CA2237395A1

CA2237395A1 - Diagnostic test apparatus

Info

Publication number: CA2237395A1
Application number: CA002237395A
Authority: CA
Inventors: Michael John Chard; Robert Woolston; Bernard Sams; Christopher John Smith; Philip Robert Goodwin
Original assignee: Individual
Current assignee: Cortecs Ltd
Priority date: 1995-11-13
Filing date: 1996-11-13
Publication date: 1997-05-22
Also published as: JP2000500671A; EP0861123A1; AU731250B2; KR19990067532A; US6241689B1; TW368400B; NZ322108A; BR9611461A; WO1997018036A1; NO982156L; NO982156D0; AU7577696A

Abstract

Sample collection apparatus (101, 101a) is provided which allows for fast, accurate, repeatable sample collection, particularly of blood and saliva samples. This apparatus is adapted to interconnect with a device (106) designed to carry out analyte detection. Kits comprising the sample collection apparatus (101, 101a) are also provided.

Description

CA 0223739~ 1998-0~-12 WO 97/18036 PCT/GB9l~/02751 DIAGNOSTIC TEST APPARATIJS

The present invention relates to apparatus for use in collecting liquid samples, in particular biological samples, e.g blood or saliva. ~uch apparatus is useful in collecting samples for use in diagnostic tests, and the invention also provides a kit for use in such tests.

Increasingly, use is being made of rapid diagnostic tests, both for use at home by a patient or for use by doctors in their surgeries. These tests have been made available through the use of diagnostic test devices and/or kits which provide everything needed to collect a sample and to perform the diagnostic test thereon. This enables many such tests to be performed more rapidly with less fuss and inconvenience. One example of such a test is the HE~ISALTM test used to diagnose infection by H.pylori using a sample of blood.

Of course, such tests, and the test devices/kits provided to per~orm them, must be capable of providing the required level of accuracy that hospital laboratories can achieve, or at least a level of accuracy approaching that of hospital laboratories. In addition, it is often the case that the sample size required for the test fall within a particular range. For home use, and even for use by a doctor in the surgery, accurate measurement of sample volume may present problems. In addition, handling of samples which may represent a "biohazard" can be difficult. Thus, what is required is some form of apparatus which will allow collection of a sample in the right volume range, while at the same time min;m~sing the risk of contact with the sample by the user.

CA 0223739~ 1998-0~-l2 In general, at present, samples are first collected and then transferred to a means, be it a device or the like or a simple test strip, where the test is performed. For example, to perform a test on a sample of blood, the person performing the test might prick the subject's finger and then use a simple capillary to draw up a sample of blood. This sàmple would then be trans~erred to the device or test strip for the reaction to occur.
Clearly, it would be better if one could provide a sample collection apparatus which would accurately take up a "fixed~' volume o~ sample and which would then release the sample in such a way that the sample is made available accurately and quickly every time, thus ensuring accurate and repeatable results.

We have now devised such an apparatus. This is simple to use, can be adapted easily to collect different types of sample as well as different sample sizes and which also m; n; m~ ses the risk of user contact with the sample, particularly when transferring the sample to a device designed to perform a diagnostic test on the sample. In particular, the apparatus is designed to connect with a device or housing which incorporates an analyte detection means. The connection of the two parts ensures that the sample is accurately presented each time a test is per~ormed such that the sample can be quickly and accurately transferred to the detection means.

Thus, in a first aspect, the present invention provides sample collection apparatus adapted to interconnect with a device or housing which incorporates analyte detection means, wherein upon interconnection with said device or housin~ the sample is presented such that at least a part of any sample in the apparatus will be transferred to the CA 0223739~ 1998-0~-12 WO97/18036 PCT/G~96/02751 device or housing from the apparatus. Suitably, the apparatus comprises a first portion adapted to be held by the user while collecting the sample, and a second portion comprising sample collection means.

The apparatus could be designed to simply be pushed together with the device or housing incorporating the analyte detection means. However, in one embodiment, the apparatus further comprises alignment means adapted to ensure correct presentation o~ the sample collection apparatus upon interconnection with the device or housing. One example of such alignment means would be guide rails, or projections designed to align with recesses formed in the device or housing. Furthermore, the alignment means could itself act as interconnection means.

In one preferred embodiment, which is particularly suited to collecting blood samples, the sample collection means comprises a~ least two members adapted to receive a sample volume therebetween upon bringing the members into contact with a liquid. In particular, the apparatus will work by taking up the sample by capillary action, simply by bringing the members into contact with the sample.
Preferably, the members are elongate and could, for instance, be formed by plates, or could form a comb arrangement. In another arrangement there could be provided a two-~im~n~ional arrangement of members with spaces therebetween. The apparatus can easily be adapted to collect particular volumes of sample, simply by means of altering the volume of the spaces between the members.
Preferred embodiments include four, five or six elongate members in a comb arrangement providing three, ~our or five spaces therebetween, respectively, to receive the CA 0223739~ 1998-0~-12 sample volume.

The exact nature and arrangement of the members is not critical. However, clearly, one would not construct the members of a hydrophilic material. Also, the spacing between the members should be such that the sample will be taken up and held between the members. If the spacing is too great, this will not occur. The essential ~eature which the arrangement must possess is the ability to both present the liquid sample accurately and allow it to be released quickly and reliably. One example of how this can be achieved would be by having an arrangement o~ the collection means such that contact over a substantial proportion o~ its surface area with part of the device or housing was achieved upon interconnection. For example, one arrangement would provide ~or contact of the sample collection means with a test strip, usually formed of porous material, or with an intermediate member, formed o~ porous material and designed to take up the sample and transfer it to where the reaction is to be performed, upon interconnection.

It may also be advantageous to coat the sample collector with a substance such as heparin to reduce or eliminate blood clotting.

In an alternative preferred embodiment, which would be particularly suited to collecting saliva samples, the sample collection means is formed from a body of absorbent material. An example of a suitable material is absorbent material comprising one or more sintered polymers. Useful polymers include plastics, such as sintered polyethylene (PE).

CA 0223739~ 1998-0~-12 This material is bio-compatible, does not fragment, break, deform, etc., and is also able rapidly and consistently to absorb liquid. In addition, it has a controlled pore size, and in this way the material can be formed such that it will readily transfer/give up absorbed material to "downstream" components in any diagnostic kit. Pore size can be controlled in a number of ways. Firstly, polmer powders of different mean particle sizes can be used. I~ a polymer powder is not available which has exactly the required pore size, then a powder with a larger mean pore size can simply be ground to the desired particle size. Polymer powders having a mean particle size within the range 20-500 microns are particularly useful.

Another way of controlling particle size is by adjustment of the packing of the polymer powders in the mould before sintering. However, using this method, it is only possible to alter pore size to a smaller degree.

To ensure good uptake of a hydrophilic liquid li~e saliva, relatively hydrophilic polymers can be used.
However, relatively non-hydrophilic polymers can be treated to increase their hydrophilicity. Such treatment can be carried out either before or after the sintering process. Examples of such treatment include treatment with a sur~ace-active/wetting agent, e.g. Sodium Dodecyl Sulphate (SDS) or more preferably a biocompatible agent such as Crodasinic LS30, chemical, electrical or radiation treatment, thereby modifying the sur~ace of the material.

To produce such an absorbent material, one or more polymer powders are mixed in a mould. Filling of the CA 0223739~ 1998-0~-12 mould can be achieved with or without the help of mechanical vibration, this being dependent on the degree of packing required.The mixture is then heated in the mould to a sintering temperature, ie one greater than the melting point of the polymer such that the particles of polymer melt and adhere together but not sufficient to flow sufficiently that the porous nature of the material is lost.

The degree of heating above the melting point of the polymer or polymers that can be achieved will depend upon the melt viscosity of the polymer or polymers. If a polymer with a high melt viscosity is chosen then the sintering temperature used can be much higher than the melting temperature. However, if the melt viscosity is low, then the sintering temperature must be very carefully controlled close to the melting point of the polymer.

The mould can be constructed of any suitable material having good thermal conductivity. The mould will be held at the desired temperature until the polymer or polymers have fused satisfactorily. The mould is then cooled and the absorbent material can be removed from the mould.

Suitably, the material can be formed into a pad or swab which would be convenient for obtaining a sample of saliva, for example. The material is easy to handle and works with and lends itself to being formed with a particular configuration.

In a ~urther embodiment apparatus is provided which r allows the user to choose different types of collection member which can be attached to the ~irst, "handle 1l ~ , , CA 0223739~ 1998-0~-12 portion.

For example, the apparatus could be provided as a kit, providing the first portion as "standard" as well as a number of di~erent collection members. The different collection members could simply be various comb devices designed to collect di~ferent sample volumes.
Alternatively, a comb member could be provided and also, for instance, a pad of absorbent material as described herein. The user would then be able to choose the appropriate collection member for the sample to be collected.

The apparatus can be used, therefore, to collect a fixed volume of sample. In the context of the present invention, "fixed" will generally mean a volume falling within a suitable range for use in the test in which the sample volume is to be used. Absolute accuracy will not be required, just sufficient accuracy to ensure that there is su~ficient material present for the purposes of any test to be performed on the sample. For example, where a diagnostic test device is to be used, the sample should be sufficient to ensure that the device is not "under" or "over" loaded.

Thus, in the case o~ a ''comb'l type device the spaces between the members will de~ine the sample volume and the user simply has to ensure that the spaces between the members are fully occupied with sample. In the case of apparatus incorporating absorbent material it may be useful to include some form of "adequacy" indicator which will allow the user to be certain that a large enough saliva sample, for instance, has been collected. Thus, one could incorporate a food dye, eg a blue food dye, in CA 0223739~ 1998-0~-12 that part o~ the absorbent material nearest the handle portion o~ a collector device. Once a liquid sample reaches the dye it will be solubilised and be dispersed (indeed the handle portion could be hollow at least in part to receive the solubilised dye) thus indicating that a sufficient sample has been collected.

The apparatus of the invention can be made of any suitable material, subject of course to the necessity of providing some form o~ absorbent member, where appropriate. Such materials will include those that can be moulded in the desired configuration. Materials which can be machined or carved to the desired con~iguration would also be suitable. Examples of such materlals would be conventional plastics materials used in this art and known to the skilled man.

As discussed herein the apparatus o~ the invention will present the sample accurately when interconnected with the device or housing such that the sample will be released or transferred when brought into contact with suitable means. Suitably, there~ore, the device or housing incorporating the analyte detection means will include means for trans~erring the sample to the device or ~it. In this way, the ~ixed sample volume will be released from the apparatus such that the analyte detection process, eg diagnostic test, can begin.

In a second aspect, the present invention provides a ~it ~or the detection o~ an analyte in a sample which comprises:

~i) sample collection apparatus as de~ined herein;
and CA 0223739~ 1998-0~-12 WO97/18036 PCT/GB96/~2751 (ii) means for detecting the analyte.

Suitably, the means for detecting the analyte will comprise:

(i) a reaction area; and (ii) means for transferring the sample to the reaction area.

Suitably, the reaction area is located on a strip of suitable material, eg nitrocellulose, nylon or the like.
The means for transferring the sample to the reaction area could be a porous or bibulous material such as a filter paper or the like. When the kit is to be used to detect an analyte in a blood sample it will be usual to first separate the red blood cells from the blood plasma since it is often the case that the analyte is present in the plasma only. Thus, the apparatus can further comprise means for separating the blood cells from the blood plasma. This would also be useful in preventing any interference in visualising any colour reaction used to detect the analyte. In one embodiment, the means for transferring the sample to the reaction area also serve to separate the red blood cells from the blood plasma.

In general the reaction area will have ~ixed thereto one or more agents capable of binding to the analyte. For instance, where the analyte to be detected is an antibody, the reaction area can have fixed thereto one or more binding partners for the antibody, for instance, one or more antigens capable of binding to the antibody.
Alternatively, where the analyte to be detected is an antigen, the reaction area can have fixed thereto one or CA 0223739~ 1998-0~-12 WO97/18036 PCT/GB96/~2751 more binding partners for the antigen, eg antibodies capable of binding to the antigen.

In a particularly preferred embodiment, the analyte to be detected allows detection of the presence of H. pylori i.e. where the analyte is an antigen, it is one derived from H~ pylori, or when the analyte is an antibody, it is one which binds to at least one antigen derived ~rom ~.
pyl ori .

Preferably, the apparatus and the analyte detection means will be adapted to interconnect such that, once connected, they cannot be disconnected thus ensuring that no leakage of the sample occurs. In use, there~ore, the sample volume will be taken up by the sample collection apparatus. The apparatus will then be interconnected with the analyte detection means. The sample will be presented such that it then passes from the apparatus to the analyte detection means, and thus to the reaction area. Finally, visualisation of the test result will occur.

In other aspects, the present invention provides:

(a) the use of apparatus of the invention in collecting a sample volume, particularly of blood or saliva;

(b) the use of a kit of the invention in detecting an analyte in a sample, particularly in a blood or saliva sample; and ~c) a method for detecting an analyte in a sample which comprises the step o~ collecting -CA 0223739~ 1998-0~-12 -WO97/18036 P~T/GB96/~2751 a sample volume ~sing apparatus of the invention, preferably provided as part of a kit o~ the invention. In one embodiment of this aspect the method i9 used to detect an analyte in a blood or saliva sample, particularly for use in dia~nosing H. pylori infection.

Preferred embodiments of the invention will now be described with reference to the accompanying drawings in which:-FIGURE l: shows one embodiment of the samplecollection apparatus;

FIGURE 2: shows the sample collection apparatus of Figure l, together with a form of analyte detection means;

FIGURE 3: shows the sample collection apparatus o~ Figure l together with a sectional view of analyte detection means.

FIGURE 4: shows alternative embodiments of the sample collection apparatus showing both a "blood" collector and a "saliva" collector together with an alternative form of analyte detection device; and FIGURE 5: shows the "blood" collector of figure 4 together with a sectional view of an alternative form of analyte detection device.

Figure l shows one embodiment of the sample collection apparatus of the invention. The apparatus (l) consists CA 0223739~ 1998-0~-12 of a first portion (2) which is designed to be held by the user, and a second portion (3) which is used for sample collection. Part o~ the second portion (3) is t formed of a number of elongate members (4) which define a series of spaces (5) therebetween. In use, the second portion (3) can be placed in contact with a liquid, e.g.
blood. A sample volume o~ the li~uid will flow into the spaces (5) by means of capillary action.

In Figure 2, the apparatus (1) is shown next to a form of device (6) suitable for detecting an analyte in a sample.
It can be seen that the second portion (3) of the sample collection apparatus (1) can be inserted into an opening (7) formed in the device (6). Thus, in use, the collection apparatus (1) carrying the sample can be connected to the device (6) by inserting its second portion (3) into the opening (7~. The sample can then be transferred to a nitrocellulose strip (8), at least part of which constitutes the reaction area, which can be seen via a window (9) cut in the upper surface (10) of the device (6). Thus, the result of the test can be visualised via the window (9). The embodiment shown also provides a re~erence area (11) which can be seen by means of a second window (12) cut in the upper surface (10) of the device (6).

Such a reference area can provide a background to assess the result in the reaction area (8) when visualisation occurs by means of a colour reaction. Alternatively, this area can constitute a "test complete" areaA This will allow the user to be sure that sufficient material was loaded for a reliable test result to have been achieved.

In Figure 3, the device (6) is shown in longitudinal CA 0223739~ l998-0~-l2 section, thus showing the internal construction more clearly. In use, the sample collector (1) is attached to the device (6) by inserting its second portion (3) into ~ the opening (7) provided in the device (6). Once inserted, the sample volume held in the spaces (~) between the elongate members (4) contacts a mem~er comprising a porous/bi~ulous material (13). This member will serve to transfer the sample ~rom the collection apparatus to the nitrocellulose strip (8). In addition, where the sample is a blood sample, it will also serve to separate the blood cells ~rom the blood plasma. The lower surface of the member (13) is in contact with the upper surface o~ the nitrocellulose strip (8), and so the sample will move generally along and down from the member (13) into the nitrocellulose strip (8) and will be drawn along it.

The whole of the nitrocellulose strip (8) could constitute the reaction area, or, more usually, only a portion will, and ~ixed to it will be one or more agents capable of binding to the analyte if present in the samples.

For example, in a test for the presence of antibodies to H. pylori in a blood sample, at least a portion of the nitrocellulose strip (8) will have fixed to it one or more antigens derived from H. pylori. ~s the sample passes through the strip (8), any H. pylori antibodies present in the sample will bind to the fixed antigen(s).
The test results can then be read by, ~or instance, adding to the nitrocellulose strip (8) an agent capable of binding to antibodies generally (for example an anti-IgG antibody) which in turn is bound to a colour reagent, ~or instance a coloured latex particle. Thus, where the CA 0223739~ l998-0~-l2 Wo97/18036 PCT/GB96/02751 antibodies for the sample have bound to the antigen, a concentration of colour will occur.

A further refinement of the device (6) will be to provide a control area. The control area could be provided adjacent to the reaction area. In this control area can be bound a reference agent. In use, the control area can be designed to bind any colour reagent which passes through the reactlon area, but is not bound thereto. In this way, the test can be assessed by the binding of this "excess" reagent to the control area.

This control area thus allows the user to ensure that the test is operating correctly and eliminates false negatives.

Figure 4 shows an alternative embodiment of a "blood"
collector (101) as well as a form of collector (lOla) which comprises a body of absorbent material as described herein. Once again the collector (101/lOla) has a first portion (102/102a) which can be held by the user, and a second portion (103/103a) which is used ~or sample collection. In the case of the ~blood" collector (101) there is an elongate member (113) located between the first portion (102) and the collector portion (103). That part of the collector portion (103) which is designed to take up the sample consists of a number of elongate members (104) which define spaces (105) therebetween. Use of such a collector is as described ~or the collector apparatus described in figure 1.

The "saliva" collector (lOla) is formed from a first portion (102a) which is designed to be held by the user, and a second portion (103a) formed from a body of CA 0223739~ l998-0~-l2 absorbent material.

The device (106) suitable ~or detecting an analyte in the sample is adapted to receive the collector (101/lOla) via an opening (107). The result o~ the diagnostic test is read via a window (109) cut in the upper surface (llO) of the device (106).

In figure 5 the device (106) is shown in longtitudinal section with a "blood" collector (101). Th ~igure shows more clearly how the collector (lol) can interact with the device (106) releasing the sample held in the collector portion (103) formed by the elongate members (104). When the collector is inserted into the device (106) via the opening (107) the collector portion (103) and then the elongate member (113) are guided by rails (115). The collector (101) also has engagement means (117) which engage counterpart means (116) which are present in the device (106). These engage and hold the collector (lol) in place with the elongate member (113) and collector portion (103) projecting into the interior o~ the device (106) such that the elongate members (104) are in contact with a bibulous member (114) which in turn is in contact with a nitrocellulose strip (108). Thus, the sample will move through the bibulous member (114), which can also be adapted to separate blood cells ~rom the accompanying plasma, into the nitrocellulose strip (108) where the diagnostic assay commences.