CRISPR/Cas12a controlled chemiluminescence resonance energy transfer sensor for detection of carcinoembryonic antigen

A CRISPR-Cas12a controlled chemiluminescence resonance energy transfer (CRET) biosensor was constructed for the detection of cancer biomarker carcinoembryonic antigen (CEA). The CRET probe, a single-strand DNA (ssDNA) with hemin/G-quadruplex on one end and CdSe/ZnS quantum dots (QDs) nanosphere on the other end, was used as the substrate for the trans-cleavage of CRISPR/Cas12a system. The hemin/G-quadruplexes catalyzed the oxidation of luminol in the presence of H2O2. The generating chemiluminescence could excite the CdSe/ZnS QDs encapsulated in the nanosphere, producing CRET. When target CEA specifically identified dual aptamers on the surface of magnetic beads (MBs), the terminal sequence of Aptamer 2 triggered the hybridization chain reaction (HCR), whose product initiated the trans-cleavage activity of CRISPR/Cas12a and destroyed the CRET system. As a result, the luminescence of QDs nanosphere was declined. With HCR, CRISPR-Cas12a trans-cleavage, and mimic DNAzyme catalytic amplification, the biosensor gave a detection limit down to 5.6 pg/mL. Due to the application of CRISPR/Cas12a, the CRET sensor with the characteristics of easy operation and no external light source required was more suitable for point-of-care testing (POCT) detection of various targets.