A label-free electrochemical sensor for the detection of two kinds of targets based on CRISPR/Cas12a system

In recent years, electrochemical sensors for nucleic acid testing based on CRISPR/Cas12a technology have attracted widespread interest due to their ease of operation and high detection sensitivity. Here, a label-free electrochemical sensor amplified by primer exchange reaction (PER), hybridization chain reaction (HCR) and CRISPR/Cas12a system was developed for analyzing miRNA- 155 and PCB 77. In the presence of targets, PER was initiated, whose products could be used to trigger the trans-cleavage activity of Cas12a for the singlestranded DNA (ssDNA) on the electrode. Afterwards, with the amplification of HCR on the electrode and electrostatic adsorption of Ru(NH3)63+, the concentration of the targets could be indicated by the DPV intensity with a low background signal. The detection limits for miRNA- 155 and PCB 77 were estimated to be 67 aM and 6.9 pg/ L, respectively. This work provides a versatile method for sensitive detection of different targets using the same crRNA and can be used in various biochemical investigations.