Electrochemical detection of the p53 gene using exponential amplification reaction (EXPAR) and CRISPR/Cas12a reactions.

Abstract

Animproved electrochemical sensor has been developed for sensitive detection of the p53 genebased on exponential amplification reaction (EXPAR) and CRISPR/Cas12a. Restriction endonuclease BstNI is introduced to specifically identify and cleave the p53 gene, generating primers to trigger the EXPAR cascade amplification. A large number of amplified products are then obtained to enable the lateral cleavage activity of CRISPR/Cas12a. For electrochemical detection, the amplified product activates Cas12a to digest the designed block probe, which allows the signal probe to be captured by the reduced graphene oxide-modified electrode (GCE/RGO), resulting in an enhanced electrochemical signal. Notably, the signal probe is labeled with large amounts of methylene blue (MB). Compared with traditional endpoint decoration, the special signal probe effectively amplifies the electrochemical signalsby a factor of about 15.Experimental results show that the electrochemical sensor exhibits wide ranges from 500 aM to 10pM and 10pM to 1nM, as well as a relatively low limit detection of 0.39 fM, which is aboutan order of magnitude lowerthan that of fluorescence detection. Moreover, the proposed sensor shows reliable application capability in real human serum, indicating that this work has great prospects for the construction of a CRISPR-based ultra-sensitive detection platform.