Cotton thread as a low-cost multi-assay diagnostic platform
Hydrophilic threads as platforms for inexpensive, low volume, portable diagnostic systems, and methods of making the same are described. A diagnostic system includes a hydrophilic loading thread having an inlet zone at a proximal end; a testing zone at a distal end; and an intermediate zone located between the inlet zone and the testing zone, wherein the testing zone does not directly contact the inlet zone. In another aspect, a diagnostic system includes (i) a hydrophilic loading thread that includes an inlet zone at a proximal end and an intermediate zone at a distal end; and (ii) one or more additional hydrophilic threads that contact the intermediate zone of the loading thread. A method of detecting the presence or absence of an analyte in a fluid sample includes applying the sample to an inlet zone of a diagnostic system that includes a hydrophilic loading thread with an inlet zone at a proximal end; an intermediate zone; and a testing zone at a distal end; wherein the testing zone does not directly contact the inlet zone.
1. A system for performing an assay on a sample comprising one or more hydrophilic testing threads defining a sample inlet zone at a proximal end, an intermediate zone distal to the inlet zone through which fluid sample is carried by capillary action, and a testing zone distal to the intermediate zone and comprising a detection reagent which reacts with a predetermined analyte to produce a detectable signal.
2. The system of claim 1 further comprising a housing for support of the hydrophilic testing thread.
3. The system of claim 1 , wherein the signal is detectable by a naked eye or a spectrometer.
4. The system of claim 2 wherein at least a portion of the hydrophilic testing thread is enclosed within the housing to protect the hydrophilic testing thread from contamination and mechanical damage.
5. The system of claim 2 wherein the housing comprises two faces, and the hydrophilic testing thread is sewn into the housing and exposed on each face.
6. The system of claim 2 wherein the testing zone is enclosed within and visible from outside the housing.
7. The system of claim 1 wherein the detection reagent is a colorimetric detection reagent.
8. The system of claim 1 comprising an array of hydrophilic testing threads for performing multiple assays on a biological sample.
9. The system of claim 1 comprising a portion of a bandage or cloth.
10. The system of claim 1 comprising a portion of a woven array of hydrophilic testing threads.
11. The system of claim 2 comprising a portion of a woven array of hydrophilic testing threads.
12. The system of claim 1 wherein a said hydrophilic testing thread comprises multiple testing zones or multiple inlet zones.
13. The system of claim 2 wherein a said hydrophilic testing thread comprises multiple testing zones or multiple inlet zones.
14. The system of claim 1 for performing multiple assays on a sample further comprising
a housing, a hydrophilic loading thread comprising an inlet zone outside the housing, where one or more said hydrophilic testing threads communicate with said loading thread and at least a portion of the testing threads is enclosed within the housing.
15. The system of claim 14 further comprising in a said testing zone a detection reagent which reacts with a predetermined analyte to produce a signal apparent to the naked eye.
16. The system of claim 14 wherein at least two testing zones comprise different detection reagents.
17. A method of detecting an analyte in a fluid sample, the method comprising contacting an inlet zone of a system of claim 1 with a sample to induce sample flow by capillary action to a said testing zone and visually observing a signal at said testing zone.
18. The method of claim 17 comprising visually observing a plurality of signals at multiple detection zones.