SERS-based lateral flow immunoassay of troponin I by using gap-enhanced Raman tags

• Published in: Nano research Vol. 12; no. 2; pp. 413 - 420
• Main Authors: Khlebtsov, Boris N., Bratashov, Daniil N., Byzova, Nadezhda A., Dzantiev, Boris B., Khlebtsov, Nikolai G.
• Format: Journal Article
• Language: English
• Published: Beijing Tsinghua University Press 01-02-2019; Springer Nature B.V
• Subjects: Antigens; Atomic/Molecular Structure and Spectra; Biomarkers; Biomedicine; Biotechnology; Calcium-binding protein; Cardiovascular diseases; Chemistry and Materials Science; Colorimetry; Condensed Matter Physics; Coronary artery disease; Diagnostic systems; Gold; Heart; Heart diseases; Immunoassay; Infarction; Materials Science; Monoclonal antibodies; Myocardial infarction; Nanorods; Nanotechnology; Quantitative analysis; Raman spectra; Research Article; Sensitivity analysis; Tags; Target recognition; Troponin; Troponin I; cardiac Troponin I; surface-enhanced Raman scattering (SERS); gap-enhanced Raman tags; lateral flow immunoassay; Au core/shell nanorods
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-018-2232-4

The lateral flow immunoassay (LFIA) has emerged as a powerful tool for rapid screening owing to its simplicity and flexibility for detection of various biomarkers. However, conventional LFIA strips have several disadvantages, including limits in quantitative analysis and low sensitivity. Here we developed a novel surface-enhanced Raman scattering LFIA based on nonspherical gap-enhanced Raman tags (GERTs), with Raman molecules (RMs) embedded in a 1-nm gap between Au nanorod core and Au shell. Such tags have a strong and uniform SERS response, an order of magnitude higher than that of other common SERS tags such as Au nanorods, nanostars, Au nanoshells with surface-adsorbed RMs, or spherical GERTs with embedded RMs. The feasibility of the tags was demonstrated by the semiquantitative and sensitive detection of the heart disease biomarker cardiac troponin I (cTnI). GERTs were conjugated with monoclonal antibodies and used for LFIA in the same way as ordinary functionalized colloidal gold. The presence of the target antigen, cTnI, was identified by Raman microscopy mapping of the test zone. With the SERS-based LFIA, the limit of cTnI detection was about 0.1 ng/mL. This value is within the diagnostic range of cTnI in the blood serum of patients with heart infarction and is 30 times lower than that of the colorimetric LFIA test using the same antibodies and either GERTs or colloidal gold as labels.