Patent Publication Number: US-2020290051-A1

Title: Gene amplification device

Description:
TECHNICAL FIELD 
     The present invention relates to a gene amplification device that performs gene amplification by repeatedly heating and cooling a reaction container housing a gene. 
     BACKGROUND ART 
     A PCR (polymerase chain reaction) method is known as a technique for amplifying a gene. In the PCR method, a reagent is added to a specimen containing DNA, and the DNA is amplified by periodically raising and lowering a temperature of the mixture. In order to carry out such a PCR method, a gene amplification device (also referred to as a thermal cycler) that houses a reaction container containing a specimen and a reagent and executes gene amplification processing for periodically performing heating and cooling of the reaction container has been proposed and also implemented (see, for example, Patent Document 1). 
     As disclosed in Patent Document 1, the gene amplification device includes a main body provided with a reaction container holder having a plurality of container insertion parts for inserting the reaction containers therein and a cover attached to the main body so as to be openable and closable. The reaction container holder is constituted by a heat conductive block, and a Peltier element for raising and lowering a temperature of the reaction container holder is provided in the main body. The cover is provided with a heat lid which has functions of pressing a lid attached to an upper surface of a main body of the reaction container when the cover is closed and heating the lid of the reaction container to a predetermined temperature. 
     By providing the heat lid in the cover, when the cover is closed, the lid is pressed toward the main body by the heat lid, a sealing property of the reaction container is improved, and evaporation of a reaction liquid to the outside of the reaction container is prevented. Further, by heating the lid of the reaction container by the heat lid before the gene amplification processing is carried out, water vapor generated by the gene amplification processing is prevented from condensing on the lid. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Translation of PCT Publication No. 2016-519614 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     As described above, the lid is attached to the upper portion of the main body of the reaction container installed in the gene amplification device, and the lid is heated to the predetermined temperature while being pressed by the heat lid. Accordingly, evaporation of the reaction liquid and dew condensation when the gene amplification processing is carried out are prevented. However, in such a conventional configuration, it has been found that evaporation of the reaction liquid to the outside of the reaction container is not completely prevented in some cases. 
     When the reaction liquid evaporates from the reaction container, an amount of the reaction liquid varies when the gene amplification processing is started and when it ends, and a reaction state in the reaction container changes. Alternatively, pressure applied by a plate becomes nonuniform among a plurality of reaction containers installed in the reaction container holder, so that an amount of evaporation of the reaction liquid becomes nonuniform. Accordingly, the amount of the reaction liquid in each reaction container varies, and the reaction cannot be compared accurately. 
     In addition, in the gene amplification processing, the reaction container is heated to a high temperature of about 95° C. to thermally deform the reaction container, sealability between the main body and the lid of the reaction container after completion of the gene amplification processing worsens, and the lid is easily detached from the main body in many cases. If the lid of the reaction container is easily detached from the main body, there is also a problem that a gene amplification product in the reaction container leaks to the outside, causing environmental pollution and contamination. 
     Therefore, the present invention aims at improving a sealing property of a reaction container over a period before and after implementing gene amplification processing. 
     Solution to the Problems 
     A gene amplification device according to the present invention includes: a reaction container holder having a container insertion part into which a main body of a reaction container including the main body and a lid attached to an upper portion of the main body is inserted, the reaction container holder having a function of raising and lowering a temperature of the reaction container inserted into the container insertion part; and a heat seal part disposed near an contacting portion between the main body and the lid of the reaction container inserted into the container insertion part of the reaction container holder, the heat seal part heating a temperature of the contacting portion to a temperature higher than a heatproof temperature of the main body or the lid of the reaction container. 
     A material of the main body and the lid of the reaction container is a resin such as polypropylene. When the heat seal part disposed near the contacting portion between the main body and the lid reaches a temperature higher than the heatproof temperature of the material of the main body or the lid, the resin at the contacting portion is thermally deformed. Thus, the main body and the lid are adhered to each other, and the reaction container is heat-sealed. Hereinafter, an operation of heating the heat seal part to a temperature higher than the heatproof temperature of the main body or the lid of the reaction container to heat-seal the contacting portion between the main body and the lid is referred to as a “heat sealing operation”. 
     Since the heat seal part heats the contacting portion between the main body and the lid of the reaction container, as long as the heat seal part can perform its function, it may be provided on the reaction container holder side or on a heat lid side. However, from the viewpoint of preventing evaporation of a reaction liquid inside the reaction container and thermal deformation of the main body, it is not desirable to heat the entire reaction container holder to a temperature higher than the heatproof temperature of the main body or the lid of the reaction container. Accordingly, when the heat seal part is provided on the reaction container holder side, it is necessary to perform a temperature raising operation of the heat seal part independently of a temperature raising and lowering operation of the reaction container holder, and it is necessary that the heat seal part and the reaction container holder are thermally separated. Thus, it is difficult to realize the heat seal part with a simple structure. 
     Therefore, it is preferable that the heat seal part in the present invention is provided as a part of the heat lid. The heat lid is disposed above the reaction container holder holding the reaction container in the container insertion part to be in contact with the lid of the reaction container, and has a function of heating a temperature of the lid to a predetermined temperature. As described above, the heat lid is provided to contact with the lid of the reaction container installed in the reaction container holder to heat the lid. Therefore, if the part of the heat lid is disposed near the contacting portion between the main body and the lid of the reaction container, only by heating the heat lid to a temperature higher than the heatproof temperature of the main body or the lid, the heat seal part can be realized without providing a new heater or the like, and an increase in cost can be suppressed. Since the heat lid is in contact with the lid of the reaction container and is not in direct contact with the main body, evaporation of the reaction liquid or thermal deformation of the main body by heating the main body more than necessary is prevented. 
     An example of a configuration for realizing the heat seal part as a part of the heat lid is described as follows: the heat lid is provided with a recess, on a lower surface, fitted with the lid of the reaction container projecting upward from the container insertion part of the reaction container holder, and a part of the heat lid is disposed near the contacting portion between the main body and the lid of the reaction container, when the lid of the reaction container is fitted into the recess. By adopting such a configuration, it is possible to realize the heat seal part at low cost. 
     In addition, in the conventional gene amplification device, it is general that a lower surface of the heat lid is a flat surface, and the lids of the plurality of reaction containers are pressed against the flat surface. Accordingly, there is a problem that force pressing the lids tends to become nonuniform. 
     On the other hand, when the recess for fitting with the lid of the reaction container is provided on the lower surface of the heat lid, the heat lid can stably and uniformly press the lid of the reaction container toward the main body, and it is possible to further improve a sealing property of the reaction container. 
     In addition, the gene amplification device of the present invention may be configured to automatically perform the above heat sealing operation. Specifically, a controller for controlling a temperature rising operation of the heat lid may be provided, and the controller may have a function of executing a heat sealing operation for raising a temperature of the heat lid to a temperature higher than the heatproof temperature of the main body or the lid of the reaction container, in a state in which the part of the heat lid is disposed near the contacting portion between the main body and the lid of the reaction container. 
     In the above case, it is preferable that the controller is configured to execute the heat sealing operation before starting gene amplification processing. Then, sealing of the reaction container is maintained over a period before and after the gene amplification processing, and evaporation and leakage of the reaction liquid are prevented. 
     The controller may also control a temperature raising and lowering operation of the reaction container holder together with the temperature raising operation of the heat lid. In that case, it is preferable that a temperature of the reaction container holder is not raised during execution of the heat sealing operation. As a result, evaporation of the reaction liquid during the heat sealing operation is suppressed. 
     Effects of the Invention 
     A gene amplification device according to the present invention includes a heat seal part disposed near an contacting portion between a main body and a lid of a reaction container and for heating a temperature of the contacting portion to a temperature higher than a heatproof temperature of the main body or the lid. Accordingly, the contacting portion between the main body and the lid of the reaction container can be heat-sealed. By heat-sealing the contacting portion between the main body and the lid of the reaction container, a sealing property of the reaction container is greatly improved, and evaporation and leakage of a reaction liquid from the reaction container can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram showing an embodiment of a gene amplification device. 
         FIG. 2  is a sectional view showing a reaction container installed in the gene amplification device in the embodiment. 
         FIG. 3  is a sectional view showing a heat lid in the embodiment. 
         FIG. 4  is a sectional view showing a state during a heat sealing operation and during gene amplification processing in the embodiment. 
     
    
    
     EMBODIMENT OF THE INVENTION 
     Hereinafter, an embodiment of a gene amplification device according to the present invention will be described with reference to  FIGS. 1 to 4 . 
     As shown in  FIG. 1 , the gene amplification device of this embodiment includes a reaction container holder  2 , a heat lid  8 , a heat lid drive mechanism  20 , and a controller  22 . A gene to be amplified is accommodated in a reaction container  14  together with a reagent, and the reaction container  14  is placed in the reaction container holder  2 . The heat lid  8  that can move up and down is provided above the reaction container holder  2 . The heat lid  8  is moved up and down by the heat lid drive mechanism  20  above the reaction container holder  2 . 
     The reaction container holder  2  is constituted by a heat transfer block  4  and a temperature control mechanism  6 . The heat transfer block  4  is provided with a plurality of container insertion parts  4   a  each consisting of a hole opened upward, and a main body  16  of the reaction container  14  is inserted into the container insertion part  4   a . The temperature control mechanism  6  is constituted by, for example, a Peltier element and has a function of raising and lowering a temperature of the heat transfer block  4 . 
     As shown in  FIG. 2 , the reaction container  14  is installed in the reaction container holder  2  in a state in which a lid  18  is attached to an upper portion of the main body  16 . A recess that fits with an upper end of the main body  16  is provided on a lower surface of the lid  18 , and the upper end of the main body  16  is fitted into the recess, thereby sealing an upper opening of the main body  16  and preventing evaporation and leakage of a reaction liquid contained in the main body  16 . In the lid  18  of the reaction container  14  shown in this embodiment, a flange  18   a  extending in a circumferential direction is provided at a lower end. The recess for fitting the upper end of the main body  16  is provided inside the flange  18 . 
     As shown in  FIG. 1 , when the reaction container  14  is installed in the container insertion part  4   a  of the reaction container holder  2 , although the main body  16  of the reaction container  14  is accommodated in the container insertion part  4   a , the lid  18  mounted on the upper portion of the main body  16  projects upward from an upper surface of the heat transfer block  4 . 
     The heat lid  8  is composed of a heat transfer block  10  and a heating mechanism  12  such as a heater for heating the heat transfer block  10 . As shown in  FIG. 3 , on a lower surface of the heat transfer block  10 , a recess  10   a  to be engaged with the lid  18  of the reaction container  14  projecting upward from the upper surface of the heat transfer block  4  is provided. When gene amplification processing is performed, the heat lid  8  is descended from above the reaction container holder  2  by the heat lid drive mechanism  20 , and the lid  18  is fitted into the recess  10   a  of the heat transfer block  10  to be in a state of  FIG. 1 . At this time, a surface  10   b  (see  FIG. 3 ) around each recess  10   a  on the lower surface of the heat transfer block  10  is in contact with an upper surface of the flange  18   a  provided on the lid  18  of the reaction container  14 . 
     Since the lid  18  of the reaction container  14  is fitted into the recess  10   a  of the heat transfer block  10  and further pressed toward the main body  16  by the heat lid  8 , as shown in  FIG. 4 , an inner surface of the recess  10   a  and an outer surface of the lid  18  are brought into close contact with each other, and the surface  10   b  around the recess  10   a  and the upper surface of the flange  18   a  are brought into close contact with each other. Thus, the lid is stably and uniformly pressed toward the reaction container holder  2 . 
     In a state shown in  FIG. 4 , a part of the heat transfer block  10  of the heat lid  8  is disposed in the vicinity of an contacting portion  30  between the main body  16  and the lid  18  indicated by a two-dot chain line circle. In this state, when the temperature of the heat transfer block  10  is raised to a temperature higher than a heatproof temperature of the main body  16  or the lid  18 , a resin of the contacting portion  30  is thermally deformed, and the main body  16  and the lid  18  are bonded and heat-sealed. A main material of the main body  16  and the lid  18  of the reaction container  14  is a resin such as polypropylene. When the main material of the main body  14  and the lid  18  is polypropylene, the heatproof temperature of the main body  14  and the lid  18  is 121° C. Therefore, when the temperature of the heat transfer block  10  is raised to a temperature higher than 121° C. (for example, 125° C.), heat sealing of the reaction container  14  can be performed. 
     The part of the heat transfer block  10  disposed in the vicinity of the contacting portion  30  of the reaction container  14  forms a heat seal part for performing heat sealing of the contacting portion  30  of the reaction container  14 . An operation of heat-sealing the reaction container  14  in this manner is called a heat sealing operation. 
     Returning to  FIG. 1 , operations of the temperature control mechanism  6  of the reaction container holder  2 , the heating mechanism  12  of the heat lid  8 , and the heat lid drive mechanism  20  are controlled by the controller  22 . The controller  22  includes a heat sealing operation part  24  and a gene amplification processing part  26 . The controller  22  can be realized by a computer dedicated to this gene amplification device or a general-purpose computer. The heat sealing operation part  24  and the gene amplification processing part  26  are functions realized by a central processing element (CPU) executing a program stored in a storage device provided in the computer that realizes the controller  22 . 
     The heat sealing operation part  24  executes the above-described heat sealing operation at a timing, for example, before executing the gene amplification processing to be described later. In the heat sealing operation, an output of the heating mechanism  12  is controlled based on a signal from a temperature sensor (not shown) attached to the heat transfer block  10  so that the temperature of the heat transfer block  10  becomes a preset temperature (for example, 125° C.) as a heat sealing operation temperature. When this heat sealing operation is executed, the operation of the temperature control mechanism  6  may be turned off. 
     The gene amplification processing part  26  starts the gene amplification processing when there is an input, from a user, to the effect that the gene amplification processing should be started. Normally, the user installs the reaction container  14  in the reaction container holder  2  and inputs the start of the gene amplification processing at a stage of closing a device cover (not shown). When the start of the gene amplification processing is input, the gene amplification processing part  26  controls the heat lid drive mechanism  20  to lower the heat lid  8  to be in the state of  FIG. 1 . 
     In a case of the conventional gene amplification device, the temperature control mechanism  6  is controlled in this state to start the gene amplification processing for cyclically raising and lowering the temperature of the heat transfer block  4 . In this embodiment, however, since the controller  22  is provided with the heat sealing operation part, the heat sealing operation is executed before the gene amplification processing is started. By this heat sealing operation, the contacting portion  30  between the main body  16  and the lid  18  of the reaction container  14  is heat-sealed, and a sealing property of the reaction container  14  is improved. In the heat sealing operation, the lid  18  is thermally deformed by being heated to a temperature higher than its heatproof temperature, but there is no influence on the reaction liquid in the main body  16 . 
     Note that, in the embodiment described above, the part of the heat lid  8  (the heat transfer block  10 ) forms the heat seal part, but the heat seal part may be provided separately from the heat lid  8 . In short, a heat seal part can be realized near the contacting portion  30  (see  FIG. 4 ) between the main body  16  and the lid  18  of the reaction container  14  installed in the reaction container holder  2 , as long as the contacting portion  30  can be heated to a temperature higher than the heatproof temperature of the main body  16  or the lid  18 . However, when the heat transfer member  4  of the reaction container holder  2  is heated to a temperature higher than the heatproof temperature of the reaction container  14 , there are problems such as evaporation of the reaction liquid and thermal deformation of the main body  16 . Thus, it is not possible to realize a heat seal part while a structure of the conventional gene amplification device is maintained. 
     DESCRIPTION OF REFERENCE SIGNS 
       2 : Reaction container holder 
       4 ,  10 : Heat transfer block 
       6 : Temperature control mechanism 
       8 : Heat lid 
       10   a : Recess 
       12 : Heating mechanism 
       14 : Reaction container 
       16 : Main body 
       18 : Lid 
       20 : Heat lid drive mechanism 
       22 : Controller 
       24 : Heat sealing operation part 
       26 : Gene amplification processing part 
       30 : Contacting portion