CA2026515C - Immunoassay using magnetic particle - Google Patents
Immunoassay using magnetic particle Download PDFInfo
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- CA2026515C CA2026515C CA002026515A CA2026515A CA2026515C CA 2026515 C CA2026515 C CA 2026515C CA 002026515 A CA002026515 A CA 002026515A CA 2026515 A CA2026515 A CA 2026515A CA 2026515 C CA2026515 C CA 2026515C
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- antibody
- antigen
- enzyme
- immunoassay method
- core
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
- B03C1/005—Pretreatment specially adapted for magnetic separation
- B03C1/01—Pretreatment specially adapted for magnetic separation by addition of magnetic adjuvants
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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
- G01N33/5434—Magnetic particles using magnetic particle immunoreagent carriers which constitute new materials per se
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2446/00—Magnetic particle immunoreagent carriers
- G01N2446/10—Magnetic particle immunoreagent carriers the magnetic material being used to coat a pre-existing polymer particle but not being present in the particle core
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2446/00—Magnetic particle immunoreagent carriers
- G01N2446/80—Magnetic particle immunoreagent carriers characterised by the agent used to coat the magnetic particles, e.g. lipids
- G01N2446/86—Magnetic particle immunoreagent carriers characterised by the agent used to coat the magnetic particles, e.g. lipids the coating being pre-functionalised for attaching immunoreagents, e.g. aminodextran
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2446/00—Magnetic particle immunoreagent carriers
- G01N2446/80—Magnetic particle immunoreagent carriers characterised by the agent used to coat the magnetic particles, e.g. lipids
- G01N2446/90—Magnetic particle immunoreagent carriers characterised by the agent used to coat the magnetic particles, e.g. lipids characterised by small molecule linker used to couple immunoreagents to magnetic particles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S435/00—Chemistry: molecular biology and microbiology
- Y10S435/968—High energy substrates, e.g. fluorescent, chemiluminescent, radioactive
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S436/00—Chemistry: analytical and immunological testing
- Y10S436/806—Electrical property or magnetic property
Abstract
An immunoassay method using magnetic particles comprising a core and a coating layer on the surface thereof.
The core comprises an organic polymer and the coating layer comprises an iron oxide type ferrite coating layer. An antigen or an antibody is bound onto the surface of the coating layer, and the particle has a particle size of 0.2 to 3 µm.
The core comprises an organic polymer and the coating layer comprises an iron oxide type ferrite coating layer. An antigen or an antibody is bound onto the surface of the coating layer, and the particle has a particle size of 0.2 to 3 µm.
Description
~0~~5 ~
IMMUNOASSAY USING MAGNETIC PARTICLE
This invention relates to an immunoassay using magnetic particles, more specifically to an enzyme immunoassay using magnetic particles in which a core comprises an organic polymer and a surface comprises a ferrite coating layer composed of iron oxide and an antigen or antibody is bound thereto, and a particle size of which is 0.2 to 3 um.
In an immunoassay, particularly in an enzyme immunoassay, it is advantageous to effect immuno reaction with high sensitivity since it employs in a solid phase latex particles with smaller particle sizes in place of beads having larger particle sizes. However, when particles having smaller particle sizes are employed, for effecting bound/free (B/F) separation, a centrifugal separator should be used or filtration by using a filter should be done: As a method for effecting B/F separation effectively and simply, there has been proposed a method in which magnetic particles having small particle size are employed. In such methods, there have been known an immunoassay using particles having 1.0 to 10.0 um wherein a silane is coated on magnetite as a core (see Japanese Provisional Patent Publications No. 141670/1980 and No. 122997/1975), and an immunoassay using particles having 0.1 to l.5 um wherein a silane is coated on a magnetic metal oxide as core (see __.2x26515 Japanese Provisional Patent Publication No. 1564/1985). In either of the magnetic particles, the core comprises a magnetic metal, and a silane is used for coating thereon.
Particles comprising these magnetic metals as a core have problems in that they do not have sufficient uniformity of particle size, and they also are poor in preservation stability for a long period of time since iron is dissolved out. Thus, in immunoassay methods using these particles, reproducibility of the measured results is poor, and the reagent used for the measurement could not be preserved for a long period of time.
The present inventors have studied intensively to overcome these problems, and as a result, they have found that when magnetic particles which comprise a core composed of an-organic polymer and a surface composed of an iron oxide type ferrite coating layer, with a particle size of 0.2 to 3 um, and an antigen or an antibody bound on the particles are employed for an immunoassay method, measured results excellent in reproducibility can be obtained. This also arises from the fact that the magnetic particles are stable for a long period of time so that preservation for a long period of time is possible.
IMMUNOASSAY USING MAGNETIC PARTICLE
This invention relates to an immunoassay using magnetic particles, more specifically to an enzyme immunoassay using magnetic particles in which a core comprises an organic polymer and a surface comprises a ferrite coating layer composed of iron oxide and an antigen or antibody is bound thereto, and a particle size of which is 0.2 to 3 um.
In an immunoassay, particularly in an enzyme immunoassay, it is advantageous to effect immuno reaction with high sensitivity since it employs in a solid phase latex particles with smaller particle sizes in place of beads having larger particle sizes. However, when particles having smaller particle sizes are employed, for effecting bound/free (B/F) separation, a centrifugal separator should be used or filtration by using a filter should be done: As a method for effecting B/F separation effectively and simply, there has been proposed a method in which magnetic particles having small particle size are employed. In such methods, there have been known an immunoassay using particles having 1.0 to 10.0 um wherein a silane is coated on magnetite as a core (see Japanese Provisional Patent Publications No. 141670/1980 and No. 122997/1975), and an immunoassay using particles having 0.1 to l.5 um wherein a silane is coated on a magnetic metal oxide as core (see __.2x26515 Japanese Provisional Patent Publication No. 1564/1985). In either of the magnetic particles, the core comprises a magnetic metal, and a silane is used for coating thereon.
Particles comprising these magnetic metals as a core have problems in that they do not have sufficient uniformity of particle size, and they also are poor in preservation stability for a long period of time since iron is dissolved out. Thus, in immunoassay methods using these particles, reproducibility of the measured results is poor, and the reagent used for the measurement could not be preserved for a long period of time.
The present inventors have studied intensively to overcome these problems, and as a result, they have found that when magnetic particles which comprise a core composed of an-organic polymer and a surface composed of an iron oxide type ferrite coating layer, with a particle size of 0.2 to 3 um, and an antigen or an antibody bound on the particles are employed for an immunoassay method, measured results excellent in reproducibility can be obtained. This also arises from the fact that the magnetic particles are stable for a long period of time so that preservation for a long period of time is possible.
'~~' In the following, the present invention will be described in more detail, with reference to the accompanying drawings, in which:
Fig. 1 is a graph showing results of CEA assay using ferrite coating particles and particles manufactured by Advanced Magnetics Inc., and Fig. 2 is a graph showing the magnetic particles separating rate of ferrite particles.
Preparation of magnetic particles The magnetic particles to be used in the present invention can be prepared by using an organic polymer as a core and subjecting them to an iron oxide type ferrite coating, and then binding an antigen or an antibody to the resulting magnetic particles. The organic polymer comprises at least one polymer; a polystyrene or at least one of an acrylate and a methacrylate (hereinafter (meth)acrylates).
Examples of (meth)acrylates may include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, glycerol monomethacrylate, 2-acrylamido-2-methylpropane sulfonic acid, 2-sulfoethyl methacrylate, acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate, acid phosphoxypropyl methacrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, -.~ 2f~2651 i-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl methacrylate, cyclohexyl methacrylate, (meth)acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide, glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.
As the method of polymerization using these monomers, emulsion polymerization and multistage emulsion polymerization can be used. As the emulsion polymerization method, there has been known the method in which polymeri-zation is carried out by charging the whole monomer composition at one time, the monomer addition method in which a part of the monomers and components other than the monomers are prepolymerized and then polymerization is further carried out by continuously adding the remaining monomers to the prepolymer, and the emulsion addition method in which polymer compositions are previously emulsified to effect prepolymerization of a part thereof, and then remaining emulsions are continuously added to complete the polymerization. Also, the multistage polymerization method in which seed latex particles are stepwisely grown without generating new latex particles has been known.
For effecting these polymerization reactions, an organic peroxide type initiator such as benzoyl.peroxide, lauroyl peroxide, cumen hydroperoxide, di-t-butylperoxide and acetyl peroxide, and a nitrile type initiator such as oc,oc'-azobisisobutyronitrile have been known as radical polymerization initiators. Also, a compound such as potassium persulfate, ammonium persulfate and hydrogen peroxide may be used. Further, a redox type polymerization catalyst may be employed.
As an emulsifier to be used for the emulsion polymerization, there may be mentioned an ionic active agent such as an anionic active agent, cationic active agent, amphoteric active agent and nonionic active agent.
Next, ferrite coating is carried out to the core of organic polymer obtained by the method mentioned above, to form ferrite coated particles.
The ferrite coating is carried out in an aqueous solution containing core particles. The aqueous solution contains ferrous ions which are essential for forming ferrite coat-ings. The ferrous ions are supplied in the aqueous solution in the form of a ferrous salt such as hydrochloride, sulfate and acetate. When the aqueous solution contains only ferrous ions as the metal ion, the coating can be obtained as a spinel ferrite which contains only iron as a metal element, i.e. coatings of magnetite Fes09. Also, in the aqueous solution, other transition metal ions (M°+) may be present in addition to the ferrous ion. Such other metal ~~.:
ion species may include zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium and indium. When the Mn+ is cobalt, coatings of cobalt ferrite (CoXFe3_XOq) and nickel ferrite (NiXFe3_x04) can be obtained, and when the M°+ is plural kinds of species, mixed crystal ferrite can be obtained. These metal ion species other than ferrous ion can be formulated in the aqueous solution in the form of salts.
l0 In the present invention, formation of ferrite coatings is started by adding an oxidizing agent solution to a deoxygenated aqueous solution containing ferrous ions and core particles. Examples of the oxidizing agent may include nitrites, nitrates, hydrogen peroxide; organic peroxides, perchlorates and oxygen-dissolved water: More preferably, an aqueous solution of the oxidizing agent is added dropwise to the solution with a constant ratio as in the titration method of analytical chemistry. According to the dropwise 20 addition with a constant ratio, a thickness of the ferrite coatings can be easily adjusted.
A pH of the aqueous solution can be optionally selected depending on the kinds of anions and metal ions present in an aqueous solution and can be controlled, but preferably is in the range of 6 to 11, more preferably 7 to 11. For stabilizing the pH, a buffer such as ammonium acetate or a salt having a buffering effect may be added.
A temperature to carry out the reaction of the present invention may be in the range of the boiling point of the aqueous solution or lower, but the reaction is preferably carried out in the range of 60° C to 90° C. Also, the reaction is carried out under a substantially deoxidized atmosphere. Under conditions exhibiting larger amounts of oxygen, the oxidization reaction proceeds unnecessarily.
More specifically, it is preferred to carry out the reaction under nitrogen atmosphere. Also, oxygen is removed from the aqueous solution to provide a deoxygenated aqueous solution, similarly.
A suitable method in the present invention is firstly to suspend the particulate materials in the deoxygenated water.
At this time, wetting of the particulate materials to water may be improved by, if necessary, adding an additive such as a surfactant. Then, if necessary, a pH buffer, etc. may be added to adjust a pH, and then ferrous ions are added thereto in the form of a salt. Also, other metal ions may be added thereto simultaneously with the ferrous ions depending on necessity. After completion of addition of all components, the reaction is initiated by adding an oxidizing agent solution to the mixture solution with the titration s zoz~~ ~
method as mentioned above. This procedure is particularly preferred since the thickness of the ferrite coatings can be controlled by the concentration of the metal ion species or the oxidizing agent. The resulting particulate materials provided with ferrite coatings are separated by filtration and dried to obtain the desired products.
Preparation of particles treated by polymer compound The magnetic particles to be used in the present invention may be used after treating with a polymer compound. As the polymer compound, there may lae used, for example, a silane, nylon (trade name) or a polystyrene. As the method of silane treatment, for example, the acidic aqueous silylation method may be used. It can be accomplished by, firstly mixing ferrite coated particles and silane monomer in an acidic solution, and then treating the mixture at room temperature to 95° C under heating. As the silane monomer to be used, there may be used, for example, an organosilane such as p-aminophenyltrimethoxysilane, 3-aminopropyl-trimethoxysilane, N-2-aminoethyl-3-aminopropyl-trimethoxysilane, triamino-functional silane (HZNCH2CH2-NHCH2CH2NHCHZCHZCH2-Si- (OCH3) 3) , n-dodecyltriethoxysilane and n-hexyltrimethoxysilane. Further, in order to convert an end amino group of the silane into a carboxylic group, an acid anhydride can be reacted with silane-treated particles at room temperature. Also, for treating polyamide; ferrite coated particles are suspended in a l~ aqueous sodium carbonate solution, an appropriate amount of hexamethylenediamine is dissolved therein, and 5-fold amounts of a hexane-chloroform mixed solution (3 . 1) containing 8~ Tween 80 (trade name, produced by Kao Corp.) is mixed with the solution, and it then is subjected to ultrasonic treatment to form an emulsion. Then, by adding dropwise the same hexane-chloroform mixed solution as mentioned above containing sebacoyl dichloride with an equimolar amount of hexamethylenediamine, the desired particles can be obtained. Also, in the case of a polystyrene, it can be treated by employing the method known in the art. Further, magnetic particles can be directly coated by spraying or dipping in a polymer resin solution such as nylon (trade name) and a polystyrene.
The present invention relates to magnetic particles obtained by binding an antigen or an antibody to the ferrite coated particles or further polymer compound-treated particles obtained by the above method. As the antibody to be used, there may be mentioned, for example, a chemical such as theophylline, phenytoin and valproic acid; a low molecular hormone such as thyroxine, estrogen and estradiol; a cancer marker such as CEA and AFP; a virus antigen such as HIV, ATLA and HBV; a high molecular hormone such as TSH and "'Sf - ,.
insulin; a cytocain such as IL-1, IL-2 and IL-6; various kinds of gloss factor such as EGF and PDGF; and further an antibody to a suitable DNA, RNA, etc. of the above viruses.
Also, as the antigen to be used, there may be mentioned a virus such as HIV, ATLA and HBV; DNA of the above viruses; a high molecular hormone such as insulin and TSH.
As the bonding method, the physical absorption method or the chemical bonding method may be employed. The physical absorption method is carried out in an appropriate buffer solution by reacting the above particles and an antigen or an antibody. As the buffer solution to be used in this reaction, there may be mentioned a phosphate buffer solution, a tris-hydrochloride buffer solution and a carbonate buffer solution. The reaction can proceed easily by mixing both of the components at room temperature to obtain the desired product. Also, as the chemical bonding method, the carbodiimide method in the so-called peptide bonding method can be employed: Bonding can be carried out, for example, by adding an equiamount of a water-soluble carbodiimide to a dispersion of 0.1 to 5 $ of silylated particles under acidic conditions (pH 4 to 6), reacting at room temperature for 10 minutes to one hour, removing a supernatant, and then adding 0.01 to 10.0 mg/ml, preferably 0.1 to 5 mg/ml of an antibody or an antigen solution. The buffer to be used at this time is preferably a phosphate i.
2~~~5~
buffer. Also, as the other chemical bonding method, the method in which the reaction is carried out in the presence of a divalent cross-linking reagent such as glutaraldehyde and cyanuric chloride may be employed (see "Peptide Synthetic Method", published by Maruzene K.K. (published in 1975) and "Enzyme Immunoassay Method", published by Kyoritsu Shuppan K.K., "Protein, Nucleic acid, Enzyme", special issue No. 31 (1987)).
The magnetic particles produced as mentioned above had a constant particle size. These particles had not changed even when they were preserved in an appropriate protein solution such as BSA and globulin for one year.
The magnetic particles according to the present invention have a particle size of 0.2 um or more to 3 um or less. If the particle size becomes in excess of 3 um, floating time is short when they are used in immurio reaction so that sufficient reaction cannot be carried out. Also, if it is less than 0.2 um, magnetic separating efficiency after immunoassay becomes difficult.
Immunoassay method As the immunoassay method in accordance with the present invention, the radioactive immunoassay method and the enzyme immunoassay method can be used. These assay methods are the immunoassay methods using a label, and an antigen or an antibody to be assayed can be assayed by the sandwich method or the competition method.
The enzyme immunoassay method according to the present invention is, for example, carried out by reacting an antibody-bound magnetic particle and an enzyme-labelled antibody for 10 minutes to 3 hours. A reaction temperature when practicing the reaction is 4° C to 40° C, and preferably 25° G to 38° C. After washing an unreacted enzyme-labeled antibody, an amount of a ligand of specimen can be determined by measuring an amount of an antigen-bound enzyme bound to a solid phase, by adding an enzyme substrate and measuring an activity thereof. An enzyme to be used in the method of the present invention may include peroxidase, alkaline phosphatase, ~3-galactosidase and glucose-oxidase. At this time, it is needless to say that a substrate to be used should be that which is suitable for an enzyme to be used.
As such substrates, there may be used, for example, ABTS, luminol-H202 (for peroxidase), 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt (AMPPD), p-nitrophenylphosphate and methylumbelliferyl phosphate (for alkaline phosphatase), p-nitrophenyl-(3-0-glactose and methyl-umbelliferyl-(3-o-galactose (for (3-galactosidase). The measurement can be carried out by reacting at room temperature to 40° C for 1 minute to 18 hours; and then measuring an amount of color, fluorescence or luminescence generated. As the other method, the so-called rate method in which it is carried out at a temperature range of 4° C to 40° C under heating may be employed.
Also, the radioimmunoassay method in the immunoassay method is carried out by labelling a radioisotope such as lzsI in place of the above enzyme label. Operations are quite the same with the above enzyme immunoassay method, except for measuring radioactivity.
Also, radiolabelling of an antigen or an antibody can be readily accomplished by the already available Bolton-Hunter reagent. It can be prepared by, for example, adding the Bolton-Hunter reagent to an antigen or an antibody solution dissolved in a 0.1 M sodium hydrogen carbonate aqueous solution, and after l to 2 hours, removing unreacted Bolton-Hunter reagent by using a desalting column of G-25, etc. In addition, radiolabelling of 1251 can be easily carried out by employing the chloramine T method or the iododine method.
For effecting the immuno reaction, a sample is added to the magnetic particles of the present invention, and reacted at 4° C to 40° C, preferably 20° C to 38°
C for 1 to 18 hours. Thereafter, washing is carried out by a ~~ ~'4' physiological salt solution or distilled water, radiolabelled antibody is added to magnetic particles and reacted at 4° C to 40° C, preferably 20° C to 38°
C for 1 to 18 hours, washed with a physiological salt solution or distilled water and then determining its radioactivity. A
scintillation counter can be used for the measurement.
Also, the assay method of the present invention may be carried out by the chemiluminescent assay method in which isoluminol or acridine ester is labelled, or the fluorescent immunoassay method in which fluoresceine or rhodamine is labelled. During the procedures, labelling of a labelling substance can be easily carried out by employing the active ester method or the isocyanate method (see "Enzyme immunoassay method" (published by Igaku Shoin, 1987)).
Similarly, measurement of the antibody can be carried out by using the magnetic particles of the present invention, mixing these particles with a sample to react them at a room temperature to 37° C for one minute to 18 hours, washing with a physiological salt solution or distilled water, and then adding labelled-anti-human immunoglobulin antibody to react at a room temperature to 37° C for 1 minute to 18 hours, washing and measuring the activity of the labelled substance.
:4~
202b515 The present invention is an enzyme immunoassay method using particles comprising magnetic particles composed of an organic polymer as a core and a ferrite layer deposited on the surface thereof, and an antigen or antibody bound on the surface of the ferrite layer. These particles may be used as a solid phase of an immunoassay method.
L~VTMDT L~C'~
l In the following, the present invention will be explained by referring to Examples in more detail.
Example 1 Preparation of organic polymer particles In an apparatus for polymerization reaction having a stirrer, a thermometer, a monomer-dropping funnel, a reflux condenser, 20 a heating device and a nitrogen gas inlet tube was charged 230 parts of deionized water, followed by adding 1 part of a mixed monomer (A) composed of styrene, 2-ethylhexyl acrylate and ethyleneglycol dimethacrylate (80/10/10) and 10 parts of a 10 ~ aqueous ammonium persulfate solution, and then adding dropwise 99 parts of the above mixed monomer (A) over 3 hours to obtain a latex. When the particles were observed by 202b5Z5 electron microscope, they were substantially monodispersed and a particle size of 0.3 um.
Preparation of ferrite coated particles In a magnetic particle preparing apparatus having a stirrer, a thermometer, an oxidizing agent dropping funnel, a heating device and a nitrogen gas inlet tube was charged 100 parts of the above emulsion (30 ~ solid content) and degassed oxygen in the core emulsion by introducing N2 gas.
Then, previously prepared 100 parts (solid content: 40 parts) of ferrous chloride solution and 150 parts (solid content: 75 parts) of ammonium acetate were thrown in the apparatus and the mixture was sufficiently stirred at 70° C under heating.
Thereafter, while continuing stirring, a pH of the mixture was adjusted to 7.2 with aqueous ammonia.
To the solution was added dropwise 150 parts (solid content:
15 parts) of a sodium nitrite solution over about one hour.
During dropwise addition and reaction, a temperature of the mixture was maintained to 70° C and a pH in the range of 7.0 to 7.2 while continuing introduction of nitrogen gas and stirring to form ferrite coatings on the surfaces of said particles. After about 20 minutes, the solution was cooled, and repeated to filtering and washing with deionized water, °'~fi.
z 2~~515 and then taken out particles to obtain ferrite coated particles.
Example 2 Preparation of anti-TSH mouse IgG-bound magnetic particles To 4 ml of a 5 ~ ferrite coated particles-dispersed aqueous dispersion (20 mM phosphate buffer, pH 3.5) prepared in Example 1 was added 1 ml of anti-TSH mouse IgG (5 mg/ml), and the mixture was stirred by an end-over-end mixer at room temperature overnight. After separating this particle dispersion with a magnet having 3000 gauss at the surface thereof to a supernatant and particles, the supernatant was removed, and the particles were washed five times with a 2 BSA solution (0.1 M Tris-hydrochloric acid, 1 mM magnesium chloride and 0.1 mM zinc chloride, pH: 7.5). Then, the particles were dispersed in 5 ml of the similar BSA solution to prepare magnetic particles.
. 17 g':.y .
~r Example 3 Preparation of anti-CEA mouse IgG-bound magnetic particles To 4 ml of a 5 ~ ferrite coated particles-dispersed aqueous dispersion (20 mM phosphate buffer, pH 3.5) prepared in Example l was added 1 ml of anti-CEA mouse IgG (5 mg/ml), and the mixture was stirred by an end-over-end mixer at room temperature overnight. After separating this particle . dispersion with a magnet having 3000 gauss at the surface thereof to a supernatant and particles, the supernatant was removed, and the particles were washed five times with a 2 ~
BSA solution (0.1 M Tris-hydrochloric acid, 1 mM magnesium chloride and 0.1 mM zinc chloride, pH: 7.5). Then, the particles were dispersed in 5 ml of the similar BSA solution to prepare magnetic particles.
Example 4 Preparation of carboxylated-ferrite particles Carboxylated ferrite particles can be obtained by adding 50 ml of 3-aminopropyltriethoxysilane to 5 g of ferrite particles (polystyrene having an average particle size of the core of 0.3 um) of Example 1 which had been previously washed 5 times for each 60 seconds with distilled water by using an B
ultrasonic washing machine (Batt type, manufactured by Nippon Seiki Seisakusho K.K.1, further adding 30 ml of glacial acetic acid to react at room temperature for 3 hours, followed by washing and reacting with glutaric acid anhydride. Glacial acetic acid was added dropwise under ice-cooling and stirring, and washing was carried out each three times with distilled water, methanol and distilled water, and further five times with each 300 ml of 0.1 M sodium hydrogen carbonate solution. The reaction with glutaric acid was carried out by adding 2.85 g of glutaric acid anhydride to 100 ml-of 5 ~ by weight (0.1 M sodium hydrogen carbonate solution) particles and reacting for l0 minutes. After completion of the reaction, the mixture was washed three times with each 300 ml of 0.1 M sodium hydrogen carbonate solution, and further five times with distilled water. This was used'as carboxylated ferrite particles.
Example 5 Preparation of anti-TSH bound carboxylated-ferrite In 5 ml of 2O mM phosphate buffer (pH 4.5) was dispersed 50 mg of carboxylated ferrite particles prepared in Example 4, followed by adding 50 mg of water-soluble carbodiimide.
After reacting at room temperature for 20 minutes, the supernatant was removed, and 5 ml of anti-TSH mouse IgG
B
202~~i~
solution (1 mg/ml, 0.02 M phosphate buffer solution, pH:
4.5), and the mixture was stirred by an end-over-end mixer.
After 2 hours, these particles were washed five times with 2 ~ BSA solution (0.1 M Tris-HCl, 1 mM MgCl2, pH: 7.5) and dispersed in the similar BSA solution to obtain anti-TSH-mouse IgG sensitized carboxylated-ferrite particles.
Example 6 TSH assay using anti-TSH sensitized ferrite particles To a sample containing 15 ul of TSH (0, 10 uU/ml) was mixed ul of alkali phosphatase conjugate (conjugate concentration: 0.5 ug/ml, 0.1 M Tris-hydrochloric acid, 2 BSA, 1 mM MgCl2, 0.1 mM ZnCl2, pH: 7.5) to which anti-TSH Fab' is bound, and then 500 ul (0.02 ~ solution) of ferrite particles prepared in Example 2 on which anti-TSH mouse IgG
was coated was mixed to the above mixture, and the resulting mixture was allowed to stand at room temperature for 20 20 minutes. A tube containing the above mixture was contacted with a magnet having a surface magnetic field of 3000 gauss to attract ferrite particles and the supernatant was removed by decantation. Thereafter, 1 ml of 0.04 ~ physiological salt solution was added to the particles and the mixture was stirred. The tube was again contacted with the above mentioned magnet to separate the particles and a supernatant, 2~~65) and the supernatant was removed by decantation. These operations were repeated three times. To the tube containing these particles was added 200 ul of a substrate solution (0.1 M Tris-hydrochloric acid, 1 uM MgClz, 0.1 mM ZnCl2, pH: 9.8) containing 100 ug/ml of 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt (AMPPD) and the mixture was reacted at room temperature. After carrying out the reaction for 17 minutes, the sample was measured by a luminometer (manufactured by Belthold Co.).
In Table l, an S/N ratio of integrated value for 5 minutes was shown. For comparison, the results wherein ferrite particles produced by Advanced Magnetics Inc. [magnetic carrier for Affinity Chromatography (carboxyl group terminated)] were used are also shown.
Table 1 S/N ratio Magnification Ferrite coated particles 47.4 6.2 Particles produced by 7.6 1 Advanced Magnetics Co.
_ k~.~., , Example 7 202~51.~
TSH assay using carboxylated particles To a sample containing 15 ul of TSH (0, 10 uU/ml) was mixed 20 ul of alkali phosphatase conjugate (conjugate concentration: 0.5 ug/ml, 0.1 M Tris-hydrochloric acid, 2 BSA, 1 mM MgCl2, 0.1 mM ZnCl2, pH: 7.5) to which anti-TSH
Fab' is bound, and then 500 ul (0.02 % solution) of carboxylated ferrite particles prepared in Example 5 on which anti-TSH mouse IgG was coated was mixed to the above mixture, and the resulting mixture was allowed to stand at room temperature for 20 minutes. A tube containing the above mixture was contacted with a magnet having a surface magnetic field of 3000 gauss to attract ferrite particles and the supernatant was removed by decantation. Thereafter, 1 ml of 0.04 % physiological salt solution was added to the particles and the mixture was stirred. The tube was again contacted with the above mentioned magnet to separate the particles and a supernatant, and the supernatant was removed by decantation. These operations were repeated three times. To the tube containing these particles was added 200 ~Zl of a substrate solution (0.1 M Tris-hydrochloric acid, 1 ~.zM MgCl2, 0.1 mM ZnCl2, pH: 9.8) containing 100 ug/ml of AMPPD and the mixture was reacted at room temperature. After carrying out r s '~ _., .....>~
the reaction for 17 minutes, the sample was measured by a luminometer (manufactured by Belthold Co.).
In Table 2, an S/N ratio of integrated value for 5 minutes was shown. For comparison, the results wherein ferrite particles produced by Advanced Magnetics Inc. [magnetic carrier for Affinity Chromatography (carboxyl group terminated)] were used are also shown.
Table 2 S/N ratio Magnification Ferrite coated particles 78.2 10.0 Particles produced by 7.6 1 Advanced Magnetics Co.
Example 8 CEA assay using anti-CEA sensitized ferrite particles To a sample containing 15 ul of CEA (0, 25,50 ng/ml) was mixed 20 ul of alkali phosphatase conjugate (conjugate concentration: 0.2 ug/ml, 0.1 M Tris-hydrochloric acid, 2 ~ BSA, 1 mM MgCl2, 0.1 mM ZnCl2, pH: 7.5) to which anti-CEA Fab' is bound, and then 500 ul (0.02 ~ solution) of ferrite particles prepared in Example 3'on which anti-CEA
\.... 'b'~~~~...;.
r ~~~~~1 mouse IgG was coated was mixed to the above mixture, and the resulting mixture was allowed to stand at room temperature for 20 minutes. A tube containing the above mixture was contacted with a magnet having a surface magnetic field of 3000 gauss to attract ferrite particles and the supernatant was removed by decantation.
Thereafter, 1 ml of 0.04 ~ physiological salt solution was added to the particles and the mixture was stirred. The tube was again contacted with the above mentioned magnet to separate the particles and a supernatant, and the supernatant was removed by decantation. These operations were repeated three times. To the tube containing these particles was added 200 pl of a substrate solution (0.1 M
Tris-hydrochloric acid, 1 uM MgCl2, 0.1 mM ZnCl2, pH: 9.8) containing 100 ~Zg/ml of AMPPD and the mixture was reacted at room temperature. After carrying out the reaction for 17 minutes, the sample was measured by a luminometer (manufactured by Belthold Co.).
In Fig. 1, an S/N ratio of integrated value for 5 minutes is shown. For comparison, the results wherein ferrite particles produced by Advanced Magnetics Inc. [magnetic carrier for Affinity Chromatography (carboxyl group terminated)] were used are also shown.
.. . _. _.._. 2 4 ., ~(~~~515 Example 9 Comparison of magnetic separating rate of ferrite particles In a tube was charged 500 ul of 0.02 ~ anti-TSH mouse IgG
bound ferrite particles (2 ~ BSA, 0.1 M Tris-HC1, 1 mM
MgCl2, pH: 9.8), and the tube was contacted with a magnet having a surface magnetic field of 3000 gauss.
After 0, 10, 20, 30, 40 and 60 seconds of the contact, a supernatant was separated and an absorption at a wavelength of 660 nm was measured. The results of separating rate are shown in Fig. 2.
Example 10 Investigation of floating property of particles Anti-TSH mouse IgG bound ferrite particles (0.02 ~) were charged in a 1000 ul tube and allowed to stand at room temperature.
Supernatants at 0 minute and after 30 minutes were sampled and absorption at a wavelength of 660 nm was measured.
~_ _ 2 5 ~ r~
~,A>?:.~.. a -.:~~~5 i Its relative turbidity is shown in Table 3.
Table 3 Relative turbidit Ferrite coated particles 80 ~
Particles manufactured by 72 Advanced Magnetics Inc.
(The relative turbidity means a turbidity after "30 minutes"
when a turbidity at "0 minute after allowed to stand" as "100 ~" . ) The present invention relates to an enzyme immunoassay method using particles composed of a magnetic particle comprising an organic polymer as a core and ferrite coatings coated on the surface thereof, and an antigen or antibody bound to the surface of the magnetic particle. The particles according to the present invention have uniform particle size and are excellent in binding state of an antigen or antibody to the particles. Further, the particles according to the present invention have advantages that they are stable for a long period of time and thus can be preserved. An enzyme immunoassay method according to the present invention can be carried out by using the particles, rapidly and with high sensitivity.
Fig. 1 is a graph showing results of CEA assay using ferrite coating particles and particles manufactured by Advanced Magnetics Inc., and Fig. 2 is a graph showing the magnetic particles separating rate of ferrite particles.
Preparation of magnetic particles The magnetic particles to be used in the present invention can be prepared by using an organic polymer as a core and subjecting them to an iron oxide type ferrite coating, and then binding an antigen or an antibody to the resulting magnetic particles. The organic polymer comprises at least one polymer; a polystyrene or at least one of an acrylate and a methacrylate (hereinafter (meth)acrylates).
Examples of (meth)acrylates may include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 1-methyl-2-hydroxyethyl (meth)acrylate, glycerol monomethacrylate, 2-acrylamido-2-methylpropane sulfonic acid, 2-sulfoethyl methacrylate, acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate, acid phosphoxypropyl methacrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, -.~ 2f~2651 i-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl methacrylate, cyclohexyl methacrylate, (meth)acrylamide, N-methylol acrylamide, N-butoxymethyl acrylamide, glycidyl (meth)acrylate and methylglycidyl (meth)acrylate.
As the method of polymerization using these monomers, emulsion polymerization and multistage emulsion polymerization can be used. As the emulsion polymerization method, there has been known the method in which polymeri-zation is carried out by charging the whole monomer composition at one time, the monomer addition method in which a part of the monomers and components other than the monomers are prepolymerized and then polymerization is further carried out by continuously adding the remaining monomers to the prepolymer, and the emulsion addition method in which polymer compositions are previously emulsified to effect prepolymerization of a part thereof, and then remaining emulsions are continuously added to complete the polymerization. Also, the multistage polymerization method in which seed latex particles are stepwisely grown without generating new latex particles has been known.
For effecting these polymerization reactions, an organic peroxide type initiator such as benzoyl.peroxide, lauroyl peroxide, cumen hydroperoxide, di-t-butylperoxide and acetyl peroxide, and a nitrile type initiator such as oc,oc'-azobisisobutyronitrile have been known as radical polymerization initiators. Also, a compound such as potassium persulfate, ammonium persulfate and hydrogen peroxide may be used. Further, a redox type polymerization catalyst may be employed.
As an emulsifier to be used for the emulsion polymerization, there may be mentioned an ionic active agent such as an anionic active agent, cationic active agent, amphoteric active agent and nonionic active agent.
Next, ferrite coating is carried out to the core of organic polymer obtained by the method mentioned above, to form ferrite coated particles.
The ferrite coating is carried out in an aqueous solution containing core particles. The aqueous solution contains ferrous ions which are essential for forming ferrite coat-ings. The ferrous ions are supplied in the aqueous solution in the form of a ferrous salt such as hydrochloride, sulfate and acetate. When the aqueous solution contains only ferrous ions as the metal ion, the coating can be obtained as a spinel ferrite which contains only iron as a metal element, i.e. coatings of magnetite Fes09. Also, in the aqueous solution, other transition metal ions (M°+) may be present in addition to the ferrous ion. Such other metal ~~.:
ion species may include zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium and indium. When the Mn+ is cobalt, coatings of cobalt ferrite (CoXFe3_XOq) and nickel ferrite (NiXFe3_x04) can be obtained, and when the M°+ is plural kinds of species, mixed crystal ferrite can be obtained. These metal ion species other than ferrous ion can be formulated in the aqueous solution in the form of salts.
l0 In the present invention, formation of ferrite coatings is started by adding an oxidizing agent solution to a deoxygenated aqueous solution containing ferrous ions and core particles. Examples of the oxidizing agent may include nitrites, nitrates, hydrogen peroxide; organic peroxides, perchlorates and oxygen-dissolved water: More preferably, an aqueous solution of the oxidizing agent is added dropwise to the solution with a constant ratio as in the titration method of analytical chemistry. According to the dropwise 20 addition with a constant ratio, a thickness of the ferrite coatings can be easily adjusted.
A pH of the aqueous solution can be optionally selected depending on the kinds of anions and metal ions present in an aqueous solution and can be controlled, but preferably is in the range of 6 to 11, more preferably 7 to 11. For stabilizing the pH, a buffer such as ammonium acetate or a salt having a buffering effect may be added.
A temperature to carry out the reaction of the present invention may be in the range of the boiling point of the aqueous solution or lower, but the reaction is preferably carried out in the range of 60° C to 90° C. Also, the reaction is carried out under a substantially deoxidized atmosphere. Under conditions exhibiting larger amounts of oxygen, the oxidization reaction proceeds unnecessarily.
More specifically, it is preferred to carry out the reaction under nitrogen atmosphere. Also, oxygen is removed from the aqueous solution to provide a deoxygenated aqueous solution, similarly.
A suitable method in the present invention is firstly to suspend the particulate materials in the deoxygenated water.
At this time, wetting of the particulate materials to water may be improved by, if necessary, adding an additive such as a surfactant. Then, if necessary, a pH buffer, etc. may be added to adjust a pH, and then ferrous ions are added thereto in the form of a salt. Also, other metal ions may be added thereto simultaneously with the ferrous ions depending on necessity. After completion of addition of all components, the reaction is initiated by adding an oxidizing agent solution to the mixture solution with the titration s zoz~~ ~
method as mentioned above. This procedure is particularly preferred since the thickness of the ferrite coatings can be controlled by the concentration of the metal ion species or the oxidizing agent. The resulting particulate materials provided with ferrite coatings are separated by filtration and dried to obtain the desired products.
Preparation of particles treated by polymer compound The magnetic particles to be used in the present invention may be used after treating with a polymer compound. As the polymer compound, there may lae used, for example, a silane, nylon (trade name) or a polystyrene. As the method of silane treatment, for example, the acidic aqueous silylation method may be used. It can be accomplished by, firstly mixing ferrite coated particles and silane monomer in an acidic solution, and then treating the mixture at room temperature to 95° C under heating. As the silane monomer to be used, there may be used, for example, an organosilane such as p-aminophenyltrimethoxysilane, 3-aminopropyl-trimethoxysilane, N-2-aminoethyl-3-aminopropyl-trimethoxysilane, triamino-functional silane (HZNCH2CH2-NHCH2CH2NHCHZCHZCH2-Si- (OCH3) 3) , n-dodecyltriethoxysilane and n-hexyltrimethoxysilane. Further, in order to convert an end amino group of the silane into a carboxylic group, an acid anhydride can be reacted with silane-treated particles at room temperature. Also, for treating polyamide; ferrite coated particles are suspended in a l~ aqueous sodium carbonate solution, an appropriate amount of hexamethylenediamine is dissolved therein, and 5-fold amounts of a hexane-chloroform mixed solution (3 . 1) containing 8~ Tween 80 (trade name, produced by Kao Corp.) is mixed with the solution, and it then is subjected to ultrasonic treatment to form an emulsion. Then, by adding dropwise the same hexane-chloroform mixed solution as mentioned above containing sebacoyl dichloride with an equimolar amount of hexamethylenediamine, the desired particles can be obtained. Also, in the case of a polystyrene, it can be treated by employing the method known in the art. Further, magnetic particles can be directly coated by spraying or dipping in a polymer resin solution such as nylon (trade name) and a polystyrene.
The present invention relates to magnetic particles obtained by binding an antigen or an antibody to the ferrite coated particles or further polymer compound-treated particles obtained by the above method. As the antibody to be used, there may be mentioned, for example, a chemical such as theophylline, phenytoin and valproic acid; a low molecular hormone such as thyroxine, estrogen and estradiol; a cancer marker such as CEA and AFP; a virus antigen such as HIV, ATLA and HBV; a high molecular hormone such as TSH and "'Sf - ,.
insulin; a cytocain such as IL-1, IL-2 and IL-6; various kinds of gloss factor such as EGF and PDGF; and further an antibody to a suitable DNA, RNA, etc. of the above viruses.
Also, as the antigen to be used, there may be mentioned a virus such as HIV, ATLA and HBV; DNA of the above viruses; a high molecular hormone such as insulin and TSH.
As the bonding method, the physical absorption method or the chemical bonding method may be employed. The physical absorption method is carried out in an appropriate buffer solution by reacting the above particles and an antigen or an antibody. As the buffer solution to be used in this reaction, there may be mentioned a phosphate buffer solution, a tris-hydrochloride buffer solution and a carbonate buffer solution. The reaction can proceed easily by mixing both of the components at room temperature to obtain the desired product. Also, as the chemical bonding method, the carbodiimide method in the so-called peptide bonding method can be employed: Bonding can be carried out, for example, by adding an equiamount of a water-soluble carbodiimide to a dispersion of 0.1 to 5 $ of silylated particles under acidic conditions (pH 4 to 6), reacting at room temperature for 10 minutes to one hour, removing a supernatant, and then adding 0.01 to 10.0 mg/ml, preferably 0.1 to 5 mg/ml of an antibody or an antigen solution. The buffer to be used at this time is preferably a phosphate i.
2~~~5~
buffer. Also, as the other chemical bonding method, the method in which the reaction is carried out in the presence of a divalent cross-linking reagent such as glutaraldehyde and cyanuric chloride may be employed (see "Peptide Synthetic Method", published by Maruzene K.K. (published in 1975) and "Enzyme Immunoassay Method", published by Kyoritsu Shuppan K.K., "Protein, Nucleic acid, Enzyme", special issue No. 31 (1987)).
The magnetic particles produced as mentioned above had a constant particle size. These particles had not changed even when they were preserved in an appropriate protein solution such as BSA and globulin for one year.
The magnetic particles according to the present invention have a particle size of 0.2 um or more to 3 um or less. If the particle size becomes in excess of 3 um, floating time is short when they are used in immurio reaction so that sufficient reaction cannot be carried out. Also, if it is less than 0.2 um, magnetic separating efficiency after immunoassay becomes difficult.
Immunoassay method As the immunoassay method in accordance with the present invention, the radioactive immunoassay method and the enzyme immunoassay method can be used. These assay methods are the immunoassay methods using a label, and an antigen or an antibody to be assayed can be assayed by the sandwich method or the competition method.
The enzyme immunoassay method according to the present invention is, for example, carried out by reacting an antibody-bound magnetic particle and an enzyme-labelled antibody for 10 minutes to 3 hours. A reaction temperature when practicing the reaction is 4° C to 40° C, and preferably 25° G to 38° C. After washing an unreacted enzyme-labeled antibody, an amount of a ligand of specimen can be determined by measuring an amount of an antigen-bound enzyme bound to a solid phase, by adding an enzyme substrate and measuring an activity thereof. An enzyme to be used in the method of the present invention may include peroxidase, alkaline phosphatase, ~3-galactosidase and glucose-oxidase. At this time, it is needless to say that a substrate to be used should be that which is suitable for an enzyme to be used.
As such substrates, there may be used, for example, ABTS, luminol-H202 (for peroxidase), 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt (AMPPD), p-nitrophenylphosphate and methylumbelliferyl phosphate (for alkaline phosphatase), p-nitrophenyl-(3-0-glactose and methyl-umbelliferyl-(3-o-galactose (for (3-galactosidase). The measurement can be carried out by reacting at room temperature to 40° C for 1 minute to 18 hours; and then measuring an amount of color, fluorescence or luminescence generated. As the other method, the so-called rate method in which it is carried out at a temperature range of 4° C to 40° C under heating may be employed.
Also, the radioimmunoassay method in the immunoassay method is carried out by labelling a radioisotope such as lzsI in place of the above enzyme label. Operations are quite the same with the above enzyme immunoassay method, except for measuring radioactivity.
Also, radiolabelling of an antigen or an antibody can be readily accomplished by the already available Bolton-Hunter reagent. It can be prepared by, for example, adding the Bolton-Hunter reagent to an antigen or an antibody solution dissolved in a 0.1 M sodium hydrogen carbonate aqueous solution, and after l to 2 hours, removing unreacted Bolton-Hunter reagent by using a desalting column of G-25, etc. In addition, radiolabelling of 1251 can be easily carried out by employing the chloramine T method or the iododine method.
For effecting the immuno reaction, a sample is added to the magnetic particles of the present invention, and reacted at 4° C to 40° C, preferably 20° C to 38°
C for 1 to 18 hours. Thereafter, washing is carried out by a ~~ ~'4' physiological salt solution or distilled water, radiolabelled antibody is added to magnetic particles and reacted at 4° C to 40° C, preferably 20° C to 38°
C for 1 to 18 hours, washed with a physiological salt solution or distilled water and then determining its radioactivity. A
scintillation counter can be used for the measurement.
Also, the assay method of the present invention may be carried out by the chemiluminescent assay method in which isoluminol or acridine ester is labelled, or the fluorescent immunoassay method in which fluoresceine or rhodamine is labelled. During the procedures, labelling of a labelling substance can be easily carried out by employing the active ester method or the isocyanate method (see "Enzyme immunoassay method" (published by Igaku Shoin, 1987)).
Similarly, measurement of the antibody can be carried out by using the magnetic particles of the present invention, mixing these particles with a sample to react them at a room temperature to 37° C for one minute to 18 hours, washing with a physiological salt solution or distilled water, and then adding labelled-anti-human immunoglobulin antibody to react at a room temperature to 37° C for 1 minute to 18 hours, washing and measuring the activity of the labelled substance.
:4~
202b515 The present invention is an enzyme immunoassay method using particles comprising magnetic particles composed of an organic polymer as a core and a ferrite layer deposited on the surface thereof, and an antigen or antibody bound on the surface of the ferrite layer. These particles may be used as a solid phase of an immunoassay method.
L~VTMDT L~C'~
l In the following, the present invention will be explained by referring to Examples in more detail.
Example 1 Preparation of organic polymer particles In an apparatus for polymerization reaction having a stirrer, a thermometer, a monomer-dropping funnel, a reflux condenser, 20 a heating device and a nitrogen gas inlet tube was charged 230 parts of deionized water, followed by adding 1 part of a mixed monomer (A) composed of styrene, 2-ethylhexyl acrylate and ethyleneglycol dimethacrylate (80/10/10) and 10 parts of a 10 ~ aqueous ammonium persulfate solution, and then adding dropwise 99 parts of the above mixed monomer (A) over 3 hours to obtain a latex. When the particles were observed by 202b5Z5 electron microscope, they were substantially monodispersed and a particle size of 0.3 um.
Preparation of ferrite coated particles In a magnetic particle preparing apparatus having a stirrer, a thermometer, an oxidizing agent dropping funnel, a heating device and a nitrogen gas inlet tube was charged 100 parts of the above emulsion (30 ~ solid content) and degassed oxygen in the core emulsion by introducing N2 gas.
Then, previously prepared 100 parts (solid content: 40 parts) of ferrous chloride solution and 150 parts (solid content: 75 parts) of ammonium acetate were thrown in the apparatus and the mixture was sufficiently stirred at 70° C under heating.
Thereafter, while continuing stirring, a pH of the mixture was adjusted to 7.2 with aqueous ammonia.
To the solution was added dropwise 150 parts (solid content:
15 parts) of a sodium nitrite solution over about one hour.
During dropwise addition and reaction, a temperature of the mixture was maintained to 70° C and a pH in the range of 7.0 to 7.2 while continuing introduction of nitrogen gas and stirring to form ferrite coatings on the surfaces of said particles. After about 20 minutes, the solution was cooled, and repeated to filtering and washing with deionized water, °'~fi.
z 2~~515 and then taken out particles to obtain ferrite coated particles.
Example 2 Preparation of anti-TSH mouse IgG-bound magnetic particles To 4 ml of a 5 ~ ferrite coated particles-dispersed aqueous dispersion (20 mM phosphate buffer, pH 3.5) prepared in Example 1 was added 1 ml of anti-TSH mouse IgG (5 mg/ml), and the mixture was stirred by an end-over-end mixer at room temperature overnight. After separating this particle dispersion with a magnet having 3000 gauss at the surface thereof to a supernatant and particles, the supernatant was removed, and the particles were washed five times with a 2 BSA solution (0.1 M Tris-hydrochloric acid, 1 mM magnesium chloride and 0.1 mM zinc chloride, pH: 7.5). Then, the particles were dispersed in 5 ml of the similar BSA solution to prepare magnetic particles.
. 17 g':.y .
~r Example 3 Preparation of anti-CEA mouse IgG-bound magnetic particles To 4 ml of a 5 ~ ferrite coated particles-dispersed aqueous dispersion (20 mM phosphate buffer, pH 3.5) prepared in Example l was added 1 ml of anti-CEA mouse IgG (5 mg/ml), and the mixture was stirred by an end-over-end mixer at room temperature overnight. After separating this particle . dispersion with a magnet having 3000 gauss at the surface thereof to a supernatant and particles, the supernatant was removed, and the particles were washed five times with a 2 ~
BSA solution (0.1 M Tris-hydrochloric acid, 1 mM magnesium chloride and 0.1 mM zinc chloride, pH: 7.5). Then, the particles were dispersed in 5 ml of the similar BSA solution to prepare magnetic particles.
Example 4 Preparation of carboxylated-ferrite particles Carboxylated ferrite particles can be obtained by adding 50 ml of 3-aminopropyltriethoxysilane to 5 g of ferrite particles (polystyrene having an average particle size of the core of 0.3 um) of Example 1 which had been previously washed 5 times for each 60 seconds with distilled water by using an B
ultrasonic washing machine (Batt type, manufactured by Nippon Seiki Seisakusho K.K.1, further adding 30 ml of glacial acetic acid to react at room temperature for 3 hours, followed by washing and reacting with glutaric acid anhydride. Glacial acetic acid was added dropwise under ice-cooling and stirring, and washing was carried out each three times with distilled water, methanol and distilled water, and further five times with each 300 ml of 0.1 M sodium hydrogen carbonate solution. The reaction with glutaric acid was carried out by adding 2.85 g of glutaric acid anhydride to 100 ml-of 5 ~ by weight (0.1 M sodium hydrogen carbonate solution) particles and reacting for l0 minutes. After completion of the reaction, the mixture was washed three times with each 300 ml of 0.1 M sodium hydrogen carbonate solution, and further five times with distilled water. This was used'as carboxylated ferrite particles.
Example 5 Preparation of anti-TSH bound carboxylated-ferrite In 5 ml of 2O mM phosphate buffer (pH 4.5) was dispersed 50 mg of carboxylated ferrite particles prepared in Example 4, followed by adding 50 mg of water-soluble carbodiimide.
After reacting at room temperature for 20 minutes, the supernatant was removed, and 5 ml of anti-TSH mouse IgG
B
202~~i~
solution (1 mg/ml, 0.02 M phosphate buffer solution, pH:
4.5), and the mixture was stirred by an end-over-end mixer.
After 2 hours, these particles were washed five times with 2 ~ BSA solution (0.1 M Tris-HCl, 1 mM MgCl2, pH: 7.5) and dispersed in the similar BSA solution to obtain anti-TSH-mouse IgG sensitized carboxylated-ferrite particles.
Example 6 TSH assay using anti-TSH sensitized ferrite particles To a sample containing 15 ul of TSH (0, 10 uU/ml) was mixed ul of alkali phosphatase conjugate (conjugate concentration: 0.5 ug/ml, 0.1 M Tris-hydrochloric acid, 2 BSA, 1 mM MgCl2, 0.1 mM ZnCl2, pH: 7.5) to which anti-TSH Fab' is bound, and then 500 ul (0.02 ~ solution) of ferrite particles prepared in Example 2 on which anti-TSH mouse IgG
was coated was mixed to the above mixture, and the resulting mixture was allowed to stand at room temperature for 20 20 minutes. A tube containing the above mixture was contacted with a magnet having a surface magnetic field of 3000 gauss to attract ferrite particles and the supernatant was removed by decantation. Thereafter, 1 ml of 0.04 ~ physiological salt solution was added to the particles and the mixture was stirred. The tube was again contacted with the above mentioned magnet to separate the particles and a supernatant, 2~~65) and the supernatant was removed by decantation. These operations were repeated three times. To the tube containing these particles was added 200 ul of a substrate solution (0.1 M Tris-hydrochloric acid, 1 uM MgClz, 0.1 mM ZnCl2, pH: 9.8) containing 100 ug/ml of 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt (AMPPD) and the mixture was reacted at room temperature. After carrying out the reaction for 17 minutes, the sample was measured by a luminometer (manufactured by Belthold Co.).
In Table l, an S/N ratio of integrated value for 5 minutes was shown. For comparison, the results wherein ferrite particles produced by Advanced Magnetics Inc. [magnetic carrier for Affinity Chromatography (carboxyl group terminated)] were used are also shown.
Table 1 S/N ratio Magnification Ferrite coated particles 47.4 6.2 Particles produced by 7.6 1 Advanced Magnetics Co.
_ k~.~., , Example 7 202~51.~
TSH assay using carboxylated particles To a sample containing 15 ul of TSH (0, 10 uU/ml) was mixed 20 ul of alkali phosphatase conjugate (conjugate concentration: 0.5 ug/ml, 0.1 M Tris-hydrochloric acid, 2 BSA, 1 mM MgCl2, 0.1 mM ZnCl2, pH: 7.5) to which anti-TSH
Fab' is bound, and then 500 ul (0.02 % solution) of carboxylated ferrite particles prepared in Example 5 on which anti-TSH mouse IgG was coated was mixed to the above mixture, and the resulting mixture was allowed to stand at room temperature for 20 minutes. A tube containing the above mixture was contacted with a magnet having a surface magnetic field of 3000 gauss to attract ferrite particles and the supernatant was removed by decantation. Thereafter, 1 ml of 0.04 % physiological salt solution was added to the particles and the mixture was stirred. The tube was again contacted with the above mentioned magnet to separate the particles and a supernatant, and the supernatant was removed by decantation. These operations were repeated three times. To the tube containing these particles was added 200 ~Zl of a substrate solution (0.1 M Tris-hydrochloric acid, 1 ~.zM MgCl2, 0.1 mM ZnCl2, pH: 9.8) containing 100 ug/ml of AMPPD and the mixture was reacted at room temperature. After carrying out r s '~ _., .....>~
the reaction for 17 minutes, the sample was measured by a luminometer (manufactured by Belthold Co.).
In Table 2, an S/N ratio of integrated value for 5 minutes was shown. For comparison, the results wherein ferrite particles produced by Advanced Magnetics Inc. [magnetic carrier for Affinity Chromatography (carboxyl group terminated)] were used are also shown.
Table 2 S/N ratio Magnification Ferrite coated particles 78.2 10.0 Particles produced by 7.6 1 Advanced Magnetics Co.
Example 8 CEA assay using anti-CEA sensitized ferrite particles To a sample containing 15 ul of CEA (0, 25,50 ng/ml) was mixed 20 ul of alkali phosphatase conjugate (conjugate concentration: 0.2 ug/ml, 0.1 M Tris-hydrochloric acid, 2 ~ BSA, 1 mM MgCl2, 0.1 mM ZnCl2, pH: 7.5) to which anti-CEA Fab' is bound, and then 500 ul (0.02 ~ solution) of ferrite particles prepared in Example 3'on which anti-CEA
\.... 'b'~~~~...;.
r ~~~~~1 mouse IgG was coated was mixed to the above mixture, and the resulting mixture was allowed to stand at room temperature for 20 minutes. A tube containing the above mixture was contacted with a magnet having a surface magnetic field of 3000 gauss to attract ferrite particles and the supernatant was removed by decantation.
Thereafter, 1 ml of 0.04 ~ physiological salt solution was added to the particles and the mixture was stirred. The tube was again contacted with the above mentioned magnet to separate the particles and a supernatant, and the supernatant was removed by decantation. These operations were repeated three times. To the tube containing these particles was added 200 pl of a substrate solution (0.1 M
Tris-hydrochloric acid, 1 uM MgCl2, 0.1 mM ZnCl2, pH: 9.8) containing 100 ~Zg/ml of AMPPD and the mixture was reacted at room temperature. After carrying out the reaction for 17 minutes, the sample was measured by a luminometer (manufactured by Belthold Co.).
In Fig. 1, an S/N ratio of integrated value for 5 minutes is shown. For comparison, the results wherein ferrite particles produced by Advanced Magnetics Inc. [magnetic carrier for Affinity Chromatography (carboxyl group terminated)] were used are also shown.
.. . _. _.._. 2 4 ., ~(~~~515 Example 9 Comparison of magnetic separating rate of ferrite particles In a tube was charged 500 ul of 0.02 ~ anti-TSH mouse IgG
bound ferrite particles (2 ~ BSA, 0.1 M Tris-HC1, 1 mM
MgCl2, pH: 9.8), and the tube was contacted with a magnet having a surface magnetic field of 3000 gauss.
After 0, 10, 20, 30, 40 and 60 seconds of the contact, a supernatant was separated and an absorption at a wavelength of 660 nm was measured. The results of separating rate are shown in Fig. 2.
Example 10 Investigation of floating property of particles Anti-TSH mouse IgG bound ferrite particles (0.02 ~) were charged in a 1000 ul tube and allowed to stand at room temperature.
Supernatants at 0 minute and after 30 minutes were sampled and absorption at a wavelength of 660 nm was measured.
~_ _ 2 5 ~ r~
~,A>?:.~.. a -.:~~~5 i Its relative turbidity is shown in Table 3.
Table 3 Relative turbidit Ferrite coated particles 80 ~
Particles manufactured by 72 Advanced Magnetics Inc.
(The relative turbidity means a turbidity after "30 minutes"
when a turbidity at "0 minute after allowed to stand" as "100 ~" . ) The present invention relates to an enzyme immunoassay method using particles composed of a magnetic particle comprising an organic polymer as a core and ferrite coatings coated on the surface thereof, and an antigen or antibody bound to the surface of the magnetic particle. The particles according to the present invention have uniform particle size and are excellent in binding state of an antigen or antibody to the particles. Further, the particles according to the present invention have advantages that they are stable for a long period of time and thus can be preserved. An enzyme immunoassay method according to the present invention can be carried out by using the particles, rapidly and with high sensitivity.
Claims (25)
1. An immunoassay method including the steps of:
(a) reacting a sample containing an antigen with an antibody which specifically binds to said antigen, so as to bind said antigen to said antibody, wherein said antibody is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide composed of an iron oxide and at least one of iron, zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium and indium;
(b) measuring an amount of bound antigen; and (c) correlating the amount of bound antigen obtained in step (b) with an amount of antigen in the sample.
(a) reacting a sample containing an antigen with an antibody which specifically binds to said antigen, so as to bind said antigen to said antibody, wherein said antibody is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide composed of an iron oxide and at least one of iron, zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium and indium;
(b) measuring an amount of bound antigen; and (c) correlating the amount of bound antigen obtained in step (b) with an amount of antigen in the sample.
2. An immunoassay method including the steps of:
(a) reacting a sample containing an antigen with an antibody which specifically binds to said antigen, so as to bind said antigen to said antibody, wherein said antibody is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide formed by adding ferrous ions or ferrous ions and an ion selected from the group consisting of zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium, indium ions and mixtures thereof to deoxidized water in which cores of organic polymer are suspended to form a resulting solution, and subsequently adding an oxidizing agent solution to the resulting solution to provide a ferrite coating on said core:
(b) measuring an amount of bound antigen: and (c) correlating the amount of bound antigen obtained in step (b) with an amount of antigen in the sample.
(a) reacting a sample containing an antigen with an antibody which specifically binds to said antigen, so as to bind said antigen to said antibody, wherein said antibody is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide formed by adding ferrous ions or ferrous ions and an ion selected from the group consisting of zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium, indium ions and mixtures thereof to deoxidized water in which cores of organic polymer are suspended to form a resulting solution, and subsequently adding an oxidizing agent solution to the resulting solution to provide a ferrite coating on said core:
(b) measuring an amount of bound antigen: and (c) correlating the amount of bound antigen obtained in step (b) with an amount of antigen in the sample.
3. An immunoassay method including the steps of:
(a) reacting a sample containing an antibody with an antigen which specifically binds to said antibody, so as to bind said antibody to said antigen, wherein said antigen is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide composed of an iron oxide and at least one of iron, zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium and indium:
(b) measuring an amount of bound antibody: and (c) correlating the amount of bound antibody obtained in step (b) with an amount of antibody in the sample.
(a) reacting a sample containing an antibody with an antigen which specifically binds to said antibody, so as to bind said antibody to said antigen, wherein said antigen is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide composed of an iron oxide and at least one of iron, zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium and indium:
(b) measuring an amount of bound antibody: and (c) correlating the amount of bound antibody obtained in step (b) with an amount of antibody in the sample.
4. An immunoassay method including the steps of:
(a) reacting a sample containing an antibody with an antigen which specifically binds to said antibody, so as to bind said antibody to said antigen, wherein said antigen is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide formed by adding ferrous ions or ferrous ions and an ion selected from the group consisting of zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium, indium ions and mixtures thereof to deoxidized water in which cores of organic polymer are suspended to form a resulting solution, and subsequently adding an oxidizing agent solution to the resulting solution to provide a ferrite coating on said core;
(b) measuring an amount of bound antibody; and (c) correlating the amount of bound antibody obtained in step (b) with an amount of antibody in the sample.
(a) reacting a sample containing an antibody with an antigen which specifically binds to said antibody, so as to bind said antibody to said antigen, wherein said antigen is immobilized on a 0.2 to 3.0 µm magnetic particle comprising a core and a coating layer on the surface of said core, said core comprises an organic polymer, and said coating layer comprises a metal oxide formed by adding ferrous ions or ferrous ions and an ion selected from the group consisting of zinc, cobalt, nickel, manganese, copper, vanadium, antimony, lithium, molybdenum, titanium, rubidium, aluminum, silicon, chromium, tin, calcium, cadmium, indium ions and mixtures thereof to deoxidized water in which cores of organic polymer are suspended to form a resulting solution, and subsequently adding an oxidizing agent solution to the resulting solution to provide a ferrite coating on said core;
(b) measuring an amount of bound antibody; and (c) correlating the amount of bound antibody obtained in step (b) with an amount of antibody in the sample.
5. An immunoassay method according to claim 1 or 2, wherein said method is an enzyme immunoassay method.
6. An immunoassay method according to claim 3 or 4, wherein said method is an enzyme immunoassay method.
7. An immunoassay method according to claim 1, 2 or 5, wherein said particle is further coated with a polymer selected from the group consisting of silane, nylon and polystyrene, prior to immobilization of the antibody.
8. An immunoassay method according to claim 3, 4 or 6, wherein said particle is further coated with a polymer selected from the group consisting of silane, nylon and polystyrene, prior to immobilization of the antigen.
9. An immunoassay method according to any one of claims 1, 2, 5 or 7, wherein said organic polymer of the core comprises a polystyrene or a polymer comprising at least one of an acrylate and a methacrylate.
10. An immunoassay method according to any one of claims 3, 4, 6 or 8, wherein said organic polymer of the core comprises a polystyrene or a polymer comprising at least one of an acrylate and a methacrylate.
11. An immunoassay method according to any one of claims 1, 2, 5, 7 or 9, wherein said coating layer is a magnetite layer or a mixed crystal ferrite layer.
12. An immunoassay method according to any one of claims 3, 4, 6, 8 or 10, wherein said coating layer is a magnetite layer or a mixed crystal ferrite layer.
13. The immunoassay method according to claim 7, 9 or 11, wherein said sample comprises said antigen; said antibody is immobilized on said magnetic particle; and said method further comprises adding to the sample an enzyme-labeled antibody, which specifically binds to said antigen;
and separating unreacted enzyme-labeled antibody from the sample by washing out said unreacted enzyme-labeled antibody, adding an enzyme substrate specific for the enzyme, and measuring the activity of antibody-bound enzyme.
and separating unreacted enzyme-labeled antibody from the sample by washing out said unreacted enzyme-labeled antibody, adding an enzyme substrate specific for the enzyme, and measuring the activity of antibody-bound enzyme.
14. An immunoassay method according to claim 8, 10 or 12, wherein said sample comprises said antibody; said antigen is immobilized on said magnetic particle; and said method further comprises adding to the sample an enzyme-labeled antigen; which specifically binds to said antibody;
and separating unreacted enzyme-labeled antigen from the sample by washing out said unreacted enzyme-labeled antigen, adding an enzyme substrate specific for the enzyme, and measuring the activity of antigen-bound enzyme.
and separating unreacted enzyme-labeled antigen from the sample by washing out said unreacted enzyme-labeled antigen, adding an enzyme substrate specific for the enzyme, and measuring the activity of antigen-bound enzyme.
15. An immunoassay method according to claim 13, wherein said enzyme substrate is selected from the group consisting of (i) ABTS and luminol-H2O2 for peroxidase;
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
16. An immunoassay method according to claim 14, wherein said enzyme substrate is selected from the group consisting of (i) ABTS and luminol-H2O2 for peroxidase;
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
17. An immunoassy method according to claim 15, wherein said enzyme substrate is 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt.
18. An immunoassay method according to claim 16, wherein said enzyme substrate is 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt.
19. An immunoassay method according to any one of claims 5, 7, 9 or 11, wherein said sample comprises said antigen; said antibody is immobilized on said magnetic particle; and said method further comprises adding to the sample an enzyme-labeled antigen, which specifically binds to said antibody; and separating unreacted enzyme labeled antigen from the sample by washing out said unreacted enzyme-labeled antigen, adding an enzyme substrate specific for the enzyme, and measuring the activity of antigen-bound enzyme.
20. An immunoassay method according to any one of claims 6, 8, 10 or 12, wherein said sample comprises said antibody; said antigen is immobilized on said magnetic particle; and said method further comprises adding to the sample an enzyme-labeled antibody, which specifically binds to said antibody; and separating unreacted enzyme-labeled antibody from the sample by washing out said unreacted enzyme-labeled antibody, and adding an enzyme substrate specific for the enzyme and measuring the activity of antibody-bound enzyme.
21. An immunoassay method according to claim 19, wherein said enzyme substrate is selected from the group consisting of (i) ABTS and luminol-H2O2 for peroxidase;
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
22. An immunoassay method according to claim 20, wherein said enzyme substrate is selected from the group consisting of (i) ABTS and luminol-H2O2 for peroxidase;
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
(ii) 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt, p-nitrophenylphosphate and methylumbelliferyl phosphate for alkaline phosphatase; and (iii) p-nitrophenyl-.beta.-o-galactose and methylumbelliferyl-.beta.-o-galactose for .beta.-galactosidase.
23. An immunoassay method according to claim 21, wherein said enzyme substrate is 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt.
24. An immunoassay method according to claim 22, wherein said enzyme substrate is 3-(2'-spiroadamantane)-4-methoxy-4-(3"-phosphoryloxy)phenyl-1,2-dioxetane disodium salt.
25. A magnetic particle for an immunoassay method, the particle comprising an organic polymer core and an iron oxide-type ferrite coating layer formed on the surface of the core, having a particle size of 0.2 µm to 3 µm, and an antigen or an antibody bound onto the surface of the coating layer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1252051A JP2979414B2 (en) | 1989-09-29 | 1989-09-29 | Magnetic particles and immunoassay using the same |
| JP252051/1989 | 1989-09-29 |
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| Publication Number | Publication Date |
|---|---|
| CA2026515A1 CA2026515A1 (en) | 1991-03-30 |
| CA2026515C true CA2026515C (en) | 2001-12-25 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026515A Expired - Lifetime CA2026515C (en) | 1989-09-29 | 1990-09-28 | Immunoassay using magnetic particle |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5320944A (en) |
| EP (1) | EP0420186B1 (en) |
| JP (1) | JP2979414B2 (en) |
| KR (1) | KR100206159B1 (en) |
| AU (1) | AU641687B2 (en) |
| CA (1) | CA2026515C (en) |
| DE (1) | DE69021309T2 (en) |
| ES (1) | ES2077618T3 (en) |
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| AU620838B2 (en) * | 1987-10-26 | 1992-02-27 | Dade International Inc. | Process for producing magnetically responsive polymer particles and application thereof |
-
1989
- 1989-09-29 JP JP1252051A patent/JP2979414B2/en not_active Expired - Fee Related
-
1990
- 1990-09-26 DE DE69021309T patent/DE69021309T2/en not_active Expired - Lifetime
- 1990-09-26 EP EP90118468A patent/EP0420186B1/en not_active Expired - Lifetime
- 1990-09-26 ES ES90118468T patent/ES2077618T3/en not_active Expired - Lifetime
- 1990-09-27 AU AU63286/90A patent/AU641687B2/en not_active Expired
- 1990-09-28 CA CA002026515A patent/CA2026515C/en not_active Expired - Lifetime
- 1990-09-29 KR KR1019900015713A patent/KR100206159B1/en not_active IP Right Cessation
-
1992
- 1992-10-22 US US07/965,612 patent/US5320944A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ES2077618T3 (en) | 1995-12-01 |
| DE69021309D1 (en) | 1995-09-07 |
| EP0420186A2 (en) | 1991-04-03 |
| US5320944A (en) | 1994-06-14 |
| KR100206159B1 (en) | 1999-07-01 |
| JPH03115862A (en) | 1991-05-16 |
| CA2026515A1 (en) | 1991-03-30 |
| AU641687B2 (en) | 1993-09-30 |
| JP2979414B2 (en) | 1999-11-15 |
| AU6328690A (en) | 1991-04-11 |
| DE69021309T2 (en) | 1996-02-01 |
| KR910006725A (en) | 1991-04-29 |
| EP0420186B1 (en) | 1995-08-02 |
| EP0420186A3 (en) | 1991-07-31 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKEX | Expiry |