Directed-flow assay device

Abstract

A diagnostic assay device that directs an applied sample to the analytical membrane of a directed flow device. The device has a sample receiving port defined by layers of built-up material on one end of the test strip. The port contains the sample and specifically directs it to the membrane in a controlled fashion. Additional features include configuration of the housing in a general C-shape with the test strip spanning the opening of the C-shape to allow access by a reader device. A preferred method employs superparamagnetic particles to label the target analytes for detection and measurement by means of an electromagnetic reader device.

Description

BRIEF DESCRIPTION OF THE DRAWING

These and other aspects, features and advantages of the present invention will become more apparent upon consideration of the following description of preferred embodiments taken in conjunction with the accompanying drawing, in which like reference numerals designate like parts throughout:

FIG. 1 is an exploded perspective view of a directed flow assay device in accordance with the present invention;

FIG. 2 is a side sectional view of the assembled test strip of FIG. 1;

FIG. 3 is a perspective view of the bottom housing portion of the device of FIG. 1;

FIG. 4 is a perspective view of the inside of the top housing portion of the device of FIG. 1; and

FIG. 5 is a perspective view of the fully assembled device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description of preferred embodiments, reference is made to the accompanying drawings, which form a part hereof, and which show by way of illustration, specific embodiments of the invention. It is to be understood by those of working skill in this technological field that other embodiments may be utilized, and structural, as well as procedural changes may be made without departing from the scope of the present invention.

With reference now to FIGS. 1 to 5, directed flow assay device 10 in accordance with the present invention comprises immunoassay test strip 12, which has porous analytical membrane 14 mounted adjacent to and generally parallel with support member 11. Adhesive layer 13 (FIG. 2) anchors analytical membrane 14 to support member 11. The analytical membrane has a first end and a second end.

Superparamagnetic particles (not shown) may be present in the sample preparation outside the device. These particles are configured to bind with the target analytes in the sample. The membrane has a capture region intermediate to the first and second ends of the analytical membrane. The capture region generally has control and detection regions 28, shown in FIG. 1. The capture region is configured to capture labeled analytes moving from the first end of the analytical membrane toward the second end of the analytical membrane. Additional regions may be present, if desired, for example, for calibration. See, for example, calibration strips 25 (FIGS. 1 and 2) on protective membrane 24. This could equally be a dot, such as dot 27 in FIG. 5. As shown in FIG. 2, it could be either a line or a dot.

One aspect of the present invention is that it has sample receiving port 30 at one end of strip 12 for introduction of the sample to be analyzed. In prior devices, the sample receiving port is generally formed by the housing of the device, if at all. In the present invention, the sample receiving port is located generally on the strip, and is made or built up from layers of applied material.

The sample receiving port is formed by fluid sealing material 15 on the bottom, which is positioned over the support member. Preferably fluid sealing material 15 is hydrophilic. Layer 18 is positioned over the fluid sealing material and has channel 16 and opening 19 formed therein. Channel 16 extends longitudinally along the strip to direct fluid toward the capture region of the device. Generally the channel is constructed of sufficient dimension and configuration to allow sufficient fluid flow without fluid leakage out of the sides or without exhibiting clogging or clumping, as might otherwise occur with more viscous samples, such as blood. Although FIG. 1 shows channel 16 being somewhat narrower than opening 19, it is contemplated herein that channel 16 could be the same width or even wider than opening 19. Alternatively, channel 16 could have a wider opening distal to the sample receiving port than its width proximal to the sample receiving port. This variation could be particularly useful in the case where clotting or clumping of the sample is of concern.

Once built up in layers, the sample receiving port is formed. The port provides fluid communication with the channel, and the channel provides fluid communication with the analytical membrane. Next hydrophilic material 20 is positioned over layer 18, the hydrophilic material having an opening therein corresponding to opening 19, but covering channel 16. Gasket element 22 is positioned over hydrophilic material 20 and has an opening therein corresponding to opening 19 to allow fluid entry into the port. The gasket provides a fluid seal between the assay and any surrounding housing.

In various embodiments described herein, the housing is made up of bottom housing portion 8 which supports support member 11. As shown in FIG. 3 it also preferably has side tabs 6 for proper placement in a magnetic reader device. Bottom housing portion 8 is generally configured in a C-shape, the open side being designated by reference numeral 46. FIG. 4 shows the underside of top housing portion 42. It is generally complementary in configuration to the bottom housing portion. Therefore, it is also in a C-shape configuration. The top housing fits over the bottom housing such that test strip 12 spans opening 46 of the C-shape, as shown in the assembled device of FIG. 5. Thus, a magnetic reader device can access test strip 12 from the top and bottom surface at the same time. FIG. 2 shows a sectional side view of assembled test strip 12. Wicking pad 26 is present on one end, as well as protective membrane 24, which covers analytical membrane 14.

Since test strip 12 spans opening 46 of the assembled housing portions, and since it is placed in the gap of a magnetic reader device, it is of concern that the test strip be properly anchored within the housing so as to avoid flexing or movement of the strip with relation to the housing portions. It is also important that the relative positions of the control line, index line, and result lines be maintained. Accordingly, the embodiments of the present invention have gripping and tensioning aspects to control these effects.

With reference again to FIG. 3, bottom housing portion 8 is shown in a perspective view. Although not shown in this view, test strip 12 is dropped into trough 56. Preferably the width of the trough will accommodate the width of the strip without binding or without undesired lateral movement. Cross channels 58 are present in the bottom of trough 56. There are preferably two such cross channels closely spaced at one end, and one cross channel at the other end of the trough. Also at one end of the trough there is sloping cross channel 59. These channels are configured to accommodate corresponding features on the underside of top housing portion 42 when assembled. Accordingly, the assembly thereof provides a gripping and tensioning aspect to the test strip.

As shown in FIG. 4, the underside of top housing portion 42 has pegs 64, two on one end, and one on the other end of the device. Also on one end of the device is tensioner 62. Tensioner 62 is shown with a downward sloping face and a scalloped or ridged protruding edge. This edge contacts the test strip and provides an appropriate degree of tension without causing deformation or tearing of the strip. The configuration shown is by way of example and the tensioner may have other equally effective shapes.

Other features of the device are directed toward preventing movement of the strip in relation to the magnetic field. For example, bottom housing portion 8 has securing holes 54 for receiving securing pins 65 on top housing portion 42. The relatively large diameter of the hole and pin secures the parts together to prevent undesired warping or bending of the housing components once assembled. Also it can be seen in FIG. 3 that assembly holes 53 in the bottom housing portion are configured to receive assembly pins 67 in the top housing portion, preferably with a compression fit.

As mentioned above, FIG. 5 shows an embodiment of the device fully assembled. Test strip 12 is shown spanning opening 46. Barcode label area 47 on top housing portion 42 provides information that the magnetic reader device uses in the assay, such as calibration and positional information. It also may provide information regarding the nature of the particular test or sample being tested for.

It should be observed that while the above description generally relates to quantitative detection of target analytes in a directed flow immunoassay, the invention can equally be used for receptor assays, cellular assays, or molecular assays.

Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A directed flow assay device for quantitative detection of target analytes in a sample, said device comprising: an assay support member having a first end and a second end;a porous analytical membrane mounted adjacent to and generally parallel with said support member, said analytical membrane having a first end and a second end and at least one capture region intermediate said first and second ends thereof, said at least one capture region being configured to capture labeled analytes moving from said first end of said analytical membrane toward said second end of said analytical membrane; anda sample receiving port at one end of said support member for introduction into said device of the sample to be analyzed, said sample receiving port comprising: a channel layer positioned above said sealing material, said channel layer comprising an opening and a channel, said opening providing fluid communication with said channel, and said channel providing fluid communication with said porous analytical membrane;a hydrophilic material positioned over said channel layer, said hydrophilic material having an opening therein corresponding to said opening in said channel layer; anda gasket element positioned over said hydrophilic material and having an opening therein to allow fluid entry into the port, said gasket providing a fluid seal for the assay device.

2. The device recited in claim 1, and further comprising a protective membrane covering said analytical membrane on the side opposite to said support member, said protective membrane being optically non-transparent.

3. The device recited in claim 2, wherein said protective membrane is formed integrally with said porous membrane.

4. The device recited in claim 1, and further comprising a control region in said porous membrane for collection of conjugates that have passed the capture region to show that said test strip has been used.

5. The device recited in claim 4, and further comprising at least one magnetic calibration area printed on said protective membrane.

6. The device recited in claim 1, and further comprising a fluid sealing material between said assay support member and said channel layer.

7. An analytic apparatus for quantitative detection of target analytes in a sample, said apparatus comprising: a test strip comprising: an assay support member having a first end and a second end;a porous analytical membrane mounted adjacent to and generally parallel with said support member, said analytical membrane having a first end and a second end, a capture region in said analytical membrane intermediate to said first and second ends of said analytical membrane, said capture region being configured to capture labeled analytes moving from said first end of said analytical membrane toward said second end of said analytical membrane;a sample receiving port at one end of said support member for introduction into said device of the sample to be analyzed, said sample receiving port comprising:a channel layer positioned above said sealing material, said channel layer comprising an opening and a channel, said opening providing fluid communication with said channel, and said channel providing fluid communication with said porous analytical membrane; a hydrophilic material positioned over said channel layer, said hydrophilic material having an opening therein corresponding to said opening of the channel layer; anda gasket element positioned over said hydrophilic material and having an opening therein to allow fluid entry into the port;a bottom housing portion for supporting the support member, said housing generally configured in a C-shape; anda top housing portion generally complementary in configuration to said bottom housing, said top housing fitting over said bottom housing such that said test strip spans the opening of the C-shape, said gasket element providing a fluid seal between said sample receiving port and said housing.

8. The apparatus recited in claim 7, and further comprising a protective membrane covering said analytical membrane on the side opposite to said support member, said protective membrane being optically non-transparent.

9. The apparatus recited in claim 8, wherein said protective membrane is formed integrally with said porous membrane.

10. The device recited in claim 7, and further comprising a control region in said porous membrane for collection of conjugates that have passed said capture region to show that said test strip has been used.

11. The device recited in claim 10, and further comprising at least one magnetic calibration area printed on said protective membrane.

12. The apparatus recited in claim 7, wherein said bottom housing portion is shaped and configured for dropping in said support member and analytical membrane with the sample receiving port.

13. The device recited in claim 7, and further comprising a fluid sealing material between said assay support member and said channel layer.

14. A method for quantitative detection of target analytes in a sample by means of a directed flow immunoassay, a receptor assay, a cellular assay, or a molecular assay, the method comprising: coupling superparamagnetic particles with said sample, the superparamagnetic particles being treated to bind with the target analyte in the sample, said coupling producing a conjugate;applying the conjugate to one end of a porous membrane of a test strip by means of a sample receiving port that is located on the test strip, the test strip having a capture region;capturing the conjugates in the capture region of the porous membrane as the conjugates move through the porous membrane by capillary action; andreading the quantity of labeled analytes in the capture region by means of a magnetic assay reader device.