Rapid and Sensitive SERS-Based Lateral Flow Test for SARS-CoV2-Specific IgM/IgG Antibodies
Supriya Srivastav, Asen Dankov, Mujo Adanalic, Roland Grzeschik, Vi Tran, Sibylle Pagel‐Wieder, Frank Gessler, Ingo Spreitzer, Tatjana Scholz, Barbara S. Schnierle, Olympia E. Anastasiou, Ulf Dittmer, Sebastian Schlücker
Abstract
As an immune response to COVID-19 infection, patients develop SARS-CoV-2-specific IgM/IgG antibodies. Here, we compare the performance of a conventional lateral flow assay (LFA) with a surface-enhanced Raman scattering (SERS)-based LFA test for the detection of SARS-CoV-2-specific IgM/IgG in sera of COVID-19 patients. Sensitive detection of IgM might enable early serological diagnosis of acute infections. Rapid detection in serum using a custom-built SERS reader is at least an order of magnitude more sensitive than the conventional LFAs with naked-eye detection. For absolute quantification and the determination of the limit of detection (LOD), a set of reference measurements using purified (total) IgM in buffer was performed. In this purified system, the sensitivity of SERS detection is even 7 orders of magnitude higher: the LOD for SERS was ca. 100 fg/mL compared to ca. 1 μg/mL for the naked-eye detection. This outlines the high potential of SERS-based LFAs in point-of-care testing once the interference of serum components with the gold conjugates and the nitrocellulose membrane is minimized.