CRISPR/Cas12a-mediated electrochemiluminescence platform for environmental and human serum SARS-CoV-2 RNA monitoring using a self-enhanced ruthenium complex linked to zeolitic imidazole framework-8

Since the emergence of coronavirus disease 2019 (COVID-19), this highly contagious disease has ravaged the world, cumulatively causing millions of deaths and huge economic losses. As the culprit of COVID-19, severe acute respiratory syndrome beta-coronavirus 2 (SARS-CoV-2) is highly infectious and pathogenic, which has caused extreme panic worldwide. Early and rapid monitoring of SARS-CoV-2 has a significant role in suppressing the pandemic and reducing the virus's lethality. In our work, we prepared a self-enhanced ruthenium complex linked to zeolitic imidazole framework-8 (ZIF-8) and used it as an electrochemiluminescence (ECL) emitter. Additionally, a double-stranded specific nuclease (DSN)-assisted target RNA cycling with catalytic hairpin assembly (CHA) signal amplification technology was used to achieve the conversion of target RNA concentration to double-stranded DNA (dsDNA) output which significantly improved the detection sensitivity of target RNA under environmental conditions and in real human serum samples. In addition, we also combined the trans-cleavage property of CRISPR-Cas12a with the adsorption property of C3N4 on a ferrocene (Fc)-labeled DNA probe and obtained target RNA-dependent ECL signals. The reliable detection protocol achieved the transformation of SARS-CoV-2 RNA concentration to ECL responses, obtaining a limit of detection (LOD) of 0.67 fM with high specificity and reproducibility, which was of guiding significance for current detection methods of mutant SARS-CoV-2 and universal RNA.