Comparison of Six Aptamer-Aptamer Pairs on Rapid Detection of SARS-CoV-2 by Lateral Flow Assay.

Abstract

SARS-CoV-2 is a threat to humanity. Both the spike (S) protein and its receptor binding domain (sRBD) are extensively used for rapid detection. Although real-time reverse transcription polymerase chain reaction (rRT-PCR) is mostly used method for the molecular detection of SARS-CoV-2, rapid assays for antigenic detection are always needed. Lateral flow assays (LFAs) are the most commonly used tests for this purpose, and aptamers having stability and long shelf life are used as capture reagents. This study aimed to develop the LFAs based on the aptamer pairs for the antigenic detection of SARS-CoV-2 with the naked eye. Gold nanoparticles (AuNPs) were used as labels, and six sandwich models by three different aptamers were prepared using 4 μM and 8 μM probes and two kinds of membranes for developing the LFAs. The 8 μM probe concentration and M2 membrane showed the best recognition of both the synthetic sRBD and SARS-CoV-2 coming from the naso/oropharingeal swabs by designed LFAs as 100% sensitivity and 93.3% specificity compared to the antibody-detecting LFAs. Our developed strip assays based on aptamer pairs recognized the target directly in 5-6 min with the naked eye. It was also concluded that aptamer pairs, membrane types, assay buffers, and probe concentrations have a significant role in the detection of SARS-CoV-2 by LFAs. The detection of SARS-CoV-2 in clinical samples was demonstrated with the best aptamer pairs, sensitively and selectively among the designed six aptamer pairs for LFAs. Developed LFAs can be an alternative method to the conventional antibody-based LFAs for SARS-CoV-2 detection.