WO2007068811A1

WO2007068811A1 - Housing for assaying a biological sample by immunochromatography

Info

Publication number: WO2007068811A1
Application number: PCT/FR2006/002679
Authority: WO
Inventors: Benoît LAGARDE; Hamidou Samake
Original assignee: Diagnostica Stago
Priority date: 2005-12-14
Filing date: 2006-12-07
Publication date: 2007-06-21
Also published as: TW200730811A; FR2894674A1; AR058350A1

Abstract

Housing for assaying a biological sample by immunochromatography, comprising a base (10) and a cover (12) attached to one another and containing an assembly made up of a support band, a migration strip, filters, a reservoir of conjugates and an absorbent pad, which is carried and positioned by raised parts (40, 42, 48, 50) of the base (10) of the housing and which is held by protruding spikes (66, 68, 70) on the inner face of the cover (12).

Description

Assay box of a biological sample by immunochromatography

The invention relates to a dosing box of a biological sample by immunochromatography, this housing being usable for the determination of blood plasma, whole blood or any other biological sample.

It is known, for example from the French patent application 0501145 of the applicant, a method and an assay device in which a biological sample is deposited at one end of a housing containing a strip of porous material and migrates by capillarity to the another end of the strip, passing successively through a filter, a reservoir of conjugates, a result reading area comprising at least one capture reagent, and finally arriving at a buffer of absorbent material.

In known manner, the dosing box containing the migration strip is formed of a base and a suitable plastic cover which are fixed on one another, for example by clipping, latching or crimping. The migration strip is fixed by gluing on a thin strip of rigid plastics material, for example polyester, forming an assembly and handling support, with other elements comprising, at the first end of the strip, at least one filter and a reservoir of conjugates (this reservoir being formed of a small band or a plate of porous material, for example glass fibers), and at the second end of the strip, a buffer of absorbent material. The assembly formed by the support strip, the strip and the other elements glued on the support strip is enclosed in the housing, whose cover comprises a sample depositing well on the first end of the strip and a reading window of results, formed at an intermediate zone of the strip away from the filter and the conjugate reservoir on the one hand and the absorbent pad on the other hand. For assays to be performed reliably and reproducibly, these boxes must meet a number of conditions, such as:

the housing must ensure easy reading of the results of the immunological reaction,

- it must be convenient to handle,

- it must ensure the safety of the operator,

- it must be adaptable to a device for automatic reading of the results, - its closure must be hermetic to avoid sample leakage to the outside, while allowing an optimal migration of the sample in the strip,

a possible excess of liquid deposited in the well of the cover must be able to be collected inside the housing, without disturbing the dosing reaction,

the migration strip, which is the support for the immunological reaction, must be kept in the housing precisely so that the sample to be assayed can flow completely by migration in the strip to the absorbent pad after having crossed the conjugate reservoir and the zones containing the capture reagents, without accumulating in intermediate spaces,

- For the determination of a whole blood sample, the housing must contribute to the separation of blood cells and plasma.

The present invention particularly relates to a dosing housing optimally meeting all of these criteria.

It therefore proposes a dosing box of a biological sample by immunochromatography, comprising a base and a plastic cover fixed to one another and containing a set formed of a support band made of rigid plastic material, a wicking test strip, at least one filter and a reservoir of conjugates at a first end of the strip and a tampon absorbent located at a second end of the strip, the cap having a sample depositing well on the filter at the first end of the strip and a result reading window opening on an intermediate zone of the strip, characterized in that the base comprises raised support means and longitudinal and transverse positioning of the end portions of the support strip and in that the cover comprises support means on the filter, on the conjugate reservoir and on the absorbent pad for ensure optimal migration through the filter, the conjugate reservoir and the strip, of the sample deposited in the hood well.

The elevation, relative to the bottom of the housing, means for supporting and positioning the ends of the strip of plastic material carrying the migration strip and the other elements makes it possible firstly to position the strip in the housing while away from the bottom of the housing, which avoids the risk of flow of the sample outside the strip.

In addition, the support means provided on the cover ensure optimum contact with adequate clamping between the filter, the conjugate reservoir and the strip at the first end thereof, and between the absorbent pad and the strip at the second end thereof, so that the sample deposited in the hood well migrates by capillarity through the filter, the conjugate reservoir and the strip to the absorbent pad. This ensures the quality and accuracy of the dosing performed.

According to another characteristic of the invention, a chamber is formed around the raised means of support and positioning of the first end portion of the plastic strip under the deposition well, this chamber being intended to collect and confine a possible excess of liquid deposited in the well.

This prevents excess liquid, which is collected in the chamber formed in the bottom of the housing, disrupting the metering reaction. Advantageously, this chamber is separated from the rest of the housing by the elevated positioning means of the first end portion of the support strip.

Similarly, a liquid collection chamber is formed around the absorbent pad and raised means for supporting and positioning the second end portion of the plastic web.

In one embodiment of the invention, the positioning means of the plastic support strip are longitudinal and transverse ribs formed projecting on the base of the housing.

The longitudinal positioning ribs are for example L-shaped and are connected to longitudinal walls of the base of the housing. They thus constitute delimiting means of the aforementioned chambers formed around the raised means for supporting the end portions of the plastic strip.

The support means formed on the hood comprise:

an annular surface which is formed at the end of the deposition well and which is applied to the filter at the first end of the strip,

- Filter holding pins and the conjugate reservoir on the first end of the migration strip, and other absorbent pad holding pins on the second end of the strip and on the plastic support strip.

The annular surface formed at the end of the deposition well is parallel to the support strip and to the bottom wall of the housing in the case of a blood plasma dosing housing.

It is inclined obliquely with respect to the support strip in the case of a whole blood dosing box and is then supported on a separation filter blood cells and plasma.

This annular support surface and the filter are inclined upwards in the direction of the migration strip and the absorbent pad, the angle of inclination being approximately 5 ° to the horizontal in a preferred embodiment, and being more generally between 3 and 10 ° approximately.

To avoid clogging of the separation filter by the blood cells, grooves, preferably longitudinal, may be formed in this annular bearing surface.

The blood cell separation filter is itself placed on a filter for retaining impurities and delimits therewith a space for accumulation of blood cells separated from the plasma.

According to yet another characteristic of the invention, the housing comprises, on one of its walls, a notch for snapping or hooking on a corresponding element of a result reading apparatus.

This ensures a correct positioning and maintenance of the housing in the result reading apparatus, avoiding handling errors at this stage of the dosing operations.

The invention will be better understood and other characteristics, details and advantages thereof will appear more clearly on reading the description which follows, given by way of example with reference to the accompanying drawings, in which: FIG. a schematic perspective view of the base of a dosing unit according to the invention;

- Figure 2 is a schematic view of the inner face of the cover of this housing;

- Figure 3 is a schematic longitudinal sectional view of the hood;

- Figure 4 shows schematically the relative arrangement of the migration strip and other elements on a rigid plastic support strip;

- Figure 5 is a half-view in axial section and in perspective of the metering housing according to the invention;

FIG. 6 is an enlarged view of part of FIG. In the following description, by convention, the left-hand side or the left-hand end of an element shown in the accompanying drawings, will be referred to as the first part or end and the one to the right will be called the second part or second end. The dosing box shown diagrammatically in FIGS. 1 to 3 comprises a base 10 and a cover 12 which are generally rectangular in shape and which are fixed to one another by snapping or crimping by means of cylindrical fingers 14 formed on the face internal of the cover 12 and received in cylindrical housings 16 of the inner face of the base 10 of the housing. The asymmetric arrangement of the fingers 14 and the housings 16 with respect to a median transverse plane constitutes a keying means, avoiding fixing the cover 12 on the base 10 in the wrong direction.

This housing is intended to contain an assembly 18 shown schematically in FIG. 4 and comprising a rigid plastic support strip 20, such as, for example, polyester, on which a strip 22 is placed and fixed by means of a suitable adhesive. in porous material for the migration of a liquid sample, this strip 22 being for example based on nitrocellulose. On a first end of the strip 22 are deposited and fixed successively, by gluing, a reservoir 24 of conjugate product and a filter 26 impurity retention contained optionally in the sample to be assayed.

When this sample is composed of whole blood, an additional filter 28 for separating the blood cells and the plasma is placed and fixed at its ends by gluing on the support strip 18 and under the filter 26 for retaining impurities.

When the sample to be assayed consists of blood plasma, the filter 28 is not necessary and only the filter 26 for retaining impurities is fixed at its ends, by gluing, on the support strip 18 and on the conjugate reservoir 24. . This reservoir is itself formed of a small band or a wafer of porous material, for example based on glass fibers, and contains the conjugate products that will be used for the sample dosing reaction. A buffer 30 of absorbent material, for example based on cellulose, is placed and fixed on the second end of the migration strip 22.

In FIG. 4, the thicknesses of the support strip 20, the migration strip 22 and the other elements of the assembly 18 have been exaggerated for the sake of clarity. In a particular embodiment, the support strip 20 has a length of about 70 mm, a width of 5 mm and a thickness of about 0.3 mm. The migration strip 22 has a length of about 40mm, a width of 5mm and a thickness of about 0.25mm. The conjugate reservoir 24 has a length of about 7mm, a width of 5mm and a thickness of about 0.4mm. The impurity retaining filter 26 has a length of approximately 20 mm, a width of 5 mm and a thickness of approximately 0.35 mm when it is made of cellulose or 0.9 mm when it is made of glass fibers. . The blood cell and plasma separation filter 28 has a length of about 15 mm, a width of 5 mm and a thickness of about 0.6 mm.

The assembly 18 is positioned in the base 10 of the housing and supported by means specially designed for this purpose, which will now be described.

The bottom wall 32 of the base 10 of the housing has an elongated cavity 34 for receiving the assembly 18, and whose dimensions in length and width are greater than those of the assembly 18. Blocks are formed protruding from the bottom of this cavity to support the ends of the strip 20 of rigid plastic material of the assembly 18 and are associated with longitudinal and transverse wedging means of this band. More specifically, the longitudinal ends of the bottom of the cavity 34, corresponding to the first end portion 36 and the second end portion 38 of the strip 20 of the assembly 18, comprise projecting blocks 40 and 42 respectively. , in the form of a rectangular parallelepiped, whose width corresponds to the width of the strip 20 of the assembly 18 and whose lengths are approximately equal to twice their width. Two parallel tabs 44 extend the longitudinal edges of the first block 40 in the direction of the second block 42 and likewise, two longitudinal tabs 46 extend in the extension of the longitudinal edges of the second block 42 in the direction of the first block 40, these tabs 40 and 46 being intended to support for a certain length the longitudinal edges of the strip 20 of rigid plastic material of the assembly 18.

A rib 48 formed at the end of the first block 40 and a rib 50 formed at the end of the second block 42 form positioning stops of the longitudinal ends of the strip 20 of plastic when it is placed on the blocks 40 and 42. Side ribs 52 are formed protruding on the bottom of the cavity 34 on either side of the first block 40 to frame the first end portion 36 of the band 20, and side ribs 54 are also formed protruding on the bottom of the cavity 34 on either side of the tabs 46 of the second block 42 to transversely frame the second end portion 38 of the support strip 20. These lateral ribs 52 and 54 are L-shaped and are connected to the longitudinal walls of the cavity 34. Thus, the lateral ribs 52 define in the cavity 34 a first chamber 56 around the first block 40 and the lateral ribs 54 delimit in the cavity 34 a chamber 58 around the second block 42.

When the assembly 18 is placed in the cavity 34, the ends 36, 38 of the support strip 20 rest on the blocks 40 and 42 between the ribs 48, 50, 52 and 54 and the strip 20 is immobilized in translation parallel to the bottom of the cavity 34. It is then sufficient to fix the cover 12 on the base 10 of the housing to completely immobilize the assembly 18 by further exerting a predetermined tightening of certain parts of this assembly by means provided on the inner face of the cover 12. In general, this cover comprises a sample depositing well 60 and a result reading window 62, the well 60 being above the first block 40 of the cavity 34 when the cover 12 is fixed on the base 10 of the housing, and the window 62 of reading results opening between the ends of the longitudinal tabs 44 of the first block 40 and the longitudinal tabs 46 of the second block 42.

The well 60 is approximately in the form of a spherical cap, an ellipsoid cap, or a truncated cone, its major axis extending in the longitudinal axis of the cap and its minor axis being transverse. Its end 63 opening inside the housing is bordered by a flat annular surface 64 intended to be applied on the upper face of the filter 28 or the filter 26 of the assembly 18 of FIG. 4.

Cylindrical pins 66, 68 and 70 are projecting on the inner face of the cover 12 to extend towards the bottom of the cavity 34 when the cover is fixed on the base of the housing and to adequately tighten certain elements. of assembly 18 on the migration strip 22.

Two pins 66 are formed on the inner face of the pin 12 between the well 60 and the read window 62 and are intended to bear on the end of the filter 28 or the filter 26 which covers the first end of the migration strip 22 These cylindrical pins 66 are transversely aligned and located on either side of the longitudinal axis of the housing, their distance being less than the width of the filters 28 and 26.

A third pin 68 is formed protruding on the inner face of the cover 12, and is intended to bear on the first end 30a of the absorbent pad 30. This pin 68 is located on the longitudinal axis of the housing. Two other transversely aligned pins 70 are formed projecting on the inner face of the cover 12 on either side of its longitudinal axis and are intended to bear against the other end 30b of the absorbent pad 30 to apply it to the corresponding end 38 of the support strip 20. These two pins 70 have a length slightly greater than that of the pin 68 which supports the first end 30a of the absorbent pad 30 on the corresponding end of the migration membrane 22, to ensure the same clamping the pad 30 at its ends. The points of support of the pins 66, 68 and 70 on the elements of the assembly 18 have been represented by arrows in FIG.

Figures 5 and 6, which show a half-view in longitudinal section and in perspective of the assembled housing, to better visualize these elements. The casing of FIGS. 5 and 6 is intended for the determination of a whole blood sample and the assembly 18 contained in this casing comprises, under the sample deposit well 60, a first filter 26 for retaining any impurities contained in the sample to be assayed, placed on a filter 28 for separating the blood cells and the plasma, the filter 26 for retaining impurities being more rigid than the separation filter 28 and extending obliquely above it, in delimiting between them a space 72 in which the blood cells can accumulate, so as to avoid clogging and saturation filters.

The angle of inclination of the middle portion of the filter 26 with respect to the horizontal is less than 10 ° (it is about 5 ° in a particular embodiment) and the annular surface 64 of the lower end of the filter well 60 is inclined correspondingly, so as to be applied to the filter 26 over its entire periphery, without crushing the filter.

To prevent clogging by the separated blood cells of the whole blood sample deposited in the well 60, two grooves longitudinal lines 74 visible in FIG. 6 can be formed in the annular surface 64.

When a plasma sample for the assay is used, the filter 28 is not needed and the annular surface 64 of the lower end of the deposition well 60 is flat and horizontal and is applied to the impurity retaining filter 26 .

The housing which has just been described is used in the following way, for the determination of a whole blood sample for example:

The assembly 18 formed by the support strip 20, the migration strip 22 and the other elements shown in FIG. 4 being placed in the cavity 34 of the base 10 of the housing and the hood 12 being fixed on the base 10, it is possible to deposit a predetermined volume of the sample to be assayed in the well 60 of the cover 12 of the housing.

When this sample is whole blood, the blood cells (red blood cells, white blood cells and platelets) are separated from the plasma and retained by the filter 28. The plasma passes through this filter by migrating by capillarity and also passes through the reservoir 24 of conjugates to gain the migration strip 22. The proper holding and tightening of the filters by the base of the deposition well 60 and by the pin 66 guarantee a good migration of the plasma without risk of accumulation thereof in interstices formed between the support strip 20, the conjugate reservoir 24 and the filters. The plasma migrates into the strip 22 towards the absorbent pad 30 located at the other end of the assembly 18 and passes into the areas of the strip 22 where capture reagents have been deposited, these zones being visible in the window of FIG. reading 62. The plasma is absorbed by the buffer 30 at the other end of the assembly 18.

Any excess liquid deposited in the well 60 remains confined in the chamber 56 formed around the well 60, and any excess liquid absorbed by the buffer 30 will be confined in the chamber 58 at the other end of the housing, so that these excess liquid are kept at the portion of the strip where the assay reaction takes place and can not disturb this reaction.

The set of characteristics of the housing described above ensures an optimal migration of the plasma in the strip 22 and in the other elements of the assembly 18 and guarantees the quality of the assay performed.

Furthermore, this housing is intended to be used with an automatic meter reading results apparatus, which comprises optical detection means associated with longitudinal scanning means of the portion of the strip 22 appearing in the read window 62. This scanning can be performed optically or by translational displacement of the housing in the reading device, this housing then being positioned and held on a mobile carriage of the reading apparatus. A catching or latching notch is advantageously formed in a longitudinal wall of the base 10 of the housing, as shown in dashed lines at 76 in FIG. 1, for positioning and hooking up the housing in the reading apparatus or on the moving carriage of the reading device.

Claims

An immunochromatographic biological sample assay housing, comprising a base (10) and a cover (12) of plastic material, fixed to one another and containing a band assembly (18) ( 20) rigid plastic support a strip (22) of migration of the sample by capillarity and at least one filter (26) and a reservoir (24) of conjugates disposed on a first end of the strip and an absorbent pad (30) disposed on a second end of the strip, the cap (12) having a sample depositing well (60) on the filter (26) at the first end of the strip and a a result reading window (62) opening onto an intermediate region of the strip, characterized in that the base (12) of the housing comprises raised means (40, 42, 44, 46, 52, 54) for support and positioning longitudinal and transverse ends of the support strip (20) and in that the apot (12) comprises support means (64, 66, 68, 70) on the filter, on the reservoir (24) of conjugates and on the absorbent pad (30) to ensure optimum migration through the filter (26). ), the reservoir (24) of conjugates and the strip (22), the sample deposited in the well (60) of the hood.

2. Housing according to claim 1, characterized in that a chamber (56) is formed around the raised means (40) for supporting and positioning the first end of the support strip (20) under the deposition well (60). ), this chamber being intended to collect and confine any excess liquid deposited in the well.

3. Housing according to claim 2, characterized in that said chamber (56) is separated from the rest of the housing by raised means (52) for positioning the first end of the support strip (20).

Housing according to one of the preceding claims, characterized in that the means for positioning the support strip (20) are longitudinal and transverse ribs (48, 50, 52, 54) projecting from the housing base (12).

5. Housing according to claim 4, characterized in that the longitudinal ribs (52, 54) of positioning are L-shaped and are connected to longitudinal walls of the base (10) of the housing.

6. Housing according to one of the preceding claims, characterized in that a chamber (58) is formed around the raised means for supporting and positioning the second end of the support strip (20) to collect and confine a possible excess liquid flowing from the absorbent pad (30).

7. Housing according to one of claims 1 to 6, characterized in that the support means formed on the cover (12) comprise an annular surface (64) formed at the end of the deposition well (60) and applied on the above filter.

8. Housing according to claim 7, characterized in that said annular surface (64) is parallel to the support strip (20) and to the bottom of the base (10) of the housing in the case of a blood plasma dosing box .

9. Housing according to claim 7, characterized in that said annular surface (64) is inclined obliquely relative to the support strip (20) and the bottom of the base (10) of the housing in the case of a housing of dosing whole blood and is supported on a filter (26) for impurity retention placed on a filter (28) for separating blood cells and plasma.

10. Housing according to claim 2, characterized in that said annular bearing surface (64) and the filter (26) for impurity retention are inclined upwards towards the second end of the migration strip and the absorbent pad.

11. Housing according to claim 10, characterized in that the angle of inclination relative to the horizontal of said annular surface (64) and the filter (28) is about 5 °.

12. Housing according to one of claims 9 to 11, characterized in that said annular bearing surface (64) has grooves (74) for preventing clogging of the filter (28) by the blood cells.

13. Housing according to one of claims 1 to 12, characterized in that the filter (28) for separating blood cells is located under a filter (26) for retaining impurities and defines therewith a space ( 72) of accumulation of blood cells.

14. Housing according to one of the preceding claims, characterized in that the support means formed on the cover (12) comprise pins (66) for holding the filter or filters and the tank (24) of conjugates on the strip of migration, and pins (68, 70) for holding the absorbent pad (30) on the strip (22) and on the support strip (20) respectively.

15. Housing according to claim 14, characterized in that the cover (12) comprises two pins (66) for holding the filter or filters and the conjugate reservoir (24) on the migration strip, these two pins being located between the deposition well (60) and the result reading window (62).

16. Housing according to claim 14 or 15, characterized in that the cover (12) comprises at least one pin (68) for holding the first end (30a) of the absorbent pad on the migration strip and at least one pin ( 70) for maintaining the second end (30b) of the absorbent pad on the support strip (20), these pins having different heights to ensure the same tightening of the absorbent pad at its ends.

17. Housing according to one of the preceding claims, characterized in that it comprises a notch (76) latching in a result reading apparatus.