Plasmid DNA filter paper elution assembly, automatic microfluidic system and elution method

Abstract

The invention relates to the field of plasmid DNA filter paper elution, in particular to a plasmid DNA filter paper elution assembly, an automatic micro-fluidic system and an elution method.By setting the flow direction, the flow velocity and the flow of eluent of a corresponding elution chip, plasmid DNA filter paper placed in an elution cavity is eluted according to a set step program, plasmid DNA dissolution and diffusion are accelerated through step-by-step ultrasound, and the elution efficiency is improved. The method combines a plasmid DNA filter paper drying, transporting and storing technology with a microfluidic technology by matching with a mode that an injection pump pumps quantitative new eluant to replace the eluant in the elution cavity, has the advantages of no tedious centrifugation step, simple structure, simplicity and convenience in operation, labor saving, standardization of the plasmid DNA filter paper elution process, adaptation to the rapid experiment requirement of a laboratory, and true realization of high efficiency and high efficiency. And eluting the high-quality plasmid DNA by using filter paper.

Description

Technical Field

[0001] The present application relates to the technical field of plasmid DNA filter paper elution, and in particular to a plasmid DNA filter paper elution component, an automatic microfluidic system and an elution method. Background Art

[0002] In order to safely transport and preserve the stability of plasmid DNA, the scientific community widely uses dot-film mailing for the transportation of plasmid DNA internationally, that is, draw a circle with a diameter of 0.2cm-0.4cm on sterile filter paper with a pencil, dot a certain volume of plasmid DNA in the circle, and place it in a ziplock bag after natural air drying. After receiving the sample, the researcher cuts off the circled filter paper, puts it in a sample tube, adds a certain amount of TE solution or double distilled water to dissolve it, and stands at room temperature for 30 minutes to dissolve it, then centrifuges it and absorbs the supernatant solution for subsequent experiments.

[0003] Since plasmid DNA is carried by filter paper, the environmental temperature and time are variable during the mailing process, and plasmid DNA is degraded to a certain extent, and there is a problem of incomplete elution. After receiving the filter paper, researchers generally use elution solution to soak the filter paper in the sample tube, let it stand at room temperature for 30 minutes, and then centrifuge it to absorb the supernatant plasmid DNA liquid. Since the plasmid DNA moves from the high concentration area to the low concentration area from the micropores of the filter paper by natural dissolution and diffusion methods such as van der Waals force in the static state, the plasmid DNA cannot be completely eluted from the filter paper by absorbing the upper liquid, resulting in low recovery efficiency, especially for the original trace amount of plasmid DNA samples, which is likely to affect the subsequent experiments. At the same time, the manual sample addition and static elution time is too long, and the experimental operation cannot be standardized. In addition, the state of the filter paper in the sample tube is different. In order to be completely immersed in the elution solution, the filter paper needs to be folded and squeezed, which causes physical and mechanical damage to the plasmid DNA and causes the DNA ring of the plasmid DNA to break.

[0004] In summary, the current plasmid DNA filter paper static immersion elution method has the disadvantages of low plasmid DNA recovery rate, long elution time, non-standardized operation and mechanical damage. Summary of the invention

[0005] The embodiments of the present application provide a plasmid DNA filter paper elution component, an automatic microfluidic system and an elution method, which are used to solve the technical problems of low plasmid DNA recovery rate, long elution time, non-standard operation and mechanical damage in the current plasmid DNA filter paper static immersion elution method.

[0006] To this end, according to one aspect of the present application, a plasmid DNA filter paper elution component is provided, comprising: An elution chip, comprising a chip body and a closing cover, wherein the chip body is provided with an elution cavity and three liquid inlet channels and three liquid outlet channels connected to the elution cavity, the upper surface of the chip body is provided with an opening, three liquid inlets and one liquid outlet, the opening is correspondingly connected to the elution cavity and is used to place filter paper containing plasmid DNA, the closing cover is used to seal the opening, the three liquid inlets are respectively connected to one end of the three liquid inlet channels away from the elution cavity, and the liquid outlet is connected to one end of the three liquid outlet channels away from the elution cavity; The chip carrier has a positioning groove on the top for placing the elution chip, and a through hole is provided at the bottom of the positioning groove, which passes through the chip carrier from top to bottom. After the elution chip is placed in the positioning groove, the elution chamber is located above the through hole; and The ultrasonic vibration mechanism comprises a water bag and an ultrasonic probe arranged in the water bag, wherein the water bag extends into the positioning groove through the through hole, and the water bag is used to fit the position of the chip body corresponding to the elution cavity.

[0007] Optionally, the chip body includes a bottom sealing plate and a substrate that are bonded to each other, the elution chamber, the three liquid inlet channels and the three liquid outlet channels are all arranged between the bottom sealing plate and the substrate, and the opening, the three liquid inlets and the one liquid outlet are all arranged on the side of the substrate away from the bottom sealing plate.

[0008] Optionally, the aperture of the through hole gradually decreases from an end away from the positioning groove to an end close to the positioning groove, and the water bag is in a truncated cone shape that matches the shape of the through hole.

[0009] Optionally, the ultrasonic vibration mechanism also includes a water cooling unit, the interior of the water bag is filled with water, and a water inlet joint and a water outlet joint are provided on the water bag. The water inlet joint and the water outlet joint are respectively connected to the water outlet and water inlet of the water cooling unit through water pipes, and the water cooling unit cools down the water in the water bag by water circulation.

[0010] Optionally, the elution chamber has relatively arranged planar chamber walls and curved chamber walls protruding away from the planar chamber walls, three of the liquid inlet flow channels are connected to the planar chamber walls, three of the liquid outlet flow channels are connected to the curved chamber walls, one of the liquid inlet flow channels is connected to the elution chamber in a direction perpendicular to the planar chamber walls, and the other two liquid inlet flow channels are connected to the elution chamber in directions perpendicular to each other, and the directions in which the three liquid inlet flow channels are connected to the elution chamber intersect at the center of the elution chamber.

[0011] Optionally, the closing cover includes a cover body, a plunger and a silicone coating, wherein the plunger is arranged on one side of the cover body, and the diameter of the plunger is smaller than the diameter of the cover body, the silicone coating is arranged on a side of the cover body facing the plunger and surrounds the plunger, the plunger is used to seal the opening, and the silicone coating is used to contact the periphery of the opening to perform a sealing effect.

[0012] According to another aspect of the present application, an automatic microfluidic system is provided, comprising three eluent sample tubes, an eluent collection tube, a syringe pump, a touch-type industrial computer, and the plasmid DNA filter paper elution assembly as described above; The three liquid inlets correspond to the three eluent sample tubes one by one and are connected through liquid inlet capillaries, and the liquid outlet is connected to the eluent collecting tube through a liquid outlet capillary; the injection pump is used to pump sterile-filtered air into the three eluent sample tubes to increase the air pressure in the eluent sample tubes so as to pump the eluent in the eluent sample tubes into the elution cavity and then flow into the eluent collecting tube, and the touch-type industrial control computer is electrically connected to the injection pump and the ultrasonic probe.

[0013] Optionally, the eluent sample tube includes a tube body and a tube cover detachably disposed on the tube body, one end of the liquid inlet capillary away from the liquid inlet passes through the tube cover and extends to the bottom of the tube body, the output port of the injection pump is connected to one end of the gas supply capillary, the other end of the gas supply capillary passes through the tube cover and extends to the top of the tube body, the injection pump pumps out sterile filtered air and transmits it to the eluent sample tube through the gas supply capillary, thereby increasing the air pressure in the eluent sample tube and pumping the eluent into the elution chip through the liquid inlet capillary. In the final stage of the elution procedure, the injection pump continuously pumps out sterile air and uses the air to displace the liquid in the liquid inlet channel, the elution chamber and the liquid outlet channel into the eluent collection tube.

[0014] Optionally, the automatic microfluidic system also includes a chassis, a sample tube support, a collection tube support and a capping mechanism. A mounting hole is provided on the top of the chassis, the chip support is arranged on the mounting hole, the ultrasonic vibration mechanism and the injection pump are both arranged in the chassis, the sample tube support is arranged on one side of the chassis, the three eluent sample tubes are installed on the sample tube support, the touch-type industrial computer is arranged on the other side of the chassis, the collection tube support is arranged on the top of the chassis, the eluent collection tube is installed on the collection tube support, the capping mechanism is arranged on the top of the chassis and is located above the chip support, and the capping mechanism is used to apply pressure to the closing cover of the elution chip placed on the chip support to fix the elution chip in the positioning groove.

[0015] According to another aspect of the present application, there is provided an elution method, using the automatic microfluidic system as described above, the elution method comprising the following steps: S1. Load the elution chip into the positioning groove on the chip carrier, remove the closing cover, place the plasmid DNA filter paper horizontally into the elution chamber through the opening, seal the opening with the closing cover, install the eluent collection tube and the three eluent sample tubes with eluent in place, and connect the inlet capillary, the outlet capillary and the injection pump; S2. Set the running program through the touch-type industrial computer, click Start to start the running program, the syringe pump pumps sterile air into the three eluent sample tubes, pushes the set amount of eluent into the elution chip and fills the elution cavity; S3. Start the ultrasonic vibration mechanism, the ultrasonic probe emits an ultrasonic wave of a set power for 4 seconds, and then stops; S4. The syringe pump pumps sterile air into the three eluent sample tubes to push one third of the remaining eluent in the eluent sample tubes into the elution chamber; S5. Start the ultrasonic vibration mechanism, the ultrasonic probe emits an ultrasonic wave of a set power for 4 seconds, and then stops; S6. The syringe pump pumps sterile air into the three eluent sample tubes to push one-half of the remaining eluent in the eluent sample tubes into the elution chamber; S7. Start the ultrasonic vibration mechanism, the ultrasonic probe emits an ultrasonic wave of a set power for 4 seconds, and then stops; S8. The injection pump pumps sterile air into the three eluent sample tubes to push the remaining eluent in the eluent sample tubes into the elution chamber, and then the injection pump continues to run for 10 seconds until all the liquid in the inlet channel, the elution chamber and the outlet channel are pushed into the eluent collection tube, completing the plasmid DNA filter paper elution process.

[0016] The plasmid DNA filter paper elution component, automatic microfluidic system and elution method provided by the present application have the following beneficial effects: 1. Plasmid DNA elution is completed inside the sealed elution chip to avoid environmental pollution; 2. With the ultrasonic vibration mechanism, the plasmid DNA filter paper is thoroughly eluted, the recovery rate is high, the mechanical damage is small, and the elution time is short; 3. Use gradual ultrasound to accelerate the dissolution and diffusion of plasmid DNA, and use a syringe pump to pump in a quantitative new eluent to replace the eluent in the elution chamber, thereby combining the plasmid DNA filter paper drying, transportation and storage technology with microfluidic technology. There are no cumbersome centrifugation steps, the structure is simple, the operation is easy, labor-saving, and the plasmid DNA filter paper elution process is standardized, which meets the needs of rapid laboratory experiments and truly realizes high-efficiency and high-quality plasmid DNA filter paper elution. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] in: Figure 1 It is a schematic diagram of the assembly of a plasmid DNA filter paper elution component shown in one embodiment of the present application; Figure 2 yes Figure 1 A perspective schematic diagram of a plasmid DNA filter paper elution assembly is shown; Figure 3 yes Figure 1 Exploded schematic diagram of the plasmid DNA filter paper elution assembly shown; Figure 4 It is an external schematic diagram of an elution chip in a plasmid DNA filter paper elution assembly shown in one embodiment of the present application; Figure 5 yes Figure 4 A perspective schematic diagram of the elution chip is shown; Figure 6 yes Figure 4 Exploded schematic of the elution chip shown; Figure 7 It is a schematic diagram of the structure of a sealing cover in an elution chip shown in one embodiment of the present application; Figure 8 It is an external schematic diagram of an ultrasonic vibration mechanism in a plasmid DNA filter paper elution assembly shown in one embodiment of the present application; Fig. 9 yes Figure 8 A perspective schematic diagram of an ultrasonic vibration mechanism shown; Fig.10 yes Figure 8 An exploded schematic diagram of the ultrasonic vibration mechanism shown; Fig.11 is a schematic structural diagram of an automatic microfluidic system shown in an embodiment of the present application; Fig.12 yes Fig.11 A schematic structural diagram of the automatic microfluidic system from another perspective; Fig.13 It is an external schematic diagram of an automatic microfluidic system having a chassis, a sample tube support seat and a capping mechanism according to an embodiment of the present application; Fig.14 yes Fig.13 A schematic structural diagram of the automatic microfluidic system from another perspective; Fig.15 yes Fig.13 A schematic diagram showing that the capping mechanism and the collection tube support seat in the automatic microfluidic system are in an open state; Fig.16 yes Fig.13 A top view of the automated microfluidic system shown; Fig.17 It is a structural schematic diagram of a closed state of a collection tube support seat in an automatic microfluidic system shown in an embodiment of the present application; Fig.18 It is a structural schematic diagram of the collection tube support seat in the automatic microfluidic system in an open state shown in one embodiment of the present application; Fig.19 is an exploded schematic diagram of a collection tube support seat in an automatic microfluidic system shown in an embodiment of the present application; Fig. 20 It is a partial structural schematic diagram of a capping mechanism in an automatic microfluidic system shown in an embodiment of the present application; Fig.21 yes Fig. 20 A perspective view of a portion of the capping mechanism shown; Fig. 22 yes Fig. 20 An exploded view of a portion of the gland mechanism is shown; Fig.23 is a velocity diagram of the simulated trajectory of the eluent fluid in the elution chip; Fig.24 It is a schematic diagram of a process of an elution method shown in an embodiment of the present application; Fig.25 It is a bar graph showing the concentration of each group of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid samples; Fig.26 It is a bar graph of the supercoil ratio of each group of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid samples; Fig. 27 It is a bar graph of the CV values ​​of plasmid concentrations of each group of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid samples; Fig.28 It is a bar graph showing the recovery rates of each group of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid samples.

[0019] Description of main component symbols: 1. Chassis; 2. Touch-type industrial computer; 3. Eluent sample tube; 4. Eluent collection tube; 11. elution chip; 111. bottom sealing plate; 112. substrate; 113. closing cover; 1101. liquid inlet; 1102. liquid outlet; 1103. liquid inlet channel; 1104. liquid outlet channel; 1106. elution chamber; 1131. silica gel coating; 1132. cover body; 1133. plunger; 21. Chip carrier; 22. Ultrasonic vibration mechanism; 2201. Water inlet connector; 2202. Water outlet connector; 2203. Water bag; 2204. Ultrasonic probe; 5. Covering mechanism; 50. Limiting seat; 51. Limiting track; 52. Covering long slider; 53. Thumb screw; 54. First slider limiting screw; 55. Second slider limiting screw; 56. Covering nut; 57. Connecting bolt; 6. Collection tube bearing seat; 61. Bearing frame; 62. Pillar pin; 63. Active joint plate; 64. Capillary joint; 71. Centrifugal water pump; 72. Heat dissipation module; 301. Syringe pump; 401, liquid inlet capillary; 402, liquid outlet capillary; 8011. Gas transmission capillary. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present application, the present application will be described more comprehensively with reference to the relevant drawings below. The preferred embodiments of the present application are provided in the drawings. However, the present application can be implemented in many other different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0021] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0022] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0025] It should also be noted that, in the embodiments of the present application, the same figure mark is used to represent the same component or the same part. For the same parts in the embodiments of the present application, the figure may only mark one of the parts or components as an example. It should be understood that the figure mark also applies to other identical parts or components.

[0026] It is understandable that the plasmid DNA filter paper elution assembly, automatic microfluidic system and elution method provided by the present application are used for eluting plasmid DNA filter paper. For plasmid DNA filter paper that is transported or stored in a dry state, if it is necessary to elute the plasmid DNA on the filter paper for experimental research, the plasmid DNA filter paper elution assembly, automatic microfluidic system and elution method can be used.

[0027] like Figure 1-Figure 6 and Figure 8-Figure 9As shown, the embodiment of the present application provides a plasmid DNA filter paper elution component, which includes an elution chip 11, a chip carrier 21 and an ultrasonic vibration mechanism 22. The elution chip 11 includes a chip body and a closing cover 113. An elution cavity 1106 and three liquid inlet channels 1103 and three liquid outlet channels 1104 connected to the elution cavity 1106 are provided in the chip body. An opening, three liquid inlets 1101 and one liquid outlet 1102 are provided on the upper surface of the chip body. The opening is correspondingly connected to the elution cavity 1106 and is used to place the filter paper containing plasmid DNA. The closing cover 113 is used to seal the opening. The three liquid inlets 1101 are respectively connected to one end of the three liquid inlet channels 1103 away from the elution cavity 1106 in a one-to-one correspondence. The liquid outlet 1102 is connected to one end of the three liquid outlet channels 1104 away from the elution cavity 1106. The top of the chip carrier 21 is provided with a positioning groove for placing the elution chip 11. The bottom of the positioning groove is provided with a through hole that passes through the chip carrier 21 from top to bottom. After the elution chip 11 is placed in the positioning groove, the elution cavity 1106 is located above the through hole. The ultrasonic vibration mechanism 22 includes a water bag 2203 and an ultrasonic probe 2204 disposed in the water bag 2203. The water bag 2203 extends into the positioning groove through the through hole. The water bag 2203 is used to fit the position of the chip body corresponding to the elution cavity 1106.

[0028] In the embodiment of the present application, the plasmid DNA filter paper elution component is used to elute the plasmid DNA filter paper, and the plasmid DNA elution is completed inside the sealed chip to avoid environmental pollution; at the same time, since the ultrasound applied by the ultrasonic vibration mechanism 22 accelerates the dissolution and diffusion of the plasmid DNA, the plasmid DNA filter paper is thoroughly eluted, the recovery rate is high, the mechanical damage is small, the elution time is short, and the whole process can be completed within a maximum of 3 minutes.

[0029] Furthermore, the size of the positioning groove on the chip carrier 21 is similar to that of the elution chip 11, and the positioning groove can just place the elution chip 11 horizontally. A side opening is opened at the edge of the positioning groove, and the elution chip 11 can be grabbed by hand and placed into the positioning groove or taken out from the positioning groove.

[0030] In one embodiment, if Figure 4-Figure 6 As shown, the chip body includes a bottom sealing plate 111 and a substrate 112 which are bonded to each other, an elution chamber 1106, three liquid inlet channels 1103 and three liquid outlet channels 1104 are all arranged between the bottom sealing plate 111 and the substrate 112, and an opening, three liquid inlets 1101 and one liquid outlet 1102 are all arranged on the side of the substrate 112 away from the bottom sealing plate 111.

[0031] In one embodiment, if Figure 5As shown, the elution chamber 1106 has relatively arranged planar chamber walls and arc-shaped chamber walls protruding away from the planar chamber walls, three liquid inlet channels 1103 are connected to the planar chamber walls, and three liquid outlet channels 1104 are connected to the arc-shaped chamber walls. The direction in which one of the liquid inlet channels 1103 is connected to the elution chamber 1106 is perpendicular to the planar chamber wall, and the directions in which the other two liquid inlet channels 1103 are connected to the elution chamber 1106 are perpendicular to each other. The directions in which the three liquid inlet channels 1103 are connected to the elution chamber 1106 intersect at the center of the elution chamber 1106.

[0032] Through the above arrangement, the inner surface of the cavity connected to the liquid outlet channel 1104 is in a contracted shape, which is conducive to completely pushing out all the liquid in the elution cavity 1106 with air.

[0033] like Fig.23 As shown, the simulated trajectory velocity of the eluent fluid of the elution chip 11 is shown. The eluent enters the elution chamber 1106 from the three liquid inlets 1101 through the three liquid inlet channels 1103. The eluent flow rates in the three liquid inlet channels 1103 are similar and there is no significant difference. After the eluent enters the elution chamber 1106, the eluent flow rate decreases significantly. The eluent trajectory entering the elution chamber 1106 through the upper and lower liquid inlets 1101 significantly diffuses, which is different from the eluent entering the elution chamber 1106 through the middle liquid inlet 1101. Compared with the three parallel traces, the originally concentrated traces are dispersed into three traces, which achieve full coverage of the plasmid DNA filter paper. The area of ​​the plasmid DNA filter paper that can be washed is larger than that of the three parallel traces. The inner surface of the elution chamber 1106 connected to the liquid outlet channel 1104 through three liquid inlet channels 1103 is in a contracted shape. The simulation results show that the flow rate of the eluent in the three liquid outlet channels 1104 is similar to the flow rate of the eluent in the three liquid inlet channels 1103, indicating that the flow rate of the chip inlet and outlet per unit time is equal.

[0034] In one embodiment, if Figure 2-Figure 3 As shown, the aperture of the through hole gradually decreases from the end away from the positioning groove to the end close to the positioning groove, and the water capsule 2203 is a truncated cone shape that matches the shape of the through hole. The shape of the through hole can just wrap the super-truncated cone-shaped water capsule 2203, and the top of the water capsule 2203 and the bottom of the elution chip 11 are tightly fitted at the position of the elution cavity 1106. With this design, the cooperation of the water capsule 2203 and the ultrasonic probe 2204 can better apply ultrasonic vibration to the filter paper containing plasmid DNA in the elution cavity 1106 during the elution process.

[0035] In one embodiment, if Figure 8-Figure 12As shown, the ultrasonic vibration mechanism 22 also includes a water cooling unit. The interior of the water bag 2203 is filled with water. A water inlet joint 2201 and a water outlet joint 2202 are provided on the water bag 2203. The water inlet joint 2201 and the water outlet joint 2202 are respectively connected to the water outlet and the water inlet of the water cooling unit through water pipes. The water cooling unit cools the water in the water bag 2203 by water circulation.

[0036] By providing a water cooling unit, it is possible to prevent the temperature of the ultrasonic probe 2204 from rising during operation and being transferred to the elution chip 11 through water, thereby causing deformation of the chip.

[0037] Specifically, the water cooling unit is mainly composed of a centrifugal water pump 71 and a heat dissipation module 72 (including a cooling fan, a water tank, a heat sink and an air duct). The water tank is filled with water, and the water tank is connected to the centrifugal water pump 71 through a silicone hose. The centrifugal water pump 71 is then connected to the water inlet joint 2201 on the water bag 2203 through a water pipe. The water in the water bag 2203 returns to the water tank through the water pipe connected to the water outlet joint 2202. After being air-cooled by the heat sink of the water tank, the water is pumped into the water bag 2203 through the centrifugal water pump 71 to complete the water cooling cycle.

[0038] In one embodiment, if Figure 4-Figure 7 As shown, the closing cover 113 includes a cover body 1132, a plunger 1133 and a silicone coating 1131. The plunger 1133 is arranged on one side of the cover body 1132, and the diameter of the plunger 1133 is smaller than the diameter of the cover body 1132. The silicone coating 1131 is arranged on the side of the cover body 1132 facing the plunger 1133 and surrounds the plunger 1133. The plunger 1133 is used to seal the opening, and the silicone coating 1131 is used to contact with the surrounding of the opening to perform a sealing effect.

[0039] The embodiment of the present application also provides an automatic microfluidic system, such as Figure 11-Figure 12 As shown, the automatic microfluidic system includes three eluent sample tubes 3, an eluent collection tube 4, a syringe pump 301, a touch-type industrial computer 2, and a plasmid DNA filter paper elution assembly in any of the above embodiments. The three liquid inlets 1101 correspond to the three eluent sample tubes 3 one by one and are connected through the liquid inlet capillary 401, and the liquid outlet 1102 is connected to the eluent collection tube 4 through the liquid outlet capillary 402; the syringe pump 301 is used to pump sterile filtered air into the three eluent sample tubes 3 to increase the air pressure in the eluent sample tube 3, so as to pump the eluent in the eluent sample tube 3 into the elution chamber 1106 and then flow into the eluent collection tube 4, and the touch-type industrial computer 2 is electrically connected to the syringe pump 301 and the ultrasonic probe 2204.

[0040] The eluent is a liquid having a pH value greater than or equal to 7.0 but less than 9.0.

[0041] When the automatic microfluidic system in this application is used to elute the plasmid DNA filter paper, the Fig.24 As shown, the elution method comprises the following steps: S1. Load the elution chip 11 into the positioning groove on the chip carrier 21, remove the closing cover 113, put the plasmid DNA filter paper horizontally into the elution chamber 1106 through the opening, seal the opening with the closing cover 113, install the eluent collection tube 4 and the three eluent sample tubes 3 with eluent in place, and connect the inlet capillary 401, the outlet capillary 402 and the injection pump 301; S2. Set the running program through the touch-screen industrial computer 2, click Start to start the running program, the syringe pump 301 pumps sterile air into the three eluent sample tubes 3, pushes the set amount of eluent into the elution chip 11 and fills the elution chamber 1106; S3 starts the ultrasonic vibration mechanism 22, the ultrasonic probe 2204 emits an ultrasonic wave of a set power for 4 seconds, and then stops; S4. The syringe pump 301 pumps sterile air into the three eluent sample tubes 3 to push one third of the remaining eluent in the eluent sample tube 3 into the elution chamber 1106; S5. Start the ultrasonic vibration mechanism 22, the ultrasonic probe 2204 emits an ultrasonic wave of a set power for 4 seconds, and then stops; S6. The syringe pump 301 pumps sterile air into the three eluent sample tubes 3 to push one-half of the remaining eluent in the eluent sample tube 3 into the elution chamber 1106; S7. Start the ultrasonic vibration mechanism 22, the ultrasonic probe 2204 emits an ultrasonic wave of a set power for 4 seconds, and then stops; S8. The injection pump 301 pumps sterile air into the three eluent sample tubes 3 to push the remaining eluent in the eluent sample tubes 3 into the elution chamber 1106, and then the injection pump 301 continues to run for 10 seconds until all the liquid in the inlet channel 1103, the elution chamber 1106 and the outlet channel 1104 are pushed into the eluent collection tube 4, completing the plasmid DNA filter paper elution process.

[0042] It should be noted that the method uses gradual ultrasound to accelerate the dissolution and diffusion of plasmid DNA, and cooperates with the injection pump 301 to pump in a quantitative new eluent to replace the eluent in the elution chamber 1106, thereby combining the plasmid DNA filter paper drying, transportation and storage technology with the microfluidic technology. There are no cumbersome centrifugation steps, the structure is simple, the operation is easy, labor-saving, and the plasmid DNA filter paper elution process is standardized, which meets the laboratory's rapid experimental needs and truly realizes high-efficiency and high-quality plasmid DNA filter paper elution.

[0043] In addition, by setting the flow direction, flow rate and flow rate of the elution liquid of the corresponding elution chip 11, the plasmid DNA filter paper placed in the elution chamber 1106 is eluted according to the set step program; unattended, the elution is automatically completed under the set program, saving manpower. Compared with the plasmid DNA filter paper soaking method used in general laboratories to elute plasmid DNA, the use of the elution chip 11 to elute plasmid DNA can better ensure the stability of experimental results between batches.

[0044] The touch-type industrial computer 2 is mainly composed of a liquid crystal touch screen and an industrial control module, wherein the liquid crystal touch screen is responsible for inputting control instructions and displaying data, and the industrial control module is responsible for outputting data, receiving data, processing data, and storing data. You can click on the liquid crystal touch screen, log in according to your account and password, set the program running plan, add or remove steps in the plan, and view the pressure value, flow rate, actual running time and other parameters of the injection pump 301, and form a table for viewing or transmitting to the network cloud for storage.

[0045] Specifically, the control interface of the touch-type industrial computer 2 can be logged in according to the account and password. The account has different levels of authorization levels, which correspond to the use and management permissions of the equipment that the corresponding operators can have, and can also track the use of the equipment; after logging in to the control system, you can select a program plan or create a new plan; after selecting a plan, click the OK button to enter the detailed configuration interface of the plan, in which you can set parameters for the flow rate, working time, flow rate and pressure threshold of the injection pump 301, and you can set parameters for the number of working times, working time, interval time and ultrasonic power of the ultrasonic probe 2204; the plan executes the program according to different stages, and the plan can be adjusted by adding or subtracting stages. The execution order of each stage can also be adjusted, and the working parameters of each injection pump 301 and ultrasonic probe 2204 in each stage can be adjusted.

[0046] In one embodiment, if Figure 11-Figure 12 As shown, the eluent sample tube 3 includes a tube body and a tube cover detachably arranged on the tube body, one end of the liquid inlet capillary 401 away from the liquid inlet 1101 passes through the tube cover and extends to the bottom of the tube body, the output port of the injection pump 301 is connected to one end of the gas supply capillary 8011, and the other end of the gas supply capillary 8011 passes through the tube cover and extends to the top of the tube body. The injection pump 301 pumps out sterile filtered air and transmits it to the eluent sample tube 3 through the gas supply capillary 8011, thereby increasing the air pressure in the eluent sample tube 3 and pumping the eluent into the elution chip 11 through the liquid inlet capillary 401. In the final stage of the elution procedure, the injection pump 301 continuously pumps out sterile air and uses the air to displace the liquid in the liquid inlet channel 1103, the elution chamber 1106 and the liquid outlet channel 1104 to the eluent collection tube 4.

[0047] In one embodiment, if Figure 13-Figure 16 As shown, the automatic microfluidic system also includes a chassis 1, a sample tube support seat, a collection tube support seat 6 and a capping mechanism 5. The chassis 1 is responsible for loading the various parts and assemblies of the automatic microfluidic system, providing protection for the various parts and assemblies against external physical collisions and positioning and assembling space for other necessary related auxiliary units. A mounting hole is provided on the top of the chassis 1, a chip support seat 21 is arranged on the mounting hole, an ultrasonic vibration mechanism 22 and an injection pump 301 are both arranged in the chassis 1, a sample tube support seat is arranged on one side of the chassis 1, three eluent sample tubes 3 are installed on the sample tube support seat, a touch-type industrial computer 2 is arranged on the other side of the chassis 1, a collection tube support seat 6 is arranged on the top of the chassis 1, an eluent collection tube 4 is installed on the collection tube support seat 6, a capping mechanism 5 is arranged on the top of the chassis 1 and is located above the chip support seat 21, and the capping mechanism 5 is used to apply pressure to the closing cover 113 of the elution chip 11 placed on the chip support seat 21 to fix the elution chip 11 in the positioning groove.

[0048] Specifically, the sample tube support seat is provided with three slots for inserting three eluent sample tubes 3, and the three eluent sample tubes 3 are respectively inserted and fixed in the three slots in a one-to-one correspondence.

[0049] like Figure 17-Figure 19 As shown, the collection tube support seat 6 includes a support frame 61, a pin 62, a movable joint plate 63, and a capillary joint 64. The support frame 61 and the movable joint plate 63 are rotatably connected by the pin 62. The end of the movable joint plate 63 has a perforation, and one end of the capillary joint 64 passes through the movable joint plate 63. The support frame 61 has a circular hole, which can be vertically placed in the eluent collection tube 4. One end of the capillary joint 64 passes through the movable joint plate 63 and can be inserted into the eluent collection tube 4 in a vertical state. The other end of the capillary joint 64 is connected to the liquid outlet 1102 of the elution chip 11 through the liquid outlet capillary 402. The movable joint plate 63 of the support seat can rotate around the pin 62 connected to the support frame 61, and the movable angle is horizontal from 0° to less than 120°. When the angle between the movable joint plate 63 and the horizontal plane is 0° (such as Fig.17 As shown in FIG. 1 ), one end of the capillary joint 64 passing through the movable joint plate 63 is vertically inserted into the eluent collecting tube 4. When the angle between the movable joint plate 63 and the horizontal plane is 90° (as shown in FIG. 1 ), the capillary joint 64 passes through the movable joint plate 63 and is vertically inserted into the eluent collecting tube 4. Fig.18 As shown in FIG. 6 ), one end of the capillary joint 64 passing through the movable joint plate 63 leaves the eluent collecting tube 4, and the eluent collecting tube 4 can be taken out from the circular hole of the carrier 61 for standby use.

[0050] like Fig.13 , Fig.15 , Figure 20-22As shown, the gland mechanism 5 includes a limiting seat 50 with a slot, a limiting rail 51, a gland strip slider 52, a hand screw 53 and a gland nut 56. The limiting rail 51 and the limiting seat 50 are respectively arranged on the chassis 1 on the opposite sides of the bearing seat. The gland strip slider 52 is inserted into the limiting rail 51 and can move linearly in the limiting rail 51. The limiting rail 51 can limit the gland strip slider 52 within a certain range in the X-axis direction, the Y-axis direction and the Z-axis direction of the Cartesian rectangular coordinate system. The gland strip slider 52 can move within a certain range in the X-axis direction. The gland strip slider 52 has a threaded opening on the outer section of the limiting rail 51, and the hand screw 53 is screwed in to penetrate the gland strip slider 52 from top to bottom. The corresponding bottom of the end of the hand screw 53 is connected to the gland nut 56 by a connecting bolt 57. 6. The gland nut 56 is embedded in the hexagonal groove at the corresponding position. When the hand screw 53 is turned, the gland nut 56 can move along the Z-axis direction of the Cartesian rectangular coordinate system. The bottom of the gland nut 56 can press the closing cover 113 of the elution chip 11 tightly, and pressure is applied to the closing cover 113 to achieve sealing of the elution chamber 1106. A through long groove is opened on the side of the limiting track 51. The first slider limiting screw 54 and the second slider limiting screw 55 pass through the long groove and are connected to the side of the gland long slider 52. Through these two limiting screws, the gland long slider 52 can be moved along the X-axis direction of the Cartesian rectangular coordinate system. The end of the gland long slider 52 close to the hand screw 53 can be inserted into the notch of the limiting seat 50 to achieve the limitation of the gland long slider 52 in the X-axis direction, the Y-axis direction and the Z-axis direction of the Cartesian rectangular coordinate system.

[0051] Example The fast 101 type, medium 102 type and slow 103 type filter papers were used to carry two plasmid DNAs, and then the elution chip 11 in the embodiment of the present application and the immersion method commonly used in general laboratories were used to elute the plasmid DNA. The two plasmid DNAs were pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201, with lengths of 6712bp and 11472bp, respectively. The operation steps of eluting plasmid DNA by filter paper immersion method are as follows: draw a circle with a diameter of 0.4cm on the sterilized filter paper with a pencil, dot 500μL of plasmid DNA in the circle, place it in a ziplock bag after natural air drying, cut off the circled filter paper after 72 hours, place it in a 1.5mL sample tube, add 500μL of TE solution to dissolve it, stand it at room temperature for 30 minutes, centrifuge it at 10,000rpm for 5 minutes, and then absorb the supernatant solution for subsequent detection experiments.

[0052] The concentration, A260 / A280 purity and supercoiling ratio of the chip eluate, filter paper soaking solution and plasmid DNA stock solution were detected by agarose electrophoresis. The recovery rate was calculated by the ratio of the chip eluate, filter paper soaking solution and plasmid DNA stock solution, and the coefficient of variation between each sample batch was calculated by (standard deviation ÷ mean) × 100% = CV; the values ​​were retained to three decimal places and expressed as mean ± standard deviation, i.e., mean ± SD. SPSS11.0 was used for data analysis, and one-way analysis of variance was used for comparison between groups.

[0053] like Fig.25 As shown, the comparison of the concentrations of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA samples in each group showed that when the filter paper model was fast 101, there were significant differences in the concentrations of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA eluted by chip elution and immersion method, P<0.05, and the plasmid DNA concentrations of the chip elution solution of the two plasmid DNAs were 1.825 times and 1.949 times the concentration of the filter paper immersion solution, respectively; when the filter paper model was medium speed 102, there were significant differences in the concentrations of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA eluted by chip elution and immersion method, P<0.05, and the chip elution of the two plasmid DNAs The plasmid DNA concentrations of the chip elution solution were 1.839 times and 1.942 times of the concentration of the filter paper soaking solution, respectively; the filter paper model was slow 103 type, and there were significant differences in the concentration values ​​of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA eluted by chip elution and immersion method, P<0.05, and the plasmid DNA concentrations of the chip elution solution of the two plasmid DNAs were 2.002 times and 2.164 times of the concentration of the filter paper soaking solution, respectively; the concentration comparison results showed that whether it was a plasmid DNA with a molecular weight less than 10,000 bp or a plasmid DNA greater than 10,000 bp, the elution of plasmid DNA using the elution chip 11 in combination with the automatic microfluidic system could obtain a concentration that was almost the same as that of the plasmid DNA stock solution, while the elution of filter paper by the immersion method had the disadvantage of low elution concentration, which showed the high efficiency of the elution chip 11.

[0054] like Fig.26As shown in the figure, the supercoiling ratio of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA samples in each group was compared. The filter paper model was fast 101. There was a significant difference in the supercoiling ratio of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA eluted by chip elution and soaking method, P<0.05. The supercoiling ratio of the two plasmid DNA samples was significantly different. The supercoil ratios of plasmid DNA in the chip elution solution of the filter paper soaking solution were 1.245 times and 1.291 times of those in the filter paper soaking solution, respectively. The filter paper model was medium-speed 102 type. There were significant differences in the supercoil ratios of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA eluted by chip elution and soaking method, P<0.05. The supercoil ratios of plasmid DNA in the chip elution solution of the two plasmid DNAs were 1.245 times and 1.291 times of those in the filter paper soaking solution, respectively. 1.305 times and 1.360 times; the filter paper model was slow 103 type, and there was a significant difference in the supercoiling ratios of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA eluted by chip elution and immersion method, P<0.05, and the supercoiling ratios of plasmid DNA in the chip elution solution of the two plasmid DNAs were 1.400 times and 1.414 times that of the filter paper immersion solution, respectively; the comparison results of the supercoiling ratios showed that whether it was a plasmid DNA with a molecular weight less than 10,000 bp or a plasmid DNA greater than 10,000 bp, the supercoiling ratio of plasmid DNA elution using elution chip 11 combined with an automatic microfluidic system could be obtained, which was almost the same as that of the plasmid DNA stock solution, while the filter paper immersion method showed a trend of decreasing supercoiling ratios to varying degrees, suggesting that the immersion method for eluting plasmid DNA caused certain mechanical damage to the plasmid DNA, and the comparison results showed the high efficiency of elution chip 11.

[0055] like Fig. 27As shown, the comparison of the CV values ​​of each group of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA samples showed that the filter paper model was fast 101, pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA were eluted by chip elution and immersion method, and the CV values ​​of the filter paper immersion solution were 9.633 times and 4.297 times of the chip elution solution of the two plasmid DNAs, respectively; the comparison of the CV values ​​of each group of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA samples showed that the filter paper model was medium speed 102, pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA were eluted by chip elution and immersion method The CV values ​​of the filter paper soaking solution were 5.406 times and 5.336 times of those of the chip elution solution of the two plasmid DNAs, respectively; the comparison of the CV values ​​of the pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA samples in each group showed that the filter paper model was slow 103 type, and pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA were eluted by chip elution and soaking method, and the CV values ​​of the filter paper soaking solution were 4.084 times and 7.120 times of those of the chip elution solution of the two plasmid DNAs, respectively; this comparison result suggests that the CV value of the soaking method is larger and the batch-to-batch variation coefficient is larger, indicating that manual operation to elute plasmid DNA cannot be standardized and consistent, while the chip elution shows a small batch-to-batch variation coefficient, and the quality consistency of the plasmid DNA eluted by the automatic microfluidic system is very good.

[0056] like Fig.28As shown in the figure, the recovery rates of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA samples in each group were compared. When the filter paper model was fast 101, there was a significant difference in the recovery rates of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA using chip elution and soaking method elution, P<0.05. The plasmid DNA recovery rates of the chip elution solution of the two plasmid DNAs were 1.825 times and 1.949 times that of the filter paper soaking solution, respectively. When the filter paper model was medium speed 102, there was a significant difference in the recovery rates of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA using chip elution and soaking method elution, P<0.05. The plasmid DNA recovery rates of the chip elution solution of the two plasmid DNAs were The yields were 1.839 times and 1.942 times that of the filter paper soaking solution, respectively; the filter paper model was slow 103 type, and the recovery rates of pET28b-T7-6×His-GST-EGFP-6×His and pCAMBIA3201 plasmid DNA using chip elution and soaking method elution were significantly different, P<0.05, and the plasmid DNA recovery rates of the chip elution solution of the two plasmid DNAs were 2.002 times and 2.164 times that of the filter paper soaking solution, respectively; the recovery rate comparison results showed that whether it was a plasmid DNA with a molecular weight less than 10,000 bp or a plasmid DNA greater than 10,000 bp, the use of elution chip 11 in conjunction with an automatic microfluidic system for plasmid DNA elution could make the plasmid DNA stock solution almost the same, while the use of filter paper soaking method showed different degrees of recovery rate reduction, suggesting that the elution of plasmid DNA by soaking method was not thorough, and the comparison results showed the high efficiency of elution chip 11.

[0057] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A plasmid DNA filter paper elution assembly, characterized in that: include: An elution chip, comprising a chip body and a closing cover, wherein the chip body is provided with an elution cavity and three liquid inlet channels and three liquid outlet channels connected to the elution cavity, the upper surface of the chip body is provided with an opening, three liquid inlets and one liquid outlet, the opening is correspondingly connected to the elution cavity and is used to place filter paper containing plasmid DNA, the closing cover is used to seal the opening, the three liquid inlets are respectively connected to one end of the three liquid inlet channels away from the elution cavity, and the liquid outlet is connected to one end of the three liquid outlet channels away from the elution cavity; The chip carrier has a positioning groove on the top for placing the elution chip, and a through hole is provided at the bottom of the positioning groove, which passes through the chip carrier from top to bottom. After the elution chip is placed in the positioning groove, the elution chamber is located above the through hole; and The ultrasonic vibration mechanism comprises a water bag and an ultrasonic probe arranged in the water bag, wherein the water bag extends into the positioning groove through the through hole, and the water bag is used to fit the position of the chip body corresponding to the elution cavity.

2. The plasmid DNA filter paper elution assembly according to claim 1, characterized in that: The chip body includes a bottom sealing plate and a base plate which are bonded to each other. The elution chamber, the three liquid inlet channels and the three liquid outlet channels are all arranged between the bottom sealing plate and the base plate. The opening, the three liquid inlets and one liquid outlet are all arranged on the side of the base plate away from the bottom sealing plate.

3. The plasmid DNA filter paper elution assembly according to claim 1, characterized in that: The aperture of the through hole gradually decreases from an end away from the positioning groove to an end close to the positioning groove, and the water bag is in a truncated cone shape that matches the shape of the through hole.

4. The plasmid DNA filter paper elution assembly according to claim 1, characterized in that: The ultrasonic vibration mechanism also includes a water cooling unit. The interior of the water bag is filled with water. A water inlet joint and a water outlet joint are provided on the water bag. The water inlet joint and the water outlet joint are respectively connected to the water outlet and water inlet of the water cooling unit through water pipes. The water cooling unit cools the water in the water bag by means of water circulation.

5. The plasmid DNA filter paper elution assembly according to claim 1, characterized in that: The elution chamber has relatively oppositely arranged planar chamber walls and an arc-shaped chamber wall protruding away from the planar chamber wall. Three liquid inlet channels are connected to the planar chamber wall, and three liquid outlet channels are connected to the arc-shaped chamber wall. The direction in which one of the liquid inlet channels is connected to the elution chamber is perpendicular to the planar chamber wall, and the directions in which the other two liquid inlet channels are connected to the elution chamber are perpendicular to each other. The directions in which the three liquid inlet channels are connected to the elution chamber intersect at the center of the elution chamber.

6. The plasmid DNA filter paper elution assembly according to claim 1, characterized in that: The closing cover includes a cover body, a plunger and a silicone coating. The plunger is arranged on one side of the cover body, and the diameter of the plunger is smaller than the diameter of the cover body. The silicone coating is arranged on the side of the cover body facing the plunger and surrounds the plunger. The plunger is used to seal the opening, and the silicone coating is used to contact the periphery of the opening to perform a sealing effect.

7. An automatic microfluidic system, characterized in that: It comprises three eluent sample tubes, an eluent collection tube, a syringe pump, a touch-type industrial computer and a plasmid DNA filter paper elution component as described in any one of claims 1 to 6; The three liquid inlets correspond to the three eluent sample tubes one by one and are connected through liquid inlet capillaries, and the liquid outlet is connected to the eluent collecting tube through a liquid outlet capillary; the injection pump is used to pump sterile-filtered air into the three eluent sample tubes to increase the air pressure in the eluent sample tubes so as to pump the eluent in the eluent sample tubes into the elution cavity and then flow into the eluent collecting tube, and the touch-type industrial control computer is electrically connected to the injection pump and the ultrasonic probe.

8. The automatic microfluidic system according to claim 7, characterized in that: The eluent sample tube includes a tube body and a tube cover detachably arranged on the tube body, one end of the liquid inlet capillary away from the liquid inlet passes through the tube cover and extends to the bottom of the tube body, the output port of the injection pump is connected to one end of the gas supply capillary, and the other end of the gas supply capillary passes through the tube cover and extends to the top of the tube body. The injection pump pumps out sterile filtered air and transmits it to the eluent sample tube through the gas supply capillary, thereby increasing the air pressure in the eluent sample tube and pumping the eluent into the elution chip through the liquid inlet capillary. In the final stage of the elution procedure, the injection pump continuously pumps out sterile air and uses the air to displace the liquid in the liquid inlet channel, the elution chamber and the liquid outlet channel to the eluent collection tube.

9. The automatic microfluidic system according to claim 7, characterized in that: The automatic microfluidic system also includes a chassis, a sample tube support seat, a collection tube support seat and a capping mechanism. A mounting hole is provided on the top of the chassis, the chip support seat is arranged on the mounting hole, the ultrasonic vibration mechanism and the injection pump are both arranged in the chassis, the sample tube support seat is arranged on one side of the chassis, the three eluent sample tubes are installed on the sample tube support seat, the touch-type industrial computer is arranged on the other side of the chassis, the collection tube support seat is arranged on the top of the chassis, the eluent collection tube is installed on the collection tube support seat, the capping mechanism is arranged on the top of the chassis and is located above the chip support seat, and the capping mechanism is used to apply pressure to the closing cover of the elution chip placed on the chip support seat to fix the elution chip in the positioning groove.

10. An elution method, characterized in that: Using the automatic microfluidic system as described in any one of claims 7 to 9, the elution method comprises the following steps: S1. Load the elution chip into the positioning groove on the chip carrier, remove the closing cover, place the plasmid DNA filter paper horizontally into the elution chamber through the opening, seal the opening with the closing cover, install the eluent collection tube and the three eluent sample tubes with eluent in place, and connect the inlet capillary, the outlet capillary and the injection pump; S2. Set the running program through the touch-type industrial computer, click Start to start the running program, the syringe pump pumps sterile air into the three eluent sample tubes, pushes the set amount of eluent into the elution chip and fills the elution cavity; S3. Start the ultrasonic vibration mechanism, the ultrasonic probe emits an ultrasonic wave of a set power for 4 seconds, and then stops; S4. The syringe pump pumps sterile air into the three eluent sample tubes to push one third of the remaining eluent in the eluent sample tubes into the elution chamber; S5. Start the ultrasonic vibration mechanism, the ultrasonic probe emits an ultrasonic wave of a set power for 4 seconds, and then stops; S6. The syringe pump pumps sterile air into the three eluent sample tubes to push one-half of the remaining eluent in the eluent sample tubes into the elution chamber; S7. Start the ultrasonic vibration mechanism, the ultrasonic probe emits an ultrasonic wave of a set power for 4 seconds, and then stops; S8. The injection pump pumps sterile air into the three eluent sample tubes to push the remaining eluent in the eluent sample tubes into the elution chamber, and then the injection pump continues to run for 10 seconds until all the liquid in the inlet channel, the elution chamber and the outlet channel are pushed into the eluent collection tube, completing the plasmid DNA filter paper elution process.

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