EP4048444A1

EP4048444A1 - Device for controlled layering of liquids

Info

Publication number: EP4048444A1
Application number: EP21755843.6A
Authority: EP
Inventors: Mateusz ADAMSKI; Jan ZAROW; Tomasz FUJAWA
Original assignee: Spark Tech Sp zoo
Current assignee: Spark Tech Sp zoo
Priority date: 2020-06-30
Filing date: 2021-06-24
Publication date: 2022-08-31
Also published as: WO2022005314A1; PL434517A1

Abstract

A device for controlled layering of liquids, in particular for layering liquids prior separation with density gradient centrifugation, the device comprising a loading chamber (11), a draining chamber (40) and a liquid flow regulating element from the loading chamber (11) to the draining chamber (40), characterised in that the liquid flow regulating element comprises a piston type mechanism (19) and at least one flow transfer channel (32) in the wall of the flow segment (31), wherein the piston type mechanism (19) comprising a flow segment (31) and the piston (20) axially movable with respect to the flow segment (31), the piston (20) is provided with a shaft (23) and a sealing lip (22) tightly adhering to the inner surface of the flow segment (31) wall. The invention also relates to a density gradient centrifugation assembly comprising a controlled layering device and the centrifuge container (61).

Description

Device for controlled layering of liquids

The invention relates to a device for the controlled layering of liquids, in particular for layering of biological liquids prior separation by a density gradient centrifugation.

In the state of the art are known various solutions for pouring liquids into containers.

For example, European patent application EP3349897 A1 discloses an insert for a tube for separating blood into fractions of a desired density range by density gradient centrifugation, which insert is equipped with a partition dividing the interior of the container into at least two chambers in a vertical arrangement-the upper chamber and the lower chamber. Additionally, the partition has an opening, against which the guide adjoins, on which liquids, especially biological fluid, flow into a lower chamber of the centrifugation container. This application also discloses a method utilizing this insert for separating fluids using a density gradient centrifugation. A significant limitation of the above invention is the necessity to ensure tightness between the upper and lower chambers. In this case, it is necessary to maintain a seal between each of the discs of the partition and the wall of the centrifuge container. Moreover, it is necessary to maintain tightness between the entire contact surface of the discs constituting the partition, which is particularly difficult to manufacture, since the discs must be movable with respect to each other to maintain the function of the invention.

In turn, patent US2014/087360 discloses an insert and a method for separating blood into blood cells populations using density gradient centrifugation in a centrifuge container.

The insert consists of a partition that matches the shape of the inside of the centrifuge container. The partition divides the centrifuge container into an upper and a lower compartment. Optionally, the partition is provided with a support element below or above the partition for positioning the insert in the centrifuge container. The insert is provided with at least two openings, one of which is located closer to the bottom of the centrifuge container. The patent also describes a method of isolating a cell populations from a sample by density gradient centrifugation.

Patent US5132232A discloses apparatus and methods for collecting liquid samples, particularly blood and urine, fortesting and for separating samples into fractions. The apparatus consists of a centrifuge tube and an insert. The insert is divided into an upper part that allows the insert to be attached to the centrifuge container and a lower part, which is an incomplete partition with an opening. The full part of the partition wedges to the inside of the centrifuge container, and the opening in the partition allows for fluid collection from under the partition.

Invention in the patent US5314074A discloses the method for separating liquids with density gradient centrifugation with the use of an insert. The insert is in the form of a disk fitted to the inside of the centrifuge container with a plurality of capillary holes and cylindrical indentations at the edges of the disk. When placed in the centrifuge container the insert divides the centrifuge container into upper and lower chambers, holes and indentations in the insert enable continuous bidirectional flow of fluids between the chambers.

In turn, patent US5648223A describes a tube and methods for concentrating breast cancer cells using density gradient centrifugation. The tube is adapted to density gradient centrifugation, additionally it is equipped with transverse constriction members narrowing its lumen. The constriction members divide the tube into chambers connected to each other by permanent openings.

The limitations of the above-mentioned inventions are: the necessity to layer liquids one on top of the other by a manual method requiring high precision, the inability to stop the flow of liquid between the chambers in the centrifuge containers, which makes it impossible to regulate the speed of a liquid flow between the chambers, including closing and opening of holes between chambers.

In the solutions known in the art used for the separation of liquids with density gradient centrifugation, there is no or very limited ability to regulate the liquid flow while layering liquids one on top of the other in the tube prior centrifugation. The ability to precisely set the flow is especially important in the initial phase of layering liquids, when an interphase is formed. Lack of sufficient control during layering of liquids causes interphase disturbance and thus reduces the effectiveness of the subsequent cell fractions separation during the density gradient centrifugation. In the solutions known in the technology with the possibility of closing the flow between the chambers, it is difficult to ensure tightness between the individual structural elements.

The present invention aims to eliminate the above-mentioned limitations. In particular, the purpose has been to: increase the possibility of regulating the flow rate of liquid, reduce both number and contact surface of the elements necessary to maintain the tightness of the system. The purpose has also been to increase the precision of initial liquid flow velocity regulation through the device. The aim of the invention is a device for controlled layering of liquids, in particular for layering liquids prior separation with density gradient centrifugation, the device comprising a loading chamber, and a draining chamber, and a liquid flow regulating element from the loading chamber to the draining chamber, characterised in that the fluid flow regulating element comprises a piston type mechanism and at least one flow transfer channel in a wall of the flow segment, the piston type mechanism comprises a flow segment and a piston axially movable with respect to the flow segment and the piston is provided with a shaft and a sealing lip tightly adhering to an inner surface of the flow segment wall. The contact of the sealing lip with the wall of the flow segment is the only surface required to ensure tightness of the device.

Preferably, the flow transfer channel of the device for controlled layering of liquids is in the form of a groove in the inner surface of the wall of the flow segment or channel in the wall of the flow segment, the inlet of the channel is located in the inner wall surface of the flow segment and the outlet in the bottom wall of the flow segment. Also preferably the inlet of the flow transfer channel is below the junction of the loading chamber and the flow segment. It is particularly preferred if the cross-sectional area of the flow transfer channel increases from the inlet to the outlet, especially in the range from approx. 1 mm².

Preferably, the draining chamber of the device for controlled layering of liquids is provided with an adapter cap for the container, in particular a container for density gradient centrifugation. It is particularly preferred if the adapter cap is provided with a thread, especially a thread that is aligned with cap thread of the container for density gradient centrifugation.

Preferably, the sealing lip of device for controlled layering of liquids has an axial cross- section similar to an overturned letter C.

Preferably, the sealing lip is provided with a sealing ring, in particular a rubber or silicone sealing ring placed in a groove on the sealing lip, ensuring tightness by itself by preventing uncontrolled flow of liquid from the loading chamber into the draining chamber. The use of a sealing ring prevents leaks that may occur when the flow segment and the sealing lip on the piston are made with less precision, e.g. in the process of plastic injection moulding.

Also preferably if the piston of the device for controlled layering of liquids has a vent in the form of a channel through its entire length.

Preferably, the device for controlled layering of liquids is further provided with a piston guide fixedly connected to the loading or draining chamber, the piston guide enables only axial movement of the piston in the lumen of the flow segment. It is particularly preferred if the connection of the piston guide to the inner wall of the loading chamber or the draining chamber is made of at least one structural rib. It is also particularly preferred if both the piston and the guide are equipped with threads aligned with each other in the form of the piston thread and the guide thread.

In another aspect, the invention also relates to a density gradient centrifugation assembly characterised in that it comprises a device for controlled layering of liquids according to the invention and a centrifuge container. Preferably, in this assembly, the difference between the sum of the aperture radius of the flow segment and the depth of the flow transfer channel compared to the aperture radius of the centrifuge container is not more than 0.5 mm.

The advantages of the solution according to the invention include: the possibility of precise regulation of the flow rate of liquid through the system, reduction of the contact area for elements requiring tightness and reduction in their number, this reduces the production costs of the device, extends its durability and increases repeatability of layering liquids. An advantage of the solution according to the invention is also the possibility to precisely determine the lumen of the opening, either as the groove in the inner surface of the wall of the flow segment or channel in the wall of the flow segment, and thus to control the initial velocity of the liquid flow through the device.

The insert according to the invention has been shown in the examples and in the drawing, in which:

Fig. 1 illustrates a cut-away axonometric view through a device for controlled layering of liquids in which the position of the sealing lip of the piston in the flow segment blocks the flow of liquid from the loading chamber to the draining chamber;

Fig. 2 illustrates a cross-cut axonometric view through a device for controlled layering of liquids in which the position of the sealing lip of the piston in the flow segment allows liquid to flow from the loading chamber to the draining chamber;

Fig. 3 illustrates a cross-cut axonometric view through a device for controlled layering of liquids without piston with a groove-shaped flow transfer channel in the wall of the flow segment;

Fig. 4 illustrates the piston of a device for controlled layering of liquids;

Fig. 5 illustrates a density gradient centrifugation set consisting of a device for controlled layering of liquids and a centrifuge container;

Fig. 6 illustrates a cross-sectional cut axonometric view through a device for controlled layering of liquids without piston with a flow transfer channel in the wall of the flow segment; Fig. 7 illustrates a sealing lip equipped with a sealing ring placed in the mounting groove in version A, and in version B a sealing lip without sealing ring in the mounting groove;

Fig. 8 illustrates an adapter cap equipped with a crushing rib in ring shape, which seals connection of adapter cap with a centrifugation container;

Fig. 9 illustrates the deformation of a crushing rib in ring shape when the adapter cap thread is screwed onto the thread of a centrifugation container.

The device for controlled layering of liquids in an exemplary embodiment includes a loading chamber 11 communicating with a draining chamber 40, which includes a cylinder shaped flow segment 31. The device is equipped with an element for regulating the flow of liquid from the loading chamber 11 to the draining chamber 40. In an exemplary embodiment, the liquid flow regulating element consists of a piston type mechanism 19 and a flow transfer channel 32 located in the wall of the flow segment 31. The piston type mechanism 19 includes a flow segment 31 and a movable piston 20 equipped with a shaft 23 and a sealing lip 22.

The sealing lip 22 tightly adheres to the inner wall surface of the flow segment 31 and prevents uncontrolled flow of liquid from the loading chamber 11 into the drain cha draining chamber 40. The flow transfer channel 32 in the embodiment shown in Fig. 1, 2, and 3 are in the form of a groove in the inner wall surface of the flow segment 31. It is be appreciated that the flow transfer channel 32 may have other form, for example channel 33, where channel inlet 34 is located in the inner surface of the wall of the flow segment 31 and channel outlet 35 is located in the bottom wall of the flow segment 31, as illustrated in Fig. 6. The inlet of the flow channel 32 is below the junction of the loading chamber 11 and the flow segment 31. The cross- sectional area of the flow transfer channel 32 is variable, at channel inlet 34 it is 1 mm², increases towards its outlet and terminates at the bottom edge. The draining chamber 40 is provided with an adapter cap 41 with threads 42, aligned with density gradient centrifuge container cap thread, what enables tight attachment. Outer wall of the flow transfer channel 32 is aligned with the inner wall of the centrifuge container 61. The shape of the cross-section of the channel is selected to maintain the stiffness of the piston 20.

The sealing lip 22 of the piston 20 in the exemplary embodiment has an axial cross-section of a shape similar to an overturned letter C, what reduces potential leaks between the sealing lip 22 and the inner surface of the flow segment 31. The sealing lip 22 is made of medical polypropylene. The piston 20 has an axial vent 25 in the form of a channel through its entire length. This channel allows outflow of air from the draining chamber 40.

In another version of the device according to the invention, the sealing lip 22 of the piston 20 may be provided with the sealing ring 26, this further reduces potential leaks between the sealing lip 22 and the inner surface of the flow segment 31. The sealing ring 26 should be made of a material with greater flexibility than the piston, e.g. rubber or silicone.

In another embodiment, the device is additionally equipped with the piston guide 12 fixedly connected by four structural ribs 14 to the loading chamber 11. The piston guide 12 enables more precise axial sliding movement of the piston 20 in the lumen of the flow segment 31. In this exemplary embodiment, the piston 20 and the guide 12 may be equipped with threads aligned with each other in the form of the piston thread 21 and the guide thread 13.

The threading increases the precision of liquid flow through the flow transfer channel 32.

The piston shaft 23 is equipped with a key 24 which facilitates the rotary movement of the piston 20. The piston shaft 23 has a cross-shaped end that fits into a socket 52 in the form of a cap 51 with a bore.

A density gradient centrifugation kit, shown in Fig. 5, comprises a device for controlled layering of liquids and a centrifuge container 61. The kit enables attachment of centrifuge container, in this case a test tube, to the device. The centrifugation kit comprises a container 61 with a thread 62 aligned to the thread 42 of the adapter cap 41 and a device for the controlled layering of liquids. In this assembly, the sum of the aperture radius of the flow segment 31 and the depth of the flow transfer channel 32 is equal to the aperture radius of the centrifuge container 61. The performed tests have shown that the best results, preventing formation of droplets in the flow transfer channel 32, are obtained when the sum of the aperture radius of the flow segment 31 compared to the aperture radius of the centrifuge container 61 is within ±0.25 mm.

In another embodiment, the adapter cap is provided with a crushing rib 44 in ring shape which is crushed when the container 61 is screwed onto the adapter cap 41 (Fig. 9), this causes its deformation and additional sealing of the connection between the container 61 and the adapter cap 41.

The adapter cap may be additionally equipped with a positioning element 43, for example of a triangular shape, which conforms to the shape of the place where the container is placed in the stand (not shown). The positioning element 43 enables the repetitive positioning of the flow transfer channel 32, which may be used especially in the case of automation of controlled layering of liquids based on visual process control systems.

In yet another embodiment, the thread 21 of the piston 20 is screwed onto the thread 13 of the guide 12. The piston 20 is screwed in all the way so that the lip of the piston 22 is above the upper edge of the inlet 34 of the flow transfer channel 32, blocking the flow of liquid from the loading chamber 11 to the draining chamber 40. The device is then screwed onto a 15ml falcon centrifugation container 61 by screwing the thread 42 of the cap 41 onto the thread 62 of the container 61. The device with the attached container 61 is placed in a stand. First density gradient separation liquid- Histopaque 1077 Sigma- Aldrich - in the volume of 4ml is poured into the loading chamber 11. Onto the end of the pistone shaft 23, a socket 52 is placed and by turning the cap 51 with the key 52, the thread 21 of the piston 20 is partially screwed out from the thread 13 of the guide 12. After shifting the sealing lip 22 of the piston 20 below the inlet 34 of the channel 33 in the flow segment 31, the flow of liquid through the flow transfer channel 32 from the loading chamber 11 to the draining chamber 40 is enabled. After emptying the loading chamber 11, the liquid flow was disabled by screwing the piston 20 so that the lip of the piston 22 was above the upper edge of the flow transfer channel 32. The socket 52 was then removed from the key and 4 ml of whole blood was poured into the loading chamber 11. Onto the end of the piston shaft 23, a socket 52 is placed and by turning the cap 51 with the key 52, the thread 21 of the piston 20 is partially screwed out from the thread 13 of the guide 12. After shifting the sealing lip 22 of the piston 20 below the inlet 34 of the channel 33 in the flow segment 31, the flow of liquid through the flow transfer channel 32 from the loading chamber 11 to the draining chamber 40 is enabled. The blood flows creating an interface on the density gradient separation liquid. The initial flow rate should on one hand prevent formation of droplets in the flow transfer channel 32 and on the other ensure continuous flow, for this embodiment the diameter of the flow transfer channel 32 should be about 3 mm². After pouring about 0.5 ml of blood aperture of flow transfer channel 32 was gradually increased from about 3 mm² to about 5.5 mm². After emptying the loading chamber 11, the container 61 detached from the insert, capped, and was then centrifuged in order to separate the blood into fractions, subsequently the desired blood fractions were isolated. When handling the container 61 before and after centrifugation, great care was taken to avoid shaking.

Claims

Patent claims

1. A device for controlled layering of liquids, in particular for layering liquids prior separation with density gradient centrifugation, the device comprising a loading chamber (11), a draining chamber (40) and a liquid flow regulating element from the loading chamber (11) to the draining chamber (40), characterised in that the liquid flow regulating element comprises a piston type mechanism (19) and at least one flow transfer channel (32) in the wall of the flow segment (31), wherein the piston type mechanism (19) comprising a flow segment (31) and the piston (20) axially movable with respect to the flow segment (31), the piston (20) is provided with a shaft (23) and a sealing lip (22) tightly adhering to the inner surface of the flow segment (31) wall.

2. The device according to claim 1, characterised in that the flow transfer channel (32) is in the form of a groove in the inner surface of the wall of the flow segment (31) or channel (33) in the wall of the flow segment (31), the inlet (34) of the channel (33) is located in the inner wall surface of the flow segment (31) and the outlet (35) of the channel (33) in the bottom wall of the flow segment (31).

3. The device according to claim 1 or 2, characterised in that the inlet (34) of the flow transfer channel (32) is below the junction of the loading chamber (11) and the flow segment (31).

4. The device according to claim 2 or 3, characterised in that the cross-sectional area of the flow transfer channel (32) increases from the inlet (34) to the outlet (35), in particular in the range of approx. 1 mm².

5. The device according to claim 1, characterised in that the draining chamber (40) is provided with an adapter cap (41) for a container, in particular a container for density gradient centrifugation.

6. The device according to claim 5, characterised in that the adapter cap (41) is provided with a thread (42), in particular a thread that fits into the thread (62) of the container (61).

7. The device according to claim 5, characterised in that the cap (41) additionally has a crushing rib (44).

8. The device according to claim 1, characterised in that the sealing lip (22) has an axial cross-section similar to an overturned letter C, ensuring self-tightness preventing uncontrolled flow of liquid from the feeding chamber (11) to the drainage chamber (40).

9. The device according to claim 1, characterised in that the sealing lip (22) is provided with a sealing ring (26), in particular a sealing ring (26) made of rubber or silicone, placed in the mounting groove (27) on the lip (22), ensuring a self-tightness preventing uncontrolled flow of liquid from the chamber (11) into the drainage chamber (40).

10. The device according to claim 1, characterised in that the piston (20) has a vent (25) in the form of a channel through its entire length.

11. The device according to claim 1, characterised in that it further includes a piston guide (12) fixedly connected to the loading chamber (11) or the draining chamber (40), wherein the piston guide (12) is configured to allow axial movement of the piston (20) in the lumen of the flow segment (31).

12. The device according to claim 11, characterised in that the connection of the guide (14) of the piston (12) to the inner wall of the feed chamber (11) or the drainage chamber (40) is made by at least one structural rib (14).

13. The device according to claim 11, characterised in that the piston (20) and the guide (12) are provided with fitted threads in the form of a piston thread (21) and the guide thread (13).

14. The assembly for a density gradient centrifugation characterised in that it comprises the device as defined in any one of the preceding claims 1 to 13 and the centrifuge container (61).

15. The assembly according to claim 14, characterised in that the difference between the sum of the aperture radius of the flow segment (31) and the depth of the flow transfer channel (32) compared to the aperture radius of the centrifuge container (61) is not more than 0.5 mm.