CRISPR/Cas13a-mediated triple signal amplification strategy for viral RNA detection

CRISPR/Cas13a system has been combined with different isothermal amplification strategies for RNA analysis. Nevertheless, expensive enzymes are usually indispensable in these isothermal amplification methods, which increases the detection cost. In this study, a CRISPR/Cas13a-mediated triple signal amplification strategy has been designed for selective, sensitive and inexpensive detection of viral RNA. SARS-CoV-2 S RNA activated CRISPR/Cas13a to cut hairpin DNA, triggering catalytic hairpin assembly (CHA) and subsequent hybridization chain reaction (HCR) to form a long-stranded Y-type DNA. G-quadruplexes were distributed on the branch of the long-stranded DNA and bound with N-methyl mesoporphyrin IX (NMM) to enhance the fluorescence signal. SARS-CoV-2 S RNA was specifically detected with a limit of detection (LOD) of 285 fM. Notably, no additional expensive enzymes were required in the entire detection process. The CRISPR/Cas13a-mediated triple signal amplification strategy holds great potential for specific and sensitive viral RNA detection with low cost.