Construction of a CRISPR-Biolayer Interferometry Platform for Real-Time, Sensitive, and Specific DNA Detection.

The clustered regularly interspaced short palindromic repeats (CRISPR) technology has been widely applied for nucleic acid detection because of its high specificity. By using the highly specific and irreversible bond between HaloTag and its alkane chlorine ligand, we modified dCas9 (deactivated CRISPR/Cas9) with biotin as a biosensor to detect nucleic acids. The CRISPR biosensor was facilely prepared to adequately maintain its DNA-recognition capability. Furthermore, by coupling biolayer interferometry (BLI) with the CRISPR biosensor, a real-time, sensitive, and rapid digital system called CRISPR-BLI was established for the detection of double-stranded DNA. The CRISPR biosensor immobilised on the biolayer could recruit the target DNA onto the biosensor surface and change its optical thickness, resulting in a shift in the interference pattern and responding signal of the BLI. The CRISPR-BLI system was further applied to detect the ALP gene of Escherichia coli DH5α combined with a polymerase chain reaction, which demonstrated a linear range from 20 to 20 000 pg and a low detection limit (1.34 pg). The CRISPR-BLI system is a promising approach for rapid and sensitive detection of target DNA analytes.