JP7217187B2 - Surface acoustic wave sensor and antigen concentration detection method using surface acoustic wave sensor - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to techniques for detecting the concentration of antigens in specimens such as blood.

A surface acoustic wave sensor is used to detect the concentration of an antigen in a sample such as blood (see, for example, Patent Document 1). In other words, changes in weight or viscoelasticity based on the amount of antigen in the collected sample before and after introduction of the sample are detected as changes in the propagation amplitude or propagation phase of the surface acoustic wave. A surface acoustic wave sensor comprises interdigitated electrodes and a detection area. Comb electrodes are formed on the piezoelectric substrate to transmit, receive or reflect surface acoustic waves. A sensing region is formed on the piezoelectric substrate and introduced with an analyte.

JP 2017-009492 A

A prior art method for detecting the concentration of an antigen in a specimen is shown in FIG. First, the sample containing the antigen AG and the secondary antibody AB2 of the sandwich assay method is thoroughly mixed and reacted in advance. Here, the secondary antibody AB2 is a monoclonal antibody and has only one recognition site for the antigen AG. As shown in the upper left column of FIG. 1, when the amount of antigen is less than the amount of secondary antibody, there is antigen AG that has reacted with secondary antibody AB2, but there is no antigen AG that has not reacted with secondary antibody AB2. As shown in the upper right column of FIG. 1, when the amount of antigen is greater than the amount of secondary antibody, there is antigen AG that has reacted with secondary antibody AB2, and there is also antigen AG that has not reacted with secondary antibody AB2.

Next, the specimen sufficiently mixed and reacted in advance is dropped onto the detection area 111 on which the primary antibody AB1 for the sandwich assay method is immobilized. Here, the primary antibody AB1 is also a monoclonal antibody and has only one recognition site for the antigen AG. However, the primary antibody AB1 and the secondary antibody AB2 differ in the recognition site of the antigen AG. As shown in the left middle column of FIG. 1, when the amount of antigen is less than the amount of secondary antibody, antigen AG reacted with secondary antibody AB2 binds to primary antibody AB1, and the system as a whole is in equilibrium. As shown in the right middle column of FIG. 1, when the amount of antigen is greater than the amount of the secondary antibody, the antigen AG that reacted with the secondary antibody AB2 also binds to the primary antibody AB1, and the antigen that has not reacted with the secondary antibody AB2 AG also binds primary antibody AB1 and the whole system comes to equilibrium.

Next, the concentration of antigen AG in the sample is detected based on the output signal of the channel. Here, the output signal of the channel is the change in propagation amplitude or propagation phase of the surface acoustic wave before and after the introduction of the specimen. Then, prior to antigen concentration detection, after fixing the concentration of the secondary antibody AB2 in the sample, the output signal of the channel is measured for various known concentrations of the antigen AG in the sample. For various other concentrations of antigen AG, the output signal of the channel is interpolated and the calibration curve of output signal/antigen concentration shown at the bottom of FIG. 1 is stored.

As shown in the lower left part of FIG. 1, when the amount of antigen is less than the amount of secondary antibody, the output signal of the channel increases monotonically as the total concentration of antigen AG in the specimen increases. Then, since the output signal of the channel is measured to be _SN , the total concentration of the antigen AG in the sample is correctly detected to be _CN based on the calibration curve of output signal/antigen concentration.

As shown on the lower right side of FIG. 1, when the amount of antigen is greater than the amount of secondary antibody, the output signal of the channel changes from increasing to decreasing as the total concentration of antigen AG in the specimen increases. This is because the antigen AG that has not reacted with the secondary antibody AB2 is smaller in mass and size than the antigen AG that has reacted with the secondary antibody AB2, and is called the hook phenomenon. Then, although the output signal of the channel is measured to be S _H (>S _N ), based on the output signal/antigen concentration calibration curve, the total concentration of antigen AG in the sample is less than the hook state C _HT ( >C _N , true value) or unhooked C _HF (>C _N , false value) or not detected correctly.

If the specimen containing the antigen AG and the secondary antibody AB2 has not been sufficiently mixed and reacted in advance, the amount of the antigen should not only be greater than the amount of the secondary antibody, but also less than the amount of the secondary antibody. However, there is an antigen AG that has not reacted with the secondary antibody AB2. Then, even when the output signal of the channel is originally _SN or _SH , the total concentration of the antigen AG in the sample cannot be detected correctly because the measurement will vary. Therefore, sufficient pre-mixing reaction of the specimen is required, but the degree of pre-mixing reaction of the specimen is unknown.

Therefore, in order to solve the above problems, the present disclosure uses a surface acoustic wave sensor and a sandwich assay method to detect the concentration of an antigen in a specimen such as blood, and the amount of antigen is more than the amount of secondary antibody. The objective is to correctly detect the total concentration of antigen in a sample even when it is high, and to detect the hook phenomenon or anomalies of insufficient mixing even when the premixing reaction is insufficient.

In order to solve the above problems, a channel on which a secondary antibody is immobilized is provided in addition to the channel on which the primary antibody is immobilized. Then, the antigen that has not reacted with the secondary antibody in advance can bind to the secondary antibody on the channel, but the antigen that has reacted with the secondary antibody in advance cannot bind to the secondary antibody on the channel. Therefore, only antigens that have not reacted with the secondary antibody can be detected in advance.

Specifically, the present disclosure provides a first detection region having a primary antibody immobilized thereon for a sandwich assay, and a first interdigitated electrode that transmits and receives or transmits and reflects surface acoustic waves. A second channel comprising a channel, a second detection area immobilized with a secondary antibody for sandwich assay, and a second interdigitated electrode for transmitting and receiving or transmitting and reflecting surface acoustic waves. A surface acoustic wave sensor characterized by

According to this configuration, the unbound antigen detection section and the antigen concentration detection section, which will be described later, are used to correctly detect the total concentration of the antigen in the specimen even when the amount of the antigen is greater than the amount of the secondary antibody, Hook phenomena or under-mixing anomalies can be detected even during an insufficient pre-mixing reaction.

Further, in the present disclosure, based on the output signal of the second channel, the secondary The surface acoustic wave sensor further comprises an unbound antigen detection section that detects whether or not the antigen that is not bound to the antibody is present.

Further, the present disclosure is an antigen concentration detection method using a surface acoustic wave sensor, wherein the surface acoustic wave sensor includes a first detection region on which a primary antibody of sandwich assay method is immobilized, and a surface acoustic wave. and a first interdigitated electrode that receives or transmits and reflects, a second detection region on which a secondary antibody of the sandwich assay is immobilized, and a surface acoustic wave that transmits and receives or transmits and reflects a second channel comprising a reflective second comb-shaped electrode; and determining whether or not the antigen not bound to the secondary antibody is present in the sample based on the output signal of the second channel. and a detecting unbound antigen detection procedure for detecting antigen concentration using a surface acoustic wave sensor.

According to these configurations, even when the amount of antigen is larger than the amount of the secondary antibody, and even when the pre-mixing reaction is insufficient, the hook phenomenon or the abnormality of insufficient mixing can be detected.

Further, according to the present disclosure, when the unbound antigen detection unit detects the presence of the antigen that is not bound to the secondary antibody in the specimen, based on the output signal of the second channel, or detecting the concentration of the antigen in the specimen based on the output signal of the second channel and the output signal of the first channel in which the specimen is also dropped in the first detection region, and detecting the non-binding antigen detection unit; detects that the antigen not bound to the secondary antibody is absent in the specimen, based on the output signal of the first channel in which the specimen is also dropped onto the first detection region, and and an antigen concentration detection unit for detecting the concentration of the antigen in the specimen considering that the output signal of the second channel is approximately zero.

According to this configuration, even when the amount of antigen is greater than the amount of secondary antibody, the total concentration of antigen in the sample can be detected correctly.

Further, according to the present disclosure, when the unbound antigen detection unit detects that the antigen that is not bound to the secondary antibody is present in the specimen, the output signal of the second channel and the second detection The concentration of the antigen in the sample is determined based on the output signal of the first channel in which the sample, from which the antigen has been removed in the region and has been moved from the second detection region, is dropped onto the first detection region. When the unbound antigen detection unit detects that the antigen not bound to the secondary antibody does not exist in the specimen, the second detection does not cause an antibody-antigen reaction in the second detection region. An antigen concentration detection unit that detects the concentration of the antigen in the specimen based on the output signal of the first channel in which the specimen moved from the area is dropped onto the first detection area. is a surface acoustic wave sensor.

According to this configuration, even when the amount of antigen is larger than the amount of secondary antibody, and even when the pre-mixing reaction is insufficient, the total concentration of antigen in the sample can be detected correctly.

Thus, the present disclosure is useful in utilizing surface acoustic wave sensors and sandwich assays to detect the concentration of antigen in a specimen such as blood, even when the amount of antigen is greater than the amount of secondary antibody. , it is possible to correctly detect the total concentration of antigen in the specimen and to detect hook phenomena or undermixing abnormalities even during insufficient premixing reactions.

FIG. 1 shows a prior art method for detecting the concentration of an antigen in a sample. 1 is a diagram showing a configuration of a surface acoustic wave sensor according to first and second embodiments of the present disclosure; FIG. FIG. 4 is a diagram showing a procedure for detecting the concentration of an antigen in a specimen according to the first embodiment of the present disclosure; FIG. FIG. 2 is a diagram showing a method for detecting the concentration of antigens in a specimen according to the first embodiment of the present disclosure; FIG. FIG. 4 is a diagram showing detection results of antigen concentration in a specimen according to the first embodiment of the present disclosure; FIG. 10 is a diagram showing a procedure for detecting the concentration of an antigen in a sample according to the second embodiment of the present disclosure; FIG. FIG. 10 is a diagram showing a method for detecting the concentration of antigens in a specimen according to the second embodiment of the present disclosure;

Embodiments of the present disclosure will be described with reference to the accompanying drawings. The embodiments described below are examples of implementing the present disclosure, and the present disclosure is not limited to the following embodiments.

FIG. 2 shows the configuration of the surface acoustic wave sensor according to the first embodiment of the present disclosure. The surface acoustic wave sensor S is composed of a surface acoustic wave sensor body 1 and an antigen concentration detection device 2 . The surface acoustic wave sensor main body 1 is composed of a first channel 11 , a second channel 12 and a third channel 13 . The first channel 11 consists of a first detection region 111 and a first comb electrode 112 . The second channel 12 consists of a second detection region 121 and a second comb electrode 122 . The third channel 13 is composed of a third detection region 131 and a third comb electrode 132 . The antigen concentration detection device 2 is composed of an unbound antigen detection section 21 and an antigen concentration detection section 22 .

The first detection region 111 is immobilized with the primary antibody AB1 for the sandwich assay method. The first comb electrodes 112 transmit and receive or transmit and reflect surface acoustic waves. Second detection region 121 is immobilized with secondary antibody AB2 for sandwich assay method. The second comb-shaped electrode 122 transmits and receives or transmits and reflects surface acoustic waves. A blocking membrane that does not react with the antigen AG is immobilized on the third detection region 131 for reference. The third comb electrode 132 transmits and receives or transmits and reflects surface acoustic waves for reference. The unbound antigen detection unit 21 measures the phase and amplitude of the output signals of the first channel 11, the second channel 12 and the third channel 13 by switching the switches in the previous stage. The antigen concentration detector 22 stores calibration curves of the output signal/antigen concentration of the first channel 11 and the second channel 12 (see the lower part of FIG. 4 or FIG. 7).

3 and 4 show the procedure/method for detecting the concentration of the antigen in the specimen according to the first embodiment of the present disclosure. First, a specimen containing antigen AG and secondary antibody AB2 is sufficiently mixed and reacted in advance (step S1). As shown in the upper left column of FIG. 4, when the amount of antigen is less than the amount of secondary antibody, antigen AG reacted with secondary antibody AB2 exists, but antigen AG unreacted with secondary antibody AB2 does not exist. As shown in the upper right column of FIG. 4, when the amount of antigen is greater than the amount of secondary antibody, there is antigen AG that has reacted with secondary antibody AB2, and there is also antigen AG that has not reacted with secondary antibody AB2.

Next, the sample sufficiently mixed and reacted in advance is dropped onto the first, second and third detection regions 111, 121 and 131 (step S2). As shown in the left middle column of FIG. 4, when the antigen amount is less than the secondary antibody amount, the antigen AG that has reacted with the secondary antibody AB2 in advance does not bind to the primary antibody AB1 on the first detection area 111. It is possible, but it cannot bind to the secondary antibody AB2 on the second detection area 121 . The whole system then reaches equilibrium. As shown in the right middle column of FIG. 4, when the antigen amount is larger than the secondary antibody amount, the antigen AG that has reacted with the secondary antibody AB2 in advance does not bind to the primary antibody AB1 on the first detection area 111. It is possible, but it cannot bind to the secondary antibody AB2 on the second detection area 121 . On the other hand, the antigen AG that has not previously reacted with the secondary antibody AB2 can bind to both the primary antibody AB1 on the first detection area 111 and the secondary antibody AB2 on the second detection area 121. be. The whole system then reaches equilibrium.

Next, based on the output signals of the second and third channels 12 and 13, the unbound antigen detection section 21 detects whether or not the antigen AG not bound to the secondary antibody AB2 is present in the specimen (step S3). Here, the output signal of the second channel 12 is the change in propagation amplitude or propagation phase of the surface acoustic wave before and after the introduction of the specimen. Then, by using the output signal of the third channel 13 as a reference, after removing the influence of disturbance such as the viscoelasticity of the specimen and temperature change, the secondary antibody AB2 on the second detection area 121 and the binding to it Extract only the effect of the antigen AG. The output signal of the third channel 13 may be used as a reference, but it is not essential.

As shown later on the lower left side of FIG. 4, when the amount of antigen is less than the amount of secondary antibody, the output signal of second channel 12 is nearly zero even if the total concentration of antigen AG in the sample increases. Since the output signal of the second channel 12 is measured to be S _N2 (≈0), it is detected that there is no antigen AG not bound to the secondary antibody AB2 in the sample, and the hook phenomenon does not occur. is determined not to exist.

As shown later on the lower right side of FIG. 4, when the amount of antigen is greater than the amount of secondary antibody, the output signal of second channel 12 increases monotonically as the total concentration of antigen AG in the sample increases. Then, since the output signal of the second channel 12 is measured as S _H2 (≠0), it is detected that the antigen AG not bound to the secondary antibody AB2 is present in the sample, and the hook phenomenon occurs. is determined.

Next, when the unbound antigen detection unit 21 detects that the antigen AG not bound to the secondary antibody AB2 is present in the sample (YES in step S4), the antigen concentration detection unit 22 detects second and third Based on the output signals of channels 12 and 13 or based on the output signals of first to third channels 11 to 13, the concentration of antigen AG in the sample is detected (step S5). On the other hand, when the unbound antigen detection unit 21 detects that the antigen AG not bound to the secondary antibody AB2 does not exist in the specimen (NO in step S4), the antigen concentration detection unit 22 detects the first and third Based on the output signals of channels 11 and 13 and considering that the output signal of second channel 12 is approximately 0, the concentration of antigen AG in the specimen is detected (step S6).

Here, the output signal of the first channel 11 is the change in propagation amplitude or propagation phase of the surface acoustic wave before and after the introduction of the specimen. Then, by using the output signal of the third channel 13 as a reference, after removing the influence of disturbance such as the viscoelasticity of the specimen and temperature change, the primary antibody AB1 on the first detection area 111 and the binding to it Only the effects of secondary antibody AB2 and antigen AG are extracted. The output signal of the third channel 13 may be used as a reference, but it is not essential.

Then, prior to antigen concentration detection, after fixing the concentration of the secondary antibody AB2 in the specimen, the output signals of the first and second channels 11 and 12 for various known concentrations of the antigen AG in the specimen and interpolate the output signals of the first and second channels 11 and 12 for various other concentrations of the antigen AG in the specimen, and obtain the output signal/antigen concentration calibration curve shown in the lower part of FIG. Remember.

As shown in the lower left part of FIG. 4, when the amount of antigen is less than the amount of secondary antibody, the output signal of first channel 11 increases monotonically as the total concentration of antigen AG in the specimen increases. On the other hand, even if the total concentration of antigen AG in the sample increases, the output signal of second channel 12 is almost zero.

4, the output signal of the first channel 11 was measured to be S ₁₁ (>0) and the output signal of the second channel 12 was measured to be S ₂₁ (≈0). be done. Therefore, based on the output signal/antigen concentration calibration curve of the first channel 11, the total concentration of the antigen AG in the specimen is correctly detected as C _N1 (>0).

For the black triangles on the bottom left of FIG. 4, the output signal of the first channel 11 is measured to be S ₁₂ (>S ₁₁ ) and the output signal of the second channel 12 is S ₂₁ (≈0). is measured as Therefore, based on the output signal/antigen concentration calibration curve of the first channel 11, the total concentration of the antigen AG in the sample is detected to be C _N2 (>C _N1 ) or C _H (>C _N2 ). , based on the fact that the output signal of the second channel 12 is S ₂₁ (≈0), the total concentration of the antigen AG in the sample is C _N2 (<C _H ) instead of C _H (>C _N2 ). Correctly detected.

As shown on the lower right side of FIG. 4, when the amount of antigen is greater than the amount of secondary antibody, the output signal of second channel 12 monotonically increases as the total concentration of antigen AG in the specimen increases. On the other hand, as the total concentration of the antigen AG in the specimen increases, the output signal of the first channel 11 changes from increasing to decreasing.

For the black squares on the bottom right of FIG. 4, the output signal of the first channel 11 is measured to be S ₁₂ (>S ₁₁ ) and the output signal of the second channel 12 is S ₂₂ (>0). is measured as Therefore, based on the output signal/antigen concentration calibration curve of the second channel 12, the total concentration of the antigen AG in the specimen is correctly detected as C _H (>C _N2 ). Alternatively, based on the output signal/antigen concentration calibration curve of the first channel 11, the total concentration of the antigen AG in the sample is detected to be C _N2 (>C _N1 ) or C _H (>C _N2 ). , based on the fact that the output signal of the second channel 12 is S ₂₂ (>0), the total concentration of the antigen AG in the specimen is C _H (>C _N2 ) instead of C _N2 (<C _H ). Correctly detected.

If the specimen containing the antigen AG and the secondary antibody AB2 has not been sufficiently mixed and reacted in advance, the amount of the antigen should not only be greater than the amount of the secondary antibody, but also less than the amount of the secondary antibody. However, there is an antigen AG that has not reacted with the secondary antibody AB2. However, during an insufficient pre-mixing reaction, an under-mixing anomaly can be detected based on the output signal of the second channel 12 being S ₂₂ (>0). Then, when sufficient premixing is performed, an abnormality in the hook phenomenon can be detected based on the fact that the output signal of the second channel 12 is S ₂₂ (>0). Furthermore, when the pre-mixing is sufficient, it can be detected that there is no hook phenomenon and insufficient mixing based on the fact that the output signal of the second channel 12 is S ₂₁ (≈0).

FIG. 5 shows the detection result of the antigen concentration in the specimen according to the first embodiment of the present disclosure. As the ratio of the secondary antibody amount to the antigen amount decreases, the output signal of the first channel 11 decreases, the output signal of the second channel 12 increases, and the output signal of the third channel 13 is almost zero. I understand. However, the output signal of the second channel 12 decreases as the ratio of secondary antibody to antigen decreases from 1.3 to 0.4. This is because the secondary antibody amount on the second detection area 121 is less than the secondary antibody AB2 and the unreacted antigen amount (output signal saturation).

Thus, even when the amount of antigen is greater than the amount of secondary antibody, the occurrence of the hook phenomenon can be detected and the total concentration of antigen AG in the sample can be detected correctly. And even during an insufficient pre-mixing reaction, it is possible to detect the hook phenomenon or anomalies of insufficient mixing.

6 and 7 show the procedure/method for detecting the concentration of the antigen in the specimen according to the second embodiment of the present disclosure. The configuration of the surface acoustic wave sensor S of the second embodiment is the same as that of the surface acoustic wave sensor S of the first embodiment. Steps S11 to S14 in FIG. 6 are the same as steps S1 to S4 in FIG. However, in step S<b>12 of FIG. 6 , the specimen sufficiently mixed and reacted in advance is dropped onto the second and third detection regions 121 and 131 . The upper left column, upper right column, upper left middle column and upper right middle column in FIG. 7 are the same as the lower left upper column, upper right column, left middle column and lower right middle column in FIG.

Next, when the unbound antigen detection unit 21 detects the presence of the antigen AG not bound to the secondary antibody AB2 in the sample (YES in step S14), the antigen concentration detection unit 22 detects the presence of the second detection region. The specimen from which the antigen AG has been removed in 121 is moved from the second detection area 121 to the first detection area 111 (step S15). Then, the concentration of the antigen AG in the specimen is detected based on the output signals of the first to third channels 11 to 13 (step S16). The output signal of the third channel 13 may be used as a reference, but it is not essential.

On the other hand, when the unbound antigen detection unit 21 detects that the sample does not contain the antigen AG that is not bound to the secondary antibody AB2 (NO in step S14), the antigen concentration detection unit 22 detects the second detection region. In 121, the specimen with no antibody-antigen reaction is moved from the second detection area 121 to the first detection area 111 (step S17). Then, the concentration of the antigen AG in the sample is detected based on the output signals of the first and third channels 11 and 13 (step S18). The output signal of the third channel 13 may be used as a reference, but it is not essential.

Here, in order to move the sample from the second detection region 121 to the first detection region 111, a moisturizing member on the second detection region 121 and a moisture absorbing member on the first detection region 111 may be used (Patent See Document 1. When pure water or the like is dripped onto the moisturizing member, the specimen moves to the moisture absorbing member.

In order to remove the antigen AG in the second detection region 121, the amount of secondary antibody on the second detection region 121 may be increased, or a micro stirrer on the second detection region 121 may be used. , the binding reaction barrier between the secondary antibody AB2 on the second detection area 121 and the antigen AG may be lowered.

As shown in the lower left middle column of FIG. 7, when the antigen amount is smaller than the secondary antibody amount, the antigen AG that has reacted with the secondary antibody AB2 in advance is the primary antibody AB1 on the first detection area 111. can be combined with In addition, there is no antigen AG that has not reacted with the secondary antibody AB2 in advance. The whole system then reaches equilibrium. As shown in the lower right middle column of FIG. 7, when the antigen amount is larger than the secondary antibody amount, the antigen AG that has reacted with the secondary antibody AB2 in advance is detected by the primary antibody AB1 on the first detection area 111. can be combined with The antigen AG that has not reacted with the secondary antibody AB2 has already been removed in advance. The whole system then reaches equilibrium.

Here, the following processing is executed prior to antigen concentration detection. First, after fixing the concentration of the secondary antibody AB2 in the specimen to 0, the output signal of the second channel 12 is measured for various known concentrations of the antigen AG in the specimen, and the antigen AG in the specimen is measured. , the output signal of the second channel 12 is interpolated for various other concentrations of . Next, the secondary antibody AB2 in the sample and the antigen AG are allowed to react in a one-to-one ratio, and then various known concentrations of the complex of the secondary antibody AB2 and the antigen AG in the sample are tested. The output signal of one channel 11 is measured and the output signal of the first channel 11 is interpolated for various other concentrations of complexes of secondary antibody AB2 and antigen AG in the specimen. As a result, the output signal/antigen concentration calibration curves shown in the lower left and lower right columns of FIG. 7 are stored.

As shown in the lower left and lower right columns of FIG. 7, the output signal of the second channel 12 monotonously increases as the concentration of the secondary antibody AB2 and unreacted antigen AG in the sample increases. On the other hand, the output signal of the first channel 11 monotonously increases as the concentration of the antigen AG reacted with the secondary antibody AB2 in the specimen increases. Here, the output signal of the first channel 11 monotonically increases faster than the output signal of the second channel 12 . This is because the antigen AG reacted with the secondary antibody AB2 is larger in mass and size than the antigen AG unreacted with the secondary antibody AB2.

As shown in the lower left column of FIG. 7, when the amount of antigen is less than the amount of secondary antibody, the output signal of the first channel 11 is measured as _SN1 . Therefore, the concentration of the antigen AG reacted with the secondary antibody _AB2 in the sample is correctly detected as CN1. On the other hand, since the output signal of the second channel 12 is measured to be S _N2 (≈0), based on the output signal/antigen concentration calibration curve, the secondary antibody AB2 in the specimen and the unreacted antigen AG is correctly detected as 0. Therefore, the total concentration of antigen AG in the specimen is _CN1 .

As shown in the lower right column of FIG. 7, when the amount of antigen is greater than the amount of secondary antibody, the output signal of the first channel 11 is measured as _SH1 , so the output signal/antigen concentration calibration curve is Based on this, the concentration of the antigen AG that reacted with the secondary antibody _AB2 in the sample is correctly detected as CH1. On the other hand, since the output signal of the second channel 12 is measured to be S _H2 (≠0), based on the output signal/antigen concentration calibration curve, the secondary antibody AB2 in the specimen and the unreacted antigen AG is correctly detected to be _CH2 . Therefore, the total concentration of antigen AG in the specimen is C _H1 +C _H2 .

If the specimen containing the antigen AG and the secondary antibody AB2 has not been sufficiently mixed and reacted in advance, the amount of the antigen should not only be greater than the amount of the secondary antibody, but also less than the amount of the secondary antibody. However, since the secondary antibody AB2 and unreacted antigen AG are present, the hook phenomenon occurs. However, the output signal/antigen concentration calibration curves shown in the lower left and lower right columns of FIG. 7 can be used in the same way as in the case of a sufficient premixing reaction, even with an insufficient premixing reaction. This is because the output signal/antigen concentration calibration curves shown in the lower left and lower right columns of FIG. This is because the concentration of the antigen AG or the concentration of the antigen AG that has not reacted with the secondary antibody AB2 in the sample is plotted on the horizontal axis.

Thus, even when the amount of antigen is greater than the amount of secondary antibody, the occurrence of the hook phenomenon can be detected and the total concentration of antigen AG in the sample can be detected correctly. Then, even when the pre-mixing reaction is insufficient, the occurrence of the hook phenomenon can be detected, and the total concentration of the antigen AG in the sample can be detected correctly.

The surface acoustic wave sensor and antigen concentration detection method of the present disclosure can be applied to the use of detecting the concentration of antigen in a specimen such as blood using a sandwich assay method.

S: Surface acoustic wave sensor AB1: Primary antibody AB2: Secondary antibody AG: Antigen 1: Surface acoustic wave sensor body 2: Antigen concentration detector 11: First channel 12: Second channel 13: Third channel 21: Non Bound antigen detection unit 22: antigen concentration detection unit 111: detection region, first detection region 112: first comb-shaped electrode 121: second detection region 122: second comb-shaped electrode 131: third detection region 132: third comb-shaped electrode

Claims (5)

a first channel comprising a first detection area immobilized with a primary antibody for sandwich assay and a first interdigitated electrode for transmitting and receiving or transmitting and reflecting surface acoustic waves;
a second channel comprising a second detection region immobilized with a secondary antibody of the sandwich assay method and a second comb-shaped electrode that transmits and receives or transmits and reflects surface acoustic waves;
A surface acoustic wave sensor comprising: Based on the output signal of the second channel, the sample that contains the antigen and the secondary antibody, is mixed and reacted in advance, and is dropped onto the second detection region does not bind to the secondary antibody. an unbound antigen detector that detects whether the antigen is present;
The surface acoustic wave sensor of claim 1, further comprising: When the unbound antigen detection unit detects the presence of the antigen that is not bound to the secondary antibody in the specimen, based on the output signal of the second channel, or the output of the second channel detecting the concentration of the antigen in the specimen based on the signal and the output signal of the first channel in which the specimen is also dropped into the first detection region;
When the unbound antigen detection unit detects that the antigen not bound to the secondary antibody does not exist in the specimen, the output of the first channel in which the specimen is also dropped into the first detection region an antigen concentration detection unit that detects the concentration of the antigen in the specimen based on the signal and considering that the output signal of the second channel is approximately zero;
3. The surface acoustic wave sensor of claim 2, further comprising: When the unbound antigen detection unit detects the presence of the antigen that is not bound to the secondary antibody in the specimen, the output signal of the second channel and the removal of the antigen by the second detection region detecting the concentration of the antigen in the specimen based on the output signal of the first channel in which the specimen that has been removed from the second detection area and dropped onto the first detection area;
When the non-binding antigen detection section detects that the antigen that is not bound to the secondary antibody does not exist in the specimen, the antibody-antigen reaction does not occur in the second detection area and the antigen moves from the second detection area. an antigen concentration detection unit that detects the concentration of the antigen in the sample based on the output signal of the first channel in which the sample is dropped onto the first detection region;
3. The surface acoustic wave sensor of claim 2, further comprising: An antigen concentration detection method using a surface acoustic wave sensor, comprising:
The surface acoustic wave sensor is
a first channel comprising a first detection area immobilized with a primary antibody for sandwich assay and a first interdigitated electrode for transmitting and receiving or transmitting and reflecting surface acoustic waves;
a second channel comprising a second detection region immobilized with a secondary antibody of the sandwich assay method and a second comb-shaped electrode that transmits and receives or transmits and reflects surface acoustic waves;
with
The antigen concentration detection method comprises:
A sample mixing procedure for pre-mixing and reacting a sample containing an antigen and the secondary antibody;
A sample dropping procedure for dropping the sample mixed and reacted in advance onto the second detection area;
an unbound antigen detection procedure for detecting whether or not the antigen not bound to the secondary antibody is present in the specimen based on the output signal of the second channel;
An antigen concentration detection method using a surface acoustic wave sensor, comprising in order:

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