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.