Ultrasensitive electrochemical detection of parvovirus B19 DNA by combining CRISPR-Cas12a and multivalent framework nucleic acids

diagnostics to enable time-critical interventions and contain community transmission. Herein, we developed an electrochemical biosensor as a proof-of-concept for B19V by integrating CRISPR-Cas12a with multivalent framework nucleic acids (FNAs), namely, 12 nm tetrahedral DNA nanostructures (TDNs). Target B19V DNA activates Cas12a to indiscriminately cleave the biotin-modified ssDNA protruding from the four vertices of the TDNs, while the TDNs precisely orient ssDNA probes on electrodes, minimizing nonspecific adsorption. This method takes advantage of the target-specific cleavage ability of CRISPR-Cas12a (Cas12a-crRNA complex, 10-12 nm) and the unique structural and functional features of 12 nm TDNs. The comparable dimensions of the Cas12a-crRNA complex and the TDN suggest a potential synergistic effect, which contributes to the observed signal amplification and high detection sensitivity. The developed platform is user-friendly, has a low detection limit (2.19 fM), and shows high selectivity. This work establishes a foundational biosensing platform, demonstrating potential for ultrasensitive nucleic acid detection. By combining the accuracy of CRISPR-Cas12a and the benefits of FNAs, this method provides a more efficient, amplification-free, and reliable approach that holds promise for future development in point-of-care diagnostics and other applications.