Container for centrifugal separation and its production method

In a container for centrifugal separation that includes a container main body including a retention part in which a sample is retained, and in which a component of the sample in the retention part is centrifugally separated by rotating the container main body about its center axis, as a rotation axis, material having thixotropic properties has been applied to an entire bottom surface of the retention part.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2015-016712, filed on Jan. 30, 2015. The above application is hereby expressly incorporated by reference, in its entirety, into the present application.

BACKGROUND

The present disclosure relates to a container for centrifugal separation used in rotation-type centrifugal separation and its production method.

Conventionally, centrifugal separation apparatuses, which centrifugally separate each component of a sample such as blood in a container, were known. As such centrifugal separation apparatuses, there are so-called revolution-type centrifugal separation apparatuses and so-called rotation-type centrifugal separation apparatuses.

FIG. 13is a schematic diagram illustrating the configuration of a revolution-type centrifugal separation apparatus and its operation. As illustrated inFIG. 13, a revolution-type centrifugal separation apparatus performs centrifugal separation by revolving blood collection tube P1, in which blood BL and separation agent SA are stored, or the like with a closure set thereon. Specifically, each component of blood BL in blood collection tube P1is centrifugally separated by rotating rotation shaft Q1on which blood collection tube P1has been set by motor M1. Accordingly, extraction of blood plasma component BP alone is possible.

Meanwhile,FIG. 14is a schematic diagram illustrating the configuration of a rotation-type centrifugal separation apparatus and its operation. As illustrated inFIG. 14, a rotation-type centrifugal separation apparatus uses container P2for centrifugal separation including an inclined inner wall that becomes higher from the center toward the outer circumference, and in which a retention part that retains a sample in the inside of the container is formed. Specifically, after blood BL is stored in the retention part in container P2for centrifugal separation, container P2for centrifugal separation itself is rotated by rotation of rotation shaft Q2by motor M2. Centrifugal force induced by such rotation of container P2for centrifugal separation separates each component of blood BL and separation agent SP that has been stored in advance in container P2for centrifugal separation in such a manner that deposits are formed, in order from a component having lowest specific gravity, from the inner circumference toward the outer circumference. Then, when the rotation of the container for centrifugal separation is stopped, generally, a component having low specific gravity (blood plasma component BP) closer to the inner circumference exfoliates from the deposits, and is retained at a bottom of the container for centrifugal separation.

In the revolution-type centrifugal separation apparatus, a distance of movement of blood cells is generally long. Therefore, a relatively long time is required to separate a blood plasma component and blood cells from each other. In contrast, in the rotation-type centrifugal separation apparatus, a distance of movement of blood cells is short. Therefore, it is possible to shorten the length of time for centrifugal separation. Further, the rotation-type centrifugal separation apparatus has a merit that reduction in the size of the apparatus is possible, compared with the revolution-type centrifugal separation apparatus.

SUMMARY

However, in rotation-type centrifugal separation, blood moves upward along an inclined inner wall of a container for centrifugal separation, as illustrated inFIG. 15I. Therefore, there is a problem that hemolysis may occur by pressure of blood against the inner wall because red blood cells are pressed onto the inner wall by centrifugal force. Further, there is a problem that hemolysis may occur in a similar principle also in the vicinity of a trap space, in which deposits are formed, as illustrated inFIG. 15II.

When hemolysis has occurred, the same component as a component to be measured, a component that binds to the component to be measured or a component that reacts to a test reagent comes out from blood cells. Therefore, there is a problem that it is impossible to measure the concentration of the component to be measured or the like at high accuracy. Especially, potassium, AST (Aspartate transaminase), LDH (Lactate Dehydrogenase), Fe and the like greatly influence a measurement value, because they have high concentration in red blood cells.

Meanwhile, Japanese Unexamined Patent Publication No. 2001-239183 (Patent Document 1) discloses setting a separation agent only in a center space of a container for centrifugal separation. However, Patent Document 1 does not specially consider a structure that can suppress hemolysis as described above. Further, Specification of U.S. Pat. No. 7,947,186 (Patent Document 2) discloses radially applying a separation agent onto a bottom surface of a container for centrifugal separation. However, when the separation agent has been radially applied in such a manner, a protuberance of separation agent is formed. Therefore, hemolysis occurs by collision of blood cells with the protuberance. Further, Specification of U.S. Pat. No. 4,846,974 (Patent Document 3) discloses setting separation agent in a mass-like shape almost at a center of a bottom surface of a container for centrifugal separation. However, a structure that can suppress hemolysis is not considered at all also in Patent Document 3.

In view of the foregoing circumstances, the present disclosure provides a container for centrifugal separation that can suppress hemolysis caused by rotation-type centrifugal separation and its production method.

A container for centrifugal separation of the present disclosure includes a container main body including a retention part in which a sample is retained, and a component of the sample in the retention part is centrifugally separated by rotating the container main body about its center axis, as a rotation axis. In the container for centrifugal separation, material having thixotropic properties has been applied to an entire bottom surface of the retention part.

Further, it is desirable that the container for centrifugal separation includes a lid unit to be set toward an opening of the retention part of the container main body, and that the material having thixotropic properties has been applied also to an inner surface of the lid unit facing the retention part.

Further, it is desirable that the material having thixotropic properties has specific gravity in the middle of specific gravities of two components that are centrifugally separated from each other.

Further, it is desirable that the thickness of a coating formed by application of the material having thixotropic properties is greater than or equal to 5 μm and less than or equal to 1000 μm.

Further, the bottom surface of the retention part may include a funnel-shaped inclined surface.

Further, it is desirable that the material having thixotropic properties is gel.

Further, it is desirable that a trap part in which a component having relatively high specific gravity is stored when centrifugal separation has been performed on the sample is provided at an opening edge part of the container main body.

Further, the material having thixotropic properties may be applied to an inner surface of the trap part.

A method for producing a container for centrifugal separation of the present disclosure is a method for producing the aforementioned container for centrifugal separation of the present disclosure, and the material having thixotropic properties is applied by spin coating.

According to the container for centrifugal separation of the present disclosure, the container includes a container main body including a retention part in which a sample is retained, and a component of the sample in the retention part is centrifugally separated by rotating the container main body about its center axis, as a rotation axis. In the container for centrifugal separation, material having thixotropic properties has been applied to an entire bottom surface of the retention part. Therefore, it is possible to lower pressure received by blood cells in blood, compared with a case in which blood is in direct contact with the bottom surface of the retention part. As a result, it is possible to effectively suppress hemolysis of blood.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of a container for centrifugal separation of the present disclosure will be described in detail with reference to drawings. Here, the scale or the like of each composition element in the drawings appropriately differs from the actual one to make it easily recognizable.

FIG. 1is a schematic diagram illustrating the structure of a container1for centrifugal separation according to the present embodiment. Specifically, Section I ofFIG. 1is a perspective view of a container main body2of the container1for centrifugal separation. Section II ofFIG. 1is a perspective view of a lid unit3of the container1for centrifugal separation. Further,FIG. 2is a schematic perspective view of X-X cross section of the container main body2illustrated inFIG. 1.FIG. 3is a schematic sectional view illustrating an internal structure of the container main body2at X-X cross section. In the container1for centrifugal separation of the present embodiment, material having thixotropic properties has been applied to an entire bottom surface of the retention part. However,FIG. 1throughFIG. 3illustrate a state before application of the material having thixotropic properties. Meanwhile,FIG. 4is a schematic sectional view illustrating a state after application of the material having thixotropic properties.

As illustrated inFIG. 1throughFIG. 3, the container1for centrifugal separation of the present embodiment includes the container main body2and the lid unit3. The container main body2includes an inclined inner wall part20, a bottom part21, a trap bottom surface part23, a trap side surface part26, a fitting part24, which is to be fitted with the lid unit3, and a support outer wall part25, which supports these parts. The lid unit3includes an opening part30, in which an opening31for injecting a sample is formed, and a trap upper surface part33, which forms a trap space10atogether with the trap bottom surface part23and the trap side surface part26when the lid unit3is fitted with the container main body2.

The container1for centrifugal separation has a structure that is symmetric with respect to an axis (center axis C of the container) that passes through a center of the bottom part21and is perpendicular to the bottom part21(in other words, a structure similar to a rotation body about center axis C, as a center). Further, the container1for centrifugal separation has a cylindrical shape when viewed from the outside. When centrifugal separation is performed, the lid unit3in a state of being fitted with the fitting part24of the container main body2is, for example, firmly fixed to the fitting part24, and the container1for centrifugal separation is rotated about center axis C, as a rotation axis.

As illustrated inFIG. 3, a retention space10, into which a sample is injected, is formed by fitting the container main body2and the lid unit3together. Specifically, this retention space10is a space surrounded by the inclined inner wall part20, the bottom part21, the trap bottom surface part23, the trap side surface part26, the trap upper surface part33and the opening part30. In this retention space10, especially the space10a, formed by the trap bottom surface part23, the trap side surface part26and the trap upper surface part33, is a trap space in which a component having high specific gravity is trapped when centrifugal separation has been performed on a sample by rotating the container. In other words, the inclined inner wall part20, the bottom part21, the trap bottom surface part23, the trap side surface part26, the trap upper surface part33and the opening part30correspond to the retention part of the present disclosure. Further, the trap bottom surface part23, the trap side surface part26and the trap upper surface part33correspond to the trap part of the present disclosure.

The inclined inner wall part20is a funnel-shaped inclined surface, and formed in such a manner that the diameter of a cross section of the opening of the retention space10is tapered from its opening edge. A lower part of the retention space10is formed by this inclined surface. Further, a depression portion22is formed on a part of the inclined inner wall part20. The depression portion22has a depression portion side surface22bformed in such a manner that the diameter of a cross section of the opening of the depression portion22is tapered from its opening edge. The depression portion side surface22bis connected to a depression portion bottom surface22a.

Here, it is desirable that a connection part between the inclined inner wall part20and the depression portion side surface22bhas curvature to prevent hemolysis of a sample. Further, it is desirable that a connection part between the depression portion bottom surface22aand the depression portion side surface22balso has curvature. The depression portion22will be described later in detail.

Further, the inclined inner wall part20has a projection portion27in such a manner that the position of the projection portion27and that of the depression portion22are symmetric with respect to center axis C. The projection portion27is provided to adjust the position of the center of gravity of the container1for centrifugal separation itself that might have been shifted by formation of the depression portion22on the inclined inner wall part20. In the present embodiment, only one depression portion22is formed on the inclined inner wall part20. However, as a result of forming this single depression portion22alone, there is a possibility that the position of the center of gravity of the container1for centrifugal separation of the present embodiment is shifted from a designed center axis of the container. If such a shift in the position of the center of gravity is large, that is not desirable, because rotation of the container1for centrifugal separation becomes unstable.

Therefore, in the present embodiment, a difference in the moment of inertia induced by a shift in the position of a part (the part of the depression portion) of the inclined inner wall part20away from center axis C is offset by providing the projection portion27. Consequently, a position at which the projection portion27has been formed and a position at which the depression portion22has been formed are symmetric with respect to center axis C, and mass at the position at which the projection portion27has been formed is large. Further, a structure for adjusting such balance of the container1for centrifugal separation is not limited to the projection-shaped structure. For example, a structure in which material having high density has been embedded in the inclined inner wall part20in such a manner that a position at which the material has been embedded and the position at which the depression portion22has been formed are symmetric with respect to center axis C is adoptable. Alternatively, a structure that adjusts balance may be provided on or in the support outer wall part25instead of the inclined inner wall part20. Here, if a shift in the position of the center of gravity is not large (if the noise and vibration of the apparatus is not a problem, or the like), it is not always necessary to form the projection portion27.

The bottom part21connected to a lower edge of the inclined inner wall part20includes a flat surface connected to the lower edge of an inclined surface of the inclined inner wall part20. A connection part between the lower edge of the inclined surface and the flat surface is formed in such a manner to have curvature.

Here, it is not necessary that the bottom part21is flat. The bottom part21may be a convex curved surface. The container1for centrifugal separation is rotated about center axis C as a center. Therefore, centrifugal separation of a sample in the vicinity of center axis C tends to be difficult. However, if the bottom part21is formed by a convex curved surface, it is possible to further improve the centrifugal separation performance of the container1for centrifugal separation. This is because when the bottom part21is formed by the convex curved surface, force in a direction away from center axis C (this force is a gravity component along the curved surface) acts on the sample in the vicinity of the bottom part21during injection of the sample, and as a result, the sample in the vicinity of the bottom part21does not remain in the vicinity of center axis C but easily moves away from center axis C during rotation of the container1for centrifugal separation, and centrifugal force more efficiently acts on the sample.

The trap bottom surface part23connected to an upper edge of the inclined inner wall part20includes a horizontal flat surface. Further, a connection part between the flat surface and the upper edge of the inclined surface of the inclined inner wall part20is formed in such a manner to have curvature. This flat surface forms a bottom surface of the trap space10a. The trap side surface part26includes a vertical surface, which is connected to the flat surface of the trap bottom surface part23in such a manner to be perpendicular to the flat surface. This vertical surface forms a side surface of the trap space10a.

The trap space10ahas a ring shape with center axis C as its center, and the volume of the trap space10ais designed based on the amount of sample to be injected.

The support outer wall part25extends downward from the trap side surface part26while surrounding the whole inclined inner wall part20, and a lower edge of the support outer wall part25is located lower than the bottom part21. Accordingly, the container main body2is stably supported by the support outer wall part25.

The opening part30of the lid unit3has, for example, a truncated conical shape. The opening part30has an inclined surface formed in such a manner that the diameter of a cross section of the opening is tapered toward the opening31. An upper part of the retention space10is formed by this inclined surface. In the present embodiment, the container1for centrifugal separation is rotated while the opening31is kept open. Alternatively, the opening31may be structured in such a manner to be openable and closable, if necessary. The trap upper surface part33connected to the lower edge of the opening part30includes a substantially horizontal flat surface that is connected to the lower edge of the inclined surface of the opening part30in such a manner to have curvature. This flat surface forms the upper surface of the trap space10a.

Further, as described above,FIG. 4illustrates a state in which a coating40has been formed by applying material having thixotropic properties to the entire bottom surface of the retention part of the container1for centrifugal separation, illustrated inFIG. 1throughFIG. 3. The retention part is formed by the inclined inner wall part20, the bottom part21, the trap bottom surface part23, the trap side surface part26, the trap upper surface part33and the opening part30, as described above, and the bottom surface of the retention part includes at least an inner surface of the bottom part21and an inner surface of the inclined inner wall part20. Further, the expression “applying material to the entire bottom surface” means that it is not always necessary that the material is applied exactly to 100% of the bottom surface, and that an effect of suppressing hemolysis at the same level as the case of applying the material to substantially 100% of the bottom surface should be obtainable. A generally allowable error, such as a production error, is about 5%. Therefore, the material should be applied, for example, to at least 90% of the inner surface of the inclined inner wall part20. Further, it is desirable that the material having thixotropic properties is evenly applied continuously without a break. It is desirable that the material is evenly applied continuously without a break especially for the rotation direction of the container1for centrifugal separation (the circumference direction of the retention part).

Further, it is desirable that material having thixotropic properties is applied not only to the bottom surface of the retention part but also to the inner surface of the trap bottom surface part23, the inner surface of the trap side surface part26, the inner surface of the trap upper surface part33and the inner surface of the opening part30, as illustrated inFIG. 4. Blood is in contact also with these inner surfaces during centrifugal separation. Therefore, if the material is applied also to these inner surfaces, it is possible to suppress also hemolysis that may occur by contact of blood with these inner surfaces.

As the aforementioned material having thixotropic properties, material in a gel state that is usable as so-called separation agent may be used. The separation agent is appropriately selected, based on a component having low specific gravity and a component having high specific gravity to be separated from each other in a sample, from materials having specific gravity in the middle of the specific gravity of the component having low specific gravity and the specific gravity of the component having high specific gravity. Specifically, when blood plasma (a component having low specific gravity) and blood cells (a component having high specific gravity) in blood are separated from each other, a material having specific gravity in the middle of the specific gravity of blood plasma and the specific gravity of blood cells should be selected.

The coating40having thixotropic properties functions as a separation agent, and also functions as a protection coating for suppressing hemolysis.

Specifically, as material having thixotropic properties, for example, S Collect (Registered Trademark)(manufactured by SEKISUI MEDICAL CO, LTD.) or PS-Gel (manufactured by NIPPOINPAINT Co., Ltd.) may be used. Alternatively, material that is generally used as a separation agent may be used besides these kinds of material. Composition for separation disclosed, for example, in Japanese Unexamined Patent Publication No. 2003-294731, Japanese Unexamined Patent Publication No. 2001-165928 or Japanese Unexamined Patent Publication No. 10(1998)-010122 may be used.

Further, it is desirable that the thickness of the coating40made of material having thixotropic properties is greater than or equal to 5 μm and less than or equal to 1000 μm. Since the size of red blood cells is 7 μm through 8 μm, it is desirable that the thickness is 5 μm or greater, which is at least half of the diameter of a red blood cell, to sufficiently achieve an effect of suppressing hemolysis. Further, 200 μm or greater is more desirable. Further, as described above, the coating40made of material having thixotropic properties flows into the trap space10awhen centrifugal separation has been performed, and functions also as a separation agent. However, if a large amount of material flows, the thickness of a layer of separation agent formed in the trap space10abecomes great. Therefore, a long time is needed to perform separation. Hence, it is desirable that the thickness of the coating40having thixotropic properties is less than or equal to 1000 μm. Here, the thickness of the coating40means an average thickness of the evenly formed coating40applied to the inner surface of the inclined inner wall20excluding the depression portion22. Further, the expression “an average thickness is X μm” means that the maximum value and the minimum value of the thickness of the coating are within the range of X±10%.

Further, the coating40may be formed by applying material having thixotropic properties by spin coating. The conditions for producing the coating, such as conditions of spin coating, will be described later in detail.

Further, the trap space10aafter formation of the coating40is filled with a separation agent41. In the present embodiment, the material of the separation agent41and the material of the coating40are the same material.

Further, centrifugal separation is performed, for example, by using a centrifugal separation apparatus50, as illustrated inFIG. 5. The centrifugal separation apparatus50includes a casing51that has an open-close lid51aand forms a storage space52for storing the container1for centrifugal separation, and a rotation table53that is provided in the storage space52, and on which the container1for centrifugal separation is mounted. The container1for centrifugal separation is stored in the storage space52in a state in which the open-close lid51ais open, and mounted on the rotation table53. The rotation table53is rotationably supported by a rotation mechanism (for example, a motor or the like), which is not illustrated. The rotation table53rotates the container1for centrifugal separation in a state in which center axis C of the container1for centrifugal separation mounted on the rotation table53and rotation axis R of the rotation table53coincide with each other.

Next, the depression portion22on the inclined inner wall part20will be described in detail.FIG. 6is a schematic sectional perspective view illustrating the state of the inside of the container for centrifugal separation during centrifugal separation.FIG. 6illustrates a state in which deposits, as a resultant of centrifugal separation, have been formed in a region closer to the outer circumference of the retention space10as a result of performing centrifugal separation on a sample including a component5ahaving low specific gravity and a component5bhaving high specific gravity. These deposits have a structure in which a layer of the component5ahaving low specific gravity, a separation layer4, and a layer of the component5bhaving high specific gravity are present in this order from the inner circumference side. Here, the separation layer4is a layer formed of the aforementioned separation agent41filled in the trap space10aand the material of the coating40that has flowed into the trap space10a.

Further, as illustrated inFIG. 6, the depression portion22is formed at a position in such a manner that the depression portion22crosses interface S between a sample that was moved away from a center during rotation (after centrifugal separation, especially the component5ahaving low specific gravity) and air. Accordingly, a part of the component5ahaving low specific gravity that is present on the depression portion22easily exfoliates from the deposits, compared with the other part of the component5apresent in the other area.

It is desirable that the shape of the depression portion22is a sector with center axis C, as a center (including a truncated sector, in which a part including the center of a sector has been cut off) to reduce an obstacle when a sample moves up on the inclined surface of the inclined inner wall part20and when the component having low specific gravity moves down on the inclined surface of the inclined inner wall part20.

Next, process of a centrifugal separation method using the container1for centrifugal separation and the centrifugal separation apparatus50, as described above, will be described.FIG. 7is a schematic sectional diagram illustrating steps of the centrifugal separation method.

First, the aforementioned container1for centrifugal separation in which material having thixotropic properties has been applied to the entire bottom surface of the retention part is prepared. Further, a sample5is injected to the retention space10from the opening31of the container1for centrifugal separation (Section I ofFIG. 7). The sample5is injected, for example, by using a pipette or a syringe.

Next, the container1for centrifugal separation in which the sample5has been injected is mounted onto the rotation table53of the centrifugal separation apparatus50and rotated. At this time, components of the sample5and the material having thixotropic properties are separated according to specific gravity by centrifugal force of rotation, and deposits are formed closer to the outer circumference of the retention space10(section II ofFIG. 7). A component5bhaving high specific gravity is trapped in the trap space10aby a trap part (the trap bottom surface part23, the trap side surface part26and the trap upper surface part33) and the separation agent4(material having thixotropic properties).

Next, when rotation of the container1for centrifugal separation stops, exfoliation of a part of the component5ahaving low specific gravity that is present on the depression portion22starts by presence of the depression portion22, as a trigger (section III ofFIG. 7). Further, exfoliation of the other part of the component5agradually progresses in such a manner to follow the exfoliation of the part of the component5aon the depression portion22. Meanwhile, the component5bhaving high specific gravity remains, as it is, in the trap space. Then, when all the component5ahaving low specific gravity exfoliates from the deposits, the component5ahaving low specific gravity accumulates in a lower part of the retention space10, and a state in which the component5ahaving low specific gravity alone has been extracted and become collectable is induced (section IV ofFIG. 7).

Next, specific examples of the container for centrifugal separation of the present disclosure and its effects will be described.

FIG. 8Iis a sectional diagram illustrating a container for centrifugal separation of the present example.FIG. 8IIis a perspective view illustrating the container for centrifugal separation of the present example.FIGS. 8I and 8IIillustrate a state of the container for centrifugal separation before the aforementioned material having thixotropic properties is applied. The specific size of main structures of the container for centrifugal separation illustrated inFIGS. 8I and 8IIis as follows:

diameter φ2of a circumference including a projection portion for adjusting balance=14 mm;

height L1of a main body member=18.1 mm;

depth L2of a space formed by an inclined inner wall part=9 mm;

depth D of a depression portion=0.8 mm;

angle θ1 formed by an inclined surface of the inclined inner wall part and a center axis=48°;

angular range θ2 occupied by the depression portion in a circumferential direction=47°; and

distance R from a center of a bottom part to the depression portion along the inclined surface of the inclined inner wall part=4.1 mm.

Here, 0.5 g of S Collect (Registered Trademark)(manufactured by SEKISUI MEDICAL CO, LTD.) was dispensed in the retention part of the container main body2of the container for centrifugal separation illustrated inFIGS. 8I and 8IIby using a syringe. The container main body2was set in a centrifugal separation apparatus, and spin coating was performed by rotating the container main body2at 15000 min−1for 30 seconds (including 10 seconds for acceleration and 10 seconds for deceleration). As a result, a coating having the thickness of 200 μm was formed on the entire bottom surface of the retention part of the container main body2.

Further, material having thixotropic properties was applied also to the inner surface of the lid unit3of the container for centrifugal separation illustrated inFIG. 8I. Specifically, as illustrated inFIG. 9, the lid unit3was set on the rotation table60of the centrifugal separation apparatus with the opening31directed downward, and fixed by a press member61. Then, a space in the inner surface of the lid unit3was filled with material70having thixotropic properties, and spin coating was performed by rotating the lid unit3at 15000 min−1for 30 seconds (including 10 seconds for acceleration and 10 seconds for deceleration). As a result, a coating having the thickness of 200 μm was formed on the entire inner surface of the lid unit3.

After the coating was formed on the inner surface of the container main body2and the lid unit3as describe above, the container main body2and the lid unit3were fitted together and welded by ultrasonic waves.

In the present example, after the coating was formed on each of the container main body2and the lid unit3, the container main body2and the lid unit3were joined together to form the container1for centrifugal separation. However, it is not necessary that the container1for centrifugal separation is formed in such a manner. After the container main body2and the lid unit3are joined together, the coating may be formed in a similar manner to the above method by dispensing 0.5 g of S Collect (Registered Trademark) (manufactured by SEKISUI MEDICAL CO, LTD.) by using a syringe, and by performing spin coating by rotating the container for centrifugal separation by using the centrifugal separation apparatus.

Then, centrifugal separation was performed on whole blood of a man (male) of 45 years of age by using the container for centrifugal separation to which material having thixotropic properties had been applied as described above, and LDH (Lactate Dehydrogenase) in a separated blood plasma component was measured. The whole blood had been collected by using a heparin blood collection tube. Centrifugal separation was performed by rotating the whole blood at 18000 min−1for 2 minutes. Measurement of LDH was performed by using FDC7000 (manufactured by FUJIFILM Corporation).

Further, for the purpose of comparing the above case with a case in which centrifugal separation was performed by using a revolution-type centrifugal separation apparatus, centrifugal separation was performed on the whole blood by using ACNO3 (manufactured by Atom vet's medical), as the revolution-type centrifugal separation apparatus, and the concentration of LDH and the concentration of Hb (hemoglobin) in the blood plasma component were measured. Centrifugal separation was performed by rotating the whole blood at 8000 min−1for 10 minutes. LDH is a component contained in red blood cells, as described above, and the concentration of Hb (hemoglobin) is a diagnosis item and usable as an index indicating hemolysis. Therefore, these two concentrations were measured.

FIG. 10illustrates the concentration of LDH and the concentration of Hb (hemoglobin) in a blood plasma component that has been centrifugal separated. Here, IU/L, which is the unit of the concentration of LDH illustrated inFIG. 10, is convertible by 1 IU/L=1.67×10−6kat/L.

The leftmost graph inFIG. 10represents the concentration of LDH and the concentration of Hb (hemoglobin) in a blood plasma component that has been centrifugally separated by revolution-type centrifugal separation. The second graph from the left inFIG. 10represents the concentration of LDH and the concentration of Hb (hemoglobin) in a blood plasma component that has been centrifugally separated by rotation-type centrifugal separation without applying material having thixotropic properties to the container for centrifugal separation. Further, the third graph from the left inFIG. 10represents the concentration of LDH and the concentration of Hb (hemoglobin) in a blood plasma component that has been centrifugally separated by rotation-type centrifugal separation after applying material having thixotropic properties to the inner surface of the lid unit of the container for centrifugal separation. The rightmost graph inFIG. 10represents the concentration of LDH and the concentration of Hb (hemoglobin) in a blood plasma component that has been centrifugally separated by rotation-type centrifugal separation after applying material having thixotropic properties to the entire bottom surface of the retention part in the container for centrifugal separation.

The graphs inFIG. 10show that the measurement result of the concentration of LDH and the concentration of hemoglobin when the material having thixotropic properties was applied to the entire bottom surface of the retention part in the container for centrifugal separation is closest to the measurement result of the concentration of LDH and the concentration of hemoglobin obtained when the revolution-type centrifugal separation was performed. Specifically, it was found out that effective suppression of hemolysis was possible when material having thixotropic properties had been applied to the entire bottom surface of the retention part in the container for centrifugal separation. It was found out that when the material having thixotropic properties had not been applied, or when the material having thixotropic properties had been applied only to the inner surface of the lid unit, the concentration of Hb was relatively high by the influence of hemolysis, and that the concentration of LDH was a value closest to an upper limit in a normal range. When the material having thixotropic properties had been applied to the lid unit, some improvement was observed. Therefore, a more excellent effect is achievable when the material is applied to both of the entire bottom surface of the retention part and the inner surface of the lid unit.

Next, an example representing a relationship between the thickness of the coating40made of material having thixotropic properties and an effect of suppressing hemolysis will be described. Here, the concentration of LDH was measured for each of a case in which the coating40with the thickness of 200 μm was formed, a case in which the coating40with the thickness of 20 μm was formed, and a case in which the coating40with the thickness of 5 μm was formed. The coating40for each thickness was formed by spin coating. Specifically, 0.5 g of S Collect (Registered Trademark)(manufactured by SEKISUI MEDICAL CO, LTD.) was dispensed by using a syringe, and the container main body2was set in a centrifugal separation apparatus, and rotated at 15000 min−1for 30 seconds in a similar manner to the aforementioned example. As a result, the coating40of 200 μm was formed. The container main body2was rotated at the same rotation number for 120 seconds, and as a result, the coating40of 20 μm was formed. The container main body2was rotated at the same rotation number for 150 seconds, and as a result, the coating40of 5 μm was formed.

Regarding the thickness of the coating40, the thickness of the coating40formed on the inner surface of the inclined inner wall part20at a point indicated by arrow A, as illustrated inFIG. 11, was measured. As a measuring machine, a multi-layer coating thickness measuring machine SI-T10/SI-T10U manufactured by KEYENCE CORPORATION was used. Further, in the present example, the coating40was formed by spin coating. Therefore, the thickness of the coating40formed on the inner surface of the inclined inner wall part20is almost even, and the maximum value and the minimum value of thickness are within the range of ±10% of an average thickness.

FIG. 12uses, as a base (zero), the concentration of LDH when LDH in a blood plasma component was measured after performing centrifugal separation by using the container1for centrifugal separation in which the coating40of 200 μm was formed. With respect to this base,FIG. 12illustrates a difference in concentration when LDH was measured after forming the coating40of 20 μm and a difference in concentration when LDH was measured after forming the coating40of 5 μm was formed. As illustrated inFIG. 12, it has been found out that a difference in concentration of LDH increases and the effect of suppressing hemolysis becomes lower, as the thickness of the layer40becomes less. When the thickness of the coating40is 5 μm, a difference in concentration from the base is 3.5%. Therefore, it is desirable that this thickness is set as a lower limit.

In the above explanation, only the effect for the influence of hemolysis caused by destruction of red blood cells was described. However, it is conceivable that the container for centrifugal separation of the present disclosure has a protection function also for destruction of white blood cells and the like.