An immunochromatographic assay for carcinoembryonic antigen on cotton thread using a composite of carbon nanotubes and gold nanoparticles as reporters.

This paper describes a low-cost, sensitive, visual and rapid immunochromatographic assay method on cotton thread for carcinoembryonic antigen (CEA) detection by using novel carbon nanotube/gold nanoparticles (CNT/GNPs) nanocomposite reporter probe. CEA, a lung cancer protein biomarker, was used as analyte to demonstrate the principle of the immunochromatographic assay on cotton thread biosensor. In the presence of target CEA, the decreasing aggregation amount of CNT/GNPs nanocomposite reporter probes on the test zone induced directly readout by naked eye. Meanwhile, quantitative detection could be performed conveniently with a commercial available scanner. The performance with respect to sensitivity of the method was greatly improved by 2-3 magnitudes comparing with traditional gold nanoparticles (GNPs) or carbon nanotubes (CNTs) as reporter probe. Under optimal conditions, the biosensor was capable of detecting 2.32 ng/mL CEA (S/N ≥ 3) which is sensitive enough for clinical diagnosis. These results indicated the novel CNT/GNPs nanocomposite reporter probe based immunochromatographic assay on cotton thread is particularly suitable for point-of-care (POC) diagnostics in resource-limited regions.