Fluorometric and Colorimetric Method for SARS-CoV-2 Detection Using Designed Aptamer Display Particles

SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has spurred the urgent need for practical diagnostics with high sensitivity and selectivity. Although advanced diagnostic tools have emerged to efficiently control pandemics, they still have costly limitations owing to their reliance on antibodies or enzymes and require high-tech equipment. Therefore, there is still a need to develop rapid and low-cost diagnostics with high sensitivity and selectivity. In this study, we generated aptamer display particles (AdP), enabling easy fabrication of a SARS-CoV-2 detection matrix through particle PCR, and applied it to diagnosis using fluorometric and colorimetric assays. We designed two AdPs, C1-AdP and C4-AdP, displayed with SpS1-C1 and SpS1-C4 aptamers, respectively, and showed their high binding ability against SARS-CoV-2 spike protein with a concentration-dependent fluorescence increase. This enabled detection even at low concentrations (0.5 nM). To validate its use as a diagnostic tool for SARS-CoV-2, we designed a sandwich-type assay using two AdPs and high-quality aptamers targeting SARS-CoV-2 pseudoviruses. The fluorometric assay achieved a detection limit of 3.9 × 10³ pseudoviruses/mL. The colorimetric assay using an amplification approach exhibited higher sensitivity, with a detection limit of 1 × 10¹ pseudoviruses/mL, and a broad range of over four orders of magnitude was observed.