WO1998001753A1

WO1998001753A1 - Blood separation module

Info

Publication number: WO1998001753A1
Application number: PCT/AU1997/000423
Authority: WO
Inventors: Charles Douglas Austwick; Howard Milne Chandler
Original assignee: Amrad Operations Pty. Limited
Priority date: 1996-07-05
Filing date: 1997-07-04
Publication date: 1998-01-15
Also published as: AUPO087196A0; ZA975981B

Abstract

A blood separation module for use with a test or assay device comprising a planar base member having at least one aperture extending therethrough, and a filter element located in or covering said aperture, the filter element being adapted to remove particulate material from a blood sample applied thereto.

Description

BLOOD SEPARATION MODULE

FIELD OF THE INVENTION

This invention relates to a unique and versatile blood separation module for use with medical, veterinary and other test or assay devices, and in particular relates to a separation module for separation of blood cells from whole blood samples to provide serum/plasma from the samples for use with a test or assay device.

BACKGROUND OF THE INVENTION

Prior International Patent Applications Nos. PCT/US92/04425 (WO 92/21977) and

PCT/US94/1 3982 (WO 95/16207) note that among the many analytical systems used for detection and/or determination of analytes, particularly analytes of biological interest, are chromatographic assay systems. Among the analytes of biological interest frequently assayed in serum or plasma using such systems are:

1 . hormones, such as human chorionic gonadotropin (hCG), frequently assayed as a marker of human pregnancy;

2. antigens, particularly antigens specific to bacterial, viral, protozoan and nematode pathogens, such as Streptococcus, hepatitis virus, and Giardia;

3. antibodies, particularly antibodies induced as a result of infection with pathogens, such as antibody to Helicobacter pylori, Mycobacterium tuberculosis, and to human immunodeficiency virus (HIV);

4. enzymes, such as aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, and glutamate dehydrogenase, frequently assayed as indicators of physiological function and tissue damage;

5. other proteins, polypeptides and peptides; 6. drugs, both therapeutic drugs, such as antibiotics, tranquillisers and anticonvulsants, and illegal drugs of abuse, such as cocaine, heroin, and marijuana; and

7. vitamins.

Chromatographic assay systems are widely used in the medical, veterinary, food and environmental fields. In particular, chromatographic systems are frequently used by pathologists, physicians, medical technicians and other health workers for rapid in-office, in-field, or point-of-patient-care diagnosis and therapeutic monitoring of a variety of conditions and disorders. They are also increasingly used by patients themselves for at- home monitoring of such conditions and disorders.

Among the most important of such chromatographic systems are the "thin layer" systems in which a solvent moves as a solvent front across a thin, flat absorbent medium. Among the most important of tests that can be performed with such thin layer systems are immunoassays, which depend on the specific interaction between an antigen or hapten and a corresponding antibody. The use of immunoassays as a means of testing for the presence and/or amount of clinically important molecules has been known for some time.

Chromatographic techniques used in conjunction with immunoassays include a procedure known as immunochromatography. In general, this technique uses a disclosing reagent or particle that has been linked to an antibody to the analyte to be assayed, forming a conjugate. This conjugate is then mixed with a specimen and, if the analyte to be assayed is present in the specimen, the disclosing reagent-linked antibodies bind to the analyte to be assayed, thereby giving an indication that the analyte to be assayed is present. The disclosing reagent or particle can be identifiable by colour, magnetic properties, radioactivity, specific reactivity with another molecule, or another physical or chemical property. The specific reactions that are employed vary with the nature of the analyte being assayed and the sample to be tested. Although useful, currently available chromatographic techniques using test strips have a number of drawbacks. Blood samples contain particulate matter including whole cells and cell debris that can clog the pores of the chromatographic medium, greatly hindering the immunochromatographic process. In addition, blood samples contain coloured components that may make it difficult to read the test. Even if the sample does not create interference, it is frequently difficult with existing chromatographic test devices to apply the sample to the chromatographic medium so that the solvent front moves uniformly through the chromatographic medium to ensure that the sample reaches the area where binding is to occur in a uniform, straight-line manner.

It is an object of the present invention to provide a unique and versatile blood separation module which is simple and economic to manufacture, and which may be used in association with known test or assay devices, such as the devices disclosed in International Patent Applications Nos. PCT/US92/04425 and PCT/US94/1 3982, to remove particulate matter from blood samples before the samples are applied to the test or assay devices.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a blood separation module for use with a test or assay device, the module comprising:

(a) a planar base member having at least one aperture extending therethrough, and

(b) a filter element located in or covering said aperture, said filter element being adapted to remove particulate material from a blood sample applied thereto.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

DETAILED DESCRIPTION OF THE INVENTION

The separation module of the present invention is designed for use as an optional, removable extra component with known chromatographic test or assay devices such as the devices disclosed in International Patent Applications Nos. PCT/US92/04425 and PCT/US94/13982, the disclosures of which are incorporated herein by reference. In particular, the module of the present invention enables the separation of serum from a whole blood sample "in situ" on a chromatographic test or assay device.

Diagnostic tests for many conditions require the use of blood or serum/plasma. For example, detection of hCC for pregnancy testing, or HIV antibodies as an indicator of HIV infection. In general, plasma or serum has been obtained from whole blood specimens by either centrifuging the red cells from the blood, leaving plasma or by allowing the blood to clot and removing the serum. The relatively clear serum or plasma is then used for analysis. The term "serum" will be used herein to mean either serum or plasma.

Most test or assay devices which utilise chromatographic assay systems require the appropriate sample to be applied at a particular position of the assay device so that the assay procedure can then move the sample through the chromatographic system. The separation module of the present invention is designed to be used with such a test or assay device, and in particular to be removably located at the position of the device at which the sample is to be applied, so as to separate serum from the sample in this position and to apply the separated serum directly to the test or assay device at this position.

As broadly described above, the module of the invention comprises a planar base member, which is preferably rectangular in shape, which may be made of any suitable material. The base member may be made of laminated cardboard that is sufficiently impervious to moisture to contain the liquids involved in the performance of the assay carried out by the device, however other cellulose-based materials, such as paperboard or solid bleached sulfite (SBS) can also be used. Preferably, the base member is made of a flexible material such as a thin, non-stretchable plastic film material that is impervious to moisture, such as vinyl, Mylar, Lexan, polyethylene, polypropylene, and the like. The use of a flexible material is preferred as it enables the module of the invention to be closely applied to, and to adopt the profile of, the test or assay device to ensure that serum separated by the module is effectively supplied to the test or assay device.

The aperture or apertures in the base member are preferably in the form of holes or ports punched or otherwise formed to extend through the base member. Where the base member is generally rectangular in shape, the or each aperture is conveniently located about midway between the ends thereof.

The filter element located in or covering the or each aperture may be a porous matrix of any suitable material. Selection of appropriate filter materials is known to one of ordinary skill in the art; various porous or microporous materials can be used, including cheesecloth, paper, cotton, cellulose, nylon, rayon glass fibre, sintered glass nitrocellulose, or cellulose acetate of appropriate porosities, as well as fleeces or non- woven or porous polyester or other synthetic materials. The porosity of the filter element matrix can be suitably chosen to filter out cellular or particulate matter in whole blood samples.

In order to separate serum from whole blood samples, the filter element preferably comprises a selective filter membrane, most preferably a multilayer separation membrane of the type described in US Patent No. 5,240,862 and available commercially from

Spectral Diagnostics,lnc, Toronto, Ontario, Canada as a Membrane Plasma Separator

(MPS). The disclosure of US Patent No. 5,240,862 is incorporated herein by reference. Most preferably, for the separation of whole blood samples the filter element combines both a porous matrix (for example, non-woven polyester) together with a layer of multilayer separation membrane as described above.

Conveniently, the separation module of this invention is also provided with adhesive on the surface of the base member intended to be in contact with the test or assay device. The adhesive may be provided in any convenient form, for example in a layer covering all or part only of the surface or in discrete spots, strips or the like. Suitable adhesive materials are well known to persons skilled in the art. Preferably, the adhesive material is of a type which will permit the separation module to be removed from the test or assay device once the sample has been applied thereto through the separation module. Preferably also, before use, the adhesive on the separation module is covered with a removable cover or backing strip of a suitable material. In one particular embodiment of this invention a single cover or backing strip may be provided with a plurality of separation modules located thereon and temporarily adhered thereto in side-by-side or similar relationship.

The separation module may also be provided with a further supporting membrane of a suitable material which is permeable to the separated serum to assist in retaining the filter element in position in the or each aperture of the base member.

It will be appreciated from the foregoing detailed description that the present invention provides a blood separation module which permits conventional test or assay devices which require the use of a serum or plasma sample to be adapted in a convenient, simple and efficient manner to use with a whole blood sample, thereby avoiding the need for separate centrifuging or other treatment of the whole blood sample. The module of this invention can be made so as to be removable, so that after use with a conventional test or assay device it can be readily removed and disposed of. In addition, it is preferably made with a flexible base member so that it can be applied at the appropriate sample application position of the test or assay device and adapt to closely fit the profile of the device, ensuring efficient application to the device of serum separated from a whole blood sample.

Various features of one preferred embodiment of this invention are illustrated in the accompanying drawings which are included by way of illustration, not limitation of this invention.

In the accompanying drawings:

Figure 1 is a side elevation of a separation module in accordance with this invention;

Figure 2 is an exploded perspective view of the module of Figure 1 ; and

Figure 3 is a plan view of an assembly of a plurality of modules in side-by- side position on a single length of backing strip.

The separation module (10) shown in Figures 1 and 2 comprises a generally rectangular, flexible planar base member (1 1 ) having an aperture or port (12) extending through the base member, conveniently located generally midway between the ends of the base member (1 1). A filter element is located to cover the aperture (12) and comprises a matrix layer (13) of an open weave material such as nonwoven polyester to assist in distribution and retention of a whole blood sample, and a multilayer separation membrane (14), preferably a MPS membrane (available from Spectral Diagnostics). The matrix layer (1 3) may serve as a pre-filter and retard or bind the red blood cells, as well as providing the functions of retaining and distributing the blood sample. By functioning as a pre-filter it may help prevent red blood cells from blocking the separation membrane and thus enable recovery of extra serum. Optionally, a further supporting membrane of a suitable permeable material is provided to support the filter element (shown as 1 5 in dotted outline in Figure 1).

A layer of adhesive as indicated as 16 is applied to the underside of the base member (1 1 ), and in use this adhesive is covered prior to use by a removable cover or backing strip (not shown in Figures 1 and 2).

Figure 3 shows a plurality of separation modules (10) in side-by-side position adhered to a single length of backing strip for convenience of manufacture and use. Individual modules (10) may be removed from the backing strip as required for use, and to assist in this, an area (17) on each base member (1 1 ) is left free of adhesive so as to provide a "tab" to assist in removing the module (10) from the backing strip.

In use of the device shown in Figures 1 and 2, as previously described the device is applied to a chromatographic test or assay device and located such that the aperture and filter element is located at the position of the device at which the sample is to be applied.

The module is held in this position by the adhesive on the underside of the base member, and since the base member is flexible, the module can be closely fitted to the profile of the device. A whole blood sample is then applied to the or each aperture in the separation module and particulate materials such as blood cells are separated from the applied sample by the filter element with the serum passing through the filter element onto the test or assay device. Following application of the sample using the separation module, the module is removed from the assay device and the assay procedure is then carried out in the known way. As previously described, typical assay procedures include chromatographic assay procedures, particularly immunochromatographic assays which may be of either the "sandwich" or "competitive" categories as described in the prior

International patent applications incorporated by reference herein.

It will be appreciated that whilst the present invention is described with particular reference to a preferred embodiment of the separation module described in detail herein, many variations and modifications may be made to this particular embodiment without departing from the spirit and scope of the present invention as broadly described herein.

Claims

CLAIMS:

1. A blood separation module for use with a test or assay device, the module comprising: a. a planar base member having at least one aperture extending therethrough, and b. a filter element located in or covering said aperture, said filter element being adapted to remove particulate material from a blood sample applied thereto.

2. A module according to claim 1 , wherein said planar base member comprises a flexible, plastic film material.

3. A module according to claim 1 or claim 2, wherein said planar base member is generally rectangular in shape, and the or each aperture is located midway between the ends thereof.

4. A module according to any of claims 1 to 3, wherein said filter element comprises a porous matrix.

5. A module according to claim 4, wherein the porosity of said matrix is such as to filter out cellular or other particulate matter in whole blood samples.

6. A module according to claim 5 wherein said porous matrix comprises a material selected from cheesecloth, paper, cotton, cellulose, nylon, rayon, glass fibre, sintered glass, nitrocellulose, cellulose acetate or polyester or other synthetic fleece or non-woven materials.

7. A module according to any of claims 4 to 6, wherein said filter element further comprises a selective filter membrane.

8. A module according to claim 7, wherein said selective filter membrane selectively separates plasma from cellular and other particulate matter in whole blood samples.

9. A module according to any of claims 1 to 8, further comprising adhesive material on a surface of said planar base member.

10. A module according to claim 9, further comprising a removable cover or backing strip which covers said adhesive material.

1 1 . A module assembly comprising a plurality of modules according to claim 10 positioned on a single removable cover or backing strip.

12. An assembly according to claim 1 1 wherein said modules are in side-by-side relationship on said cover or backing strip.