Patent Publication Number: US-2021172972-A1

Title: Nucleic acid extracting device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of U.S. provisional application Ser. No. 62/945,897, filed on Dec. 10, 2019, and Taiwan application serial no. 109138168, filed on Nov. 3, 2020. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. 
    
    
     BACKGROUND 
     Technical Field 
     The disclosure relates to an extracting device, particularly to a nucleic acid extracting device. 
     Description of Related Art 
     Nucleic acid analysis is a method indispensable nowadays for the research or detection of genetics, molecular biology, or animal and plant diseases. Therefore, technologies related to the separation and extraction of nucleic acid have developed rapidly in recent years. There is a method for nucleic acid extraction that mixes the specimen, magnetic beads, and various reagents for nucleic acid extraction in a mixing chamber according to an established process and sequence, so that the nucleic acid of the specimen is bound to the magnetic beads before being separated from the magnetic beads. Timeliness is decisive factor in nucleic acid analysis. For example, for emerging infectious diseases, the faster the nucleic acid analysis of bacteria or viruses is completed, the faster the corresponding vaccine can be developed. However, general mixing devices cannot mix magnetic beads with reagents with enough efficiency, thus considerably prolonging the time for extracting and analyzing nucleic acid. 
     SUMMARY 
     The nucleic acid extracting device of the present disclosure includes a reagent containing unit, a mixing unit, and a flow channel unit. The reagent containing unit is adapted to contain at least one specimen, at least one magnetic bead, and at least one reagent for extracting. The mixing unit includes a mixing chamber and a stirring assembly. The mixing chamber includes a chamber portion and a tube portion. The stirring assembly includes a main body and an extension. The main body is provided in the chamber. The tube portion connects to the chamber. And the extension connects to the main body and extends into the tube portion. The extension and an inner wall of the tube portion have a first gap therebetween in a first direction of the tube portion. The extension and the inner wall of the tube portion have a second gap therebetween in a second direction of the tube portion. And the first gap is smaller than the second gap. The flow channel unit is connected between the reagent containing unit and the mixing unit. The specimen, the magnetic beads, and the reagent for extracting are adapted to flow from the reagent containing unit through the flow channel unit to the mixing chamber to be stirred and mixed by the stirring assembly. 
     Based on the above, in addition to the existing chamber, the mixing chamber of the present disclosure further has a tube portion extending from the chamber portion, and the stirring assembly correspondingly has an extension that extends into the tube portion. In addition, there are the first gap and the second gap of different sizes between the extension of the stirring assembly and the inner wall of the tube portion. In other words, the sizes of the gaps between the extension and the inner wall of the tube portion are not made uniformly. The non-uniform gaps between the extension of the stirring assembly and the tube portion cause the liquid to produce uneven capillary force. When the pump sucks air from an upper end of the mixing chamber, the liquid flows up and down in the tube portion repeatedly, re-dissolving the magnetic beads that are attached to the tube wall. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1  is a stereogram of a nucleic acid extracting device according to an embodiment of the disclosure. 
         FIG. 2  is an exploded-view drawing of the nucleic acid extracting device of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the nucleic acid extracting device of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the mixing unit of  FIG. 1  along line I-I. 
         FIG. 5  is an exploded-view drawing of the reagent containing unit of  FIG. 1 . 
         FIG. 6  is a locally enlarged view of the nucleic acid extracting device of  FIG. 3 . 
         FIG. 7  is a locally enlarged view of the containing structure of  FIG. 1 . 
         FIG. 8  shows a corresponding detection signal of the nucleic acid extracted by the nucleic acid extracting device of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The present disclosure provides a nucleic acid extracting device, adapted to mix magnetic beads and reagents efficiently. 
       FIG. 1  is a stereogram of a nucleic acid extracting device according to an embodiment of the disclosure.  FIG. 2  is an exploded-view drawing of the nucleic acid extracting device of  FIG. 1 .  FIG. 3  is a cross-sectional view of the nucleic acid extracting device of  FIG. 1 . In  FIG. 1  to  FIG. 3 , a nucleic acid extracting device  100  of the present embodiment includes a reagent containing unit  110 , a mixing unit  120 , and a flow channel unit  130 . The flow channel unit  130  includes, for example, an upper plate body  132  and a lower plate body  134  stacked together, and is connected between the reagent containing unit  110  and the mixing unit  120 . The reagent containing unit  110  has a plurality of reagent chambers  110   a  to  110   g , and the reagent chambers  110   a  to  110   g  are adapted to respectively contain a specimen, a plurality of magnetic beads, and various kinds of reagent for extracting. The mixing unit  120  includes a mixing chamber  122  and a stirring assembly  124 . The specimen, the magnetic beads, and the reagent for extracting are adapted to flow from the reagent containing unit  110  through the flow channel unit  130  into the mixing chamber  122  according to an established process and sequence, and are stirred and mixed by the stirring assembly  124 , so that nucleic acid of the specimen is bound to the magnetic beads before being separated from the magnetic beads. 
     In the present embodiment, the mixing chamber  122  includes a chamber portion  1221  and a tube portion  1222 . The tube portion  1222  is connected between the flow channel unit  130  and the chamber portion  1221 . An inner width of the tube portion  1222  is smaller than an inner width of the chamber portion  1221 . Note that the cross sections of the tube portion  1222  and the chamber portion  1221  are circular in the present embodiment, so the aforementioned inner widths refer to inner diameters. The stirring assembly  124  includes a main body  1241  and an extension  1242 . A width of the extension  1242  is smaller than a width of the main body  1241 . The main body  1241  is provided in the chamber portion  1221 , and the extension  1242  connects to the main body  1241  and extends into the tube portion  1222 . When the stirring assembly  124  is driven to operate, the main body  1241  stirs the specimen, the magnetic beads, and/or the reagent for extracting in the chamber portion  1221 , and the extension  1242  stirs the specimen, the magnetic beads, and/or the reagent for extracting in the tube portion  1222 . 
       FIG. 4  is a cross-sectional view of the mixing unit of  FIG. 1  along line I-I. Furthermore, in  FIG. 4 , the extension  1242  and an inner wall of the tube portion  1222  of the present embodiment have a first gap G 1  therebetween in a first direction RD 1  of the tube portion  1222  (that is, a radial direction perpendicular to an axial direction AD of the tube portion  1222 ). The extension  1242  and the inner wall of the tube portion  1222  have a second gap G 2  therebetween in a second direction RD 2  of the tube portion  1222  (that is, another radial direction perpendicular to the axial direction AD of the tube portion  1222 ). And, the first gap G 1  is smaller than the second gap G 2 . In other words, sizes of the gaps between the extension  1242  and the inner wall of the tube portion  1222  are not uniform. As a result, the capillary force between the extension  1242  and the inner wall of the tube portion  1222  is uneven. Therefore, when the reagent flows in the mixing chamber  122  due to the drive of a pump  160  and/or the stir of the stirring assembly  124 , the reagent at different places in the tube portion  1222  is stirred with different flow rates. Thus, bubbles are formed easily in the tube portion  1222 , and the magnetic beads and the reagent are mixed speedily by the stir of the stirring assembly  124  and the disturbance of the bubbles. 
     Specifically, the tube portion  1222  of the present embodiment has a cylindrical pipe  1222   a , and the extension  1242  is provided in the cylindrical pipe  1222   a . The extension  1242  has a rectangular cross section, so that the extension  1242  has a first length L in the first direction RD 1  and a second length W in the second direction RD 2 . And the first length L is greater than the second length W. This way, the sizes of the gaps between the extension  1242  and the inner wall of the tube portion  1222  may be made to be not uniform as described above. In other embodiments, the tube portion  1222  may have a pipe in other cross-sectional shapes, and the extension  1242  may have a cross section in other shapes, so that the gaps between the extension  1242  and the inner wall of the tube portion  1222  are not uniform. For example, the tube portion  1222  has a rectangular pipe, whereas the extension  1242  provided in the rectangular pipe has a circular cross section, a configuration that also includes non-uniform gaps. The present disclosure does not limit the practical shapes thereof. 
     In  FIG. 3 , the mixing unit  120  of the present embodiment includes an actuator  126  and a cover  128 . The cover  128  covers the chamber portion  1221  of the mixing chamber  122 . The stirring assembly  124  further includes a connection  1243 . The connection  1243  may pass through the cover  128  and portionially protrude to the outside of the mixing chamber  122  and connects to the actuator  126 . The actuator  126  is, for example, a motor, and is adapted to drive the stirring assembly  124  to rotate to perform the stir. In other embodiments, the actuator  126  may be other types of driving devices, and the present disclosure is not limited thereto. In addition, the mixing unit  120  may also not include the actuator  126 , but there be an actuator included in other external devices to drive the stirring assembly  124  to operate. 
     As shown in  FIG. 3 , the nucleic acid extracting device  100  of the present embodiment further includes a heating device  140 , a magnetic attracting device  150 , and a pump  160 . The heating device  140  is disposed beside the mixing chamber  122 , and is adapted to heat the mixing chamber  122  to accelerate a reaction rate of the specimen and the reagent. The magnetic attracting device  150  is disposed movably outside the tube portion  1222 , and is adapted to restrict the location of the magnetic beads by magnetic attraction, so as to prevent the magnetic beads from moving away from the tube portion  1222  unexpectedly due to the flow of the reagent. The pump  160  is connected to the mixing chamber  122  and is adapted to drive the specimen, the magnetic beads, and/or the reagent for extracting to move between the reagent containing unit  110  and the mixing chamber  122 . The heating device  140  and the magnetic attracting device  150  may be disposed respectively at positions adjacent to the chamber portion  1221  and the tube portion  1222  as shown in  FIG. 3 , but the disclosure is not limited thereto. The nucleic acid extracting device  100  may also not include the heating device  140  and/or the magnetic attracting device  150 , but there be a heating device and/or a magnetic attracting device included in other external devices to perform the heating and the magnetic attraction. When the heating and/or the magnetic attraction performed by the heating device  140  and/or the magnetic attracting device  150  is/are not required, the heating device  140  and/or the magnetic attracting device  150  may be driven to move away from the mixing chamber  122 , or turn off the heating device  140  and/or the magnetic attracting device  150 . In addition, the nucleic acid extracting device  100  may also not include the pump  160 , but there be a pump included in other external devices to drive the specimen, the magnetic beads, and/or the reagent for extracting to flow. 
     In the present embodiment, the reagent for extracting may include a lysis buffer, a binding buffer, a washing buffer, and an elution buffer. As shown in  FIG. 1 , the reagent chamber  110   a  may be adapted to contain the specimen; the reagent chamber  110   b  may be adapted to contain the lysis solution; the reagent chamber  110   c  may be adapted to contain the binding buffer; the reagent chamber  110   d  may be adapted to contain the magnetic beads; the reagent chambers  110   e  and  110   f  may be adapted to contain the washing buffer; and, the reagent chamber  110   g  may be adapted to contain the elution buffer. 
     The specific operation flow of the nucleic acid extracting device  100  of the present embodiment is described below. First, the specimen in the reagent chamber  110   a  and the lysis buffer in the reagent chamber  110   b  flow from the reagent containing unit  110  through the flow channel unit  130  to the mixing chamber  122  by the drive of the pump  160 . The heating device  140  heats the mixing chamber  122 , and the stirring assembly  124  stirs the specimen and the lysis buffer in the mixing chamber  122 , so that cell membranes of the specimen are destroyed by the lysis buffer to precipitate nucleic acid. Then, the binding buffer in the reagent chamber  110   c  and the magnetic beads in the reagent chamber  110   d  flow sequentially from the reagent containing unit  110  through the flow channel unit  130  to the mixing chamber  122  by the drive of the pump  160 . The heating device  140  heats the mixing chamber  122 , and the stirring assembly  124  stirs the specimen, the magnetic beads, and the binding buffer in the mixing chamber  122 , so that the nucleic acid of the specimen is bound to the magnetic beads by the binding buffer. Then, the magnetic beads are prevented from moving by the magnetic attraction of the magnetic attracting device  150 , and waste liquid generated by the reaction between the specimen and the reagent in the mixing chamber  122  is driven by the pump  160  to pass through the flow channel unit  130  to be discharged to the reagent containing unit  110 ; and the reagent containing unit  110  may include a waste liquid chamber or use an existing reagent chamber to contain the waste liquid. 
     Next, the washing buffer in the reagent chamber  110 e flows from the reagent containing unit  110  through the flow channel unit  130  to the mixing chamber  122  by the drive of the pump  160 . The stirring assembly  124  stirs the magnetic beads and the washing buffer in the mixing chamber  122  to wash the magnetic beads for the first time with the washing buffer. The magnetic attraction force of the magnetic attracting device  150  prevents the magnetic beads from moving, and the pump  160  drives the waste liquid generated in the mixing chamber  122  after the first wash to pass through the flow channel unit  130  to be discharged to the reagent containing unit  110 ; and the reagent containing unit  110  may include a waste liquid chamber or use an existing reagent chamber to contain the waste liquid. Then, the washing buffer in the reagent chamber  110   f  flows from the reagent containing unit  110  through the flow channel unit  130  to the mixing chamber  122  by the drive of the pump  160 . The stirring assembly  124  stirs the magnetic beads and the washing buffer in the mixing chamber  122  to wash the magnetic beads for the second time with the washing buffer. The magnetic attraction force of the magnetic attracting device  150  prevents the magnetic beads from moving, and the pump  160  drives the waste liquid generated in the mixing chamber  122  after the second wash to pass through the flow channel unit  130  to be discharged to the reagent containing unit  110 ; and the reagent containing unit  110  may include a waste liquid chamber or use an existing reagent chamber to contain the waste liquid. The elution buffer in the reagent chamber  110   g  flows from the reagent containing unit  110  through the flow channel unit  130  to the mixing chamber  122  by the drive of the pump  160 . The stirring assembly  124  stirs the magnetic beads and the elution buffer in the mixing chamber  122  to separate the nucleic acid from the magnetic beads with the elution buffer, and thereby extracting the nucleic acid. 
     In different steps of the foregoing operation flow, the amount of reagents in the mixing chamber  122  may be different. To make the mixing chamber  122  suitable for various amounts of reagents, a connecting end of the chamber portion  1221  to the tube portion  1222  may be designed to be funnel-shaped as shown in  FIG. 1  to  FIG. 3 , such that inner widths of parts of the chamber portion  1221  gradually taper from top to bottom. This way, when the amount of the reagent in the mixing chamber  122  is large, the part with a larger inner width is capable of providing enough space to contain the reagent, and when the amount of the reagent in the mixing chamber  122  is small, the part with a smaller inner width is capable of preventing the reagent from being excessively dispersed in a horizontal direction due to the excessive width of the mixing chamber  122 , so as to reduce the residual in corners of the chamber portion  1221 . Correspondingly, the shape of the funnel-shaped part of the main body  1241  of the stirring assembly  124  provided in the chamber portion  1221  may also be changed accordingly. Specifically, the main body  1241  of the stirring assembly  124 , which is disposed at the corresponding tapered part of the chamber portion  1221 , may be designed as an airfoil and taper toward the extension  1242 , so that even a small amount of reagent may be well stirred. 
       FIG. 5  is an exploded-view drawing of the reagent containing unit of  FIG. 1 . In  FIG. 3  and  FIG. 5 , the reagent containing unit  110  of the present embodiment includes a containing structure  112 . The reagent chambers  110   a  to  110   g  are formed in the containing structure  112 . A bottom of the containing structure  112  has a plurality of channels  112   a , and the channels  112   a  are respectively connected to the reagent chambers  110   a  to  110   g . And each of the reagent chambers  110   a  to  110   g  communicates with the flow channel unit  130  through the corresponding channel  112   a.    
     Furthermore, the reagent containing unit  110  further includes a plurality of elastic seals  114  and a bottom plate  116 . The elastic seals  114  are disposed at the bottom of the containing structure  112  and are corresponding respectively to the channels  112   a . The bottom plate  116  is assembled to the bottom of the containing structure  112 , for example, in a screw-locked manner, and each of the elastic seals  114  is restricted between the containing structure  112  and the flow channel unit  130 .  FIG. 6  is a locally enlarged view of the nucleic acid extracting device  100  of  FIG. 3 . In  FIG. 6 , each of the elastic seals  114  has a through hole  114   c  as well as a top surface  114   a  and a bottom surface  114   b  opposite to each other. The through hole  114   c  extends from the top surface  114   a  to the bottom surface  114   b . Each of the elastic seals  114  is disposed in the bottom plate  116 , and the top surface  114   a  and the bottom surface  114   b  of each elastic seal  114  respectively contact the containing structure  112  and the flow channel unit  130 . The through hole  114   c  communicates with the corresponding channel  112   a , so that each of the reagent chambers  110   a  to  110   g  may communicate with the flow channel unit  130  through the corresponding channel  112   a  and the corresponding through hole  114   c . The material of each elastic seal  114  may be rubber or other elastic material suitable to perform sealing between the containing structure  112  and the flow channel unit  130 , such that unexpected leakage of the reagent there may be prevented. In addition, each of the channels  112   a  of the containing structure  112  is, for example, a capillary, and the capillary resistance thereof further prevents the reagent from leaking. 
     Specifically, each of the elastic seals  114  is disposed in the opening  116   a  of the bottom plate  116 . And each of the elastic seals  114  is in a stepped shape as shown in  FIG. 6 , and may be restricted by a flange  116   b  in the opening  116   a  to be at the bottom of the containment structure  112 . The through hole  114   c  of each elastic seal  114  is adapted to communicate with an end  130   a   1  (marked in  FIG. 6 ) of the flow channel  130   a  (marked in  FIG. 2  and  FIG. 3 ) provided between the upper plate body  132  and the lower plate body  134  of the flow channel unit  130 . 
     In the present embodiment, the flow channel unit  130  has, for example, only one flow channel  130 a, and one end of the flow channel  130 a is connected to the mixing chamber  122 . The reagent containing unit  110  is rotatably disposed on the flow channel unit  130  along a rotation axis RA (shown in  FIG. 1 ) and is adapted to rotate, so that any one of the reagent chambers  110   a  to  110   g  may be correspond to the other end of the flow channel  130   a  (i.e., the end  130   a   1  shown in  FIG. 6 ), such that one of the reagent chambers  110   a  to  110   g  communicates with the mixing chamber  122 . In the present embodiment, the reagent containing unit  110  rotates via the drive of, for example, a motor or other suitable drivers. In other embodiments, the communication between the reagent chambers  110   a  to  110   g  and the mixing chamber  122  may also be switched by adopting other suitable methods and/or structures, and the present disclosure is not limited thereto. 
       FIG. 7  is a locally enlarged view of the containing structure of  FIG. 1 . In  FIG. 7 , in the present embodiment, the reagent chamber  110   d  corresponding to the magnetic beads has an inlet  110   d   1 , an outlet  110   d   2 , and a guide surface  110   d   3 , and a bottom of the reagent chamber  110   d  has a recess  110   d   4 . The outlet  110   d   2  is provided in the recess  110   d   4 , and the recess  110   d   4  is adapted to contain the magnetic beads. The location of the inlet  110   d   1  is higher than the location of the outlet  110   d   2 , and the guide surface  110   d   3  extends obliquely from the inlet  110   d   1  to the outlet  110   d   2 . When the magnetic beads are to be moved to the mixing chamber  122  shown in  FIG. 1 , a suitable reagent may be driven to enter the reagent chamber  110   d  from the inlet  110   d   1 , so that the reagent drives the magnetic beads to move out of the reagent chamber  110   d  from the outlet  110   d   2  and move to the mixing chamber  122  through the flow channel unit  130 . Since the magnetic beads are collected to the lower recess  110   d   4  in advance, and the reagent flows downward from the inlet  110   d   1  which is above the location of the outlet  110   d   2 , and drives the magnetic beads to move away from the reagent chamber  110   d  through the outlet  110   d   2 , the magnetic beads are prevented from dashing out of the reagent chamber  110   d  due to the impact of the reagent. 
       FIG. 8  shows a corresponding detection signal of the nucleic acid extracted by the nucleic acid extracting device of  FIG. 1 . As shown in  FIG. 8 , a significant detection signal appears between the nucleic acid length of 150 bp to 200 bp, indicating that the nucleic acid extracting device  100  of the present embodiment indeed extracts nucleic acid from the specimen. 
     In sum, in addition to the existing chamber, the mixing chamber of the present disclosure further includes a tube portion extending from the chamber portion, and the stirring assembly correspondingly includes an extension that extends into the tube portion. In addition, there are the first gap and the second gap of different sizes between the extension of the stirring assembly and the inner wall of the tube portion. In other words, the sizes of the gaps between the extension and the inner wall of the tube portion are not made uniformly. The non-uniform gaps between the extension of the stirring assembly and the tube portion cause the liquid to produce uneven capillary force. When the pump sucks air from the upper end of the mixing chamber, the liquid flows up and down in the tube portion repeatedly, re-dissolving the magnetic beads that are attached to the tube wall. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of the present disclosure provided they fall within the scope of the following claims and their equivalents.