WO2013171446A2

WO2013171446A2 - Saliva testing

Info

Publication number: WO2013171446A2
Application number: PCT/GB2013/000226
Authority: WO
Inventors: Peter William Dettmar; Jonathan Richard Flint
Original assignee: Technostics Limited
Priority date: 2012-05-17
Filing date: 2013-05-17
Publication date: 2013-11-21
Also published as: CN104471399B; WO2013171446A3; GB2518311A; GB2518311B; GB201208663D0; CN104471399A

Abstract

The present invention relates to a device for testing an oral fluid such as saliva and methods of using said device, the device comprising an absorbent lateral test strip having a sample portion for receiving a sample to be tested and a test portion for visualising the test results, the sample portion including a filter pad through which, in use, the saliva passes before reaching the test portion, the filter pad having a thickness of at least 0.5 mm.

Description

SALIVA TESTING

FIELD OF THE INVENTION

The present invention relates to devices and methods for carrying out assays on saliva samples and in particular to lateral flow devices and methods.

BACKGROUND TO THE INVENTION

Lateral flow devices are used in assays and are simple devices intended to detect the presence (or absence) of a target in a sample. The lateral flow devices may be used in a wide variety of applications including pregnancy tests, HIV tests and malaria tests. The test can be applied to ,for instance, urine, saliva, blood or stool samples.

EP1277053 discloses a method and device for diagnostic testing of an oral fluid, including saliva. This patent is concerned with a problem encountered with the testing of saliva which is that the saliva sample does not run along the lateral flow test strip. The inventors of EP 1277053 believed that this was due to the relatively high concentrations of mucin and other viscous, proteinaceous materials in the specimen. The inventors proposed including in the device a pad having deposited thereon a salt or other known mucinolytic substance known to break down and lower the viscosity of mucin-containing fluids. The pad is composed of a glass of fibre matrix which provides means for filtering the disassociated proteinaceous and other particulate material from the specimen. The device is stated to allow convenient and rapid testing of a relatively small saliva sample without any need to pre-treat the saliva in order to enable its migration along the test strip.

The fibre pad specified in EP1277053 comprises a die-cut portion of a commercially available glass fibre material having a thickness of about 0.2 mm. The pad is placed on a conjugate pad which has a detector reagent deposited thereon. The saliva specimen is placed on the glass fibre salt pad which breaks down mucin substances which are subsequently filtered by the glass fibres in the salt pad as well as in the underlying glass fibre sample pad. The specimen sample then passes through the conjugate pad where a chemical reaction begins if the analyte is present in the specimen. The specimen sample then passes into capture zones where the test result can be read.

The inventors of the present invention have discovered that, for the purposes of certain saliva assays, including a pepsin assay, the saliva runs along the lateral flow test strip sufficiently well to enable test results to be obtained. However in perhaps about 10% of tests the saliva does not run sufficiently well. The reason for this is not clear. However the inventors have discovered that the use of a relatively thick filter, compared to that suggested in EP1277053, enables the saliva to run sufficiently well for meaningful test results to be obtained. Accordingly it is not necessary to have the saliva pass through a pad which is loaded with a material capable of dissociating proteinaceous materials, for example, a salt.

STATEMENTS OF THE INVENTION

According to the present invention there is provided a device for testing an oral fluid such as saliva, the device comprising an absorbent lateral flow test strip having a sample portion for receiving a sample to be tested and a test portion for visualising the test results, the sample portion including a filter pad through which, in use the saliva passes before reaching the test portion, the filter pad having a thickness of at least 0.5 mm.

The present invention also provides a method for carrying out a diagnostic test of an oral fluid specimen, the method comprising providing a device as claimed in any of the preceding claims, depositing an oral fluid specimen on the sample portion and visualising the test results provided on the test portion.

Preferably, the device includes a housing accommodating a diagnostic strip providing said sample and test portion. Preferably, the sample portion is located at one end of the diagnostic strip.

Preferably, an absorbent portion is located at the other end of the diagnostic strip. Preferably, the filter pad is a binder-free fibre pad. More preferably the fibre pad is a glass fibre pad, most preferably a micro-glass pad.

Preferably, the fibre pad is formed from a borosilicate micro-glass.

Preferably, the sample portion includes a backing substrate to which the fibre pad is adhered. More preferably, the backing substrate is an adhesive polystyrene.

Preferably the thickness of the filter pad is at least 0.7 mm, more preferably between 0.75 mm and 1 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are as follows: Figure 1 shows two lateral flow devices (LFD), the upper LFD not including a filter pad and the lower LFD including a filter pad; and

Figure 2 shows LFDs as in Figure 1 but without their housings. DETAILED DESCRIPTION OF THE INVENTION

Referring to Figure 1 of the accompanying drawings, lateral flow devices 1 comprise a lateral flow assay housed within a plastic housing 3 including a sample well 5 for receiving a saliva specimen. A diagnostic strip 7 accommodated within the housing comprises a sample reception portion, a test portion for visualising the test results and an absorbent portion at the end remote from the sample reception portion.

At the sample end of the lower LFD, a binder-free borosilicate micro-glass fibre pad is located directly beneath the sample well 5 and adhered to an adhesive polystyrene backing substrate. The micro-glass fibre pad has a basis weight of 120.4 gm², a thickness 0.85 mm and a Frazier permeability of 75.2 L/m²/sec. An example of a suitable fibre pad is a Grade 142 pad made by Ahlstrom.

The fibre pad facilitates the slow filtration, transition and migration of the sample to the adjacent glass fibre conjugate pad, with which it is in communication. The resultant "treated" saliva rehydrates the immobilised polystyrene labels following which there is migration to the nitrocellulose membrane test region.

As the saliva migrates through the fibre pad via capillary action, any particulates are filtered out by sized selection. Transition of other salivary components is regulated and the treated sample is slowly and consistently released on to the conjugate pad. Upon transition to the test region and ultimately the absorbent zone, the saliva is drawn through by continued capillary action. It is believed that the pad sufficiently modities the sample such that those of "problematic" individuals are regulated to behave and therefore flow through the interstitial spaces of the membranes in the same manner as for a "non-problematic" specimen, resulting in identical assay performance. Figure 1 shows the results of an assay of the saliva of a "problematic" specimen. It can be seen that, in the other LFD, no control line appears in the window 7. In Figure 2, which shows the same LFDs but with the housings removed, it can be seen that, in the upper LFD, the 80 μΐ saliva sample has agglutinated and not flowed.

Claims

1. A device for testing an oral fluid such as saliva, the device comprising an absorbent lateral test strip having a sample portion for receiving a sample to be tested and a test portion for visualising the test results, the sample portion including a filter pad through which, in use, the saliva passes before reaching the test portion, the filter pad having a thickness of at least 0.5 mm.

2. A device according to claim 1 and including a housing accommodating a diagnostic strip providing said sample and test portion.

3. A device according to claim 2, wherein the sample portion is located at one end of the diagnostic strip.

4.^' A device according to claim 2 or claim 3, wherein an absorbent portion is located at the other end of the diagnostic strip.

5. A device according to any of the preceding claims, wherein the filter pad is a binder-free fibre pad.

6. A device according to claim 5, wherein binder-free fibre pad is formed from a micro-glass pad.

7. A device according to claim 6, wherein the binder-free fibre pad is a borosilicate micro-glass.

8. A device according to any of the preceding claims, wherein the sample portion includes a backing substrate to which the fibre pad is adhered.

9. A device according to claim 8, wherein the backing substrate is an adhesive polystyrene.

10. A device according to any of the preceding claims, wherein the thickness of the filter pad is at least 0.7 mm.

11. A device according to claim 10, wherein the filter pad has a thickness between 0.75 mm 1 mm. 12 A device according to Claim 1 and substantially as described herein. 13. A device for testing an oral fluid such as saliva, the device being substantially as described herein with reference to the accompanying drawings. 14. A method for carrying out a diagnostic test of an oral fluid specimen, the method comprising providing a device as claimed in any of the preceding claims, depositing an oral fluid specimen on the sample portion and visualising the test results provided on the test portion.