Figure 1.

Working principle of the EFE, immobilization-free electrochemical CRISPR biosensor for DNA detection. A) Trans-cleavage and cis-cleavage activities of CRISPR-Cas12a protein in the presence of crRNA, DNA target, and ssDNA (non-target). B) Operation procedures of the EFE, electrochemical CRISPR biosensor. (i) A pulsed electric field is applied to attract nucleic acids (e.g., electroactive ssDNA probe, dsDNA target) on the positively charged working electrode surface due to the static electric force. (ii) Electrochemical detection in the absence and presence of the target DNA. The trans-cleavage activity of activated Cas12a releases less negative MB-labeled probe, resulting in an increased electrochemical current during DPV detection.