Lateral flow assays with time delayed components

• US 9,068,981 B2
• Filed: 09/19/2012
• Issued: 06/30/2015
• Est. Priority Date: 12/04/2009
• Status: Expired due to Fees

• Current Assignee: Rapid Pathogen Screening, Inc
• Original Assignee: Rapid Pathogen Screening, Inc
• Inventors: Babu, Uma Mahesh, VanDine, Robert W., Sambursky, Robert P.
• Primary Examiner(s): Nguyen, Bao Thuy L
• Assistant Examiner(s): Hollinden, Gary E
• Application Number:
  US13/622,791
• Publication Number:
  US 20130017559A1
• Time in Patent Office: 1,014 Days
• US Class Current: 1/1
• CPC Class Codes: B01L 2200/027 for microfluidic devices
• CPC Class Codes: B01L 3/5023 with a sample being transported to, and subsequently stored in an absorbent for analysis
• CPC Class Codes: B01L 3/502715 characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/502738 characterised by integrated valves microvalves F16K99/0001
• CPC Class Codes: G01N 33/5306 Improving reaction conditions, e.g. reduction of non-specific binding, promotion of specific binding
• CPC Class Codes: G01N 33/54388 based on lateral flow
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387

Abstract

A lateral flow device may include one or more enhancement elements, where the enhancement elements bind to the analyte sandwich to increase a detection signal in the test zone. In preferred embodiments, some or all of the enhancement elements are encapsulated.

Claims

1. A lateral flow device for detecting an analyte comprising:

a test strip comprising a sample application zone and a test zone;

a first conjugate comprising a first binding partner for the analyte and a label;

a second binding partner for the analyte capable of being immobilized in the test zone; and

at least one encapsulated enhancement element;

wherein the analyte, the conjugate, and the second binding partner form a sandwich which is immobilized in the test zone when the analyte is present; and

wherein the encapsulated enhancement element binds to the sandwich after being released from encapsulation to increase a detection signal in the test zone.

2. The lateral flow device of claim 1, wherein the label comprises colloidal gold and the enhancement element comprises at least one silver salt.

3. The lateral flow device of claim 1, wherein the enhancement element comprises an antigen and the first conjugate further comprises a third binding partner for the antigen.

4. The lateral flow device of claim 3, wherein the enhancement element further comprises a label.

5. The lateral flow device of claim 1, wherein the test zone comprises no molecule which specifically binds the analyte.

6. The lateral flow device of claim 1, wherein the second binding partner comprises a tag and the test zone comprises an immobilized binding partner of the tag.

7. The lateral flow device of claim 1, wherein:

the first binding partner for the analyte comprises a mixture of the first binding partner for the analyte conjugated to a tag and the first binding partner for the analyte without the tag;

the second binding partner for the analyte is immobilized in the test zone; and

wherein the enhancement element comprises a second conjugate comprising a label and a binding partner for the first binding partner for the analyte.

8. The lateral flow device of claim 7, wherein approximately 1-10% of the first binding partner for the analyte is conjugated to a tag.

9. The lateral flow device of claim 8, further comprising a tag binding partner with a detectable label, wherein when the tag binding partner is added to the test at the test zone, it increases a detection signal in the presence of analyte.

10. The lateral flow device of claim 1, wherein the enhancement element comprises an enzyme.

11. The lateral flow device of claim 1, wherein the enhancement element is encapsulated in a structure of a type selected from the group consisting of:

a) capsules;

b) pearls;

c) microbeads;

d) spheres;

e) crystals;

f) particles; and

g) any combination of a) through f).

12. The lateral flow device of claim 1, wherein the enhancement element is encapsulated in a material selected from the group consisting of cellulose and silica.

13. A method of enhancing a signal on a lateral flow device comprising a test strip comprising a sample application zone and a test zone, a conjugate comprising a first binding partner for an analyte in a sample and a label, a second binding partner for the analyte;

and an encapsulated enhancement element, comprising the steps of;

a) immobilizing a sandwich formed between the analyte, if present in the sample, the conjugate, and the second binding partner in a test zone of the lateral flow device;

b) delaying release of the enhancement element due to encapsulation; and

c) binding the enhancement element to the sandwich after being released from encapsulation such that the enhancement element increases a detection signal in the test zone.

14. The method of claim 13, wherein the enhancement element is in a volatile liquid.

15. The method of claim 13, wherein the conjugate further comprises colloidal gold and the enhancement element comprises at least one silver salt.

16. The method of claim 13, wherein the enhancement element comprises

an antigen and the conjugate further comprises a third binding partner for the antigen.

17. The method of claim 13, wherein the enhancement element further comprises a label.

18. The method of claim 13, wherein the test zone comprises no molecule which specifically binds the analyte.

19. The method of claim 13, wherein the enhancement element is encapsulated in a capsule of a type selected from the group consisting of:

a) capsules;

b) pearls;

c) microbeads;

d) spheres;

e) crystals;

f) particles; and

g) any combination of a) through f).

20. The method of claim 13, wherein the enhancement element is encapsulated in a material selected from the group consisting of cellulose and silica.

21. The method of claim 13, further comprising, before step a), the step of encapsulating the enhancement element.