Abstract:
Provided is a capillary electrophoresis device including a holder preventing a septum from coming off when a capillary is pulled out, and also allowing containers to be taken out in any order. In the capillary electrophoresis device for separating and analyzing a sample such as a DNA and a protein by electrophoresis, the holder includes: a septum having a capillary hole through which a capillary penetrates; a container for storing a solution; and a container-accommodation unit for accommodating the container. A hole formed in the septum engages with an engagement portion formed on the container, and thereby the septum is held to cover the container.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a capillary electrophoresis device for separating and analyzing a sample such as a DNA and a protein by electrophoresis. Particularly, the present invention relates to a holder for holding a solution such as a sample solution, a buffer solution, an assy solution, and a rinse. 
     2. Description of the Related Art 
     A solution for a sample, an assy, a buffer, a rinse or the like used in a capillary electrophoresis device is stored in a container hermetically sealed by a septum. A capillary comes into contact with the liquid in the container through a hole opened in the septum. 
     The septum is made of an elastic material. When the capillary penetrates into the hole in the septum, the hole contracts by an elastic force, and thus the septum hermetically seals the surrounding of the capillary. When the capillary is inserted into the hole in the septum, a driving force is needed to push the capillary into the hole against a friction force between the capillary and the hole. Additionally, when the capillary is pulled out from the hole in the septum, a driving force is needed to pull out the capillary against the friction force. When the capillary is pulled out from the hole in the septum, the septum may be also lifted from the container due to the friction force between the capillary and the hole. When the friction force is large, not only the septum but also the container may be lifted together with the capillary. 
     In order to solve this problem, a stripper has been used conventionally as described in WO2002/079773 or the like. When a capillary is pulled out from a septum, the stripper prevents the septum and its container from lifting up by pressing the septum down. 
     Moreover, a capillary electrophoresis device described in WO2002/090968 is provided with a guide which prevents various containers, such as a buffer container and a microtiter plate for storing a sample, from being taken off from a container-accommodation unit, when a capillary is inserted into or pulled out from the various containers. 
     SUMMARY OF THE INVENTION 
     In a capillary electrophoresis device described in WO2002/079773, the stripper continuously applies a downward force to an autosampler, while being in contact with the autosampler. The autosampler is driven by, for example, a stepper motor. When the stepper motor is being excited, the autosampler does not move owing to a holding torque of the stepper motor. Nevertheless, when a power supply of the electrophoresis device is turned off, the stepper motor is released from the excitation state, and thus the holding torque is ceased. At this point, the autosampler may be pushed downward by the stripper in some cases. 
     In the capillary electrophoresis device described in WO2002/090968, the guide hinders the container from being attached to the container-accommodation unit in a direction in which the capillary is inserted or pulled (hereinafter, referred to as a capillary-drawing direction). For this reason, the container is attached to the container-accommodation unit from a side surface of the container-accommodation unit in a direction perpendicular to the capillary-drawing direction. As a result, the direction in which the container is attached is limited, which makes the handling of the capillary electrophoresis device inconvenient. 
     An object of the present invention is to provide a capillary electrophoresis device which allows a capillary to be easily pulled out from a septum. 
     The present invention relates to a capillary electrophoresis device for separating and analyzing a sample such as a DNA and a protein by electrophoresis, and also relates to a holder for the capillary electrophoresis device. The holder includes: a septum having a capillary hole through which a capillary penetrates; a container for storing a solution; and a container-accommodation unit for accommodating the container. An engagement portion formed on the septum engages with an engagement portion formed on the container, and thereby the septum is held to cover the container. 
     Moreover, the containers are accommodated into the container-accommodation unit in a vertical direction, and thereby each of the containers can be disposed into any position in any order. 
     According to the present invention, when the capillary is pulled out, the septum is prevented from coming off. Moreover, the containers are taken out in any order. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an overview of a capillary electrophoresis device according to an embodiment of the present invention. 
         FIG. 2  shows a configuration of a capillary array in the capillary electrophoresis device according to the embodiment. 
         FIGS. 3A and 3B  are respectively an exploded view and an assembled view of a holder for the capillary electrophoresis device according to the embodiment. 
         FIGS. 4A and 4B  show the holder in use for the capillary electrophoresis device according to the embodiment. 
         FIGS. 5A to 5D  illustrate a method for assembling a holder for a capillary electrophoresis device according to the embodiment. 
         FIGS. 6A to 6D  show examples of engagement portions of a container and a septum in the holder for the capillary electrophoresis device according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows an overview of a capillary electrophoresis device according to an embodiment of the present invention. The capillary electrophoresis device of this embodiment includes: a capillary array  102  having a single capillary  101  or the multiple capillaries  101 ; a pump mechanism  103  for injecting the capillary  101  with a polymer; an optical system  104  which irradiates a sample in the capillary  101  with light to detect fluorescence from the sample; a high-voltage power supply  105  for applying a high voltage to the capillary  101 ; an oven  106  for keeping a temperature of the capillary  101  constant; and an autosampler  107  for transferring a container storing a sample, solution, and the like therein. 
     The capillary  101  is a replaceable member, and replaced with a fresh capillary  101  when a measurement method is changed, when the capillary  101  is fractured or when the quality thereof is deteriorated. The capillary  101  is configured of a glass tube with an inner diameter of several tens to several hundreds of micrometer, and an outer diameter of several hundreds of micrometer. The surface of the capillary  101  is coated with polyimide. The capillary  101  is filled with separation media for providing a migration time difference during electrophoresis. Some types of separation media have fluidity, and others do not. In this embodiment, a polymer having fluidity is used. 
     A capillary head  205  is provided to one end of the capillary  101 , and a capillary cathode electrode  206  is formed at the other end of the capillary  101 . The capillary head  205  is formed by bundling the end of capillary  101 , and functions to connect the pump mechanism  103  with the capillary  101 . The capillary cathode electrode  206  comes into contact with the sample, solution, and the like. On the capillary cathode electrode side, the capillary  101  is fixed by a load header  203 . The load header  203  is provided with an cathode electrode  114 . 
     The optical system  104  is formed of an irradiation system and a detection system. The optical system  104  functions to irradiate, with an exciting light, a portion where the polyimide-coated film of the capillary  101  is removed, i.e. a detection portion. The detection system functions to detect fluorescence from the sample in the detection portion of the capillary  101 . The sample is analyzed with the light detected by the detection system. 
     The pump mechanism  103  includes a syringe  108 , a block  109 , a check valve  110 , a polymer container  111  and a anode buffer container  112 . By connecting the capillary head  205  to the block  109 , the capillary  101  is connected to a flow path in the block  109 . By an operation on the syringe  108 , a polymer in the polymer container  111  is filled into the capillary  101  or the capillary  101  is refilled with that polymer, via the flow path in block  109 . The refilling of the polymer in the capillary  101  is performed at each measurement to improve the measurement performance of the capillary electrophoresis device. 
     A anode electrode  113  is disposed in the anode buffer container  112 . The high-voltage power supply  105  applies a high voltage between the anode electrode  113  and the cathode electrode  114 . 
     The oven  106  holds the capillary array  102  in a planar form between temperature-controlling plates mounted with an insulator and a heater to keep the temperature of the capillary constant. The temperature-controlling plates are mounted with a temperature sensor for feedback. By fixing the load header  203  of the capillary array to the oven, the tip end of the capillary head  205  can be fixed to a desired position. 
     The autosampler  107  is provided with three electric motors and linear guides for moving a moving stage, and thereby the moving stage is movable in three-axis directions of upward-downward, rightward-leftward and forward-backward. The moving stage can transfer the buffer container, rinse container, waste container and sample plate to the capillary cathode electrode  206  as necessary. 
       FIG. 2  shows the specifics of the capillary array  102  in the capillary electrophoresis device shown in  FIG. 1 . The capillary head  205  is provided to the one end of the capillary  101 , and the capillary cathode electrode  206  is formed at the other end of the capillary  101 . The load header  203  is mounted with a metallic hollow electrode. The capillary cathode electrode  206  penetrates through the hollow electrode, and protrudes from the tip end. The capillary  101  is fixed on a sheet  207 . The sheet  207  is held by the load header  203 . The optical system  104  includes a cone lens  208  and a reference base  204 . The detection portion of the capillary  101  is held on the reference base  204 . The detection portion of the capillary  101  is irradiated with an exciting light from the light source via the cone lens  208 . 
     Next, description will be given of an example of a holder used for the capillary electrophoresis device of the present invention with reference to  FIGS. 3A and 3B . As shown in  FIG. 3A , the holder of this example includes a container  300 , a container-accommodation unit  310  and a septum  320 . 
     The container  300  includes: a reservoir  301  which stores a solution such as a sample solution, buffer solution, assy solution, and rinse; a pair of first engagement portions  302  provided on the top surface of the reservoir  301 ; and a pair of second engagement portions  303  formed on side surfaces of the reservoir  301 . The second engagement portion  303  includes a groove  303   b  and a convex portion  303   a  formed in the groove. 
     The container-accommodation unit  310  includes: a holding portion  311  for holding the container  300 ; and a pair of engagement portions  313  protruding from the top surface of the holding portion. The engagement portion  313  includes: a boss  313   b  and a hook  313   a  formed on the tip end of the boss. A notch  312  is formed in the holding portion  311 . 
     The septum  320  includes capillary holes  321  through which the capillaries penetrate; and engagement portions which engage with the first engagement portions  302 . The engagement portion includes a through hole  322 . The septum  320  is made of an elastic material such as a rubber or a resin. 
       FIG. 3B  shows the assembled holder of this embodiment. In the holder, the container  300  is accommodated in the container-accommodation unit  310 , and the septum  320  is mounted on the container  300  so as to hermitically seal the top surface of the container  300 . In  FIGS. 3A and 3B , the single container  300  is accommodated in the container-accommodation unit  310 ; however, the multiple containers  300  may be accommodated therein, while being arranged in line. For example, when the three containers  300  are accommodated, the interior size of the container-accommodation unit  310  should be designed to accommodate the three containers  300 . 
     Next, description will be given of a capillary-drawing direction as well as a direction in which the container  300  is put into container-accommodation unit  310 . In the capillary electrophoresis device of this embodiment, the capillary-drawing direction is perpendicular to a direction in which the septum  320  lies. In other words, the capillary-drawing direction is parallel to the depth direction of the container-accommodation unit  310 . Meanwhile, the direction in which the container  300  is put into the container-accommodation unit  310  is the same as the capillary-drawing direction. In this embodiment, the container  300  is put into the container-accommodation unit  310  from the top of the unit  310 . Thus, the direction in which the container  300  is put is the same as the capillary-drawing direction. 
       FIGS. 4A and 4B  show the holder in use according to the embodiment. The first engagement portions  302  of the container  300  penetrate into the holes  322  in the septum  320 . The hooks  313   a  of the container-accommodation unit  310  engage with the convex portions  303   a  of the container  300 . As illustrated, the reservoir  301  stores a solution  401  such as a buffer solution, assy solution, rinse, and washing waste. 
     The capillary hole  321  in the septum  320  includes: a cylinder-shaped concave portion  321   a ; a cone-shaped bottom portion  321   b ; and a through hole  321   c  formed at the lower end of the bottom portion  321   b . The through hole  321   c  may be formed of a thin film with a cut in a straight line. The concave portion  321   a  and the bottom portion  321   b  are formed so as to protrude from the bottom surface of the septum  320 . 
     When the capillary cathode electrode  206  is inserted into the capillary hole  321  of the septum  320 , the septum  320  receives a downward force due to a friction force between the capillary cathode electrode  206  and the through hole  321   c . Nevertheless, since the periphery of the septum  320  is supported by the top surface of the container  300 , the septum  320  would not be moved further downward. 
     When the capillary cathode electrode  206  is pulled out from the capillary hole  321  in the septum  320 , the septum  320  receives an upward force due to a friction force between the capillary cathode electrode  206  and the through hole  321   c . Nevertheless, since the holes  322  in the septum  320  and the first engagement portions  302  of the container  300  engage with each other, the septum  320  would not move upward away from the container  300 . When the capillary cathode electrode  206  is pulled out from the capillary hole  321  in the septum  320 , the container  300  also receives an upward force due to the friction force between the capillary cathode electrode  206  and the through hole  321   c . Nevertheless, since the convex portions  303   a  of the container  300  and the hooks  313   a  of the container-accommodation unit  310  engage with each other, the container  300  would not be moved upward away from the container-accommodation unit  310 . 
     In this manner, according to this embodiment, even when the capillary cathode electrode  206  is inserted into the capillary hole  321  in the septum  320 , and even when the capillary cathode electrode  206  is pulled out from the capillary hole  321  in the septum  320 , the septum  320  and the container  300  never moves. 
     The septum  320  is made of a rubber-like elastic material. Accordingly, when the capillary cathode electrode  206  is not inserted into the capillary hole  321  in the septum  320 , the capillary hole  321  is being contracted and closed due to the elastic force. Meanwhile, when the capillary cathode electrode  206  is inserted into the capillary hole  321  in the septum  320 , the hole  321  also contracts due to the elastic force to hermetically seal the clearance between the hole  321  and the capillary cathode electrode  206 . Thus, the interior of the container  300  is hermitically sealed all the time. 
     In this embodiment, the concave portion  321   a  and the bottom portion  321   b  are formed to protrude downward from the bottom surface of the septum  320 , and the through hole  321   c  is formed in the bottom portion  321   b . Accordingly, this embodiment has an advantage of facilitating the expansion and the contraction of the through hole  321   
     With reference to  FIGS. 5A to 5D , description will be given of a method for assembling the container  300  and the septum  320  together with the container-accommodation unit  310 . The first engagement portion  302  of the container  300  includes a head  302   a  and a constriction  302   b . The head  302   a  and the constriction  302   b  have circular cross sections. The outer diameter of the head  302   a  is larger than that of the constriction  302   b . As shown in  FIG. 5A , the septum  320  is disposed on the top surface of the container  300  so that the hole  322  in the septum  320  can engage with the head  302   a  of the first engagement portion  302  on the container  300 . When the septum  320  is pushed onto the container  300 , the inner diameter of the hole  322  in the septum  320  is elastically deformed and enlarged. When the septum  320  is further pushed onto the container  300 , the inner diameter of the hole  322  in the septum  320  is enlarged so that the head  302   a  can pass through the hole  322 . After the head  302   a  of the first engagement portion  302  on the container  300  passes through the hole  322 , the inner diameter of the hole  322  in the septum  320  returns to the original size. As shown in  FIG. 5B , the hole  322  in the septum  320  engages with the constriction  302   b  of the first engagement portion  302  on the container  300 . 
     When the container  300  is inserted into the container-accommodation unit  310  as shown in  FIG. 5C , the hook  313   a  of the container-accommodation unit  310  comes into contact with the convex portion  303   a  of the container  300 . When the container  300  is further inserted into the container-accommodation unit  310 , the hook  313   a  of the container-accommodation unit  310  is elastically deformed to ride over the convex portion  303   a  of the container  300 . As shown in  FIG. 5D , after the hook  313   a  of the container-accommodation unit  310  rides over the convex portion  303   a  of the container  300 , the hook  313   a , as well as the container-accommodation unit  310  returns to the original shapes. In this manner, the second engagement portions  303  of the container  300  engage with the engagement portions  313  of the container-accommodation unit  310 . In this state, even if the container  300  receives a force such that the container  300  may be lifted and separated from the container-accommodation unit  310 , the container  300  will not be separated from the container-accommodation unit  310 , since the convex portions  303   a  of the container  300  are engaged with the hooks  313   a  of the container-accommodation unit  310 . 
     According to the holder for the capillary electrophoresis device of the present invention, when the capillary is pulled out from the septum, the taking off of the septum from the container and the taking off of the container from the container-accommodation unit are certainly prevented, since the holes  322  in the septum  320  and the first engagement portions  302  on the container  300  engage with each other. 
     According to the holder for the capillary electrophoresis device of this embodiment, the hole  322  is formed in the septum  320  so as to protrude downward from the bottom surface of the septum  320 . Thereby, the hole  322  is elastically deformed only slightly. Therefore, only the minimum external force should be applied to engage the holes  322  in the septum  320  with the first engagement portions  302  on the container  300 . Moreover, when the capillary is inserted or pulled out, the friction force between the capillary and the hole in the septum is small, and the capillary is inserted or pulled out with a small force. 
     According to the holder for the capillary electrophoresis device of this embodiment, the septum is mounted on the container in the capillary-drawing direction, and the container is inserted into the container-accommodation unit in the capillary-drawing direction. Thus, in a case where the multiple containers are accommodated in the container-accommodation unit, any one of the containers can be put in or out in any order. Therefore, the controllability of the holder is improved. 
     Description will be given of examples of engagement portions of the container and the septum in a holder for the capillary electrophoresis device according to another embodiment with reference to  FIGS. 6A to 6D . The holders in these examples include the container  300 , the container-accommodation unit  310  and the septum  320 . The septum  320  is provided with the capillary holes  321  through which the capillaries penetrate. The way of inserting the container  300  into the container-accommodation unit  310  is the same as that in the example in  FIG. 5 . 
     In the example shown in  FIG. 6A , a hole  305  is formed in a flange  304  on an upper end of the container  300 . An engagement portion  325  is provided to the septum  320 . The engagement portion  325  is a boss including a head  325   a  and a constriction  325   b . This boss extends downward from the septum  320 , that is, in the direction of the gravitational force. The constriction  325   b  of the engagement portion  325  engages with the hole  305  of the container  300 , and the head  325   a  of the engagement portion  325  protrudes from the hole  305  of the container  300 . By engaging the engagement portion  325  of the septum  320  with the hole  305  of the container  300 , the septum  320  is held by the container  300 . 
     In the example shown in  FIG. 6B , a gripper  326  is formed on an edge portion of the septum  320 . By engaging the gripper  326  of the septum  320  with the flange  304  on the upper end of the container  300 , the septum  320  is held by the container  300 . In the example shown in  FIG. 6C , a gripper  307  is formed on an upper end of the container  300 . By engaging an edge portion of the septum  320  with the gripper  307  of the container  300 , the septum  320  is held by the container  300 . 
     The structure shown in  FIG. 6D  is in combination of the examples shown in  FIG. 6A  and  FIGS. 5A to 5D , and is a left-right asymmetrical structure. Specifically, the septum  320  is provided, on one end thereof, with the engagement portion  325  that is the boss including the head  325   a  and the constriction  325   b . The hole  305  is formed in the flange  304  of the container  300 . The engagement portion  325  of the septum  320  engages with the hole  305  of the container  300 . On the other end of the septum  320 , the container  300  is provided, on the upper end thereof, with the engagement portion  302  that is the boss including the head  302   a  and the constriction  302   b . The septum  320  is provided with the hole  322 . The head  302   a  of the engagement portion  302  on the container  300  engages with the hole  322  in the septum  320 . 
     In the examples of the engagement portions of the container and the septum shown in  FIGS. 6A to 6D , when the capillary is pulled out from the septum, the detachment of the septum from the container and the detachment of the container from the container-accommodation unit are certainly prevented, since the septum  320  and the container  300  engage with each other. Furthermore, since the capillary hole  321  in the septum  320  does not deform, this makes the friction between the capillary hole  321  and the capillary minimum. Therefore, the capillary is easily pulled out from the septum. 
     The same holds true for a case where the capillary is inserted into the septum in addition to the case where the capillary is pulled from the septum. Specifically, when the capillary is inserted into the septum, the capillary hole  321  in the septum  320  does not deform. Thus, this allows the friction between the capillary hole  321  and the capillary minimum. Therefore, the capillary is easily inserted into the septum. 
     The present invention is not limited to the above embodiments. Those skilled in the art would easily understand that various modifications can be made within the scope of the invention described in the section of claims.