Capillary immunoassay and device therefor comprising mobilizable particulate labelled reagents

An analytical test device comprising a hollow casing constructed of moisture-impervious solid material containing a dry porous carrier which communicates directly or indirectly with the exterior of the casing such that a liquid test sample can be applied to the porous carrier, the carrier containing in a first zone a labelled specific binding reagent for an analyte or which can participate in a competition reaction in the presence of an analyte, which labelled specific binding reagent is freely mobile within the porous carrier when in the moist state, and in a second zone spatially distinct from the first zone unlabelled specific binding reagent for the same analyte which unlabelled reagent is permanently immobilised on the carrier material and is therefore not mobile in the moist state, the two zones being arranged such that liquid sample applied to the porous carrier can permeate via the first zone into the second zone, and the device incorporating means enabling the extent (if any) to which the labelled reagent becomes bound in the second zone to be observed.

A test device according to any one of the preceding claims, within the porous carrier communicates with the exterior of the device via a bibulous sample receiving member which protrudes from the casing and which can act as a reservoir to receive the liquid sample and release it into the porous carrier.

A test device according to any one of the preceding claims, within the casing, and cover if present, is molded from plastics material.

A test device according to any one of the preceding claims, wherein the porous carrier comprises a strip or sheet of porous material backed with a layer of transparent moisture-impervious material, the transparent layer being in contact with the inside of the casing adjacent the aperture(s) to inhibit ingress of moisture or sample.

A test device according to any one of the preceding claims, wherein the label comprises colored latex particles having a maximum dimension of not greater than about 0.5 micron.

A test device according to any one of the preceding claims, incorporating a control zone downstream from the second zone in the porous carrier to indicate that the liquid sample has permeated beyond the second zone, the control zone also being observable from outside the casing.

A test device according to any one of the preceding claims, wherein the analyte is hCG.

A pregnancy testing device comprising a hollow elongated casing containing a dry porous nitrocellulose carrier which communicates indirectly with the exterior of the casing via a bibulous urine receiving member which protrudes from the casing and which can act as a reservoir from which urine is released into the porous carrier, the carrier containing in a first zone a highly-specific anti-hCG antibody bearing a colored “direct” label, the labelled antibody being freely mobile within the porous carrier when in the moist state, and in a second zone spatially distinct from the first zone an highly-specific unlabelled anti-hCG antibody which is permanently immobilised on the carrier material and is therefore not mobile in the moist state, the labelled and unlabelled antibodies having specificities for different hCG epitopes, the two zones being arranged such that a urine sample applied to the porous carrier can permeate via the first zone into the second zone, and the casing being constructed of opaque or translucent material incorporating at least one aperture through which the analytical result may be observed, together with a removable and replaceable cover for the protruding bibulous urine receiving member.

A specific binding assay involving the use of a labelled reagent which is free to migrate through a porous carrier material moistened by the application thereto a an aqueous sample suspected of containing an analyte, wherein the label is a direct label.

An analytical test device substantially as hereinbefore described with reference to FIGS. 3 to 5.

An analytical test device substantially as hereinbefore described with reference to FIGS. 6 and 7.

An analytical test device substantially as hereinbefore described with reference to FIGS. 8 and 9.

An analytical test device incorporating a test strip substantially as hereinbefore described with reference to FIG. 10.

An analytical test device substantially as hereinbefore described with reference to FIGS. 11 and 12.

An analytical test device substantially as hereinbefore described with reference to FIGS. 13 and 14.