Peroxidase-mimicking DNA-Ag/Pt nanoclusters mediated visual biosensor for CEA detection based on rolling circle amplification and CRISPR/Cas 12a

As a new type of nano-catalytic materials, silver-platinum nanoclusters have attracted more and more attention in the fields of biosensors and catalysis. A novel colorimetric method for CEA was developed based on the catalytic activity of peroxidase of DNA-Ag/Pt nanoclusters (NCs) and rolling circle amplification (RCA) and CRISPR/Cas12a. In this paper, DNA-Ag/Pt NCs can catalyze H2O2 to oxidize 3,3,5′,5′-tetramethyl benzidine (TMB) to form blue substance ox-TMB. Target CEA can specifically bind to the aptamer and releases the primer chain, which initiates the RCA reaction and activates the trans-cleavage activity of the Cas12a/crRNA, and the signal probe DNA-Ag/Pt NCs is hydrolyzed immediately, thus causing signal changes in the system. Due to signal amplification by combining RCA with CRISPR/Cas 12a system, the visual sensor has a high sensitivity for CEA with a linear range of 2.5 pg/mL to 2.0 ng/mL and a detection limit of 0.94 pg/mL (S/N = 3). Furthermore, the sensor has the advantages of good specificity, satisfactory results for the detection of actual samples and simple operation, indicating that this method has a potential application prospect in clinical detection.