MEASUREMENT APPARATUS AND ELEMENT FOR ANALYSIS

Abstract

The production amount of thiol compounds which is the product of the cyclic reaction of enzyme-labeled antibody, or the production rate thereof is measured as an adsorption rate on a gold electrode formed on an insulated gate field-effect transistor. The adsorption rate is measured by monitoring in real time the change in a potential on the gold electrode associated with the formation of a self-assembled monolayer on the gold electrode, that is, the current between a source and a drain in the insulated gate field-effect transistor. The measured adsorption rate is recorded by using a signal processing circuit and a data processing unit. Then, the amount of antigen is found from the adsorption rate. During this measuring, a high frequency voltage is applied to a reference electrode from a power supply to reduce the effect of external variations of the measurement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of an immuno analyzer according to the present invention.

FIGS. 2A and 2B are drawings showing an example of the structure of an insulated gate field-effect transistor used in the immuno analyzer according to the present invention, FIG. 2A is a cross-sectional view, and FIG. 2B is a plan view.

FIG. 3 is a drawing showing an example of the immuno analyzer according to the present invention.

FIG. 4 is a block diagram showing an example of an immuno analysis system according to the present invention.

FIG. 5 is a drawing showing a reaction flow of the immuno analysis according to the present system.

FIGS. 6A to 6H are drawings showing an effect of the high frequency superposition method according to the present invention (frequencies of the applied voltage, FIG. 6A: DC, FIG. 6B: 10 HZ, FIG. 6C: 100 Hz, FIG. 6D: 1 KHz, FIG. 6E: 10 KHz, FIG. 6F: 100 KHz, FIG. 6G: 1 MHz, and FIG. 6H: 10 MHz).

FIGS. 7A to 7H are drawings showing measurement results of thiol compound solutions having different concentrations (concentrations of the thiol compounds, FIG. 7A: 50 μM, FIG. 7B: 25 μM, FIG. 7C: 10 μM, FIG. 7D: 5 μM, FIG. 7E: 2.5 μM, FIG. 7F: 0.5 μM, and FIG. 7G: 0.1 μM).

FIG. 8 is a drawing showing the relationship between the concentration of the thiol compounds and the adsorption rate on a gold electrode according to the present invention.

FIGS. 9A to 9E are drawings showing measurement results by means of the immuno analyzer according to the present invention.

FIG. 10 is a drawing showing the relationship between the concentration in the sample solution and the adsorption rate which are measured by an apparatus according to the present invention.

FIG. 11 is a drawing showing the relationship between the concentration in the sample solution and the adsorption rate which are measured by using the apparatus according to the present invention.

FIG. 12 is a drawing showing an effect of the straight-chain polymer which is physically adsorbed on the gold electrode.

FIG. 13 is a drawing showing an effect of the straight-chain polymer which is physically adsorbed on the gold electrode.

FIGS. 14A to 14C are drawings showing an effect in a case of the combination of the gold electrode on which the straight-chain polymer is physically adsorbed and the high frequency superposition method.

FIG. 15 is a drawing showing the relationship between the frequency of the applied alternating voltage and the change (ΔV) in an interface potential.

Claims

1. A measurement apparatus comprising: a container which contains antibody to a substance to be measured;sample solution supply means which supplies, to the container, a sample solution containing the substance to be measured;enzyme-labeled antibody supply means supplying enzyme-labeled antibody in which enzyme used for producing thiol compounds in the container and the antibody to the substance to be measured are bound to each other;substrate supply means which supplying the substrate for the enzyme;a field-effect transistor;an electrode connected to a gate of the field-effect transistor with a wire and being in contact with the solution in the container;a reference electrode being in contact with the solution in the container;a power supply for applying a voltage between the electrode and the reference electrode; anda detection section for detecting the output of the field-effect transistor.

2. The measurement apparatus as set forth in claim 1, wherein the power supply applies an alternating voltage of 10 kHz or more.

3. The measurement apparatus as set forth in claim 1, wherein the antibody is immobilized on a solid phase.

4. The measurement apparatus as set forth in claim 1, wherein the antibody is immobilized on the electrode.

5. The measurement apparatus as set forth in claim 1, wherein the electrode is made of a noble metal.

6. The measurement apparatus as set forth in claim 1, wherein straight-chain polymer is physically adsorbed on the electrode.

7. The measurement apparatus as set forth in claim 1, comprising a processing section for calculating the amount of change in the output of the field-effect transistor, after the substrate supply means supplies the substrate.

8. The measurement apparatus as set forth in claim 1, comprising a processing section for calculating the initial rate of change in the output of the field-effect transistor, after the substrate supply means supplies the substrate.

9. A measurement apparatus comprising: a container into which a measurement solution containing thiol compounds is introduced;a field-effect transistor;an electrode connected to a gate of the field-effect transistor with a wire and being in contact with the measurement solution in the container;a reference electrode being in contact with the measurement solution in the container;a power supply for applying a voltage between the electrode and the reference electrode; anda detection section for detecting the output of the field-effect transistor.

10. The measurement apparatus as set forth in claim 9, wherein the power supply applies alternating voltage of 10 kHz or more.

11. The measurement apparatus as set forth in claim 9, wherein the electrode is made of a noble metal.

12. The measurement apparatus as set forth in claim 9, wherein straight-chain polymer is physically adsorbed on the electrode.

13. The measurement apparatus as set forth in claim 9, comprising a processing section for calculating the amount of change in the output of the field-effect transistor, after the measurement solution containing the thiol compounds is supplied.

14. The measurement apparatus as set forth in claim 9, comprising a processing section for calculating the initial rate of change in the output of the field-effect transistor, after the measurement solution containing the thiol compounds is supplied.

15. An element for analysis comprising: a field-effect transistor; andan electrode made of a noble metal, on the surface of which straight-chain polymer is physically adsorbed,wherein a gate of the field-effect transistor and the electrode are connected to each other with an electroconductive wire.

16. The element for analysis as set forth in claim 15, wherein the noble metal is any of gold and silver.

17. The element for analysis as set forth in claim 15, wherein the straight-chain polymer is any of dextran and polyethylene glycol.