Carbon nanotube-based lateral flow immunoassay for ultrasensitive detection of proteins: application to the determination of IgG
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Authors report on a carbon nanotube (CNT)-based lateral flow immunoassay (LFI) for ultrasensitive detection of proteins. Shortened multiwalled CNTs were used as a colored (black) tag. The detection antibody was covalently immobilized on the CNT surface via diimide-activated conjugation between the carboxyl groups on the CNT surface and amino groups of antibodies. The assay involved the capture of target protein in a sandwich-type format between an immobilized capture antibody on the test zone of LFI and a CNT-labelled detection antibody. CNTs were thus captured on the test zone of the LFI and gave a black colored line to enable visual detection of protein. Quantitative results were obtained by reading the test line intensities with a portable strip reader. Rabbit IgG was used as a model target to demonstrate the proof-of-concept. Combining the advantages of lateral flow assay with the unique physical properties of CNT (color, high aspect-to-size ratio and ease of surface modification), the optimized LFI can detect of 1.3 pg mL−1 of rabbit IgG (S/N = 3). This is three orders lower than that of gold nanoparticle-based LFI. Rabbit IgG spiked into human plasma samples was successfully detected with this LFI. Conceivably, this method can be extended to various other proteins for which adequate antibodies do exist.
KeywordsCarbon nanotube Lateral flow assay Immunoassay Rabbit IgG Protein analysis
This research was support by the National Institute of Health, Centers of Biomedical Research Excellent (NIH, COBRE, Grant number: 1P20GM109024) and the National Natural Science Foundation of Anhui Province (Grant No: 1908085 MB54). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. G. Liu acknowledges the support from the Wanjiang Scholar Awards in Anhui Province, China.
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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