Disposable dry-reagent cotton thread-based point-of-care diagnosis devices for protein and nucleic acid test

• Natural cotton thread-based point-of-care diagnosis devices.
• Simple preparation, low cost, rapid detection, and easy to handle.
• An enhancement protocol was employed by using two kinds of gold nanoparticle labels for protein test.
• The DNA test device has ability to visual discrimination of single base mismatched DNA sequence.

We report here for the first time by using dry-reagent cotton thread-based point-of-care diagnosis devices for low-cost, sensitive and rapid detection of a lung cancer related biomarker, squamous cell carcinoma antigen (SCCA) and a human genetic disease, hereditary tyrosinemia type I related DNA sequences. A model system comprising SCCA as an analyte and a pair of monoclonal antibodies is used to demonstrate the proof-of-concept on the dry-reagent cotton thread based immunoassay device. An enhancement protocol was employed by using two kinds of gold nanoparticle labels for SCCA test which greatly improved the sensitivity of the device. The assay avoids the multiple incubation and washing steps performed in most conventional protein analyses, which is similar with the lateral flow strip technology. Under optimal conditions, the thread based immunoassay device was capable of measuring 1 ng/mL SCCA in 20 min which meet the requirement for clinical diagnosis. DNA detection was successfully realized by using a novel adenosine based molecular beacon probe as reporter probes in the cotton thread based device, the linear range is 75–3000 fmol which is suitable for quantitative test.