Leveraging Synthetic Antibody-DNA Conjugates to Expand the CRISPR-Cas12a Biosensing Toolbox.

We report here the use of antibody-DNA conjugates (Ab-DNA) to activate the collateral cleavage activity of the CRISPR-Cas12a enzyme. Our findings demonstrate that Ab-DNA conjugates effectively trigger the collateral cleavage activity of CRISPR-Cas12a, enabling the transduction of antibody-mediated recognition events into fluorescence outputs. We developed two different immunoassays using an Ab-DNA as activator of Cas12a: the CRISPR-based immunosensing assay (CIA) for detecting SARS-CoV-2 spike S protein, which shows superior sensitivity compared with the traditional enzyme-linked immunosorbent assay (ELISA), and the CRISPR-based immunomagnetic assay (CIMA). Notably, CIMA successfully detected the SARS-CoV-2 spike S protein in undiluted saliva with a limit of detection (LOD) of 890 pM in a 2 h assay. Our results underscore the benefits of integrating Cas12a-based signal amplification with antibody detection methods. The potential of Ab-DNA conjugates, combined with CRISPR technology, offers a promising alternative to conventional enzymes used in immunoassays and could facilitate the development of versatile CRISPR analytical platforms for the detection of non-nucleic acid targets.