Bidirectional lateral flow test strip and method
First Claim
1. A test strip adapted to receive a sample and detect an analyte therein, the test strip comprising:
- a sample addition zone to which a sample may be added;
an absorbent zone positioned on the test strip in a first flow direction relative to the sample addition zone, wherein the absorbent zone comprises an absorbent pad that is affixed to the test strip;
one or more test zones positioned on the test strip in a second, different flow direction relative to the sample addition zone, at least one of the test zones including a first analyte binding agent immobilized therein which is capable of binding to the analyte to be detected, the absorbent pad being in fluid communication with the sample addition zone and having an absorption capacity relative to the other zones of the test strip such that when a volume of sample within a predetermined sample volume range for the test strip is added to the sample addition zone, the sample initially diffuses from the sample addition zone both in the first flow direction to the absorbent zone and in the second flow direction past the one or more test zones and then reverses flow, and diffuses in the first flow direction past the one or more test zones toward the absorbent zone; and
a conjugate buffer addition zone positioned on the test strip in the second flow direction relative to where the sample reverses flow, such that when conjugate buffer is added to the conjugate buffer addition zone, the conjugate buffer diffuses in the first flow direction past the one or more test zones.
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Accused Products
Abstract
A test strip adapted to receive a sample and detect an analyte therein is provided. The test strip comprises a sample addition zone to which a sample may be added; an absorbent zone proximal to the sample addition zone; one or more test zones distal to the sample addition zone, at least one of the test zones including a first analyte binding agent immobilized therein which is capable of binding to the analyte to be detected; and a terminal sample flow zone distal to the one or more test zones, the absorbent zone being positioned relative to the sample addition zone and having an absorption capacity relative to the other zones of the test strip such that a distal diffusion front of a sample added to the sample addition zone diffuses from the sample addition zone to a distal diffusion point within the terminal sample flow zone and then reverses direction and diffuses proximal relative to the one or more test zones.
139 Citations
41 Claims
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1. A test strip adapted to receive a sample and detect an analyte therein, the test strip comprising:
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a sample addition zone to which a sample may be added;
an absorbent zone positioned on the test strip in a first flow direction relative to the sample addition zone, wherein the absorbent zone comprises an absorbent pad that is affixed to the test strip;
one or more test zones positioned on the test strip in a second, different flow direction relative to the sample addition zone, at least one of the test zones including a first analyte binding agent immobilized therein which is capable of binding to the analyte to be detected, the absorbent pad being in fluid communication with the sample addition zone and having an absorption capacity relative to the other zones of the test strip such that when a volume of sample within a predetermined sample volume range for the test strip is added to the sample addition zone, the sample initially diffuses from the sample addition zone both in the first flow direction to the absorbent zone and in the second flow direction past the one or more test zones and then reverses flow, and diffuses in the first flow direction past the one or more test zones toward the absorbent zone; and
a conjugate buffer addition zone positioned on the test strip in the second flow direction relative to where the sample reverses flow, such that when conjugate buffer is added to the conjugate buffer addition zone, the conjugate buffer diffuses in the first flow direction past the one or more test zones. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A test strip adapted to receive a sample and detect an analyte therein, the test strip comprising:
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a sample addition zone to which a sample may be added;
an absorbent zone positioned on the test strip in a first flow direction relative to the sample addition zone, wherein the absorbent zone comprises an absorbent pas that is affixed to the test strip;
one or more test zones positioned on the test-strip in a second, different flow direction relative to the sample addition zone, at least one of the test zones including a first analyte binding agent immobilized therein which is capable of binding to the analyte to be detected, the absorbent pad being in fluid communication with the sample addition zone and having an absorption capacity relative to the other zones of the test strip such that when a volume of sample within a predetermined sample volume range for the test strip is added to the sample addition zone, the sample initially diffuses from the sample addition zone both in the first flow direction to the absorbent zone and in the second flow direction past the one or more test zones and then reverses flow, and diffuses in the first flow direction past the one or more test zones toward the absorbent zone;
a conjugate buffer addition zone positioned on the test strip in the second flow direction relative to where the sample reverses flow, such that when conjugate buffer is added to the conjugate buffer addition zone, the conjugate buffer diffuses in the first flow direction past the one or more test zones; and
a zone positioned on the test strip in the second flow direction relative to where the sample reverses flow, which includes a second analyte binding agent which is capable of binding to the analyte and diffusing to the one or more test zones. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A test strip comprising:
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a first fluid addition zone to which a first fluid may be added;
an absorbent zone positioned on the test strip in a first flow direction relative to the first fluid addition zone, wherein the absorbent zone comprises an absorbent pas that is affixed to the test strip;
one or more test zones positioned on the test strip in a second, different flow direction relative to the first fluid addition zone, at least one of the test zones including a first analyte binding agent immobilized therein which is capable of binding to an analyte to be detected using the test strip, the absorbent pad being in fluid communication with the first fluid addition zone and having an absorption capacity relative to the other zones of the test strip such that when a volume of the first fluid within a predetermined volume range for the test strip is added to the first fluid addition zone, the first fluid initially diffuses from the first fluid addition zone both in the first flow direction to the absorbent zone and in the second flow direction past the one or more test zones and then, because of absorption by the absorbent pad, first fluid diffusing in the second direction reverses flow, and diffuses in the first flow direction past the one or more test zones toward the absorbent zone; and
a second fluid addition zone positioned on the test strip in the second flow direction relative to where the first fluid reverses flow, such that when the second fluid is added to the second fluid addition zone, the second fluid diffuses in the first flow direction past the one or more test zones. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for detecting an analyte in a sample comprising:
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applying the sample to a test strip wherein the sample (a) diffuses in a first flow direction toward an absorbent pad and in a second, different flow direction to one or more test zones, at least one of the test zones including a first analyte binding agent immobilized therein which binds to analyte in the sample, (b) diffuses past the one or more test zones in the second flow direction, and then (c) reverses flow and diffuses in the first flow direction past the one or more test zones, towards the absorbent pad;
delivering a conjugate buffer to a conjugate buffer addition zone which is positioned on the test strip in the second flow direction relative to where the sample reversed flow, delivery of the conjugate buffer causing a second analyte binding agent to diffuse in the first flow direction to the one or more test zones after the sample has reversed flow and diffuses in the first flow direction past the one or more test zones, the second analyte binding agent binding to analyte immobilized in the test zones; and
detecting the second analyte binding agent immobilized in the test zones which indicates that analyte is present in the sample. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification