Native analyte as a reference in lateral flow assays
View Patent ↗This invention is directed to a lateral flow assay for detecting the presence of an analyte in a liquid test sample. The lateral flow assay represents an improvement in the ability to accurately and with high fidelity to detect the presence or absence of a target analyte in a liquid sample, in part, by encompassing a reference region of immobilized, non-diffusible analyte that allows for detection of any factors that interfere with the interaction and binding of the analyte to the labeled capture reagent. Any influences on the interaction and binding of the analyte that is free in solution in the liquid test sample to its complementary labeled reagent will be encountered in parallel in the binding between the immobilized analyte in reference region to the labeled reagent as it diffuses through the reference region. In one embodiment, the lateral flow assay of the invention is a urine-based human Chorionic Gonadotropin (hCG) assay.
1. A lateral flow sandwich assay device for detecting the presence of an analyte in a liquid sample, said assay device comprising: (a) a first region comprising a diffusibly bound labeled reagent complementary to an analyte in the liquid sample, wherein said diffusibly bound labeled reagent and said analyte form a diffusible first complex; (b) a test region comprising a non-diffusibly bound capture reagent capable of complexing with the first complex such that said analyte is bound between said non-diffusibly bound capture reagent and said diffusibly bound labeled reagent; (c) a control region comprising a non-diffusibly bound control reagent complementary to the diffusively bound labeled reagent and (d) a reference region comprising a predetermined concentration of non-diffusibly bound analyte that will complex with said diffusibly bound labeled reagent upon operation of the device to form a complex having a predetermined signal intensity, said non-diffusibly bound analyte having substantially the same affinity for said diffusibly bound labeled reagent as said diffusibly bound labeled reagent has for said analyte in the liquid sample such that any influences on the interaction and binding of analyte and diffusibly bound labeled reagent in said first region would be similarly encountered in the interaction and binding of said non-diffusibly bound analyte with said diffusibly bound labeled reagent in said reference region such that said predetermined signal intensity can serve as a_reference to indicate, by a comparison of the actual signal intensity of said reference region to said predetermined signal intensity, the presence of interferants that negatively impact the interaction and binding of analyte and diffusibly bound labeled reagent in said first region.
2. The lateral flow sandwich assay device of claim 1 , further comprising a matrix through which the liquid sample can flow by capillarity.
3. The lateral flow sandwich assay device of claim 2 , wherein said matrix comprises nitrocellulose.
4. The lateral flow sandwich assay device of claim 1 , wherein said diffusibly bound labeled reagent is complementary to an analyte selected from the group consisting of Follicular Stimulating Hormone (FSH), human Chorionic Gonadotropin (hCG), Luteinizing Hormone (LH), Gonorrhea antigen, Chlamydia antigen, Cross linked N-telopeptides, Deoxyprydinolone (Dpd), HIV antibodies and Nuclear Membrane Protein-22 (NMP-22).
5. The lateral flow sandwich assay device of claim 4 , wherein said analyte is human Chorionic Gonadotrophin (hCG).
6. The lateral flow sandwich assay device of claim 4 , wherein said analyte is Luteinizing Hormone (LH).
7. The lateral flow sandwich assay device of claim 1 , wherein said reference region is located between said first region and said test region.
8. The lateral flow sandwich assay device of claim 1 , wherein said reference region is located in between said test region and said control region.
9. The lateral flow sandwich assay device of claim 1 , wherein said diffusibly bound labeled reagent comprises an antibody.
10. The lateral flow sandwich assay device of claim 1 , wherein said diffusibly bound labeled reagent comprises an anti-hCG antibody capable of specifically binding with hCG to form a first complex of said labeled anti-hCG antibody and said hCG.
11. The lateral flow sandwich assay device of claim 1 , wherein said label is a gold sol.
12. The lateral flow sandwich assay device of claim 1 , wherein said label is colored latex particles.
13. The lateral flow sandwich assay device of claim 1 , wherein said predetermined concentration represents the minimum concentration at which the presence of the analyte can be detected visually and without instrumentation.
14. The lateral flow sandwich assay device of claim 1 , wherein said predetermined concentration represents the minimum concentration at which the presence of the analyte can be detected by an instrument having a detector capable of measuring the signal from the detectable label.
15. The lateral flow sandwich assay device of claim 1 , wherein said predetermined concentration is selected such that its predetermined signal intensity can be used to as a reference to indicate the presence of interferants that negatively impact the interaction and binding of analyte and diffusibly bound labeled reagent in said first region such that a signal detected in the reference region indicates that the assay is sensitive to the analyte at minimum detectable concentration.
16. The lateral flow sandwich assay device of claim 1 , wherein said predetermined concentration is selected such that its predetermined signal intensity can be used to as a reference to indicate the presence of interferants that negatively impact the interaction and binding of analyte and diffusibly bound labeled reagent in said first region such that the absence of signal in both of said reference region and said test region in combination with presence of signal in the control region indicates the likelihood of a false negative result.
17. The lateral flow sandwich assay device of claim 14 , wherein said instrument is a reflectance spectrometer.