Multi-capillary electrophoresis apparatus

Abstract

Errors upon analysis caused by, fluctuation in electrophoresis time among plural capillaries in a multi-capillary electrophoresis apparatus is reduced. The multi-capillary electrophoresis apparatus contains a multi-capillary array that has an isolation medium filled therein for isolating a sample, has a sample injecting end on one end thereof, and has, at a position remote from the sample injecting end, a detector part for acquiring information depending on the sample, a voltage applying part for applying a voltage to an electrification path containing the sample injecting end and the detector part, a thermostat oven containing all or a part of the multi-capillary array except for the sample injecting end, a buffer container containing a buffer solution, in which the sample injecting end is immersed, and a temperature controlling part for controlling a temperature of the buffer solution.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a multi-capillary electrophoresis apparatus having a multi-capillary array formed with plural capillaries each having a sample and an isolation medium filled therein, and more particularly, to an apparatus that can suppress measurement fluctuation upon analysis with a multi-capillary electrophoresis apparatus.

[0002] In recent years, a capillary electrophoresis apparatus having a capillary having an electrophoretic medium (isolation medium) filled therein, such as a high-polymer gel and a polymer solution, has been developed as shown in Japanese Laid-open Patent Publication JP-A 6-138037. A capillary electrophoresis apparatus has high heat dissipation capacity and can be applied with a high voltage, in comparison to the conventional slab gel electrophoresis apparatus, and therefore, it has such an advantage that electrophoresis can be carried out at a high rate.

[0003] FIG. 11 shows a schematic structure of an ordinary capillary electrophoresis apparatus. As shown in FIG. 11, the capillary electrophoresis apparatus B has a capillary part 103, a thermostat oven 105, a detector part 107 and a buffer container 111.

[0004] The capillary part 103 is formed with plural capillaries 103a. The buffer container 111 is filled with a buffer solution 111a. A sample and an isolation medium for isolating the sample are filled in the capillary 103a. One end 103b of the capillary 103a is immersed in the buffer solution 111a. The other end 103c of the capillary 103a is also immersed in, for example, a buffer solution.

[0005] The detector part 107 is retained with a retaining part 107b for retaining the capillaries 103a. The detector part 107 is housed in the retaining part 107b and a cover member 108. A high voltage is applied between the end 103b and the other end 103c of the capillary 103a, whereby the sample is electrophoresed in the isolation medium. The sample thus isolated by electrophoresis is detected in the detector part 107 with an optical means. The retaining part 107b has a window part 107c for taking out fluorescence excited by the optical means.

[0006] In the capillary electrophoresis apparatus, Joule heat is generated upon applying a high voltage between the both ends 103b and 103c of the capillary 103a. In particular, air dissolved in the liquid of the isolation medium forms bubbles upon local increase of the temperature to rise the resistance of the isolation medium. When the isolation medium has high resistance, the electrophoresis migration velocity is lowered to cause adverse affects, such as deterioration in resolution power of the sample. In general, in order to prevent local generation of heat in the capillaries 103a, it has been widely operated that the capillaries 103a are placed in the thermostat oven 105, whereby the electrophoresis is carried out under the conditions where the temperature is maintained constant.

[0007] However, it is actually difficult to place the entire length of the capillaries in the thermostat oven. For example, the end 103b forming a sample injecting end for injecting the sample and the detector part 107 for detecting the sample with an optical means are not placed in the thermostat oven 105.

[0008] The sample injecting end 103b is difficult to be placed in the thermostat oven because maintenance is necessary for injecting the sample from the sample injecting end 103b. Furthermore, the ends 103b and 103c of the capillary 103a are immersed in the buffer solution 111a for electrophoresis. Therefore, it has been difficult to place the ends 103b and 103c and the vicinity of the detector part 107 in the thermostat oven 105 that contains the central part of the capillaries (electrophoresis part).

[0009] In a multi-capillary apparatus having plural capillaries, the temperature of the isolation medium in the radial direction of the capillaries are liable to be fluctuated among the plural capillaries. In particular, it is often the case that the temperature is different between the capillaries arranged in the periphery and the capillaries arranged in the central part. It is considered that this is because the capillaries arranged in the periphery are liable to be affected by the outside air.

[0010] The temperature of the isolation medium in the capillaries at the sample injecting end 103b and a detecting part 103d is liable to be differentiated from the temperature thereof inside the thermostat oven 105, and therefore, there is a possibility that the electrophoresis time is fluctuated.

[0011] A light emission part emitting, for example, laser light to the detector part 107 is provided, and a CCD image sensor (or a CCD camera having the same) is also provided for receiving the laser light incident on the detecting part 103d. Thermal noise of the CCD image sensor is increased by the influence of heat.

[0012] In order to reduce the thermal noise, it is necessary that the CCD image sensor arranged in the vicinity of the detector part 107 is maintained at a low temperature as much as possible. Accordingly, it is not preferred that both the detector part 107 and the CCD image sensor are placed in the thermostat oven 105.

[0013] Therefore, in the detector part 107, the temperature of the isolation medium in the radial direction of the capillaries is liable to be fluctuated among the plural capillaries.

[0014] The temperature of the isolation medium in the electrophoresis part that is maintained constant with the thermostat oven 105 is sharply decreased in the vicinity of the detector part 107. When there is temperature fluctuation in the longitudinal direction of the capillaries, there is a possibility that the electrophoresis time is fluctuated.

SUMMARY OF THE INVENTION

[0015] An object of the invention is to provide a multi-capillary electrophoresis apparatus having a multi-capillary array containing plural capillaries in that fluctuation of the temperature, particularly fluctuation of the temperature in the radial direction, is reduced, whereby errors upon analysis caused by, for example, fluctuation of the electrophoresis time are reduced.

[0016] The invention relates to, as one aspect, a multi-capillary electrophoresis apparatus containing a multi-capillary array that has an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end, a voltage applying part for applying a voltage to an electrification path containing the sample injecting end and the detector part, a thermostat oven containing all or a part of the multi-capillary array except for the sample injecting end, a buffer container containing a buffer solution, in which the sample injecting end is immersed, and a temperature controlling part for controlling a temperature of the buffer solution.

[0017] The invention also relates to, as another aspect, a multi-capillary electrophoresis apparatus containing a multi-capillary array that has an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end, a voltage applying part for applying a voltage to an electrification path containing the sample injecting end and the detector part, a thermostat oven containing all or a part of the multi-capillary array except for the detector part, and a temperature controlling part for controlling a temperature of the detector part.

[0018] The invention also relates to, still another aspect, a multi-capillary electrophoresis apparatus containing a multi-capillary array that has an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end, a voltage applying part for applying a voltage to an electrification path containing the sample injecting end and the detector part, a thermostat oven containing all or a part of the multi-capillary array except for the sample injecting end and the detector part, a buffer container containing a buffer solution, in which the sample injecting end is immersed, a temperature controlling part for controlling a temperature of the buffer solution, and a temperature controlling part for controlling a temperature of the detector part.

[0019] The temperature of the capillaries is controlled by the temperature controlling part, whereby fluctuation of the electrophoresis time in the radial direction among the plural capillaries is particularly reduced, and thus accurate analysis can be carried out for plural samples.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a diagram showing the overall structure of the multi-capillary electrophoresis apparatus according to one embodiment of the invention, and FIG. 1 also shows the structure of the temperature controlling part (E).

[0021] FIGS. 2A and 2B are diagrams showing the structure of the electrode in the multi-capillary electrophoresis apparatus according to one embodiment of the invention, and FIG. 2C is a diagram showing the structure of the capillary in the vicinity of the sample injecting end inserted in the electrode.

[0022] FIGS. 3A and 3B are diagrams showing the structures of the buffer container (A) and the temperature controlling part (A) installed therein for controlling the temperature of the buffer solution (A) in the multi-capillary electrophoresis apparatus according to one embodiment of the invention.

[0023] FIGS. 4A to 4C are diagrams showing the structure of the detector part in the multi-capillary electrophoresis apparatus according to one embodiment of the invention.

[0024] FIGS. 5A to 5C are diagrams showing the structures of the container part containing the detector part and the temperature controlling part (B) controlling the temperature of the detector part in the multi-capillary electrophoresis apparatus according to one embodiment of the invention, and also showing the arrangement of the optical means.

[0025] FIGS. 6A and 6B are diagrams showing the structure of the temperature controlling part (C) controlling the temperatures among the capillaries in the vicinity of the outlet of the thermostat oven in the multi-capillary electrophoresis apparatus according to one embodiment of the invention.

[0026] FIG. 7A is a diagram showing the structures of the gel block, the buffer container (B) having the buffer solution (B) filled therein, and the conduit connecting them in the multi-capillary electrophoresis apparatus according to one embodiment of the invention, and particularly showing the structure of the temperature controlling part (D) controlling the temperature of the conduit and the buffer container (B). FIG. 7B is a side view of the cover member of the buffer container (B).

[0027] FIG. 8 is a diagram showing the relationship between the controlling part and the respective temperature controlling parts in the multi-capillary electrophoresis apparatus according to one embodiment of the invention.

[0028] FIG. 9 is a graph showing a standard deviation of the electrophoresis time among the capillaries upon using the multi-capillary electrophoresis apparatus according to one embodiment of the invention.

[0029] FIG. 10 is a diagram showing the structure of the detector part in the multi-capillary electrophoresis apparatus according to a modified embodiment of the invention.

[0030] FIG. 11 is a diagram showing the schematic structure of an ordinary multi-capillary electrophoresis apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] As a result of earnest experimentation and investigations made by the inventors with respect to a multi-capillary electrophoresis apparatus, it has been found that fluctuation in analytical result among the capillaries of the multi-capillary array having plural capillaries can be suppressed by controlling the temperature of the buffer solution, in which the sample injecting end is immersed, with, for example, a heater.

[0032] Furthermore, it has been also found that fluctuation in analytical result among the plural capillaries can be suppressed by controlling the temperature of the detector part, particularly the temperature in the vicinity of the detecting part of the capillaries to be inspected.

[0033] A multi-capillary electrophoresis apparatus according to one embodiment of the invention will be described with reference to FIG. 1 to FIG. 9.

[0034] FIG. 1 is a diagram showing the overall structure of the multi-capillary electrophoresis apparatus according to one embodiment of the invention.

[0035] As shown in FIG. 1, the multi-capillary electrophoresis apparatus A according to one embodiment of the invention has a multi-capillary array 3 containing plural capillaries 3a installed in a container part CS in a thermostat oven 5. The multi-capillary array 3 has plural, for example, 16 capillaries 3a.

[0036] A sample 4a containing, for example, specimens of DNA molecules, and an isolation medium 4b functioning as a medium for isolating the DNA molecules in the sample 4a has been filled in the capillaries 3a. The isolation medium 4b is constituted with, for example, a polymer in a gel form (FIG. 2C).

[0037] The DNA fragment sample contained in the sample 4a can be distinguished by labeling the primer or the terminator with a fluorescent substance using the Sangar dideoxy method. The DNA fragment sample thus labeled with a fluorescent substance can be distinguished by the optical means described later.

[0038] One end of the capillary 3a constitutes an injecting end 3b for injecting the sample 4a by protruding from the bottom of the thermostat oven 5. The injecting end 3b is immersed in a buffer solution (A) 11a. The buffer solution (A) 11a is contained in a buffer container (A) 11. A electrode (A) 6a is mounted on the introducing part 3b.

[0039] The other end of the capillary 3a protrudes from the side of the thermostat oven 5, and through a detector part 1 for acquiring information depending on the sample 4a, forms an end part 3d of the capillaries by packing the plural capillaries 3a at a capillary fixing part 35. The end part 3d is connected to an upper gel block 34. The upper gel block 34 is connected to a buffer container (B) 15 having a buffer solution (B) 15a filled therein, a gel storage container 25 having a gel (isolation medium) 34c filled therein, and a syringe 31.

[0040] As shown with the broken line, a thermostat oven RH may be provided to contain at least one of the upper gel block 34, the buffer container 15 and the syringe 31.

[0041] The multi-capillary electrophoresis apparatus A according to the embodiment has at least one temperature controlling part among first to temperature controlling part (E)s TCM1 to TCM5, in addition to a temperature controlling part TCM0, which has been provided in an ordinary multi-capillary electrophoresis apparatus, for controlling the temperature of the capillaries 3a with the thermostat oven 5.

[0042] The multi-capillary electrophoresis apparatus according to the embodiment will be described in detail below with a focus on the temperature controlling parts.

[0043] The temperature controlling part (A) will be described with reference to FIGS. 1 to 3B. The end of the sample injecting end 3b of the capillary 3a is immersed in the buffer solution (A) 11a. The buffer solution (A) 11a is filled in the buffer container (A) 11. As shown in FIG. 2A, a electrode (A) 6a as an electrode on the side of the sample injecting end 3b is formed by pressing stainless-steel tubes 6a-1 made of stainless steel into a metallic plate 6a-2.

[0044] As shown in FIG. 2B, the sample injecting end 3b is inserted in the stainless-steel tubes 6a-1 to integrate the sample injecting end 3b and the electrode (A) 6a. A positive electrode of a direct current power supply 21 (FIG. 1) is connected to the electrode (A) 6a through an electrode (not shown in the figure) of the apparatus. Under the conditions where the sample injecting end 3b is inserted in the stainless-steel tubes 6a-1, the electrode (A) 6a is installed in a cover PC made with a resin. As shown in FIG. 2C, the isolation medium 4b is filled in the capillaries 3a, and the sample 4a is filled in the vicinity of the sample injecting end 3b.

[0045] As shown in FIG. 1 and FIG. 3A, the sample injecting end 3b and the electrode (A) 6a are immersed in the buffer solution (A) 11a filled in the buffer container (A) 11. The buffer solution (A) 11a is prepared with, for example, TBE (a mixed solution of tris (hydroxymethyl) aminomethane, boric acid and EDTA (ethylenediaminetetraacetic acid)) or TAPS (N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid).

[0046] The buffer container (A) 11 is installed in an adapter AD having an opening on an upper part thereof. The adapter AD has a rubber heater 12 laid on the inner bottom surface thereof.

[0047] The rubber heater 12 and the adapter AD are waterproofed by sealing with silicone rubber SG. An opening 12c is formed on an outer bottom surface 12b′ of the adapter AD. A thermistor (temperature monitor) TM is attached to the back surface of the rubber heater 12b exposed from the opening 12c, and a first cable CB1 connected to the thermistor TM. Furthermore, a second cable CB2 connected to a power supply PS for the heater and a fuse FS is attached to the back surface of the rubber heater 12b.

[0048] The temperature within the surface of the buffer container (A) 11 in contact with the rubber heater 12b can be made constant by using the rubber heater 12b. Maintenance operations, such as replacement of the heater, can be conveniently carried out by using such a structure that the buffer container (A) 11 is placed on the adapter AD lined with the rubber heater 12b.

[0049] While the rubber heater 12b is arranged in contact with the buffer container (A) 11, the term “contact” herein is not limited to such a constitution that both the members are physically and directly in contact with each other, but both the members may be, for example, in indirectly contact with each other. In other words, a sheet having a high heat conductance may be inserted between both the members. In essence, the term means that both the members are thermodynamically connected.

[0050] The temperature difference of the isolation medium 4b in the plural sample injecting ends 3b can be suppressed by using the temperature controlling part (A) TCM1.

[0051] The temperature controlling part (B) TCM2 controlling the temperature of the detector part 1 will be described with reference to FIGS. 4A to 5C.

[0052] As shown in FIGS. 4A to 4C, the multi-capillary 3 formed with plural capillaries 3a is supported by clipping between a capillary supporting part 77 made with, for example, a glass plate, and a pressing member 78. An outer periphery of the capillaries 3a is covered with a light shielding resin 51a, such as polyimide. A region that is not coated with the light shielding resin 51a is provided on the outer periphery of the capillaries 3a between the capillary supporting part 77 and the pressing member 78.

[0053] The region is irradiated with laser light L. The region is referred to as a detecting part 3c. An opening 78a is formed in the region containing the detecting part 3c in the pressing member 78. Excitation light K generated upon irradiating the sample with the laser light is radiated to the exterior through the opening 78a. The structures described herein are totally referred to as a detector part.

[0054] Fluctuation in intensity depending on the position of the laser light L incident on the capillaries 3a can be suppressed by irradiating the capillaries 3a with the laser light L from both above and beneath.

[0055] As shown in FIGS. 5A to 5C, the capillary supporting part 77 and the pressing member 78, as well as the multi-capillary 3 supported therebetween, are contained in a container part 7. The container part 7 is constituted with a main body 7a and a cover member 7b. The main body 7a and the cover member 7b are rotatablly connected with a hinge HG as a central axis.

[0056] The main body 7a has a container part (A) 7a-3, which can contain the capillary supporting part 77 and the pressing member 78, a groove (A) 7a-1 and a groove (B) 7a-2, which are connected to the container part (A) 7a-3 and extend toward both sides, and a protrusion part 7a-4, which is connected to the groove (B) 7a-2 and protrudes from the side surface of the main body. The groove (A) 7a-1, the groove (B) 7a-2 and the protrusion (A) part 7a-4 have a flat plane, on which the multi-capillary 3 can be arranged. The container part (A) 7a-3 forms a concave part that is deeper than the flat plane. An opening 7a-5 penetrating the main body 7a is formed in the concave part.

[0057] In the cover member 7b, on the other hand, a spring member SP is provided at a position corresponding to the container part (A) 7a-3. Upon closing the cover member 7b, the spring member SP presses the capillary supporting part 77, whereby the multi-capillary array 3 is strongly supported. A convex part (A) 7b-1 and a convex part (B) 7b-2 engaging with the groove (A) 7a-1 and the groove (B) 7a-2, respectively, are provided at positions corresponding to the grooves on both sides of the spring member SP. A protrusion (B) part 7b-3 extending from the convex part (B) 7b-2 is also provided at a position corresponding to the protrusion (A) part 7a-4.

[0058] In the case where the cover member 7b is closed, the protrusion part formed with the protrusion (A) part 7a-4 and the protrusion (B) part 7b-3 is contained in a concave part 35′ formed in the upper gel block 34 (FIG. 1) to connect the container part 7 and the upper gel block 34.

[0059] FIG. 5B shows such a state that the capillary supporting part 77 and the pressing member 78 are contained in the container part (A) 7a-3, and the multi-capillary array 3 is contained in the container part (A) 7a-3, the groove (A) 7a-1 and the groove (B) 7a-2. Laser devices 61 emitting laser light are provided above and beneath the main body 7a. A through hole (A) 7c-1 and a through hole (B) 7c-2 are formed, whereby laser light L reaches a position corresponding to the detecting part 3c (FIG. 4B).

[0060] Upon emitting the laser light L from the laser devices 61, the sample 4a in the detecting part 3c is irradiated with the laser light L to generate excitation light K. The excitation light K is emitted from the opening 7a-5 and detected with a photo-accepting unit, such as a CCD camera 71 having a CCD image sensor 73.

[0061] The temperature controlling part (B) TCM2 provided in the vicinity of the detector part 1 contains, for example, at least one of a rubber heater (A) 8b-1 and a rubber heater (B) 8b-2, which are attached to the surfaces of the groove (A) 7a-1 and the groove (B) 7a-2 facing the cover part 7b, respectively, and a rubber heater (C) 8a-1 and a rubber heater (D) 8a-2, which are attached to the surfaces of the protrusion (A) part 7b-1 and the protrusion (B) part 7b-2 facing the main body 7a, respectively. Furthermore, a temperature monitor 8c is provided in the vicinity of the container part (A) 7a-3. A thermal conductor sheet may be attached instead of the rubber heaters, or in alternative, a rubber heater and a thermal conductor sheet may be accumulated and attached.

[0062] Upon closing the cover part 7b, the cover part 7b and the main body 7a may be fixed with a fixing screw FS. The term “vicinity” of the detector part 1 herein means a region where the temperature of the detector part 1 can be directly or indirectly controlled. For example, the heater may be provided on an outer peripheral surface of the container part 7.

[0063] The temperature difference of the isolation medium among the capillaries of the multi-capillary array at the detector part 1 can be suppressed by the temperature controlling part (B) TCM2.

[0064] The temperature controlling part (C) TCM3 will be described with reference to FIGS. 6A and 6B. The multi-capillary 3 in the capillary containing part CS in the thermostat oven 5 is connected to the detector part 1 through the thermostat oven 5. An opening is formed on a side (outlet) of the detector part 1 in the thermostat oven 5. A concave part 5a-1 is formed on a main body 5a of the thermostat oven 5, and a convex part 5b-1 engaging with the concave part 5a-1 is formed on a cover part 5b of the thermostat oven 5. The multi-capillary array 3 is inserted in a gap formed between the concave part 5a-1 and the convex part 5b-1 formed upon closing the cover part 5b.

[0065] The temperature controlling part (C) TCM3 contains rubber heaters HS1 and HS2 attached to the surfaces of the concave part 5a-1 and the convex part 5b-1 facing each other, and a temperature monitor HS′ provided in the vicinity thereof. The rubber heater may be attached to one of the facing surfaces of the concave part 5a-1 and the convex part 5b-1. A thermal conductor sheet may be attached instead of the rubber heater, or in alternative, both of them may be accumulated and attached.

[0066] The temperature difference of the isolation medium among the capillaries of the multi-capillary array directed from the thermostat oven 5 to the detector part 1 can be suppressed by the temperature controlling part (C) TCM3.

[0067] The fourth and temperature controlling part (E) TCM4 and TCM5 will be described with reference to FIGS. 7A and 7B.

[0068] An upper gel block 34 is, for example, a block formed with an acrylic resin. A syringe 31, a gel storage container 25 and a buffer container (B) 15 are connected to the upper gel block 34. First to flow path (E)s 31a to 31e are formed in the upper gel block 34.

[0069] A fresh gel 34c is filled in the gel storage container 25. The gel storage container 25 is connected to an end of the flow path (B) 31b through a tube path (A) 34b. A first valve (check valve) V1 is provided between an end of the tube path (A) 34b and the flow path (B) 31b to allow only the flow of the gel from the gel storage container 25 toward the upper gel block 34.

[0070] The syringe 31 and the upper gel block 34 are connected at a connecting part 31′. When a pin valve PV is closed, and a plunger of the syringe 31 is withdrawn for reducing pressure, the fresh gel 34c in the gel storage container 25 is filled in the syringe 31 through the tube path (A) 34b, the flow path (B) 31b and the flow path (A) 31a. When the pin valve PV is closed, and the plunger of the syringe 31 is pressed, the gel filled in the syringe 31 can be injected into the capillaries 3a through the flow path (A) 31a, the flow path (C) 31c and the flow path (D) 31d. The gel functions as the isolation medium 4b inside the capillaries 3a. The isolation medium 4b after analysis can be discharged outside the capillaries 3a through the sample injecting end 3b of the capillaries by again charging the fresh gel by the foregoing operation.

[0071] A tube path (B) 15b is provided between the flow path (E) 31e in the upper gel block 34 and a flow path (F) 15e of a lower gel block 15c to connect them. The lower gel block 15c has a protrusion part 15c′ protruding downward. The pin valve PV for opening and shutting an end opening 15d of the flow path (F) 15e is attached to the lower gel block 15c. A tip end of the pin valve PV reaches the interior of the protrusion part 15c′. The isolation medium 4b is filled in the flow path (E) 31e in the upper gel block 34, the tube path (B) 15b, and the flow path (F) 15e in the lower gel block 15c. A buffer solution (B) 15a is filled in a buffer container (B) 15. The isolation medium 4b may be filled in the buffer container (B) 15 instead of the buffer solution. The isolation medium 4b and the buffer solution (B) 15a are in contact with each other at the end opening 15d of the flow path (F) 15e.

[0072] Upon carrying out electrophoresis, the pin valve PV is moved in the withdrawing direction (upward in the figure). A tip end 6b′ of a electrode (B) 6b is grounded. Upon opening the pin valve PV, an electrification path between the electrode (A) 6a and the electrode (B) 6b through the buffer solution 11a between the electrode (A) 6a and the sample injecting end 3b of the capillaries, the isolation medium 4b filled in the sample injecting end 3b of the capillaries, the capillaries 3a, the end part 3d of the capillaries, the flow path (E) 31e in the upper gel block 34, the tube path (B) 15b and the flow path (F) 15e in the lower gel block 15c, and the buffer solution (B) 15a between the end opening 15d of the flow path (F) 15e and the electrode (B) 6b.

[0073] Therefore, when the pin valve PV is opened, and a voltage is applied between the electrode (A) 6a and the electrode (B) 6b with the direct current power supply 21 (FIG. 1), such a voltage can be applied between both the ends of the electrification path (to be precise, the voltage is applied to the buffer solutions positioned on both ends of the isolation medium, which are filled in the electrification path). Consequently, an electric current can be ran in the isolation medium 4b filled in the capillaries 3a.

[0074] Upon opening the valve, the isolation medium 4b is filled to the electrode of the apparatus through a hole 15b′ and a hole 15b″. Therefore, an electric current can be ran in the isolation medium 4b filled in the capillaries 3a.

[0075] In the case where the gel is filled in the capillaries 3a, the pin valve PV is pressed. The electrification path formed with the isolation medium between the capillaries 3a and the electrode on the apparatus is cut off with the pin valve PV. At this time, the isolation medium can be injected from the gel storage container 25 to the capillaries 3a with the syringe 31.

[0076] As the temperature controlling part (D) TCM4, a rubber heater 36 arranged on an outer surface of the tube path (B) 15b and a temperature monitor 36b attached to the outer surface of the tube path (B) 15b exposed from an opening formed on the rubber heater 36. In alternative, it is possible to provide a rubber heater HT attached to an outer surface of the buffer container (B) 15 and a temperature monitor HT′ attached to an exposed surface of the buffer container (B) 15 exposed from an opening formed on the rubber heater HT. Both of them may be provided. A heater may also be provided on an outer surface of the upper gel block 34 or in the interior thereof.

[0077] The buffer solution (A) 11a and the buffer solution (B) 15a are prepared with, for example, TBE (a mixed solution of tris(hydroxymethyl)aminomethane, boric acid and EDTA (ethylenediaminetetraacetic acid)) or TAPS (N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid). The tube path (B) is similarly immersed in the buffer solution 15a.

[0078] The buffer solutions 11a and 15a are filled in the buffer containers 11 and 15, respectively. The electrode (A) 6a and the electrode (B) 6b are immersed in the buffer solution 11a and the buffer solution 15a, respectively. The buffer solutions 11a and 15a connect electrically between electrodes and the separation medium in the capillary.

[0079] In FIGS. 7A and 7B, an upper surface of the buffer solution (B) 15a is positioned above the end opening 15d of the flow path (F) 15e. Therefore, at least a part of the protrusion part 15c′ of the lower gel block 15c is immersed in the buffer solution (B) 15a.

[0080] The temperature difference of the isolation medium in the capillaries of the multi-capillary array in the vicinity of the buffer container (B) can be suppressed by the temperature controlling part (D) TCM4.

[0081] The temperature controlling part (E) TCM5 will be described with reference to FIG. 1. The temperature controlling part (E) TCM5 controls the temperature of at least one of the upper gel block 34, the buffer solution (B) 15a and the tube path (B) 15b. It is preferred that the temperature controlling part (E) TCM5 is constituted with a thermostat oven RH and a temperature monitor RH′ equipped therein.

[0082] The temperature difference of the isolation medium in the capillaries of the multi-capillary array in at least one region of the upper gel block 34, the buffer solution (B) 15a and the tube path (B) 15b can be suppressed by the temperature controlling part (E) TCM5.

[0083] A temperature controlling function provided in the electrophoresis apparatus A will be described with reference to FIG. 8.

[0084] A temperature controlling part 26 is provided for carrying out the entire temperature control, for example, PID control. The temperature controlling part 26 carries out the entire temperature control of the capillary electrophoresis apparatus A.

[0085] As described in the foregoing, a temperature monitor 31 is provided in the thermostat oven 5 for monitoring the temperature inside the thermostat oven 5. The temperature monitor 31 sends a signal S1 to the controlling part 26, and the controlling part 26 sends a control signal S2 controlling the temperature in the thermostat oven 5 based on the signal S1, whereby the basic temperature controlling part TCM0 is constituted.

[0086] The temperature controlling part (A) TCM1 contains the rubber heater 12b and the temperature monitor 12d. The temperature monitor 12d sends a signal S3 to the controlling part 26, and the controlling part 26 sends a control signal S4 controlling the temperature of the buffer solution (A) 11a based on the signal S3 through the rubber heater 12b.

[0087] The temperature controlling part (B) TCM2 contains the rubber heaters 8a-1 and 8a-2, the rubber heaters 8b-1 and 8b-2, and the temperature monitor 8c. The temperature monitor 8c sends a signal S5 to the controlling part 26, and the controlling part 26 sends a control signal S6 controlling the temperature of the isolation medium 4b in the vicinity of the detector part 1 (in the detecting part 3c of the capillaries) based on the signal S5.

[0088] The temperature controlling part (C) TCM3 contains the rubber heaters HS1 and HS2 and the temperature monitor HS′. The temperature monitor HS′ sends a signal S7 to the controlling part 26, and the controlling part 26 sends a control signal S8 controlling the temperature in the vicinity of the outlet of the 1 oven 5 based on the signal S7 through the rubber heaters HS1 and HS2.

[0089] The temperature controlling part (D) TCM4 contains the heater 36 and the temperature monitor 36b, and further contains the heater HT and the temperature monitor HT′, which are in contact with the outer peripheral surface of the buffer container (B) 15. The temperature monitor 36b and the temperature monitor HT′ send a signal S9 to the controlling part 26, and the controlling part 26 sends a control signal S10 controlling the temperature of the isolation medium 4b in the vicinity of the upper gel block 34 based on the signal S9 through the heaters 36 and HT.

[0090] The temperature controlling part (E) TCM5 contains the thermostat oven RH and the temperature monitor RH′ provided inside the thermostat oven RH. The temperature monitor RH′ sends a signal S11 to the controlling part 26, and the controlling part 26 sends a control signal S12 controlling the temperature of the thermostat oven RH based on the signal S11.

[0091] While the rubber heater 12b is provided in contact with the bottom surface of the buffer container (A) 11, it may be provided on the outer side surface of the buffer container (A) 11. The rubber heater 12b may be provided on one of the bottom surface and the side surface, and also may be provided both of them. Furthermore, the buffer container (A) 11 may be placed on a heater to carry out the temperature control.

[0092] The temperature controlling part 26 sends the temperature control signals S2, S4, S6, S8, S10 and S12 to the thermostat oven or the heaters based on the signals S1, S3, S5, S7, S9 and S11 sent from the temperature monitors to the controlling part 26, whereby the temperature control is accomplished. As the temperature monitor, for example, a platinum resistance thermometer and a thermocouple can be used.

[0093] As a method for temperature control, for example, the PID (proportional integral derivation) control may be used as described in the foregoing. That is, such a method can be used that the detection output from the temperature monitor is subjected to feedback to the heater and a Peltier element.

[0094] The temperature control is carried out to reduce the difference of the temperatures in the radial direction of the plural capillaries 3a (i.e., the temperatures of the isolation medium in the capillaries at the positions that are distant from the ends thereof by the same distance). For example, when the temperature measured by the temperature monitor 31 attached to the thermostat oven 5 and the temperatures of the other parts are controlled to reduce the difference therefrom, there is such a tendency that the temperature difference in the radial direction is reduced.

[0095] A method for using the multi-capillary electrophoresis apparatus A (i.e., a method for analyzing a sample) will be briefly described below.

[0096] The isolation medium 4b is filled in the capillaries 3a by using the syringe 31. For example, 16 capillaries 3a are used. Subsequently, a sample 4a containing plural kinds of DNA molecules having different base lengths (DNA fragment sample) is introduced to the isolation medium 4b filled in the capillaries 3a through the side of the sample injecting end 3b. The sample injecting end 3b is immersed in the buffer solution (A) 1a filled in the buffer container (A) 11. The PID control is carried out with the temperature controlling part 26 to reduce the temperature difference among the plural capillaries 3a.

[0097] The temperature control is carried out to reduce the temperature difference in the radial direction of the plural capillaries 3a by using at least one of the temperature controlling parts (A) to (E). Under the continued temperature control, a high voltage, for example, about from 10 to 20 kV, is applied between the electrode (A) 6a (cathode) and the electrode (B) 6b (anode) with the direct current power supply 21.

[0098] The DNA molecules migrate toward the electrode (B) 6b (electrophoresed) because they are negatively filled. Differences in electrophoresis migration velocity of the DNA molecules occur corresponding to the base lengths thereof. The molecules having smaller base lengths exhibit larger electrophoresis migration velocities to require shorter periods of time to reach the detecting part 3c. Upon irradiating the sample (DNA molecules) reaching the detecting part 3c with laser light L, identification markers attached to the DNA molecules are excited to cause fluorescence. The fluorescence is subjected to photoelectric transfer with a photo acceptance unit (CCD image sensor) provided in a CCD camera 71. The DNA molecules can be distinguished by electric signals obtained from the CCD camera 71, and thus the species of DNA can be distinguished. Consequently, a sample containing DNA fragments is subjected to electrophoresis, and fluorescence from the sample is detected in the course of electrophoresis, whereby the DNA base sequencing can be carried out for determining the base sequence.

[0099] The isolation medium 4b and the sample 4a can be discharged to the outside through the path 31e as described in the foregoing. It is preferred that the isolation medium 4b is replaced per analysis of one sample, and a fresh isolation medium 4b is used for analysis of a new sample.

[0100] FIG. 9 shows standard deviations of electrophoresis time in the case where 16 capillaries 3a are used, in which a sample is injected, and the capillaries are simultaneously subjected to electrophoresis under the same conditions. The data shown in FIG. 9 are experimental results in the case where the temperature controlling part (A) TCM1 and the temperature controlling part (B) TCM2 are attached to the buffer container (A) 11 and the detector part 1, respectively.

[0101] In the case where no temperature controlling part is provided on the buffer container (A) 11 and the detector part 1 (i.e., an ordinary electrophoresis apparatus), the standard deviation of electrophoresis time among the 16 capillaries 3a is about 0.62. On the other hand, in the case where only the temperature controlling part (A) TCM1 is provided, the standard deviation of electrophoresis time of the 16 capillaries 3a is about 0.16. In the case where only the temperature controlling part (B) TCM2 is provided, the standard deviation of electrophoresis time of the 16 capillaries 3a is about 0.13. In the case where both the temperature controlling part (A) TCM1 and the temperature controlling part (B) TCM2 are provided, the standard deviation of electrophoresis time of the 16 capillaries 3a is about 0.13.

[0102] It can be understood from the results that the difference of the electrophoresis time among the 16 capillaries can be reduced by providing the temperature controlling part on one of the buffer container (A) 11 and the detector part 1 for carrying out temperature control.

[0103] A multi-capillary electrophoresis apparatus according to a modified embodiment of the invention will be described with reference to FIG. 10. FIG. 10 is a cross sectional view showing the structure of the detector part 1 of the multi-capillary electrophoresis apparatus.

[0104] As shown in FIG. 10, in the detector part 1 of the multi-capillary electrophoresis apparatus according to the modified embodiment, a pressing plate 78 and a good thermal conductor 7d, such as Al, covering at least a part of the outer side surface of the pressing plate 78 are provided on the side opposite to a capillary supporting part 77 with the capillaries 3a being inserted therebetween. A Peltier element 81 is attached in contact with the outer peripheral surface of the good thermal conductor 7d. The other constitutions than those noted herein are the same as in the multi-capillary electrophoresis apparatus described in the foregoing.

[0105] The Peltier element 81 is connected to a direct current power supply 91. More specifically, the Peltier element 81 has an n-type semiconductor layer 81a, a p-type semiconductor layer 81b, an electrode 81d that is formed on one surface of the n-type semiconductor layer 81a and is connected to a negative electrode of a variable direct current power supply 91 capable of changing the output voltage, an electrode 81c that is formed on one surface of the p-type semiconductor layer 81b and is connected to a positive electrode of the variable direct current power supply 91, and a common electrode 81e that is formed on the surfaces of the n-type semiconductor layer 81a and the p-type semiconductor layer 81b opposite to the one surfaces thereof and is commonly connected to both the semiconductor layers 81a and 81b.

[0106] A good thermal conductor 75 is formed in contact with a CCD image sensor 73. The CCD image sensor 73 and the common electrode 81e carry out mutual heat exchange through the good thermal conductor 75. A temperature monitor is provided on the good thermal conductor 75. An electric signal based on the temperature measured by the temperature monitor is sent to the controlling part 26 (FIG. 1). The controlling part 26 sends a control signal for determining the voltage to be applied based on the electric signal to the variable direct current power supply 91.

[0107] In the case where the temperature measured by the temperature monitor 8a′ is too low, for example, the controlling part 26 sends such a signal to the variable direct current power supply 91 that the voltage applied to the Peltier element 81 is increased. Upon increasing the voltage applied to the Peltier element 81, the temperature on the side of the electrode 81c and the electrode 81d is increased, and therefore, the temperature of the capillaries 3a is increased. On the other hand, the temperature of the electrode 81e is decreased, and thus the CCD solid image pickup element 73 can be cooled through the good thermal conductor 75. Accordingly, the noise of the CCD solid image pickup element 73 can be reduced.

[0108] The invention has been described with reference to the specific embodiments, but the invention is not construed as being limited thereto. It is apparent to a skilled person in the art that other various changes, improvements and combinations can be applied to the invention without deviating from the spirit thereof.

[0109] According to the multi-capillary electrophoresis apparatus of the invention, fluctuation of the electrophoresis migration velocity in the radial direction of plural capillaries can be suppressed.

[0110] Therefore, analysis of a sample can be carried out in a more accurate manner by using the multi-capillary electrophoresis apparatus.

Claims

1. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array except for the sample injecting end;

a buffer container containing a buffer solution, in which the sample injecting end is immersed; and

a temperature controlling part for controlling a temperature of the buffer solution.

2. A multi-capillary electrophoresis apparatus as claimed in claim 1, wherein the temperature controlling part comprises a heater in contact with the buffer container.

3. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array except for the detector part; and

a temperature controlling part for controlling a temperature of the detector part.

4. A multi-capillary electrophoresis apparatus as claimed in claim 3, wherein the temperature controlling part comprises a heater arranged in a vicinity of the detector part.

5. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array except for the sample injecting end and the detector part;

a buffer container containing a buffer solution, in which the sample injecting end is immersed;

a first temperature controlling part for controlling a temperature of the buffer solution; and

a second temperature controlling part for controlling a temperature of the detector part.

6. A multi-capillary electrophoresis apparatus as claimed in claim 5,

wherein the first temperature controlling part comprises a first heater for heating the buffer solution and a first sensor for measuring a temperature of the buffer solution; and

the second temperature controlling part comprises a heater for heating the detector part and a second sensor for measuring a temperature of the detector part.

7. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array except for the detector part; and

a temperature controlling part for controlling a temperature in a vicinity of an outlet of the thermostat oven on a side of the detector part.

8. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array;

a gel block arranged outside the thermostat oven and charging the isolation medium in the capillary array; and

a temperature controlling part for controlling a temperature of the gel block.

9. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array; a flow path connected to the multi-capillary array and having the isolation medium filled therein; and

a temperature controlling part for controlling a temperature of the flow path.

10. A multi-capillary electrophoresis apparatus comprising:

a multi-capillary array having an isolation medium filled therein for isolating a sample, a sample injecting end on one end thereof, and a detector part for acquiring information depending on the sample at a position remote from the sample injecting end;

a voltage applying part for applying a voltage to an electrification path comprising the sample injecting end and the detector part;

a thermostat oven containing all or a part of the multi-capillary array;

a flow path connected to the multi-capillary array and having the isolation medium filled therein;

a buffer container containing a buffer solution, in which the flow path is immersed; and

a temperature controlling part for controlling a temperature of the buffer solution.

11. A multi-capillary electrophoresis apparatus as claimed in claim 10, wherein the temperature controlling part comprises a heater in contact with the buffer container.

12. A multi-capillary electrophoresis apparatus as claimed in claim 1, wherein the detector part comprises a photo accepting unit receiving excitation light generated upon irradiating the sample with laser light, and a Peltier element cooling the photo acceptance unit or heating the detector part.