4.4. PEC detection
A Cas12a–crRNA duplex was prepared by adding crRNA (20 μM) and Cas12a protein (20 μM) to the reaction buffer and incubating at room temperature for 10 min. Then 190 μL of this Cas12a–crRNA duplex was mixed with 10 μL of cDNA and incubated at room temperature for 10 min to facilitate the formation of the Cas12a–crRNA–target complex. 200 μL of the Cas12a–crRNA–target complex solution was added to an electrode surface covered with a CdTe/ZnS QDs–dsDNA reporter, followed by incubation at 37°C for 30 min. The electrode surface was then cleaned by immersing in PBS buffer for 5 min prior to PEC detection. PEC detection was carried out in PBS buffer (0.1 M, pH 7.4) at room temperature with the addition of 0.1 M KCl. The white light source was provided by a Xe lamp, which was cycled on and off at 10-second intervals. The applied potential during the experiment was 0.3 V.