JPH10307104A - SPR sensor - Google Patents

Abstract

(57) Abstract: A surface plasmon resonance can be easily measured without using an immobilizing substance for immobilizing a substance to be measured on a metal thin film surface of a sensor. An electrode (14) is provided on an outer surface of a cell (2) at a position facing a metal thin film (6). A DC power supply (16) is provided between the metal thin film (6) and the metal thin film (6) side is a positive pole. Connected. In the cell 2, a metal thin film 6 is provided.
An electric field is generated between the electrode and the electrode 14, and the negatively-charged substance to be measured contained in the sample liquid in the cell 2 is attracted in the direction of the metal thin film 6 by Coulomb force. Light source device 1
The incident light 8a condensed in a wedge shape from 0 and incident on the interface with the metal thin film 6 is caused by a specific substance in the incident light 8a when the substance to be measured in the sample liquid in the cell 2 approaches the metal thin film 6 by an electric field. Light at an angle is absorbed, and the absorbed incident angle in the reflected light 8b detected by the detector 12 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SPR (Surface Plasmon Resonance) sensor expected to be used in the fields of life science and clinical examination.

[0002]

2. Description of the Related Art An SPR sensor is a sensor utilizing surface plasmon resonance, in which a metal thin film is formed in a glass cell in which a sample solution is contained or flows, and the glass of the cell and the sample in the cell are formed from the back side of the metal thin film. Light is incident under the condition of total reflection at the interface with the liquid, the reflected light is detected, and the incident angle at which the intensity decreases in the reflected light is measured.

In the SPR sensor, a light having a specific incident angle out of light incident on the interface between the cell glass and the sample liquid under the condition of total reflection is absorbed. The incident angle of the light receiving the absorption depends on the refractive index of the sample liquid existing in the cell. The SPR sensor measures the incident angle at which the light is absorbed, and measures the refractive index of the sample solution, and thus the concentration of the substance in the sample solution. The change in the incident angle reflects the change in the amount of the substance in the sample liquid in the cell.

[0004] Since surface plasmon resonance is a phenomenon on the surface of a metal, it is affected only by a substance very close to the surface of the metal film. Therefore, in order to fix the substance to be measured to the metal thin film of the sensor, an immobilizing substance such as dextran is provided in the sensor portion. For a detailed description of the SPR sensor, see, for example, “Protein Nucleic Acid Enzyme”, November, Vol.
Pages 7 to 2984 and pages 3005 to 3011 (1992).

[0005]

In the conventional SPR sensor, an immobilizing substance such as dextran is provided in order to immobilize the substance to be measured on the sensor portion. However, when the substance to be measured does not conform to the immobilizing substance. Has a problem that measurement cannot be performed. Therefore, there is a problem in that an appropriate immobilized substance must be found according to the substance to be measured.
It is known that the surface plasmon resonance phenomenon occurs even when the substance to be measured does not necessarily adhere to the metal thin film as long as it is closer than the wavelength of light. Therefore, an object of the present invention is to make it possible to easily measure surface plasmon resonance without using an immobilizing substance for fixing a substance to be measured on a metal thin film surface of a sensor.

[0006]

An SPR sensor according to the present invention comprises means for applying an electric field or a magnetic field to a substance to be measured in a sample solution in a cell to generate a force for moving the substance in the direction of the metal thin film in the sensor portion. ing. Many molecules in biological samples are often negatively charged. When an electric field is applied to such molecules, a Coulomb force is generated and the molecules can be brought closer to the metal thin film. In the case of a flow cell,
When such a charged molecule is moving, a magnetic field acts to generate a Lawrence force, so that the molecule can be brought closer to the metal thin film.

[0007]

FIG. 1A is a schematic sectional view of a first embodiment. One surface of the glass cell 2 is integrally provided with a prism 4 on the outside thereof, and a metal thin film 6 is adhered to the inside of the cell on the surface on which the prism 4 is provided. A sample solution is flowed or stored in the cell 2.

Outside the cell 2, there is provided a light source device 10 for making incident light 8 a of a laser beam condensed in a wedge shape incident on the prism 4. The incident angle θ of the incident light 8a is set to an angle at which total reflection occurs at the interface between the glass surface of the prism 4 and the sample liquid in the cell 2. A detector 12 is provided to receive the reflected light 8b due to the incident light 8a. The detector 12 is an array type detector that can simultaneously detect lights having different reflection angles.

An electrode 14 is provided on the outer surface of the cell 2 at a position facing the metal thin film 6.
4, a DC power supply 16 is connected so that the metal thin film 6 side becomes a positive pole. An electric field is generated between the metal thin film 6 and the electrode 14 in the cell 2, and a substance having a negative charge contained in the sample liquid in the cell 2 is attracted in the direction of the metal thin film 6 by Coulomb force.

The incident light 8a condensed in a wedge shape from the light source device 10 and incident on the interface with the metal thin film 6 is incident when the substance to be measured in the sample liquid in the cell 2 approaches the metal thin film 6 by an electric field. The light at a specific angle in 8a is absorbed, and the absorbed incident angle in the reflected light 8b detected by the detector 12 is obtained.

The cell 2 may be a cell in which a sample liquid is stored, or a flow cell in which a sample liquid flows.
Now, consider the case where cell 2 is a flow cell.
A change in the incident angle absorbed by surface plasmon resonance is called a resonance signal, and a change in 10 ^-4 degrees is 1 RU (reso).
nance unit). When a resonance signal is measured by the detector 12 using the flow cell, a signal as shown in FIG. 1B is obtained. Therefore, this sensor can be used for a detector such as a liquid chromatograph.

FIG. 2 shows a second embodiment utilizing a Lorentz force by applying a magnetic field to bring a substance to be measured in a sample solution close to a metal thin film of a sensor. If the cell 2 is a flow cell, and the sample liquid containing the negatively charged substance to be measured flows in the left direction, the current will flow in the right direction on the contrary, and the magnetic field acts in the direction perpendicular to the plane of the paper. As a result, the Lorentz force acts on the charged particles to move them in the direction of the metal thin film 6. The structure of the cell 2 is the same as that shown in FIG. 1A, and includes a light source device 10 and an array-type detector 12 for measuring an incident angle at which the cell 2 is absorbed by surface plasmon resonance.

[0013]

According to the present invention, an SPR sensor has conventionally required any immobilized support layer to attach a substance to be measured to a metal thin film of the sensor. According to the present invention, such an immobilized support layer is not required. become. Therefore, all charged substances to be measured can be measured without making the compatibility between the substance to be measured and the immobilized support layer a problem. When a flow cell is used as a cell, it can be used as a detector of a flow type analyzer such as a liquid chromatograph.

[Brief description of the drawings]

FIGS. 1A and 1B show a first embodiment, in which FIG. 1A is a schematic sectional view, and FIG. 1B is a waveform chart showing an example of continuous measurement.

FIG. 2 is a schematic sectional view showing a second embodiment.

[Explanation of symbols]

 2 cell 4 prism 6 metal thin film 8a incident light 8b reflected light 10 light source device 12 detector 14 electrode 16 power supply device

Claims (1)

[Claims] 1. A metal thin film is formed in a glass cell in which a sample liquid is contained or flows, and light is incident from the back side of the metal thin film under the condition of total reflection at the interface between the glass of the cell and the sample liquid in the cell. The reflected light is detected, and the incident angle at which the intensity is reduced in the reflected light is measured. In the SPR sensor, the force to move the substance to be measured in the sample liquid in the cell toward the metal thin film. An SPR sensor, comprising: means for applying an electric field or a magnetic field for generating an electric field.