum, plasma, urine, and lymph, biological materials such as feces, food and drinks, tap water, and samples collected from environments such as rivers.
- detection target> examples of targets that can be detected by the above detection methods include environmental pollutants, food pollutants, and substances used for clinical diagnosis.
- Such substances include dioxins, environmental hormones, pesticides, PCB (polychlorbiphenyl), organic mercury, prion fungus poison, puffer poison, antibiotics, fungicides, body fluids, urine, sputum, feces, etc.
- Human immunoglobulin G Human immunoglobulin M, human immunoglobulin A, human immunoglobulin E, human albumin, human fibrinogen (fibrin and their degradation products), ⁇ -fetoprotein (AFP), C-reactive protein (CRP) ), Myoglobin, carcinoembryonic antigen, hepatitis virus antigen, human chorionic gonadotropin (hCG), human placental lactogen (HPL), HIV virus antigen, allergen, bacterial toxin, bacterial antigen, enzyme, hormone (eg, human thyroid stimulation Hormone (TSH), a Surin, etc.), and agents, and the like.
- TSH human thyroid stimulation Hormone
- the carrier particle is not particularly limited as long as it is a substance that can be directly or indirectly bound to the stimulus-responsive substance and / or the first affinity substance and can be suspended.
- the carrier particles include organic fine particles such as silica and acrylic resin, particles made of metal, and the like, and particles made of silica are preferable.
- Silica should just be a particle
- Silica particles have a silanol group (Si—OH) on the surface of the particles, and are therefore highly hydrophilic, so that they are preferable in that they are easily reacted in water. Silica particles are also preferred because they are not toxic and are easy to handle and easy to manufacture.
- the carrier particles do not need to be a magnetic material attracted by magnetic force and affect the magnetic field. It may be a non-magnetic substance that does not affect
- the average refractive index of the carrier particles is preferably 1.3 or more, more preferably 1.3 or more and 4.0 or less, and more preferably 1.4 or more and 3.0 or less.
- the average refractive index of carrier particles is preferably in the above range.
- the average refractive index is a value measured at a wavelength of 589 nm and a temperature of 37 ° C. using an Abbe refractometer (DR-A1 manufactured by Atago Co., Ltd.) and a spectral light source.
- the average particle size of the carrier particles may be appropriately selected, and may be, for example, 0.05 to 1.0 ⁇ m, or 0.3 to 0.7 ⁇ m.
- the average particle diameter is a value measured by a scanning electron microscope (SEM).
- a stimulus-responsive substance is a substance that undergoes a structural change in response to an external stimulus and can adjust aggregation and dispersion.
- Examples of the stimulus include, but are not limited to, temperature change, light irradiation, acid or base addition (pH change), electric field change, and the like.
- a temperature-responsive polymer that can be aggregated and dispersed by temperature change can be used as the stimulus-responsive substance.
- the temperature-responsive polymer include a polymer having a lower critical solution temperature (hereinafter also referred to as LCST) and a polymer having an upper critical solution temperature (hereinafter also referred to as UCST).
- LCST lower critical solution temperature
- UCST upper critical solution temperature
- a polymer having a lower critical solution temperature with an LCST of 37 ° C. is completely dispersed in an aqueous solution having a temperature lower than the LCST, and can be agglomerated immediately when the water temperature is raised above the LCST.
- a polymer having an upper critical solution temperature with a UCST of 5 ° C. is completely dispersed in an aqueous solution having a temperature exceeding the UCST, and can be immediately aggregated when the water temperature is lowered below the UCST.
- Examples of the polymer having a lower critical solution temperature used in the present invention include Nn-propylacrylamide, N-isopropylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, N-acryloylpyrrolidine, N-acryloylpiperidine, N N substitution such as acryloylmorpholine, Nn-propylmethacrylamide, N-isopropylmethacrylamide, N-ethylmethacrylamide, N, N-dimethylmethacrylamide, N-methacryloylpyrrolidine, N-methacryloylpiperidine, N-methacryloylmorpholine Polymer composed of (meth) acrylamide derivative; hydroxypropyl cellulose, polyvinyl alcohol partially acetylated product, polyvinyl methyl ether, (polyoxyethylene-polyoxypro Len) block copolymers, polyoxyethylene alkylamine derivatives such as polyoxyethylene laurylamine; poly
- copolymers of these polymers and at least two of these monomers can also be used.
- a copolymer of N-isopropylacrylamide and Nt-butylacrylamide can also be used.
- another copolymerizable monomer may be copolymerized with the polymer within a range having a lower critical solution temperature.
- an elastin-derived polypeptide having a repeating sequence of a pentapolypeptide represented by Val-Pro-Gly-X-Gly (X is an amino acid other than proline) can be preferably used.
- a polymer having the upper critical solution temperature used in the present invention a polymer comprising at least one monomer selected from the group consisting of acryloylglycinamide, acryloylnipecotamide, acryloylasparagineamide, acryloylglutamineamide, and the like can be used. Moreover, the copolymer which consists of these at least 2 types of monomers may be sufficient.
- These polymers include other copolymerizable monomers such as acrylamide, acetylacrylamide, biotinol acrylate, N-biotinyl-N′-methacryloyl trimethylene amide, acryloyl sarcosine amide, methacryl sarcosine amide, acryloylmethyl uracil, etc. May be copolymerized within the range having the upper critical solution temperature.
- a substance such as a pH-responsive polymer that can be aggregated and dispersed by changing pH can be used as the stimulus-responsive substance.
- the pH at which the pH-responsive substance undergoes a structural change is not particularly limited, but is preferably pH 4 to 10, and preferably pH 5 to 9 from the viewpoint of suppressing a decrease in detection / quantification accuracy due to denaturation of carrier particles and specimens at the time of stimulation. More preferably.
- Examples of such a pH-responsive polymer include polymers containing groups such as carboxyl, phosphoric acid, sulfonyl and amino as functional groups. More specifically, (meth) acrylic acid, maleic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, phosphorylethyl (meth) acrylate, aminoethyl methacrylate, aminopropyl (meth) acrylamide, dimethylamino
- a monomer having a dissociating group such as propyl (meth) acrylamide may be polymerized, and the monomer having such a dissociating group and other vinyl monomers such as methyl (meta ) (Meth) acrylates such as acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, vinyl esters such as vinyl acetate and vinyl propionate, vinyl compounds such as styrene, vinyl chloride and N-viny
- the stimulus-responsive substance is not limited to the above-mentioned stimulus-responsive polymer.
- Japanese Patent No. 3693979, Japanese Patent No. 3916330, Japanese Patent Application Laid-Open No. 2002-85957, Japanese Patent No. 4071738, Japanese Patent No. 2869684 are disclosed.
- Hydrogels disclosed in Japanese Patent No. 2927601, Japanese Patent No. 3845249, and the like may be used.
- the first affinity substance is not particularly limited as long as it has affinity for the detection target.
- affinity refers to the property that a certain substance specifically binds to another substance.
- the first affinity substance include an antibody against the antigen when the detection target is an antigen, and an antigen against the antibody when the detection target is an antibody.
- glutathione when the detection target is a protein with a GST tag
- chelating agent coordinated with a metal ion when the detection target is a protein with a histidine tag
- a nucleic acid having a complementary sequence when the detection target is a nucleic acid Can be mentioned.
- the antibody may be any type of immunoglobulin molecule, and may be an immunoglobulin molecule fragment having an antigen binding site such as Fab.
- the antibody may be a monoclonal antibody or a polyclonal antibody.
- the second bound substance is added in addition to the first bound substance in the mixing step described later.
- This second binding substance is a combination of a hydrophilic substance and a second affinity substance for the detection target.
- hydrophilic substance A hydrophilic substance will not be specifically limited if it is a substance which has hydrophilicity with respect to the aqueous dispersion medium mentioned later.
- hydrophilic refers to the property that a substance has an affinity for an aqueous dispersion medium.
- the hydrophilic high molecular compound which has an electric charge is mentioned, for example, It is preferable that it is a polyanion or a polycation.
- the polyanion means a substance having a plurality of anion groups
- the polycation means a substance having a plurality of cation groups.
- polyanions include nucleic acids such as DNA and RNA.
- nucleic acids have the properties of polyanions due to the presence of a plurality of phosphodiester groups along the nucleic acid urn.
- the polyanion contains, as a polymerization component, a polypeptide having a large number of carboxylic acid functional groups (polypeptide consisting of amino acids such as glutamic acid and aspartic acid), polyacrylic acid, polymethacrylic acid, and acrylic acid or methacrylic acid.
- Polysaccharides such as polymers, carboxymethylcellulose, hyaluronic acid, and heparin are also included.
- examples of the polycation include polylysine, polyarginine, polyornithine, polyalkylamine, polyethyleneimine, and polypropylethyleneimine.
- the number of functional groups of the polyanion (carboxyl group) or polycation (amino group) is preferably 25 or more.
- the second affinity substance a substance that can bind non-competitively to the detection target at a site different from that of the first affinity substance is used.
- the detection target is an antigen
- the second affinity substance is a monoclonal antibody or a polyclonal that recognizes an antigen determinant to be detected that recognizes an antigenic determinant different from the first affinity substance in the antigen. It is an antibody.
- the first binding substance is prepared by binding the stimulus-responsive substance and the first affinity substance directly or indirectly to the carrier particles.
- This bonding method is not particularly limited.
- a method of binding via a reactive functional group is exemplified, and a method well known in the art. You can go.
- the binding between the stimulus-responsive substance and the first affinity substance is performed by binding both the stimulus-responsive substance and the first affinity substance to substances that are compatible with each other (for example, , Avidin and biotin, glutathione and glutathione S transferase), and the stimulus-responsive substance and the first affinity substance are bound via these substances.
- substances that are compatible with each other for example, , Avidin and biotin, glutathione and glutathione S transferase
- biotin is bound to a stimulus-responsive substance by adding biotin or the like to a polymerizable functional group such as methacryl or acryl to form an addition polymerizable monomer. It can be carried out by copolymerizing with other monomers.
- the binding of avidin or the like to the first affinity substance can be performed according to a conventional method.
- the biotin-binding stimulus-responsive substance and the avidin-bonded first affinity substance are mixed, the stimulus-responsive substance and the first affinity substance are bonded through the binding between avidin and biotin.
- a monomer having a functional group such as carboxyl, amino, or epoxy is copolymerized with another monomer during the production of the polymer or the like, and the antibody affinity substance is passed through this functional group according to a method well known in the art.
- a method of binding melon gel, protein A, protein G to a polymer can be used.
- a monomer having a functional group such as carboxyl, amino, or epoxy may be copolymerized with another monomer during the production of the polymer, and the first antibody against the antigen to be detected may be directly bonded to these functional groups according to a conventional method. Good.
- the first affinity substance and the stimulus-responsive polymer may be bound to the fine-particle magnetic substance.
- the first binding substance may be purified by subjecting the first affinity substance to conditions where the stimulus-responsive polymer aggregates and then separating by centrifugation.
- the first bound substance is purified by a method in which a particulate magnetic substance is bound to the stimulus-responsive polymer, and further the first affinity substance is bound, and then the magnetic substance is recovered by applying a magnetic force. Also good.
- the fine magnetic substance can be bonded to the stimulus-responsive polymer via a reactive functional group, or a polymerizable unsaturated bond is introduced into the active hydrogen or polyhydric alcohol on the polyhydric alcohol in the magnetic substance.
- the graft polymerization may be carried out by a method known in the art such as graft polymerization (for example, ADV.Polym.Sci., Vol.4, p111, 1965, J. Polymer Sci., Part-A, 3, p1031). 1965).
- the second binding substance is prepared by directly or indirectly binding the hydrophilic substance and the second affinity substance.
- substances having affinity for each other for example, avidin and biotin, glutathione and glutathione S transferase
- the hydrophilic substance and the second affinity substance are indirectly bonded through these substances.
- hydrophilic substance and the second affinity substance When the hydrophilic substance and the second affinity substance are directly bonded, they may be bonded through a functional group.
- a functional group the method of Gosh et al. (Ghosh et al: Bioconjugate Chem. , 1, 71-76, 1990). Specifically, there are the following two methods.
- a mercapto group also called a sulfhydryl group
- a 6-maleimidohexanoic acid succinimide ester for example, “EMCS (trade name)” (Dojin) is introduced into an antibody.
- the maleimide group is introduced by reacting Chemical). Next, these two substances are bonded through a mercapto group and a maleimide group.
- a mercapto group is introduced at the 5 ′ end of the nucleic acid in the same manner as in the first method, and N, N-1,2-phenylene diene which is a homobifunctional reagent is further introduced into this mercapto group.
- N, N-1,2-phenylene diene which is a homobifunctional reagent is further introduced into this mercapto group.
- maleimide By reacting with maleimide, a maleimide group is introduced at the 5 ′ end of the nucleic acid, while a mercapto group is introduced into the antibody.
- these two substances are bonded through a mercapto group and a maleimide group.
- nucleic Acids Research Vol. 15 5275 (1987) and Nucleic Acids Research Vol. 16 3671 (1988) are known. Yes. These techniques can be applied to the binding of nucleic acids and antibodies.
- a mercapto group is first introduced into the 5'-terminal hydroxyl group of an oligonucleotide by reacting the oligonucleotide with cystamine, carbodiimide and 1-methylimidazole. After purifying the oligonucleotide with a mercapto group introduced, it is reduced with dithiothreitol, followed by the addition of 2,2'-dipyridyl disulfide to introduce a pyridyl group via a disulfide bond at the 5 'end of the oligonucleotide. To do.
- a mercapto group is introduced by reacting iminothalylene.
- the oligonucleotide introduced with the pyridyl disulfide group and the protein introduced with the mercapto group are mixed, and the pyridyl group and the mercapto group are specifically reacted to bind the protein and the oligonucleotide.
- dithio-bis-propionic acid-N- Hydroxysuccinimide ester (abbreviation: dithio-bis-propionyl-NHS) is reacted.
- dithiothreitol is added to reduce the disulfide bond in the dithio-bis-propionyl-NHS molecule and introduce a mercapto group at the 3 'end of the oligonucleotide.
- a heterobifunctional cross-linking agent As shown in JP-A-5-48100 is used. First, it has a first reactive group (succinimide group) that can react with a functional group (for example, an amino group) in a protein, and a second reactive group (for example, a maleimide group) that can react with a mercapto group.
- a first reactive group succinimide group
- a second reactive group for example, a maleimide group
- a second reactive group is introduced into the protein to obtain a preactivated protein reagent.
- the protein reagent thus obtained is covalently bound to the mercapto group of the thiolated polynucleotide.
- the method for quantifying the detection target of the present invention comprises mixing a carrier particle (first bound substance) carrying a stimulus-responsive substance and a first affinity substance for the detection target, and a specimen to prepare a mixture.
- the first combined substance and the specimen are mixed in a container to prepare a mixture.
- it is preferable to mix the second binding substance together.
- it may be dispersed in an aqueous dispersion medium as necessary.
- the aqueous dispersion medium no absorption is observed with respect to the wavelength of a laser used in an apparatus using a dynamic light scattering method, which will be described later, and there is no influence of dissolution, swelling, etc. on the first bonded substance.
- Any material having a refractive index different from that of the first combination and the second combination may be used.
- examples of the dispersion medium include Tris-HCl buffer, phosphate buffer, and borate buffer.
- the mixture is placed under agglomeration conditions where the stimulus responsive substance agglomerates.
- the stimulus-responsive substance is dispersed and inhibited by aggregation by the charge portion or the hydrophilic portion of the detection target.
- the stimulus-responsive substance aggregates without being inhibited from aggregation.
- the container containing the mixture may be transferred to a thermostatic bath at a temperature at which the temperature responsive polymer aggregates.
- a temperature-responsive polymer having an upper critical solution temperature (hereinafter sometimes abbreviated as “UCST”) and a polymer having a lower critical solution temperature (hereinafter sometimes abbreviated as “LCST”).
- UCST upper critical solution temperature
- LCST lower critical solution temperature
- the temperature-responsive polymer can be agglomerated by transferring the container containing the mixed solution to a constant temperature bath of 37 ° C. or higher. .
- the temperature-responsive polymer can be agglomerated by moving the container containing the mixed solution to a thermostatic bath of less than 5 ° C. .
- the aggregation of the temperature-responsive polymer may be performed before the first bound substance and the target to be detected, or may be performed in parallel, but the latter is preferable because the processing time can be shortened.
- the lower critical solution temperature and the upper critical solution temperature can be determined as follows, for example. First, a sample is put into a cell of an absorptiometer and the sample is heated at a rate of 1 ° C./min. During this time, the change in transmittance at 550 nm is recorded. Here, when the transmittance when the polymer is transparently dissolved is 100% and when the transmittance when the polymer is completely aggregated is 0%, the temperature at which the transmittance is 50% is obtained as LCST.
- an acid solution or an alkali solution may be added to a container containing the mixture.
- an acid solution or an alkaline solution is added to a container containing a mixture outside the pH range where the pH-responsive polymer undergoes a structural change, and the pH-responsive polymer is brought into a pH range where the pH-responsive polymer undergoes a structural change. Change it.
- an acid solution may be added to a container containing a mixture dispersed at a pH of more than 5 so that the pH is 5 or less.
- an alkaline solution may be added to a container containing a mixture dispersed at a pH lower than 10 so that the pH becomes 10 or higher.
- the pH at which the pH-responsive polymer undergoes a structural change is not particularly limited, but is preferably pH 4 to 10, and more preferably pH 5 to 9.
- the photoresponsive polymer when a photoresponsive polymer is used, light having a wavelength capable of aggregating the photoresponsive polymer may be irradiated onto a container containing a mixed solution.
- the preferred light for aggregation varies depending on the type and structure of the photoresponsive functional group contained in the photoresponsive polymer, but in general, ultraviolet light or visible light having a wavelength of 190 to 800 nm can be suitably used.
- the strength is preferably 0.1 to 1000 mW / cm 2 .
- the photoresponsive polymer is one that hardly causes dispersion when irradiated with light used for measuring the particle diameter, in other words, aggregates, in that the measurement accuracy can be improved.
- the measurement accuracy can be improved by shortening the irradiation time.
- the particle size of the suspension in the mixture can be measured with a commercially available particle size distribution measuring device or the like.
- Particle size distribution measurement methods include dynamic light scattering, optical microscopy, confocal laser microscopy, electron microscopy, atomic force microscopy, static light scattering, laser diffraction, centrifugal sedimentation, and electrical pulse measurement. Methods, chromatographic methods, ultrasonic attenuation methods and the like are known.
- the dynamic light scattering particle size distribution measuring device may be a discrete method, but is preferably not a discrete measuring device from the viewpoint of continuously and smoothly measuring the particle diameter.
- the “particle diameter by dynamic light scattering method” is a concept that includes not only primary particles but also secondary particles formed by aggregation of primary particles, as measured by the dynamic light scattering method. This is an index for evaluating the degree of dispersion of the complex in which the stimulus-responsive substance of the combined substance is aggregated. Examples of a commercially available measuring device using dynamic light scattering include a dynamic light scattering type particle size distribution measuring device [device name: ZETA SIZER Nano-ZS; manufactured by Malvern].
- the measurement time (aggregation time) of the particle size of the suspension may be set as appropriate from the viewpoint of required speed and sensitivity. When quickness is required, it may be performed before the time required for the turbidity (absorbance) of the solution in which the detection target is not present to reach the maximum value after being placed under the aggregation condition. In the method of quantifying the detection target by measuring the particle size, the change in the particle size appears greatly from the very early stage under the aggregation conditions. Therefore, for example, as shown in FIG. 3, the present invention detects a detection target with high detection sensitivity before 600 seconds when the turbidity (absorbance) of a solution in which no detection target exists (zero) is maximum. Is possible.
- the measurement should be performed beyond the above time (the time required for the turbidity (absorbance) of the solution in which the detection target is not present to reach the maximum value after being placed under the aggregation condition). Good.
- a sample (blood, etc.) suspected of containing a detection target contains many types and a large amount of contaminants, but the measured particle size is greatly influenced by the contaminants in the detection target. It is not a thing. For this reason, it is not always necessary to perform a preliminary procedure of removing impurities before measurement.
- the data may be related to the amount of two or more detection targets, and is preferably related to the amount of three or more detection targets.
- the amount of the detection target in the sample can be calculated. For example, when a polymer having a lower critical solution temperature with an LCST of 37 ° C. is used as the stimulus responsive substance, the container containing the mixed solution is transferred to a constant temperature bath at 37 ° C. or higher to detect the antigen to be detected. Depending on the concentration, changes in the particle size as shown in FIG. 1 are observed.
- the result shown in FIG. 1 is the measurement performed on the same conditions as the measurement process demonstrated in Example 1 mentioned later except the density
- the first binding substance and the detection target are mixed, if the detection target exists, the first affinity substance binds to the detection target, and the charge part or the hydrophilic part of the detection target has the first affinity.
- the charge portion or the hydrophilic portion is arranged in the vicinity of the stimulus responsive substance, and aggregation of the stimulus responsive substance in response to the stimulus is inhibited.
- the stimulus-responsive substance aggregates without being inhibited from aggregation. Therefore, the smaller the amount of the detection target, the more the aggregation of the stimulus-responsive substance in the mixture proceeds with time, and the particle diameter of the suspension increases with time.
- the method of quantifying the detection target based on the particle size of the suspension has a change in the particle size compared to the case of quantifying the detection target based on the turbidity of the suspension. Since it appears from a fast stage, high detection sensitivity can be obtained even when the concentration of the detection target is small.
- a step of solid-liquid separation of the aggregates of the carrier particles (first bound material) is not necessarily required before the determination step. Therefore, the measurement time can be greatly shortened.
- the first binding substance, the second binding substance, and the detection target are mixed, when the detection target exists, the first affinity substance and the second affinity substance are bound to the detection target, and the carrier
- the charged portion or hydrophilic portion to be detected approaches the stimulus-responsive substance bound to the particle or the first affinity substance.
- the charged or hydrophilic portion bound to the second affinity substance approaches the stimulus-responsive substance bound to the carrier particles or the first affinity substance.
- the charge portion or the hydrophilic portion is disposed in the vicinity of the stimulus responsive substance, and aggregation of the stimulus responsive substance in response to the stimulus is inhibited.
- the stimulus-responsive substance aggregates without being inhibited from aggregation.
- the second binding substance may be further mixed in addition to the first binding substance.
- the method of quantifying the detection target based on the particle diameter of the suspension can be quantified more rapidly and with higher sensitivity than when the detection target is detected based on the turbidity of the suspension.
- an antibody (clone: 195 mouse, mouse IgG, manufactured by Leinco Technology, Inc.) as a first affinity substance for human thyroid-stimulating hormone (TSH) as a detection target is obtained by using a well-known sulfo-NHS-Biotin method. Biotinylated by (Asahi Techno Glass Co., Ltd.) to prepare a biotin-labeled anti-TSH beta antibody.
- Thermo-Max LSA Streptavidin (0.4% by mass) manufactured by Magnabeat Co., Ltd., which is a finely divided magnetic substance to which streptavidin is bound, is placed in a 1.5 mL microtube, and this microtube is heated to 42 ° C.
- the Thermo-Max LSA Streptavidin was aggregated and recovered with a magnet, and then the supernatant was removed.
- 250 ⁇ L of TBS buffer (20 mM Tris-HCl, 150 mM NaCl, pH 7.5) was added, and the aggregate was dispersed by cooling.
- an antibody (clone: 176 mouse, mouse IgG, manufactured by Leinco Technology, Inc., 1 mg / mL) as a second affinity substance for human thyroid stimulating hormone (TSH) as a detection target, 6 mg of 2-mercaptoethanol And reacted at 37 ° C. for 120 minutes.
- TSH human thyroid stimulating hormone
- the labeled antibody was prepared by gel filtration using This labeled antibody (this antibody is also called a polyacrylic acid anti-TSH ⁇ antibody conjugate) is 0.5% (w / v) BSA (manufactured by Sigma), 0.5% (w / v) Tween (registered trademark). ) A second conjugate was prepared by diluting with 20 / PBS (pH 7.4), 10 mM EDTA in water to a protein concentration of 4 ⁇ g / mL.
- the maleimidated sodium polyacrylate was prepared as follows. First, 2 g of acrylic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 2-aminoethanethiol (manufactured by Wako Pure Chemical Industries, Ltd.) 0. 021 g and 0.023 g of azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd.) were dissolved in 50 mL of N, N-dimethylformamide, followed by nitrogen substitution for 1 hour. Thereafter, a polymerization reaction was carried out at 70 ° C. for 7 hours.
- reaction solution was concentrated under reduced pressure to 10 mL, and re-precipitated with diethyl ether until the viscous product became powdery.
- the white precipitate was filtered, and further dried overnight in a vacuum dryer to obtain amino group-terminated polyacrylic acid (yield 1.5 g).
- amino group-terminated polyacrylic acid was maleimidized.
- a 50 mL eggplant flask equipped with a nitrogen gas inlet tube and a stirrer was charged with 0.5 g of amino group-terminated polyacrylic acid and 10 mL of N, N-dimethylformamide.
- Example preparation Human thyroid stimulating hormone (TSH; manufactured by Aspen Bio Pharma, Inc., activity 8.5 IU / mg, WHO 80/558) was dissolved in PBS buffer (pH 7.4) to a concentration of 30 ⁇ g / mL. A sample obtained by diluting this solution with Vitros TSH calibrator 1 (TSH: 0 mIU / L, manufactured by Ortho Clinical Diagnostics) to 1 ng / mL was used as a sample.
- TSH Human thyroid stimulating hormone
- an antibody (clone: 195 mouse, mouse IgG, manufactured by Leinco Technology, Inc.) as a first affinity substance for human thyroid-stimulating hormone (TSH) as a detection target is obtained by using a well-known sulfo-NHS-Biotin method. Biotinylated by (Asahi Techno Glass Co., Ltd.) to prepare a biotin-labeled anti-TSH beta antibody.
- Thermo-Max LSA Streptavidin (0.4% by mass) manufactured by Magnabeat Co., which is a particulate magnetic material to which streptavidin is bound, is placed in a 1.5 mL microtube, and this microtube is heated to 42 ° C.
- Thermo-Max LSA Streptavidin was aggregated and recovered with a magnet, and then the supernatant was removed.
- 250 ⁇ L of TBS buffer (20 mM Tris-HCl, 150 mM NaCl, pH 7.5) was added, and the aggregate was dispersed by cooling.
- Example preparation Human thyroid stimulating hormone (TSH; manufactured by Aspen Bio Pharma, Inc., activity 8.5 IU / mg, WHO 80/558) was dissolved in PBS buffer (pH 7.4) to a concentration of 30 ⁇ g / mL. A sample obtained by diluting this solution with Vitros TSH calibrator 1 (TSH: 0 mIU / L, manufactured by Ortho Clinical Diagnostics) to 1 ng / mL was used as a sample.
- TSH Human thyroid stimulating hormone
- a neodymium permanent magnet (manufactured by Seiko Sangyo Co., Ltd.) having a size of 5 mm ⁇ 9 mm ⁇ 2 mm was attached outside the optical path of a widely used semi-micro cell for a spectrophotometer. This cell was placed in a visible ultraviolet spectrophotometer “UV-3101PC” (manufactured by Shimadzu Corporation) equipped with a cell temperature controller, and kept at 37 ° C. for 10 minutes or more.
- UV-3101PC visible ultraviolet spectrophotometer
- the above mixture is dispensed into the cell, zero-corrected according to the instruction manual attached to the spectrophotometer, and continuously with turbidity (absorbance Abs) at a slit width of 10 mm for 35 minutes using light with a wavelength of 420 nm. ) was measured. Similarly, the turbidity (absorbance Abs) was also measured for the mixed solution serving as a negative control. The result is shown in FIG. 2 together with the result of the example.
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Abstract
Description
刺激応答性物質及び前記検出対象に対する第1の親和性物質を担持する担体粒子と、前記検体とを混合し、混合物を調製する混合工程と、
前記混合物を前記刺激応答性物質の凝集条件下におき、前記混合物中の懸濁物の粒子径を測定する測定工程と、
前記粒子径に基づき、前記検出対象の量を決定する決定工程と、を有する方法。
(2)懸濁物に含まれる担体粒子の凝集物を固液分離する工程を、前記決定工程の前に含まない(1)記載の方法。
<検体>
検体としては、人又は動物の血清、血漿、尿、リンパ液等の各種体液及び糞便等の生物学的物質、飲食品、水道水、並びに河川等の環境から採取した試料等が挙げられる。
<検出対象>
以上の検出方法で検出できる対象としては、例えば環境汚染物質、食品汚染物質及び臨床診断に利用される物質が挙げられる。このような物質としては、具体的には、ダイオキシン、環境ホルモン、農薬、PCB(polychlorbiphenyl)、有機水銀等、プリオンカビ毒、フグ毒、抗生物質、防カビ剤、体液、尿、喀痰、糞便中等に含まれるヒトイムノグロブリンG、ヒトイムノグロブリンM、ヒトイムノグロブリンA、ヒトイムノグロブリンE、ヒトアルブミン、ヒトフィブリノーゲン(フィブリン及びそれらの分解産物)、α-フェトプロテイン(AFP)、C反応性タンパク質(CRP)、ミオグロビン、ガン胎児性抗原、肝炎ウイルス抗原、ヒト絨毛性ゴナドトロピン(hCG)、ヒト胎盤性ラクトーゲン(HPL)、HIVウイルス抗原、アレルゲン、細菌毒素、細菌抗原、酵素、ホルモン(例えば、ヒト甲状腺刺激ホルモン(TSH)、インスリン等)、及び薬剤等が挙げられる。
[担体粒子]
担体粒子は、刺激応答性物質及び/又は第1の親和性物質が直接又は間接に結合可能な物質で、懸濁可能な物質であれば特に限定されない。担体粒子としては、シリカ、アクリル樹脂等の有機微粒子、金属からなる粒子等が挙げられ、シリカからなる粒子が好ましい。シリカは、二酸化ケイ素を主成分とする粒子であればよく、石英又は水晶からなる粒子を含み、シリカと通称されるものからなる粒子であってよい。シリカ粒子は、粒子表面にシラノール基(Si-OH)を有していることから、親水性が高いので、水中で反応させやすい点で好ましい。シリカ粒子は、また、毒性がないので、取扱いが容易であり、製造も容易である点でも好ましい。
刺激応答性物質は、外的な刺激に応答して構造変化を起こし、凝集及び分散を調整できる物質である。刺激としては、特に限定されないが、温度変化、光の照射、酸又は塩基の添加(pHの変化)、電場変化等が挙げられる。
第1の親和性物質は、検出対象に対して親和性を有する物質であれば、特に限定されない。ここで、「親和性」とは、ある物質が他の物質と特異的に結合する性質をいう。第1の親和性物質としては、例えば検出対象が抗原である場合は該抗原に対する抗体、検出対象が抗体である場合は該抗体に対する抗原である。例えば、検出対象がGSTタグ付きのタンパク質である場合はグルタチオン、検出対象がヒスチジンタグ付のタンパク質の場合は金属イオン配位したキレート剤、検出対象が核酸の場合は相補的な配列をもつ核酸が挙げられる。
第2の結合物は、より高い検出感度を得るために、後述する混合工程において、上記第1の結合物に加えて添加されるものである。この第2の結合物は、親水性物質と検出対象に対する第2の親和性物質とを結合したものである。
親水性物質は、後述する水性分散媒に対して親水性を有する物質であれば特に限定されない。ここで、「親水性」とはある物質が水性分散媒に対して親和力をもつ性質をいう。親水性物質としては、例えば、電荷を有する親水性の高分子化合物が挙げられ、ポリアニオン又はポリカチオンであることが好ましい。ポリアニオンとは複数のアニオン基を有する物質を意味し、ポリカチオンとは複数のカチオン基を有する物質を意味する。ポリアニオンの例として、DNA及びRNA等の核酸が挙げられる。これらの核酸は、核酸骨恪に沿って複数個のホスホジエステル基が存在することにより、ポリアニオンの性質を有する。また、ポリアニオンには、多数のカルボン酸官能基を含むポリペプチド(グルタミン酸、アスパラギン酸等のアミノ酸からなるポリペプチド)、ポリアクリル酸、ポリメタクリル酸、及びアクリル酸やメタクリル酸を重合成分として含有するポリマー、カルボキシメチルセルロース、ヒアルロン酸、及びヘパリン等の多糖等も含まれる。一方、ポリカチオンの例としては、ポリリジン、ポリアルギニン、ポリオルニチン、ポリアルキルアミン、ポリエチレンイミンやポリプロピルエチレンイミン等が挙げられる。なお、ポリアニオン(カルボキシル基)やポリカチオン(アミノ基)の官能基数は、25個以上が好ましい。
第2の親和性物質は、検出対象に対して、第1の親和性物質とは異なる部位にて非競合的に結合できる物質を用いる。例えば、検出対象が抗原である場合、第2の親和性物質は、該抗原において第1の親和性物質とは異なる抗原決定基を認識する検出対象の抗原決定機を認識するモノクロナール抗体又はポリクロナール抗体である。
[第1の結合物の作製方法]
第1の結合物は、担体粒子に刺激応答性物質と第1の親和性物質とを直接又は間接に結合することによって作製する。この結合方法は、特に限定されないが、例えば、担体粒子と刺激応答性物質とを直接的に結合する場合は、反応性官能基を介して結合する方法が挙げられ当技術分野で周知の方法で行ってよい。
第2の結合物は、親水性物質と第2の親和性物質とを直接又は間接に結合することによって作製する。特に限定されないが、例えば、親水性物質側及び第2の親和性物質(例えば、第2の抗体)側の双方に、互いに親和性の物質(例えば、アビジン及びビオチン、グルタチオン及びグルタチオンSトランスフェラーゼ)を結合させ、これら物質を介して親水性物質及び第2の親和性物質を間接的に結合させる。
本発明の検出対象を定量する方法は、刺激応答性物質及び検出対象に対する第1の親和性物質を担持する担体粒子(第1の結合物)と、検体とを混合し、混合物を調製する混合工程と、混合物を刺激応答性物質の凝集条件下におき、混合物中の懸濁物の粒子径を測定する測定工程と、粒子径に基づき、検出対象の量を決定する決定工程とを有する。
まず、第1の結合物と検体とを容器内で混合し、混合物を調製する。また、より高い検出感度が必要な場合には、第2の結合物も併せて混合することが好ましい。混合物を調製する際には必要に応じて水性分散媒に分散させるとよい。水性分散媒には、後述する動的光散乱法を用いた装置で使用するレーザーの波長に対して吸収を認めず、第1の結合物に対して溶解、膨潤等の影響を与えず、第1の結合物及び第2の結合物と異なった屈折率を有しているものであればよい。例えば、分散媒としては、トリス塩酸バッファー、リン酸バッファー、ホウ酸バッファー等が挙げられる。
上記混合物を刺激応答性物質が凝集する凝集条件下におく。検出対象が存在する場合には、刺激応答性物質が検出対象の電荷部分又は親水性部分によって凝集阻害されて分散する。一方、検出対象が存在しない場合には刺激応答性物質が凝集阻害されず凝集することになる。
(相関式)
上記測定工程と同一の条件における、検出対象の量と懸濁物の粒子径との相関式を作成する。この相関式を構成する検出対象の量と懸濁物の粒子径との測定には、データが多いほどに信頼性の高い相関式が得られる。そこでデータは、2以上の検出対象の量に関するものであればよく、3点以上の検出対象の量に関するものであることが好ましい。
上述した測定工程で得られた懸濁物の粒子径の測定値を、作成した相関式に代入することによって、検体中の検出対象の量を算出できる。例えば、刺激応答性物質として、LCSTが37℃である下限臨界溶液温度を有するポリマーを用いた場合には、混合液の入った容器を37℃以上の恒温槽に移すことで、検出対象の抗原濃度に応じて、図1に示すような粒子径の変化がみられる。なお、図1に示す結果は、ビオチン標識抗TSHベータ抗体の濃度が異なる以外は、後述する実施例1で説明する測定工程と同一の条件下で行われた測定である。
第1の結合物と検出対象とを混合すると、検出対象が存在する場合、この検出対象に第1の親和性物質が結合し、検出対象の電荷部分又は親水性部分が、第1の親和性物質に結合した刺激応答性物質に接近する。これにより電荷部分又は親水性部分が刺激応答性物質の近傍に配置され、刺激に応答した刺激応答性物質の凝集が阻害される。一方、検出対象が存在しない場合、刺激応答性物質が凝集阻害されず凝集することになる。そのため、検出対象の量が少ないほど、混合物中の刺激応答性物質の凝集が経時で進み、懸濁物の粒子径が経時で大きくなる。図1及び図3の比較からわかるように、懸濁物の粒子径に基づき検出対象を定量する方法は、懸濁物の濁度に基づき検出対象を定量する場合に比べ、粒子径の変化が速い段階から現れるため、検出対象の濃度が小さい場合においても高い検出感度を得ることができる。また、懸濁物の濁度に基づき検出対象を定量する場合のように、決定工程の前に、担体粒子(第1の結合物)の凝集物を固液分離する工程が必ずしも必要ない。よって、測定時間の大幅な短縮が可能となる。
[第1の結合物の調製]
まず、検出対象としてのヒト甲状腺刺激ホルモン(TSH)に対する第1の親和性物質としての抗体(クローン:195マウス、マウスIgG、Leinco Technology,Inc.製)を、従来周知のsulfo-NHS-Biotin法(旭テクノグラス社)によりビオチン化し、ビオチン標識抗TSHベータ抗体を調製した。
まず、検出対象としてのヒト甲状腺刺激ホルモン(TSH)に対する第2の親和性物質としての抗体(クローン:176マウス、マウスIgG、Leinco Technology,Inc.製、1mg/mL)1mLに2-メルカプトエタノール6mgを加え、37℃で120分反応させた。反応後、Slide-A-Lyzer(商品名) 透析カセット、10K MWCO(Pierce)により、PBSバッファー500mLに対して透析し、過剰の2-メルカプトエタノールを除き、限界排除分子量10000の限外濾過膜(MILLIPORE社製[Amicon Ultra-4 Ultracel 100k])を用いて0.5mLに濃縮し、マウス抗TSHα抗体の還元抗体を得た。この還元抗体0.5mLと100μLマレイミド化ポリアクリル酸ナトリウム(33mgをPBSバッファー1mLに溶解したもの)とを4℃で1晩反応させ、続いてSuperdex-200 10/300GL(GEヘルスケア社製)を用いてゲル濾過することで、標識抗体を作成した。この標識抗体(この抗体は、ポリアクリル酸抗TSHα抗体結合物ともいう。)を0.5%(w/v)BSA(シグマ社製)、0.5%(w/v)Tween(登録商標)20/PBS(pH7.4)、10mM EDTAの水溶液でタンパク質濃度4μg/mLに希釈することで、第2の結合物を調製した。
まず、窒素ガス導入管、温度計、及び撹拌装置を付した100mLの三口フラスコ内で、アクリル酸(和光純薬工業社製)2g、2-アミノエタンチオール(和光純薬工業社製)0.021g、及びアゾビスイソブチロニトリル(和光純薬工業社製)0.023gをN,N-ジメチルホルムアミド50mLに溶解し、1時間窒素置換を行った。その後、70℃で7時間重合反応を行った。得られた反応液を、10mLまで減圧濃縮し、粘稠状の物が粉状になるまでジエチルエーテルで再沈殿を行った。白色沈殿をろ過し、さらに真空乾燥機で1晩乾燥することで、アミノ基末端ポリアクリル酸を得た(収量1.5g)。次にアミノ基末端ポリアクリル酸をマレイミド化した。窒素ガス導入管、及び撹拌装置を付した50mLのナスフラスコに、アミノ基末端ポリアクリル酸0.5g及びN,N-ジメチルホルムアミド10mLを入れ、溶解した。そこにEMCS(N-(6-マレイミドカプロイロキシ)スクシンイミド)(同仁化学研究所社製)3mgを加え、一晩反応した。得られた反応液を、1mLまで減圧濃縮し、粘稠な物が粉状になるまでジエチルエーテルで再沈殿を行った。白色沈殿をろ過し、さらに真空乾燥機で、1晩乾燥しマレイミド基末端ポリアクリル酸を得た。分子量は約130000(東ソー社製、TSKgel Super AW3000、6mm ID.×150mm、移動相0.1M 硝酸ナトリウム)であり、収量は0.4gであった。
ヒト甲状腺刺激ホルモン(TSH;Aspen Bio Pharma,Inc.製、活性8.5IU/mg、WHO80/558)をPBSバッファー(pH7.4)に30μg/mLとなるように溶解した。この溶液をビトロスTSHキャリブレータ1(TSH:0mIU/L、オーソ・クリニカル・ダイアグノスティックス社製)で1ng/mL、となるよう希釈したものを試料とした。
第1の結合物150μL及び第2の結合物120μLをマイクロチューブ内に注ぎ、ボルテックスミキサで1秒間撹拌した。このマイクロチューブ内に上記試料750μLを添加し、再びボルテックスミキサで60秒間撹拌し、混合液を得た。同様に、陰性対照として、ヒト甲状腺刺激ホルモンが存在しない混合液も用意した。
上記混合液を動的光散乱方式粒度分布測定装置(DLS)[Malvarn社製のZETA SIZER Nano-ZS]内に設置し、37度の凝集条件下で35分間に亘って粒子径の測定を行った。同様に、陰性対照となる混合液についても粒子径の測定を行った。その結果を図2に示す。装置の条件は下記の通りである。
装置の条件:Refractive index=1.45、Absorption=0.010
[第1の結合物の調製]
まず、検出対象としてのヒト甲状腺刺激ホルモン(TSH)に対する第1の親和性物質としての抗体(クローン:195マウス、マウスIgG、Leinco Technology,Inc.製)を、従来周知のsulfo-NHS-Biotin法(旭テクノグラス社)によりビオチン化し、ビオチン標識抗TSHベータ抗体を調製した。
一方、ストレプトアビジンが結合された微粒子状の磁性物質であるマグナビート株式会社製のTherma-Max LSA Streptavidin(0.4質量%)250μLを1.5mLマイクロチューブにとり、このマイクロチューブを42℃に加熱することで、Therma-Max LSA Streptavidinを凝集させ、磁石で回収した後、上清を除去した。ここにTBSバッファー(20mM Tris-HCl、150mM NaCl、pH7.5)250μLを加え、冷却することで凝集物を分散させた。この分散液に、PBSバッファー(0.01M リン酸バッファー、0.0027M 塩化カリウム、0.137M 塩化ナトリウム、pH7.4)に溶解したビオチン標識抗TSHβ抗体50μL(0.75mg/mL)を加え、室温で15分間転倒混和した。マイクロチューブを42℃に加熱してTherma-Max LSA Streptavidinを凝集させ、磁石で回収した後、上清部分を除去し、余分なビオチン標識抗TSHベータ抗体を分離した(B/F分離)。ここにTBSバッファー250μLを加え、冷却することで凝集物を分散させた。続いて、過剰量のビオチンを添加して、ストレプトアビジンのビオチン結合部位を被覆した後、余分なビオチンを分離した(B/F分離)。さらに0.5%(w/v)BSA(シグマ社製)、0.5%(w/v)Tween(登録商標)20、10mM EDTAを含有させたPBSバッファー(pH7.4)溶液に分散させることで、第1の結合物を調製した。
第2の結合物の調製は、実施例1における第2の結合物の調製方法と同様である。
ヒト甲状腺刺激ホルモン(TSH;Aspen Bio Pharma,Inc.製、活性8.5IU/mg、WHO80/558)をPBSバッファー(pH7.4)に30μg/mLとなるように溶解した。この溶液をビトロスTSHキャリブレータ1(TSH:0mIU/L、オーソ・クリニカル・ダイアグノスティックス社製)で1ng/mL、となるよう希釈したものを試料とした。
第1の結合物150μL及び第2の結合物120μLをマイクロチューブ内に注ぎ、ボルテックスミキサで1秒間撹拌した。このマイクロチューブ内に上記試料750μLを添加し、再びボルテックスミキサで60秒間撹拌し、混合液を得た。同様に、陰性対照として、ヒト甲状腺刺激ホルモンが存在しない混合液も用意した。
汎用されている分光光度計用セミミクロセルの光路外に、寸法5mm×9mm×2mmのネオジム永久磁石(西興産業社製)を取り付けた。このセルを、セル温度制御機が設けられた可視紫外分光光度計「UV-3101PC」(島津製作所製)内に設置し、37℃のもと10分間以上保持した。
図2の結果から、粒子径に基づき定量を行う実施例では、初期段階(例えば、測定時間10分以内)においても、濁度(吸光度)に基づき定量を行う比較例に比べ、高い検出感度で定量が可能であることが確認された。また、粒子径に基づき定量を行う実施例では、比較例のように、磁石を設置する(固液分離をする)必要もなく、検出対象を高感度で検出できることが確認された。
Claims (7)
- 検体中の検出対象を定量する方法であって、
刺激応答性物質及び前記検出対象に対する第1の親和性物質を担持する担体粒子と、前記検体とを混合し、混合物を調製する混合工程と、
前記混合物を前記刺激応答性物質の凝集条件下におき、前記混合物中の懸濁物の粒子径を測定する測定工程と、
前記粒子径に基づき、前記検出対象の量を決定する決定工程と、を有する方法。 - 懸濁物に含まれる担体粒子の凝集物を固液分離する工程を、前記決定工程の前に含まない請求項1記載の方法。
- 前記担体粒子は非磁性物質からなる請求項1又は2記載の方法。
- 前記測定は、動的光散乱法を用いて行われる請求項1から3いずれか記載の方法。
- 前記担体粒子は、平均屈折率1.3以上を有する請求項4記載の方法。
- 前記測定は、陰性対照の濁度が前記凝集条件下においた後に最大値になるのに要する時間より前に行う請求項1から5いずれか記載の方法。
- 前記混合工程において、前記担体粒子に加え、親水性物質と前記検出対象に対する第2の親和性物質との結合物をさらに混合する請求項1から6いずれか記載の方法。
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Citations (6)
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JPH11337551A (ja) * | 1998-05-22 | 1999-12-10 | Sekisui Chem Co Ltd | 非特異反応抑制剤、免疫測定試薬及び免疫測定方法 |
JP2003121447A (ja) * | 2001-08-06 | 2003-04-23 | Jsr Corp | 免疫凝集反応用粒子 |
WO2008001868A1 (en) * | 2006-06-30 | 2008-01-03 | Chisso Corporation | Kit for detection/quantification of analyte, and method for detection/quantification of analyte |
WO2010137532A1 (ja) * | 2009-05-29 | 2010-12-02 | チッソ株式会社 | 検出対象の検出方法及び定量方法 |
WO2013118844A1 (ja) * | 2012-02-07 | 2013-08-15 | オーソ・クリニカル・ダイアグノスティックス株式会社 | 検出対象の検出及び定量のための方法及びキット |
WO2015050149A1 (ja) * | 2013-10-02 | 2015-04-09 | 古河電気工業株式会社 | 蛍光標識粒子 |
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JPH11337551A (ja) * | 1998-05-22 | 1999-12-10 | Sekisui Chem Co Ltd | 非特異反応抑制剤、免疫測定試薬及び免疫測定方法 |
JP2003121447A (ja) * | 2001-08-06 | 2003-04-23 | Jsr Corp | 免疫凝集反応用粒子 |
WO2008001868A1 (en) * | 2006-06-30 | 2008-01-03 | Chisso Corporation | Kit for detection/quantification of analyte, and method for detection/quantification of analyte |
WO2010137532A1 (ja) * | 2009-05-29 | 2010-12-02 | チッソ株式会社 | 検出対象の検出方法及び定量方法 |
WO2013118844A1 (ja) * | 2012-02-07 | 2013-08-15 | オーソ・クリニカル・ダイアグノスティックス株式会社 | 検出対象の検出及び定量のための方法及びキット |
WO2015050149A1 (ja) * | 2013-10-02 | 2015-04-09 | 古河電気工業株式会社 | 蛍光標識粒子 |
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