WO2015060269A1 - 被験物質の濃度測定方法および検出装置 - Google Patents
被験物質の濃度測定方法および検出装置 Download PDFInfo
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/82—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a precipitate or turbidity
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- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/26—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving oxidoreductase
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- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
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- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1717—Systems in which incident light is modified in accordance with the properties of the material investigated with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
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- 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
- G01N33/531—Production of immunochemical test materials
- G01N33/532—Production of labelled immunochemicals
- G01N33/535—Production of labelled immunochemicals with enzyme label or co-enzymes, co-factors, enzyme inhibitors or enzyme substrates
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- 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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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/1717—Systems in which incident light is modified in accordance with the properties of the material investigated with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
- G01N2021/1725—Modulation of properties by light, e.g. photoreflectance
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N2021/7769—Measurement method of reaction-produced change in sensor
- G01N2021/7773—Reflection
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/06—Illumination; Optics
- G01N2201/061—Sources
- G01N2201/06113—Coherent sources; lasers
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- G—PHYSICS
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- G01N2201/00—Features of devices classified in G01N21/00
- G01N2201/06—Illumination; Optics
- G01N2201/062—LED's
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
- G01N2333/90—Enzymes; Proenzymes
- G01N2333/902—Oxidoreductases (1.)
- G01N2333/904—Oxidoreductases (1.) acting on CHOH groups as donors, e.g. glucose oxidase, lactate dehydrogenase (1.1)
Definitions
- the present invention relates to a method for detecting a test substance using a polymerized substance producing (oxidation-reduction) enzyme such as peroxidase, and a detection apparatus used in the above method.
- a polymerized substance producing (oxidation-reduction) enzyme such as peroxidase
- a detection apparatus used in the above method.
- the ELISA method is a kind of immunological measurement method (immunoassay) that uses a combination of a specific binding reaction between an antigenic determinant of an antigen and an antibody and a color reaction by an enzyme labeled with the antibody or antigen.
- immunological measurement method immunological measurement method
- a highly specific antigen-antibody reaction is used, and the color development based on the enzyme reaction is converted into a signal for measurement, so that it can be detected with high sensitivity and has excellent quantitativeness.
- radioimmunoassay radioimmunoassay, RIA
- the ELISA method is used for diagnosis of biological substances such as antibodies, influenza viruses, plasma proteins, cytokines, DNA, peptides, ligands; chemical substances such as residual agricultural chemicals and environmental hormones contained in foods; diabetes, cancer, etc. It is widely used for detection and quantification of various test substances such as blood glucose and diagnostic substances such as tumor markers.
- the ELISA method is roughly classified into a direct adsorption method, a competitive method, and a sandwich method depending on the difference in measurement principle.
- the outline of each measurement method is as follows.
- a test substance is immobilized on a microplate or the like, and then an antibody labeled with an enzyme (enzyme-labeled antibody) is added to react with an antigen in the test substance (antigen-antibody reaction).
- an antibody labeled with an enzyme enzyme-labeled antibody
- an antigen in the test substance antigen-antibody reaction
- a chromogenic substrate for the labeled enzyme react, and measure the absorbance of the colored pigment using a colorimeter to determine the amount of antigen in the test substance.
- the direct adsorption method has drawbacks such as a low quantitative amount of protein.
- the competition method was developed to improve the above-mentioned drawbacks of the direct adsorption method, and is a method for detecting an antigen in a test substance with high sensitivity using one kind of antibody against the antigen.
- a test substance and an enzyme-labeled antigen are added to a microplate or the like on which an antibody is immobilized, and reacted competitively (antigen-antibody reaction).
- an enzyme chromogenic substrate is added and reacted, and the absorbance of the colored dye is measured using a colorimeter to determine the amount of antigen in the test substance.
- the sandwich method is a method for detecting an antigen in a test substance using two types of antibodies, and has an advantage of very high specificity. Specifically, a test substance is added to an antibody (primary antibody, capture antibody) immobilized on a microplate or the like and allowed to react (antigen-antibody reaction). Next, after removing the contaminants by washing, an enzyme-labeled antibody (secondary antibody) is further added and reacted at a site different from the antigen-antibody reaction. Thereby, a sandwich structure of primary antibody-antigen-secondary antibody is formed. After removing the contaminants by washing, an enzyme chromogenic substrate is added and reacted, and the absorbance of the colored dye is measured using a colorimeter to measure the amount of antigen in the test substance.
- an enzyme-labeled antibody secondary antibody
- an enzyme chromogenic substrate is added and reacted, and the absorbance of the colored dye is measured using a colorimeter to measure the amount of antigen in the test substance.
- HRP horseradish peroxidase
- H 2 O 2 substrate hydrogen peroxide
- peroxidases such as glutathione peroxidase and haloperoxidase are widely used for quantification of biological components such as glucose and cholesterol in addition to antibodies.
- Peroxidase has low substrate specificity for a substance to be oxidized, and various quantitative methods can be applied.
- HRP has a low molecular weight
- it is used as a labeling enzyme by binding to an antibody in an ELISA method, and is used in fields such as medicine, epidemiology, and clinical testing by combining with a coloring reagent (also called a chromogenic substrate).
- a coloring reagent also called a chromogenic substrate.
- o-PD o-phenylenediamine
- DAP obtained by the above reaction formula is an orange or red coloring substance, and an absorption peak near a wavelength of 420 nm increases with time.
- biological substances such as glucose and cholesterol can also be detected by measuring the absorbance based on this color reaction.
- the following is a color reaction using ⁇ -D-glucose and the enzyme glucose oxidase (GOD) that specifically acts only on ⁇ -D-glucose.
- GOD glucose oxidase
- ⁇ -D-glucose is oxidized by GOD
- D-glucono- ⁇ -lactone gluconic acid
- hydrogen peroxide H 2 O 2
- HRP hydrogen peroxide
- the ELISA method includes several methods.
- the color developed by an enzyme-labeled antibody or the like is spectroscopically measured using a colorimeter.
- spectroscopic measurement requires a plurality of devices such as a diffraction grating, an optical filter, and a high-sensitivity detector, and there is a problem that the device becomes large and expensive.
- Patent Document 1 an optical detection system based on a waveguide using a scanning light source
- Patent Document 2 a disk-type analysis chip
- Patent Document 3 an optical waveguide type antibody chip
- the ELISA method is extremely useful as a means capable of detecting and analyzing a very small amount of a test substance with high sensitivity by using an antigen-antibody reaction and a labeled enzyme.
- the spectroscopic measurement apparatus used for measuring the absorbance of the color developing substance based on the enzyme reaction has a problem that it is large and the measurement time is long.
- the above problem is not limited to immunoassays such as ELISA, but a method for detecting a test substance such as glucose by measuring the absorbance of a chromogenic substance produced by an enzyme reaction (in the sense that an enzyme is used, in a broad sense enzyme assay) In the same manner).
- the present invention has been made in view of the above circumstances, and an object of the present invention is to detect a test substance by utilizing color development by an enzyme reaction, or a specific interaction such as an antigen-antibody reaction and color development by an enzyme reaction. It is an object of the present invention to provide a method capable of quickly and sensitively detecting a test substance without using a spectroscopic measurement device.
- Another object of the present invention is to provide a detection apparatus for a test substance that is suitably used in the above method, and is small and has a short measurement time.
- the method for measuring the concentration of a test substance according to the present invention includes a step of generating a peroxide from a test substance, a oxidoreductase for generating a polymer substance, and the polymer substance generation in the peroxide.
- the test substance is a substance that generates a peroxide by an enzymatic reaction.
- a oxidoreductase for generating a polymer substance is added to a test substance, a substance having a specific interaction with the test substance After contacting the modified modifier, a step of contacting the peroxide and a substrate of the oxidoreductase for generating the polymer material to obtain the polymer material; irradiating the polymer material with light; And the step of recording the temporal change information of the intensity of the scattered light.
- the specific interaction with the test substance is an antigen-antibody reaction.
- the temporal change information constitutes a signal waveform, and from a predetermined time after the start of irradiation of the light to the test substance, until the signal waveform shows an extreme value.
- the method further includes the step of specifying the time.
- the step of obtaining the polymer substance is performed on a substrate.
- a first substrate on which at least one of the test substance and a group X substance consisting of a substance having a specific interaction with the test substance is present; the test substance, and the And a second substrate in which at least one of the group X substances consisting of a substance having a specific interaction with the test substance does not exist, and is irradiated with light from the second substrate.
- the substrate includes an X group substance existence region in which at least one of the test substance and an X group substance composed of a substance having a specific interaction with the test substance exists, And an X group substance non-existing region where no X group substance exists, and the light is irradiated to the X group substance non-existing region.
- a porous carrier is provided on the substrate, and the X group substance is fixed by the porous carrier.
- the detection apparatus of the present invention that has solved the above problems includes a light source capable of making light incident on a test substance, a photoelectric conversion element that detects scattered light from a polymerized substance derived from the test substance, and the photoelectric conversion element. And a recording medium for continuously recording an output signal for a predetermined time.
- the polymer substance derived from the test substance is present on the first surface side of the light transmitting substrate, and further includes a lens facing the second surface side of the light transmitting substrate.
- the time taken from a predetermined time after the start of irradiation of the light to the test substance-derived polymer substance until the signal waveform recorded on the recording medium shows an extreme value is calculated. It further has a calculation means for specifying.
- a group X substance comprising a polymer substance derived from the test substance and a substance having a specific interaction with the polymer substance derived from the test substance on the first surface side of the light transmitting substrate.
- the present invention it is possible to measure and detect the concentration of a test substance quickly and with high sensitivity, compared with a conventional method using a spectroscopic device.
- the present invention it is possible to provide a detection device that is smaller and less expensive and has a shorter measurement time than a conventional detection device using a spectroscopic device.
- FIG. 1 is a diagram comparing the method of the present invention with a conventional method for detecting ⁇ -D-glucose.
- FIG. 2 is a diagram showing a reaction mechanism inferred in the present invention.
- FIG. 3 is a diagram showing an embodiment of a detection device used in the present invention.
- FIG. 4 is an explanatory diagram of the substrate used in the experiment.
- FIG. 5A is a diagram showing the results of the absorption spectrum of the o-PD solution at each irradiation time when the o-PD solution is irradiated with a green LED.
- FIG. 1 is a diagram comparing the method of the present invention with a conventional method for detecting ⁇ -D-glucose.
- FIG. 2 is a diagram showing a reaction mechanism inferred in the present invention.
- FIG. 3 is a diagram showing an embodiment of a detection device used in the present invention.
- FIG. 4 is an explanatory diagram of the substrate used in the experiment.
- FIG. 5A
- FIG. 5B is a diagram showing the temporal change in the backscattered light intensity when the laser light is condensed on the o-PD solutions with different irradiation times and the backscattered light intensity is measured.
- FIG. 6 is a graph plotting the peak time of the backscattered light intensity against the peak absorbance of the o-PD solution.
- FIG. 7 (a) is a diagram showing the relationship between the laser irradiation time and the backscattered light intensity when green laser light is focused on an o-PD aqueous solution with various concentrations.
- FIG. 7B is an SEM photograph after the green laser is irradiated for 80 seconds for each concentration of o-PD aqueous solution.
- FIG. 8A to 8F are photographs in which a green laser is focused on a 1 mM o-PD aqueous solution and an image of reflected light is taken every 4 seconds.
- FIG. 9A is a diagram showing the measurement procedure of this experiment.
- FIG. 9B is an AFM observation image when the laser is irradiated for 4 to 16 seconds.
- FIG. 9C is a diagram showing the relationship between the laser irradiation time, the backscattered light intensity, and the height of the polymer.
- FIG. 10 is a diagram schematically showing light detected in the present invention.
- FIG. 11A is an explanatory diagram of a model sample sandwiched between a glass substrate and water used in the experiment.
- FIG. 11B is a diagram showing the relationship between the thickness of the polymer thin film and the reflectance in the model sample.
- FIG. 12A is a diagram showing the measurement procedure of this experiment.
- FIG. 12B is a diagram showing temporal changes in the backscattered light intensity when the laser light is focused on a solution in which DAP having various concentrations is mixed in a 1 mM o-PD solution.
- FIG. 12C is a diagram showing the relationship between the concentration of DAP and the peak time of the backscattered light intensity.
- FIG. 13 (a) is a diagram showing the relationship between the laser irradiation time and the backscattered light intensity in a mixture of HRP solution, hydrogen peroxide of various concentrations, and o-PD solution.
- FIG. 12A is a diagram showing the measurement procedure of this experiment.
- FIG. 12B is a diagram showing temporal changes in the backscattered light intensity when the laser light is focused on a solution in which DAP having various concentrations is mixed in a
- FIG. 13B is a diagram showing the relationship between the hydrogen peroxide concentration and the peak time of the backscattered light intensity.
- FIG. 14A is an SEM observation image when the laser beam is focused on the o-PD solution.
- FIG. 14B is an SEM observation image of the nanostructure formed at the focal point when the laser beam is focused on the mixed solution of the o-PD solution, the HRP solution, and the hydrogen peroxide.
- FIG. 15A is a diagram showing the measurement procedure of this experiment.
- FIG. 15B is a diagram showing the relationship between the laser irradiation time and the backscattered light intensity when a laser is irradiated on a mixed solution of various concentrations of aqueous glucose solution, GOD, and HRP.
- FIG. 14A is an SEM observation image when the laser beam is focused on the o-PD solution.
- FIG. 14B is an SEM observation image of the nanostructure formed at the focal point when the laser beam is focused on the mixed solution of the o-PD solution
- FIG. 15C is a graph plotting the time when the first peak of the backscattered light intensity appears for each glucose concentration.
- FIG. 16A is a diagram showing the measurement procedure of this experiment.
- FIG. 16B is a diagram showing the results of absorption spectra in a mixed solution of glucose aqueous solutions having various concentrations, GOD, and HRP.
- FIG.16 (c) is the figure which plotted the peak absorbance with respect to each glucose concentration.
- FIG. 17 is a diagram showing temporal changes in backscattered light intensity when various concentrations of glucose are irradiated with laser having a wavelength of 473 nm.
- FIG. 18 is a diagram showing temporal changes in the backscattered light intensity when a laser having a wavelength of 532 nm is irradiated to glucose of various concentrations.
- FIG. 19 is a diagram showing temporal changes in the backscattered light intensity when a laser having a wavelength of 633 nm is irradiated to glucose of various concentrations.
- FIG. 20 is a diagram showing the peak time of the backscattered light intensity with respect to the glucose concentration at each wavelength.
- FIG. 21 shows the absorption spectrum of the o-PD solution (3.8 mM) used in the experiment.
- FIG. 22 shows the relationship between the absorption spectrum of the o-PD aqueous solution at each wavelength (left axis) and the backscattered light intensity spectrum (right axis) of the nanostructure formed by focusing the laser on the o-PD aqueous solution.
- FIG. 23 is a schematic diagram showing the progress of the oxidative polymerization reaction of o-PD by focused laser light.
- FIG. 24 is a diagram for explaining an energy diagram of a photosensitizing reaction.
- FIG. 25 shows the photosensitization effect of methylene blue using a 633 nm He—Ne laser.
- FIG. 26 shows mixed solutions obtained by adding 20 ⁇ L of an o-PD / blue solution to various concentrations of aqueous glucose solution, GOD, and HRP solution. It is a figure which shows the time change of backscattered light intensity.
- FIG. 27 is a graph plotting the peak time of the backscattered light intensity with respect to each glucose concentration.
- FIG. 28 is a diagram showing temporal changes in backscattered light intensity in a mixed solution obtained by adding an o-PD solution to various concentrations of ethanol, an HRP solution, and an AOD solution.
- FIG. 29 is a graph plotting the peak time of the backscattered light intensity with respect to each ethanol concentration.
- FIG. 30 (a) is a schematic diagram of a measurement method in the ELISA method (part 1).
- FIG. 30B is a diagram showing the relationship between the laser irradiation time and the backscattered light intensity.
- FIG. 30 (c) is a diagram showing the relationship between the time (predetermined time) until the backscattered light intensity reflected light intensity once decreases and increases to the original intensity, and the concentration of the HRP-labeled anti-IgG antibody. is there.
- FIG. 31 (a) is a schematic view of a measurement method in the ELISA method (part 2).
- FIG. 31B is a diagram showing the relationship between the laser irradiation time and the backscattered light intensity.
- FIG. 31 (c) is a diagram showing the relationship between the time (predetermined time) until the backscattered light intensity reflected light intensity decreases once and increases to the original intensity again, and the concentration of the HRP-labeled anti-IgG antibody. is there.
- FIG. 32 is a view showing a substrate having an antibody presence region A in which an antibody is present and an antibody non-existence region B in which no antibody is present.
- FIG. 33 is a view showing a substrate on which an antibody is immobilized by a donut-shaped porous carrier provided on the substrate.
- FIG. 34 is a view showing a substrate in which a spacer is interposed between the porous carrier and the substrate.
- FIG. 35 is a diagram showing a substrate obtained by deforming a porous carrier into a convex shape.
- FIG. 36 is a graph showing the results of a conventional absorbance measurement method in the experiment described in 7-1.
- FIG. 37 is a diagram showing the results of the method of the present invention in the experiment described in 7-1.
- FIG. 37A shows the relationship between the laser irradiation time and the backscattered light intensity.
- FIG. 37 (b) is a diagram showing the relationship between the peak time of the backscattered light intensity and the concentration of the HRP-labeled anti-IgG antibody.
- FIG. 38 is a graph showing the results of a conventional absorbance measurement method in the experiment described in 7-2.
- FIG. 39 is a diagram showing the results of the method of the present invention in the experiment described in 7-2.
- FIG. 39A is a diagram showing the relationship between the laser irradiation time and the backscattered light intensity.
- FIG. 39B is a diagram showing the relationship between the time (predetermined time) until the backscattered light intensity once decreases and then increases again to the original intensity, and the CRP concentration.
- FIG. 40 is a diagram for explaining the experimental procedure described in 7-3.
- FIG. 41 is a diagram showing the relationship between the peak time of backscattered light intensity and the concentration of HRP-labeled anti-IgG antibody in the experiment described in 7-3.
- the present inventors have intensively studied to solve the above problems.
- the peroxide and the redox for producing the polymerized substance The present invention has found that the intended purpose is achieved by irradiating a polymer substance obtained by contacting an enzyme substrate with light and recording information on temporal change in intensity of scattered light from the irradiation point. Was completed.
- oxidizing reductase for generating polymerized substance “substrate for generating reductase for generating polymerized substance”, “polymerized substance”, and “polymer” are defined as follows.
- the above-mentioned “oxidizing reductase for producing a polymerized substance” is an enzyme for obtaining a polymerized substance by a polymerization reaction.
- Peroxidase an enzyme for obtaining a polymerized substance by a polymerization reaction.
- this invention is not limited to this, What is necessary is just an enzyme which superposes
- the above-mentioned “substrate for oxidoreductase for producing a polymer substance” is for obtaining a polymer substance by the above polymerization reaction.
- the substrate may be simply referred to as a polymerization substrate.
- the “polymeric substance” is obtained by a reaction between the above-described oxidoreductase for producing a polymer substance and a substrate for the oxidoreductase for producing a polymer substance.
- a dimer (dimer) such as diaminophenazine (DAP) is used. ).
- the “polymer” is formed by absorbing light such as laser light from the polymerized substance as shown in FIGS. 1 and 2 to be described later.
- the polymer having a higher degree of polymerization of the “polymer” and agglomerated in the light-collecting spot on the substrate (polymer that scatters light) is particularly called a “nanostructure”.
- the measurement method of the present invention includes the following first method and second method.
- First method Generating peroxide from the test substance; Contacting the peroxide with a oxidoreductase for producing a polymer substance and a substrate of the oxidoreductase for producing the polymer substance to obtain a polymer substance; Irradiating the polymerized material with light and recording temporal change information of intensity of scattered light from the irradiation point; A method for measuring the concentration of a test substance containing
- test substance is brought into contact with a substance having a specific interaction with the test substance and a modified substance modified with a oxidoreductase for generating a polymer substance, and then a peroxide, and the redox for generating the polymer substance
- contacting the enzyme substrate to obtain a polymerized material Irradiating the polymerized material with light and recording temporal change information of intensity of scattered light from the irradiation point;
- a method for measuring the concentration of a test substance comprising:
- the first method and the second method are different in the step of obtaining a polymer material. That is, the first method uses a test substance that generates a peroxide by a biochemical reaction such as an enzyme reaction, and obtains a polymerized substance using the peroxide derived from the test substance.
- the second method uses a specific interaction (for example, antigen-antibody reaction) with a test substance, and the test substance used in the second method is the first method. It is not limited to the peroxide-producing test substance used in 1.
- the second method is useful as an alternative to the conventional ELISA method.
- test substance applicable to the above method can be detected and quantified with high sensitivity.
- test substance include test substances that can be detected by ELISA (for example, biological substances such as antibodies, influenza viruses, C-reactive proteins, plasma proteins, cytokines, DNA, peptides, ligands; foods, etc.) Chemical substances such as residual agricultural chemicals and environmental hormones; blood sugar used for diagnosis of diabetes, cancer, etc., diagnostic substances such as tumor markers), biological substances such as glucose, cholesterol, histamine; ethanol, formic acid, etc. It is possible to detect and quantify various test substances with high sensitivity, such as substances that are oxidized by enzymatic reaction.
- the step of obtaining the polymerized material does not characterize the present invention, and any known method can be applied as long as the following requirements are satisfied.
- the step of generating a peroxide from a test substance and the peroxide is brought into contact with a oxidoreductase for producing a polymer substance and a substrate for the oxidoreductase for producing the polymer substance
- Step of obtaining a polymer substance a polymer substance is obtained by reacting an enzyme with a peroxide derived from a test substance and dimerizing a polymer substrate along with the oxidation-reduction reaction of the enzyme.
- the test substance used in the above method is not particularly limited as long as it generates peroxide.
- the peroxide include inorganic peroxides such as hydrogen peroxide and sodium peroxide, and organic peroxides such as benzoyl peroxide and cumene hydroperoxide.
- the peroxide can be obtained, for example, by an enzyme reaction in which an enzyme is added to a test substance.
- the test substance include glucose, ethanol, cholesterol, formic acid and the like.
- glucose oxidase in the case of glucose glucose oxidase in the case of glucose
- glucose and glucose oxidase react to produce The hydrogen peroxide thus reacted reacts with the oxidoreductase for producing the polymer substance and the substrate for the oxidoreductase for producing the polymer substance.
- the present invention is not limited to this.
- the test substance is brought into contact with a substance having a specific interaction with the test substance and a modified substance in which a oxidoreductase for generating a polymer substance is modified, and then a peroxide. And a step of contacting the substrate of the oxidoreductase for producing the polymer substance to obtain the polymer substance
- the second method is the above-mentioned in that the polymer substrate is converted into a polymer substance accompanying the redox reaction of the enzyme.
- the premise is that, instead of using a peroxide derived from a test substance as in the first method, a specific interaction between the test substance and the test substance is performed.
- the “specific interaction with the test substance” includes, for example, an antigen-antibody reaction.
- the “substance having a specific interaction with the test substance” includes, for example, an antibody or antigen to the substance to be examined.
- the above-mentioned “modified substance in which a oxidoreductase for generating a polymer substance is modified with a substance having a specific interaction with the test substance” means an antibody or an antigen against the test substance labeled with an oxidoreductase or the like. Is mentioned.
- an antibody (primary antibody) against a test substance may be reacted sequentially with an antibody labeled with a oxidoreductase for generating a polymer substance and a substrate of the enzyme.
- the “antibody labeled with a oxidoreductase for producing a polymer substance” means an antibody that results in an antibody labeled with the enzyme. Therefore, at the time of use, the enzyme may be directly labeled on the antibody, or may not be labeled. Since the former oxidoreductase-labeled antibody is expensive, an antibody labeled with the oxidoreductase can be used by reacting the antibody with the oxidoreductase during use, as in the latter. Further, the enzyme may be covalently bound to an antibody or an antigen against the test substance. Alternatively, an antibody (secondary antibody) or antigen that recognizes an antibody (primary antibody) against the test substance may be labeled with the above enzyme.
- (III) A step of irradiating the polymerized material with light and recording temporal change information of the intensity of scattered light from the irradiation point (a step common to the first and second methods)
- the polymer material is irradiated with light.
- Oxidative polymerization proceeds by irradiation of light, and the polymer material absorbs light to form a polymer, thereby increasing the degree of polymerization.
- the polymer is aggregated in a focused spot on the light transmitting substrate to form a nanostructure (polymer that scatters light).
- the scattered light includes reflected light, back-reflected light, and back-scattered light.
- laser light is preferably used as the light. In light irradiation, it is preferable to collect light at the interface between a substrate such as a glass substrate and a solution containing a test substance-derived polymer substance.
- the time change information constitutes a signal waveform, and the time taken for the signal waveform to show an extreme value from a predetermined time after the start of irradiation of the light to the test substance is specified.
- the method further includes the step of:
- FIGS. 1 and 2 show examples in which HRP is used as a redox enzyme for generating a polymer substance, hydrogen peroxide is used as a substrate for HRP, o-PD is used as a coloring substrate for the redox enzyme, and laser light is used as light.
- the present invention is not limited to this.
- FIG. 1 schematically shows a state where o-PD polymer aggregates are formed by irradiating a polymer substance (DAP) generated by a series of reactions used for detecting ⁇ -D-glucose described above with laser light.
- DAP polymer substance
- FIG. 1 schematically shows a state where o-PD polymer aggregates are formed by irradiating a polymer substance (DAP) generated by a series of reactions used for detecting ⁇ -D-glucose described above with laser light.
- DAP polymer substance
- the absorbance of the DAP (dimer) of the polymerized substance produced by the oxidation reaction of o-PD was measured using a spectroscopic device to quantify the concentration of the test substance.
- the DAP is irradiated with laser light to advance the oxidative polymerization reaction, and the temporal change information of the intensity of scattered light from the irradiation point of the generated polymer aggregate (nanostructure) is recorded. To do.
- Examples of the temporal change information include a peak time until the peak intensity of the scattered light is obtained, and a time required for the signal waveform to show an extreme value from a predetermined time after the start of laser light irradiation. .
- the concentration of a test substance can be measured rapidly and with high sensitivity, compared with the conventional method.
- the laser light used in the above process is preferably a laser in the visible light range from the viewpoint of measurement sensitivity.
- a green laser having a wavelength of 500 to 550 nm is preferably used.
- a photosensitizer such as methylene blue or a porphyrin-based dye
- a laser having a longer wavelength region for example, a red laser having a wavelength of 600 to 700 nm
- practicality is improved, for example, the range of usable measurement wavelengths is widened.
- FIG. 2 shows an example in which a sample solution containing a test substance (specifically, a solution containing HRP, a color developing substrate o-PD and hydrogen peroxide) is used for the light transmitting substrate.
- a test substance specifically, a solution containing HRP, a color developing substrate o-PD and hydrogen peroxide
- a predetermined amount of the sample solution is dropped onto the substrate (see (i) of FIG. 2).
- the oxidative polymerization reaction of HRP changes o-PD to dimer 2,3-diaminophenazine (DAP) having light absorption.
- DAP dimer 2,3-diaminophenazine
- Oxidative polymerization reaction by HRP is further accelerated by the high oxidizing power of the active oxygen species generated in this way, and a polymer aggregate of o-PD is formed at the condensing point of the laser beam ((iii in FIG. 2).
- FIG. 2 (iii) shows the structure of the polymer aggregate of o-PD, but this is merely an example of an expected structure and is not intended to be limited thereto.
- the thus obtained o-PD polymer aggregate changes the intensity of scattered light from the irradiation point (condensing point) of laser reflected light.
- the intensity of the scattered light is measured, and the temporal change information of the intensity of the scattered light from the irradiation point is recorded.
- the temporal change information of the intensity of the scattered light for example, the peak time until the peak intensity is obtained can be mentioned.
- the peak time has a good correlation with the concentration of the o-PD solution, hydrogen peroxide, and the like. It is assumed that it can be detected quantitatively well.
- peak intensity includes both extreme maximum and minimum extreme values. This is because both extreme values can be obtained depending on the composition of the sample solution containing the test substance, the concentration of the test substance, and the like, as shown in the experimental examples described later.
- the peak intensity may be the first peak intensity or any peak intensity such as the second time and the third time.
- the extreme value within ⁇ 10% (more preferably within ⁇ 7%, more preferably within ⁇ 5%) of the scattering intensity at the start of laser light irradiation is It may be excluded from the extreme values in the present invention.
- the differential value is a negative value in a predetermined section (for example, 5 bits). It is also possible to specify a portion where a positive value has changed in a predetermined section (for example, 5 bits).
- the detection apparatus of the present invention includes a light source capable of entering light into a test substance, a photoelectric conversion element that detects scattered light from a polymerized substance derived from the test substance, and a signal output from the photoelectric conversion element for a predetermined time. It has a feature in that it has a recording medium for continuous recording.
- the detection device of the present invention is preferably a device for detecting a test substance existing on the first surface side of the light transmission substrate, and a lens facing the second surface side of the light transmission substrate;
- a laser light source capable of making light incident on the light transmissive substrate through the lens, and light scattered from a polymerized substance derived from a test substance existing on the first surface side of the light transmissive substrate are transmitted through the lens.
- a photoelectric conversion element to be detected and a medium for continuously recording a signal output from the photoelectric conversion element for a predetermined time are provided.
- the test substance in the detection apparatus of the present invention is not limited to the test substance used in the first and second methods described above, and a substance from which a polymer substance derived from the test substance can be obtained by absorbing light. means.
- the light-transmitting substrate refers to an object that can transmit light, but preferably transmits light having a wavelength of 532 nm by 85% or more, more preferably 90% or more, and even more preferably 95% or more. .
- a glass substrate, a plastic, etc. are mentioned, for example.
- the shape of the light transmitting substrate is preferably a flat plate shape.
- the test substance is detected based on the intensity of the scattered light from the test substance existing on the first surface side of the light transmitting substrate, the amount of light detected by scattering or refraction by the light transmitting substrate itself is detected. This is to avoid a decrease as much as possible.
- the light transmitting substrate is preferably thin, for example, 0.5 mm or less, and more preferably 0.2 mm or less. Although there is no particularly preferred lower limit to the thickness of the light transmitting substrate, in order to fulfill the function of holding the test substance, for example, it is 0.05 mm or more, preferably 0.1 mm or more. There is no particular limitation on the wavelength and intensity of the laser light, and any laser can be used as long as it promotes the polymerization of the polymer substance. As the photoelectric conversion element, a photomultiplier tube, a photodiode, a phototransistor, a solid-state imaging element, or the like can be used.
- any recording medium regardless of volatile / nonvolatile such as various flash memories, a hard disk built in a personal computer, a DRAM, or an SRAM. Can be used.
- the detection apparatus of the present invention further includes a calculation means for specifying a time taken from a predetermined time after the start of irradiation of the laser beam to the test substance until the signal waveform recorded on the recording medium shows an extreme value. You may have.
- a single signal waveform can be obtained by using a photoelectric conversion element having one pixel unit, and the extreme value can be specified from the signal waveform.
- a photoelectric conversion element which is an image sensor having a plurality of pixel units, such as a solid-state imaging device
- a signal waveform is once obtained for each pixel, and an average value of these signal waveforms is taken to obtain a single It is also possible to obtain a signal waveform and specify an extreme value from the signal waveform.
- time from the predetermined time after the start of irradiation is specified in order to be able to discard a part of the unstable time data immediately after the start of irradiation.
- “after irradiation start” includes “at the start of irradiation”.
- the time calculation means for calculating the time required from the start of irradiation of the laser beam to the light transmitting substrate until the output signal of the photoelectric conversion element shows an extreme value may be realized by hardware, but on software It is preferable to carry out by treatment. It is preferable to use backscattered light as light scattered from the test substance. This is because at least a part of the optical system for making the laser light incident on the test substance and the optical system for detecting the light scattered from the test substance can be shared, which is useful for downsizing the entire apparatus.
- o-Phenylenediamine (oxidoreductase substrate): o-PD 2,3-diaminophenazine (polymerized material): DAP Polyphenylenediamine: Polymeric glucose oxidase: GOD Horseradish peroxidase (oxidoreductase): HRP Alcohol oxidase: AOD
- the o-PD solution used in the experiment contains a small amount of DAP due to natural oxidation.
- Reagents and measuring apparatus used in the experiment 1-1.
- Reagent o-Phenylenediamine (Wako) Glucose oxidase (162 units / mg, Toyobo Co., Ltd.) Horseradish peroxidase (100 units / mg, Wako) Methylene blue (Wako)
- citrate buffer (pH 4.6) was used and dissolved to a predetermined concentration.
- Alcohol oxidase Pichia pastoris, 38 units / mL, SIGMA-ALDRICH
- Ethanol 99.5%, Wako
- Micro cover glass 17 (size 24 mm ⁇ 36 mm, thickness 0.12 to 0.17 mm, MATSANAMI) was washed with a detergent (decon 90, Decon Laboratories Limited), dried, and punched thereon with a diameter of 3.5 mm
- a silicon sheet 15 (thickness 0.2 mm, Asone) having 9 to 12 holes was placed thereon, and the multi-well substrate (hereinafter sometimes abbreviated as substrate) in FIG. 4 was produced.
- 16 is a solution to be measured.
- FIG. 3 shows a schematic diagram of the laser condensing device used in this experiment.
- the laser light source 1 includes a DPSS laser with a wavelength of 473 nm (SDL-473-050TL, Shanghai Dream Lasers Technology), and a YAG laser with a wavelength of 532 nm (SDL-532-020TL, Shanghai Dream Lasers Technology 33 laser). -2066-000, COHERENT).
- the laser beam was expanded by the beam expander 2 and then passed through the ND filter 3 and introduced into the inverted microscope 5 (IX70-S1F2, OLYMPUS).
- the laser beam is reflected by the half mirror 6 (70% reflection), and the upper surface (substrate-solution interface) of the substrate 9 set on the stage 8 of the inverted microscope using the objective lens 7 (UPlanFL N, 60x, OLYMPUS). It was condensed to. Polymer nanostructures 10 are formed in the focused spot.
- Table 1 shows the laser intensity at the condensing point of each laser light source.
- the backscattered light passes through the optical fiber 12 by the coupler 11, is detected by a photomultiplier tube (Hamamatsu Photonics, R1166) 13, converted into an electric signal, and then transmitted to the computer (PC) via the data recording expansion board 14. Is output.
- a mechanical shutter 4 that can be controlled to open and close by an external input is placed on the optical path of the laser so that it can be automatically controlled by a program from a computer.
- a green LED (M530L2, wavelength 530 nm, intensity 220 mW, Thorlabs) was used for coloring o-PD by light irradiation.
- the objective lens 7 is designed so that the diameter of the laser condensing spot reflected on the upper surface of the substrate is reduced. The height of was adjusted. After the shutter 4 was closed and the laser beam was cut off, 10 to 20 ⁇ L of a sample solution containing o-PD was dropped into the well of the substrate 9. The measurement time was adjusted to 1 to 5 minutes by setting the measurement rate of the voltage from the photomultiplier tube 13 to 50 Hz and the number of measurement points to 3000 to 15000 according to the program.
- the shutter 4 When the shutter 4 was opened by computer operation, the laser was focused on the sample, and measurement of the backscattered light intensity associated with the formation of the polyphenylenediamine nanostructure was started.
- the mechanical shutter 4 was automatically closed when the set time had elapsed and the measurement was completed.
- SEM scanning electron microscope
- a neo-osmium coater (Meiwaforsys Inc., NeoC-ST) was used to deposit an osmium metal conductive film on the surface of the substrate with a thickness of about 2.5 nm to impart conductivity to the surface, and then by SEM. Measurements were made.
- O-PD Oxidation Polymerization Reaction by Laser Irradiation instead of using the HRP enzyme reaction, o-PD is irradiated with a green LED to form DAP, and by light absorption of DAP contained in the o-PD solution, It shows that the nanostructure which is a polymer aggregate is obtained.
- the polymerized material in the o-PD solution is important for the formation of the nanostructure.
- FIG. 6 is a graph plotting the peak time of the backscattered light intensity against the peak absorbance. From the above figure, it can be seen that the peak time of the backscattered light intensity becomes earlier as the o-PD solution is oxidized and the absorbance increases.
- FIG. 7 (b) is an SEM photograph of the o-PD aqueous solution with each concentration after being irradiated with a green laser for 80 seconds.
- FIG. 7B shows that a polymer structure is formed at the focused spot position.
- the size of the polymer increases as the concentration of the o-PD aqueous solution increases. This is because the higher the concentration of the o-PD aqueous solution, the faster the formation speed of the nanostructure.
- the concentration of the o-PD aqueous solution was 4 mM, an irregularly shaped structure was formed. This is considered to be the reason why the temporal change in the backscattered light intensity becomes discontinuous in the vicinity of 50 seconds, as shown in FIG.
- FIGS. 8A to 8F are CCD cameras in which a green laser is focused on a 1 mM o-PD aqueous solution and an image of reflected light is attached to the optical microscope every 4 seconds. The pictures were taken sequentially. The green spot at the center is the reflected light from the laser focusing point. It can be seen that the backscattered light intensity increases from FIG. 8A to FIG. 8D and then decreases from FIG. 8D to FIG. 8F.
- FIG. 9A shows the measurement procedure of this experiment.
- a 1 mM o-PD aqueous solution was irradiated with a 200 mW / cm 2 green laser (wavelength 532 nm) for about 10 minutes to prepare an o-PD solution containing DAP.
- 20 ⁇ L of the o-PD solution thus obtained was dropped on the substrate, the laser beam was condensed, and the temporal change in reflected light intensity was measured for 20 seconds.
- the same experiment was performed by changing the irradiation time of the laser beam, and the shape of the nanostructure formed at the laser condensing position on the glass substrate by each laser irradiation time was changed to an atomic force microscope (hereinafter referred to as AFM). (It may be abbreviated.) (SII, SPI-4000).
- AFM measurement was performed in a tapping mode using a Si cantilever.
- FIG. 9B is an AFM observation image when the laser is irradiated for 4 to 16 seconds. From these figures, it can be seen that as the laser irradiation time increases, the size of the nanostructure increases and grows.
- FIG. 9C is a graph plotting the laser irradiation time on the horizontal axis, the backscattered light intensity on the left vertical axis, and the height of the nanostructure on the right vertical axis.
- the time (first peak time) at which the backscattered light intensity is first maximized represents the time until the polymer becomes large to a certain height. From the above figure, it can be seen that the height of the nanostructure is 80 nm when the backscattered light intensity takes a maximum value, and the height of the nanostructure grows to 180 nm when it takes a minimum value.
- the light detected in the present invention is, as shown in FIG. 10, superposition of the reflected light at the substrate-nanostructure interface of the focused laser and the reflected light at the structure-solution interface. Accordingly, the phase of light changes with the growth of the nanostructure, and the intensity of the backscattered light becomes a maximum when the phases of the two waves coincide with each other, and becomes a minimum when the phase is shifted by a half wavelength. And it is thought that it will increase again by the further phase change.
- FIG. 11A A model sample (a polymer thin film sandwiched between a glass substrate (refractive index 1.52) and water (refractive index 1.33)) shown in FIG. 11A is prepared, and the complex refractive index and film thickness of the polymer thin film are parameters. As a result, the reflectance when light having a wavelength of 532 nm was incident from the glass substrate side was calculated.
- FIG. 11B shows the relationship between the film thickness and the reflectance when the complex refractive index of the polymer thin film is 1.7-0.2i, 1.6-0.2i, and 1.5-0.2i. .
- the reflectance repeatedly increases and decreases as the thickness of the polymer thin film increases. This is due to the interference of light reflected at the two interfaces of the polymer film.
- the reflectance takes a maximum value near the film thickness of 70 to 100 nm and 240 to 290 nm, and becomes a minimum near 160 to 200 nm. This indicates the relationship between the height of the polymer and the laser irradiation time. Similar to the experimental results investigated. That is, it is understood that the temporal change in the backscattered light intensity in this experiment is caused by the growth of the nanostructure formed in the focused laser spot. The smaller the real part of the refractive index, the greater the decrease in reflectivity when the film thickness of the polymer thin film increases from zero.
- FIG. 12A shows the measurement procedure of this experiment.
- 0-750 ⁇ M DAP (specifically 0 M, 75 pM, 750 pM, 75 nM, 7.5 mM, 750 mM) was mixed with 1 mM o-PD solution to prepare a total of 6 types of solutions.
- 20 mL was dropped on the substrate, 2 mW laser light was condensed with an objective lens, and the temporal change in the backscattered light intensity was measured.
- the result is shown in FIG. From the above figure, it can be seen that the higher the DAP concentration, the earlier the time (peak time) at which the backscattered light intensity first reaches its maximum.
- FIG. 12 (c) shows the relationship between the concentration of DAP and the peak time of the backscattered light intensity. From the above figure, it was found that both have a good correlation, and that the DAP concentration can be measured with good quantitativeness by detecting the peak time at which the backscattered light intensity is first maximized.
- O-PD Oxidation Polymerization Reaction by Enzymatic Reaction
- an enzyme promotes the oxidation polymerization reaction of o-PD.
- active oxygen species are generated by light absorption of DAP obtained by an oxidative polymerization reaction by an enzyme.
- Oxidative polymerization proceeds due to the high oxidizing power of active oxygen, and a nanostructure that is a polymer aggregate is formed at the focal point. This nanostructure changes the intensity of laser reflected light.
- FIG. 13 (a) shows the temporal change of the backscattered light intensity obtained in this way. From the figure, it can be seen that the peak (maximum value) of the backscattered light intensity increases and the peak time becomes faster as the concentration of hydrogen peroxide increases.
- FIG. 13B shows a graph plotting the peak time of the backscattered light intensity with respect to the hydrogen peroxide concentration. From the figure, it can be seen that hydrogen peroxide can be quantified in the concentration range of 3.1 to 200 ⁇ M by the above method. This is because o-PD is oxidized by HRP and hydrogen peroxide to generate DAP.
- FIG. 14 (a) is an SEM observation image when only the o-PD solution is used
- FIG. 14 (b) is an SEM observation image when the HRP solution and hydrogen peroxide are added to the o-PD solution.
- the left side is a view of the nanostructure measured from above
- the right side is a view inclined by 45 °.
- the formation rate of the polymer is increased by the enzyme reaction, and a polymer having a large size is formed.
- the promotion of the oxidative polymerization reaction by the enzyme occurs in the height direction rather than the diameter direction. This is presumed to be because the oxidative polymerization reaction proceeds in the laser focused spot.
- FIG. 15 (a) shows the measurement procedure of this experiment. Specifically, 20 ⁇ L of an aqueous glucose solution (0 to 1 mM) and 20 ⁇ L of a mixture of GOD and HRP at 1: 1 (hereinafter abbreviated as GOD / HRP) were mixed and allowed to stand for 1 minute. 20 ⁇ L was taken from the mixed solution to which 20 ⁇ L of o-PD solution (1 mM) was added, dropped onto the substrate, and the backscattered light intensity was measured. The backscattered light intensity was similarly measured using ribose and lactose aqueous solution (5 mM) having no activity on GOD as a control.
- GOD / HRP a mixture of GOD and HRP at 1: 1
- FIG. 15B shows a temporal change in the obtained backscattered light intensity. As the glucose concentration increased, the maximum value of the backscattered light intensity (initial peak intensity) appeared earlier.
- FIG. 15 (c) shows a graph plotting the time at which the first peak of the backscattered light intensity appears for each glucose concentration. From the above figure, it was found that there was a clear correlation between the two, and glucose could be quantified in the concentration range of 100 nM to 1 mM. This is considered to be because the formation rate of o-PD to the polymer depends on the glucose concentration, so that the glucose concentration could be quantified from the temporal change of the backscattered light intensity. On the other hand, when the same reflected light intensity was measured using ribose and lactose (5 mM) as controls instead of glucose, the peak of the backscattered light intensity appeared at almost the same time as the glucose concentration of 100 nM. This is considered because GOD has a slight activity with respect to ribose and lactose.
- the glucose concentration can be measured specifically with high sensitivity (detection sensitivity: 100 nM to 1 mM) using the specificity of GOD.
- FIG. 16A shows the measurement procedure of this experiment. Specifically, 300 ⁇ L of an aqueous glucose solution (0 to 1 mM) and 300 ⁇ L of a GOD / HRP solution were mixed in a measuring cell of a spectrophotometer and left to stand for 1 minute. To this, 300 ⁇ L of o-PD solution (1 mM) was added and mixed, and the absorption spectrum was measured with a spectrophotometer.
- FIG. 16B shows the obtained absorption spectrum.
- FIG. 16C shows a graph in which the peak absorbance with respect to each glucose concentration is plotted.
- glucose can be detected 1000 times more sensitive than the conventional method.
- Table 2 shows a comparison between the method of the present invention and the conventional method. Compared with the conventional method, the glucose detection method according to the present invention is extremely excellent in that it requires a small amount of sample and has high detection sensitivity.
- a comparison with a glucose detection method using a commercially available glucose detection kit using a colorimetric method was performed.
- Table 3 shows the results of comparison with the method of the present invention in terms of temperature, measurement time, required sample amount, and glucose detection sensitivity.
- the commercially available glucose detection kit needs to be heated to 37 ° C., and the measurement takes 5 minutes or more.
- a glucose concentration of 200 ⁇ M to 39 mM can be detected with a 200 ⁇ L sample.
- the method of the present invention it is possible to measure at normal temperature without the need for heating, and it only takes about 1 to 2 minutes from the start of measurement. Furthermore, according to the method of the present invention, a glucose concentration of 100 nM to 1 mM can be quantified with a sample of 20 ⁇ L or less. Therefore, according to this invention, it turned out that glucose can be quantified rapidly and with high sensitivity compared with the case where a commercially available kit is used.
- FIG. 17 shows the temporal changes in the obtained backscattered light intensity.
- FIG. 20 shows the peak time of the backscattered light intensity with respect to the glucose concentration at each wavelength.
- the concentration range of glucose was 1 ⁇ M to 1 mM at a wavelength of 473 nm, 100 nM to 1 mM at a wavelength of 532 nm, and 0.5 to 2.5 mM at a wavelength of 633 nm. Therefore, it was found that green laser light having a wavelength of 532 nm is most suitable for the detection of glucose under the conditions of this experiment.
- FIG. 21 shows the absorption spectrum of the o-PD solution (3.8 mM) used in this experiment.
- the absorption spectrum of the o-PD solution has a peak in the vicinity of a wavelength of 450 nm, and the absorbance at each laser wavelength is 0.056 (wavelength 473 nm), 0.017 (wavelength 532 nm), 0.007 (wavelength 633 nm). Since the o-PD aqueous solution contains DAP formed by natural oxidation by oxygen in the air, it is considered that an absorption spectrum of DAP having a peak near 450 nm was obtained.
- FIG. 22 shows the absorption spectrum (left axis) of the o-PD aqueous solution and the backscattered light of the nanostructure formed by dropping the o-PD aqueous solution onto the substrate and condensing a laser having a wavelength of 532 nm.
- the intensity spectrum (right axis) is shown. Since the nanostructure formed by the above method has a nano-level size of 1 ⁇ m or less and an absorption spectrum cannot be measured, the scattering spectrum was measured by irradiating a halogen lamp with a dark field condenser lens.
- the scattering peak of the nanostructure formed at the condensing point is about 620 nm, which is longer than the peak of the absorption spectrum of dimer (DAP) in the o-PD solution. Since the scattering spectrum of the fine particles gives the same information as the absorption spectrum, it can be seen from the result of the scattering spectrum that the formed nanostructure absorbs light in a longer wavelength region more strongly than DAP. This is presumably because the o-PD is polymerized to increase the ⁇ -electron conjugate length and shift the absorption peak to the longer wavelength side.
- the laser with a wavelength of 532 nm could be measured with the highest sensitivity.
- a wavelength of 473 nm DAP shows strong light absorption, but a polymer having a long ⁇ electron conjugate length hardly absorbs light.
- the wavelength is 633 nm, DAP hardly absorbs light.
- Table 4 summarizes the results of the absorbance of the o-PD solution and the scattering intensity of the nanostructure at each wavelength.
- FIG. 23 is a schematic diagram showing the progress of the oxidative polymerization reaction of o-PD by focused laser light.
- the oxidation polymerization proceeds due to the light absorption of the dimer (DAP).
- DAP dimer
- the ratio of light absorption by the nanostructure Becomes larger. For this reason, it is considered that light absorption by both the dimer and the nanostructure in the o-PD solution is important for the method of the present invention. Therefore, as shown in Table 4 described above, it is considered that a green laser beam having a wavelength of 532 nm that absorbs both of them is most suitable for the detection of glucose.
- Oxygen molecules have a triplet state in the ground state, and singlet oxygen corresponding to an excited state is a useful oxidizing agent.
- the triplet state of a dye molecule such as methylene blue has an excitation energy approximately equal to the energy difference between singlet oxygen and triplet oxygen.
- the dye molecule is photoexcited, it transitions to the triplet state by intersystem crossing.
- the triplet state dye collides with triplet oxygen, exchange of electrons and energy occurs, and the dye returns to the ground state, and at the same time, triplet oxygen transitions to singlet oxygen.
- Oxidation by singlet oxygen generated by photoexcitation in this way is a typical mechanism of the photooxidation reaction, and a dye used for generating singlet oxygen is called a photosensitizer.
- a He—Ne laser having a wavelength of 633 nm that hardly absorbs o-PD dimer (DAP) was used to examine the photosensitization effect by methylene blue. Specifically, it was dissolved in a citrate buffer so that the concentration of methylene blue was 200 ⁇ M, and the concentration of the methylene blue solution was adjusted to 0.2 mM. Next, o-PD (4 mM) and the above methylene blue solution (0.2 mM) are mixed, and a mixed solution of o-PD (1 mM) + methylene blue (18.75 ⁇ M) (hereinafter abbreviated as o-PD / blue solution). .)
- FIG. 25 shows the absorption spectrum of the o-PD / blue solution thus obtained.
- methylene blue was added to the o-PD solution, an absorption peak appeared on the long wavelength side in addition to the original absorption of o-PD.
- FIG. 26 shows the temporal change of the obtained backscattered light intensity.
- FIG. 27 shows a graph plotting the peak time of the backscattered light intensity with respect to each glucose concentration.
- the detection sensitivity of glucose was improved by adding methylene blue, and the glucose concentration of 0.25 to 1 mM could be quantified. This indicates that the oxidation reaction by singlet oxygen generated by light absorption is involved in polymer formation by a focused laser.
- the above results also show that the present invention can be applied to a measurement system using an inexpensive semiconductor laser (LD) having a wavelength of 650 nm by using a photosensitizer such as methylene blue.
- LD inexpensive semiconductor laser
- methylene blue was used as a photosensitizer, but in addition, o-PD dimer (DAP) and polymers also act as photosensitizers and promote the oxidative polymerization of o-PD itself. It is done.
- DAP o-PD dimer
- ethanol was detected by the method of the present invention.
- the reaction formula of ethanol and AOD, o-PD and HRP is shown below.
- Ethanol was diluted with pure water to prepare 5 types of ethanol having a concentration of 0 to 100 mM.
- AOD solution was prepared by dissolving AOD in citrate buffer to a concentration of 100 units / mL.
- FIG. 28 shows the temporal change of the obtained backscattered light intensity.
- FIG. 29 the graph which plotted the peak time of the backscattered light intensity with respect to each ethanol concentration is shown.
- sample solution used for production of an IgG antibody-immobilized substrate was prepared as follows. First, an IgG antibody (ChromPure Human IgG, whole molecule, Jackson ImmunoResearch Laboratories, Inc., 11.8 mg / mL) used as a receptor is dissolved in HEPES buffer (10 mM, pH 7.25) so that the concentration becomes 100 ⁇ g / mL. did.
- IgG antibody ChromPure Human IgG, whole molecule, Jackson ImmunoResearch Laboratories, Inc., 11.8 mg / mL
- HEPES buffer 10 mM, pH 7.25
- HRP-labeled anti-IgG antibody (Rabbit polyclonal Secondary to Human IgG-H & L (HRP), pre-adsorbed, 0.5 mg / mL) was dissolved in pure water as a detection antigen to prepare an aqueous solution with a concentration of 10 ng / mL.
- the aqueous solution was repeatedly diluted 10 times with pure water to prepare 11 types of HRP-labeled anti-IgG antibody aqueous solutions having a concentration of 10 fg / mL to 10 ng / mL.
- N-Hydroxysuccinimide hereinafter referred to as NHS
- Dojindo 1-ethyl-3- (3-dimethylaminopropyl) carbohydride hydrochloride
- WSC 1-ethyl-3- (3-dimethylaminopropyl) carbohydride hydrochloride
- WSC 1-ethyl-3- (3-dimethylaminopropyl) carbohydride hydrochloride
- WSC 1-ethyl-3- (3-dimethylaminopropyl) carbohydride hydrochloride
- the mixed solution was prepared as follows. First, it melt
- a microscope cover glass (size 24 mm ⁇ 36 mm, thickness 0.12 to 0.17 mm, MATUNAMI) washed with a detergent was further washed using a plasma dry cleaner (PDC2102Z, Yamato Scientific Co., Ltd.).
- the cover glass was soaked in triethoxysilane (98% or more, SIGMA-ALDRICH) diluted 100 times with ethanol (3-Aminopropyl) for 30 minutes, washed with ethanol, and dried. Then, the cover glass was treated with aminosilane by heating at 120 ° C. for 2 hours in a dry oven (DX31, Yamato).
- a silicon sheet having 9 to 12 holes with a diameter of 3.5 mm was punched on the cover glass to form a multiwell substrate.
- 10 microliters of NHS / WSC solutions and 990 microliters of IgG antibody solutions were mixed, 20 microliters was dripped at each well, and it was left to incubate for 30 minutes.
- the substrate was washed and dried, and then 20 ⁇ L of a blocking reagent (ELISA ULTRABLOCK, AbD serotec) was added dropwise, and left undisturbed for 30 minutes to block unreacted amino groups.
- the thus prepared IgG antibody-immobilized substrate was stored in a cool and dark place until use.
- FIG. 30 (a) shows a schematic diagram according to this measurement method.
- An IgG antibody was immobilized on a glass substrate, and an HRP-labeled anti-IgG antibody that specifically binds to the IgG antibody was detected. Specifically, 20 ⁇ L each of HRP-labeled anti-IgG antibody solutions (10 fg / ml to 10 ng / ml) having different concentrations are dropped onto the IgG antibody-immobilized substrate prepared as described above, and left for 30 minutes at constant temperature, and then phosphoric acid is added. Washed with buffer solution and dried.
- reaction solution a mixed solution of o-PD (1 mM) and hydrogen peroxide (0.1 mM) is used as a reaction solution, 20 ⁇ L of the reaction solution is dropped on each substrate and left to stand for 1 minute, and then a 20 mW laser beam is emitted. The light was collected and the change in backscattered light intensity was measured. The result is shown in FIG. As shown in the above figure, the higher the concentration of the HRP-labeled anti-IgG antibody solution dropped on the substrate, the earlier the change in the backscattered light intensity appeared.
- FIG. 30 (c) shows the time when the backscattered light intensity once decreases and increases again to the original intensity (denoted as “predetermined time” on the vertical axis in the figure), and the HRP-labeled anti-IgG. It is a graph which shows the relationship with the density
- FIG. 31 (a) shows a schematic view of this measurement method.
- FIG. 31 (c) shows the time when the backscattered light intensity decreases once and increases again to the original intensity (described as “predetermined time” on the vertical axis in the figure), and the HRP-labeled anti-IgG. It is a graph which shows the relationship with the density
- FIG. 32 shows an example in which the antibody 23 is immobilized on the substrate 21, but the present invention is not limited to this.
- the substrate includes an X group substance existing region in which at least one of the X group substances consisting of a test substance and a substance having a specific interaction with the test substance (for example, antigen, antibody) exists, and the X group substance And a group X substance non-existing region that does not exist.
- the test substance for example, antigen, antibody
- a donut-shaped porous carrier 22 may be provided on the substrate 21, and the antibody 23 may be immobilized (adsorbed) by the porous carrier 22.
- FIG. 33 shows a state where receptors such as antibodies and antigens are adsorbed to the porous carrier 22.
- the portion where the porous carrier 22 is provided (outside) is the antibody existing region A, and the portion where the porous carrier is not provided (center portion) is the antibody non-existing region B.
- the material of the porous carrier 22 is not particularly limited as long as the antibody 23 can be easily immobilized, and the polymer formed in the antibody existing region can easily enter the antibody non-existing region. And fluorinated polyvinylidyne.
- the porous carrier 22 may be prevented from touching the condensing spot portion.
- the spacer 24 may be interposed between the porous carrier 22 and the substrate 21 so that the antibody does not exist at the focal point.
- the spacer 24 include polymer fine particles.
- the shape of the porous carrier 22 may be deformed into a convex shape as shown in FIG. 35 (by providing a cavity at the focused spot position) so that no antibody is present at the focused point.
- the substrate on which the antibody exists and the substrate on which the antibody does not exist are overlapped as shown in FIG. 40, and light is irradiated from the substrate on which the antibody does not exist. You may make it do.
- This method also proved that the test substance can be quantitatively measured with high sensitivity because no antibody is present at the focal point. Details of the experimental method and experimental results will be described later in 7-3. This is explained in the column. 40 shows an example in which the antibody 25 is immobilized on the cover glass 17 used as a substrate, but the present invention is not limited to this.
- a substrate on which at least one group X substance consisting of a test substance and a substance having a specific interaction with the test substance for example, an antigen
- the ELISA method uses a microplate on which an antibody to be detected is immobilized, an enzyme-labeled antibody (secondary antibody), a solution necessary for dilution or blocking, and reacts with an enzyme to develop color or fluorescent material.
- an enzyme-labeled antibody secondary antibody
- a reagent kit containing a chromogenic substrate to be produced is often used. Therefore, in the following, a comparative experiment between the conventional absorbance measurement method and the backscattered light intensity measurement method of the present invention was performed using a commercially available ELISA kit.
- FIG. 36 is a graph showing the relationship between the absorbance and the concentration of the HRP-labeled anti-IgG antibody.
- FIG. 37 is a graph showing the relationship between the time when the first peak of the backscattered light intensity appears (described as “peak time” on the vertical axis in the figure) and the concentration of the HRP-labeled anti-IgG antibody. Comparing these figures, a clear difference was observed between the two at a trace level where the HRP-labeled anti-IgG antibody concentration was 100 pg / mL or less. Therefore, it has been found that if the method of the present invention is used, it is possible to perform quantitative measurement at a very small concentration of, for example, 10 pg / mL or more, which is difficult with the conventional absorbance method.
- CRP C-reactive protein
- reaction solution a reaction solution [3,3 ′, 5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide mixed solution attached to the kit used in this experiment was used. ] was dropped into each well and allowed to stand at room temperature for 1 hour, and then 100 ⁇ L of the reaction stop solution attached to the Kit was dropped into each well. Absorbance at a wavelength of 405 nm in each well was measured using a microplate reader (Corona Electric, SH-1000).
- FIG. 38 is a graph showing the relationship between absorbance and CRP concentration.
- FIG. 39 shows the relationship between the time when the backscattered light intensity decreases once and increases again to the original intensity (denoted as “predetermined time” on the vertical axis) and the CRP concentration. It is a graph.
- the exact measurement sensitivity depends on the ELISA kit used, but if the method of the present invention is used, quantitative measurement of CRP at a trace concentration of, for example, 500 pg / mL or more, which was difficult with the conventional absorbance method, is possible. I understood that.
- the stationary substrate 27 is turned over, and a 1 mm thick silicon rubber sheet is adhered to both ends as spacers 24 (see (5) in FIG. 40).
- the same cover glass 28 (clean substrate without a polystyrene thin film) used for the production of the substrate was placed on top of each other.
- a laser (wavelength 532 nm, intensity 2.6 mW) is collected on the solid-liquid interface between the cover glass 28 and the polymer substance-containing solution 26 using a 60 ⁇ objective lens.
- the backscattered light intensity change was measured. That is, according to this experimental method, as shown in FIG. 40 (5), the laser is focused on the solid-liquid interface between the clean cover glass 28 on which the antibody is not solid-phased and the polymer-containing solution 26. , Nanostructures can be formed.
- FIG. 41 is a graph showing the relationship between the time when the first peak of the backscattered light intensity appears (described as “peak time” on the vertical axis in the figure) and the concentration of HRP-labeled anti-IgG antibody (secondary antibody). .
- peak time the time when the first peak of the backscattered light intensity appears
- concentration of HRP-labeled anti-IgG antibody secondary antibody
- the detection method of the present invention uses the DAP (dimer) in the o-PD solution and the condensed light. It was strongly suggested that light absorption by both of the polymers formed at the spots is important. Furthermore, ethanol could be detected with good quantitativeness by the method of the present invention.
- the method of the present invention can also be applied to an immunoassay.
- 10 pg / mL to 10 ⁇ g / mL of HRP-labeled anti-IgG antibody could be detected. .
- the detection sensitivity of the HRP-labeled anti-IgG antibody can be further improved by appropriately controlling the concentration of the sample solution containing the test substance, the antibody immobilization method on the substrate, and the like.
- a rapid, high-sensitivity, and portable ELISA measurement system can be realized by downsizing the measurement apparatus.
- the method of the present invention can also be applied to, for example, a multi-sensor chip in which a plurality of enzymes are immobilized on a single substrate. Therefore, the technology of the present invention is extremely useful for developing a small, inexpensive, and simple biosensing system capable of detecting a very small amount of a test substance.
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Abstract
Description
(i)被験物質から過酸化物を発生させ、当該過酸化物に、重合物質生成用酸化還元酵素、および前記重合物質生成用酸化還元酵素の基質を接触させて得られる重合物質、または(ii)被験物質に、当該被験物質に対して特異的な相互作用を有する物質に重合物質生成用酸化還元酵素が修飾された修飾物質を接触させた後、過酸化物、および重合物質生成用酸化還元酵素の基質を接触させて得られる重合物質に光を照射して、照射点からの散乱光の強度の時間的変化情報を記録することによって所期の目的が達成されることを見出し、本発明を完成した。
(1)第1の方法:
被験物質から過酸化物を発生させる工程と、
前記過酸化物に、重合物質生成用酸化還元酵素、および前記重合物質生成用酸化還元酵素の基質を接触させて重合物質を得る工程と、
前記重合物質に光を照射して、照射点からの散乱光の強度の時間的変化情報を記録する工程と、
を含む被験物質の濃度測定方法。
被験物質に、前記被験物質に対して特異的な相互作用を有する物質に重合物質生成用酸化還元酵素が修飾された修飾物質を接触させた後、過酸化物、および前記重合物質生成用酸化還元酵素の基質を接触させて重合物質を得る工程と、
前記重合物質に光を照射して、照射点からの散乱光の強度の時間的変化情報を記録する工程と、
を含むことを特徴とする被験物質の濃度測定方法。
この工程は、被験物質由来の過酸化物に酵素を反応させ、酵素の酸化還元反応に伴って重合基質を二量化するなどして重合物質を得るものである。
前述したように上記第2の方法は、酵素の酸化還元反応に伴う重合基質の重合物質化を行なう点では上記第1の方法と共通するが、その前提として、上記第1の方法のように、被験物質由来の過酸化物を用いるのではなく、被験物質と、被験物質に対して特異的な相互作用を有する物質に重合物質生成用酸化還元酵素が修飾された修飾物質を混合し、得られた物質に過酸化物および重合基質を混合したものを用いる点で、上記第1の方法と相違する。
上記工程を詳しく述べると、まず、上記重合物質に光を照射する。光の照射により酸化重合が進み、上記重合物質が光を吸収して重合体が形成され、重合度が高められる。その重合体が、光透過基体上の集光スポット内で凝集してナノ構造体(光を散乱する重合体)が形成される。上記散乱光には、反射光、後方反射光、後方散乱光も含まれる。また、散乱光強度の変化を精度良く測定するには、上記光として、レーザー光が好ましく用いられる。また、光の照射に当たっては、ガラス基板などの基体と被験物質由来の重合物質を含む溶液との界面に集光させることが好ましい。
o-フェニレンジアミン(酸化還元酵素の基質):o-PD
2,3-ジアミノフェナジン(重合物質):DAP
ポリフェニレンジアミン:重合体
グルコースオキシダーゼ:GOD
西洋ワサビペルオキシダーゼ(酸化還元酵素):HRP
アルコールオキシダーゼ:AOD
1-1.試薬
o-フェニレンジアミン(Wako)
グルコースオキシダーゼ(162unit/mg、東洋紡績株式会社)
西洋ワサビペルオキシダーゼ(100unit/mg、Wako)
メチレンブルー(Wako)
これらの溶媒にはクエン酸バッファー(pH4.6)を用い、所定濃度となるように溶解した。
アルコールオキシダーゼ(Pichia pastoris、38unit/mL、SIGMA-ALDRICH)
エタノール(99.5%、Wako)
マイクロカバーガラス17(サイズ24mm×36mm、厚さ0.12~0.17mm、MATSUNAMI)を洗剤(decon90、Decon Laboratories Limited)で洗浄して乾燥し、その上にパンチで直径3.5mmの穴を9~12個開けたシリコンシート15(厚さ0.2mm、Asone)を載せ、図4のマルチウェル基板(以下、基板と略記する場合がある。)を作製した。図中、16は測定対象の溶液である。
1-3-1.測定装置
本実験に用いたレーザー集光装置の概略図を図3に示す。レーザー光源1には波長473nmのDPSSレーザー(SDL-473-050TL、Shanghai Dream Lasers Technology)、波長532nmのYAGレーザー(SDL-532-020TL、Shanghai Dream Lasers Technology)、波長633nmのHe-Neレーザー(31-2066-000、COHERENT)を用いた。レーザー光をビームエキスパンダー2で拡げた後、NDフィルター3を通し、倒立型顕微鏡5(IX70-S1F2、OLYMPUS)へ導入した。レーザー光はハーフミラー6(70%反射)で反射され、対物レンズ7(UPlanFL N、60x、OLYMPUS)を用いて倒立型顕微鏡のステージ8上にセットした基板9の上面(基板-溶液の界面)へ集光させた。集光スポットには重合体のナノ構造体10が形成される。表1に各レーザー光源の集光点でのレーザー強度を示す。後方散乱光は、カップラー11により光ファイバー12を通り、光電子増倍管(Hamamatu Photonics、R1166)13で検出され、電気信号に変換された後、データ収録用拡張ボード14を介してコンピュータ(PC)に出力される。レーザーの光路上には外部入力で開閉を制御できるメカニカルシャッター4を置き、コンピュータからプログラムで自動制御できるようにした。
基板9を倒立型顕微鏡5のステージ上に固定し、レーザー光を基板上面に集光するため、基板上面で反射したレーザー集光スポット径が小さくなるように対物レンズ7の高さを調整した。シャッター4を閉じ、レーザー光を遮断してからo-PDを含む試料溶液を基板9のウェルに10~20μL滴下した。プログラムにより光電子増倍管13からの電圧の測定レートを50Hz、測定ポイント数を3000~15000に設定することで測定時間を1~5分に調整した。コンピュータの操作によりシャッター4を開くと、レーザーが試料に集光され、ポリフェニレンジアミンナノ構造形成に伴う後方散乱光強度の測定を開始した。メカニカルシャッター4は設定した時間が経過すると自動的に閉じて測定を終了した。
比較のため、o-PDの酸化によって生成したDAP(ダイマー)の吸収スペクトルを分光光度計で測定した。吸収スペクトルの測定には分光光度計(UV-2550、SHIMADZU)を用いた。試料と対照用の純水をそれぞれ測定用セル(10×10×45mm、ディスポセルUV、ニッコー・ハンセン株式会社)に入れ、分光光度計にセットする。そして波長300~900nmの範囲でサンプリングピッチを0.5nm、スキャンスピードを高速に設定して試料の吸収スペクトルを測定した。
基板上に形成した重合体を、走査型電子顕微鏡(Scanning Electron Microscope、以下、SEMと略記する。)(FEI、DB-235)を用いて観察した。SEMは、電子線を絞った電子ビームを測定する試料に照射させ、その試料から放出される2次電子を検出することで試料を観察することが出来る電子顕微鏡の一つである。SEMは電子ビームを試料に照射するため、試料表面に導電性が必要である。そのため、本実験ではネオオスミウムコーター(メイワフォーシス株式会社、NeoC-ST)を用い、基板表面にオスミウム金属導電被膜を約2.5nm堆積形成させて、表面に導電性を付与させてから、SEMによる測定を行った。
ここでは、HRP酵素反応を用いる代わりに、o-PDに緑色LEDを照射してDAPを形成させ、o-PD溶液中に含まれるDAPの光吸収によって、ポリマー凝集体であるナノ構造体が得られることを示す。
o-PD溶液(0.33mM)を分光装置の測定用セルに入れ、200mW/cm2の緑色LED(波長530nm)を一定時間照射した後、各照射時間におけるo-PD溶液の吸収スペクトルを分光光度計で測定した。得られた吸光スペクトルを図5(a)に示す。上記図より、緑色LEDの照射時間が長くなる程、波長450nm付近をピークとする光吸光度スペクトルの吸光度が増加した。この吸収スペクトルの形状は、o-PDのダイマーであるDAPの吸収スペクトルの形状と一致する。すなわち、o-PD溶液の酸化によりDAPが生成し、橙色に呈色したことが分かった。
0.2mM、1mM、4mMの三種類のo-PD水溶液を上記基板上に滴下し、波長532nm、強度2mWの緑色レーザー光を集光して80秒間照射し、後方散乱光強度を測定して、その時間的変化を調べた。この結果を図7(a)に示す。図7(a)に示すように、o-PD水溶液の濃度が高いほど、後方散乱光強度が最初に極大となる時間(最初のピーク強度が得られるまでのピーク時間)が早い。
図8(a)~(f)は、1mMのo-PD水溶液に緑色レーザーを集光し、4秒ごとに反射光の画像を光学顕微鏡に取り付けたCCDカメラで順次撮影したものである。中心部の緑色のスポットがレーザー集光点からの反射光である。後方散乱光強度は図8(a)~(d)にかけて増加し、その後、図8(d)~(f)にかけて減少していることが分かる。
ここでは、後方散乱光強度の時間的変化と、形成されるナノ構造体の高さとの関係を調べた。図9(a)に本実験の測定手順を示す。
ここでは、後方散乱光強度の時間的変化のメカニズムを示すため、モデル系に対するフレネルの式を計算した。
ここでは、DAP濃度と後方散乱光強度のピーク時間の関係について調べた。図12(a)に本実験の測定手順を示す。
ここでは、酵素によってo-PDの酸化重合反応が促進されることを説明する。レーザーを基板上に集光すると、酵素による酸化重合反応によって得られるDAPの光吸収により活性酸素種が発生する。活性酸素の高い酸化力により酸化重合が進行し、集光点にポリマー凝集体であるナノ構造体が形成される。このナノ構造体がレーザー反射光強度を変化させる。
HRP溶液、過酸化水素(0~200μM)、及びo-PD溶液(1mM)をそれぞれ20μL採取してマイクロチューブ内で混合し、その混合液を基板上に20μL滴下して後方散乱光強度を測定した。以下に、HRP酵素反応によるo-PDの酸化重合反応[o-PD→DAP→Poly(OPD)(=重合体)]を示す。
o-PD溶液(0.33mM)20μL、o-PD溶液(1mM)、HRP溶液、および過酸化水素(0.2mM)の各20μLを加えた混合液20μLを基板上に滴下し、2分間レーザー光を集光し、集光点に形成されたナノ構造体のSEM観察を行なった。比較のため、o-PD溶液のみにレーザー光を集光し、同様にSEM観察を行なった。
4-1.グルコース濃度の定量
図15(a)に本実験の測定手順を示す。具体的には、グルコース水溶液(0~1mM)20μLと、GODとHRPを1:1で混合した溶液(以下、GOD/HRPと略記する。)20μLを混合し、1分間恒温放置した。o-PD溶液(1mM)20μLを加えた混合溶液から20μL採取し、基板に滴下し、後方散乱光強度を測定した。コントロールとしてGODに活性がないリボース、ラクトース水溶液(5mM)を用いて同様に後方散乱光強度の測定を行った。
図16(a)に本実験の測定手順を示す。具体的には、分光光度計の測定用セルにグルコース水溶液(0~1mM)300μLと、GOD/HRP溶液300μLを混合し、1分間恒温放置した。ここにo-PD溶液(1mM)300μLを加えて混合し、分光光度計で吸収スペクトルを測定した。図16(b)に得られた吸収スペクトルを示す。また、図16(c)に、各グルコース濃度に対するピーク吸光度をプロットしたグラフを示す。
波長473nm、532nm、633nmのレーザー光源を用いてグルコースの検出における後方散乱光強度を測定し、レーザー波長依存性を調べた。得られた後方散乱光強度の時間的変化を図17(波長473nm)、図18(波長532nm)、図19(波長633nm)に示す。更に図20に、上記の各波長における、グルコース濃度に対する後方散乱光強度のピーク時間を示す。これらの図より、波長473nmではグルコースが1μM~1mM、波長532nmでは100nM~1mM、波長633nmでは0.5~2.5mMの濃度範囲を定量できることが分かった。よって、本実験の条件下では、波長532nmの緑色レーザー光がグルコースの検出に最も適していることが分かった。
ここでは、o-PD溶液の吸収スペクトルと重合体の後方散乱光強度スペクトルとの関係を調べた。
本実験では、光増感剤の一つであるメチレンブルーによる酸化重合反応促進効果を調べた。
ここでは、本発明法によりエタノールを検出した。以下に、エタノールとAOD、o-PDとHRPの反応式を示す。
ここでは、IgG抗体を固定化したIgG抗体固定化基板を用い、これにHRP標識抗IgG抗体を結合させ、集光レーザービームによるo-PDの酸化重合反応を利用してHRP標識抗IgG抗体の検出を行った。
IgG抗体固定化基板の作製に用いられる試料溶液を以下のようにして調製した。まず、レセプターとして用いるIgG抗体(ChromPure Human IgG,whole molecule、Jackson ImmunoReserch LABORATORIES,INC.,11.8mg/mL)の濃度が100μg/mLとなるようにHEPESバッファー(10 mM、pH7.25)に溶解した。検出用抗原としてHRP標識抗IgG抗体(Rabbit polyclonal Secondary Antibody to Human IgG-H&L(HRP),pre-adsorbed、0.5mg/mL)を純水に溶解し、濃度10ng/mLの水溶液を作製した。その水溶液を純水で10倍希釈を繰り返し、濃度10fg/mL~10ng/mLの11種のHRP標識抗IgG抗体水溶液を作製した。
ここでは、基板として、一般的に用いられる市販のマイクロプレートよりもサイズの小さい顕微鏡用カバーガラスを用いた。マイクロプレートを用いたELISA法では、サンプル溶液や試薬などがそれぞれ、1ウェル当たり100μL程度必要であるが、サイズの小さい上記カバーガラスを用いれば、サンプル溶液などの容量を減らすことができる。よって、微量の被験物質を簡便且つ感度良く検出することができる。
図30(a)に、本測定法による概略図を示す。
抗IgG抗体の検出を、HRP標識抗IgG抗体との競合法によって検出した。図31(a)に、本測定法による概略図を示す。
上述したとおり、ELISA法では、被験物質に対する抗体、抗原のレセプターのほか、被験物質も固定化した基板を用いることができる。しかし、抗体などが固定化された基板表面は分子レベルでは平坦でないため、ナノ構造体が形成されにくい。
一般的にELISA法では、検出対象物質の抗体が固相化されたマイクロプレート、酵素標識抗体(二次抗体)、希釈やブロッキングなどに必要な溶液、酵素と反応して発色や蛍光性物質を産生する発色基質などが含まれた試薬キットを用いることが多い。そこで、以下では、市販のELISAキットを用いて、従来の吸光度測定法と本発明の後方散乱光強度測定法の比較実験を行った。
本実験では、被験物質としてIgG抗体を用いた。また、実験に使用するHRP標識抗IgG抗体(二次抗体)、ブロッキング溶液、洗浄液、および各工程のプロトコルは、KPL社のProtein Detector ELISA Kit,Anti-Humanを使用した。
IgG抗体(14.7mg/L)をマイクロプレート(Nunc、マキシプレート)の各ウェルに100μL滴下し、室温で3時間静置した後、洗浄して固相化した。具体的には、各ウェルにブロッキング溶液を300μL滴下し、室温で5分間静置した後、洗浄してブロッキングを行った。次いで、各濃度に希釈したHRP標識抗IgG抗体を各ウェルに100μL滴下し、室温で1時間静置した後、洗浄してIgG抗体固相基板を作製した。
上記のようにして得られた静置後の溶液を各ウェルから10μL採取し、別に用意したガラス基板に滴下した後、レーザー(波長532nm、強度8mW)を、60倍の対物レンズを用いて上記ガラス基板と上記溶液との固液界面に集光して後方散乱光強度変化を測定した。
各ウェルにおける波長405nmの吸光度を、マイクロプレートリーダー(コロナ電気、SH-1000)を用いて測定した。
これらの結果を図36(従来法)および図37(本発明法)に示す。詳細には図36は、吸光度とHRP標識抗IgG抗体の濃度との関係を示すグラフである。図37は、後方散乱光強度の最初のピークが現れた時間(図の縦軸では「ピーク時間」と記載)と、HRP標識抗IgG抗体の濃度との関係を示すグラフである。これらの図を対比すると、両者は、HRP標識抗IgG抗体濃度が100pg/mL以下の極微量レベルで明瞭な差が見られた。よって、本発明の方法を用いれば、従来の吸光度法では困難であった、例えば10pg/mL以上の極微量濃度における定量測定が可能であることが分かった。
本実験では、被験物質としてC反応性タンパク(C-reactive protein:CRP)を用いた。CRPは、体内で炎症反応や組織の破壊が起きているときに血中に現れるタンパク質であり、感染症、悪性腫瘍、心筋梗塞などの疾病の指標となる。本実験では、一般的なサンドイッチ法を利用してCRPの測定を行った。具体的には、抗体固相化マイクロプレート、HRP標識二次抗体、希釈溶液、および各工程のプロトコルは、Biocheck社のHigh Sensitivity C-reactive Protein Enzyme Immunoassay Test Kitを用いて実施した。
まず、抗CRP抗体が固相化されたマイクロプレートの各ウェルに、濃度を調整したCRP溶液を10μL滴下した。続いて、各ウェルにHRP標識二次抗体を100μL滴下し、室温で45分間静置した。
反応溶液として、2mMのo-PDと10mMの過酸化水素のクエン酸バッファー溶液との混合溶液100μLを各ウェルに滴下し、室温で1時間静置した。
反応溶液として、本実験に用いた上記Kitに付属の反応溶液[3,3’,5,5’-テトラメチルベンジジン(TMB)と過酸化水素の混合溶液]を各ウェルに100μL滴下し、室温で1時間静置した後、上記Kitに付属の反応停止液を各ウェルに100μL滴下した。各ウェルにおける波長405nmの吸光度を、マイクロプレートリーダー(コロナ電気、SH-1000)を用いて測定した。
これらの結果を図38(従来法)および図39(本発明法)に示す。詳細には図38は、吸光度とCRP濃度との関係を示すグラフである。図39は、後方散乱光強度が一度減少して、再び元の強度まで増加する時間を計測したときの時間(図の縦軸では「所定時間」と記載)と、CRP濃度との関係を示すグラフである。厳密な測定感度は使用するELISAキットに依存するが、本発明の方法を用いれば、従来の吸光度法では困難であった、例えば500pg/mL以上の極微量濃度におけるCRPの定量測定が可能であることが分かった。
本実験では、被験物質としてIgG抗体を用いると共に、微量測定のため、基板として、マイクロプレートよりサイズの小さいカバーガラスを用いた。本実験に用いたHRP標識抗IgG抗体(二次抗体)、ブロッキング溶液、洗浄液、および各工程のプロトコルは、KPL社のProtein Detector ELISA Kit,Anti-Humanを使用した。
図40を参照しながら、本実験の測定手順を説明する。まず、顕微鏡用カバーガラス17(サイズ24mm×36mm、厚さ0.12~0.17mm、MATSUNAMI)にポリスチレン溶液(溶媒キシレン、濃度10wt%)を滴下し、スピンコート法によりポリスチレン薄膜を作製した。次に、直径3mmの穴の開いたシリコンシート15(厚さ0.2mm、Asone)を密着させ、ウェルを作製した。次いで、IgG抗体25(14.7mg/L)を各ウェルに10μL滴下し、室温で3時間静置した後、洗浄した。次に、各ウェルにブロッキング溶液を10μL滴下し、室温で5分間静置した後、洗浄してブロッキングを行ってIgG抗体固相化基板を得た(以上、図40の(1)を参照)。
得られた結果を図41に示す。図41は、後方散乱光強度の最初のピークが現れた時間(図の縦軸では「ピーク時間」と記載)と、HRP標識抗IgG抗体(二次抗体)濃度との関係を示すグラフである。本実験のように抗体固相化基板と清浄な基板を重ねて、上記清浄な基板からレーザーを集光する方法を用いれば、1ng/mL以上の抗IgG抗体を再現性良く測定できることが分かった。
上述したようにo-PD溶液に緑色レーザー光を集光すると、基板上の集光点で酸化重合反応が進行し、反応により形成されるナノサイズの重合体の成長に伴って後方散乱光強度が時間的に変化する。この酸化重合反応は、HRPなどのペルオキシダーゼ酵素反応によって促進され、重合体の形成速度が増加することがSEM観察像により確認された。本発明の方法は、これらの現象を利用したものであり、100nM~1mMのグルコース濃度を感度良く定量することができた。また、グルコースの検出におけるレーザー波長依存性を調べたところ、グルコースの検出には、波長532nmの緑色レーザー光が適していることが分かった。更に、レーザー光の波長依存性とo-PD溶液の吸収スペクトル、重合体の後方散乱光強度スペクトルの関係から、本発明の検出方法では、o-PD溶液中のDAP(ダイマー)と、集光点に形成される重合体の両方による光吸収が重要であることが強く示唆された。更に本発明の方法により、エタノールを定量良く検出することができた。
2 ビームエキスパンダー
3 NDフィルター
4 メカニカルシャッター
5 倒立型顕微鏡
6 ハーフミラー
7 対物レンズ
8 ステージ
9 基板
10 ナノ構造体
11 カップラー
12 光ファイバー
13 光電子増倍管
14 データ収録用拡張ボード
15 シリコンシート
16 溶液
17 カバーガラス
21 基板
22 多孔質担体
23 抗体
24 スペーサー
25 抗体(IgG)
26 重合物質含有溶液
27 抗体固相基板
28 清浄な基板
A 抗体存在領域
B 抗体非存在領域
Claims (13)
- 被験物質から過酸化物を発生させる工程と、
前記過酸化物に、重合物質生成用酸化還元酵素、および前記重合物質生成用酸化還元酵素の基質を接触させて重合物質を得る工程と、
前記重合物質に光を照射して、照射点からの散乱光の強度の時間的変化情報を記録する工程と、
を含む被験物質の濃度測定方法。 - 前記被験物質は、酵素反応によって過酸化物を生成する物質である請求項1に記載の被験物質の濃度測定方法。
- 被験物質に、前記被験物質に対して特異的な相互作用を有する物質に重合物質生成用酸化還元酵素が修飾された修飾物質を接触させた後、過酸化物、および前記重合物質生成用酸化還元酵素の基質を接触させて重合物質を得る工程と、
前記重合物質に光を照射して、照射点からの散乱光の強度の時間的変化情報を記録する工程と、
を含むことを特徴とする被験物質の濃度測定方法。 - 前記被験物質に対して特異的な相互作用が抗原抗体反応である請求項3に記載の被験物質の濃度測定方法。
- 前記時間的変化情報が信号波形を構成しており、前記被験物質への前記光の照射開始時以降の所定の時から、前記信号波形が極値を示すまでにかかる時間を特定する工程をさらに含む請求項1~4のいずれかに記載の被験物質の濃度測定方法。
- 前記重合物質を得る工程は基体の上で行なうものである請求項1~5のいずれかに記載の被験物質の濃度測定方法。
- 前記被験物質、および前記被験物質に対して特異的な相互作用を有する物質よりなるX群物質の少なくとも一種が存在する第1の基体と、
前記被験物質、および前記被験物質に対して特異的な相互作用を有する物質よりなるX群物質の少なくとも一種が存在しない第2の基体と、
を重ね合わせ、前記第2の基体から光を照射するものである請求項6に記載の被験物質の濃度測定方法。 - 前記基体は、前記被験物質、および前記被験物質に対して特異的な相互作用を有する物質よりなるX群物質の少なくとも一種が存在するX群物質存在領域と、前記X群物質が存在しないX群物質非存在領域とを有しており、前記X群物質非存在領域に前記光を照射するものである請求項6に記載の被験物質の濃度測定方法。
- 前記基体の上に多孔質担体を設け、前記多孔質担体によって前記X群物質を固定している請求項8に記載の被験物質の濃度測定方法。
- 被験物質に光を入射できる光源と、
前記被験物質由来の重合物質からの散乱光を検知する光電変換素子と、
前記光電変換素子から出力される信号を所定時間のあいだ続けて記録する記録媒体と、を有することを特徴とする被験物質の検出装置。 - 前記被験物質由来の重合物質が光透過基体の第1面側に存在しており、
前記光透過基体の第2面側に対向しているレンズを更に有する請求項10に記載の検出装置。 - 前記被験物質由来の重合物質への前記光の照射開始時以降の所定の時から、前記記録媒体に記録されている信号波形が極値を示すまでにかかる時間を特定する計算手段をさらに有することを特徴とする請求項10または11に記載の検出装置。
- 前記光透過基体の第1面側に、前記被検物質由来の重合物質、および前記被験物質由来の重合物質に対する特異的な相互作用を有する物質よりなるX群物質の少なくとも一種が存在するX群物質存在領域と、前記X群物質が存在しないX群物質非存在領域とを有する請求項10~12のいずれかに記載の検出装置。
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US10942127B2 (en) | 2021-03-09 |
JPWO2015060269A1 (ja) | 2017-03-09 |
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US20160305889A1 (en) | 2016-10-20 |
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