The pandemic of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is continuously worsening globally, herein we have proposed an electrochemical biosensor for the sensitive monitoring of SARS-CoV-2 RNA. The presence of target RNA firstly triggers the catalytic hairpin assembly circuit and then initiates terminal deoxynucleotidyl transferase-mediated DNA polymerization. Consequently, a large number of long single-stranded DNA products can be produced, and these negatively charged DNA products will bind a massive of positively charged electroactive molecular of Ru(NH3)63+ due to the electrostatic adsorption. Therefore, significantly amplified electrochemical signals can be generated for sensitive analysis of SARS-CoV-2 RNA in the range of 0.1-1000 pM with the detection limit as low as 26 fM. Besides the excellent distinguishing ability for SARS-CoV-2 RNA against single-base mismatched RNA, the proposed biosensor can also be successfully applied to complex matrices, as well as clinical patient samples with high stability, which shows great prospects of clinical application.
An electrochemical biosensor for sensitive analysis of the SARS-CoV-2 RNA