Rapid and Sensitive SERS-Based Lateral Flow Test for SARS-CoV2-Specific IgM/IgG Antibodies

Area of Science:

• Immunology
• Analytical Chemistry
• Biotechnology

Background:

• COVID-19 infection triggers the development of SARS-CoV-2-specific IgM and IgG antibodies.
• Early serological diagnosis of acute infections is crucial for effective disease management.
• Conventional lateral flow assays (LFAs) are widely used but may lack sensitivity for early detection.

Purpose of the Study:

• To compare the performance of conventional LFAs with SERS-based LFAs for detecting SARS-CoV-2-specific IgM/IgG antibodies.
• To evaluate the potential of SERS-LFAs for sensitive and rapid serological diagnosis of COVID-19.
• To determine the limit of detection (LOD) for both assay types.

Main Methods:

• Conventional lateral flow assay (LFA) with naked-eye detection.
• Surface-enhanced Raman scattering (SERS)-based LFA using a custom-built reader.
• Detection of SARS-CoV-2-specific IgM/IgG antibodies in sera of COVID-19 patients.
• Reference measurements using purified IgM in buffer for absolute quantification and LOD determination.

Main Results:

• SERS-based LFAs demonstrated at least an order of magnitude higher sensitivity than conventional LFAs in serum samples.
• In a purified system, SERS detection achieved a LOD of approximately 100 fg/mL, which is 7 orders of magnitude lower than conventional detection (ca. 1 μg/mL).
• The study highlights the potential of SERS-LFAs for sensitive IgM detection, enabling earlier serological diagnosis.

Conclusions:

• SERS-based LFAs offer superior sensitivity for detecting SARS-CoV-2 antibodies compared to conventional LFAs.
• SERS-LFAs show significant potential for point-of-care testing and early serological diagnosis of COVID-19.
• Minimizing interference from serum components is key to fully realizing the potential of SERS-LFAs in clinical settings.