JP2015192957A - Agitator and agitation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an agitator which can enhance quantitativity for a detection object.SOLUTION: An agitator in which an antibody 51 specifically binding an antigen 52 is fixed to an inner bottom surface, includes: magnets 3 which include a magnetic material 55 and are so disposed as to be positioned above and below a container 17 which holds a solution T containing a bead 53 onto a surface of which the antigen 54 specifically binding to the antigen 52 is fixed; and a control part 4 which preferentially and alternatively exerts a magnetic force onto the beads 53 upwards and downwards by the magnet 3 in such a manner that an impulse of a magnetic force acting on the bead 53 upwards is larger than an impulse of a magnetic force acting on the bead 53 downwards.

Description

  The present invention relates to a stirring device and a stirring method used for analysis of biological materials such as antibodies and antigens.

  An immunoassay is known in which a specific antigen or antibody associated with a disease is detected as a biomarker to quantitatively analyze the effect of disease discovery or treatment. As one of the immunoassays, the first antibody fixed on the inner wall surface of the container is reacted with the antigen in the sample solution, the unreacted substance is removed, and then the beads encapsulating the reacted antigen and the magnetic material There has been proposed a method for quantifying the amount of reaction with the second antibody labeled with. The reaction amount is quantified by detecting the light emitted from the fluorescent substance contained in the beads or counting the number of beads. As a method using such beads, there are known a method of collecting beads by attracting beads in a solution after a target reaction with a magnet, a method of rotating beads and stirring the beads in the solution, etc. (Patent) Reference 1).

  On the other hand, a technique has been proposed in which the antibody fixed on the optical disk is bound to the antigen in the sample, the antigen is labeled with the beads having the antibody, and the beads fixed on the disk are counted by scanning with an optical head. (See Patent Document 2). In general, in such a technique, a part of a bead having an antibody immobilized on its surface is non-specifically adsorbed on a substrate without reacting with a biomarker.

Special table 2010-512531 gazette Japanese Patent Laid-Open No. 5-5741

  The collision between the bead and the biomarker and the collision between the biomarker and the antibody on the substrate are unlikely to occur, and generally, the probability that the input biomarker is captured on the substrate is about 0.1 to 1%. Then, depending on the concentration of the biomarker, noise due to non-specific adsorption contained in the detection signal is also affected, making it difficult to detect the biomarker.

  Even if the solution containing the beads is stirred by rotating the magnet, a significant increase in the number of beads that specifically bind on the substrate cannot be expected. In addition, when beads are collected on the substrate surface using the technique of Patent Document 1, non-specific adsorption of the beads to the substrate increases due to the magnetic force, which may deteriorate the detection accuracy.

  In view of the above problems, an object of the present invention is to provide a stirring device and a stirring method that can improve the detection accuracy of beads that label a detection target.

  In order to achieve the above object, according to a first aspect of the present invention, a first substance (51) that specifically binds to a detection target (52) is fixed to an inner bottom surface and includes a magnetic material (55). Magnets arranged so that the second substance (54) that specifically binds to the detection target (52) is positioned above and below the container (17) holding the solution containing the particles (53) immobilized on the surface. (31, 33) and the magnet (31) so that the impulse of the magnetic force acting upward on the particle (53) is larger than the impulse of the magnetic force acting downward on the particle (53). , 33) and a control unit (4) for preferentially applying a magnetic force in an upward direction and a downward direction to the particles (53).

  In the second aspect of the present invention, the first substance that specifically binds to the detection target is fixed to the inner bottom surface, and the second substance that contains the magnetic material and specifically binds to the detection target is fixed to the surface. The product of the magnetic force acting on the particles upward and the magnetic force acting on the particles downward is applied to the particles so as to be positioned above and below the container holding the solution containing the particles. The stirring method includes a step of preferentially acting on the particles in an upward direction and a downward direction with a magnet so as to be larger.

  ADVANTAGE OF THE INVENTION According to this invention, the stirring apparatus and stirring method which can improve the detection precision of the bead which labels a detection target can be provided.

It is a typical block diagram explaining the stirring apparatus which concerns on 1st Embodiment of this invention. It is a top view explaining the board | substrate of the stirring apparatus which concerns on 1st Embodiment of this invention. It is a fragmentary perspective view explaining the board | substrate of the stirring apparatus which concerns on 1st Embodiment of this invention. (A)-(d) is an expanded sectional view of the board | substrate explaining an example of the method of fixing an antibody, an antigen, and a bead to the board | substrate of the analyzer which concerns on 1st Embodiment of this invention. It is a figure explaining operation | movement of the magnet of the stirring apparatus which concerns on 1st Embodiment of this invention. It is a typical fragmentary front view explaining operation | movement of the magnet of the stirring apparatus which concerns on 1st Embodiment of this invention. It is a typical fragmentary front view explaining operation | movement of the magnet of the stirring apparatus which concerns on 1st Embodiment of this invention. It is a typical partial front view explaining arrangement | positioning of the container and magnet used in order to show the relationship between the nonspecific adsorption | suction of a bead and a magnetic field. It is a figure which shows the relationship between the application time of a magnetic field, and the nonspecific adsorption | suction of a bead. It is a figure which shows the relationship between the distance to a magnet, and magnetic flux density. It is a figure which compares the characteristic of the biomarker density | concentration and bead count result in the analysis using the stirring apparatus which concerns on embodiment of this invention with the case where a conventional apparatus is used. It is a typical block diagram explaining the stirring apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the drive signal of the stirring apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the via voltage of the stirring apparatus which concerns on 2nd Embodiment of this invention. It is a figure explaining the drive signal of the stirring apparatus which concerns on 2nd Embodiment of this invention. It is a schematic diagram explaining the behavior of the beads in the stirring device according to the second embodiment of the present invention.

  Next, first and second embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals, and redundant description is omitted.

(First embodiment)
As shown in FIG. 1, the stirring device according to the first embodiment of the present invention includes a substrate 10, a motor 2 that rotates the substrate 10, a magnet 3 that is disposed above and below the substrate 10, and And a control unit 4 that controls the motor 2 and the magnet 3.

  The substrate 10 has a disk shape having the same dimensions as an optical disc such as a compact disc (CD), a digital versatile disc (DVD), and a Blu-ray disc (BD). The substrate 10 is made of, for example, a hydrophobic resin material such as polycarbonate resin or cycloolefin polymer used for general optical disks. The surface of the substrate 10 may be subjected to surface treatment with a thin film formation or a silane coupling agent as required.

  For example, as shown in FIG. 2, the substrate 10 has a well 15 having a plurality of through holes 16 penetrating from the upper surface to the lower surface on the upper surface. The well 15 is made of, for example, silicone rubber. The through holes 16 are arranged concentrically with the substrate 10.

  As shown in FIG. 3, the substrate 10 is formed in a spiral shape from the inner peripheral side to the outer peripheral side on the upper surface, for example, so that concave grooves 13 and convex lands 14 alternately formed in the radial direction are formed. Have. The substrate 10 and the well 15 constitute a container 17 that holds the solution T containing a sample and the like by closing the lower ends of the plurality of through holes 16 on the upper surface of the substrate 10. The upper surface of the substrate 10 and the inner side surface of the well 15 correspond to the inner bottom surface and the inner side surface of the container 17, respectively. In the embodiment of the present invention, the container 17 is constituted by the substrate 10 and the well 15, but the container is not limited to such a shape, and may be constituted integrally by the well 15, for example.

  As shown in FIG. 4, the substrate 10 has an antibody (first substance) 51 that specifically binds to an antigen 52 expressed on the surface of the biological material to be detected fixed on the surface. The antigen 52 is labeled on a bead (particle) 53 to which an antibody (second substance) 54 that specifically binds to the antigen 52 is immobilized on the surface, whereby the antigen 52 and the bead 53 are attached to the surface of the substrate 10. Are relatively fixed. Antigen 52 specifically binds to antibody 51 and antibody 54. Thus, by detecting the labeled beads (particles) 53, it is possible to quantify the concentration of the biomarker that serves as an indicator of disease or the like.

  The beads 53 are formed in a substantially spherical shape by a synthetic resin such as polystyrene containing a magnetic material 55 such as ferrite. The diameter of the beads 53 is about several tens of nm to several hundreds of nm, for example, a diameter of 200 nm.

  As shown in FIG. 4 (a), the antibody 51 is fixed to the surface of the substrate 10 in advance. The antibody 51 is bonded to the upper surface of the substrate 10 by a hydrophobic bond or a covalent bond. The antibody 51 may be fixed to the upper surface of the substrate 10 via a substance such as avidin. The antibody 51 may be fixed only to the groove 13 or only to the land 14.

  Next, as shown in FIG. 4B, a sample solution containing the antigen 52 is injected into the container 17. The antigen 52 contacts with the antibody 51 by moving in the sample solution by Brownian motion, and specifically binds to the antibody 51 by the antigen-antibody reaction.

  Next, as shown in FIG. 4C, a buffer solution containing beads 53 is injected into the container 17. The antibody 54 immobilized on the surface of the bead 53 specifically binds to the antigen 52 by the antigen-antibody reaction in the solution T containing the sample solution and the buffer solution. The beads 53 label the antigen 52 by binding to the antigen 52.

  The beads 53 are quickly gathered on the upper surface of the substrate 10 by arranging a magnet below the container 17 when the buffer solution is injected, and the reaction with the antigen 52 can be promoted. The occurrence of adsorption increases and adversely affects subsequent detection results. The stirrer according to the first embodiment is arranged so that the magnet 3 is located above and below the container 17 and is displaced, thereby reducing the occurrence of non-specific adsorption.

  The antibody 51 and the antibody 54 may be specific biological substances that specifically bind to the antigen 52, and a combination in which each binds to another site is selected. In addition, when a membrane vesicle such as an exosome in which a plurality of types of antigens 52 are expressed on the surface is to be detected, the antibody 51 and the antibody 54 are different types, so that a biological sample having two types of antigens 52 is obtained. Can be detected. Not limited to this, exosomes and the like are different from normal antigens, and a plurality of antigens, which are proteins of the same kind, are present on the surface. Therefore, the antibody 51 and the antibody 54 may be of the same type.

  As shown in FIG. 4D, the solution T injected into the container 17 is washed with a washing buffer, pure water, or the like, so that the surplus antigen 52 that does not bind to the antibody 51 and the antigen 52 do not bind. The solution containing excess beads 53 is removed. Then, after separating the well 15 from the substrate 10, the substrate 10 is optically scanned by an optical pickup and the beads 53 are detected, whereby the antigen 52 labeled on the beads 53 can be analyzed.

  The magnet 3 includes a pair of permanent magnets 31 a and 31 b that are fixed at a distance from each other and disposed above and below the container 17, and a magnet holding unit 32 that holds the permanent magnets 31 a and 31 b. The permanent magnets 31a and 31b are arranged so that the polarities on the side facing the container 17 are different from each other.

  The magnet holding portion 32 is generally formed in a C shape so as to sandwich the container 17 from the outer peripheral side of the substrate 10, and holds the permanent magnets 31a and 31b on both ends. The permanent magnets 31 a and 31 b move in the vertical direction within a set range when the magnet holding unit 32 is driven by the drive unit 43 under the control of the control unit 4.

  The control unit 4 includes a drive control unit 41 that controls the drive of the magnet 3 by controlling the drive unit 43, and a rotation control unit 42 that rotates the substrate 10 by controlling the motor 2.

  The drive control unit 41 uses the permanent magnets 31a and 31b to attach the beads 53 to the beads 53 so that the impulse of the magnetic force acting on the beads 53 in the solution T is larger than the impulse of the magnetic forces acting downward. On the other hand, a magnetic force is preferentially applied alternately upward and downward.

  The rotation control unit 42 moves the substrate 10 to the motor 2 so that the stirring of the permanent magnets 31a and 31b by the magnetic force of the permanent magnets 31a and 31b in one container 17 is completed. Rotate.

  An example of the operation of the agitation apparatus according to the first embodiment in which the drive control unit 41 agitates the solution T injected into the container 17 by moving the magnet 3 to the drive unit 43 will be described with reference to FIG. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the upward moving distance of the magnet 3.

At time t _1, as shown in FIG. 6, the magnet 3 is located at the lowest point with respect to the container 17 by movement range set. At this time, the magnetic force of the upper permanent magnet 31a preferentially acts on the beads 53 in the solution T and moves upward. From time t ₁ to time t ₂ , the drive control unit 41 causes the drive unit 43 to move the magnet 3 upward.

In time t _2, the as shown in FIG. 7, the magnet 3 is located at the highest point with respect to the container 17 by movement range set. In time t _2, the beads 53 in the solution T, by the magnetic force of the lower permanent magnet 31b acts most preferentially, moves downward.

Here, the movement termination speed U of the beads 53 is expressed as shown in Expression (1).
U = F / (3πμdp) (1)
In the formula (1), F represents the force applied to the beads 53, dp represents the diameter of the beads 53, and μ represents the magnetic permeability of the magnetic material 55. The force F is expressed as in equation (2).
F = (1-Nd) μ ₀ μr Vp (H · ∇H) (2)
In Equation (2), H is the magnetic field generated by the permanent magnets 31a and 31b, Nd is the demagnetizing factor, Vp is the volume of the magnetic material 55 included, dp is the diameter of the beads 53, and μ is the magnetic permeability of the magnetic material.

  The force F is the sum of the attractive force applied to the beads 53 by the magnetic field and the reaction force proportional to the product of the viscous resistance of the solution T and the velocity of the beads 53 that are received while moving in the solution T. The beads 53 move at a constant speed when the attractive force and the reaction force of the force F are balanced. However, as described above, the beads 53 are nano-sized and sufficiently satisfy the low Reynolds number condition. If the density of the beads 53 is considered to be close to 1, it can be considered that the beads 53 move at a constant speed in the solution T simultaneously with the application of the magnetic field.

  However, as the distance between the bead 53 and the permanent magnets 31a and 31b becomes shorter, the attractive force by the permanent magnets 31a and 31b becomes larger, so that the bead 53 is accelerated. When the beads 53 are accelerated by the attractive force of the lower permanent magnet 31b and the collision between the substrate 10 and the beads 53 increases, non-specific adsorption of the beads 53 on the substrate 10 increases.

To reduce non-specific adsorption of the beads 53, the magnet 3, under the control of the drive control unit 41, immediately after the closest above the permanent magnet 31a at time t _2, the until time t _3, moves downward . Profile relating to movement of the magnet 3 from time t ₂ to time t _3, equation (1), equation (2), the moving distance of the magnet can be determined by the size, etc. of the container 17. Between the time t ₂ to time t _3, the beads 53, attraction by the upper permanent magnet 31a acts preferentially.

At time t _3, the magnet 3 is located at an intermediate position where the distance to the container 17 and the upper permanent magnet 31a and the lower permanent magnet 31b are equal, respectively. At this time, the beads 53 in the solution T do not move by magnetic force because the attractive force by the permanent magnet 31a balances the attractive force by the permanent magnet 31b.

From time t ₃ to time t ₄ , the magnet 3 is held at the intermediate position by the drive unit 43. Between the time _{t 3} to time _{t 4,} the beads 53 in the solution T is diffusion due to Brownian motion occurs in accordance with equation (3).
D = KT / (3πηdp) (3)

In Expression (3), D is the moving distance of the beads 53, T is the temperature, K is the Boltzmann constant, η is the viscosity constant of the solution T, and dp is the diameter of the beads 53. From time t ₃ to time t ₄ , the diffusion of the beads 53 promotes the antigen-antibody reaction between the antigen 52, the antibody 51, and the antibody 54. The antigen-antibody reaction in the solution T is saturated, for example, when the container 17 is maintained at 37 ° C. for 2 minutes or more. From time t ₄ to time t ₅ , the drive control unit 41 causes the drive unit 43 to lower the magnet 3. Magnet 3 At time t _5, located at the lowest point with respect to the container 17 by movement range set.

  Here, the beads 53 are distributed in the solution T. Therefore, it is conceivable that some beads 53 reach the substrate 10 and the attractive force by the permanent magnet 31b continues to act. Then, a part of the beads 53 are directly bonded to the antibody 51 of the substrate 10 by van der Waals force or the like without using a biological material having the antigen 52 as a biomarker.

Therefore, the drive control unit 41 holds the magnet 3 in a state where the upper permanent magnet 31 a is closest to the container 17 at time t _{5 to} t ₆ . It is desirable that the distance between the permanent magnet 31a and the liquid surface of the solution T is a distance at which a force F larger than the non-specific adsorption force of the beads 53 and smaller than the specific adsorption force is applied by the permanent magnet 31a.

-Relationship between non-specific adsorption and magnetic field-
As shown in FIG. 8, the inventors arrange the magnet 31 below the container 17 into which the solution T has been injected so that the distance D between the substrate 10 and the magnet 31 forming the bottom surface of the container 17 is the distance D. The time during which the magnetic field was applied to the solution T by the magnet 31 was changed, and the beads 53 adsorbed nonspecifically to the substrate 10 on which the antibody 51 was immobilized were detected. As shown in FIG. 9, the detection amount when the distance D is 1 mm is larger than the detection amount when the distance D is 5 mm. Further, when the distance D is 1 mm and 5 mm, the detected amount of the beads 53 increases as the application time of the magnetic field becomes longer.

  As shown in FIG. 10, the magnetic flux density increases as the distance from the magnet 31 is shorter, regardless of the type of the magnet 31. The detection result of FIG. 9 is a result when the magnet 31 is N45t6 of FIG. N45t6 means a neodymium magnet having a material of N45 and a thickness of 6 mm. The neodymium magnet used in the example shown in FIG. 10 has a cylindrical shape and a diameter of 6 mm. When the magnet 31 is N45t6, the magnetic flux density when the distance D is 1 mm is 4000 G, the magnetic flux density when the distance D is 5 mm is about 720 G, and the difference is about 5.5 times.

  From the above, it can be seen that the more the magnetic force is applied, the more the number of non-specifically adsorbed beads 53 increases in a short time. Further, it can be seen that non-specific adsorption of the beads 53 increases with the integration of the magnetic force acting on the beads 53 and the action time. The beads 53 non-specifically adsorbed on the substrate 10 are detected as noise in the detection of the biomarker and become a factor that deteriorates the detection accuracy.

During the period from time t ₁ to time t _{6 in} FIG. 5, the drive unit 43 generates an impulse of magnetic force acting upward on the beads 53 by the permanent magnets 31 a and 31 b according to the control of the drive control unit 41. However, the magnet 3 is moved so that it may become larger than the impulse of the magnetic force which acts downward. The drive unit 43 repeats the movement of the magnet 3 in one cycle from time t ₁ to time t ₆ , and causes the solution T to be applied by preferentially applying a magnetic force to the beads 53 in the upward and downward directions. Stir.

  The stirrer according to the first embodiment of the present invention reduces the nonspecific adsorption of the beads 53 by applying a magnetic force to the beads 53 as described above, and also increases the stroke distance of the beads 53 to increase the biomarker. The collision probability can be increased. Therefore, when the substrate 10 is optically scanned, in the detection signal, the noise N due to the beads 53 non-specifically adsorbed on the substrate 10 is reduced, and the signal S due to the beads 53 labeled with the biomarker is increased. Thus, according to the stirring apparatus which concerns on 1st Embodiment, SN ratio can be improved and the detection precision of the bead 53 which labels a detection target can be improved.

-Comparative example-
FIG. 11 is a comparative example of the result P1 obtained by labeling the biomarker with the stirrer according to the first embodiment and counting the beads 53 and the result P2 obtained by labeling the biomarker with the conventional method and counting the beads 53. Will be explained. The horizontal axis represents the concentration of the biomarker (antigen 52) to be detected, and the vertical axis represents the counting result of detecting the beads 53.

  For results P1 and P2, ideally, if the biomarker content is 0, the counting result should also be 0. However, due to non-specific adsorption, even if the biomarker concentration is 0, beads 53 fixed on the surface of the substrate 10 by non-specific adsorption are counted as noise.

  It can be seen that the noise level Q1 of the result P1 is reduced with respect to the noise level Q2 of the result P2. Furthermore, in the result P1, the detected amount of the biomarker at the same concentration is increased as compared with the result P2. Therefore, according to the stirring apparatus which concerns on 1st Embodiment, it turns out that the SN ratio of the detection signal of the bead 53 labeled with the biomarker can be improved.

  In the curves P1 and P2, the contact points (intersections) between the lower limit of error and the background noise levels Q1 and Q2 of the curves P1 and P2 are referred to as minimum detection sensitivities R1 and R2, respectively. The minimum detection sensitivity R1 is improved compared to the minimum detection sensitivity R2, and it can be seen that the sensitivity of biomarker detection is improved. Therefore, it can be seen that according to the stirring device according to the first embodiment, the detection sensitivity of diseases and the like can be improved in the analysis of biological substances and the like.

(Second Embodiment)
As shown in FIG. 12, the stirring device according to the second embodiment of the present invention includes a pair of electromagnets 33a and 33b disposed above and below the container 17 in place of the permanent magnets 31a and 31b. Different from one embodiment. Other configurations, operations, and effects that are not described in the second embodiment are substantially the same as those in the first embodiment and are omitted because they overlap.

  The electromagnets 33a and 33b are respectively held by a magnet holder 32 (see FIG. 1) and are spatially fixed so that the distances to the solution T injected into the container 17 are equal to each other. The electromagnets 33a and 33b are each composed of a core and a coil wound around the core. The electromagnets 33a and 33b generate different magnetic forces when different driving signals are input to both ends of each coil and the respective cores are magnetized.

The stirrer according to the second embodiment includes a drive unit 45 that drives the electromagnets 33 a and 33 b under the control of the drive control unit 41. The drive unit 45 inputs drive signals I ₁ and I ₂ to both ends of each coil of the electromagnets 33a and 33b in accordance with the control of the drive control unit 41, respectively.

The drive signals I ₁ and I ₂ are alternating currents that are sinusoidal waves having the same period as shown in FIG. 13, for example. In this case, the driving signals I ₁ and I ₂ are out of phase with each other by 90 ° or 270 °. Thus, at time t ₁₁ the force is maximized below the electromagnet 33b, the magnetic force of the upper electromagnet 33a becomes zero. That is, the beads 53 in the solution T move downward at time t ₁₁ . At time t ₁₂ the force of the upper electromagnet 33a is maximized, the magnetic force of the lower electromagnet 33b is zero. In other words, the beads 53 in the solution T at time t ₁₂ is moved upward.

Thus, the drive signals I ₁ and I ₂ are set so that the beads 53 move up and down in vibration. Therefore, the bead 53 has a longer stroke distance and can increase the probability of colliding with the biomarker.

Further, as shown in FIG. 14, for example, the drive signals I ₁ and I ₂ input to the electromagnets 33a and 33b are supplied with DC bias voltages v _B1 and v by the drive unit 45 according to the control of the drive control unit 41. _B2 is added to each. From time t ₂₁ to time t ₂₂ , the drive signal I ₂ is shifted in the positive direction by adding the bias voltage v _{B2 as} shown in FIG. Therefore, from time t ₂₁ to time t ₂₂ , the beads 53 in the solution T move downward while vibrating up and down as shown in FIG.

Between the time t ₂₂ in FIG. 14 to time t _23, the bias voltage v _B1, v _B2 becomes 0, the beads 53 in the solution T vibrates up and down in place. Between the time t ₂₃ to the time t _24, the drive signal I ₁ is shifted in the positive direction by the bias voltage v _B2 is added. Thus, between the time t ₂₃ to the time t _24, the beads 53 in the solution T is moves upward while oscillating up and down.

As described above, the bias voltages v _B1 and v _B2 are alternately and repeatedly added to the drive signals I ₁ and I ₂ , so that the beads 53 that vibrate up and down are alternately given priority in the upward and downward directions. Magnetic force can be applied.

The time from the time t ₂₃ to the bias voltage v _B1 is added to the time t _24, longer than the time from time t ₂₁ to the bias voltage v _B2 is added to the time t _22. That is, the drive control unit 41 uses the electromagnets 33a and 33b to move the electromagnets 33a and 33b so that the impulse of the magnetic force acting on the beads 53 is larger than the impulse of the magnetic force acting on the beads 53. Driven.

  The stirrer according to the second embodiment reduces the nonspecific adsorption of the beads 53 on the substrate 10 by applying a magnetic force to the beads 53 as described above, and increases the stroke distance of the beads 53 to increase the biomarker. The collision probability can be increased. Therefore, when the substrate 10 is optically scanned, in the detection signal, the noise N due to the beads 53 non-specifically adsorbed on the substrate 10 is reduced, and the signal S due to the beads 53 labeled with the biomarker is increased. According to the stirrer according to the first embodiment, the SN ratio can be improved, and the detection accuracy of the beads 53 that label the detection target can be improved.

  For example, it is assumed that the beads 53 are sucked by an electromagnet disposed only below the container 17 to cause nonspecific adsorption on the substrate 10. Thereafter, if the polarity of the electromagnet is reversed, a magnetic field opposite to the magnetization direction of the magnetic material 55 of the non-specifically adsorbed bead 53 is applied, so that a repulsive force is generated on the bead 53 with respect to the electromagnet. . However, as described above, the beads 53 used as an immune reaction label have a diameter of about several tens to 200 nm, and the size of the magnetic material 55 to be included is several tens of nm. The behavior of the magnetic material 55 of several tens of nanometers at room temperature is different from that of a general ferromagnet, and is caused by thermal disturbance rather than the exchange energy that maintains the anisotropy of the magnetic moment in the molecule due to spin-orbit interaction. It is in a “super paramagnetic” state that is more influential. Therefore, the beads 53 have no anisotropy and the magnetization easily rotates. That is, the magnetic material 55 included in the non-specifically adsorbed beads 53 undergoes magnetization reversal at the moment when the magnetic field is reversed, and as a result, repulsive force does not work and only attractive force continues to be applied.

(Other embodiments)
As described above, the present invention has been described according to the first and second embodiments. However, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the first embodiment already described, the magnet 3 is not limited to the configuration in which the permanent magnets 31 a and 31 b are held by the magnet holding portion 32. The magnet 3 may be a C-shaped permanent magnet having opposite polarities at both ends.

  In the first and second embodiments already described, the combination of the biological material that is the detection target and the specific biological material that specifically binds to the detection target is the combination of the antigen 52, the antibody 51, and the antibody 54. It is not limited to a combination. The combination that specifically binds may be, for example, a combination of a ligand and a receptor (enzyme protein, lectin, hormone, etc.), a combination of nucleic acids having mutually complementary base sequences, and the like.

In the second embodiment already described, the drive signals I ₁ and I ₂ input to the electromagnets 33a and 33b are not limited to sinusoidal alternating currents, and may be currents such as rectangular waves.

  In addition, of course, the present invention includes various embodiments that are not described here, such as a configuration in which the first and second embodiments are applied to each other. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

2 Motor 3 Magnet 4 Control unit 10 Substrate 13 Groove 14 Land 15 Well 17 Container 31a, 31b Permanent magnet 32 Magnet holding unit 33a, 33b Electromagnet 41 Drive control unit 42 Rotation control unit 43, 45 Drive unit 51, 54 Antibody (first material)
52 Antigen (second substance)
53 beads

Claims (5)

A container that holds a solution containing particles in which a first substance that specifically binds to a detection target is fixed to the inner bottom surface, encloses a magnetic material, and contains a second substance that specifically binds to the detection target. Magnets arranged to be above and below
The magnet causes the particle to move upward and downward with respect to the particle so that the impulse of the magnetic force acting upward on the particle is greater than the impulse of the magnetic force acting downward on the particle. A stirring device comprising: a control unit that alternately and preferentially applies a magnetic force. The magnets are a pair of permanent magnets fixed at a distance between each other and disposed above and below the container,
The stirring device according to claim 1, wherein the control unit causes a magnetic force to act on the particles by moving a position in a vertical direction of the pair of permanent magnets. The magnet is a pair of electromagnets disposed above and below the container,
2. The stirring device according to claim 1, wherein the control unit causes the particles to exert a magnetic force by driving the pair of electromagnets with two different signals.   The stirring device according to claim 3, wherein the control unit uses the two signals as alternating currents that are out of phase with each other. A container that holds a solution containing particles in which a first substance that specifically binds to a detection target is fixed to the inner bottom surface, encloses a magnetic material, and contains a second substance that specifically binds to the detection target. So that the magnetic force of the magnetic force acting on the particles in the upward direction is larger than the impulse of magnetic force acting on the particles in the downward direction. A step of causing the magnetic force to preferentially act on the particles alternately and upwardly by the magnet.

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