Assay device, system and method
A system for treating a blood sample ( 700 ) having an analyte of interest comprises a strip ( 200 ) having a membrane ( 218 ), respective portions ( 216, 220 and 222 , or 300 ) which are provided for receiving the sample, for lysing cells of the sample to liberate hemoglobin, and for capturing glycated hemoglobin. The latter two portions ( 220 and 222 , or 300 ) of the membrane are treated with lysing and capture agents, respectively. A portion of the strip ( 214 or 230 or 240 ) is provided for holding an eluting agent and for releasing the agent upon a release condition. A system for detecting analyte comprises an optical subsystem ( 550 ) that is aligned with the strip to provide a signal corresponding to an amount of analyte, and an electronic subsystem ( 650 ) for processing the signal ( 560 ) to provide a result, such as an amount or percentage of glycated hemoglobin. To use these systems, the user simply applies a small sample ( 700 ) to the membrane ( 218 ) and closes a door ( 10 ) of the detection system over the strip ( 200 ) such that the door triggers the release of the eluting agent. No sample pre-treatment is required. The preferably handheld system ( 100 ) is a simple and convenient monitoring tool for the user, such as a diabetic patient who must monitor blood glucose on an on-going basis. While the systems are useful in the monitoring of blood glucose, they may be used for treating a sample other than blood and detecting an analyte other than an analyte in blood.
1. A method of treating a blood sample that comprises at least one analyte, comprising:
providing a strip comprising a membrane, the membrane comprising
a receiving portion for receiving the blood sample;
a first location having a first reagent disposed thereon, wherein the first reagent lyses cells in the blood sample; and
a second location downstream relative to the first location having a second reagent immobilized thereon, wherein the second reagent captures an analyte of the hemoglobin in the blood sample;
providing an eluting agent disposed on the strip upstream relative to the first location, wherein the eluting agent elutes hemoglobin in the blood sample;
applying an untreated whole blood sample to the receiving portion of the membrane;
allowing the eluting agent to flow downstream along the membrane and contact the untreated whole blood sample, and
detecting a level of the analyte captured at the second location.
2. The method of claim 1 , wherein the membrane has a property selected from wicking functionality, capillary functionality, porosity, and any combination thereof.
3. The method of claim 1 , wherein the first reagent is selected from a detergent, a hypotonic solution, and any combination thereof.
4. The method of claim 1 , wherein the eluting agent is selected from a buffer, a solvent, and any combination thereof.
5. The method of claim 1 , wherein the second reagent is selected from an antibody, a chemical reagent comprising at least one ligand for binding the analyte, and any combination thereof.
6. The method of claim 1 , wherein the analyte is glycated hemoglobin.
7. The method of claim 1 , wherein the membrane further comprises a third location downstream relative to the second location having a third reagent immobilized thereon, wherein the third reagent captures another analyte of the hemoglobin in the untreated whole blood sample.
8. The method of claim 7 , wherein the third reagent is selected from an antibody, a glycoprotein, a chemical reagent comprising at least one ligand for binding the another analyte, and any combination thereof.
9. The method of claim 7 , wherein the another analyte is non-glycated hemoglobin.
10. The method of claim 1 , wherein providing an eluting agent comprises providing a means for containing the eluting agent.
11. The method of claim 10 , wherein the means is selected from an absorbent pad, a pouch, a blister, and any combination thereof.
12. The method of claim 10 , wherein allowing the eluting agent to flow comprises releasing the eluting agent from the means.
13. The method of claim 12 , wherein the releasing is selected from breaking an integrity of the means, applying a pressure to the means, and any combination thereof.
14. The method of claim 1 , wherein the first location is downstream relative to the receiving portion for receiving the untreated whole blood sample.
15. The method of claim 1 , wherein said detecting comprises obtaining an optical signal that relates to the amount of the analyte captured at the second location.
16. The method of claim 1 , wherein the eluting agent is allowed to flow downstream when a release condition is met.
17. The method of claim 1 , wherein the first location is at the receiving portion for receiving the untreated whole blood sample.