Assay device and reader
The present invention relates to a microfluidic based assay system, comprising a disposable assay cartridge and associated reading device, as well as the individual components themselves. The present invention also relates to methods of conducting assays, using the cartridge and device of the invention, as well as kits for conducting assays.
1. A method of conducting an assay on a liquid sample, the method comprising:
(a) providing a microfluidic cartridge comprising
(i) a substrate defining a microfluidic channel and comprising a magnetic binding agent and a fluorescently labeled binding agent disposed within the channel for binding an analyte to be detected in the liquid sample, wherein the magnetic binding agent and the fluorescently labeled binding agent each comprise a separate binding agent that binds the analyte such that, if analyte is present in the liquid sample, both the magnetic binding agent and the fluorescently labeled binding agent bind the analyte to form a fluorescently labeled complex, and wherein the binding agent of the magnetic binding agent is bound to a magnetic or paramagnetic particle, and
(ii) a sample port in fluidic communication with the channel for introducing the liquid sample into the channel;
(b) introducing the liquid sample into the channel via the sample port to permit an analyte, if present in the liquid sample, to bind the magnetic binding agent;
(c) applying a magnetic field to the cartridge to concentrate and hold the magnetic binding agent in a detection area within the channel;
(d) removing unbound material from analyte bound within the detection area with air, wherein, when the fluid sample introduced in step (b) is whole blood that comprises a component that interferes with a fluorescent signal produced by the fluorescently labeled complex, the component is removed from the detection area with the air; and
(e) detecting, in a non-liquid environment, analyte bound by the magnetic binding agent held in the detection area via a fluorescent signal produced by the fluorescently labeled complex, if analyte is present in the liquid sample.
2. The method of claim 1 , wherein, when the channel further comprises a liquid stop feature disposed between the sample port and the magnetic binding agents, the method further comprises actively moving the liquid sample past the liquid stop feature so that the liquid contacts the magnetic binding agents.
3. The method of claim 2 , wherein the liquid stop feature comprises a hydrophobic material.
4. The method of claim 2 , wherein the step of actively moving the liquid sample past the liquid stop feature is accomplished by a pump.
5. The method of claim 3 , wherein the step of actively moving the liquid sample past the liquid stop feature is accomplished by a pump.
6. The method of claim 1 , wherein the fluorescently labeled complex is formed, if analyte is present in the liquid sample, before the magnetic field is applied in step (c).
7. The method of claim 1 , wherein the fluorescently labeled complex is formed, if analyte is present in the liquid sample, after the magnetic field is applied in step (c).
8. The method of claim 6 , wherein the fluorescently labeled complex is held within the detection area by the magnetic field and is detected during step (e).
9. The method of claim 7 , wherein the fluorescently labeled complex is held within the detection area by the magnetic field and is detected during step (e).
10. The method of claim 8 , wherein unbound fluorescently labeled binding agent is removed from the detection area by the air.
11. The method of claim 9 , wherein unbound fluorescently labeled binding agent is removed from the detection area by the air.
12. The method of claim 1 , wherein, during step (e), analyte remaining in an air environment and bound by the magnetic binding agent in the detection area is detected.
13. The method of claim 1 , wherein the substrate comprises a sandwich of three layers wherein a middle layer is disposed between and adhered to a top layer and a bottom layer, and wherein the three layers together define the channel.
14. The method of claim 1 , wherein, during step (d), the air is introduced into the channel from a reservoir of an associated reader.
15. The method of claim 1 , wherein the liquid sample comprises whole blood, plasma, saliva, semen, sweat, serum, menses, amniotic fluid, tears, a tissue swab, urine, cerebrospinal fluid, or mucous.
16. The method of claim 15 , wherein the liquid sample comprises whole blood.
17. The method of claim 15 , wherein the liquid sample comprises urine.