Lateral Flow Immunoassay of SARS-CoV-2 Antigen with SERS-Based Registration: Development and Comparison with Traditional Immunoassays

Abstract

The current COVID-19 pandemic has increased the demand for pathogen detection methods that combine low detection limits with rapid results. Despite the significant progress in methods and devices for nucleic acid amplification, immunochemical methods are still preferred for mass testing without specialized laboratories and highly qualified personnel. The most widely used immunoassays are microplate enzyme-linked immunosorbent assay (ELISA) with photometric detection and lateral flow immunoassay (LFIA) with visual results assessment. However, the disadvantage of ELISA is its considerable duration, and that of LFIA is its low sensitivity. In this study, the modified LFIA of a specific antigen of the causative agent of COVID-19, spike receptor-binding domain, was developed and characterized. This modified LFIA includes the use of gold nanoparticles with immobilized antibodies and 4-mercaptobenzoic acid as surface-enhanced Raman scattering (SERS) nanotag and registration of the nanotag binding by SERS spectrometry. To enhance the sensitivity of LFIA-SERS analysis, we determined the optimal compositions of SERS nanotags and membranes used in LFIA. For benchmark comparison, ELISA and conventional colorimetric LFIA were used with the same immune reagents. The proposed method combines a low detection limit of 0.1 ng/mL (at 0.4 ng/mL for ELISA and 1 ng/mL for qualitative LFIA) with a short assay time equal to 20 min (at 3.5 h for ELISA and 15 min for LFIA). The results obtained demonstrate the promise of using the SERS effects in membrane immuno-analytical systems.

Current Advances in Paper-Based Biosensor Technologies for Rapid COVID-19 Diagnosis

“…In this study, the authors confirmed that the sensitivity of SERS-based LFA (100 fg/mL) was seven orders of magnitude higher than that of naked-eye detection (1 μg/mL) for detecting IgM antibodies in a buffer. Similar studies [ 123 , 124 ] have been performed by altering SERS tags or plasmonic nanomaterials, and in all these studies, the sensitivity of SERS-based LFAs was significantly improved compared to that of conventional LFAs.…”

Progress in Electrochemical Biosensing of SARS-CoV-2 Virus for COVID-19 Management

“…In comparison to the above diagnosis methods, lateral flow immunoassay (LFIA) platforms with optical detection (colorimetry/fluorescence), enzyme-linked immunosorbent assay (ELISA), chemiluminescent immunoassay (CIA), and electrochemistry-based serological test (detection of antibody and antigen) have received much attention for diagnosis COVID-19 (Figure 1b) [13][14][15][16][17]. In particular, electrochemistry-based SARS-CoV-2 virus detection systems have received great potential over 'gold standard' RT-PCR, NA amplification assays, and optical methods.…”

Development and evaluation of time‐resolved fluorescent immunochromatographic assay for quantitative detection of SARS‐CoV‐2 spike antigen

“…Surface‐enhanced Raman scattering (SERS)‐based probes have been investigated for both detection and registration of SARS‐CoV‐2 antigen. SERS‐based immunoassays generally do not exhibit matrix effects, enabling direct measurement of antigens without pre‐treatment of biological samples, 41,42 in contrast to conventional fluorescence detection methods 43,44 . Karakus et al 45 reported colorimetric and electrochemical detection of SARS‐CoV‐2 spike protein with gold nanoparticle‐based biosensors to detect as little as 1 pg/ml of the spike protein with linearity over four orders of magnitude.…”