A duplex-specific nuclease based electrochemical biosensor for the assay of SARS-CoV-2 RdRp RNA.

We present a method for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection based on the dual amplification effect of duplex-specific nuclease (DSN). In this scheme, we cleverly employed a 2-OMe-RNA modified DNA to prevent hairpin nucleic acid from being digested by DSN. The target RNA and 2-OMe-RNA are released when DSN cleaves just the double-stranded RNA/hairpin nucleic acid DNA. The target RNA then forms a circular reaction when it hybridizes with another hairpin nucleic acid. Simultaneously, the released target 2-OMe-RNA turns on the hairpin DNA2 on the electrode surface, and when the DSN cleaves the DNA in the hairpin DNA2/2-OMe-RNA duplex, the 2-OMe-RNA is released and hybridized with the other hairpin DNA2. The hairpin DNA2 on the electrode surface is split off after many cycles, exposing the gold electrode surface. As a consequence, there is more K 4 [Fe(CN) 6 ]/K 3 [Fe(CN) 6 ] redox near to the electrode surface, and the electrochemical signal increases. As a result, the change in electrochemical signal may be used to calculate the quantity of RNA that has to be measured. The protocol has good sensitivity in the detection of SARS-CoV-2: the detection limit reached 21.69 aM. This protocol provides an effective solution for the highly sensitive screening of SARS-CoV-2. [Display omitted] • Approach for SARS-CoV-2 assay based on a duplex-specific nuclease is reported. • 2-OMe-RNA-modified DNA was used to prevent the digestion of duplex-specific nuclease. • The detection of SARS-CoV-2 RNA in pharyngeal swabs was achieved. • This protocol has good sensitivity of 21.69 aM. • This protocol provides an effective solution for screening of SARS-CoV-2. [ABSTRACT FROM AUTHOR]