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Development of One-step Vertical Flow Immunoassay System for Onsite Diagnosis Assisted by Surface-enhanced Raman Scattering
Biomed Sci Letters 2024;30:325-334
Published online December 31, 2024;  https://doi.org/10.15616/BSL.2024.30.4.325
© 2024 The Korean Society For Biomedical Laboratory Sciences.

Ha-Young Cho1,* and Il-Hoon Cho1,2,†,**

1Department of Senior Healthcare, Eulji University, Seongnam 13135, Korea
2Department of Biomedical Laboratory Science, College of Health Science, Eulji University, Seongnam 13135, Korea
Correspondence to: †Il-Hoon Cho
Department of Biomedical Laboratory Science, College of Health Science, Eulji University, 553 Sanseong-daero, Sujeong-gu, Seongnam 13135, Korea
Tel: +82-31-740-7397, Fax: +82-31-740-7284
E-mail: ihcho@eulji.ac.kr
ORCID: https://orcid.org/0000-0002-4991-2268

*Graduate student, **Professor.
Received November 28, 2024; Revised December 17, 2024; Accepted December 17, 2024.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
Objectives: A study was conducted to address two major limitations of the vertical flow assay (VFA) used in point-of-care diagnostics: low sensitivity due to visual analysis, and the inconvenience of requiring multiple steps, such as washing.
Methods: To overcome these issues, in this study, the VFA was integrated with surface-enhanced Raman scattering (SERS) for high sensitivity and applied a one-step analysis method using a premix. The developed one-step SERS-based VFA system is labeled by a Raman probe consisting of detection antibodies, Raman reporter (4-mercaptobenzoic acid [4-MBA]), and gold nanoparticles, and is based on a sandwich system composed of capture antibodies and analytes. To facilitate immediate SERS measurement, a customized cartridge was designed to eliminate the need for removal before analysis. Sensitivity was further improved by optimizing the sample dilution buffer, concentration of the capture antibody, and size of gold nanoparticles embedded in the Raman probe.
Results: Using only 60 μL of analyte, the system exhibited excellent linearity (R2 = 0.9988) up to 10 ng/mL, with a detection limit of 0.66 ng/mL for the C-reactive protein (CRP) antigen, outperforming traditional lateral flow and VFAs.
Conclusion: This is superior to the lateral flow assay and VFA, which use CRP antigen as a biomarker. It is emphasized that the developed one-step SERS-based VFA system can be used as a potential point-of-care testing tool for diagnosing various biomarkers as well as CRP.
Keywords : Vertical flow assay, Raman scattering, Point-of-care testing, Signal enhancement, Immunoassay