Liquid recovery device

Abstract

This liquid recovery device comprises: a magnetic rod that attracts magnetic beads; a first container that accommodates an extraction liquid for extracting a nucleic acid, and the magnetic beads, which are capable of adsorbing and releasing the nucleic acid; and a recovery region that is for recovering the extraction liquid, as a residual liquid, from the magnetic rod while the magnetic beads are magnetically adhered thereto. The liquid recovery device extracts the nucleic acid in the first container, and then brings the magnetic rod, which is in a condition in which the magnetic beads are magnetically adhered thereto, into contact with the recovery region, and recovers the residual liquid.

Description

Liquid Recovery Device

[0001] The present invention relates to a liquid recovery device, and more particularly to a device used for extracting nucleic acids from a sample containing nucleic acids and magnetic beads.

[0002] In recent years, information obtained through nucleic acid analysis, such as genome testing using next-generation sequencing (NGS) systems, has been utilized in various fields, including medicine, clinical testing, the pharmaceutical industry, and the food industry. For this nucleic acid analysis, nucleic acid extraction from various biological samples, such as blood, tissues, and cultured cells, is an essential pretreatment step.

[0003] Nucleic acid extraction methods generally do not use harmful organic solvents such as phenol or chloroform, but rather rely on the property of nucleic acids to bind to silica in the presence of a chaotropic agent or on the property of nucleic acids to bind to silica in the presence of an organic solvent. These methods include nucleic acid extraction methods using a nucleic acid capture chip incorporating a silica-containing solid phase as a nucleic acid capture carrier, and methods using magnetic beads (nucleic acid capture carriers) whose surfaces are coated with silica. These methods include a step of binding nucleic acids to the nucleic acid capture carrier, a washing step to remove impurities, and an extraction step of eluting nucleic acids from the nucleic acid capture carrier using an extraction solution (also called an eluent or elution solution).

[0004] In the method using magnetic beads, the magnetic beads are separated from a mixture of the nucleic acid extract and magnetic beads using a magnet, and the extract is recovered. One example is a method in which the extract containing the magnetic beads is drawn into a dispensing tip, the magnetic beads are retained in the dispensing tip using a magnet, and only the extract is ejected from the dispensing tip. Another example is a method in which a rod-shaped magnet (which may be covered) is inserted into the extract containing the magnetic beads to recover the magnetic beads from the extract.

[0005] Patent Document 1 describes a method for efficiently collecting magnetic beads, in which the magnetic beads are first collected on the wall of a container and then recovered using a magnetic rod.

[0006] Patent document 2 describes a technology in which collection of magnetic material from a magnetic-containing liquid is performed not on the container side where the sample is stored, but by a dispenser that aspirates and dispenses the magnetic-containing liquid.

[0007] Patent Document 3 describes a technology in which the shape of the cover of the magnetic body that collects magnetic beads is designed to cover the outside of the reaction vessel in addition to covering the magnetic body, thereby preventing the scattering of liquid and aerosol.

[0008] U.S. Patent No. 6,020,211, Japanese Patent Application Laid-Open No. 11-262678, International Publication No. 2014 / 007074, pamphlet

[0009] Tests using nucleic acids from biological samples are usually performed in the following order: "collection of the biological sample," "extraction of nucleic acids from the biological sample," and "nucleic acid analysis." The present invention solves the problem of "extraction of nucleic acids from the biological sample."

[0010] First, we will explain the nucleic acid extraction method using magnetic beads and a magnetic bar. In the final step of nucleic acid extraction, a rod-shaped magnet called a magnetic bar is inserted into an extract solution containing magnetic beads, causing the magnetic beads in the solution to gather on the magnetic bar. This is called "magnetic collection" in the present invention. In this case, it is desirable for the magnetic bar to be covered with a cover made of a material such as plastic, in which case the magnetic beads will gather on the magnetic bar via the cover. When the magnetic bar and cover are removed from the container, the magnetic beads and the extract solution are separated, leaving the nucleic acid extract solution in the container. This nucleic acid extract solution is then used for "nucleic acid analysis" such as NGS or dPCR.

[0011] In recent years, in order to improve the measurement sensitivity of nucleic acid analysis, it has become necessary to extract as much nucleic acid as possible and use as much of that nucleic acid in nucleic acid analysis. To achieve this, it is necessary to extract a smaller volume of nucleic acid from a larger amount of biological sample than before. Increasing the amount of biological sample allows for a larger amount of nucleic acid to be obtained. Furthermore, since each nucleic acid analysis method has a limit to the amount of nucleic acid extract used in nucleic acid analysis such as NGS after nucleic acid extraction, extracting with a smaller volume of liquid has the effect of concentrating the nucleic acid extract and allowing more nucleic acid to be used in nucleic acid analysis than before.

[0012] As the amount of biological sample to be processed increases, the amount of magnetic beads, which are nucleic acid capture carriers, must also be increased accordingly. After magnetic collection, when the magnetic bar and cover are removed from the container, not only the magnetic beads but also a small amount of extract solution adheres to the magnetic bar or cover, resulting in a loss of extract solution. In this invention, the extract solution adhering to the magnetic bar or cover is referred to as the "residual liquid." In particular, we found that when the number of magnetic beads increases, the volume of magnetic beads collected on the magnetic bar and cover increases, and at the same time, the amount of extract solution lost (i.e., the residual liquid) also increases. Furthermore, in small-volume extractions, the absolute volume of extract solution is small, so the impact of loss is relatively greater.

[0013] An object of the present invention is to provide an extract recovery device that can suppress loss during separation of magnetic beads and extract in a nucleic acid extraction method using magnetic beads and a magnetic rod.

[0014] An example of a liquid recovery device according to the present invention is a liquid recovery device comprising: a magnetic bar that adsorbs magnetic beads; a first container that contains an extract for extracting nucleic acids and magnetic beads capable of adsorbing and releasing the nucleic acids; and a recovery area for recovering the extract as residual liquid from the magnetic bar that has adsorbed the magnetic beads, wherein the liquid recovery device extracts the nucleic acids in the first container, and then brings the magnetic bar that has adsorbed the magnetic beads into contact with the recovery area to recover the residual liquid.

[0015] With the liquid recovery device according to the present invention, even if residual liquid remains on the magnetic rod or cover to which magnetic beads are attached, the residual liquid can be recovered by contact. This allows more residual liquid to be recovered than in the past, so more nucleic acids can be extracted and more nucleic acids can be used for nucleic acid analysis.

[0016] 1 is a diagram illustrating a nucleic acid extraction method using magnetic beads 1 and a magnetic rod 2 according to the prior art.

[0023] FIG. 1 is a result of an experimental study of the effect of the amount of magnetic beads 1 in the extraction process on the amount of recovered extract in the prior art. A schematic diagram of the extraction process when a normal amount of magnetic beads 1 is used in the experiment of FIG. 2. A schematic diagram of the extraction process when a five-fold amount of magnetic beads 1 is used in the experiment of FIG. 2. An example of a liquid recovery device comprising a first container 10 and an empty second container 11 according to embodiment 1 of the present invention. Experimental results verifying the effect of additional recovery in embodiment 1. An operation diagram of embodiment 2 when the magnetic rod 2 with residual liquid 9 attached thereto is brought into contact with the second container 11. An example of a liquid recovery device according to embodiment 3, comprising a contact portion 13 for recovering residual liquid 9 in a portion of the first container 10. A specific example of replacing the magnetic rod. A specific example of adjusting the distance between the magnetic rod and the magnetic beads.

[0017] A nucleic acid extraction method using a conventional liquid recovery device will be described below, and a part of the conventional technology described below is also used in the examples of the present invention.

[0018] 1 illustrates a conventional nucleic acid extraction method using magnetic beads 1 and a magnetic rod 2. The magnetic rod 2 may be provided with a cover 3 that covers the magnetic rod 2. The magnetic rod 2 has the function of collecting the magnetic beads 1. When the cover 3 is not provided, the magnetic beads 1 are directly accumulated on the magnetic rod 2. When the magnetic rod 2 is covered with the cover 3, the magnetic beads 1 are accumulated on the magnetic rod 2 via the cover 3.

[0019] Hereinafter, in this specification, even when simply referring to the magnetic bar 2, it may mean the combination of the magnetic bar 2 and the cover 3.

[0020] The cover 3 serves to separate the magnetic rod 2 from the magnetic beads 1 when the magnetic beads 1 attracted to the magnetic rod 2 are dispersed in a solution (e.g., a binding solution 4, a washing solution 5, or an extraction solution 6), and to protect the magnetic rod 2.

[0021] The nucleic acid extraction method using magnetic beads 1 and magnetic rod 2 involves the following operations: - "agitation" of binding solution 4, washing solution 5, or extraction solution 6 by moving cover 3 up and down - "magnetic collection" by inserting magnetic rod 2 into binding solution 4, washing solution 5, or extraction solution 6 containing magnetic beads 1, causing magnetic beads 1 to accumulate on magnetic rod 2 - "separation" of magnetic beads 1 from binding solution 4, washing solution 5, or extraction solution 6 by removing magnetic rod 2 and cover 3 from container 7 containing binding solution 4, washing solution 5, or extraction solution 6 after magnetic collection - "diffusion" of magnetic beads 1 into binding solution 4, washing solution 5, or extraction solution 6 to be used next by moving separated magnetic beads 1 into binding solution 4, washing solution 5, or extraction solution 6 to be used next, and then removing magnetic rod 2 while leaving cover 3 in place Nucleic acid extraction is performed by combining and repeating these functions.

[0022] As shown in FIG. 1, the nucleic acid extraction process is roughly divided into the following three steps.

[0023] Step 11) Binding: For a biological sample containing nucleic acid, a binding solution 4 (consisting of components such as a buffer that solubilizes proteins in the sample, a binding buffer containing a chaotropic salt, and magnetic beads 1 that adsorb nucleic acid in the presence of a chaotropic salt) is stirred to bind the nucleic acid in the sample to the magnetic beads 1.

[0024] A more detailed example of step 11) "binding" is as follows: Step 11a) The cover 3 is moved up and down to "agitate" the liquid and bind the nucleic acid to the magnetic beads 1. Step 11b) The magnetic rod 2 is inserted into the cover 3 and the magnetic beads are accumulated on the magnetic rod 2 (cover 3). ("magnetic collection") Step 11c) The magnetic rod 2 (cover 3) is removed from the container 7 to "separate" the magnetic beads 1 from the solution. Step 11d) The magnetic beads 1 are moved to the washing solution 5, the magnetic rod 2 is removed, and the magnetic beads 1 are "diffused" into the liquid.

[0025] Step 12) Washing: As in step 11), the magnetic beads 1 are stirred, attracted, and separated. For example, the nucleic acid-bound magnetic beads 1 are mixed and stirred with the washing solution 5, and the magnetic beads 1 are separated from the washing solution 5 to remove contaminants such as proteins from the biological sample. In some cases, washing may be repeated multiple times.

[0026] Step 13) Extraction: The magnetic beads 1 and the extract solution 6 are mixed and stirred, whereby the nucleic acids bound to the magnetic beads 1 are eluted into the extract solution 6. The magnetic beads 1 are accumulated on the magnetic rod 2 and separated from the extract solution 6.

[0027] A more detailed example of step 13) "extraction" is as follows: Step 13a) Transfer the magnetic beads 1 to the extraction liquid. Step 13b) As in step 11), stir and collect the magnetic beads 1. Step 13c) Separate the magnetic beads from the extraction liquid.

[0028] Figure 2 shows the results of an experimental study of the effect of the amount of magnetic beads used in the extraction process on the amount of extract recovered in the conventional technology. Extraction was performed using 30 μL of extract under two conditions: the normal amount of magnetic beads and five times the amount. The amount of extract separated from the magnetic beads and recovered in a container was measured. Each condition was tested with n=2.

[0029] As a result, it was found that the amount of recovered liquid was less than the normal amount when the amount of magnetic beads was five times as much. The reason for this is that when the magnetic beads and the extract were separated, the extract adhered to the magnetic rod along with the magnetic beads, resulting in loss.

[0030] The extract attached to the magnetic rod together with the magnetic beads is referred to herein as the residual liquid.

[0031] 3A and 3B are schematic diagrams showing the difference in the amount of recovered extract depending on the amount of magnetic beads 1 used in this experiment.

[0032] FIG. 3A shows the extraction process when a normal amount of magnetic beads 1 is used.

[0033] Step 31) Stir the extract 6 and the magnetic beads 1. When the mixture of the extract 6 and the magnetic beads 1 is stirred with the cover 3, the nucleic acids bound to the magnetic beads 1 are eluted into the extract 6.

[0034] Step 32) Next, when the magnetic rod 2 is inserted into the cover 3, the magnetic beads 1 are attracted to the magnetic rod 2 via the cover 3.

[0035] Step 33) Finally, the magnetic beads 1 are separated from the extract 6. The magnetic bar 2 and cover 3 are removed from the container 7, leaving the extract 8 in the container 7.

[0036] The cover 3 may not be necessary during the magnetic collection and separation steps. The amount of extract 8 remaining in the container 7 is the amount of extracted liquid recovered. During separation, a portion of the extract adheres to the magnetic rod 2 or the cover 3 along with the magnetic beads 1 and is lost as residual extract liquid 9.

[0037] Figure 3B shows the case where five times the normal amount of magnetic beads 1 was used. The operations of steps 31) to 33) are the same as in Figure 3A.

[0038] In step 33), magnetic beads 1 are piled up on the surface of the magnetic bar 2 or cover 3, and the extract enters the gaps between them, forming residual extract 9. In this way, the amount of residual extract 9 is greater than when using a normal amount of magnetic beads 1, and as a result, the amount of recovered extract 8 is reduced compared to when using a normal amount of magnetic beads 1.

[0039] Hereinafter, an example of a liquid recovery device for additionally recovering residual liquid 9 will be described in an embodiment of the present invention. Description of parts common to the prior art described using Figures 1, 2, 3A, and 3B may be omitted.

[0040] <Embodiment 1> Fig. 4 shows a liquid recovery device according to embodiment 1 of the present invention. Fig. 4 shows an example of a device including a first container 10 containing magnetic beads 1 and an extract 6, and an empty second container 11.

[0041] The liquid recovery device includes a magnetic rod 2 that adsorbs magnetic beads 1. It may further include a cover 3 that covers the magnetic rod 2. The cover 3 is detachable from the magnetic rod 2. The extraction liquid 6 is an extraction liquid that extracts nucleic acids from a biological sample. The magnetic beads 1 are capable of adsorbing and releasing nucleic acids.

[0042] The second container 11 is for collecting the residual liquid 9, and functions as a collection area for collecting the extract as the residual liquid 9 from the magnetic rod 2 that has adsorbed the magnetic beads 1. That is, in this embodiment, the collection area is the second container 11 separate from the first container 10.

[0043] The second container 11 has, for example, a container shape, but may also be flat, and may have any shape as long as it is an area for recovering the residual liquid 9.

[0044] Step 41) The liquid recovery device inserts the cover 3 with the magnetic rod 2 inserted into the extract 6 in the first container 10 to magnetically collect the magnetic beads 1. In this manner, with the cover 3 attached to the magnetic rod 2, the magnetic rod 2 adsorbs the magnetic beads 1 via the cover 3. After the nucleic acids are eluted from the magnetic beads 1 into the extract 6 in the first container 10, the magnetic rod 2 magnetically collects the magnetic beads 1 in the extract 6. In this manner, the liquid recovery device extracts nucleic acids in the first container 10.

[0045] Step 42) The cover 3 with the magnetic rod 2 inserted therein is removed from the first container 10 to separate the magnetic beads 1 and the extract 6. When the magnetic rod 2 is removed from the first container 10, the magnetic beads 1 and the extract 8 are separated, and the extract 8 that can be recovered remains in the first container 10. In this way, the nucleic acids are released from the magnetic beads 1 by adding the magnetic rod 2 to the extract 6 and stirring it.

[0046] This extract 8 is also called the “first recovery liquid.” At this time, the extract, together with the magnetic beads 1, adheres to the magnetic rod 2 as residual liquid 9.

[0047] Step 43) Next, the magnetic bar 2 and the cover 3 are brought into contact with the second container 11. That is, the magnetic bar 2 with the residual liquid 9 attached thereto is brought into contact with the second container 11.

[0048] Step 44) Finally, when the magnetic rod 2 is removed from the second container 11, the extract (residual liquid 9) adhering to the magnetic rod 2 or the cover 3 moves to the second container 11 and can be recovered as additional recovery liquid 12.

[0049] In this way, the liquid recovery device brings the magnetic rod 2, which has adsorbed the magnetic beads 1, into contact with the second container 11 (for example, its inside; more specifically, the inner wall or bottom surface), and recovers the residual liquid 9 as additional recovered liquid 12.

[0050] Although not shown, a third or subsequent container may be provided, and additional collection may be performed in the same manner.

[0051] The additional recovery liquid 12 is equivalent to the extract liquid 8 (first recovery liquid). The liquid recovery device may include a dispenser 14 as shown in a block diagram in step 44) of FIG. 4. The dispenser 14 recovers the residual liquid adhering to the second container 12, i.e., the additional recovery liquid 12. The extract liquid 8 (first recovery liquid) and the additional recovery liquid 12 can also be combined by the dispenser 14. By using the dispenser 14, the extract liquid can be recovered efficiently.

[0052] After nucleic acid extraction, a QC step is generally performed to measure the concentration, size, etc. of the nucleic acid. The amount of liquid used in the QC step is often a very small amount, about 1 to 20 μL. The additional recovery liquid 12 may be used in the QC step.

[0053] Although the cover 3 may be omitted, using a detachable cover 3 on the magnetic bar 2 makes it easier to remove the magnetic beads 1 from the magnetic bar 2 .

[0054] Figure 5 shows the results of an experiment verifying the effect of additional recovery. In a total of 36 experiments, magnetic beads were used in an amount five times the normal amount, and elution was performed with an extract volume of 30 μL. The amount of extract 8 (first recovery liquid) and the amount of additional recovery liquid 12 from the second container 11 were measured. Next, each recovery liquid volume was divided by 30 μL, multiplied by 100, and the results were converted into the recovery rate of the extract, which was then graphed.

[0055] As a result, it was confirmed in many experiments that additional extract liquid could be recovered by contact with the second container 11. It was also found that when the recovery rate of the extract liquid 8 (first recovery liquid) was low, the recovery rate of the additional recovery liquid 12 tended to increase.

[0056] Furthermore, the liquid recovery device may include a heating / cooling mechanism 15, as shown in a block diagram in step 44) of Fig. 4. The heating / cooling mechanism 15 is a mechanism for heating and / or cooling the area for recovering the residual liquid 9 (here, the second container 11) and the magnetic bar 2.

[0057] The heating / cooling mechanism 15 may heat the magnetic bar 2, cool the second container 11, or perform both. In this way, the heating / cooling mechanism 15 makes the temperature of the magnetic bar 2 relatively higher than that of the second container 11. The heating / cooling method may be any method such as Peltier, air cooling, or water cooling.

[0058] In general, the viscosity of a liquid is temperature-dependent, and tends to decrease as the temperature increases. When the magnetic bar 2 or cover 3 with the residual liquid 9 attached thereto is brought into contact with the area for collecting the residual liquid 9, the magnetic bar 2 or cover 3 can be made relatively hotter than the area for collecting the residual liquid 9, thereby facilitating the movement of the liquid from the higher temperature area to the lower temperature area. Therefore, by heating the magnetic bar 2 or cover 3 or cooling the area for collecting the residual liquid 9, the collection of the additional collected liquid 12 can be promoted.

[0059] Another aspect that promotes liquid transfer is the material: the magnetic bar 2 or the cover 3 may be made of a hydrophobic material or may be coated hydrophobically, while the area for collecting the residual liquid 9 may be made of a hydrophilic material or may be coated hydrophilically, thereby promoting liquid transfer upon contact.

[0060] In this way, the liquid recovery device according to the first embodiment reduces loss during separation of the magnetic beads 1 and the extract (residual liquid 9).

[0061] Furthermore, by using the second container 11 separate from the first container 10, the shape of the first container 10 can be simplified.

[0062] 6 illustrates an operational flow for bringing the magnetic rod 2 with the residual liquid 9 attached into contact with an area for recovering the residual liquid 9 (here, the second container 11), which is different from that of the first embodiment. Hereinafter, explanations of parts common to the first embodiment may be omitted.

[0063] Step 61) After the extract 8 (first recovery liquid) has been recovered in the first container 10 (not shown in Figure 6), the extract is attached to the magnetic rod 2 as residual liquid 9 together with the magnetic beads 1 via the cover 3.

[0064] Step 62) The magnetic bar 2 is removed from the cover 3 and the cover 3 is brought into contact with the second container 11.

[0065] Step 63) Next, insert the magnetic bar 2 into the cover 3.

[0066] Step 64) Finally, the magnetic bar 2 and cover 3 are removed from the second container 11. In this way, a portion of the extract (residual liquid 9) adhering to the magnetic bar or cover is transferred to the second container 11 and can be recovered as additional recovery liquid 12.

[0067] The magnetic bar 2 may be a permanent magnet, for example, but the same function can also be achieved by using an electromagnet as the magnetic bar 2.

[0068] The electromagnet can switch its magnetic force on and off and change the strength of its magnetic force. The operation flow in the case of an electromagnet is as follows: when collecting magnetic beads 1 from the first container 10, the electromagnet is turned on, and when the magnetic bar 2 comes into contact with the area for collecting residual liquid 9 (for example, the second container 11), the electromagnet is turned off, and then the electromagnet is turned on again to deposit additional collected liquid 12 in the area for collecting residual liquid 9.

[0069] <Third Embodiment> Fig. 7 shows a liquid recovery device according to a third embodiment of the present invention. Hereinafter, a description of parts common to the first or second embodiment may be omitted.

[0070] 7 shows an example of an apparatus having a contact area 13, which is an area for collecting residual liquid 9, in a portion of a first container 10 containing magnetic beads 1 and an extract 6. The contact area 13 is an example of a collection area for collecting residual liquid 9 from a magnetic rod 2 that has adsorbed magnetic beads 1. The contact area 13 may or may not be flat. The contact area 13 may have any shape as long as it is an area for collecting residual liquid.

[0071] Step 71) After nucleic acids are eluted from the magnetic beads 1 into the extract 6 in the first container 10, the magnetic beads 1 in the extract 6 are attracted by the magnetic rod 2. That is, the cover 3 with the magnetic rod 2 inserted therein is inserted into the extract 6 in the first container 10, and the magnetic beads 1 are attracted by magnetic force.

[0072] Step 72) When the magnetic bar 2 is removed from the first container 10, the magnetic beads 1 and the extract 8 are separated, and the recoverable extract 8 (first recovery liquid) remains in the first container 10. At this time, the extract together with the magnetic beads 1 adheres to the magnetic bar 2 as residual liquid 9.

[0073] Step 73) Next, the magnetic bar 2 with the residual liquid 9 attached thereto is brought into contact with the contact portion 13 in the first container 10.

[0074] Step 74) Finally, when the magnetic rod 2 is removed from the contact portion 13, the extract (residual liquid 9) adhering to the magnetic rod 2 or the cover 3 moves to the contact portion 13 and can be recovered as additional recovery liquid 12.

[0075] Although not shown, such contact portions 13 may be provided at multiple locations within the container, and the operations of steps 73) and 74) may be repeated. After separating the extract 8 (first recovery liquid), the magnetic bar 2 and cover 3 may be moved along the inner wall of the first container 10 while in contact with the inner wall, until they reach the contact portions 13.

[0076] In this way, by providing the contact portion 13 inside the first container 10, the second container becomes unnecessary, and the overall configuration becomes simpler.

[0077] 7, the contact portion 13 includes a surface that is not parallel to the vertical direction, and in particular, the entire contact portion 13 is configured with a surface that is not parallel to the vertical direction. This configuration allows a larger area of ​​the contact portion 13 to come into contact with the extracted liquid that has collected at the bottom of the magnetic bar 2 due to gravity, and the amount of additional recovered liquid 12 increases.

[0078] Fourth Embodiment Furthermore, it is possible to increase the efficiency of extract recovery by increasing the magnetic force of the magnetic bar 2. The strength of the magnetic force can be changed depending on the type, size, shape, and distance from the object of the magnet.

[0079] When the magnetic rod 2 is brought into contact with the area where the residual liquid 9 is collected (e.g., the second container 11), using a magnetic rod 2 with a stronger magnetic force has the effect of strongly attracting the magnetic beads 1 to the magnetic rod 2, thereby moving a larger amount of liquid to the area where the residual liquid 9 is collected, and increasing the amount of additional collected liquid 12.

[0080] Furthermore, when collecting the magnetic beads 1 from the first container 10 after eluting the nucleic acids from the magnetic beads 1 into the extract 6, a magnetic rod 2 with a stronger magnetic force may be used in order to reduce the amount of residual liquid 9 adhering to the magnetic rod 2.

[0081] However, simply strengthening the magnetic force in all steps is not sufficient; it is preferable to use a magnetic rod 2 with a magnetic force appropriate for each step of nucleic acid extraction. For example, if the magnetic force of the magnetic rod 2 is too strong, the magnetic beads 1 attracted to the magnetic rod 2 will adhere tightly to each other, making it difficult for the magnetic beads 1 to diffuse into the binding solution 4, washing solution 5, or extraction solution 6 even when the magnetic rod 2 is removed during the washing or elution process of the nucleic acid extraction step. On the other hand, if the magnetic force is too weak when attracting the magnetic beads 1 from the binding solution 4, washing solution 5, or extraction solution 6, it will be difficult to recover a sufficient amount of magnetic beads 1 from the binding solution 4, washing solution 5, or extraction solution 6. It is preferable to adjust the magnetic force applied depending on the step by replacing the magnetic rod 2 with one with an appropriate magnetic force for each step or by adjusting the distance between the magnetic rod 2 and the magnetic beads 1 on which the magnetic force acts.

[0082] 8 shows a specific example of magnetic bar replacement. In addition to magnetic bar 2, the liquid recovery device is equipped with other magnetic bars 2a and 2b. Magnetic bars 2a and 2b have different magnetic forces from magnetic bar 2; for example, magnetic bar 2a has a stronger magnetic force than magnetic bar 2, and magnetic bar 2b has a weaker magnetic force than magnetic bar 2. By replacing these magnetic bars, i.e., by selectively using one of these magnetic bars depending on the process, the liquid recovery device can change the magnetic force acting on magnetic beads 1.

[0083] Figure 9 shows a specific example of adjusting the distance between the magnetic bar 2 and the magnetic beads 1. In addition to the magnetic bar 2, the liquid recovery device includes other magnetic bars 2c and 2d. The magnetic bar 2c is thinner than the magnetic bar 2 (i.e., it has a smaller radial dimension, and if the magnetic bar is cylindrical, it has a smaller diameter). Therefore, when the same cover 3 is used, the distance between the magnetic bar 2c and the magnetic beads 1 is greater than the distance between the magnetic bar 2 and the magnetic beads 1, and the magnetic force acting on the magnetic beads 1 can be changed depending on this distance. Similarly, a magnetic bar with a larger radial dimension than the magnetic bar 2 may be used as long as it can be accommodated in the cover 3.

[0084] The magnetic rod 2d is shorter than the magnetic rod 2. Therefore, when inserted into the cover 3, the distance between the tip of the magnetic rod 2d and the magnetic bead 1 is greater than the distance between the tip of the magnetic rod 2 and the magnetic bead 1. Similarly, a magnetic rod longer than the magnetic rod 2 may be used as long as it can be accommodated in the cover 3.

[0085] In the example of Figure 9, the distance between the tip of the magnetic rod and the magnetic bead 1 is changed by changing the length of the magnetic rod. However, even if the length of the magnetic rod does not change (for example, when the same magnetic rod 2 is used), it is possible to change the distance between the tip of the magnetic rod 2 and the magnetic bead 1 by changing the insertion length of the magnetic rod 2 into the cover 3.

[0086] In this way, the liquid recovery device can change the magnetic force acting on the magnetic beads 1 by adjusting the distance between the magnetic rod and the magnetic beads 1 .

[0087] A similar effect can also be achieved by using an electromagnet. The electromagnet can be switched on and off and the strength of the magnetic force can be changed. In particular, the magnetic force can be strengthened by adjusting the magnetic force of the electromagnet when collecting the magnetic beads 1 from the first container 10 or when contacting the magnetic rod 2 with the area where the residual liquid 9 is collected (e.g., the second container 11).

[0088] In this way, when the magnetic bar 2 is equipped with an electromagnet, the liquid recovery device can change the magnetic force acting on the magnetic beads 1 by changing the voltage applied to the magnetic bar 2.

[0089] In the above embodiment, an example has been described in which the residual liquid 9, which is the extract that adheres to the magnetic bar 2 or the cover 3 together with the magnetic beads 1, is additionally collected. Each embodiment can also be used in combination.

[0090] DESCRIPTION OF SYMBOLS 1...Magnetic beads 2, 2a to 2d...Magnetic rod 3...Cover 4...Binding liquid 5...Washing liquid 6...Extraction liquid 7...Container 8...Extraction liquid 9...Residual liquid 10...First container 11...Second container (recovery area) 12...Additional recovery liquid 13...Contact part (recovery area) 14...Dispenser 15...Heating / cooling mechanism

Claims

1. A liquid recovery device comprising: a magnetic rod for adsorbing magnetic beads; an extraction solution for extracting nucleic acid; a first container for containing the magnetic beads capable of adsorbing and releasing the nucleic acid; and a recovery region for recovering the extraction solution as a residual solution from the magnetic rod with the magnetic beads adsorbed thereon, wherein the liquid recovery device extracts the nucleic acid in the first container, and then brings the magnetic rod with the magnetic beads adsorbed thereon into contact with the recovery region to recover the residual solution.

2. The liquid recovery device according to claim 1, further comprising a cover for covering the magnetic rod, wherein the cover is detachable from the magnetic rod, and in a state where the cover is attached to the magnetic rod, the magnetic rod adsorbs the magnetic beads through the cover.

3. The liquid recovery device according to claim 1, wherein the recovery region is a second container separate from the first container.

4. The liquid recovery device according to claim 1, further comprising a dispenser, wherein the dispenser recovers the residual solution adhering to the recovery region.

5. The liquid recovery device according to claim 1, further comprising a heating and cooling mechanism, wherein the heating and cooling mechanism heats the magnetic rod and / or cools the recovery region, thereby making the temperature of the magnetic rod relatively higher than that of the recovery region.

6. The liquid recovery device according to claim 1, wherein the recovery region is provided as a contact portion in a part of the first container.

7. The liquid recovery device according to claim 1, comprising a plurality of the magnetic rods, and the liquid recovery device changes the magnetic force acting on the magnetic beads by exchanging the magnetic rods.

8. The liquid recovery device according to claim 1, wherein the liquid recovery device changes the magnetic force acting on the magnetic beads by adjusting the distance between the magnetic rod and the magnetic beads.

9. The magnetic rod includes an electromagnet, and the liquid recovery device is the liquid recovery device according to claim 1, characterized in that the magnetic force acting on the magnetic beads is changed by changing the voltage applied to the magnetic rod.

10. The liquid recovery device according to claim 6, wherein the contact portion includes a surface that is not parallel to the vertical direction.

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