Magnetic beads for reducing leukocyte interference in immunoassays
First Claim
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1. A method of reducing interference from leukocytes in an analyte immunoassay, comprising:
- contacting a biological sample containing leukocytes with magnetic beads opsonized to said leukocytes under conditions sufficient to substantially bind the leukocytes in the biological sample to the opsonized magnetic beads; and
magnetically retaining the opsonized magnetic beads in the biological sample substantially out of contact from an immunosensor to prevent leucocyte interference;
wherein the opsonized magnetic beads are present in an amount in excess of the leukocytes in the sample sufficient to substantially sequester any leukocytes present in the sample.
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Abstract
Methods and devices for reducing interference from leukocytes in an analyte immunoassay are provided. In one embodiment, a method is provided comprising the steps of amending a biological sample with magnetic sacrificial beads opsonized to leukocytes, binding leukocytes in the sample to the magnetic sacrificial beads, and magnetically retaining the beads out of contact from an immunosensor.
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Citations
53 Claims
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1. A method of reducing interference from leukocytes in an analyte immunoassay, comprising:
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contacting a biological sample containing leukocytes with magnetic beads opsonized to said leukocytes under conditions sufficient to substantially bind the leukocytes in the biological sample to the opsonized magnetic beads; and magnetically retaining the opsonized magnetic beads in the biological sample substantially out of contact from an immunosensor to prevent leucocyte interference;
wherein the opsonized magnetic beads are present in an amount in excess of the leukocytes in the sample sufficient to substantially sequester any leukocytes present in the sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of performing an analyte sandwich immunoassay in a blood sample, comprising:
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introducing a blood sample containing leukocytes into a holding chamber in a test cartridge, wherein a portion of the holding chamber is coated with magnetic beads opsonized to leukocytes; contacting the blood sample with the opsonized magnetic beads under conditions sufficient to substantially bind the leukocytes in the biological sample to the opsonized magnetic beads wherein the opsonized magnetic beads are present in an amount in excess of the leukocytes in the sample sufficient to substantially sequester any leukocytes present in the sample; moving the blood sample containing the opsonized magnetic beads into a conduit, wherein a magnetic field localized to at least a portion of the conduit attracts and retains the opsonized magnetic beads, including opsonized magnetic beads bound to leukocytes, on at least a portion of the wall of the conduit thereby substantially preventing the opsonized magnetic beads from coming into contact with an immunosensor; further contacting the blood sample with the immunosensor to form a sandwich complex comprising an immobilized capture antibody immobilized on the immunosensor bound to a sample analyte which is bound to a signal antibody;
wherein the capture antibody and the signal antibody bind specifically to the analyte;optionally washing unbound components in the blood sample from the immunosensor; and detecting the presence of the analyte based on a signal provided by the signal antibody in said sandwich complex. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method of performing an analyte competitive immunoassay in a blood sample, comprising:
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introducing a blood sample containing leukocytes into a holding chamber in a test cartridge, wherein a portion of the holding chamber is coated with magnetic beads opsonized to leukocytes; contacting the blood sample with a labeled analyte; contacting the blood sample and the labeled analyte with the opsonized magnetic beads under conditions sufficient to substantially bind the leukocytes in the biological sample to the opsonized magnetic beads wherein the opsonized magnetic beads are present in an amount in excess of the leukocytes in the sample sufficient to substantially sequester any leukocytes present in the sample; moving the blood sample, labeled analyte and opsonized magnetic beads into a conduit; applying a magnetic field localized to at least a portion of a conduit to attract and retain the opsonized magnetic beads, including opsonized magnetic beads bound to leukocytes, on at least a portion of a wall of the conduit thereby substantially preventing the opsonized magnetic beads from coming into contact with an immunosensor having on its surface a reagent with a specific binding affinity for the analyte and labeled analyte; futher contacting the blood sample with the immunosensor having immobilized on its surface an antibody with a specific binding affinity for the analyte and labeled analyte to form a competitive ratio of bound sample analyte to bound labeled analyte; optionally washing unbound components in the blood sample from the immunosensor; and determining the presence of the sample analyte based on the competitive ratio and the inverse relationship between the amount of analyte in the blood sample and the amount of bound labeled analyte as detected by a signal provided by the bound labeled analyte. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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Specification